Genetics and the Social Behavior of the Dog - gwern · 2019-03-11 · genetics and schizophrenia. A committee on behavior genetics has been set up by the Social Science Research Council

PREFACE

Oneofthemajorbasicproblemsofpsychologyandbiologyistheeffectofheredityuponbehavior;yetinthe1930'sandearly1940'sresearchinthisareahadalmostcompletelygoneoutofstyle.Atthattimeitwaspossibletocountonthefingersofonehandthepersonswhohaddonesignificantresearchinthefield.Tryonhaddoneanextensiveexperimentonheredityandmazerunninginrats,followedupbyimportantstudiesfromhisstudents,HallandSearle.Dawsonhadbeguntoworkwithbehaviorindogs,buthisprojectwasterminatedbytheoutbreakofwar.

Inthehumanarea,interestintheThirtieswaslargelyconfinedtoasomewhatsterilecontroversyovertheextenttowhichIQscorescouldbemodifiedbyspecialtraining,althoughThurstoneandStrandskovhadbecomeinterestedinapplyingthetechniqueoffactorialanalysistoproblemsofbehaviorgenetics.AmongmostscientiststherehadbeenarevulsionagainsttheexaggeratedclaimsoftheearlyeugenicistsandtheracistdoctrinesofNaziGermany,anditwasnotinfrequentlystatedthatheredityhadnoeffectuponhumanbehavior.

ItwasagainstthisgeneralbackgroundthatDr.AlanGregg,thenDirectorfortheMedicalSciencesattheRockefellerFoundation,wenttolunchwithDr.C.C.Little,thedirectorandfounderoftheJacksonLaboratory,andexpressedtheopinionthatpsychiatristsandsociologistswerepayingtoolittleattentiontothefactorofheredityasitaffectedbehavior.Dr.Little'simaginationcaughtfire,andtheoutcomewasatentativearrangementforalong-rangeproject,laterknownas"GeneticsandtheSocialBehaviorofMammals."

Theresultsofthatprojectarenowsummarizedinthisbook,whichisprimarilyanaccountofanexperimentlastingsomethirteenyearsandinvolvingintensiveandextensivemeasurementsonthebehaviorofhundredsofpurebredandhybriddogs,studiedfrombirthtooneyear.Astheexperimentprogressed,weweremoreandmoreimpressedwiththedevelopmentalapproachtotheproblemofthegeneticsofbehavior,andmuchofourworkispresentedfromthatviewpoint.Inaddition,wehaveanalyzedthegeneticresultsbymostoftheconventionalstatisticalmethodsandhavedevelopedcertainnewonesaswell.Finally,wehaveshownhowtheseresultsrelatetothegeneralproblemsofhumanandanimalbehavior.

Aswellaspresentingourownwork,wehavecollectedagreatdealof

Aswellaspresentingourownwork,wehavecollectedagreatdealofbackgroundinformationontheoriginandnatureofgeneticdiversityindogs.Thebookasawholeisthereforeasourceofgeneralinformationonbehaviorofdogsandshouldbeofinteresttodogownersandbreedersaswellastheoreticalscientists.

Thisis,naturally,notthelastwordonthesubject.Ourworkhasraisedasmanynewquestionsasithasansweredoldones,andwepresentourfindingstodateinthehopethattheymayprovideabackgroundformuchneededfuturework.Onethingwhichhasimpressedusisthatthedog,forallitseightthousandyearsorsoofassociationwithhumanbeings,isstillinmanyrespectsascientificallyunknownanimal.Despitethehundredsofpapersthathavebeenpublishedaboutthisanimal,therearevastareasofinformationwhicharestillunexplored.Withthemoregeneroussupportnowavailableforresearch,itshouldeventuallybepossibletoknowinsteadofmerelyspeculateaboutthenatureofman'sbestfriend.

Whilethisexperimenthasbeengoingon,muchprogresshasbeenmadeelsewhereandinmanyscientificdisciplines.Manyworkershavecontributedtotherevivalofinterestintheproblemofgeneticsandbehavior,inparticulartheethologistsundertheleadershipofTinbergenandLorenz,whosestudiesofinstincthavereformulatedthequestionofgeneticdifferencesbetweenspecies.Inotherfields,symposiaonbehaviorgeneticshavebeenheldatthetwo1963InternationalCongressesofgeneticsandpsychology.ArecentpresidentialaddressoftheAmericanPsvchologicalAssociationwasdevotedtothesubjectofgeneticsandschizophrenia.AcommitteeonbehaviorgeneticshasbeensetupbytheSocialScienceResearchCouncil.AtasymposiumoftheAmericanPsychiatricSociety(publishedafterwardasavolumeentitledRootsofBehavior)one-fourthotthepapersweredirectlyconcernedwithbehaviorgenetics,

PREFACEvH

andeightofthethirty-oneauthorshadsomedirectassociationwiththeJacksonLaboratory.

IfAlanGreggwerealivetoday,wethinkthathewouldbepleasedwiththeresults.

J.P.Scott

J.L.Fuller

J.L.Fuller

ACKNOWLEDGMENTS

Thepronoun"we"isuseddeliberatelyinthisbook,notonlybecauseithastwoauthors,butinrecognitionofthecontributionsmadebyournumerousco-laborersontheproject.

Weparticularlywishtorecognizetheeffortsofourresearchassistants,onwhomtheaccuracyandintegrityofthedatasolargelydepended.Manyofthemhavesincegoneontoadvancedtrainingandhavebecomeindependentinvestigators.WeareespeciallyindebtedtoMargaretCharlesHigginsandEdnaDuBuisfortheirlongperiodsofservice,andtoC.L.Brace,OrvilleElliot,AlbertPawlowski,andJosephRoycefortheircontributionstodataanalysis.Otherswhomadecontributionsoverthe13-yearspanoftheprojectwereDuaneBlume,MarianBurns,JohnCraig,Jr.,DonaldDickerson,ClariceEasier,AlanE.Fisher,PriscillaHinch-cliffe,DavidKing,NancyM.King,MonaMeltzer,RobertPettie,MaxineSchnitzer,JoyceSprague,MaryE.Smith,andElizabethWilliams.

Wewerefortunateinhavingoverthewholeperiodmuchthesamegroupofgeneralassistants,onwhomauniformsystemofcarefortheanimalsdepended.WeespeciallythankFrankClark,GordonGilbert,SheldonIngalls,PearlMcFarland,andDanReynolds.

Manyscientificinvestigatorsmadenotablecontributions.C.C.Little,thentheDirectoroftheJacksonLaboratory,acquiredthefoundationstocksandworkedoutthecolorgeneticsofthebreeds;C.S.HallandW.T.Jamesgaveadviceandhelpedorganizetheproject;B.E.GinsburgandShermanRosscontributedmuchaslongtimeVisitingInvestigators.Othercolleaguesandassociatestoonumeroustomentionherehelpedwithencouragementandcounsel.

xACKNOWLEDGMENTS

MajorfinancialsupportwasgivenbytheRockefellerFoundationovera13-yearperiodduringwhichthebasicdataweregathered.ContinuingsupportenablingtheprocessingofthedataandwritingthisbookwasprovidedbytheFordFoundationandbytheNationalInstitutesofHealth(GrantsMH01775andMH04481).

Certainfiguresandtableshavebeenpreviouslypublishedinthefollowingbooksandjournals:TheConceptofDevelopment(UniversityofMinnesotaPress,

andjournals:TheConceptofDevelopment(UniversityofMinnesotaPress,1957),JournalofComparativeandPhysiologicalPsychology,AnimalBehaviour,JournalofHeredity,AmericanZoologist,MonographsoftheSocietyforResearchinChildDevelopment,Science,JournalofGeneticPsychology,PsychosomaticMedicine,andAnnalsoftheNewYorkAcademyofSciences.Permissiontoreproducethismaterialisherebyacknowledged.

CONTENTS

PartIVGENERALIMPLICATIONS

15.IMPLICATIONSFORTHEARTOFDOGBREEDING/383

16.THEEVOLUTIONOFDOGSANDMEN/397

17.TOWARDASCIENCEOFSOCIALGENETICS/413

BIBLIOGRAPHY/435AUTHORINDEX/449SUBJECTINDEX/452

PLATESfollowingpage176

Thefivepurebreeds

Outsiderunsandnurseryroominterior

TheBehaviorLaboratoryandstaff

Breedingstock(cockerspaniels)andFjhybrids

Breedingstock(basenjis)andFxhybrids

Litterfrombackcrosstocockerspaniel

Litterfrombackcrosstobasenji

BCSF2litter

CSBF2litter

AboriginaldogsofAfrica,Iraq,andAustralia

EarlyEnglishlandspanielsandhounds

Forcedtraining

Rewardtraining

Problem-solving:detourandmanipulationtests

Problem-solving:detourandmanipulationtests

MazetestandT-mazeanddelayed-responsetest

Trailingandspatial-orientationtests

FIGURES

1.1BasicMendeliancross/9

1.2Floorplanofnurseryroom/25

1.3Floorplanofall-weatherdogkennel/27

2.1GeographicaldistributionofwildmembersofgenusCanis/32

2.2Centersofdomesticationandadaptiveradiation/36

2.3Skullwidthacrosscheekbonesasrelatedtoskulllength/40

2.4Greatestwidthofupperjawrelativetoskulllength/41

2.5Sizeofmolarteethrelativetoskulllength/41

2.6Relativebreadthofupperjawinfivemodernbreeds/44

4.1Rateofdistressvocalizationduringfirst4weeks/92

4.2Developmentofwalkingandplayfulfighting/95

4.3Developmentofmotorabilityduringtransitionperiod/96

4.4Developmentoflearningcapacitiesduringneonatalandtransitionperiods/98

4.5Changeinresponsetoconditioningbetweentransitionandsocializationperiods/99

4.6Developmentofdistressvocalizationofbeaglepuppiesunder2conditionsofisolation/103

5.1Developmentoftheheartrate/121

5.2Effectofsocializationatdifferentagesuponavoidanceofanactivehandler/125

5.3Timingmechanismslimitingtheprocessofsocialization/126

5.4Performanceintheleash-controltest/127

tivLISTOFILLUSTRATIONS

5.5Eatingduringtheleash-controltest/128

5.6Avoidanceandvocalizationinresponsetohandling/134

5.7Avoidanceandfearfulbehaviorinresponsetohandling/135

5.8Agonisticbehavior(playfulfighting)inresponsetohandling/136

5.9Attractionandfollowinginresponsetohandling/138

5.10Et-epimeleticbehaviorandsocialinvestigationinresponsetohandling/138

6.1Percentageofoccurrenceofcompletedominanceinpurebredlitters/157

6.2Occurrenceoffightsorone-sidedattacksduringdominancetests/158

6.3Occurrenceofcompletedominanceinmale-femalepairs/160-62

6.4Declineofnursingbehaviorbymothersduringtheneonatalperiod/170

6.5Averagetimespentwithhandlerduringthefollowingtest/175

7.1Distributionofrunningtimes/188

7.2Distributionofmotivation-speedscores/189

8.1Totalreactivityratingsforthefivepurebreeds/198

9.1Proportionofanimalsratedasquietduringweighing/206

9.2Typesofdemeritsgivenduringleash-controltest/209

9.3Leveloftrainingonsuccessivedaysofobediencetest/213

9.4Meantimescoresongoal-orientationtest/217

9.5Proportionofanimalssucceedingoneachtrialofthemotor-skilltest/220

10.1Problemsinthebarriertest/227

10.2Resultsofthemanipulationtestonsuccessivedays/231

10.3Floorplanofthemazetest,left-handpattern/233

10.4Learningcurves:errorsinmazetest/235

10.5Learningcurves:timesofsolutionofmazetest/235

10.6Relativeperformanceofdifferentbreedsinthemaze/238

10.7T-mazeusedforcue-response,discrimination,anddelayed-responsetests/239

10.8Speedscoresincue-responsetest/240

10.9Apparatususedintheopatial-orientationtest/248

10.10Breedscoresonthespatial-orientationtest/252

10.11Individualerrorscoresonthespatial-orientationtest/252

10.12Inter-trialandintraclasscorrelationsinthespatial-orientationtest/255

11.1Distributionofscoresforplayfulfightingat13-15weeks/270

11.2Theoccurrenceofplayfulfightingtransformedtoascaleofthreshholdofstimulation/272

11.3Occurrenceofbarkingduringdominancetestsatdifferentages275

11.4Distributionofbarkingtoexcessinpurebreedsandhybridsat11weeks/277

I1.5Monthinwhichbreedingbeganinrelatedcockerspaniels/280

I1.5Monthinwhichbreedingbeganinrelatedcockerspaniels/280

1l.nIntervalsbetweenfirsttwoestrusperiods/281

11.7Proportionolcockersandbasenjisratedascompletelvquietduring

weighing2881isDevelopmentanddifferentiationofposturalresponses/289-9012.1Meanscoresofhybridsohsixmeasuresofleashtraining/300L2.2Meanmotivationspeedscoresofhybrids/307

Vttainmenlbyhybridsofcriterioninthecue-responsetest/308

12.4Attainmentbyhvbridsofcriterioninthedelayed-responsetest/310

12.5Meanscoresofhybridsontheobediencetest/311

12.6Meantotalreactivityscoresofhybridsat17,34,and51weeks/312

12.7Meanscoresofhybridsontworeactivitytestmeasures/314

12.8Proportionofeachhybridgroupratedas"high"intailwaggingat17,34,and51weeks/315

12.9Meancorrectchoicesscoresofhvbridsonthespatial-orientationtest/318

12.10Meanpersistencescoresofhybridsonthespatial-orientationtest/319

12.11Meanadjustedspeedscoresofhvbridsonthespatial-orientationtest/320

13.1Absoluteweightgainperweekinmalepuppiesofthelargestandsmallestbreeds/327

13.2Combinedgrowthcurveforbasenjimales/328

13.3Maleandfemalegrowthcurvesinbasenjisandcockerspaniels/330

13.4Growthcurvesofthefivepurebreeds/331

13.5Inheritanceofhairlength/335

13.6Distributionofdifferencesinstaninesbetweenlongandshort-coatedanimalsinrelationto34behavioralvariables/337

13.7Relativephvsicalproportionsofcockerspanielsandbasenjis/340

17.1Functionaldifferentiationofformduringgrowth/421

17.2Functionaldifferentiationofbehaviorinrelationtothephysicalenvironment/421

17.3Functionaldifferentiationofasocialrelationship/422

1.1Masterlistofexperimentalanimals/10

1.2Scheduleoffeeding,cleaning,anddiseaseprevention/14

1.3Scheduleofobservations,training,andtesting/24

2.1Averageskullmeasurementsofdifferentbreedsofdogs/43

2.2Ratiosofskullmeasurementstolengthofskull/44

2.3Coefficientsofinbreedingoffoundationstock/49

2.4HybridsreportedbetweenspeciesofthegenusCanis/53

3.1BehavioralsvstemsandknownbehavioralpatternsinthefamilyCanidae/63-65

4.1Timeofcompleteopeningoftheeye/90

4.2Timeoffirstfunctionoftheear/94

4.3Timeoferuptionofuppercanineteeth/96

4.4Timeofdevelopmentofallelomimeticbehavior/106

4.5Occurrenceofsexualbehaviorin160purebredpuppies(0-16weeksofage)/107

4.6Naturalperiodsofdevelopmentindogandman/114

5.1Estimatedvariationindevelopmentaleventsassociatedwiththebeginningoftheperiodsoftransitionandsocialization/120

5.2Relativeadjustmentofpuppiesat1yearofage/123

5.3Rankorderofpuppiesontestsgivenafter14weeksofage/128

5.4Developmentoftailwagging/139

6.1Socialrelationshipsofdogandman/153

6.2Effectofsizeondominance-subordinationrelationships/164

6.3Percentageofcompletedominanceinbasenjis,cockers,andtheirhvbridsat15weeks/166

6.4Occurrenceofmothersnursingpuppiesunder2weeksofage171

6.5Occurrenceofretrieving1-week-oldpuppiesbvpurebredandhvbridmothers/172

7.1Conversiontable—originalscoretostanine/189

7.2Simplifiedinterpretationofanalysisofvarianceinbreedcomparisonexperiment/192

8.1Specificresponseratings/197

8.2"Resting"heartrate/199

8.3Changeinheartrateduringquieting/199

8.4Meanstaninescoresoffivepurebreedsontenbehavioralandfourheartratemeasuresatthreeages/200

8.5Percentageofsubjectsexceedingarbitrarythresholdsoneightmeasuresinreactivitytest/202

9.1Meannumberofdemeritsinleashtraining/208

[ntercorrelarjonsoftypesofdemeritsduringleashtraining/2109.3Typesofdemeritsinearly,middle,andlatephasesofleash-controltest

211()1Meanstaninescoresonobedienceforpurebreeds/214

9.5Rankfivepurebreedsunderforcedtraining/215

9.6Correlationsbetweentestsofforcedtraining/216

9.7Percentageofanimalssuccessfullytrainedinretrievingtest/219

9.8Over-allperformanceonmotor-skilltest/221

10.1Performanceofthedifferentbreedsonthedetourtest—firsttrialsonly

229

10.2Percentageoftotalvarianceofmazescoresrelatedtobreed,mating,litter,andbackgroundvariables/236

10.3Attainmentofcriterionincue-responsetest/241

10.4Delaved-responseperformanceoffivepurebreeds/243

10.5Animalsshowingperfectperformanceonthefinaltrialofthetrailingtest/246

10.6Relativeranksofbreedsonperformanceonmostdifficulttrialoftrailingtest/246

10.7Distributionoffearreactionsintrailingtest/247

10.8Comparisonsbetweenpurebreedsonspatial-orientationscores/251

10.9Analysisofvarianceofspatial-orientationmeasures/253

10.10Ranksofthedifferentbreedsinvariousproblem-solvingtests/258

11.1ModificationsoftheCastle-Wrightformulafortheanalysisofquantitativeinheritance/264

11.2Theoreticalratiosforthedifferencesbetweenbackcrosses,F/s,andF2'scomparedtothedifferencebetweenparentalstrains/266

11.3Scoresforavoidanceandfearfulvocalizationat5weeksofageinresponsetoahumanhandler/267

11.4Tendencytobiteandjerktheleash/269

11.5Percentofanimalsbarkingperopportunity,comparedwithexpectedpercentage/276

11.6Percentofanimalsbarking19orfewertimesat11weeks/276

11.7Testsinvolvingpersistentdifferencesbetweenmaternallines/285

11.8Distributionofadultweightmeasurementsinbasenjis,cockers,andtheirhybrids/286

11.9Distributionofaverageheartrates,11-16weeks/287

12.1Leash-trainingdemeritsofhybrids/299

12.2Within-littervarianceofthefightingscoreofleashtraining/301

12.3Analysisofvariance—leash-fightingscoresofhybridsbymatingsandlitters/302

12.4Leash-controlfightingscore—offspringofF:siresbydifferentdams/302

12.5Leash-controlfightingscore—offspringofpurebreddamsbydifferentsires/303

12.6Analysisofvariance—fightingscoreinleashtraining/304

12.7Leash-controlvocalizationscore—offspringofsiresbydifferentdams/306

12.8Leash-controlvocalizationscore—offspringofdamsbydifferentsires/306

12.9Discriminationorcueresponse—analysisofvarianceofhybridperformance/309

12.10Analysisofvariance—totalreactivityscoresofhybrids/316

12.11Totalreactivityratings:meansofmatingsofpurebreddamsbypurebredsiresandFjsires/317

12.12MatingsofF^siresbypurebredandF^dams/317

xviiiLISTOFTABLES

13.1Percentageofadultweightreachedat16weeksofage/329

13.2Breedrankinbodymeasurementsrelativetoweight/342

13.3Significantcorrelationsbetweenphysicalmeasurementsandbehavioralvariablesinpurebreedsandhybrids/345

13.4FactorloadingsofphysicalvariablesinthecombinedF2population/346

13.5Factorloadingsoffactor1(generalsize)incombinedpurebreeds/348

13.6Factorloadingsoffactor1(generalsize)inShetlandsheepdogsandfoxterriers/349

14.1Compositionofcombinedpopulations/357

14.2Numberofvariablesinwhichthecombinedvarianceofsegregatingpopulationsexceedsthatofnon-segregatingpopulations/358

14.3Proportionofvarianceattributabletopopulationdifferences/360-61

14.4VariancecomponentsofeachselectedbackcrossandF2population/365

14.5MeanvariancecomponentsinvariablesshowingdifferencesbetweenthebackcrosseswithaP<.01/366

14.6Factor2(activity-success)inthecombinedF2generation/372

14.7Factor3(heart-rate)inthecombinedF2generation/372

14.8Factor2(reactivity)inthecombinedF1hybrids/374

14.9Correlationsofpoorperformanceonthetrailingtestwithperformanceinothertestsintwohybridpopulations/374

14.10CommonvarianceintrailingtestasindicatedbycorrelationwithperformanceinT-maze/377

16.1Mortalityrateper100birthsinpurebreedsandhybrids/40617.1Subdivisionsofgenetics/413

Subdivisionsofgenetics/413

THEDEVELOPMENT

OFBASIC

BEHAVIOR

PATTERNS

ASCHOOLFORDOGS

Formanyyearswehavehadpsychologistsandzoologistsworkingsidebysideinourbehaviorlaboratories.Whenwefirstbroughtthemtogether,weoftengotstereotypedreactionstoanynewdiscoveryinthefieldofbehavior.Azoologistwouldsay,"Whatawonderfulexampleofinstinct,"andapsychologistwouldcounter,"My,whataremarkableexampleoflearning!"Thishappenedoverandoveragainintheearlystagesofourwork,anditillustratestheconfusionwhichonceexisted,andmaystillpersist,regardingtheroleofheredityinrelationtobehavior.

Inthemoreremotepast,scientistssuchasJohnB.Watsontooktheviewthatheredityhadlittleimportanceandthatthebehaviorofahumaninfantcouldbemoldedinanydirectionbylearning.Others,followingSigmundFreud,heldthathumanbehaviorwasdeeplyrootedininstinctswhosesuppressioncouldresultinseriousmentaldisorders.Thevastmajorityofpsychologists,psychiatrists,andotherpracticalworkersinthefieldofhumanbehaviorhadnodefiniteinformationabouteithertherapidlydevelopingscienceofgeneticsorthewaysinwhichgeneticvariationcouldaffectbehaviordirectly.Norwastheclinicalobservationofhumanbehaviormuchhelp.True,manychildrenrearedinpoorfamilybackgroundslaterdevelopedinadequateandmaladjustedbehavior,butsomeofthemwereapparentlyunaffected,andstillothersworkedharderthanmostpeopletocompensatefortheirearlyexperience.Wastheirabilitytoriseaboveenvironmentduetoheredityortosomeunknowndifferenceinearly

aboveenvironmentduetoheredityortosomeunknowndifferenceinearlyexperience?

Thequestion"Whatdoeshereditydotobehavior?"isthereforeabasicone,boththeoreticallyandpractically.Therearemanydif-

BEHAVIORPATTERNS

ferentwaysoftryingtoanswerit.Onecaneithermakecomparisonsbetweenasmanyaspossibleofthemillionorsospeciesofanimalsintheworldorconcentrateonone,aswedid.Scientistsworkingwithbirdshavediscoveredmanystereotypedbehaviorpatternswhicharelargelyorganizedandgovernedbyheredity.Weourselveschoseamammal,partlybecausemammalsaremorecloselyrelatedtohumanbeingsthanarebirds,andpartlybecausethejobhadnotyetbeendone.Amongmammals,wechosethedogbecauseitshowsoneofthebasichereditarycharacteristicsofhumanbehavior:ahighdegreeofindividualvariability.Wereasonedthatiftherewereanyanimalmostlikelytoshowimportanteffectsofheredityonbehavior,itwasthedog,andthattheseeffectscouldbeassumedtobeatleastsomewhatsimilartothosewhichappearinhumanbeings.

Toputthisinmoreenthusiasticterms,thedogisaveritablegeneticgoldmine.Besidestheenormousdifferencesbetweenbreeds,allsortsofindividualdifferencesappearatthestrokeofthegeneticist'spickaxe,inthiscasethetechniqueofmatingtwocloselyrelatedanimals.Anyonewhowishestounderstandahumanbehaviortraitorhereditarydiseasecanusuallyfindthecorrespondingconditionindogswithverylittleeffort.Dogsaretimidorconfident,peacefuloraggressive,andmaybebornwithundershotjaws,clubfeet,orhemophilia(Dawson,1937;Burns,1952;Fuller,1960).

Althoughitistruethatadogisalarge,long-lived,andrelativelyexpensiveanimaltokeep,itisagooddealsmaller,shorter-lived,andlessexpensivethansomeothermammals.Dogsbreedmorerapidlythanprimatesoreventhecommonherdanimals,exceptforpigs.Dogscanpassthroughonecompletegenerationwithinayear.Amaturefemalecontinuestoreproduceforfivetosevenyears,bearingheryoungabouttwiceayearinlittersaveragingfourorfiveanimals.Nevertheless,itrequiresverycarefulplanningtogetthemaximumamountofinformationfromanexperimentwithdogs,andoneinitialmistakecanruinyearsofeffort.

Therefore,beforeourworkhadgonebeyondtheearlyplanningstage,weasked

Therefore,beforeourworkhadgonebeyondtheearlyplanningstage,weaskedanumberofleadinggeneticistsandpsychologistsintheUnitedStatestoattendaresearchplanningconferenceatBarHarbor.Manyofthesemenandwomenweredoingrelatedresearch,eitheronanimalsoronpeople.ThechairmanwasDr.RobertM.Yerkes,oneofthepioneerworkersonheredityandbehavior,thefounderoftheYerkesLaboratoryofPrimateBiology,andatthattimetherecognizeddeanofanimalbehavioristsintheUnitedStates.Equallydistinguishedworkersmadeuptherestof

SCHOOLFORDOGS5

thegroup.Dr.FrankBeachservedassecretary,organizingtheproceedingsintoacoherentwhole.ForthreedayswemetwiththemonMountDesertIslandanddiscussedthedirectionwhichtheresearchshouldtake.Muchofourfinalplanresultedfromthisconference(ScottandBeach,1947).

Atthestartwehadcertainguidingprinciplesandsignpostsderivedfromwhathadbeendiscoveredaboutotheraspectsofheredity.Weknewthatbehavioritselfisnotinherited.Infact,theonlythingswhicharebiologicallyinheritedfromtheparentsaretheeggandsperm.Wealsoknewthatthebasicfactorsofheredityaregenes,whicharenothingmorethanlargeorganicmoleculesarrangedinlargerbodiescalledchromosomes.Eventheseareonlypartsofthenucleusofalivingcell.Thegenesthemselvescanactonlybycontrollingthesynthesisofproteins,someofwhich,theenzymes,modifyotherchemicalorphysiologicalreactions,usuallyinthecellsthemselves.Allthisisalongwayfromtheactivityofawholeorganism,orbehavior,andtheconcretefactofwhetheradogbitesyouorwagsitstail.

Oneoftheprimaryquestionswehadtoanswerwaswhetherhereditycouldproduceanimportanteffectuponbehaviorinahigheranimalorwhetheritsimplysetthestageforbehavioralactivitywhichwasthenguidedandmoldedbyothercauses.Thequestionmakesagreatdealofsenseinrelationtotheconceptoflevelsoforganization(seeTable17.1).Hereditystandsatthemostbasiclevel,andthereforewecanassumeittobeveryimportant.Butassumptionsareonlythebeginningofscientificinquiry,andthequestionstillremains,Whatexactlycanafactoroperatingonalowleveloforganizationdotoaphenomenonoperatingonahigherlevel?Forbehaviorisprimarilyaphenomenonexistingontheor-ganismicorpsychologicallevel(Wright,1953).

Atthesametimewerealizedthatwecouldnotneglectfactorsoperatingonstill

Atthesametimewerealizedthatwecouldnotneglectfactorsoperatingonstillotherlevels.Amajortrendinanimalbehaviorresearchinthelastthirtyyearshasbeentodemonstratetheimportanceoftheeffectsofsocialorganizationuponbehavior.Theactivityofanindividualisunderstandableonlyintermsofhisrelationshipstothemembersofalargergroup.Ourworkwasthereforedesignedinrelationtolevelsoforganizationandcanbesodescribed.

Inaddition,wehadthesuccessesandmistakesofourpredecessorstoguideus.ProfessorTryon(1930-41,1963)ofthePsychologyDepartmentoftheUniversityofCaliforniahadpreviouslydoneextensiveandmeticulousresearchonheredityandbehaviorinrats.

BEHAVIORPATTERNS

Hedevisedamechanicalmazeoperatinginsuchawaythattheexperimentercouldnotinfluencetheresultsconsciouslyorunconsciouslyandselecteddifferentstrainsofratsfromthosewhichlearnedthemazemostquicklyorslowly.Thesedifferencespersistedforgenerationaftergeneration,indicatingthathereditycouldproduceanimportanteffectuponbehavior.Itappearedthatselectionhadaffectedintelligencealone,butwhenastudentofhis,Searle(1949),testedtheseratsondifferentsortsofmazes,hecametotheconclusionthatoneoftheprincipalreasonswhythetwostrainsofratsdifferedinperformancewasthattheslowrunningor"dull"ratswereafraidofthemechanicalmaze.Insteadofselectingpurelyforintellectualability,Tryonhadalsoselectedforadifferenceinemotionalreaction.

C.S.Hall(1941)hadshownbyhisselectionexperimentsonthedefecationratesofratstakenfromtheircagesandplacedinanopenspacethathereditycouldalteranotherkindofemotionality.Hiswork,andthatofSearle,suggestedthatemotionalcapacitieswerehighlyvariableandcouldproduceimportanteffectsuponperformance.Fromthesepreviousexperimentsweknewthathereditaryemotionaldifferencesmighthaveimportanteffectsonbehaviorwhichatfirstglancedidnotappeartobeemotional.Wealsorealizedthatwithsuchalong-livedandexpensiveanimalasthedog,wewouldseldombeabletoduplicateourexperiments.Inotherwords,therewouldbeverylittlegoingbacktotakeasecondlook.Wewouldhavetomeasureasmanyimportantcharacteristicsaswecouldwhiletheexperimentwasinprogress.

Besidestheworkonotheranimals,therehadbeenanearliermajorattempttoworkwithheredityindogs.ThelateProfessorC.R.StockardoftheCornellUniversityMedicalSchoolhadbegunwiththeidea(apromisingoneatthetime)

UniversityMedicalSchoolhadbegunwiththeidea(apromisingoneatthetime)thatmanyofthedifferencesbetweenbreedsofdogswerecausedbyhereditarydisordersintheductlessglands(1941).Hedid,indeed,findbreeddifferencesintheendocrineglands,butanatomicalpeculiaritiesinthesamebreeds,suchasdwarfismandshortleggedness,turnedoutnottobecausedbyglandsbutbyhereditaryfactorsworkinginotherways.ProfessorStockarddiedbeforehecouldchangetheprojecttoallowforthis.SincehisoriginalexperimentwasnotdesignedtotestaMendelianhypothesis,theresultswereinconclusive,andwedecidedtosetupourexperimentinthebroadestpossibleway,realizingthatwecouldnotpredicttheimportantresultsinadvanceandthatitwechosetoonarrowanapproachwemightendwithnoth-

SCHOOLFORDOGS7

ing.Bothfromthisviewpointandthesimplestatisticsoflifeinsurancetables,weknewitwasimperativethatthisprojectbeacooperativeventure,notaone-manshow,andinthisbookweshalltrytorecognizetheinnumerablecontributionsmadebyco-operatorsandco-workersintheyearscoveredbytheexperiment.

Ourover-allexperimentaldesignwastosystematicallyvarythegeneticconstitutionofthedogswhilekeepingallotherfactorsasconstantaspossible.Thedependentvariablewasbehavior,butsincebehavioroccursonlyinreactiontostimulation,wehadnotonlytheproblemofdesigningauniformsystemoftestsituationswhichwouldmeasurethedog'sreactionstospecifiedchangesinhissocialandphysicalenvironment,butalsothatofkeepingallotherenvironmentalfactorsasconstantaspossible.Equallyimportantwasthetaskofkeepingthedog'sinternalenvironmentconstantbyseeingthateachanimalwasadequatelynourishedandfreeofdisease.

GENETICMETHODS

Choiceofbreeds.—Geneticvariationwastheprimaryvariableinourexperiment:thesupposedcausewhichmightormightnotaffectbehavior.Wethereforedividedtheexperimentintotwophases.Inthefirstwemadeasurveyofthedifferentdogbreedsinordertoselectthosewhichshowedthebiggestbehavioraldifferences.ThankstotheenergyofDr.C.C.Little,wehadawidevarietyfromwhichtochoose,rangingfromtheGreatPyrenees,awhitedogroughlyresemblingaSaintBernard,tothetinyChihuahuas.Wesooneliminatedtheabnormalsizesatbothendsofthescale,realizingthatthelargebreedsweretooexpensiveforlongexperimentsandthatthetoyordwarfbreedswere

tooexpensiveforlongexperimentsandthatthetoyordwarfbreedswereunsuitablebecauseoftheirlowfertility.Furthermore,ifwechosedogsofapproximatelythesamesize,wecouldusethesameapparatusforall.

Certainbreedswerediscardedearly.BothdachshundsandScottishterriershaveareputationforbeingstubbornandself-willed,butthosewestudiedsnowednotraceofthisaspuppies,beinguniformlyfriendlyanddemonstrativeanimals,notunlikebeaglesandcockersinthisrespect.Wewouldobviouslyhavetowaittoolongforthebehavioralpeculiaritiesofthesebreedstodevelop.

Wefurtherdecidedtoconcentrateonbreedswithnormalphysique.Althoughitistruethattheshortleggednessofthedachshund,forexample,hasaneffectuponitsbehavior,thisdoesnotrequire

8BEHAVIORPATTERNS

anelaboratescientificexperimentforproof.Wepreferredtoworkwiththemoresubtleandperhapsmoreimportantwaysinwhichheredityaffectsbehavior.

Wefinallyselectedfivebreedsforintensivestudy:basenjis,beagles,Americancockerspaniels,Shetlandsheepdogs(shelties),andwire-hairedfoxterriers.Asitturnedout,thesewererepresentativesofthemajorgroupsofdogsasrecognizedbydogbreedersandomittedonlythetoyandnon-sportingbreeds.

Inthefirstphaseintheexperiment,wedevelopedourtestsandraisedallfivebreedsinthesameenvironment,measuringtheirsimilaritiesanddifferences.Wealsostudiedthedevelopmentoftheirbehaviorbymakingdailyobservationsfrombirthupto16weeksofage.Whereverpossible,wecross-fosteredpuppiesbetweenthebreedsinanefforttoseewhetherthematernalenvironmentaswellasbiologicalhereditywasaffectingbehavior.Wealsoexperimentedwithanevenmoredrasticshiftinthesocialenvironmentbytakingcertainpuppiesoutofthekennelsandrearingtheminhomes.Thisnotonlygaveusachancetostudytheeffectofmaternalenvironment,buttoseewhetherornotourkennel-reareddogswerereasonablynormalcomparedtodogsrearedoutside.Unfortunately,wewereabletodothisonlyonaveryfewanimals,partlybecauseofthelimitednumberoffriendsandfellowworkersonwhomwecouldimpose,andpartlybecauseofthedangerofdiseasetransmission.Anticipatingalittle,wecansaythatGyp,thebasenji;George,thebeagle;andSilver,theShetlandsheepdog,didnotdostrikinglybetterorworseonmostofthetests,althoughtheydevelopedverydifferentrelationshipswithdogsandpeople.

AMendeliancross.—ThesecondphaseoftheexperimentwastomakeaMendeliancrossbetweentwoofthebreeds(Fig.1.1).PreliminaryresultsindicatedthattheAmericancockerspanielandtheAfricanbasenjishowedagreatmanydifferencesinbehavior.Ontheonehandwehadagentleandpamperedhousepetdescendedfrombirddogs,andontheotherabreedwhichhadrecentlycomefromtherough-and-tumbleconditionsofAfricanvillagelife.Furthermore,therewasgoodevidencethatthebasenjis,havingbeenfirstbroughtoverfromAfricain1937,hadneverbeencrossedwiththeEuropeanbreeds,whereasthecocker(aswellastheotherthree)hadoriginallycomefromtheBritishIsles,wheretherehadbeenabundantopportunityforcrossinginthepastandconsiderablehistoricalevidencethatthishadactuallytakenplace.Thesetwobreedshadbeenmadegeneticallydifferentbyisolationaswellasbyselection.

SCHOOLFORDOGS9

Wedidnotattempttoaccentuatethedifferencesbetweenthebreedsbyfurtherselection,asthiswouldhavebeenaten-yearprograminitself.Instead,wedecidedtorelyontheselectionwhichthepracticaldogbreedershadalreadydoneoveraperiodofcenturies.Thisselection,however,hasnotproducedcompleteuniformity.Inmostcasesthebreedstandardspermitconsiderablevariation,eveninsuchobviouscharacteristicsascolor,andwehadalreadyfoundthattherewasagreatdealofvariationbetweenbothindividualsandstrainswithinthepurebreeds.Inordertolimitthiskindofvariation,wedecidedtomakeallourcrossesfromtheoffspringofasinglepairofanimalsineachbreed.Thiswouldlimitthegeneticvariabilityintheparentstothatwhichhadexistedinasinglebrother-sisterpairratherthanthatwhichwascharacteristic

CS?,CockerSpanielXBA<?,BasenjiCSa*,CockerSpaniel,XBA$,Basenji

L

-X—BCSF,<?XBCSR?CSB?XCSB<?~X'

11II

BCSXCSBCSF2CSBF2CSBXBA

BACKCROSSTOCOCKERBACKCROSSTOBASENJI

BCSCROSSCSBCROSS

Fig.1.1.—DiagramofMendeliancrosswithsymbolsusedfordifferentgeneticpopulations.Thebasicplanwastorepeateachofthetwocrosseswithfourmatingsandobtaintwolittersfromeachmating.Becauseofdeathsamongthecockerspanielfemales,replicationwascompletedonlythreetimesintheBCScross(seeTable1.1).

oftheentirebreed.Wewereabletocarryoutthisplansuccessfullywiththebasenjis,butinthecaseofthecockerswewerenotabletoobtainenoughmalesfromasinglematingattherighttimeandhadtomodifyourplanslightlybyusingasourfoundationstockanimalsfromtwocloselyrelatedmatingsinwhichthesamemalewasmatedtohissisterandmother.

Inordertocontrolforthepossibleeffectsofthematernalenvironmentandalsotodemonstratesex-linkedinheritanceifitshouldexist,wemadereciprocalcrosses.Theidealplanwastomatefourbasenjimaleswithfourcockerfemalesandviceversa.ThiswouldgiveustwoFipopulations,onefromcockermothersandonefrombasenjimothers.Thenwetookafirstgenerationmalefromeachmatingandcrossedhimbacktohismother.Inthiswaywecouldcomparetwosetsofoffspringofthesamemother.Inthebackcross

BEHAVIORPATTERNS

groupweexpectedthatthegeneswouldbeassortingandrecombin-ingindifferentcombinationsaccordingtothelawsofMendelianinheritance,whereasintheFigenerationallanimalswouldreceivethesameinheritanceandbemuchlessvariable.ThenwetookthesameFimalesandmatedthemtotheirsistersinordertoproduceanF2generationinwhichthemaximumgeneticvariabilitywould

occur.

Weanticipatedthatwewouldbeabletostudytheeffectsofhereditychieflyfromthevariabilityofbehavior,andwethereforeplannedtoraiseatleasttwenty-fivetothirtyanimalsineachpopulation,thisbeingthesmallestnumberinwhichareasonablyaccuratesampleofapopulationdistributedinanormal

inwhichareasonablyaccuratesampleofapopulationdistributedinanormalcurvecanbeobtained.Thesearenotlargenumbersforgeneticdata;ifwehadbeenworkingwithfruitflies,forexample,wewouldhavepreferredtoobtainatleastahundredineachgroup.Therefore,wemadeanefforttogetanunusuallylargenumberofF2*s,themostcrucialpopulationforalltypesofgeneticanalysis.Furthermore,weplannedtoobtainatleasttwolittersofpuppiesfromeachmating,sothatwecouldcomparevariationinsiblingswhichwerelittermatesandsiblingswhichwerenot.

table1.1MasterListofExperimentalAnimals*andKeytoBreeds

BreedorHybrid,andSymbol

Basenji(BAorB)

Beagle(BEA)

Cockerspaniel(CS)

ShetlandsheepdogorSheltie(SH)

Wire-hairedfoxterrier(\VH)

F,BAd"XCS9(BCS)

F.CSd"XBA9(CSB)

BackcrosstoCS(BCSXCS)

BackcrosstoBA(CSBXB)

F2fromBCS(BCSXBCS)

F2fromCSB(CSBXCSB)

All

•Includesallanimalsuponwhichsomeexperimentalworkwasdoneandwhichlivedatleastto16weeks.

Thedatacouldbeanalyzedinanumberofways.Analysisofvariancewouldmeasurethechangesinvariationproducedbygeneticsegregation,by

measurethechangesinvariationproducedbygeneticsegregation,bydifferencesintheenvironmentproducedbydifferentmothers,andbytheaccidentofbeingbornatdifferenttimestothesamemother.Correlationalanalysiswouldrevealthe

extenttowhichcloserelativesresembledeachother,aswellastheresemblancebetweendifferentkindsofbehavioraltests.Inaddition,wecouldanalyzetheeffectofphysicaltraitsonbehaviorbycalculatingthecorrelationsbetweenbodymeasurementsandpsychologicalmeasurements.Wecouldalsodeterminewhetherornottheexternalcolorfactorswereassociatedwithbehavioraldifferences.Forexample,theownersofcockershaveoftenallegedthattheredsandblackshavedifferenttemperaments.

Lookingbackontheexperiment,wenowseehowwemighthaveorganizeditinabetterfashion.Weshouldhaveallowedforalargernumberofsparematings,asaccidentsanddeathswilloccureveninthebestregulatedlaboratories.Inaddition,wehadplannedtheexperimentwiththeanticipationthatmostofthetraitswouldshowmultiple-factorinheritance.Surprisingly,wefoundthatmanyofthebreeddifferencescouldbeexplainedintermsofsimpleone-andtwo-factorinheritance.Ifwehadtheexperimenttodoagain,wewouldemphasizethebackcrosses,makingasecondbackcrosstothepurebreedsineachcase,thisbeingacriticaltestforsingle-factorinheritance.WealsofoundthatourFifemalesbecamemuchsuperiormotherscomparedtothepurebredanimals,producinglargequantitiesofmilkandgivingexcellentcaretotheiroffspring,sothattheF2'shadabetterstartinlife.ThesegeneticandenvironmentaladvantagesoftheFi'sandF2'sarereflectedindecreasedmortality(Table16.1).Itwouldhavebeeninterestingtohavemadeback-crossestothepurebreedsfromtheFifemalesaswellasfromthemalesinordertodeterminetheeffectofsuperiorearlyenvironmentonthesamegenetictypes.

Stillanotherunanticipatedresultwasthelargeamountofvariationbetweenlitters.Littermatestendtobealike,and,inananimalwhichrearsitsyounginlitters,thebestunitofthepopulationisnottheindividualbutthelitter.Itwouldhavebeendesirabletohavehadmorelittersthanwedid.However,allthiswouldprobablyhavetakentwenty-fiveorthirtyyearstocompleteinsteadofthirteen.

THEINTERNALENVIRONMENT:CONTROLOFNUTRITIONANDDISEASE

Feeding.—Sincegeneticswasourchiefexperimentalvariable,weattemptedto

Feeding.—Sincegeneticswasourchiefexperimentalvariable,weattemptedtokeepphysiologicalfactorsasconstantaspossible.Oneoftheseisthestateofnutrition,and,aswehaveseen,thisispartlydependentuponthemotherandhenceuponherheredity.Therewasnowayinwhichwecouldforcethemotherstoproduceaconstant

12BEHAVIORPATTERNS

amountofmilk,butinallotherwayswecouldprovideauniformdiet.

Whenwebegantheexperimentin1945,meatsofanykindweredecidedlyvariableinsupply.However,onepreparedanimalfoodwithaguaranteedconstantformulawasreadilyavailable.ThisfoodwasPurinaLaboratoryChow,andwedecidedtomakeitthebasiciteminthediet,keepingitconstantlyavailableinametalfeeder.Itwasnotaperfectfoodfordogs,asithadbeendevelopedasanall-purposelaboratoryfoodforrats,mice,guineapigs,andmonkeysaswellasdogs.Itcontainedmoreroughageandlessfatthanwasideallysuitablefordogs.Itproved,however,tobeanintrinsicallysounddiet,asourexperimentalanimalsdevelopedintohealthyandvigorousadultswitheveryindicationthattheirgrowthwasequaltonormalbreedstandardsorbetter(seeChap.13).

Theyoungpuppiesandnursingmothershadtohavesupplementaryfood,andthiswaskeptassimpleaspossible.Onenaturalfoodwhichisextraordinarilyconstantincompositionismilk,andthiswastheprincipalsupplement.Weusedcannedmilkatfirst,butlaterswitchedtopowderedwholemilkbecauseofitslowercost.Tothisweaddedavitaminsupplement,Abbott'sHaliverMalt,inordertoprovideasourceofvitaminsAandD,whicharethosemostlikelytobelostfromtheagingofdrypreparedfoods.WealsohadavailableatalltimesforthepuppiesandmothersdryPurinaKibbledMeal,mostofwhichwasafinepowderwhichtheyoungpuppiesbegantoeatassoonastheywereable.ThisfooddidnothavethestandardizedformulaoftheLaboratoryChowbutwasdesignedprimarilyasadogfoodandwassuperiortoitinthatrespect.

Thedogsconsequentlyhadbeforethemaconstantsupplyofdryfoodwhichtheycouldeatatanytime.Thisreducedthelaborofcaringfortheanimalsbutalsohadanotherpurpose.Wewishedtoraisethepuppiesinnaturalsocialgroupsandkeptthemtogetherintheirlittersratherthanrearingthemasisolatedindividuals.Ifallowedtocompeteforfood,asfrequentlyhappenswithdishesofmeatorwetmash,unequalnutritionwouldsoonresult.Asitturnedout,puppiesinalitterdidnotcompeteforthemilk,asdogsneverappeartofightforaliquid,

inalitterdidnotcompeteforthemilk,asdogsneverappeartofightforaliquid,andtheyrarelyshowedanydispositiontoquarreloverthedryfood.Inanycase,nodogcouldkeepguardoverthedryfoodeveryminuteofthedayinalargepen.

Inmanypsychologicalexperimentsweusedafoodreward,asmallspoonfulofcannedherringhavingastrongfishyflavorsimilartosardines.Thedogsseemedtorelishthesetidbits,andtheamountstakenwerenotlargeenoughtodisturbtheirnutrition.

Sanitation.—Oursecondconcernwastokeeptheanimalshealthyandfreefromdiseaseatalltimes.Thefirstproblemwassanitation.Manykennelsmaintaintheirdogsonbarefloorsandwashthesedaily.However,thismeansthatthefloorsareconstantlywet,dogsandattendantsfrequentlystepinfeces,andthereisaconstantstrongodor.Sinceourexperimentalcrewhadtoworkwiththedogsinthepens,wehadtoconsiderthecomfortofboth.Wedecidedtocoverthefloorsofthepenswithwoodshavingswhichabsorbmoisturefromurineandfeces.Thisproducedsweet-smellingroomsinwhichbothdogsandattendantscouldeasilykeepthemselvesclean.Feceswerepickeduponceadayaftertheanimalswerefed,leavingtheroomrelativelycleanfortherestoftheday.This,ofcourse,didnotsubstituteforthoroughcleaning,whichnecessitatedmovingthedogsfromthepens,removingtheshavings,andsteam-cleaningthefloorsandwalls.Wewishedtoavoiddisturbingpuppiesatcriticaltimesofdevelopmentandatthesametimetogivethemalluniformtreatment.Thepenswerethereforethoroughlycleanedonceeveryfourweeksafterthepuppieswereborn.Thissystemwasacompromisebetweencompletesanitationandpsychologicaldisturbance,butworkedreasonablywell.

Diseasecontrol.—Themostcommondangerousdiseaseforyoungpuppiesiscausedbyintestinalroundwormswhichcanmakeayoungpuppyseriouslyillorevenkillhim.Itisalmostimpossibletoabolishtheseparasitescompletely,astheycanbepassedalongtothepuppiesbythemotherevenbeforebirth.Wethereforesetuparoutinesystemofworming(seeTable1.2)forallpuppies,whetherornottheywereinfected,sothateverypuppywouldhavethesametypeofexperienceandthesamechancesforgoodhealth.Wormingwascorrelatedwiththecleaningschedule,sothatpuppieswerewormedat4and8weeks,beforebeingputbackintoacleanpen,andagainat16weeks,whentheyweretransferredtoanewpen.

Cleaningandhealthactivitieswerethusorganizedarounda4-weekunit,and

Cleaningandhealthactivitieswerethusorganizedarounda4-weekunit,andthisscheduleresultedinthedevelopmentofa4-weekmoduleforplanningthesocialexperienceofthepuppies.Thiswaslateramplifiedandextendedinthepsychologicaltestingprocedure.

Thesecondmajorthreattohealthwascaninedistemper.Thisisahighlyinfectious,airbornediseasewhichattackstherespiratoryandnervoussystemandproduces50-or60-percentfatalities,whileexposingeventhesurvivorstoalingeringillnessandprolongedconvalescence.Itspreventionissoimportantthatinthisonerespectwedeliberatelydepartedfromouridealofuniformconditions

14BEHAVIORPATTERNS

TABLE1.2ScheduleofFeeding,Cleaning,andDiseasePreventionforPuppies

Age(weeks)

Food

Cleaning

DiseasePrevention*

45678

91011121314151617-52

Mother'sMilkonlyuntil3weeks

Cow'sMilk&HaliverMalt,KibbledMeal,LaboratoryChowadded

Motherremoved

LaboratoryChowonly

Dailycleaning(continuedthrough52weeks)

Steamcleaning

Steamcleaning

Steamcleaning

SteamcleaningDailycleaningonly(movedtooutsiderun)

Worming,Spratt'sCapsules

Worming,N-butylchlorideAnti-distemperserum

Anti-distemperserum

Killeddistempervirus

Livedistempervirus

Worming,N-butylchloride

Latermodified.Seetext.

throughouttheentirecourseoftheexperiment.Atthetimewestarted,thebestsystemofpreventionconsistedofaseriesofthreeinjections,twoweeksapart.Thefirsttwoinjectionsconsistedofakilledviruswhichproducedapartialimmunity.Inthefinalone,thelivevirusproducedapermanentimmunity.Althoughnodogsdiedafterthistreatment,manyofthembecameillfromtheinjectionofthelivevirus,andthisinterferedwiththeirbehavioraltests.Wethereforeabandonedtheuseofthelivevirus.InthemeantimetheLederleCompanyhaddevelopedanavianizedlivevirus,oneinjectionofwhichcouldproducepermanentimmunitywithoutanysignsofillness,andweswitchedtothissystem.Bothmethodswereputtoanactualtestbytheaccidentalintroductionofadogwithlatentdistemperintothecolony.Everyanimalwhichwasnotcompletelyprotectedcamedownwiththedisease,includingmostofthosedogswhichhadreceivedonlytheinjectionsofthekilledvirusandaFewotchosewhichhadbeenprotectedbysingleinjectionsofavianized\irus.Allresearchcametoastandstillforsixmonthswhilethediseasewasbroughtundercontrol.Asaresultofthisexperience,anewsystemwassetup.Beginningat8weeksofage,thetimewhen

mostpuppiesbegintolosetheimmunityacquiredbvnursingfromimmunemothers(Bakeretal,1959),thepuppiesweregiventemporaryimmunitythroughseruminjectionsandatthesametimegiventheavianizedvaccine.Twoweekslaterthevaccinewasreinjected,incasethefirstdidnottake.Thewholecolonyofadultswasreinjectedeven'twoyearsoroftenerinordertomaintainimmunity,withcompletelyeffectiveresultsthroughouttherestoftheexperiment.Thissupersafesystemcouldnothavebeencarriedoutwithoutthe

experiment.Thissupersafesystemcouldnothavebeencarriedoutwithouttheco-operationoftheLederleCompany,whichgenerouslycontributedthenecessaryveterinarysupplies.

Anotherhighlyfataldiseaseindogsisinfectioushepatitis.Itisspreadthroughurineratherthanairandhencedoesnotdiffuseasrapidlyasdistemper.However,itprovidesarealthreattoadogcolonybecauseanindividualwhichrecoversmaybeacarrierandkeepspreadingthediseaseforyearsafterward.Injectionsofthekilledvirusresponsibleforthisdiseasewerelateraddedtothedistemperinjections,providingimmunityforapproximatelysixmonths.Thishadtobemaintainedbyrepeatedinjections.Atthepresenttimeapermanenttypeofvaccinecombinedwiththedistempervaccineisavailableandisusedinourcolonv.

Tomakesurethatreasonablyuniformphysiologicalconditionswerebeingmaintainedforthepuppies,weweighedthemonceaweek,beginningatbirthandcontinuingthrough16weeks.Inayounganimal,continuedgrowthisthebestindicationofgoodhealth,andfailuretogainisoftenthefirstindicationthatallisnotwell.Inaddition,wecountedtheheartrateswithastethoscope.Thismeasureturnedouttobeanimportantindicationofprobablesurvivalinnewbornpuppies.Thosewithaslowheartrateusuallydidnotsurvivemorethanadayorso.Theheartratealsobecameanimportantindirectmeasureofbehavioraldevelopment,beingstronglycorrelatedwithmajorchangesinbehavior.Theweeklyweighings,besidesfunctioningasacheckonhealth,gaveusanopportunitytomakevariousbehavioralobservationsupondevelopmentandtomakesurethatthepuppiesweretrulynormalintheirsensoryandmotorcapacities.

THEOBSERVATIONOFDEVELOPMENT

Fromtheveryfirstitwasobviousthatourpuppieswerechangingfromdaytodayandweektoweek,andthatwhiletheheredityofasinglepuppyremainedconstant,itwasactinguponaverydifferentanimalatbirththanafewweekslater.Wethereforebeganregular

16BEHAVIORPATTERNS

dailyobservationsofourpuppies,startingatbirthandcontinuingupto16weeksofage,hopingtoobservetheveryearliestmanifestationsofhereditarydifferences.Wealsohopedthatwemightinthiswayseetheactionofhereditypureandundefiled,beforeitbecamecontaminatedwiththeeffectsof

pureandundefiled,beforeitbecamecontaminatedwiththeeffectsofexperience.

Themethodwassimple.Eachdayatrainedobserverwatchedthepuppiesfor10minutesthroughthewindowsofthenurseryroomsandwrotedowneverythingtheydid.Onthebasisofourfirstobservations,wecompiledachecklistonwhichtheearliestappearanceofvariousbehaviorpatternscouldberecorded.Duringthefirsttwoweeksafterthebirthofalitter,theobserverwentintothepenandsatquietlybythenestboxinordertoseethepuppiesmoreclosely.Afterthistime,whentheeyeswereopenandthepuppieswerelikelytorespondtotheobserver,theobservationsweremadefromoutsidetheroom.Observationswerealwaysmadeinthemorning,closetothetimewhenthemotherswerebeingfedandthepenscleaned,asthiswasthetimewhenthepuppieswerelikelytobemostactive.Atothertimesoftheday,theentirelittermightbeasleepduringthewhole10-minuteperiod.Afterthepuppieshadbecome10weeksoldandweremuchmoreactiveandshowedfewerchangesfromdaytoday,theobservationperiodwasreducedto5minutes,duringwhichtimeasmuchormoreactivitycouldberecordedasbefore.

Theresultswerequiteunexpectedbutscientificallyexciting.Duringtheveryearlystagesofdevelopmenttherewassolittlebehaviorobservedthattherewaslittleopportunityforgeneticdifferencestobeexpressed.Whenthecomplexpatternsofbehaviordidappear,theydidnotshowpureanduncontaminatedeffectsofheredity.Instead,theywereextraordinarilyvariablewithinanindividualandsurprisinglysimilarbetweenindividuals.Inshort,theevidencesupportedtheconclusionthatgeneticdifferencesinbehaviordonotappearallatonceearlyindevelopment,tobemodifiedbylaterexperience,butarethemselvesdevelopedundertheinfluenceofenvironmentalfactorsandmayappearinfullfloweronlyrelativelylateinlife.

Morethanthis,wesoonrealizedthatweweredealingwitharemarkableseriesofdevelopmentalchanges;thatthepuppycomesintotheworldnotasasimplifiedversionofanadultbutasananimalhighlyadaptedtoaninfantileexistence,andthathelaterundergoesatransformationinbehaviorwhichisalmostasspectacularasthemetamorphosisofthetadpoleintoafrog.

Thustheconceptofdevelopmentbecameaveryimportantonein

interpretingourresults,bothinrelationtothedevelopmentofsocialrelationshipsandinrespecttotheincreaseincapacityforpsychologicalperformance.Theconceptofdevelopmentalchangetowardincreasing

performance.Theconceptofdevelopmentalchangetowardincreasingcomplexityoforganizationtiestogethertheactionofthemanyfactorswhichaffectbehavioronalllevelsoforganization.Forexample,geneticsdoesnotactinstantaneouslybutmustworkthroughphysiologyoverlongperiodsoftimeinordertoaffectbehavior.Likewise,apuppyisbornwithoutexperienceoftheoutsideworld,andhisbehaviorisorganizedandreorganizedinrelationtothesocialandphysicalenvironmentsthroughouthislifetime.Allthesefactorscontinuallyacttogetheranduponeachothertoproducethecapacitytoreacteffectivelytoeachnewenvironmentalsituationthroughoutlife.

THESOCIALENVIRONMENT:TESTSOFSOCIALBEHAVIOR

Controllingthesocialenvironment.—Ourobservationsofdevelopmenthadshownusthatthe4-weekmoduledidnotcoincidewithimportantchangesinsocialdevelopment.Amajorchangeinbehaviortakesplaceatabout3weeksofage,whenthesenseorgansfirstbecomecompletelyfunctionalandthepuppybeginstoformitsprimarysocialrelationshipsandtoeatsolidfood.Anotherbasicsocialchangeisweaning,whichmayoccurnaturallyasearlyas7weeks.Wedecidedtokeepthemotherswiththepuppiesuntil10weekssothattheseparationwouldnotcoincidewiththecleaningandfeedingschedule.

Wealsohadtodecidewhentomovethepuppiestothelargeoutdoorpens.Wechose16weeks,primarilybecausethiswasatimewhenallthepuppiesweresufficientlydevelopedphysicallytobeabletostandthechangetooutdoorconditionsatanytimeofyear.Fromsomeotherviewpoints,thiswasnotanidealtime.Manyofthedogswerejustgettingtheirsecondteethandmayhavehadsomedifficultyinhandlingsolidfood.Laterobservationsonpuppiesraisedinlargeone-acrepensindicatedthattheystayedveryclosetothekennelor"den"untilabout12weeksofage,afterwhichtheybegantowandermorewidely.TheexperienceofC.J.Pfaffenberger(1963)withguidedogsindicatedthatpuppieskeptinkennelsbeyond14weeksalreadybegintoshowtheusualdeleteriouseffectsofprolongedkennelrearing:timidityandlackofconfidence.Theidealtimetomovethepuppiesoutdoorswouldprobablyhavebeenbetween12and14weeks.However,sinceallanimalsweretreated

18BEHAVIORPATTERNS

alikeinthisrespect,thelaterdatedidnotaffectthebehavioralcomparisons.

Afewexceptionsweremadetothisplan.Whenfemalescameintoestrusbefore

Afewexceptionsweremadetothisplan.Whenfemalescameintoestrusbeforeayearofage,theyweretemporarilyremovedfromtheirlittersandhousedtogetherinaseparatepen.Inthefoxterrierlitters,groupattacksoncertainindividualsmadeitnecessarytoremovethevictims.Sometimesthelitterwasdivided,andinothercasesasingleanimalwastransferredtoagroupofmorepeacefulanimalsofthesameagebutadifferentbreed.

Testsofsocialrelationships.—Duringthefirstfewweeksthepuppiesstayedwiththeirmotherandlittermatesintheirnurseryrooms.Onceadaythecaretakercameintofeedandwaterthemotherandtocleantheroom.Onceaweekapairofexperimenterscameinfortheweeklyweighing.Otherwisethepuppieshadnocontactwithhumanbeings.Whentheyreached5weeksofage,wefirstbegantodevelopandmeasuretheirsocialrelationships.Thefirstprocedurewasahandlingtest,inwhichwedidallthesortsofthingswhichpeopleusuallydotoyoungpuppiesandnotedtheirreactionsonachecklist.Thistestwasgiveneverytwoweeksfrom5through15weeks,andonceagainatayear.

Asinglepairofexperimentersworkedwiththepuppiesupto16weeksofage.Thesewerealwaysamanandagirl,sothatthepuppieswouldhaveexperiencewithbothsexesandanopportunitytoshowdifferentialreactionstothem.Asecondpairofexperimenterswasaddedafter16weeks,butmanytestswerestillgivenbythefirstpair,sothateachlitterhadcontactwiththesameindividualsthroughouttheirtests.

Whenthepuppiesreached5weeks,webegantestingforthedevelopmentofsocialrelationshipsbetweenthepuppiesthemselves.Herewechoseonlyoneaspectofsuchrelationships,thatofdominanceandsubordination.Webeganpreparingforitat2weeksofagebyplacingabonebeforeallthepuppiesinthepen.Thiswasdoneonceaweekthereafter.At5weeksofage,thepuppieswerepairedineverypossiblecombinationwithinthelitterandallowedtocompetefortheboneoveraperiodof10minutes.Thiswasrepeatedat11and15weeks,andagainatoneyear.Apuppywasnotallowedtocompetemorethantwiceonthesameday.Thismeantthatthetesttookthegreaterpartofaweek,involvingagreatdealofhandlingandcontactwiththehumanexperimentersintheprocess.Italsomeantthatthelargerlittersobtainedmorecontactthanthoseinasmalllitter.Tims,ineachdominancetest,apuppy

inalitterof6wouldbehandled5times,whereasoneinalitterof4wouldbehandledonly3times.

THEPSYCHOLOGICALLEVEL:MEASURINGBEHAVIOR

Onthephysiologicalandsociallevels,ourchiefconcernwastokeepconditionsconstantsothatanydifferencesmightbecausedprincipallybygenetics.Whenwecametopsychologicalprocessessuchastheeffectoflearningandexperienceuponbehavior,wecarriedoutthesameprincipleforthefirstfewweeksoflife,interferingwiththepuppiesaslittleaspossibleandconfiningourdatatotheresultsofdailyandweeklyobservations.

However,insuchastandardizedandsimplifiedenvironment,therewasverylittleopportunityforlearningofanysort,exceptlearningtodonothing.Thisposedaproblem,asmanyofthemajordifferencesbetweenthedogbreedsshowupascapacitiestolearnvariousspecializedtasks.Wethereforedeliberatelybegantosubjectthedogstocertainkindsofproblemsandtraining.Indoingthiswesetupasecondareseriesofexperiments.Thesedidnotinterferewiththemajorgeneticexperimentbecauseeverydogwastreatedalike.Inthesecondaryexperiments,eachdogwasitsowncontrol,andtheresultsconsistedofchangesinbehaviorinreactiontothenewexperience.Differencesbetweenindividualscould,ofcourse,beinterpretedastheresultofheredity.

Thesocialtestsweredeliberatelyspacedatlongintervalssothattheeffectsoflearningresultingfromthetestitselfwouldbeminimized.Incontrast,eachpsychologicaltestwasdoneinashortandcondensedperiodoftimeinordertogetthemaximumeffectoflearningandexperience.Whiletheeffectsoflearningarelonglasting,theirgreatesteffectisimmediate.

Atfirstwethoughtofthesetestsasintelligencetests,butastimewentonandwehadmoreexperience,webegantocallthemperformancetests,sincetheanimalsseemedtosolvetheirproblemsinmanywaysotherthanthroughpurethoughtorintellect.

Firstbarrierordetourtest.—Wegavethefirstperformancetestat6weeksofage.Itillustratesmanyofthegeneralprincipleswhichwefoundusefulindesigningagoodanimaltest.Inthefirstplace,thetesthadtofitthecapacitiesofthespecies.Therewasnosenseinrequiringdogstodothingswhichdemandedtheuseofhands.Sincedogsareprimarilyhuntinganimals,wedesignedthetestaroundaproblemoffindinganobjectcontainingfood.Secondly,

20BEHAVIORPATTERNS

youngpuppiescouldnotberequiredtogobeyondtheirstrengthandgeneral

youngpuppiescouldnotberequiredtogobeyondtheirstrengthandgeneraldevelopment.Until3weeksofagetheyaresoimmaturethatlittlecanbedonewiththem,and,indeed,theyappeartobehighlyprotectedfrompsychologicalexperience.Wethereforedecidedtodothefirstperformancetestat6weeksofage.Beforethistimetheyoungpuppieshadalwayslivedinsidetheirpensandhadalmostnoexperiencewithbarriersofanykindexceptthewalls,whichtheycouldneithersurmountnorgoaround.Wethereforeattemptedtodiscoverwhetherornottherewasanygeneticallyproducedabilitytodealwithbarrierswithoutexperience.Wetookthepuppiesoutoftheirpensandplacedtheminastrangeroom.Forthefirsttwodaysagirlexperimentersimplytookapuppyintotheroom,putitonthefloor,andletitfindadishoffoodplacedbetweenherfeet.Thepuppywasgiventwominutestoeatandexplorethearea.Thiswasdoneonceonthefirstdayandthreetimesonthesecond,bywhichtimethepuppiesusuallywentrapidlytothefoodandateit.Onthethirdday,therewasabarrierintheroom.Experimenterandfoodwereononeside,thepuppywasplacedontheother,anditstaskwastofinditswayaroundtheobstacle.Sincethepuppycouldseethefoodthroughthebarrier,thedifficultylayinthefactthatithadtogoawayfromthefoodinordertoreachit.Onceithadsucceeded,thetestwasrepeatedtwicemore,inordertoreinforcememoryoftheevent.Onthenextdayamoredifficultbarrierwasintroduced,andonthethirddaythemostdifficultofall(Fig.10.1).

Thefirsttwodayswerethusdevotedtolearningthelocationofthegoalandtointensifyingmotivationbyrepeatedreinforcement.Withsuchyounganimalstheperformancecouldnotberepeatedmorethantwoorthreetimesinclosesuccessionwithoutthepuppylosinginterestorbecomingfatigued.Indeed,formanyofthemthreetimesappearedtobetoomany.

Motivation.—Intheseearlyexperimentsacombinationofrewards—food,theproximityoftheexperimenter,andbeingreturnedtothelittermates—wereallusedaspartofthemotivation.Becausetheexperimentermightaccidentallygivecuestothepuppies,shewasinstructedtositquietlyanddonothingbuttakenotes.Inexperi-mentswitholderanimals,theexperimenterwasifpossiblekeptcompletelyoutsidetheroomsothatthepuppyhadtoactindependently.

Thefoodrewardwasthusmadethebasicsourceofmotivation,sinceitcouldbestandardizedagooddealbetterthananyreward

ofapprovalorsocialcontact.Weusedateaspoonofcannedfishfortherewardandfounditworkedverysuccessfully.Therewasnoneedtostarvethepuppies

andfounditworkedverysuccessfully.Therewasnoneedtostarvethepuppiesbecausetheyeagerlyatethisadditiontotheirregulardietanddidnotbecomesatiatedonthesmallamountsfedthem.Makingthepuppieshungrywouldhavebeenundesirableinanycasebecauseofpossiblebadeffectsongrowth.Thesamecannedfishwasusedinallsubsequentexperimentsinvolvingafoodreward.

Relationshipbetweenperformancetests.—Asageneralprinciple,eachperformancetestwasdesignedtoprovidepretrainingforthosetocome.At8weekstherewasagoal-orientationtestinwhichthepuppieslearnedtoruntoaparticularspotintheroomforfood,andlatertoadifferentplace.Thistestinturnwasfoundationtrainingforamanipulationtestinwhichfoodwasplacedinthesamelocationbuthadtobeobtainedeitherbypullingthefooddishoutfromunderacoverorbypullingoffthecover.

At13weeksofagethepuppiesgotasecondbarriertest,thistimeinamorecomplexform.Thustheperiodupto16weekswaslargelydevotedtoobservationofdevelopmentandtestsofsocialbehavior,withafewelementarypsychologicalteststhrownin.Theperiodfrom16weeksto35weeks,ontheotherhand,wasdevotedlargelytoperformancetests,sincetheanimalswerenowphysiologicallycapableofalargenumberofco-ordinatedmovements.Thepuppieswerealsolargeenoughbythistimesothattheirphysiologicalreactionscouldbeeasilymeasured.

At16weekseachlitterwasplacedinalargeoutdoorrunwhereitremainedasaunituntilthepuppiesreachedtheageofoneyear.Theywereatfirstsomewhatdisturbedintheirnewsurroundings,andwefoundthattheymadethetransitionmuchmorepeacefullyifweputthemoutforafewhoursononeday,broughtthembackintotheirformerpenovernight,andthenextdaypermanentlymovedthemoutside.

Thereaftertestsweredoneinoneofthreeplaces.Onewasthehomepenitself,inwhichthepuppiessoonbecamehighlyconfidentandrelaxed.TheothertwoareaswereinsidetheBehaviorLaboratoryinplacesunfamiliartothepuppies,sothatwehadtheproblemofpreparingthemforworkinginanunfamiliarenvironment.

Emotionalreactivitytests.—Wefirstdevisedatestofemotionalreactionstoatotallynewsituation(Fuller,1948).Thepuppieswerecarriedintoacontrolled-environmentlaboratoryandsubjectedtoavarietyofmildlyfrighteningsituations(loudnoises,

situations(loudnoises,

22BEHAVIORPATTERNS

isolation,weakelectricshock,etc.)whiletheirexternalandinternalemotionalreactionswerebeingrecorded.Thistestwasdoneat17,30,and51weeksofage.

Trainingtests.—Thefirstofthisgroupwasleashtraining(Fuller,1955).Thepuppywastaughttofollowanexperimenterintothebuilding,givenafoodreward,andafterwardstakenonaleashoverthesameroute.Thereafterhewasledalloverthebuildingwithoutfurtherrewards,inordertofamiliarizehimwiththenewtestsituations.Themethodwasessentiallythatofforcedtraining,combinedintheearlyphaseswithfoodrewards.Anotherexperienceofforcedtrainingwasgivenintheobediencetest,scheduledat30weeksofage,inwhichpuppieswereplacedonaboxandtaughtto"stay"untilacommandwasgiven.

Testsforspecialabilities.—Stillanothergroupoftestsattemptedtomeasurecertainspecialabilitiespeculiartotheindividualbreeds.Thefirstofthesewasanartificialtrackingtest.FishjuicewassmearedonmetalplatesattachedtothinstripsofboardwhichcouldthenbelaidoutinvariouspatternsleadingtoaSyracusedishholdingasmallbitoffish.Similaruntreatedplateswerelaidoutasfalsetrails.Wewishedtoseewhetherbeagles,whicharegenerallyusedfortrackingbyscent,wouldgiveasuperiorperformanceinthissituation.

Asecondtestofthiskindattemptedtomeasurethespecialclimbingabilityofbasenjis,whichwehadalreadyobservedintheirsuccessfulattemptstoclimbupontheirhousesandtoescapefromtheirruns.Inthistestthedogshadtoclimbsteeperandsteeperrampstoreachthetopofapileofboxesonwhichfoodwasplaced.Thefinaltestrequiredtheanimalstowalkacrossanarrowplankstretchedbetweendieboxesandthetopofthedoghouseintheirhomepen.Asitturnedout,theoutcomeofthetestwasstronglyaffectedbymotivationalfactorsaswellasmotorskill.

Athirdtestofthissortwastheretrievingtest,inwhichweattemptedtomeasurethewell-knownabilityofcockerspanielstolearntoretrieveobjectsmorerapidlythansomeotherbreeds.Ouroriginalattemptstomeasureretrievingweredonewithyoungcockerpupsbetween8and10weeksofage,andtheseanimalsdidverywellwhentestedagainat32weeks.However,whenwesubsequentlyabandonedtheearlytraining,performanceatthelateragewasverypoorforallbreeds,andthetestthereforegaveinconclusiveresults.Thereisanindication

breeds,andthetestthereforegaveinconclusiveresults.Thereisanindicationhereofacriticalperiodforlearningthisparticularsortofskill.

Problem-soilingtests.—Finally,therewasagroupoftestswhich

SCHOOLFORDOGS23

attemptedtomeasuremoreabstractkindsofintelligence.FromWeeks22to26,allthepuppiesweregivenaseriesoftestsinasimpleT-maze.Afterlearningtorunthroughthemazetoreceivefood,thedogsweretrainedtoruntowardthearmoftheTinwhichapanelwasmovedrhythmically.Amovingobjectwaschosenasthecuebecausethedogsappearedtonoticemovingobjectsmorereadilythanstationaryones.Someanimalsshowedextremelyrapidlearninginreactiontothiscue,butotherswereafraidofitand,indeed,ofthewholeT-maze,andtheirlearningwasconsequentlyretarded.Inthis,asinallotherperformancetests,emotionalandmotivationalfactorswerealwaysimportant.Thistrainingwasusedasthebasisforadelayedresponse,orvisualmemorytest.

Anothertestofintellectualcapacitywasdevelopedfromthemotor-skilltestandwascalledspatialorientation.Theanimalshadtoclimbrampsandcrossbridgessimilartothoseusedintheearliertest.Theapparatusremainedinthepenscontinuouslythroughoutthetest,sothatthesubjectscouldbecomecompletelyfamiliarwithit,anditoftenbecameafavoriteplaceforthedogstostandorsit.Duringthetesttheapparatuswasarrangedwithacentralfoodboxtowhichtherewasonlyoneopenpathway.Ahumanbeingcouldhavevisuallyinspectedthebarriersandimmediatelygonetothecorrectramp.Wehopedbythistesttomeasureobjectivelytheextenttowhichthevariousbreedsareorientedbyvisionandcapableofsolvingproblemsthroughtheuseofthissense.Ourhopeswerenotcompletelyrealized.Strikingindividualandbreeddifferenceswereobtained,buttheresultsdidnotsupportthehypothesisofasimpledifferenceinsensorydominance.Manyoftheanimalsappearedtosolvetheproblembyroutinelytryingeachpossiblesolutioninturnwithoutvisualinspection.

Aftertheterminationofthespatial-orientationtest,atabout8monthsofage,thedogsweregivenavacationuntiltheywereapproximatelyayearold.Duringthistimetheywereobservedregularlybutgivennoformaltests.Beginningat51weeks,alltheanimalsweregivenafinalbatteryoftests,mostofwhichrepeatedearlierones,withtheideaoffindingouthowstablethepreviouslyobserveddifferenceshadbecome.Thereactivityandhandlingtestswererepeated,social-dominancerankswereagainmeasuredwithineachlitter,physicalmeasurementsweretakenforathirdtime,andanewtestoffrustrationtolerancewasgiven,in

weretakenforathirdtime,andanewtestoffrustrationtolerancewasgiven,inwhichdogswereconfinedtosmallcagesandsubjectedtovarioussortsofstimulation.

BEHAVIORPATTERNS

historyofeachanimalintheexperimentissummarizedinTable1.3.Asthereweresome30majortestingsituations,eachofwhichincludedmultiplemeasurementsresultinginfrom5to40scores,thedataoneachanimalranintothehundreds.Testinghundredsofanimals,weeventuallyaccumulatedthousandsofmeasurements.

TABLE1.3

ScheduleofObservations,Training,andTesting

Test

Dailyobservation

Weeklyobservation,weighing

Maternalbehavior

Responsetohandling

Dominance

Group

Paired

Firstbarrier(detour)

Responsetoveterinarycare..Goalorientationorhabit

formation

Manipulation

Secondbarrier(maze)

(Transferredtooutsideruns).Bi-weeklyinspection,

catchingtime

Somatotype,weighing

Reactivity

Following

Leashcontrolandstair

climbing

Motivation,T-maze

Discrimination,T-maze

Delayedresponse,T-maze...

Trailing

Motorskill

Obedience

Retrieving

Spatialorientation

Physiologicalassessment

Responsetoconfinement

Social

Emotional

ForcedTraining

RewardTraining

ProblemSolving

PhysicalorPhysiological

Age(weeks)

0-160-16

1.7

5,7,9,11,13,15,52

2,3,4,6,7,8,9,10

5,11,15,52

6

8,10,12,14

9

10

14-1517

11:2

17,34,5117,34,5118

19-20

22

23

24-26

27

29

30

32

33-36

51

51

Inthefollowingchapterswehaveselectedforexhaustivetreatmentonlythosemeasureswhichseemedmostmeaningfulinviewofourgeneralobjective:todiscovertheinfluenceofhereditarydifferencesuponbehavior.Moredetaileddescriptionsofsomeofthetestsandmeasuresaregivenlaterintheappropriatechapters.

Byandlarge,thissystemoftestingwasverysatisfactory.Thepuppieseasilytransferredtheirbasicmotivationaltrainingfromonetesttoanother,andtherewasnoindicationthattheyweresolvingtheirproblemsbywatchingtheexperimenterinsteadofusingtheirbrains.Ontheotherhand,thepuppieswerecontinuallybeingexposedtonewsituationsandnewproblems,andtheyneverhadachancetogobackandpracticefamiliartasks.Iftheprogramhadbeensetupsothatthepuppiescouldhavegonebackandrepeatedsomeofthethingswhichtheyhadalreadylearned,theymighthave

SCHOOLFORDOGS

25

shownmoreconfidencewhentheycameupagainstnewproblems.Oursubjectiveimpressionwasthatourpuppieswerenothighlyconfidentinpsychologicaltests,contrastingwiththeirbehaviorinsocialrelationshipswitheachotherandwiththeexperimenters,inwhichlongfamiliaritymadethemhighlyconfident.

THEECOLOGICALLEVEL:SPACEANDCOMPLEXITY

Ourchiefconcernherewastokeepthephysicalenvironmentasuniformaspossibleforallanimalsandatthesametimemaintainsurroundingsreasonablynormalfordogs.Oneofourchieflimitationswasspace.Wecouldnotgiveeachdogthesquaremileorsoofterritorywhichhemighthavehadifraisedona

dogthesquaremileorsoofterritorywhichhemighthavehadifraisedonafarm.Duringpuppyhoodwekepteachlitterinalargeroommeasuring10by18feet,whichisnotfarfromthesizeofthespaceinwhichveryyoungpuppiesconfinetheirwanderings.At16weeksofagetheywereputintolargeoutsideruns,20feetwideby75feetlong.Inthese,a

i

m

NestBox

SideCover

Bench

IE"——

Motorr*'—'—'—

Rodi

Romp

•Door

Step

FoodPlatform

NURSERYROOM18*x13'

Fence

Waterw

Alley8Gutter

ObservationWindow

Door

FLOORPLAN

Fig.1.2.—Floorplanofnurseryroom.Theentirelivingspaceforthemotherandpuppiesis10X18feetandsoarrangedthatallpupsarevisiblefromtheobservationwindows.Onesideofthenestboxcanberemovedandlaiddownonthefloorsothatitsinteriorisalsovisible.

26BEHAVIORPATTERNS

litterofsixdogscouldliveinclosecontactbutnotseriouslyinterferewitheachother'sfreedomofmovement.Subsequentexperiencewithsmallerpens,20by40feet,indicatesthatinsuchpensinterferencedoestakeplacewithingroupsofthissize.

Astoobjectswithinthepensweprovidedonlyaminimumnumber,sothatitwouldbeeasiertokeepconditionsuniform.Inthenurserypenstherewasthenestbox,thewaterpail,fooddishes,andasmallbenchwhichwasfrequentlyusedbythepuppiesasahidingplace.Apieceofautomobiletirecasingwasleftinthepensforthepuppiestochewon,andasimilarpiecehungfromtheceilingwheretheycouldleapupandgrabit.Assoonasthepuppieswereoldenough,theirfoodwasplacedonaplatformwhichcouldbemountedeitherbystepsoralongarampconsistingofacleatedboardabout6incheswide.Thisgavethepuppiesexperiencewithverticalaswellashorizontalspace.

Intheoutsidepenstherewereveryfewobjectsexceptthenestboxes,waterdishes,andafewstonesmixedinwiththegravelfloorofthepen.Thenestboxesthemselveswereconstructedwithinsulatedwallsandroofforprotectionagainsttheweatherandwerereachedbyanindirectpassage(seeFig.1.3)sothatthedogslivedinwhatwasessentiallyanartificialdenkeptwarmbytheirbodiesandprovidedwithampleventilationwithoutdrafts.

Thereweremanyphysicalfactorswhichcouldnotbecompletelycontrolled.Thesewereenteredintherecordssothattheirpossibleeffectscouldbelateranalyzed.Onesuchvariablewastheseasoninwhichthepuppieswereborn,thisdeterminingtheseasoninwhichtheywerelatertestedandthusproducinganartificialcorrelationbetweentestresultsandtemperatureandotherweatherconditions.Wealwaysnotedthetemperatureatwhichanytestwasgivenandmaintainedapermanentrecordoftheoutsidetemperatureonarecordingthermometer.Whentestsweregivenoutdoors,werecordedtheweatherconditions,suchasrain,snow,etc.Testswerenevergivenduringactualstorms.

Theenvironmentintheoutsiderunswas,ofcourse,muchmorevariablethanthatinthenurseryrooms.Thiscircumstancewasnotentirelybad,becauseitmadetheolderdogssomewhatinsensitivetorandomenvironmentalstimulationfromnoisesoutsidetheirpens,whereasananimalkeptcontinuouslyinamorelimitedenvironmentwouldbelikelytoover-reactattheslightestnewstimulation.

Hebb(1947)liasshownintheMcGillUniversityPsychologicalLaboratoriesthatratsraisedaspetsinahomearesuperiorintheir

SCHOOLFORDOGS

27

performanceinpsychologicalteststoratswhichareraisedinordinarylaboratorycages.Heinterpretsthisastheresultofenrichingtheirenvironment.Judgedbythisstandard,thephysicalenvironmentofourdogswasrelativelybarren.Weattemptedtoenrichitintwoways:bybringingobjectsintotherearingpensduringtheexperiments,andbytakingthedogsoutandintroduc-

3"6'

FoodIHopperQ

-ifiT—.

Sun

porch

FLOORPLAN

FLOORPLAN

HOUSE3'6"x3'6"

Cleanoutdoor

(I'6"x2')

mmmt^§

I2H

Insulatedwall

3'6"IV

Insulatedroof(removable)

SIDEVIEW

Skid

INSULATEDDOGHOUSE

Fig.1.3.—Floorplanofall-weatherdogkennel.Theindirectentranceisdraft-freebutprovidesventilation.Insulatedwallsandroofkeeptemperaturesatcomfortablelevelsinbothcoldandwarmweather.

ingthemtootherenvironments.Ouranimalscertainlydidnothaveasrichanexperienceasadogrunningfreeonafarm,althoughtheirenvironmentmightcomparequitefavorablywithadogrearedinacityapartmentandnevertakenoutexceptonaleash.Underourconditionsthedogsprobablyneverdevelopedalloftheircapacitiestoamaximumdegree.Oneofourmajorconcernswastoprotectthemfromenvironmentalaccidentswhichmight

eithercrippleorgiveanundueadvantagetooneindividual.Fromanecologicalviewpoint,wehadtodevelopasortofmicro-climateandmicro-environmentwhichpartiallyexcludedtheoutsideworld.Forexample,ourdogsintheoutsiderunsweresurroundedbyfences4feethighwhichpreventedtheirobservingthingsatadistanceandalsopreventedceaselessrunningandbarkingatdogsintheneighboringpens.Theycouldtellwhendogsorpeoplecameclose,butthesecontactshadlittleseriouseffectontheirlives.Theimportanteventstookplacewithintheirpensorinthetestingrooms.

SUMMARY

Whenwestoodbackandlookedatthecompleteddesignofourexperiment,wediscoveredthatwehadevolvedavirtual"schoolfordogs."Ittookusnearly5yearstogeteverythingrunningsmoothlv,andtheschoolwastooperateatitspeakefficiencyforalmost8yearsthereafter,whilewetestedsomefivehundredpurebredandhybridpuppies.

Inthesameamountoftime,anelementaryschoolteacherwithaclassofthirtypupilsayearcouldhavemetandinfluencedthesamenumberofindividuals.We,asteachersinthisuniqueestablishment,learnedagreatdealwhichhasapplicationtothescienceofeducation,aswillappearinlaterpages.However,wewereprimarilyexaminersratherthanteachers,andourchiefconcernwastomakesurethatourpupilsgaveusanswerstothebasicscientificquestionswhichwehadaskedthem.

Oneofthefirstquestionswas,Whatkindofananimalisadog?Inevaluatingtheanswerswewouldfindthatadogisnotafour-leggedandchildishhumanbeingdressedupinafurcoat.Ourdogscouldthereforegiveusanswerstootherquestionsonlyasdogs,closelyrelatedtohumanbeingsthroughsocialcontactsbutbasicallycarnivoresintheirheredity.

DOGS,WOLVES,ANDMEN

Dogsareextraordinarilyvariableanimalsinallvisiblerespects.Therangeinsizeisalmostincredible;aChihuahuamayweigh4poundsandafull-grownSaintBernard160,orfortytimesasmuch.Legsvaryfromthesquatextremitiesofdachshundstothelong,gracefullimbsofgreyhoundsandsalukis.Atoppositeextremesweseetheundershotjawsandforeshortenedheadsofbulldogsandpugs,andthelong,narrowheadsoftheborzois.Tailsvaryfromatightcurltoasickleshape.Manifoldvariationsinthecolor,length,andtextureofhairexist

sickleshape.Manifoldvariationsinthecolor,length,andtextureofhairexistandthereisevenapermanentlybaldbreed,theMexicanhairless,contrastingwiththepoodlewithitscontinuouslygrowinghair.

Linnaeus,thegreatSwedishnaturalistwhooriginatedoursystemofclassificationofanimalsandplants,placedthedoginonespeciesandcalleditCanisfamiliaris,thefamiliardogascontrastedwithCanislupus,thewolfdog.Laternaturalistswonderedwhethersuchahighlyvariablespeciescouldreallyhavehadonecommonorigin(Darwin,1859;Packard,1885;Hilzheimer,1908).

Thisraisedthequestions,Whatisadog?andWherediditcomefrom?aswellastherelatedproblemsofwhenandhowthisoccurred.Sincethesearequestionsofprehistory,therecanneverbeanycompleteandfinalanswerstothem,andthebestwecandoistoassembletheavailableevidenceanddrawthemostprobableconclusions.Asweshallsee,mostoftheevidencesupportstheideathatdogshaveaunifiedcommonancestry,beingdomesticatedfromwolvessomeeighttotenthousandyearsago.

29

30BEHAVIORPATTERNS

EVIDENCEFROMTAXONOMY

ANDGEOGRAPHICALDISTRIBUTION

Taxonomyisthescienceofclassification.BeginningwithLinnaeus,biologistsbegantoclassifyanimalsaccordingtogenusandspeciesonthebasisoffundamentalsimilarities.Theideaofwhatconstitutesaspecieshasgraduallydevelopeduntiltodaywedefineaspeciesasapopulationofanimalswhichbreedtogetheror,togiveageneticdefinition,apopulationhavingaccesstoacommonstoreofgenes.Thismeansthatgroupsoflandanimals(likemostmammals)mustshowgeographicalcontinuityintheirdistributioninordertobeconsideredspecies.Suchpopulationscansometimesbedividedintolocalraces,butthesearestillpartofthesamespeciesifthereiscontinuousinterbreedingbetweenthem.Alocalraceiscalledasubspeciesifitshowsdistinctdifferencesfromothersuchpopulations.

Thedefinitionofaspeciesasapopulationhasproducedagradualbutdramaticrevolutioninthescienceofclassification.Theearlytaxonomistsworkedbyfirstminutelydescribingaparticularindividualspecimen,or"tyPe>"andthenincludinginaspeciesallindividualswhichcloselyresembledit.Sincethereisa

includinginaspeciesallindividualswhichcloselyresembledit.Sincethereisagreatdealofvariationwithinapopulation,itwaseasyfortwodifferentnaturaliststopickupdifferentspecimensfromthesamepopulationanddescribethemasseparatespecies.Consequently,theolderscientificliteratureonthesubjectisveryconfusing,andeventodaytheclassificationschemehasnotbeencompletelyrevised.Thefollowingdescriptionisbasedonthelatestavailableclassificationofdogsandtheirrelatives.

Tobeginwiththelargertaxonomicdivisions,dogsbelongtotheorderCarnivora,whichisdividedintotwolargegroups,thewater-livingformslikethesealsandotters,andtheland-livingones,whichincludesevendifferentfamilies:thebears,raccoons,weasels,civets,hyenas,cats,anddogs.

Membersofthedogfamilytypicallyrunontheirtoes,incontrasttothebearsandraccoonswhichwalkontheirheels.Theyarebestadaptedforswiftrunninginopencountry,andthelargeronesusuallycapturetheirpreybyrunningitdown.ThefamilyCanidaeincludestheFoxesandtheso-called"wilddogs"—theAfricanhuntingdog,theSouthAmericanbushdog,andthedholeofIndia—aswellasthetruedogsandwolves.

Thetaxonomistsoriginallyplacedseveralcommonanimalsinthe

genusCanis:C.familiaris,thedomesticdog;C.dingo,theAustralianwilddog,ordingo;C.lupus,thegraywolf;C.latrans,thecoyote;andC.aureus,thejackal.AllofthesearestillincludedinthegenusCanis,exceptthejackal,whichsomeexpertsplaceinaseparategenus,Thos.Eachofthesespeciesoccupiesasomewhatdifferentecologicalniche.WolvesarehuntersofthelargeungulatesintheNorthernHemisphere,pursuingcaribouinarcticregionsanddeerormooseinmoresouthernclimates.Theyliveontundras,inforests,oronplains,wherevertheirpreyisfound(AllenandMech,1963;YoungandGoldman,1944).Theircloserelatives,thecoyotes,aresmalleranimalsoftheplainsanddeserts,chieflyhuntingrabbitsandsmallrodentswhichtheyfindthere,aswellasbeingscavengersandcarrioneaters(YoungandJackson,1951).IntheOldWorld,jackalsarethecounterpartsofcoyotes,beingscavengersofthesouthernandequatorialdeserts.Domesticdogs,ofcourse,arefoundallovertheworldincloseassociationwithman,livinginavarietyofclimatesandeatingavarietyoffood.ThedingoisahunterofmarsupialsentheAustralianplainsanddeserts,andmorerecentlyhastakentopreyingondomesticsheep.

ThefossilevidenceshowsthatthefamilyCanidaeoriginallycamefromthe

ThefossilevidenceshowsthatthefamilyCanidaeoriginallycamefromtheNorthernHemisphere,andthedistributionofitsdescendantsisconsistentwiththis.WolvesarefoundonlyinNorthAmericaandEurasia.YoungandGoldman(1944)recognizedtwospeciesofwolvesinNorthAmerica,C.lupus,thegraywolf,andC.niger,theredwolfformerlyfoundintheMississippiValleyandsoutherncoastalpartsoftheUnitedStates.Eachcanbedividedintovarioussubspecies.Thegraywolf,C.lupus,isalsofoundinnorthernEuropeandAsia,withasubspecies,pallipes,inIndia.Thisisasomewhatsmalleranimal,andsomescientistsconsideritaseparatespecies.TherearenonativewolvesinAfrica,SouthAmerica,Australia,orAntarctica.

Thecoyote,C.latrans,isfoundonlyinNorthAmerica,andoriginallyrangedfromAlaskanearlytoPanama(YoungandJackson,1951).Thejackalshavesometimesbeendividedintomanyspecies,butatpresentthereareonlythreedefinitelyrecognizedspecies(Hildebrand,1954).TwooftheseliveonlyinAfrica.Thecommonyellowjackal,C.aureus,rangesfromnorthernAfricathroughAsiaMinortosoutheasternEurope,andinaneasterlydirectiontoIndiaandbeyond.Thejackalsarethusamoresoutherngroupthananyothermembersofthegenus.

Thedomesticdoghasthewidestdistributionofany,beingnowfoundonallinhabitedcontinentsandalwaysincloseassociation

BEHAVIORPATTERNS

withman.Beforemoderntimes,dogswerefoundonallcontinentsexceptAustraliaandAntarctica.TherewereseveralkindsofnativedogsinAfricaandSouthAmerica.EveninAustraliatherewasthedingo,whichissosimilartothedomesticdogthatitissupposedtohavebeenintroducedbytheaboriginesandlatergonewild.Thisismademoreprobablebythefactthatthedingoisoneofthefew

W=Southernboundaryofdistributionofwolf(Cornslupus)J»Northernboundaryofdistributionofjockal(Conisaureus)C=Distributionofcoyote(Conistotrons)*-#Proboblecenteroforiginofdog

AmericanMapCo.,NewYork.

Fig.2.1.—GeographicaldistributionofwildmembersofthegenusCards.WolvesarenorthernanimalsofEurasiaandNorthAmerica,whereasjackalsbelonginAfricaandsouthernAsiaandcoyotesareconfinedtoNorthAmerica.Theearliestknownremainsofdogs(inDenmark)fallwithintherangeofthewolf.(ModifiedfromWerth,1944)

placentalmammalsoriginallyfoundinAustralia.Theothersincludeman,severalkindsofratsandmice,andavarietyofbats.

AssumingthatthedogmusthavebeendomesticatedfromsomeexistingspeciesbelongingtothegenusCanis,andthatthisspeciesmusthavebeendomesticatedataplacewithinitsnaturalrange,thegeographicalevidenceeliminatesSouthAmericaasapossibledomesticationcenter,sincenowildspeciesofthegenusCanishaseverlivedthere.WecanalsoeliminateAustralia,asthedingoisFarmorelikelytobeadomesticdoggonewildthanitistobeanancestralform(Werth,1944).WecannoteliminateAfrica,butif

DOGS,WOLVES,ANDMEN33

dogswerefirstdevelopedonthatcontinent,theycanonlyhavebeendomesticatedfromjackals,sincejackalspeciesaretheonlyonesfoundinthatarea.InEurasia,dogscouldhavebeendomesticatedfromeitherwolvesorjackals,whereasinNorthAmericatheonlypossiblecandidatesarewolvesand

jackals,whereasinNorthAmericatheonlypossiblecandidatesarewolvesandcoyotes.

Theevidencefromgeographicaldistributionoflivinganimalsthusnarrowsdownthepossibleancestorsofthedog.Thereremainsthepossibilitythatthedogcouldhavebeendomesticatedfromawildspeciesnowextinctorfromsomeoftheso-called"wilddogs"nowliving.

EVIDENCEFROMFOSSILS

The"wilddogs"caneasilybeeliminated.ThesedistantrelativesofthedogincludeLycaon,theAfricanhuntingdog;Icticyon,theSouthAmericanbushdog;andCuon,thedholeofIndia(the"reddog"ofKiplingstories).AccordingtoMatthew(1930),thefoxesandwolveshaveacommonancestorintheMiocene,somesevenandahalfmillionyearsago,buttheirrelationshipwiththewilddogsismuchmoreremote,tracingbacktoacommonancestorintheOligocene,sometwentymillionyearsago.Thisprettywellexcludesthe"wilddogs"asancestorsofthedomesticones.TheyareactuallymoredistantlyrelatedtothegenusCanisthanarefoxesandarequiterightlyplacedindifferentgenerafromthedog.

Atvarioustimesscientistshavespeculatedthatthemoderndogisdescendedfromasmallwilddogwhichisnowextinct(Allen,1920).Todate,nosuchhypotheticalancestorhasbeendiscovered.Matthewfindsthatwolves,coyotes,jackals,andfoxeswerepresentinessentiallytheirmodernformsinPleistocenetimes,overhalfamillionyearsagoaccordingtorecentestimates(Kulp,1961).Thesefourkindsofanimalshaveremaineddistinctfromeachothereversince,andtherearenoskeletalremainsuntilrecenttimeswhichcanbeidentifiedasdomesticdogs.Thesedogremainsarenotfossilsbuttruebones,discoveredbyarcheologistsinassociationwithhumanskeletons,ruins,andartifacts.

EVIDENCEFROMPREHISTORY

Beingadomesticanimal,thedogisalwaysfoundincloseassociationwithman,andthebestevidencefortheexistenceofprehistoricdogscomesfrombonesfoundwithprehistorichumanremains.Thescienceofarcheologyisnowinastateofferment,partly

34BEHAVIORPATTERNS

becauseofnewtechniquessuchasradiocarbondating,whichmakesitpossible

becauseofnewtechniquessuchasradiocarbondating,whichmakesitpossibletoestimatetheageofbonesandotherorganicremainsonanobjectivescale,andpartlybecauseofanewinterestinthedomesticationofanimalsandplants.

BraidwoodandReed(1957)describetheprehistoric"agriculturalrevolution"whichproducedasprofoundchangesinthelivesofearlymenasdidtheindustrialrevolutionintheexistenceofmodernman.Earlymenlivedbygatheringwildplantsandotherfood,andoccasionallyhuntinginpacks.Withthedomesticationofplantsandanimals,theyhadaccesstoagreatlyincreasedfoodsupply,couldliveinmuchgreaternumbers,andbegantosettleinvillagesandtowns.Thedogisdifferentfrommostdomesticanimalsinthatitwouldhavebeenusefulbothtohuntersandtoprehistoricfarmersandherdsmen.

Theagriculturalrevolutiontookplaceinmanypartsoftheworld,butitfirstbeganinthe"fertilecrescent,"thefoothillsofthemountainssurroundingMesopotamiaandPalestine,andthisistheareawhichBraidwoodandReedhavestudiedmostintensively.Reed(1959,1960)statesthattheearliestauthenticremainsofadoghavebeenfoundinJerichoanddatesthematapproximately6500B.C.oreighty-fivehundredyearsago.InthecontemporaryagriculturalvillageofJarmothereareseveralclayfigurineswhichareidentifiableasdogsbecauseoftheircurlytails.Itispossiblethatevenearlierremainsofdogswillbefoundinthefuture,butthisisamatterofconjecture.Incontrast,thefirstevidenceofdogsinEgyptisdatedatonly3500B.C.,somethreethousandyearslater.Theevidenceisabowlwitharecognizablepictureofsomegreyhounds,orsalukis.Long-limbedskeletonsofthesamedatehavebeenfoundinMesopotamia,wheresalukiswereprobablyfirstdeveloped.ItlooksasiftheuseofthedogspreadslowlyfromPalestineintoEgypt.

ThedogsinIraqtodayincludethesaluki,atallgreyhound-likeanimalusedforhuntinggazelles,andalargeheavilybuiltguardandherddogusedbytheKurdishshepherds(Hatt,1959).Itisdifficultorimpossibletodiscriminatethebonesoftheselatterdogsfromthoseofthelocalwolves,andthisregionisdefinitelyapossiblecenterforthefirstdomesticationofthedog(Reed,1959,1960).

TheonlyotherareaoftheworldwhichhasbeenstudiedasintensivelyisWesternEurope.TheoldestauthenticdogremainscomefromDenmark,discoveredtherebyDegerb0l(1927).ThebonesandhumanartifactsfoundwiththembelongtoaculturalperiodknownastheMaglemosian,thelatterpartoftheMesolithicperiod


duringthetransitiontotheNeolithic.Theseremainshavenotbeencarbondated,butotherestimatesplacethemfrom8,000to10,000b.c.Reed(1959)thinksthattheymaybeeitherolderorsomewhatmorerecentthanthebonesfoundinJericho.Astheevidencenowstands,theearliestremainsofdomesticdogscomefromDenmark,withthosefromtheMiddleEastfallinginsecondplace;butthisconclusionmayhavetoberevisedinthelightoffuturediscoveries.

MorerecentStoneAgedogshavebeenfoundinEuropeassociatedwiththeSwisslakedwellers,andothershavebeendugupfromthebottomofLakeLadogainRussia.Usingthetypemethod,theolderarcheologistsdescribedeachoftheseremainsasseparatesubspeciesofdogs,givingthemsuchnamesas"Cantsfamiliarismatrisoptimae,"andStuder(1901)triedtotracemodernbreedsbacktothem.Dahr(1937)foundthattheseStoneAgedogs,farfrombeingspecializedbreeds,wereallverymuchalikeascomparedtothewidelyvaryingmodernbreeds,andmostauthorsnowagreethattheirremainsaresimilartotheskeletonsofmodernEskimodogs.Degerb0lstatedthathisearlierspecimensweredistinctlydifferentfromwolvesinhavingsmallerteethandjaws.Thiswouldargueagainstthedogbeingdomesticatedinthatarea,butagainwemustconcludethattheevidenceisstillquiteincomplete.

TheoriginaldoginhabitantsofNorthAmericawereextensivelystudiedbyAllen(1920),whofoundthatallofthemshowedresemblancestowolvesratherthantocoyotes.Haag(1948)laterestimatedthattheearliestdogremainsintheWesternHemispherecanbedatedabout1500b.c,butthisdatemaybetoorecent.Atanyrate,itismuchlaterthaneventheEgyptiandogs,anditislogicaltosupposethatdogswereintroducedintoNorthAmericabytradingorbymigratingpeoplescomingacrosstheBeringStraitintoAlaska.Otherareasoftheworld,includingSoutheastAsia,areallrelativelyunknownfromthearcheologicalpointofview.Perhapsnewdiscoverieswillchangethepicture,butatpresenttheonlystrongcontendersforthecenterofdomesticationofthedogareDenmarkandMesopotamia.

Therearetwopossibletheoriesregardingtheoriginofthedog.Oneisthatthedogwasdomesticatedonceandspreadrapidlyallovertheworldfromthiscenter.Analternatetheoryisthatthedogwasdomesticatedatseveraldifferenttimesandplaces.IfthefirsttheoryiscorrectandDenmarkwasthecenteroforigin,thedogcouldonlyhavebeendomesticatedfromthewolf,asthatistheonlywildmemberofthegenusCaniswhichexistedinthatregion.If

onlywildmemberofthegenusCaniswhichexistedinthatregion.IfMesopotamiawasthecenter,dogscouldhavebeendomesticated

BEHAVIORPATTERNS

AmericanMapCo.,NewYork.

Fig.2.2.—Centersofdomesticationandhypotheticaladaptiveradiationofdogsfromthesecenters.Solidlinesrepresentthenortherndogs,andbrokenlinesthesoutherndogs,includingthebasenjianddingo.

fromeitherthewolforthejackal.However,ifdogsweredomesticatedatvarioustimesandplaces,thefieldofpossibleancestorsisstillwideopen.

EVIDENCEFROMCOMPARATIVEANATOMYANDPHYSIOLOGY

OneofthedifficultiesofstudyingprehistoricdogsisthattheirbonesaresometimesindistinguishablefromthoseofwolvesorothermembersofthefamilyCanidae.Biologistsfrequentlyhavethesamedifficultyinidentifyingrecentlykilledspecimens.IsthelargedoglikeanimalwhichwasshotwhilekillingdeerasmalltimberwolforalargeGermanshepherd?Inmanycasestheexpertcanonlygiveanopinionratherthanadefiniteidentification.

Anyonewholooksatwolvesinzoologicalparksisimmediatelyimpressedwiththeirdoglikeappearance.Thereareonlyafewnoticeabledifferences.Theyhaveheaviercoatsthanmostdogsandlong,bushytailswhichareonlyslighdycurved.Thegeneralshapeoftheirheadsisdoglike,andtheirearsareerect.Theyarelargerthanmostdogsandmayweighanywherefrom60to175pounds(YoungandGoldman,1944).Theirlarge,heavyheadsandlong,heavilyboned

(YoungandGoldman,1944).Theirlarge,heavyheadsandlong,heavilybonedlegscontrastwiththoseofmostdogs.Inshort,they


arepowerful,ruggedanimals,nothighlyspecializedforanyoneactivity.Theylooklikebigdogs,butwithoutanyoftheheadortaildeformitieswhicharecharacteristicofsomedogbreeds.

Coyotes,ontheotherhand,aremuchsmalleranimals.Theaveragecoyoteweighsabout25pounds,withtherangeextendingbetween18and30,exceptforsomeexceptionallylargeanimalswhichmayweighasmuchas74pounds(YoungandJackson,1951).Theirgeneralbodyproportionsarethesameaswolves(Hildebrand,1954),buttheyhaveproportionatelylongernecksandnarrowermuzzles,givingthemthegeneralappearanceofalargefox.Theyarespecializedforfastrunningandforhuntingsmallanimalslikerabbitsandgroundsquirrelsontheopenplains.

ThethirdgroupofwildrelativesofthedogsarethejackalsoftheAfricanandAsiandeserts.Theyareverysimilartothecoyotesbothinappearanceandwayoflivingbutareevensmallerinsize,theaverageadultweighingonlyabout20pounds.

Wecanconcludethattheprincipalanatomicaldifferencebetweenthesethreewildspeciesisamatterofsizebutthatthisisnotanabsolutedifference,sincecoyotesoverlapbothwolvesandjackals.Dogs,ofcourse,overlapalltheseanimalsinsize,thedwarfbreedsbeingsmallerthanthesmallestjackals,andthelargestdogsbeingaslargeasthelargestwolf.Thereisthereforenodistinct"dogtype"whichcanbeimmediatelydistinguishedfromthewildspecies.Ofcourse,therearecertainindividualdogsandbreedswhicharedistinctlydifferent.NoonewouldconfuseaChihuahuawithajackal,andabulldogisimmediatelyrecognizableforwhatitis.Suchextrememutanttypesamongdogsareeasilyidentified,butthevastmajorityofthebreedsarereasonablynormalinbasicanatomy,andifwearetodiscoveranythingregardingtheirrelationshipswithoneanother,wemustdoitonapopulationbasis.

Apopulationcanbedescribedintermsoftheaverageandtheamountofvariationfromtheaverage,usuallyexpressedinstatisticaltermsasthemeanandstandarddeviation.Whenwedescribeaspecies,wemustmakemanysuchmeasurementsonmanyindividualsinordertogiveanaccuratestatisticalpictureofthepopulation.Fewsuchstudieshavebeendoneondogsbecauseofthe

ofthepopulation.Fewsuchstudieshavebeendoneondogsbecauseoftheimmenseamountofworkinvolved,particularlyifonehastoworkwithhandcalculatorsratherthancomputers.Mostattentionhasbeenconcentratedontheskull,partlybecausethisistheportionoftheskeletonwhichismostlikelytobepreserved,andpartlybecauseitshowsthemostvariation.

Dahr(1937)measuredtheskullsofStoneAgedogsofnorthern

38BEHAVIORPATTERNS

Europeandcomparedtheirdimensionswiththoseofmodernbreeds.Oneofthehighlyvariablecharacteristicsofcurrentdogbreedsistheshapeoftheupperjaw.(Figs.2.3,2.4,2.6).Bulldogshaveshort,broadjaws,andthoseofgreyhoundsarelongandnarrowcomparedwiththoseofotherbreeds.WhenDahrcomputedtheratioofsnoutlengthtobreadthoftheupperjawatthenarrowestpointandgraphedthisratioagainstskulllength,hefoundthattheStoneAgedogsallfellinaclosegroupinthemiddleofthemoderndogbreeds.Whenhemeasuredtheheightofthelowerjawfromtoptobottominrelationtothelengthoftherowofmolarteeth,heagainfoundthattheStoneAgedogsformedacompactgroupinthemiddleofthemoderndogbreeds.HeconcludedthattheseearlyEuropeandogsallbelongedinthesamepopulationandthatthemodernbreedpopulationshavedivergedinalldirectionsfromthem.

Anothervariablecharacteristicindogskullsistheshapeofthelowerjaw.ThewolvesstudiedbyDahrhadlongerandheavierlowerjawsthanmostmodernbreeds,althoughtheiraveragejawthicknesswasexceededbytheverylargebreedsliketheSaintBernard.Thelengthofthemolartoothrowisagoodindicatorofjawlength.NoteventheSaintBernardshaveaslongarowofmolarteethasdothewolves,sothatthewolvesstandatthetopendofthescalewithregardtojawsize.Itisobviousthatifwolveswereancestorsofmoderndogs,theremusthavebeenaveryearlyselectionforanimalswithsmallerjawsandteeth.Dahrwasinclinedtothinkthattheoriginaldogswereamiddle-sizedraceofwolveswhicharenowextinct.Judgingfromthetendencyforwolvestobesmallerinmoresouthernregions,thisisareasonablehypothesis,and,asmentionedearlierinthischapter,therearestillsuchwolveslivinginMesopotamia,indistinguishablefromcertainlocaldogsintheirskeletalcharacteristics.Werth(1944)arguesthattheprobableancestoristheIndianwolf(C.lupuspallipes)whichlivesinthatregion,andLawrence(1956)hasindependentlyreachedthesameconclusion.

DahrbasedmanyofhisconclusionsonmeasurementsmadebyWagner(1930).

DahrbasedmanyofhisconclusionsonmeasurementsmadebyWagner(1930).ThelattertraveledaroundthemuseumsinOslo,Copenhagen,andBerlin,measuringthedogs'skullsfoundthere.Someoftheseskullsdatebackasearlyas1863andmaynotreflectthemodernbreedsaccurately.HewasabletocollecttenormoreskullsFromtwelvedifferentdogbreeds,withsmallernumbersfromalargenumberofothers.Becauseofthepreferenceformalesamongdogowners,mostofthesemusthavebeenofonesex.Healsomeas-


uredseventeenwolfskullswhichhadbeencollectedinScandinavia,Greenland,andSiberiaandthereforemusthavecomefromthelargenorthernracesofwolves.

Wagnermadesomefortydifferentmeasurementsoneachskull.Ofthese,thebestmeasureofover-allsizeisthebasallength,thedistancebetweentheopeningintherearoftheskullfortheentranceofthespinalcordtothemostanteriorpointontheupperjawatthebaseoftheupperincisorteeth.Othermeasurementscanbegraphedagainstthis,asshowninFigures2.3-2.6.

Oneofthefirstthingswenoticeaboutlivingwolvesisthattheyseemtohavebroadheadsandheavyjaws.Ifwegraphthegreatestwidthacrossthecheekbones,whichincludesthejawmuscle,wefindthatwolves'skullsarewiderthanmostdogbreedsexceptfortheSaintBernards(Fig.2.3).Thebulldogbreedsalsohavemuchthesameproportions.Suchwidecheekbonesreflecttheskeletaleffectofhavingheavyjawmuscles.

Whenwegraphthegreatestbreadthoftheupperjaw(takenoppositethelargecarnassialteeth),wefindthatwolvesareessentiallynodifferentintheirproportionsfromnormaldogs,andthatSaintBernardshavejawswhicharefullyaswide(Fig.2.4).Thebulldogbreedsareoffinaclassbythemselveswithabroaderthannormalupperjaw,buttwootherbreedsareevenmoreextreme,theGreatDaneandGermanshepherd.Thesearethemostbroad-jawedofanybreedsandfarexceedthewolves.Itisinterestingthatthesetwobreedshavebeendevelopedinthesamepartoftheworld,andtheypossiblyhavesomecommonancestry.

Quiteadifferentpictureresultswhenwegraphthesizeofthemolarteethinrelationtothesizeoftheskull(Fig.2.5).Ontheaverage,wolvesnotonlyhavebiggerteeththananydogbreedstudied,buttheyarelargerinproportion.Inthemajorityofdogbreeds,toothsizeisverynicelycorrelatedwiththesizeofthe

majorityofdogbreeds,toothsizeisverynicelycorrelatedwiththesizeoftheskull,eveninthosebreedswithdeformedskullssuchasbulldogs.Thefewexceptionsarethosebreedswhichhavesomewhatsmallerteeththantheaverage.ThismeansthatWagner'swolfpopulationdifferedfromalldogpopulationsinonlyonerespect,theaveragesizeoftheteeth.Aswehaveseen,individualsinotherpopulationsoverlap.LittleRedRidingHood'sclassicremarktothewolf,"Whatbigteethyouhave,Grandma,"seemstobepartiallyjustifiedbythefacts.Itfollowsthatoneoftheearliestselectionproceduresfollowedbytheearlydomesticatorsofwolvesmayhavebeentopickoutanimalswithsmallteeth.

Thesemeasurementsalsobringoutthefactthatthereareonly

BEHAVIORPATTERNS

60

80

KX)

120140160180200BASALLENGTH(MM)

220240

Fig.2.3.—Skullwidthacrosscheekbonesasrelatedtoskulllength.Notethatbreedswithbulldogheads(havingshort,wideskulls)fallofftooneside.Wolveshavewideskulls,andcoyotesandjackalsnarrowones,butbothareexceededbyvariousdogbreeds.(MostdatafromWagner.)

KeytoBreeds(Figs.2.3-2.5)

BBA

BEABO

BOLBU

BUA

COCS

DDIDODP

Borzoi

Basenji

Beagle

Boxer

Bolognese

Bulldog

Bulldog,oldtype

CoyoteCockerspaniel

DachshundDingoDobermanDwarfpinscher

EG=Englishgreyhound

FBFT

Frenchbulldog

Foxterrier

CD=zGreatDaneGS=Germanshepherd

I=Icelandicdog

IW=Irishwolfhound

J=Jackal

L=Laplanddog

M=Mops(pug)

N=NewfoundlandNH=:Norwegianharehound

P=rPointerPE=PekinesePU=Poodle

RP=Rattlepinscher

S=SetterSB=SaintBernardSCH=:SchnauzerSH=Sheltie(Shetlandsheepdog)

W=WolfWH=Whippet(largeandsmall)

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BASALLENGTH(MM)

Fig.2.4.—Greatestwidthofupperjawrelativetoskulllength.NotethatGreatDanesandGermanshepherdshaveunusuallywidejaws.Coyotesandjackalshavenarrowjaws,butarenotasextremeassomebreeds.(MostdatafromWagner.)

140

120

or100o

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60

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*=n=10ormore

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BASALLENGTH(MM)

Fig.2.5.—Sizeofmolarteethrelativetoskulllength.Toothsizeandskullsizearehighlycorrelated,butinlargenorthernwolvestheteetharelargerthaninanydogsofsimilarsize.(MostdatafromWagner.)

42BEHAVIORPATTERNS

afewrealdeparturesfromnormalproportionsoftheskullinthedogbreeds.Oneoftheseisthebulldogtypeofhead,anditisinterestingthatthisdeformityappearsevenindwarfbreedslikePekingeseandpugs.AnotheristhebroadjawsoftheGreatDanesandGermanshepherds.Theheadsofthegreyhoundgroupareinbetterproportionthanonewouldexpect,andtheirbiggestvariationfromthenormisinthewidthbetweenthecheekbones.ThenarrowheadoftheborzoisandEasterngreyhounds,orsalukis,istheanatomicalresultofhavingnarrowcheekbonesandlessspaceforjawmusclesratherthanhavingthebrain

narrowcheekbonesandlessspaceforjawmusclesratherthanhavingthebraincasesqueezedtogether,asisoftenthought.

Anotherinterestingpointisthatthedwarfbreedshavebraincaseswhicharealmostaslargeasthoseofthebigbreeds.Reductioninbodysizehasaffectedthebrainverylittle,butthejawsandskullthicknesshavebeenreducedagreatdeal.Selectionforsmallsizehaschieflyreducedthosepartsoftheskullwhichareattachedtotheoutsideofthebraincase.Thisagainarguesthatthedogbreedsallcomefromonespecies,forifthedwarfanimalscamefromasmallspecies,onewouldexpectthatthepartsoftheirskullswouldbeingoodproportiontoeachother.

Stockard(1941)studiedtheskullsofvariousmodernbreedsofdogsandcametotheconclusionthatthebreedscouldbedividedintotwotypes,thosehavinglongskullsandthosehavingshortones.Theproportionsofthesaluki,GreatDane,SaintBernard,Germanshepherd,bassethound,anddachshundvarysomewhatfromeachotherbutareverydifferentfromsuchanimalsastheEnglishbulldog,Frenchbulldog,Bostonterrier,Pekingese,andBrusselsgriffon.Thelattergroupofanimalsaretheproductofageneorgeneswhichproducesabnormaldevelopmentofthehead.

Adifferentgeneorgroupofgenesmayshortenanddeformthelegs,ashappensinthedachshund.Itisprobablethatthemutationsfordeformedheadsanddisproportionatelyshortlegsoccurredseparatelyandwereusedindifferentcombinationsforthedevelopmentofvariousbreeds.Thuswehavetheboxerwithabulldogheadandnormallegs,aswellastheshort-leggedEnglishbulldog.Suchanimals,however,donotthrowmuchlightontheancestryandrelationshipsofthedog,excepttoindicatethatbreedswithbulldogheadsmayberelated.Eventhisisnotdefiniteproof,asthebulldogmutationmayhaveoccurredmorethanonceatdifferenttimesandplaces.

Thesestudiesshowthattherearenodistinctskull"types"excepttortheobviousdistortionsfoundinbulldogheadsandthenarrow

DOGS,WOLVES,ANDMEN

skullsofthegreyhoundbreeds.Wolvesoverlapwithdogsineveryskullmeasurementwiththepossibleexceptionofthesizeoftheteeth,andevenherelargedogsandwolvesoverlapasindividuals.Givenanunknownskull,abiologistcanidentifyitonlyintermsofprobabilitywithrespecttothemeasurementsofaknownpopulation.Someskulls,likethoseofChihuahuasand

measurementsofaknownpopulation.Someskulls,likethoseofChihuahuasandbulldogs,canbeidentifiedasdogswithverynearly100percentprobability,althoughevenherethereisalwaystheveryunlikelypossibilityofasimilarmutationinawildspecies.Onewaytoincreaseaccuracyistodetermineprobabilityonseveraldifferentmeasurements.Sofar,tinsmethodhasonlybeenusedtostudytherelationshipsbetweenpopulations.Jolicoeur(1959)studiedwolfpopulationsinthiswayandfoundthattheamountofoverlapwasinverselyproportionaltogeographicaldistance,andheconcludedthatmanyofthesubspeciesofNorthAmericanwolveswhichhavebeenidentifiedbythe"type"methodshouldbeconsideredpartofthesamepopulation.Suchananalysisisyettobeappliedtorelationshipsbetweendogbreeds,butwehaveeveryindicationthatthereisalargeamountofoverlapbetweenbreedsofthesamegeneralsize(Fig.2.6).

Tables2.1and2.2summarizetheresultsofmeasuringtheskullsofsampleanimalsfromthefivedifferentbreedsusedinourexperi-

TABLE2.1

AverageSkullMeasurementsofDifferentBreedsofDogs(tonearestmm.)*

Measurement

Condylobasallength

Basallength

Braincavitylength

Bizygomaticbreadth

Greatestjawbreadth

Smallestjawbreadth

Snoutlength

Lengthofmolartoothrow,Sizeofmolarteeth

FoxTerrier(2c7,29)

161152

161152

80

83

53

31

83

65

65

*Notethatsheltiesandfoxterriershavelongerskullsthantherest,andthatthesheltiesshowthesmallestmeasuresofanyinskullbreadth.

ments.ThesemeasurementschieflybringoutthefactsthattheShetlandsheepdogs(shelties)andwire-hairedfoxterriershavelongskullscomparedwiththeotherbreeds,andthatsheltieshavenarrowjawsinproportiontoskulllength.Thereisagreatdealofindividualvariabilitywithinbreedsandnoclearcutseparationbetweenthemexceptforthenarrow-jawedconditionofshelties(Fig.2.6).

BEHAVIORPATTERNS

TABLE2.2

RatiosofSkullMeasurementstoLengthofSkull(basallength)

Measurement

Braincavitylength

Bizygomaticbreadth

Greatestjawbreadth

Smallestjawbreadth

Snoutlength

LengthofmolartoothrowSizeofmolarteeth

FoxTerrier(4)

.53

.55.35.21.55.43.42

Anothermethodofdeterminingrelationshipsbetweenpopulationsistostudythereactionofbloodserumfromoneanimaltothatofanother(Boyden,1942).Thetechniqueistotakeserumfromoneindividualandinjectitintoanother,whichinduecoursedevelopsantiserum.Iftheserumofafoxisinjectedintoachicken,theanimalwilldevelopantiserumagainstfoxblood.Theexperimenterbleedsthechickenandextractstheantiserum.Henowtakesmoreserumfromthefox,mixesitwiththeantiserum,andmeasurestheamountofprecipitate.Thisgivestheamountofreactionagainsttheoriginalfoxserum,orantigen.Ifhemixesdogserumwiththeantiserum,thereisasmalleramountofprecipitate.Comparisonofthetwofiguresprovidesanestimateofhowalikethetwospecies

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00

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50

40

30

30

o=Basenji•=Beaglex=Cocker

+=Sheltie■=FoxTerrier

COYOTES

X,--

-jT++

JACKALS(AUREUS)

feife)I70"[fel

bo

100110120130140I

BASALLENGTH

Fig.2.6.—Relativebreadthofupperjawinfivemodernbreeds.NotethatstraightlinewillcutoffallShetlandsheepdogsfromtherestbutthatthereagreatdealofoverlapbetweentheotherfourbreeds.


maybe.Usingthismethod,PaulyandWolfe(1957)comparedthreecaninespeciesandobtainedthefollowingfigures:dogwithwolf,88percent;dogwithfox,50percent;foxwithwolf,52percent.Dogsareobviouslymorelikewolvesthanfoxes.Duerst(1942),however,experimentingwithonewolfandonejackal,foundthatthetwoweresimilarlyrelatedtodogs.

Thelimitationsofthemethodarethatitmustbedonewithextremecare,assmallamountsofcontaminationcanproduceverygreatvariationinresults.

smallamountsofcontaminationcanproduceverygreatvariationinresults.Also,mostresultsnowavailablearebasedonantiseraandseraobtainedfromonlyonememberofeachspecies.Thepopulationapproachisstilltobeappliedtothistechnique,anduntilthisisdoneitprovidesonlytentativeevidence.

HISTORICALEVIDENCE

Byandlarge,historianshavebeenlittleinterestedindogsandrefertothemonlyinpassing.Forexample,Trevelyan,inhisEnglishSocialHistory(1943),saysthatacomplaintwasmadeinParliamentin1389thatlaborersandservantskeptgreyhoundsandotherdogsandwerewastingtheirtimehunting.Asaresultalawwaspassedtopreventpeoplewithlowincomesfromkeepingsportingnetsordogs.Suchcasualrecordsindicatethatdogswerepopularandoftenusedinhunting,particularlybythegentry.

InthesamecenturyChaucerwrotehisCanterburyTales,whichcontainvividdescriptionsofcontemporarycharactersandtheiroccupations.ThePrioresskept"smallhounds''ascompanions,andtheMonkwasahuntingman—"greyhoundshehad,asswiftasfowlsinflight."TheWifeofBathmetaphoricallydescribesawoman'sover-fondnessforaman:"Forasaspaynelshewillonhimlepe,"indicatingthatexuberantaffectionwasascharacteristicofthespanielsofthefourteenthcenturyasitistoday.

TheearliestEnglishbookondogswaspublishedin1576,duringthereignofQueenElizabethI.ThiswasactuallyatranslationofapaperinLatinwrittenbyJohannesCaius,a"DoctorofPhisickeintheUniversitieofCambridge,"forwhomthepresentCaius(pronounced"Keyes")Collegeisnamed.ThepaperwasoriginallywrittenattherequestofConradGessner,theSwissnaturalist,whowantedinformationregardingtheEnglishbreedsofdogs.

CaiuswasobviouslyinfluencedbythecontemporaryEnglishsocialsystem,forhesaysthattherearethreekindsofdogs,agentlekindservingthegame,ahomelykindfornecessaryuses,andacurrishkind,"meeteformanytoys."Huntingwasreservedfortheno-

46BEHAVIORPATTERNS

bilityindogsaswellasinpeople.However,Caiusdescribesmanydogswhicharethecounterpartsofmodernbreedsaswellasmanywhichhavedisappeared.

Classifyingdogsaccordingtotheiruse,hefirstdescribesthehoundsashunting

Classifyingdogsaccordingtotheiruse,hefirstdescribesthehoundsashuntingbyscentandhavinglargebagginglipsandhangingears.Heplacesthebloodhoundinaseparategroupbecauseitwasusedtochasebeaststhatwerewoundedandtotrackdownthieveswhohadstolenmeat,particularlyontheScottishBorder.Evenatthattimebloodhoundshadanunusualreputationforbeingabletofollowatrail.

Instillanothergroupwerethe"gasehounds,"usedforhuntingbysight,andhencethename.Suchbreedshaveapparentlydisappeared.Greyhoundswereusedsomewhatdifferently,incoursing,orpursuitbysight,actingandappearingverymuchliketheirmoderncounterparts.

Terriers,derivingtheirnamefromtheFrench"terre,"werebredtocreepintothegroundanddriveoutsmallanimalslikefoxesandbadgers.The"Spaniells"originallycamefromSpainandwereusedbothforhawkingandhuntingbirdswithnets.Agroupofcloselyrelatedbreedswerethesetters.AsCaiussays,asetterwassupposedtofindbirds,lieontheground,andcreepforwardlikeaworm,lyingdownnearthem.Thenetwasthenpreparedandthedog,onsignal,wouldriseandfrightenthebirds,whichthenflewintothenet.Thisdescriptionofsettingbirdsforthenetissomewhatdifferentfromthatgivenbyotherwriters,andperhapstheywereused

inseveraldifferentwavs.

j

Hementionsthe"Spaniellsgentle"asneat,prettydogs,probablyreferringtosomeofthetoybreedsliketheKingCharlesspaniel.Asectionisreservedforthe"homely"dogs,includingshepherddogsandmastiffsorbandogs.Thislastnamereferstothefactthataguarddogwasusuallykepttiedupbyabond,orchain.Finally,thereweremongrels,whichCaiussaid"keepnottheirkind,"includingthe"turnspits,"usedonatreadmillwhichturnedthemeatbeingroastedoverafire.

Amongbreedswhichhavenowdisappearedwerethe"lvemmer,"whichwasmidwaybetweenharriersandgrevhounds,the"tumbler,"usedforhuntingrabbits,andthe"thecvish"dog,whichdidnotbarkandwasusedbypoachersforhuntinginthedark.Ifthisreportiscorrect,barklessnesshasoccurredinbreedsotherthanthemodernbasenji.

Wecanseefromtheserecordsthatsonicoftheprincipalbreedsofmoderndogs

Wecanseefromtheserecordsthatsonicoftheprincipalbreedsofmoderndogswerealreadyestablishedfourhundredyearsago,


andthattheEnglishwerealreadyimportingbreedsfromothercountries.Howthebreedswererelatedtoeachotherandhowmuchcrossingwasdonebetweenbreedswehavenowayofknowingexceptbyinference.

Anotherbookondogswaspublishedin1686,overacenturylater.RichardBlome'sTheGentleman'sRecreationwasasortofencyclopedia,thefirstpartcoveringtheartsandsciencesfromgrammarandrhetoricthroughhorography,or"sundialling,"tofortificationandheraldry,andthesecondincludingarticlesonvarioussortsofhuntingandotherspecialoccupationsofacountrygentleman.Aswasthecustominthosedays,theexpenseofprintingwasbornebywealthybenefactors,andBlomehonoredthembypicturingtheircoatsofarms.ThebookwasauthorizedbyCharlesIIin1682,butdedicatedtoJamesII,whowasoneofthesponsors.Amongthe228others,thereappearsthenameofGeorge,LordJeffries,heofthe"BloodyAssizes"thatfollowedtheDukeofMonmouth'sshort-livedrebellionin1685.

ButBlomewasnotinterestedinpolitics.Inhisbookhedescribesseveralvarietiesofbeagles:thesouthernbeagle;the"fleet,northern,orcat"beagle,somewhatsmaller;and,finally,averysmalltype,thesizeofalady'slapdog,sometimesusedforhuntingconeys(theoldwordforrabbits)andhares.

LikeCaius,hedescribesterriersassmalldogsusedforfollowingthefoxorbadgerintotheearthandsaysthatadogbredoutofabeagleandamongrelmastiffmakesagoodterrier.Healsomentions"tumblers"and"lurchers,"forhuntingconeys;greyhounds,forcoursing;andbloodhounds,usedfor"harbouring"astag,i.e.,locatingtheplacewherethestagspentthenight,or"harboured."

Hisgreatestenthusiasmwasreservedforspaniels,whichwereemployedfor"springing"andretrievingoffowl.

SpanielsbyNatureareveryloveing,surpassingallotherCreatures,forinHeatandCold,WetandDry,DayandNight,theywillnotforsaketheirMaster.TherearemanyProdigiousRelations,madeinseveralGraveandCredibleAuthors,ofthestrangeAffectionswhichDogshavehad,aswelltotheirDeadandlivingMasters;butitisnotmybusinessoftakenoticeofthemhere;buttoapply

Masters;butitisnotmybusinessoftakenoticeofthemhere;buttoapplymyselftotheSubjectinHand.

Wecanconcludethatdogstorieswereaspopularinthosedaysastheyareatpresent,andmanyofthemjustasdifficulttobelieve.Blomegoesontowritechaptersontheuseofwaterandlandspanielsinthesportoffowling.Hisdescriptionsoftrainingwoulddocredittoanymoderndogbook.

48BEHAVIORPATTERNS

Ofalldogsthereisnonesofitandpropertobemadeasettingdogasalandspaniel,byreasonoftheirnaturalinclinationtorangingandbeatingaboutafield;butanydog,whetherawaterspanieloramongrelbetwixtboth,oralurcherortumbleroranydogthathathaperfectgoodscent,andnaturallyaddictedtothehuntingoffowl,maybebroughttobeasetter.

Thelandspanielwasfirsttaughtto"couchandlieclosetotheground,"thentaughttoliestillwhileabirdnetwasdraggedacrosshim,thentaughttoassociatelyingdowmwiththescentofapartridge(whichBlomesayscanbeduplicatedbyaboiled"bullock'sliver").Intheactualhunt,thespanielfirstquarteredtheground.Whenheindicatedbyhiseagernessandwagginghissternthathehadlocatedthebirds,hewasorderedtoliedownandremainuntilthenetwasthrownoverbothhimandthebirds.Inhuntingpartridge,thetechniquedescribedbyBlomeinvolveddrawinganetoverthecoveybeforeittookflight.

Blomecallstheactualdiscover}'ofthebirds"makingapoint"andremarksthat"somedogswillstandupintheirsetting,wrhichisagreatfault."Aftershotgunswereinvented,birdswerenolongertakenwithanetandnewdogsweredevelopedfromthelandspanielswhichsimplystoppedandpointedwhentheylocatedbirds.Thuscrouchingbecameafaultinitsturn,andallmodernsettersarereallypointers.Onlyinthecockerspanielsdoestheoriginaltendencytocrouchremain,andthesebreedsreadilycrouchandcrawlontheirbellieswhenthreatened.Themodernspringerspanielsweredevelopedto"spring,"orflushbirds;andcockers,whentheyareusedforhunting,areusuallytaughttoflushthebirdsratherthantopoint.However,theystillretaintheiroldcapacityforlearningtocrouch.

Incontrasttospaniels,thebasenjibreedhasashortwrittenhistory.AccordingtoVictoriaTudor-Williams(1946),aprominentEnglishbreeder,basenjiswerefirstsuccessfullvimportedintoEnglandin1937.ThetwoanimalsusedtoformthefoundationstockfortheJacksonLaboratorywerebothdescendedfromfive

thefoundationstockfortheJacksonLaboratorywerebothdescendedfromfivebasenjisimportedintoEnglandinthatyear.Comparedwithmostpurebreddogs,theircoefficientofinbreedingwassurprisinglyhigh(.23,ascalculatedfromtheirpedigreewhichextendsbacktotheirfiveimportedancestors).ComparativefiguresforthefoundationstocksoftheotherfourbreedsareshowninTable2.3,basedonavailablepedigreerecordscoveringatleastfourgenerations.

WeareindebtedtoDr.JamesP.Chapin(1958)oftheAmerican

TABLE2.3

CoefficientsofInbreedingofFoundationStock*

Basenji23

Beagle00

Cockerspaniel01

Sheltie06

Foxterrier00

•Cockersincludeonlythoseanimalsusedinthecrosswiththebasenji.

MuseumofNaturalHistory,whoobservedthisbreedwhileontheMuseum'sCongoexpeditionsin1909-15andlateryears,foradescriptionofbasenjisintheirnativehabitat.Theyoriginallyhadawidedistribution,fromtheFrenchCongoandcentralCongobasinintothesouthernSudanandUganda,andperhapsfurther.TheywereownedandusedinhuntingbvPvgmiesandseveralotherAfricantribes.RecentlytheyhavebeguntocrosswithdogsbroughtinbyEuropeanresidents,andpurestrainsmaybedifficulttofindinthefuture.ThereisnoindicationofcrossingintheJacksonLaboratorystock,inwhichinbreedinghasneverrevealedconcealedrecessivesbelongingtootherbreeds.

Thename"basenji"intheLingalatradedialectofthecentralCongomeans"peopleofthebush."Evidentlytheearlyexplorersaskedthenativesthenameofthebreed,andtheyrepliedthatthoseweredogsbelongingtothebushpeople.ChapinsaysthatthePygmiesoftheIturiforestusedbasenjisforhuntinginmanyways.Thesetribesfrequentlyhuntedwithnets.Menanddogswouldgothroughtheunderbrushanddrivesmallantelopesalongthegametrailstowhereanethadbeenset.Sometimesbasenjiswereusedforflushingbirds,which

anethadbeenset.Sometimesbasenjiswereusedforflushingbirds,whichwouldthenflyintothetreeswheretheycouldbeshotwitharrows.Theywerealsoemployedintrackingsmallgame,andadogwhichhadakeensenseofsmellwashighlyvalued.Thusthebasenjisareageneral-purposehuntingdoganddonotfitintoanyoftheconventionaldivisionsoftheEuropeanbreeds.

Accordingtothebreedstandards,basenjisarebarklessdogs.ThoseinAfricaoccasionallybark,butonlywhenextremelyexcited.Atnightinthenativevillagestheyoftenmakeatremendousnoise,whichChapindescribesasyodellingandwailing.Similarbehavioroccurredinourkennels.

WehavenotbeenabletogetanyauthenticinformationregardingthebreedingseasonintheirnormalhabitatneartheEquator,and

perhapsthereisnoneinthisregionofalmostconstantdaylength.Inthenorthtemperatezone,basenjisbreedonlyonceayear,closetothetimeoftheautumnalequinox.

Livinginthesameregionsasjackals,basenjishavehadamuchbetteropportunityforcrossingwiththemthanhavemostotherbreeds.Thepeculiarvocalizationofbasenjislendssomeweighttothishypothesis.However,jackalnoisesaremuchmoreelaboratethanthoseofthebasenjianddifferentinmanyways.VanderMerwe(1953)saysthattheAfricanblack-backedjackal"yelpslikeadogwhenstartled,"butgivesanundoglikesoundwhencornered:"ke-ke-ke-kek."Thedangersignalwhenpupsarepresentisasoft"wuf."Inthematingseasonthefemalegivesa"shrillbutheartylaugh/'andthemaleanswerswithalonghowl.Thejackalhasahuntingcryorhowldescribedas"ieaaaa-iea-iea-iea"or"nieaaaaa-niea-niea-niea."Whetherjackalandbasenjinoiseshavesomesimilarityremainsanopenquestionthatwillbeansweredonlywhendetailedanalysisofthesesoundscanbemadewiththesoundspec-tograph.

Inotherrespects,thebehaviorofbasenjisandjackalsisquitedifferent.Jackals,likecoyotes,arenotstronglysocialanimals,andtheusualadultgroupisamatedpair.Theyarerarelyfoundinpacks.Basenjis,ontheotherhand,runinco-ordinatedgroupswhenraisedinlittersandbehavemorelikepackanimals.

UsinghistoricalinformationandsuchmodernhistoryasisincludedintheAmericanKennelClubDogBook,wecansaythatmodernbreedshaveoriginatedinfourprincipalways.Thefirstoftheseisthemoreorlessaccidentaldevelopmentoflocalvarieties,suchasthedevelopmentoftheLabradorretrieverinmoderntimes(Smith,1945).Asecondwayinwhichbreedshaveoriginatedis

inmoderntimes(Smith,1945).Asecondwayinwhichbreedshaveoriginatedisbyimportinglocalvarietiesfromdistantparts.ThusthefirstchowwasbroughtfromChinaabout1780(White,1842),andthefirstbasenjiswerebroughttoEnglandin1937.Third,manymodernbreedshavebeendeliberatelydevelopedbycrossbreedingandselection.Amongthesearethefoxterrier,developedtohelpgetfoxesoutoftheirdenswhenthesportoffoxhuntingbecamepopular,andthegoldenretriever,whosebasicstockreportedlywasbroughttoEnglandbyagroupofRussiancircusperformers.TheShetlandsheepdogs,orshelties,wereoriginallysmallnondescriptdogslivingintheShetlandIslands.ThesewerecrossedwiththelargeScotchtolliestoimprovetheirappearanceandlatercrossedwithsomesmallerbreedsinordertoreducethesizeagain(Coleman,1943).Thesheltiebreedersarenowselectingforasmalldogwith

thegeneralappearanceofacollie.OthernewlydevelopedbreedsaretheAiredaleandDobermanpinscher.Finallytherearethebreedswithknownancienthistories,suchasthesalukisoftheMiddleEast,whichtheCrusadersprobablybroughtbacktoEnglandtobetheancestorsofEnglishgreyhoundsandtheirrelatives.Spanielsandhoundsalsohavehistoricalrecordsdatingbackmanycenturiesandhavebeensubdividedintoseveralmodernbreeds.

Incidentally,theclassificationschemeoftheAmericanKennelClub,aswellasthesomewhatdifferentoneoftheKennelClubofGreatBritain,isnotbasedoncommonancestry,butonsimilaruses(Scott,1963Z?).Forexample,thenon-sportingbreedsincludesuchanimalsofwidelydifferentancestryasthepoodles,descendedfromhuntingdogsofwesternEurope,andthePekingese,whicharetoydogsimportedfromChina.ThusthemoderndogfanciersfollowCaiusinclassifyingbreedsbyfunctionratherthanorigin.

EVIDENCEFROMGENETICS

BeginningwithDarwin,studentsofheredityhavewonderedhowthedomesticdogcouldbesovariable,andDarwinhimselfthoughtthatdogsmusthavebeendescendedfromatleasttwospeciesinordertoaccountforthevariationofmodernbreeds(Darwin,1859).

AtthattimetherewasverylittleaccurateinformationaboutthenatureofwolvesandnoneconcerningthepossibilityofvariationprovidedbysimpleMendeliangenetics.Recentstudiesshowthatthewolfisahighlyvariablespeciesinthewild.Murie(1944)couldrecognizeindividualsasbeingdistinctlydifferentevenwithinthesamepack.Jolicoeur(1959)findsgreatvariationinthecolorandskullmeasurementsofCanadianwolvesfromonelocalitytoanother.Youngand

skullmeasurementsofCanadianwolvesfromonelocalitytoanother.YoungandGoldman(1944)pointouthowdifferentwolvescanbeinphysicalmeasurements.TherewereendlesslocalvarietiesbeforewolveswereexterminatedovermuchofNorthAmerica,andthenorthernwolvesweremuchlargerthanthesouthern.Thismeansthatwolvesarenaturallyhighlyvariableandcanbetrulycalledapolymorphicspecies.Theoriginaldomesticatorsofthewolfthushadplentyofvariabilityfromwhichtochoose,exceptintheproportionsoftheskeleton,whichappeartobehighlyuniform(Hil-debrand,1954).

Aswehaveseen,thewidevariationinstructureindogbreedsisproducedbyarelativelysmallnumberofmutationssuchasthebulldoghead,shortlegsandlopears.Inadditiontothese,thereareallthevariationsincoatcolorandhairlengthandtexture.

52BEHAVIORPATTERNS

Finally,thereisagradedseriesinbodysize,fromthedwarfthroughmiddle-sizeddogstothegiantbreeds.Ifweassumethattherearefivedifferentmutationsofbodyformandperhapstenofcoatcolor,wecouldobtainfromthematotalof215combinationsoftraits.Thisamountsto32,665.Evenwithonly10mutations1,024combinationsarepossible,farmorethanthefewhundredknownvarietiesofdogs.Itisnotunreasonabletosupposethatasmanvas10to20majormutationshaveoccurredandpersistedindogsinthelasttenthousandyears,especiallvinviewofthetendencyofpeopletobeinterestedinandattempttopreservenewandfreakishanimals.Inshort,mutation,selection,andMendeliangeneticswillaccountforthevastamountofvariationindogswithouttheneedtosupposeadualancestry.Asamatteroffact,thedifferencesbetweenspeciesinthegenusCanisarenotthesortwhichdifferentiatedogbreeds.Therearenowildspecieswithlopears,curlytails,orshortlegs.Acrosswithanewwildspecieswouldbringinrelativelylittlevariationofthistype.

Amoreprecisewayofobtainingevidenceonbasicgeneticrelationshipswouldbetomakeadetailedstudvofchromosomesindifferentdogbreedsandwildspecies.Chromosomestructureandnumberaffectthecapacitytohvbridize.Ifanimalsfromtwospeciesmate,theiroffspringreceivesasetofchromosomesfrombothparents.Theembryomaybeabletodevelopevenifthetwosetsdonotmatcheachother,butwhenitsgermcellsareformed,thechromosomesmustpairexactlyintheprocessofmeiosisorthegermcellswillnotdevelop.Thusinacrossbetweenthehorseandthedonkey,thehvbridmulesareusuallysterile.

acrossbetweenthehorseandthedonkey,thehvbridmulesareusuallysterile.However,onceinaIons;whilechromosomeswillbelostoraccidentallvarrangedinacompatibleorder,sothatsomemuleshavebecomeparents(Anderson,1939).SterilitvoftheFihvbridisthusanindirectindicationofchromosomeincompatibilityandthefactthattheparentsreallybelongtotwodifferentgeneticpopulations.

InthegenusCanis.Iljin(1941N)crosseddogsandwolvesandcarriedtheiroffspringtothesecondgenerationwithnoindicationofsterility.Thisistheonlvcontrolledgeneticexperimentwithhybrids,butaccordingtonaturalists'reports(Grav.1954),dogshavebeencrossedwithbothcovotesandjackalstoproducefertileFihybrids.TheresultwithjackalsisinconsistentwithMatthey's(1954reportofchromosomedifferences,andthisreportneedstobeverifiedbydirectexperiment.

Whiledogshavebeencrossedwitheven-othermemberoftheiiisCanis,wolveshavenotbeencrossedwitheithercoyotesor


jackals,probablybecauseofdifferencesinsize.Seitz(1959)madeasuccessfulmatingbetweenacoyoteandjackalbutdidnotdeterminethefertilityoftheFihybrid.Atthispointwecannoteliminatethepossibilitythatatsomepointdogshavebeencrossedwithaspeciesotherthanwolves,andthatsomeoftheintroducedgeneshavepersisted.

TABLE2.4HybridsReportedbetweenSpeciesortheGenusCants

Withthemethodsofstudyingchromosomesrecentlydevelopedinstudiesofhumangenetics,itshouldbepossibletomakeaccuratecomparativestudiesofthegenusCanis.Suchinformationshouldthrowconsiderablelightontherelationshipsbetweenthedoganditswildrelativesaswellasthosebetweenthedogbreeds.However,thismustbedoneonpopulationsratherthanonscatteredindividualsinordertoprovideworthwhileevidence.

Littleinformationonthispointisnowavailable.Thedogitselfhasaverylargenumberofchromosomes,78inall,butnoonehasexaminedthechromosomesofthewolf.Theyellowjackal(C.aureus)ofAsiaandNorthAfricahasonly74chromosomes(Matthey,1954),whichindicatesthatitcouldnotbecloselyrelatedtothedogbreedsthathavebeenstudiedsofar.Ahmed(1941)studiedthechromosomesandtheirbehaviorinSealyhamterriers,spaniels(breednot

chromosomesandtheirbehaviorinSealyhamterriers,spaniels(breednotreported),andacrossbetweenspanielsandManchesterterriers.Alltheanimalshadthesamenumberofchromosomes,78,butAhmedfoundindicationsofdifferencesinappearanceandbehaviorofthechromosomesinthedifferentbreeds.ThesewereallbreedsfromtheBritishIsles,anditispossiblethatlesscloselyrelateddogsmightshowmoreextremechromosomaldifferences.

OtherspeciesofCanidaearequitedifferentfromthedog(Matthey,1954).Theredfoxhas38chromosomes,andanotherspeciesoffox(Vulpesruppelli)has40.Therare"raccoondog"ofEuropehas42,whilethefennec,asmallfoxlikeanimalofAfrica,has64chromosomes.Summingupthepresentevidence,wecanonlysaythatthereisnonecessitytopostulatemorethanonewildancestralspecies,andthemostlikelycandidateisalocalvarietyofthewolf,Canislupus.

54BEHAVIORPATTERNS

CONCLUSION

Noonecanaccuratelyreconstructthepast,andparticularlytheprehistoricpast.Themostthatwecandoistotaketheavailableevidenceanddrawaprobableconclusion.Fromwhatwehaveseeninthischapter,alltheevidencepointstowardthewolfasthemostprobableancestorandclosestrelativeofthedomesticateddog.

Wecannotsayexactlywheredomesticationfirstoccurred,forthearcheologicalstudyofprehistorichumanremainsanddomesticanimalsisfarfromcomplete.However,theoldestauthenticskeletonsofdogsarefoundinDenmark,anditseemslikelythatthefirstdomesticdogswereproducedsomewherenearbyinCentralEurope,orpossiblyinthe"fertilecrescent"ofMesopotamia.Oncedomesticated,theyspreadslowlyovertheworld.Thefirstdogwasavaluableinventionforaprimitivepeople,andwecansupposethatneighboringtribesheardofthesenewanimalsandgraduallyacquiredthem.

Presentknowledgedoesnotgiveusanaccuratedateforwhenthisoccurred.ThedogsofDenmarkhavebeendatedasearlyas8000B.C.,butnotbymodernradiocarbonmethods.Eventhistechniqueisstillinitsinfancy,andmanymorefactsareneededbeforewecometofinalconclusions.Assumingthattheabovedateiscorrect,itwasfifteenhundredyearsbeforedogsspreadtoMesopotamia.In6750B.C.,theprimitivefarmingvillageofJarmoinIraqhaddomesticatedgoats.Atthesamesitewasfoundadoglikefigurinewithacurlytail.IntheruinsoftheJerichoof6500B.C.,therewereactualdogbones.Afteranotherthree

oftheJerichoof6500B.C.,therewereactualdogbones.Afteranotherthreethousandyears,dogshadspreadtoneighboringEgypt.

FromEgyptthedogspreadsouthwardandeastwardintotropicalregions,becomingadaptedtoexistenceinahot,humidclimatewhichtheirwolfancestorshaveneverseen.Werth(1944)arguesthatthebasenji,dingo,andcertainmedium-sizeddogsofPapuaandtheEastIndiesaredescendantsoftheseearlysoutherndogs.Theyareoutwardlysimilarinappearance,beingusuallyyellowincolorwithshorthair,prickears,andcurlytails.Whilesuchsuperficialsimilarityisnotperfectproof,thehypothesisisaplausibleone.

FromCentralEuropedogsspreadnorthwardandgotintothehandsofhuntingtribes.TherearenodogremainsfromtheEnglishhuntingvillageofStarCarrdatedat7200b.c,butdogseventually


wereacquiredbyEskimosandtheireasterncousinswhowentovertheBeringStraitintoNorthAmerica.

Wecanconcludeonthebasisofpresentfactsthatthedomesticationofthedogtookplaceabout8000b.c.Thismeansthatthedoghashadadomestichistoryofsometenthousandyears,andthatsomefourtoeightthousandgenerationsofdogshavelivedupontheearthwithabundantopportunitiesformutationsandgeneticvariationstooccur.

Astohowdomesticationfirsttookplace,wecanonlyguess.Probablyithappenedverysimply.InAlaskaandothernorthernareaswherepeoplestillliveclosetowolves,wolfcubsareoftencapturedeventoday.Someofthembecomeacceptableaspetsorsleddogs.Primitivepeopleseverywhereintheworldfrequentlyadoptyoungbirdsormammalsaspets.WecansupposethatwolveshungaroundtheprimitiveagriculturalvillagesofEuropescavenginganywastefoodorbonesthatwerethrownaway,andthatthehumaninhabitantsmightfrequentlycomeacrosswolfcubsinthespring.Menseemtohavedomesticateddogsaboutthesametimethattheybegantoliveinpermanentvillages.Contrarytowhatonemightexpect,thereisnoevidencethatearlierhuntingtribeshaddogs(Werth,1944),andtheusefulnessofthedogasahuntinganimalwasprobablydiscoveredlater.

Wecanimagineawolfpuppygrowingupinavillage,fedatfirstandlaterexistingonscraps.Aswolvesanddogsstilldotoday,itbecameadoptedinto

existingonscraps.Aswolvesanddogsstilldotoday,itbecameadoptedintohumansocietyandestablishedaterritoryarounditshome.Itssensitivitytotheapproachofstrangeanimalsandpeopleatnightmusthavebeenimmediatelyvaluable.Later,whengoatswerealsodomesticated,itsdog-likedescendantscouldwarntheirownersoftheapproachofwildwolveswhichmightattacktheherd.

Atfirsttheremusthavebeensomeconfusionbetweentamewolvesandwildones,butveryearlyindomesticationamutationforcurlytailmusthaveoccurred.Wildanddomesticwolvescouldthenbeeasilytoldapart.Also,theremusthavebeenanearlyselectionforanimalswhichcouldbemoreeasilycontrolled,andthismeantthedevelopmentofsmallormedium-sizedwolveswithsmallerandlessdangerousteeth.

Thusthebasictraitsofdomesticdogswereestablished.Asdogsspreadfromvillagetovillagethroughouttheworld,therewasanidealopportunityforwhattheevolutionistscalladaptiveradiation,aphenomenonwhichalwaysoccurswhenagroupofanimalsmoves

intoavacanthabitat(Fig.2.2).Suchconditionsareidealforthesurvivalofvariationsbecausewholenewpopulationscanarisefromafewvariableindividuals.

Asaresult,eachvillagehadasmallpopulationofdogssomewhatdifferentfromthoseoftheothers.Subdivisionsintosmallpopulationswouldbeidealforfurthergeneticchange.Allthis,coupledwiththehumantendencytoselectandsaveanimalswithindividualpeculiarities,couldaccountfortheoriginofdifferentbreeds.Therearemanyearlyhistoricalreferencestolocalitiesfamousfordifferentdogs,suchastheMolossianhoundsofclassicalantiquity.

Atthesametime,wecannotconcludethateachbreedwascompletelypureandseparatefromthetimeofitsorigin.Onthecontrary,thepromiscuoushabitsofdogs,aswellasthedeliberatecrossesmadebytheirowners,tendedtomakealldogsinagivenareasomewhatrelatedtoeachother.Itisonlywithinthelastcenturythatbreeders'clubshaveattemptedtoproducepurebreedsofdogs.Evenso,thehistoryofthemodernEuropeanbreedsshowsthatmanyofthemweredeliberatelyproducedbycrossingseveralbreedstogethersothatwhileeachbreedmayhavecertaindistinctivecharacteristics,Europeandogsareactuallyinterrelatedinmanyways.

Sizepreventslargedogsfrominterbreedingwithverysmallones,butwhenwe

Sizepreventslargedogsfrominterbreedingwithverysmallones,butwhenweplacesizemeasurementsonagraph,weseethatthereiscontinuousvariationfromtheChihuahuatotheGreatDane,withthepossibilityofcrossinganywherealongthelinebetweenanimalsofsimilarsize.

Allthismeansthatdogsbelongtoonlyonespecies,asLinnaeusoriginallysupposed,inspiteoftheirenormousphysicalandbehavioralvariability.Theonlyotheranimalwhichshowsanythinglikethesamedegreeofvariationismanhimself.Dogsaredogsandarebasicallyrelatedtowolves.Thisistrueoftheirbehavioraswellastheirphysicalstructure,aswillbeseeninthenextchapter.

THESOCIALBEHAVIOROFDOGSANDWOLVES

INTRODUCTION

Anyonewhoownsadogisimpressedwiththeextraordinarydegreetowhichsuchananimalbecomespartofahumangroup—docile,affectionate,andprotective.Onemaywellwonderwhetherthefamilypetisreallydescendedfromawolfand,evenifso,whetherselectionhasnotchangedhisbehaviorsocompletelythatitisnowalmosthuman.

Weattemptedtoanswerthisquestionbyobservingwhatgroupsofdogsdidwhenoffbythemselveswithnohumanbeingsaroundthem(Scott,1950).Wewerefortunateinhavingplentyofspace,andforequipmentwehadthreeone-acrefieldssurroundedby7-footwoodenfences.Thedogsinsideonlysawpeoplewhocamecloseenoughtobevisiblethroughthecracks,andwemadesurethishappenedasseldomaspossible.Webuiltsomeobservationplatformsintheneighboringtreesandfromthesevantagepointswatchedwhatthedogsweredoingforoverayear.Inonepenweputalitterofyoungfoxterriers,inanotheralitterofScottishterriers,andinathirdalitterofbeagles.Asthemonthspassed,puppieswerebornintwoofthegroups,andwewereabletowatchthebehaviorofthedogsandtheiroffspringastheylivedunderconditionsofconsiderablefreedom.

Oneofthedifficultieswithstudyingdogsisthateveryoneknowsdogs.Eachofustriedtowritedownwhatthedogsdid.Beingwell-trainedscientists,wetriedtobeasaccurateandconscientiousaspossible.OurfirstnotesusuallyindicatedthatdogBimovedacrossthefield,whiledogB2moveddownthefield,withverylittle

57

57

otherinformation.Weweresofamiliarwiththedetailsofdogbehavior,suchastailwagging,sniffingtheground,etc.,thatweoverlookedthementirely.Astimewenton,however,webegantonoticethesedetailsandrealizedthatthesewerepreciselythekindofinformationwewanted.Wedidnotcaresomuchwhereadogwentashowhedidit.Andsoinsubsequentnoteswebegantodescribesuchdetailsashowamalemightapproachafemaleandsniffhertailwhileshegrowledathim.Togiveanactualexample:"B7againplayswithpup.Puprollsover—cries.B7sniffspup—pupruns—pupwagstail—criesloudly.B7playingwithit—chasingit.PupgrowlsatB7."

Thuswehadthebeginningofacollectionofthekindsofbehaviorpeculiartodogs.Indeed,thisisthefirsttaskinstudyingthebehaviorofanyanimal.Itisdonethroughobservationandisprimarilyacollector'sjob,agooddeallikecollectingspecimensofthevariouskindsofinsectsorotheranimalsinanarea.Insteadofmakingabiologicalsurveyofaregion,weweremakingapsychological(orethological)surveyofbehavior.

THEUNITOFBEHAVIORSTUDYISTHEBEHAVIORPATTERN

Asweleafthroughthenotesweoftenfindsuchitemsas:"DogTiscratched."Usuallytheobserverdidnothavetimetodescribethisindetail,butthephraseconjuresupapictureofthedogliftingonehindlegandscratchingitsshoulder,neck,oranyregionthatitcanreachinthisway.Anyonewhohashadapetdogknowsthatyoucanproducethisbehaviorbyticklingthedogalongitsside,settingoffasimplereflexwhichthedogcannotcontrolinanyvoluntaryway.Thisappearstobeasimpleandunifiedpieceofbehaviorhavingthegeneralfunctionofgrooming.

Anobservantdogowneralsoknowsthatthisisnottheonlywayinwhichadogrespondstoanitchingspot.Ifitisonhishindleg,hemayattackitwithhisteeth;ifitisonhisback,hemayrolloverandoverontheground.Thuswehavealistofthreealternatewaysinwhichdogsrespondtothesamegeneraltypeofstimulus.

Inanothernotewefindthat"someonewalkeddowntheroad.Bi>rantothefenceandbegantobark."Hereisanothersimplepieceolbehavioi—barking.Theeffectwastoarousealltheotherdogsinthegroup,whichrushedoverandbegantobarkalso.Itlooksasifbarkinghasthefunctionofanalarmsignal.AnothertimetheScottishterriersbeganchasingbutterflies,leapingintotheair

AnothertimetheScottishterriersbeganchasingbutterflies,leapingintotheairand

SOCIALBEHAVIOR59

snappingatthemastheyhoveredoverthefield.Andsowecontinuedtocollectalonglistofcaninehabitswhichmakeupadog'srepertoryofbehavior.

Intheend,wehadaninventoryofpatternsofbehavior(Table3.1).By"behaviorpattern"wemeanauniqueandindependentpieceofbehaviorhavingacompleteadaptivefunction.Itmaybeasimplereflexlikethescratchingreflex,oritmaybeapieceofvoluntarybehaviorsuchasinvestigatinganotherdogwiththenose.

Behaviorisageneralandelastictermwhichcanincludealmostanysortofactivityexhibitedbyanentireindividual.Abeliaviorpatternmeanssomethingmoredefinite—anaturalunitofbehaviorwhichhasafunctionbyitself.Onetestforcompletenessoffunctionistoattempttosubdividethebehavior.Forexample,thescratchreflexcanbedividedintoliftingthehindpawanddrawingitdownward.Liftingthehindpawisasubdivisionofbehavior,anditmayhaveanyoneofadozendifferentfunctionsaspartofdifferentpatternsofbehavior.Asweattempttoreducebehaviortoitssimplestparts,weknowthatwearenolongerdealingwithabehaviorpatternwhenspecificfunctiondisappears.

Oncewehaveisolatedsimplepatternsofbehavior,wecanseethattheycanbecombined:eitherinseries,aswhenadoggoesthroughthepatternsofbehaviorleadingtomating,or(morerarely)simultaneously,byperformingtwoactionsatthesametime.Onetestoftheindependenceofabehaviorpatternistoseewhetherornotitcanbecombinedwithothersindifferentsequences.Inhigheranimalslikedogstherearecharacteristicallyanumberofbasicbehaviorpatternswhichcanbecombinedandrecombinedinanumberofways.Weseldomfindlongsequencesofstereotypedbehaviorsuchasarecommonintheloweranimals.

Behavioralsystems.—Anycollectorisfacedwiththeproblemofclassification.Ifhecollectspostagestamps,theyhavetobesortedbycountryandbyyear.Ifitisinsectspecimens,hesortsthemaccordingtotheirresemblancestooneanother,placingallsimilarspecimensinthesamepileandcallingthemaspecies.Behaviorpatternscanbeclassifiedinmanyways,butthemostbasicandimportantmethodisbyfunction—theadaptiveeffectofbehavior.Whenwedothiswefindthatalmostallbehaviorpatternscanbesortedintoninegroups(Scott,1950).TheseareessentiallythesameaswhatKrushinskii(1962)hascalled"generalbiologicalformsofbehavior."

Onebasicfunctionofbehavioristoprovidefortheintakeofnutritivematerialsintothe!>ody.Thisincludesbothsolidsand

60BEHAVIORPATTERNS

liquids.Adogcharacteristicallylapswaterandliquidfoodswithhistongue,standingwiththetaildown.Ontheotherhand,hedealswithsolidfoodbybitingandchewing.Onecharacteristicpatternistolieflat,holdinghisfoodwithhisforepawswhilehetearsoffsmallpieceswithhisteeth.Thepatternsofdrinkingandeatinghaveacommonfunctionandarecalledingestivebehavior.

Averydifferentsortoffunctionisinvolvedinagonisticbehavior,i.e.,adaptationtoasituationofconflictwithanotheranimal.Thedog'sresponsesmayincludethepatternsofbarking,growling,biting,runningaway,orrollingonthebackandyelping.Eachofthesebehaviorpatternshasaspecificfunction,buttheyallhaveacommongeneralfunctionandbearatleastalooserelationshiptoeachother.Takentogether,theyformabehavioralsystem,bywhichwemeanagroupofrelatedbehaviorpatternshavingacommongeneralfunction.

Thesearenotthesameastheorgansystemsofphysiology,althoughtheymayberelatedtothem.Ingestivebehavioriscloselyrelatedtothealimentarysystemwithinthebody,but,aswithallbehavior,itinvolvesthenervoussystemandmuscularsystemaswell.Asystemofbehaviorisnotsomethingwhichcanbedissectedoutofthebody,butratheranattributeofthebodyasawhole.Eachoneincludesagroupofrelatedbehaviorpatternswithunderlyingphysiologicalreactionsinvariousorgansystems.Inshort,thesearefunctionalsystemsatahigherleveloforganization—thatofbehavior.Scientificallyspeaking,thisisthedomainofthetwinsciencesofpsychologyandethology.

domainofthetwinsciencesofpsychologyandethology.

Instinct.—Theseconceptsofthebehavioralpatternandthebehavioralsystemarereplacingtheolderandlessexactideaofinstinct.Peopleusedtosaythatadoghadaninstincttoscratch,ortoherdsheep,ortofight.Aninstinctmightthusrefertoeitherasimplebehaviorpatternoranorganizedgroupofpatternsoreventheunnamedandunknownimpulseswhichcausedananimaltoact.Whileithadconsiderableutilityforearlybiologists,theconceptistooinexacttobeofmuchvalueinmodernscientificworkinthedescriptionofbehavior.Itemploysthesamewordforeitherthepart,thewhole,orthecauseofanorganizedpieceofbehavior.

Inaddition,instinctwasoftenusedasafinalexplanationofbehavior.Atonetime,scientistsclassifiedbehavioraseitherInstinctiveorlearnedandoftenfeltthatifbehaviorcouldbelabeledinstinctivetheyhadexplainedit.Incontrasttothisolderusage,theterms"patternofbehavior"and"behavioralsystem"donotimplyexplanations,butaresimplynamesforwhatweobserve.Explain-

ingtliemisamatterofworkingouttheircauses,andwefindthatitisveryseldomthatanypieceofbehaviorcanbeexplainedonthebasisofonesimplecause.

Therelationshipbetweenbehavioralsystems.—Anyonewhoobservesdogsrunninginthestreetsknowsthateliminativeandsexualbehaviorarerelatedtoeachotherintheseanimals.Malesarehighlystimulatedbysmellingtheurineofareceptivefemale,andamaleabouttomatewithafemalemaygothroughanelaboratepatternofeliminativebehaviorbeforedoingso.Arewedealingherewithonebehavioralsystemorwithtwo?Theansweristhatinotheranimalspecieseliminativebehaviormaybeentirelyunrelatedtosex,asitisinbirds,andhencedefinitelybelongstoaseparatesystem.Evenindogs,mosteliminativebehaviorhaslittletodowithsexualbehavior.Abehavioralsystemisagroupofbehaviorpatternswhichisinmostspeciesunrelatedtoothersystems;however,thepossibilitythatanewrelationshipbetweenbehaviorpatternscanbeformedthroughtheevolutionofbehaviorisalwayspresent.

Anotherexampleofassociatedbehavioralsystemsindogsistherelationshipbetweenagonisticbehaviorandeating,sincedogsfightwiththeirteeth.Allbehaviorsystemsaretosomeextentrelatedtoeachotherbybelongingtoacommonsystem,theindividualorganismwhichdoesthebehaving.

MODIFICATIONOFBEHAVIORALSYSTEMSOFTHEWOLFIN

MODIFICATIONOFBEHAVIORALSYSTEMSOFTHEWOLFINVARIOUSBREEDSOFDOGS

Thenaturalsocialgroupofthewolfisthepack,whichcanbeassmallasasinglepairoraslargeastwenty-fiveorthirtyindividuals.Forthemostpart,thegroupsaresmall,thewolfpackobservedbyMurie(1944)hadsixmembers—fourmalesandtwofemales.Inoneyeartherewasonlyonelitter,butinthenextbothfemaleshadyoung.Thepackhuntedarangeatleastfiftymilesacross,usuallygoingouttogetherintheeveningandreturningthenextmorning.Thecubswereraisedinaden,andtheadultsguardeditandtheimmediatelysurroundingareaasaterritory.

Inourlargeoutdoorfieldsweestablishedartificialpacksofdogs,butsincetheirrangewaslimitedbyfences,theycouldnotshowallthebehaviorofwildwolves.Sometimestheywouldwanderoverthefieldasindividuals,apparentlyinvestigatingeachcornerandtuftofgrass.Atothertimestheymightbeexcitedbyasoundfromoutsidethepenandallrushtowarditasapack.Nostrangedogs

:ZBEHAVIORPATTE=

couldenter,butifastrangepersoncamein,thegroupwouldretreatashortdistanceandrunbackandforth,barkingattheintruder.Inalaterexperiment,Kin^19-54)introducedstrangedogsintosuchagroupandsawconsiderablehostility.Theentirefieldwasevidentlyhometerritorytothepack,itssizebeingpossiblyslightly-smallerthanthehometerritorydefendedbyMurie'swolfpack.Exceptwheretheyareallowedtorunwild,domesticdogsrarelyformstablepacks,althoughdogsinaneighborhoodsometimesjointogetherandrunintemporarygroups.Ahousedogusuallyhasitsclosestsocialrelationshipswithitsowners,sothattheycorrespondtothewolfpack.Thedenareaisthehouse,andthedogsdefendtheyardarounditasaterritoryjustasdowolvesaroundtheden.Mostdogsarewellfedandhavenoneedtohunt,butwillneverthelessmakeregularjourneysawayfromthehouse,markingscentpctheygo.Theirrangeisusuallymuchsmallerthanthatofwolves,oftennotmorethanamileortwoacross,althoughsomedogsmoveovermuchgreaterdistances.

Thusdogsinseneralshowthesamebasiclivinghabitsastheirwildancestors.Wemaynowraisethequestionwhetherselectionanddomesticationhaveimportantlymodifiedbehaviorinthevariousdogbreeds.Toobtaintheanswerwemaycomparethebehaviorofdomesticdo^swiththatofwolves,chieflvasdescribedbvMurie1944)andCrisler1958inAlaska,by'SchenkelU947înthezoologicalgardenofthecityofBaselinSwitzerland,andmorentlybyGinsburg

zoologicalgardenofthecityofBaselinSwitzerland,andmorentlybyGinsburg(1963)intheBrookfieldZooinChicago.Table3.1comparesdogandwolfbehavior,butalsoincludestheiorpatternsoffoxesandcoyoteswhenthesehavebeendescribed.Foxesshowallthebehaviorpatternsofdogsandwolves,atlea^tina^li^htlymodifiedformITembrock,1957\withthecantexceptionofattitudesofdominanceandsubordination.Itwillberecalledthatfoxesdonotruninpacks.Bothfoxe^tesshowanagonisticpatternnotfoundindogsorwolvhtheanimalstandswitharchedbackandloweredhead,likea>pittingcatexceptthatthetailisdown.

behavior.—Thecourtshipandmatingbehaviorofwolvesrbeencb>ervedindetailinthewild,butobservationsoncaptiveanimalsshowessentiallythesamebehaviorpatterns

Littlesexualbehaviortakesplaceexceptduringtheperiod

ptive.Thefirstphvsiologk>festrus

tbleedingfromthevagina,whichmayappeara-earlyas

er.Theentireperiodfromthispointuptothetimewhen

stobereceptivemaybeaslongasforty-fivedays.

TABLE3.1BehavioralSystemsandKnownBehavioralPatternsintheFamilyCanldae

SystemandPattern

(I=Infantileonly)

Dog

Investigativebehavior:

Walkingorrunningwithnosetoground,

sniffing

Headinair,sniffing,mayrunfromsidetoside

Sniffinganaland/orgenitalregion

Sniffinganaland/orgenitalregion

Sniffingnoseorface

Headraised,earserect(listeningandlooking)

Nosingandsniffingurineorfeces

Crawlingforward,movingheadfromsideto

side,sniffing(I)

Epimeleticbehavior:Shelterbuilding:

Turningaroundbeforelyingdown

Diggingbedindirt

Diggingenlargementofden

Grooming:

Scratchingself

Rubbingagainstobject

Rubbingorrollingonground

Bitingownfur

Shakingself

Lickingowngenitaloranalregion

Lickingpuppies,chieflyingenitalandanal

regions(eatingexcreta)

Feeding:

Allowingpuppiestonurse

Vomitingfoodforpuppies

Vomitingfoodforpuppies

Carryingfoodtopuppies

Foodcaching(buryingfood)

Miscellaneous:

Carryingpuppiestonest

Pushingpuppieswithnose

Whining(possiblywarning)

Et-epimeleticbehavior(attentiongettingorcaresoliciting):

Whining

Yelping

Tailwagging(specialkindsalsoseenwith

agonisticbehavior)

Lickingfaceorhandsofperson,usuallywith

tailwagging

Touchingwithpaws_

Allelomimeticbehavior(oftencombinedwithet-epimeletic,investigative,andagonisticbehavior):

Walkingorrunningtogether

Sittingorlyingdowntogether

Gettinguptogether

Sleepingtogether

Howlinginunison

Howling,solitary(loneliness)

F,NF

F,NF,N

F,N

F,N

N

F,N

F

F,NF

E

F,N

F

F,N

N

F,N

N

N

NNN

F,NN

F,N

F,N

N

F,N

F,NF,NF,NN

N

Wolf

Coyote

Fox

M

Y,S

M,S

M

Y,S

M?

MM

M,Y

Y

M,YM,C

YYY

M

S

M.Y.S

M

S,CM

MMMM

M,Y,S,CM,Y

M

M

ivr

F=Field;N=Nursery;K=Kennel;E=Elsewhere(whereobservedindogs)

M=Murie;Y=Young;S=Schenkel;C-Crisler;T=Tembrock(wherereportedinothercanid?)?=Behaviorimplied,notdirectlydescribed..

•Characteristicallydifferentfromwolvesordogs—higherpitched,interspersedwithbarking.

C4

BEHAVIORPATTERNS

TABLE3.1—Continued

SystemandPattern(1=Infantileonly)

Dog

Woif

Agonisticbehavior(patternsassociatedwithconflict):Fightingandpredation:

ChasingF

BitingF

SnappingteethK

Pawing(sometimesinstandingposition)....N

Snarling(showingteeth)F,X

F,NF,NK

Growling

Barking

Waggingtipoftail

Tailswitching

Playfulfighting,similartoabove,butlessintense,includespanting

Pouncingorspringing

Tossingsmallgameintoair

Herding

Defenseandescapereactions:

Sitting

Crouching

Runningaway

Yelpingandshowingteeth

Tailbetweenlegs

Rollingonback,pawingandextendinglegs..Attitudesofdominance:

Forepawsonback,growling,tailerect(maybiteneck)

Standingoverdogonground,growling

Standingorwalkingstiff-leggedwithtailerect

Headdown,backarched,taildown

Mounting,taildown,neckbiting,without

pelvicthrusts

Attitudesofsubordination:

Allowingdominantanimaltoplacefeetonback,tailerect

Taildown

Tailbetweenlegs,crouching,earsdepressed..

Rollonback,legsextended,tailbetweenlegs

Miscellaneous:hairraising

Sexualbehavior:Male:

Runningwith?.

Forepawsextended,bodythrownbackonhaunches,headtooneside

Licking9genitalia

Mounting

Clasping

Pelvicthrusts

Copulatorytie...

Female:

Runningwithcf

Forepawsextended,bodythrownbackonhaunches,headtooneside

F.N

N

F,XF,XXF,N

F,X

X

X

X

M,VM.Y.Y,S

M,Y,M,Y.M.YS

s

M.SM

M

Y.C

YMMS

v.s

M

S

M-.S

M.-S

C

sy?

Y?

Y

If?,C

Coyote

MM

Fox

M

M

T(follow)

F=Field;N-Nursery;K-Kennel;E=Elsewhere(whereobservedin

M-Murie;V=Young;S-Schenkel;C-Crisler;T-Tembrock(wherereportedinothercanids)■implied,notdirectlydescribed.

differentfromwolvesordogs—higherpitched,interspersedwithbarking.Notedifferencesfromwolvesanddogsindominance-subordinationbehavioroffoxesandcoyotes.Informationincomplete.

SOCIALBEHAVIOR


SystemandPattern(I=Infantileonly)

Mounting

Clasping

Pelvicthrusts

Standingford"

Tailmovedtooneside

Both:

Both:

"Wrestling."forepawsaroundeachother's

necks

Lliminativebehavior(seecloselyrelatedpatternsofinvestigativebehavior):Male:

Micturitionwithall4legsextended(I)

Micturitionwithliftingofhindleg,usually

inplacesusedbyotherd"'s

Female:micturitioninsquattingposition

Bothsexes:Wandering,nosinggroundbeforedefecation

Defecation

Scratchinggroundwithall4feetfollowing

defecation(rarein9)

Defecationandurinationinplacespreviously

used

Ingestivebehavior:

Lapping,tailoutanddown

Chewingandswallowing,sametailposition..

Gnawing,holdingfoodwithpaws

Eatinggrass

Sucking,pushingwithhead,alternatelypushingwithforepaws,hindfeetpushing,tail

outanddown(I)

outanddown(I)

Comfort-seekingbehavior(shelter-seeking):

Lyinginaheap(I)

Lyingclosetogether

Curlingup

Miscellaneousmotoractivities:

Twitchingwhileasleep(I)

Stretching

Yawning

Rollingover

Dog

N

N

N

F,N

F

KF,N

F,N

F,N

K,N

F,N

F,NNKF

F,NNKF

N

NFF,N

NF,N

F,NF,N

Wolf

Y,S

Y

Y

Y,SS

M

M

M,C

M

Coyote

M

Fox

F=Field;N=Nursery;K■=Kennel;E=Elsewhere(whereobservedindogs)

M=Murie;Y—Young;S=Schenkel;C■=Crisler;T=Tembrock(wherereportedinothercanids)

?=Behaviorimplied,notdirectlydescribed.

*Characteristicallydifferentfromwolvesordogs—higherpitched,interspersed

*Characteristicallydifferentfromwolvesordogs—higherpitched,interspersedwithbarking.

orroughlysixweeks(YoungandGoldman,1944).AcaptivewolfdescribedbyMurie(1944)hadacyclethreeweekslong,beingreceptiveonlyinthethirdweek.MostcubsareborninMay,whichmeansthatactualmatingbehaviorusuallytakesplacetwomonthspreviously,inFebruaryorMarch.

Thepatternsofsexualbehaviorassociatedwithcopulationarerelativelysimple,beginningwithmutualinvestigationofthegenitalandanalregions.Thefemalesoonstandsstill,holdinghertailtooneside,andhervaginamaymoveslightlywhentouched.The

66BEHAVIORPATTERNS

malemountsthefemalefromtherearandattemptstoinserthispeniswhileclaspingthefemalewithhisforepaws.Rapidpelvicthrustsfollowinsertion,andstimulationofthebaseofthepeniscausesrapidenlargementofthisregion(thebulbusglandis)throughengorgementwithblood,sothatthetwoanimalsbecomelockedtogether.Themalethenturnsaroundsothatthetwomaystandtailtotailforsomeminuteswhileejaculationgoeson.Allthisbehaviorisessentiallythesameasinthedog.

Beforethefemalebecomesreceptivetheremaybeconsiderablecourtshipbehavior.Atypicalpatterninvolvesextendingthefore-pawsonthegroundwhilekeepingtherearlegssemi-erectandthrowingtheheadtoonesidewiththetongueout.Bothanimalsmayexhibitthispatternofbehavior,thenonedartstooneside,andtheotherfollows.Anassociatedpatternconsistsofthrowingtheforelegsaroundeachother'snecksinasortofplayfulwrestling.AccordingtoCrisler(1958),thesepatternsofbehaviorareverysimilarinwolvesanddogs,exceptthatthewolvesappearmoreseriousanddignified.

Thesexualbehaviorpatternsofwolvesanddogsarerelativelysimple,andtheyarenotlinkedinsequencesbyanystrongdegreeofgeneticorganization.Courtshipbehaviorisnotnecessaryforcopulation,foramalemeetingareceptivefemalewilloftenmatewithverylittlepreliminarybehavior.Thiscontrastswiththebehaviorofsomespeciesofbirdsinwhichelaboratecourtshipisnecessaryinordertosynchronizethelaterparentalcarebythetwosexes.However,thephysiologicalchangeswhichproducesexualreceptivityinthefemalearesuchastoproduce,undernaturalconditions,alongcontinuedassociationbetweenapair.Theodoroussubstancewhichstimulatesthemaleis

associationbetweenapair.Theodoroussubstancewhichstimulatesthemaleisproducedlongbeforethefemaleisreceptive,sothatthemalestaysincloseattendance.Thegeneralcourseofmatingbeginswithaperiodinwhichthefemaleisattractivebutasyetrepulsesthemale.Sheisapparentlyalsoattractedtohiminthisstage,sinceshewillsometimesinitiatecourtshipbehavior,butsherejectsthemalewhenheattemptstomount.Shefinallybecomesreceptiveforaperiodofdaysorweeks,sothatsexualbehaviorcanberepeatedoverandoveragain.Thislonjâssociationandconstantinteractionwouldbeexpectedtoproduceastrongattachmentbetweenthepair.

Whetherwildwolvesarcmonogamousisstillamatterofcon-jecture.Certainlydogsarcnot,underthehighlyartificialconditionsinwhichtheyliveandarcusuallybred.Atanyrate,thereisnothinglikethesituationinaflockofbighornsheeporherdofelk,inwhich

SOCIALBEHAVIOR67

femalescomeintoheatforonlyadayorsoandasinglemalenormallymateswithalargenumberoffemales.Inthewolfpack,allthefemalesarereceptiveforlongperiods.Thereisconsiderableevidencethateachmaleisquitepossessiveofonefemaleandmaymateonlywithher.Ginsburg(1963)findsthatalthoughwrolvesincaptivityarepolygamous,consortshipsmaybeformedbyeithermember'sabilitytokeepothersawayfromitsmate.

Wolfanddogpatternsofsexualbehaviorarethusquitesimilar.Theprincipalmodificationproducedbyselectionisintheseasonalnatureofthesexualcvcle.Innearlyalldogbreeds,thefemalescomeintoheatatapproximatelysix-monthperiodsduringanyseasonoftheyear.Furthermore,thefemalesusuallymatureinthelatterpartofthefirstyear,whereaswolvesdonotcomeintoestrusuntilthesecondoreventhethirdyear.Therehasobviouslybeenselectiontowardearlymaturityandincreasedfecundityindomesticdogs.Thistraitmayalsobeassociatedwithselectionforsmallersize,asrapidgrowthusuallyceaseswithsexualmaturity.

Onebreedofdog,theAfricanbasenji,stillshowsaseasonalcycleofsexualbehavior.IntheseanimalsthemajorityoffemalesrearedinthelatitudesofEnglandandtheUnitedStatescomeintoheatinSeptemberandproducepuppiesinDecember.TheAustraliandingo,whicliisusuallyassumedtobeadomesticdogthatwentwild,showssimilarseasonalbreedinginnorthernlatitudes,butinitsnativeSouthernHemisphereitbreedsinthecorrespondingautumnseason,which,ofcourse,isMarchinAustralia.Thebreedingperiodsofboththebasenji

which,ofcourse,isMarchinAustralia.Thebreedingperiodsofboththebasenjiandthedingoareobviouslycontrolledbychangesinseasonalconditions,andFuller(1956b)hasshownexperimentallythatartificiallyshorteningthelengthofdayinthespringwillproduceheatperiodsinthebasenjiasearlyasJuly.

Itispossiblethattheseanimalsaredescendedfromveryearlydogbreedswhichoriginatedbeforetheseasonalhabitwaslost,andthatthetimeofbreedingwasmodifiedbyselectiontocorrespondtotropicalconditions.Thebreedingcycleofbasenjisattheequatorisasyetunknown.Herethelengthofdayisconstant,butthereareseasonalrisesintemperatureattheequinoxes.

Theunderlyingphysiologicalbasisforthesexualcycleoffemaledomesticdogsconsistsofbalancedreactionsbetweenthehormonesofthepituitaryglandinthebrainandthehormonesoftheovary,orfemalesexgland.Hormonesofthepituitarystimulatetheovariestoproduceandexpeleggs.Atthescarleftbyeachegg,amassofcells(thecorpusluteum)continuestogrowandproducesprogesterone,ahormonewhicliactschiefivontheuterustomaintainpregnancy,

BEHAVIORPATTERNS

butalsosuppressesthehormonesofthepituitary.Thecorpusluteumcontinuestofunctionforaboutfourmonths,afterwhichitgraduallydisappears,permittingthepituitaryhormonestoactagaintostartanewcvcle.Inwolves,basenjis,anddingos,thepituitarymustbestimulatedbvchangesinthelightcyclebeforeitwillact,evenwhenprogesteroneisabsent.

Tosummarize,sexualbehaviorindogshasbeenchieflymodifiedawayfromseasonalbreedingandtowardearlysexualmaturity,bothchangesresultinginincreasedfecundity.Whiledomesticdogsrarelyhaveanopportunitytoexhibitallthepossiblepatternsofsexualbehaviorundertheusualconditionsinwhichtheyaremated,thebasicpatternsofbehaviorarethesame,withnoobviousdifferencebetweenvariousbreeds.

EHminativebehavior.—Asthevtravelovertheirhuntingrange,malewolvesregularlyvisitcertain"scentposts,"whichmaybesmallstonesorbushesaswellasactualpostsortrees.Heretheyliftthelegtourinateorsquattodefecate,andscratchthegroundthereafter.Similarbehaviorisfamiliartotheownerofanydomesticdog.However,weweresurprisedtofindthatdogskeptinourlargerunsandfieldswithboardfencesshowedeliminativebehaviorquiterarelycomparedtohousedogs,whichseemtospendmostoftheirtimegoingfrombushtobush.Inthemalethetvpicalpatternofmicturitionistoapproachascent

bushtobush.Inthemalethetvpicalpatternofmicturitionistoapproachascentpost,smellthiscarefully,thenliftonehindlegandspravasmallquantityofurineontheobject.Dogsconfinedinapenorfieldthatisnotenteredbyotheranimalsrarelydothis,andmalesraisedinsuchanenvironmentmaycontinuetoshowthepuppypatternofsquattingurinationwellintomaturity.Theprimarystimulusorreleaser'fortheleg-raisingpatternisapparentlytheodorofastrangedog'surineincombinationwithavisuallandmark.Dogsinastrangelocalitywhichotherdogshavenotpreviouslyvisited,willapproachandurinateonanyobjectswhichareslightlyelevated,suchasstones,bushes,andtreetrunks.Onceliehasurinatedonanobject,thedogisinhibitedbythesmellofhisownurinefromdoingsoagainuntilanotherdoghasusedthesite(vonUexkiillandSards,1931).

Thepatternofbehaviorassociatedwithdefecationisdifferentandmuchlessfrequent.Themalesquatstodefecatenearascentpostandmayfollowthisbyscratchingthegroundcloseby.Thisscratchingneverhasth<ofcoveringthefeces,asitdoesin

cats,andifithasanyfunction,itisprobablytoaddanothervisualmarktothesite.

Scentalsonportant.All*>thmaleandfemale,have

SOCIALBEHAVIOR69

apairofglandsjustinsidetheanus.Itispossiblethattheseimpartacharacteristicodortothefeces.ThisisinadditiontothescentglanddescribedbySeton(1925)onthedorsalsideofthebaseofthetail.Atanyrate,dogscharacteristicallysnifffreshfeces,andpartoftheinvestigatorybehaviorbetweendogsisamutualsniffingofthetailregion.

Theeliminativebehavioroffemalesisquitedifferentfromthatofmales.Inhousedogs,afemalewillvisitscentposts,butonlynearherownhome,andusuallyinonlyoneplace.Shecharacteristicallyurinatesinasquattingposture,butsomefemalesalsolifttheirlegs.Thefemaleusesmuchthesamedefecationpostureasthemale,butrarelyifeverscratchesafterward.

Intheperiodofsexualreceptivity,thebehaviorofthefemalechanges.Shenowwandersmorewidelythanusual,visitingseveralscentpostsandurinatingoneach.Whenmalessubsequentlyvisitthesepoststheybecomehighlyexcited,pursuethefemale,andremaininthevicinity.Thehouseholderwhoownsa

pursuethefemale,andremaininthevicinity.Thehouseholderwhoownsafemalemayexpecttofindhalfadozenmalesregularlycampedonhisdoorstepassoonasthefemalecomesintoheat.Apparentlyallthemaleswithinmilesbecomeawareofthefactwithinashorttime.

Wehadexpectedtohavetroubleofthissortwithourdogcolonyandweresurprisedtofindthateventhoughseveralfemalesmightbeinheatinsideourpens,weneverhadmorethancasualvisitsfrommalehousedogsintheneighborhood,andthattheymadenoattempttostaynearby.Thissuggeststhatthemaleshavetocomeintoclosecontactwiththeurineofafemaleinordertobesexuallystimulated,andthatthescentisnotcarriedontheairforanydistance.Onceinclosecontact,malescanreadilydistinguishonetypeofurinefromanother.BeachandGilmore(1949)placedtwosamplesoffemaleurineinanexperimentalroomandallowedonemaletoenteratatime.Everymalespentmoretimeexaminingthatofafemaleinestrusthantheurinefromanotherfemale.

Theprincipalsocialfunctionofeliminativebehaviorindogsisthereforetobringareceptivefemaletogetherwithamale.Ithasneverbeenexperimentallystudiedinwolves,buteliminationcertainlydoesnotfunctionasterritorialmarkinginanystrictsense,sincewolvesmakenoattempttodefendanythingbuttheareaclosetotheirdens.Nordoesitseemtohaveanyterritorialsignificanceindomesticdogs.Aslongastheresidentmaleisawayfromhome,strangemaleswillfreelyentertheyardandmarkit;themalereturningtothesceneshowsnosignsoflookingforanintruder.Asidefrombreeding,thebehaviorseemstofunctionsimplytokeep

animalsawarethatothersexistandindicatewheretheycanbefound.Forwolveslivinginpacksthereisordinarilynoreasonforonestrangewolftotrytofindanother,andthesescentpostsareprobablyusefulonlytoyounganimalsnotattachedtoapack.Suchsignswouldhelpthemeithertofindapackorformanewonewithsimilarisolatedindividuals.

Thisissomewhatconjectural,becausethebehaviorhasneverbeenfullyobservedinwildwolvesnorhastheirmatingbehaviorbeenadequatelystudied.Whathappens,forinstance,whenafemaleinapackcontainingseveralmalescomesintoheat?Observersoftenassertthatafemalemateswithonlyonemale,butouronlydirectevidencecomesfromobservationsoncaptiveanimals.Inanycase,undertheconditionsofawildpackwewouldexpectthatthefemalewoulddepositherurineonlycloseenoughtoattractthemalesinherowngroup.

Anotherpeculiarityofeliminativebehaviorindogsandwolvesisthattheyneversoiltheirsleepingplaces.Thisis,ofcourse,highlyadaptiveforanimalswhichliveindens,andthedevelopmentofthistraitinyounganimalswillbediscussedinalaterchapter.

Thepatternsofeliminativebehaviorhavebeenevenlessmodifiedbyselectionthanthoseofsexualbehavior.Althoughsomeminorpeculiaritiesmayexist,therearenowidespreaddifferencesbetweenthebreeds.

Epimeleticbehavior.—Thisisthegivingofcareandattention.Indogssuchbehaviorisprincipallydirectedtowardyoungpuppies,withsomeself-care.Thereisalmostnoepimeleticbehaviorbetweenoneadultandanother.

Thetypicalbehaviorofafemaletowardheryoungpuppiesaftershehasbeenawayistowalktowardthem,nosethem,andliedownonhersidewithherfeettowardthem.Thenshebeginsnosingandlickingeachpuppy,whichstimulatesurinationanddefecation.Theresultsarecleanedupbythemother'stongue,thuskeepingthenestclean.Inthemeantime,arousedbythetactilestimulation,thepuppiesworktheirwaytowardthemotherandattempttonurse.Inthis,themotheriscompletelypassive,notattemptingtoplacethepupsinanyparticularposition.However,ifapuppygetsawayfromtheothersandbeginstowhineoryelp,themotherwillusuallygotoit,pickitupcarefullywithherjawsandcarryitbacktotherest.Thepuppyisalwayscarriedwithitswholebodyinhermouth,feetdanglingdown,ratherthanbytheskinascatscarrytheirvoung.

Thisbehaviorisstronglyinfluencedbythematernalhormone

prolactin,whichalsostimulatestheflowofmilk.Oneyoungbasenjimotherhadherfirstpuppiesanddroppedtheminvariousplacesalloverthenurseryroom.Shewashighlyexcitedbutpaidnofurtherattentiontothemevenwhenwebroughtthemalltogetherinthenestboxandtriedtogethertoliedownbesidethem.Finallywegaveheraninjectionofprolactin.Withinanhourshehadsettleddownwiththepuppies,andpeacereigned.

Asthepuppiesgrowolderthesepatternsofbehaviorbegintofadeandotherstaketheirplace.Whenthepuppiesareaboutthreeweeksofage,themotherbeginsvomitingfoodforthem.Manymotherswilleatthisthemselvesifthepuppiesdonotfinishitall.Themotherallowsthepuppiestonurselessoften,andtheysometimesdothiswhilesheisstanding.Themothersstillcleanthepuppiesiftheysoilthemselves,althoughbythistimethepuppiesurinateand

puppiesiftheysoilthemselves,althoughbythistimethepuppiesurinateanddefecatebythemselvesoutsidethenestbox.

Inthedomesticdog,malesrarelyshowanyinterestinpuppies,butinwolvesmalesaswellasfemalesvomitfoodforthecubs.LoisCrisler(1958),whoraisedandobservedtwosetsofcapturedwolfcubsinAlaska,reportedthatheryearlingmaleandfemalebothfedtheyoungercubs,eventhoughsexuallyimmaturethemselves.Wecanconcludethatthepatternsofcare-givingbehaviorexhibitedtowardolderpuppiesarecommontobothsexesandarenotproducedbyhormones.

Theprincipaldifferencesbetweendogsandwolvesinthesepatternsofbehaviorarethattheyarelesswelldevelopedindogs.Humanownershavelargelytakenoverthecareofolderpuppies,whichmeansthatthepatternofvomitingcanbeweakenedwithoutseriousconsequences.Itseemstohavebeenmuchreducedinmales,althoughthismaysimplybebecausemaledomesticdogsarerarelygiventheopportunitytodeveloprelationshipswithyoungpuppies.However,inourlimitedobservationsofpuppiesrearedinlargefieldsbybothparents,weneversawthemalecaringfortheyoung.

Anothersetofpatternsofepimeleticbehaviorisconcernedwithself-grooming.Dogswilllickthemselvesintheanalandgenitalregionsandwillalsolickwounds.Theyscratchareaswhichareirritatedorattempttobitethemwiththeirteeth.However,thereisnoelaboratecleaningandgroomingsuchasoneseesincatsandmice.Groominganotheradultanimalisveryrare,althoughonedogwilllickanopenwoundonanother'sbody.Thesepatternsofbehaviorareessentiallythesameindogsandwolves,withnoobviousspeciesorbreeddifferences.

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Et-epimeleticbehavior.—Theepimeleticbehaviorofthemothersisassociatedwiththeet-epimeleticbehaviorofpuppies—callingforcareandattention.Forthemostpart,thisconsistsofdistresscallsbyyoungpuppies,thatis,whinesandyelpsofdifferentdegreesofloudness.Similarnoisesaremadebyyoungwolfcubs,althoughpossiblynotsoreadily.

Asthepuppiesgrowolder,theywillruntothereturningmother,waggingtheirtailsrapidlyandleapinguptopawandlickherfaceandbreast.Themotherfrequentlyvomitsfoodforthemontheseoccasions,andthepatternofbehaviorofthepuppiesprobablyhasthefunctionoffoodbegging.Thisisthesamesort

ofthepuppiesprobablyhasthefunctionoffoodbegging.Thisisthesamesortofbehaviorwhichpuppiesexhibittowardtheirhumanmasters,andtheremaybesometendencytoprolongitintoadultlifeincertainbreedswhichareuncommonly"playful"asadults.This,however,isjustanimpressionandstilllacksanyobjectiveproof.

Ingesiivebehavior.—Thepatternsofbehaviorassociatedwithtakinginsolidfoodandliquidsarequitesimilarindogsandwolves.Liquidsareingestedbylapping.Thedogorwolfstandswithhistaildownandscoopsupwaterorliquidfoodwithhistongue,makingconsiderablenoiseintheprocess.Semi-solidfoodsaremanagedinasomewhatsimilarway,thedogseizingpartofthefoodinhisteeth,releasingitandloweringhisheadsuddenlytoshiftthefoodintothebackofhismouth,andgulpingitquickly.Hedealswithbonesortoughpiecesofmeatbylyingdown,holdingthefoodinhispaws,andeithertearingoffstripswithhisfrontteethorgnawingontheobjectwithhisheavybackteeth.

Anotherpatterniscarryingfoodinthejaws,theanimaltrottingalongwithheadheldhighandrollinghiseyesineitherdirection.Wolves,withtheirstrongerjawsandneckmuscles,areabletoaccomplishprodigiousfeatsinthisway.Awolfwillpickupapieceofboneandmeatweighingtwentypoundsormoreandcarryitwithlittleeffort.Anothercommonhabitofwolvesistoburyfoodaroundtheden.Inacoldclimate,thispreservesthemeatfrombirdsandothercarrioneaters,butinwarmweatherthefoodspoilsrapidly.Thistraitpersistsinmosthousedogs,whichburyfoodaroundtheyardsoftheirowners.Inourlaboratory,somedogspersistentlyusedtheirnosestoburytheirfooddisheswithshavingsfromthefloor.

Beingfairlysimple,thesebehaviorpatternscanbeusedwithmanydifferentkindsoffood,andmaybecombinedandmodifiedinvariousways.Physiologicallythedogisprimarilyadaptedforameatdietandahuntingexistence.AccordingtoMcCay(1946),dogsunderordinaryconditionscangoforatleastaweekwithoutfoodor

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waterandsuffernoseriousharm.Whenfoodisavailable,theyeatrapidly,makinglittleefforttochewtheirfood.Theyhavealargegulletwhichpermitsthemnotonlytoeatbigchunksbuttovomititbackeasilyforthebenefitofpuppies.Theingestivebehaviorofdogsandwolvesissoorganizedthattheanimaleatsagreatdealwhenfoodisavailable,butisabletogoforlongperiodswithoutit.Consequently,theideaofa"hungerdrive"measuredbytheamount

withoutit.Consequently,theideaofa"hungerdrive"measuredbytheamountofhourssinceeatingdoesnotapplytothedog.Thedogis,inasense,alwayshungry,butheisnotdriventoeat.Oneofourinvestigatorsgaveadoganelectricshockwhenitcamenearitsfooddishandthenwaitedtoseehowlongitwouldtakebeforethedogcamebacktoeat.Thedognevercameback.Afterwaitingseveraldaysforthedogtoeat,theexperimenterstoppedtheexperimentsforfearofharmingtheanimal.Thisagreeswithtrappers'reportsofwolfbehavior.Ifawolfgetsintoatrapandescapes,itishopelesstousethistypeoftrapagain,asthewolfalwaysavoidsit.

Wefoundthatoneofthebestwaystousefoodmotivationinanexperimentalsituationwastogiveapuppyatasteofsomespecialfoodeachday(weusedsardines).Bythethirdday,thepuppywashighlymotivated.ElliotandKing(1960)foundthat,whentheyfedpuppiesatregularmealtimes,theanimalsateeagerly,evenwhensogrosslyoverfedthattheycouldnothavebeenphysiologicallyhungry.The"habitofeating,"orfoodreinforcement,isthusaveryeffectivemotivatingforce,evenintheabsenceofphysiologicalhunger.Thiscontrastswiththesituationinotheranimalslikeratsorsheep,whichnormallyeatcontinuouslyforlongperiods.Inthesespecies,ahighstateofmotivationcanbeproducedsimplybykeepingthemfromfoodforafewhours.

Therearefewbreeddifferencesinthesebasicpatternsofbehavior,andmostofthemareconnectedwithfoodchoice.Beforescientificinformationconcerningnutritionwasavailable,dogownersfedtheirchargesalmostanything—porridge,crustsofbread,orperhapsnothingbutbones.Theremusthavebeenselectionforanimalswhichwerenotfussyaboutfood,andmanyoftoday'shuntingandworkingbreedswilleatandthriveonfoodwhichotherswillreject.Forexample,wefoundnodifficultyingettingyoungpuppiestostarteatingordinarydogfood,exceptbasenjis,althoughthebasenjisreadilyaterawmeat.

Shelter-seekingbehavior.—Thisisnothighlydevelopedinwolves.Wolfdensareusuallyformedbyenlargementofnaturalcavesorofholesstartedbyburrowinganimals.Thewolfdoesalittlediggingtomaketheareacomfortablebutmakesnoefforttobuildanest.In

coldweather,wolvessleepinacurledpositionwiththeirnosesburiedinthelonghairoftheirtails,andtheywillalsosleepneareachotherforwarmth.However,theirmechanismsformaintainingheataremuchbetterthanindogs,andwolveshavebeenseenasleeponthesnowwithlegsoutstretched(AllenandMech,1963;Gins-burg,1963).

InourlargeoutdoorrunsattheJacksonLaboratoryweconstructedartificialdens(seeFig.1.3).Littersraisedtogetherwouldsleeptogetherintheseenclosuresandstayinsidewhentheweatherwasbad.Awell-knownpatternofbehaviorconnectedwithsleepingisthetendencyofdogstoturnaroundseveraltimesbeforelyingdown.Thisprobablyhastheadaptivefunctionoffeelingwiththepawsforasmoothareaonwhichtorest.

Thesefundamentalpatternsofbehaviorarenotgreatlymodifiedinthedifferentdogbreeds.Perhapsthemostnoticeablevariationisinthemodificationofsleepingattitudesincertainbreeds.Manydogswillsimplylieontheirsideswithfeetoutstretched,butsomewilllieontheirbellieswithforeandhindfeetextended,orsometimesevenlieontheirbacks.Theseposturesprobablyrepresentadjustmentstoanatomicalpeculiaritiessuchaslegstructureordistributionofbodyhair.

Allelomimeticbehavior.—Thisbehaviorisdefinedasdoingwhattheotheranimalsinagroupdo,withsomedegreeofmutualstimulation.Puppiesfirstdothisataboutfiveweeksofage,whenthelitterbeginstoruninagroup.Thisforeshadowsrunninginapack,oneoftheoutstandingcharacteristicsofdogandwolfbehavior.Todoso,theanimalsmustmaintaincontactwitheachother,primarilythroughvision,butalsothroughhearingandtouch.

Aswellasrunning,dogsandwolvesarefoundlyingdowntogether,gettinguptogether,andevenbarkingandhowlinginunison.Allelomimeticbehaviorisalsoimportantinpredationwhenapackmakesacombinedattackonalargeanimal.

Wehadexpectedtofindmoreofthisbehaviorinbreedswhichhuntinpacks(as,forexample,beaglesandfoxhounds)thaninbreedswhichhuntinamoresolitaryfashion.However,itturnedoutthattheprincipalmodificationofbehaviorinhoundsisnotapositiveincreaseofallelomimeticbehaviorbutsimplyalesseningofagonisticbehavior,sothatstrangeanimalscanruntogetherinthesamepackwithoutfighting.

Allelomimeticbehavioristhusabasicpartofthesociallifeofdogsandwolves.Ifananimalkeepsinconstantcontactwithothersofitskind,behaviorofthissortwillinevitablyresult.Thetendencyto

staywithothersisespeciallystronginyounganimals.Adultwolvesanddogswilloccasionallygooffonsolitaryhuntingexpeditions,aswhenapackwillsplit

willoccasionallygooffonsolitaryhuntingexpeditions,aswhenapackwillsplituptofindgame.Eventhen,theyusuallymaintainvocalcontact,sothatifoneanimalissuccessful,theotherssoonfindit.Allelomimeticbehaviorisusefulinhunting,sinceagroupisabletoattacklargeanimalsmoresuccessfullythanisanindividual,butitsprimaryfunctionistoprovidesafety.Aslongasthemembersofagroupkeepinconstantcontact,theycanreacttogetherinemergencies.Whensomethingthreatenstheden,thewholepackdefendsit.

Agonisticbehavior.—Sincewolvesareprimarilycarnivorousanimals,alargepartoftheirbehaviorisconcernedwithpredation.Gettingfoodinvolvesthreesystemsofbehavior:investigatorybehaviorinfindinggame,agonisticbehaviorinattackingit,andin-gestivebehaviorineatingit.Undernaturalconditions,wolvesarethechiefpredatorsoflargehoofedanimals:deer,moose,mountainsheep,orcaribou.Thesefoodpreferencesareeasilytransferredtodomesticstock,andwolvescanbehighlydestructivetodomesticcattleandsheep.Murie(1944)hasdescribedhowwolveshuntmountainsheepinAlaska,andLoisCrisler(1956)theirhuntingofcaribou.Adultanimalsingoodconditioncaneasilyescapefromwolves,whicharerelativelyslowrunners.Thebestopportunityforthewolfistofindayoungorlameanimalawayfromtherest.Inattackingalargeanimal,awolfavoidstheheadandmakesquickdashesatthehindlegs,springingbackifunsuccessful.Ifananimaliscornered,severalwolvesmayjointogetherintheattack.Usuallythepreycannotsuccessfullyavoidallofthem.

Theexactmethodofhuntingdependsuponthepackanditsusualprey.AllenandMech(1963;Mech,1962and1963)watchedapackofwolvesforseveralyearsasithuntedmooseonIsleRoyaleinLakeSuperior.Thispackwasunusuallylarge,containing15or16members,andalwaysattackedinagroup.Inanattackthewolveswoulddartinandback,avoidingthehoovesofthemoose,thenswarminginforamassassaultiftheanimalattemptedtorun,clingingtoitsrumpandflanksandeventuallyitsnose.Onlyoneoutofeverythirteenmooseapproachedwaskilled,asthepacksoonleftanyanimalwhichfoughtbackvigorously.Outof68kills,20werecalves,andonlyoneoftheremainingadultswasundersixyearsofage.

Wolvessometimesappeartoherdtheirprey.Sincethewolvesoftenseparate,ahuntedanimalmayunwittinglycomeclosetoonewolfwhileavoidinganother.Thispatternofpursuingherdanimalsisusedinthedomesticherdingdogs,butthesheeporstockdogis

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76BEHAVIORPATTERNS

notallowedtoactuallyattack.Theherddogmustbeaggressiveenoughtochasesheepbuttimidenoughtobeinhibitedfromattackingthembyadistantshoutorgesturefromtheherder.

Wolves,ofcourse,donotalwayshavelargegameavailableandeatavarietyofotherfoodsincludingberriesandcarrion.Theyoccasionallyshowaspecialpatternofbehaviorforhuntingmeadowmice,inwhichtheyleaponthemousewithallfourfeet,pinningittotheground.ThispatternisseeninmanywildCanidae,suchascoyotesandfoxes,butisrarelyseenindomesticdogs,whichusuallypouncewithoutleapingofftheground,asdowolvesonmostoccasions(Murie,1944).

Thepatternsofagonisticbehaviordirectedagainstotherwolvesaresomewhatdifferentfromthoseusedagainstprey,possiblybecauseofthedifferentsize,shape,andbehaviorofwolvesascomparedtothepreyanimals.Forexample,twofightingwolveswillshowmuchin-and-outfighting,slammingtheadversarywiththehips,andthendivingforhislegs(Ginsburg,1963);buttwodogsmaycometogetherheadtohead,eachattemptingtogetpastthesnappingjawsoftheotherandslashingatthenearestavailablepart,usuallytheneckorshoulder.Ifoneanimalgetsagoodholdontheother'sneck,hewillusuallyhangonastheotheranimalcannotbitehiminthisposition.Meanwhileeachtriestoforcetheothertotheground.Muchlearningandadaptationareinvolvedinfighting,butthebasicpatternsofbehaviorareessentiallythesameindogsandwolves.

Thereareseveralcommonsituationswhicharouseagonisticbehaviorinwolvesanddogs.Oneoftheseisthepossessionoffood.Ananimalfeedingonabonewillgrowlatanyotherwhichcomesnear,andwillsometimesmakeashortrushandsnap,whichtheintrudereasilyavoids.Wehaveseenthispatternbeginninginyoungpuppiesasearlvastwoorthreeweeksofage,whenaridiculouslysmallpuppywillgrowloverafreshbone.

Anothersetofbehaviorpatternsisassociatedwiththeintrusionofstrangersintotheterritorvneartheden.Thefirstreactionisbarking,whichseemstobeprimarilyawarningsignal.Thewholepackjoinsin,andthecontinuousnoisemayinitselfhaveanaversiveeffect.Iftheintruderkeepsadvancing,thedefendingwolfpackwillusuallyfirstinvestigatehimandthenattack.Theintruderruns,tailbetweenhislegs,andtheothersrushafter,bitingathisflanks.

IItwostrangeanimalsapproacheachotheronneutralterritory,

hwalksslowlyandstiff-leggedlytowardtheother,tailheld

straightupandwavingslightlyfromsidetoside.Theytouchnoses

andthenmaycautiouslynoseeachother'stailandgenitalregion.Suchbehaviormayleadtomutualacceptancebutmoreoftenresultsinanattackbyoneanimalortheother.

Withinanaturalsocialgroup,agonisticbehaviorisreducedtoarelationshipofdominanceandsubordination.Thismaytakeseveralforms,dependingonthedegreeofdominance.Somedogssimplygrowlateachotherandmoveapart.Moretypically,thedominantdogplaceshisfeetonthebackoftheother,growlingashedoesso,whilethesubordinateonekeepshisheadandtaillowered.Astillmoresubordinateanimalmayrolloveronhisbackwhilethedominantonestandsoverhim,headtohead;thesubordinateanimalrapidlysnapshisteethandyelps.Sometimesthedominantanimalmakesafewthreateningsnapsatthesubordinateone.WolvesintheBrookfieldZoo(Ginsburg,1963)showapatternofbehaviornotcommonlyseenindogs,wherethedominantanimalpinstheothertothegroundwithhisjawsaroundtheother'sthroat.

Anotherpatternisexhibitedbyastrangeanimalapproachinginasubordinateway.Thestrangerturnshisheadaway,hiseyesclosedandearsheldback,andattemptstomakeclosecontactwiththeotheranimalbyweavingaroundhimandleapingintheairwiththebackcurved.Thisbehaviorisoftendescribedas"courting"andindicatesafriendlyapproach.

Whiletheabovepatternsofbehaviorcanbeseeninalmostanybreedofdog,thefrequencyoftheirexpressionhasbeenhighlymodifiedbyselection.IntheoldEnglishsportofbullbaiting,dogswereurgedtoattackabull.Thebulldogbreedwasselectedforatendencytoattackthenoseofthebullandhangoninsteadofusingtheslashingattackfromtherearpreferredbywolvesandmostdogs.Again,inattackingsmallanimalstheusualbehavioristodashin,snap,andwithdraw,avoidinganyriskofinjury.Theterrierbreedshavebeenselectedfortheircourage,i.e.,thetendencytoattackpreyandkeeponattackingregardlessofanyinjurysuffered.Thisbehaviordependsinpartonthepossessionofunusuallytoughandinsensitiveskinontheneckandshoulders.Thesametendencyappearsintheirfightswithotherdogs,sothatfightsbetweenterriers

tendencyappearsintheirfightswithotherdogs,sothatfightsbetweenterriersoftengoontothedeath.

Otherbreedshavebeenselectedintheoppositedirection.Thescenthoundsareremarkablypeaceableanimals,rarelygettingintoseriousfightsevenamongstrangers.Thistraitisusefulinmanagingalargepackandenablesthemtobekeptingroupsinakennel.Thehoundsalsohavelong,bagginglipswhichcouldeasilybebittenbytheanimalhimselfinthecourseoffighting.Thesemaybearesult

ofselectionforgreaterpowersofscent,theanimaltastingaswellasscentingtheair,buttheyshouldalsotendtoinhibitfighting.

Thebird-dogbreedsarelikewiseunusuallypeaceableanimals,havingbeenselectedforpeacefulcoexistenceinkennellife.Inaddition,thesettersinmedievaltimeswereselectedforshowingthepatternofcrouchingbehaviorusefulinhuntingbirdswithanet,ratherthanthatofattack.Retrieversarestillselectedfora"softmouth,"aninhibitedbitesuchthatbirdswillnotbedamagedwhencarriedbacktothehunter.Inthemodernpointers,thehuntingdogisstillnotallowedtoattackthebirdsbutmuststandstillwhenhefindsthem.Inallbirdhuntingbreeds,thedoghastoberestrainedwhileatadistancefromitsmaster.Alltheseselectedtraitsresultinagreatreductionofagonisticbehavior.

Aspreviouslymentioned,theherdingdogshavealsobeenselectedfortheirabilitytobetrainedtorestraintheirattacks.Atthesametime,makingathreatenedattackisanessentialpartofgettingthesheeptomove.Inmanypartsoftheworld,herddogsalsoguardagainstlargepredators,includingwolves,sothattheolderherdingbreedswereoftenlargeandaggressiveanimals.Inthisrespecttheywerecloselyrelatedtotheguarddogsonceusedtoprotecthousesanddwellings.Shepherddogsstillservethisfunctiononmanyfarms.

Inancienttimes,guarddogsandwardogswereselectedfortheirferocityaswellassize.MastiffsandGreatDanesaremoderndescendantsofsuchbreeds.Theirancestorswereusedforattacksonthievesandmarauders,butinrecenttimesthesegiantbreedshavebeenselectedintheoppositedirection,andmostofthemareunusuallygentle.

Thepatternsofagonisticbehaviorhavethusbeensubjectedtogreatmodificationsinthedifferentdogbreeds.Comparedwithwolvestheyarehighlyspecializedintheirchoiceofpatternsofagonisticbehavior.Mostofthisspecialization,however,hasactedtointensifyordiminishthepatterns,rather

specialization,however,hasactedtointensifyordiminishthepatterns,ratherthantoalterthebasicorganizationofthebehavior.Theresultisthat,althoughalldogsshowsimilarpatternsoffightingwhensufficientlyaroused,itiseasytoincitesomebreedstofightandextremelydifficulttostimulateothers.

Investigatorybehavior.—Wolvesanddogsareprimarilyhuntinganimals.Theyfindtheirpreybysearchingforitratherthanbywaitingforittocometothem,andsincetheyfrequentlyspendmostoftheirdaysandnightsinhunting,theyshowthepatternsofinvestigatorybehaviormorefrequentlythanthoseofanyothersystem.

Wolvesarcunspecializedanimals.Theyhuntalargevarietyof

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gameandeatalmostanythingavailablewhenfoodisscarce.Inhuntingtheyusealltheirsenses;eyes,ears,andnose,whicheverisappropriate.Bycontrast,variousdogbreedshavebeenselectedfortheircapacitytolearnspecialkindsofhunting.Thescenthoundshavebeenselectedfortheirabilitytofollowatrail,althoughinactualfieldworkthehoundswillusetheirearsandeyesaswellanddoagreatdealofrandomexploration.Forexample,abeaglehuntingforaparticularobjectwillcircleoveragreatdealofgroundwithitsheadheldhighbeforeitfinallystrikesastrongairscent,thendropitsnosetothegroundandgooveritinchbyinchuntilitfindstheobjectwhichithassmelled.Suchdogsrarelyfollowascenttrailstepbystepbutrimrapidlyalongit,weavingbackandforthacrossthetrailwiththeheadheldmoderatelyhigh.Iftheylosethescent,theycircleuntiltheypickitupagain.

Attheoppositeextremearethesighthounds.Theselong-leggeddogswerefirstbredintheMiddleEast,wheretheArabsstillusesalukisforhuntinggazelles.Theyareprimarilyadaptedforrunningafterswiftpreyinopencountry,wherescentisoflittleimportance.AsimilarbreedistheRussianwolfhound,orborzoi,whichcanactuallyoutrunwolves,tiringthemuntiltheycanbecorneredandkilledbyahunter.

Thebirddogsusetheirsensesmuchmoreequally.Sincebirdsleavefewtracksontheground,thebirddogfindsitspreybyrapidquarteringoftheground,oftenunderdirection,andusuallylocatesitbyscentwhenafewpacesaway.Retrievershavetomarkthespotwherebirdsfall,andthisrequiresusingtheeyes.

Inadditiontohuntingandenvironmentalinvestigation,therearespecialpatternsofsocialinvestigationindogsandwolves.AsSchen-kel(1947)pointsout,therearetwoareasofparticularinterest,theheadandthetail,althoughsomeobserversreportthatwolvespaymoreattentiontotheheadthandodogs(Crisler,1958).Oneofthemostprominentpatternsisthemutualinvestigationoftheanalandgenitalregionswiththenose.Unlikethevariedinvestigatorybehaviorconnectedwithhunting,socialinvestigationisverysimilarinallbreeds.

Ingeneral,theinvestigatorybehaviorofthedogbreedsisnotstrikinglydifferentfromthatofwolves.Thechangeshavebeenchieflyproducedbyemphasizingordiminishingcertainpatternsandparticularlybystrengtheningorreducingtheeffectofcertainkindsofstimulation.Forexample,theshepherdbreedsseemtobehighlystimulatedbythesmellofsheeporevendeer,andtheyoccasionallybecomesheepkillersordeerhunters.Likewise,thebirddogsare

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highlystimulatedbybirdsandsometimesbecomechickenkillers.Bycontrast,manyterriershavelittleinterestinscent.Weputalivemouseinaone-acrefieldandthenletinagroupofbeagles.Theyfounditinlessthanaminute.Ittookagroupoffoxterriersaquarterofanhourtoaccomplishthesametask,andScottishterrierswereneversuccessfulatall.Atonepoint,oneofthemactuallysteppedonthemousewithoutnoticingit.Howthesedifferencesinbehaviorwerebroughtaboutisnotknownexactly.Fromtheiractions,foxterriersappeartobenotsomuchdeficientinthecapacityforscentassimplyuninterested.Theyare,however,highlystimulatedbysounds.

Conclusion.—Behavioralpatternsinthedogandwolfareessentiallythesame.Selectionhasparticularlymodifiedtheagonisticandinvestigatorysystemsofbehaviorandtosomeextentthesexualsystem.Thesemodificationsareusuallyquantitativeratherthanqualitative,andmostoftheminvolvethediminutionorexaggerationofanexistingpatternwithoutcreatinganythingessentiallynew.

Theninebehavioralsystemsofdogsandwolvesarerelatedtoeachotherincharacteristicways.Sexualandeliminativebehaviorareassociated,thelatterassistinginthelocationofmates.Likewise,inthesepredatoryanimals,investigative,agonistic,andingestivebehaviorarecloselyassociatedwitheachother.Thelastthreecanbeperformedinunisonaswellasindividually,sothatallelomimeticbehaviorisoftenalsoassociatedwiththem.Thuswehavea

allelomimeticbehaviorisoftenalsoassociatedwiththem.Thuswehaveapictureofthebasicbehavioralorganizationofdogandwolf.Essentially,thisisasystematicandobjectivewayofdescribingwhatiscommonlycalled"personality."

COMPARISONWITHHUMANBEINGS

Wecanusethemajorsystemsofsocialbehaviorasanoutlineforcomparinghumananddogbehaviorpatterns,foritisobviousthatallninebehavioralsystemsarealsowelldevelopedinhumanbeings.Whenwedothis,weimmediatelyfindthatthedetailedpatternsofbehaviorareverydifferent.Afterall,thedogisafour-footedanimalwithawell-developedtailandnohands.Particularbehaviorpatterns,therefore,areboundtobedifferent.Nohumanbeingcanwaghisnonexistenttail,andnodogcanpickupthingswithhispaws.Humanbeingsanddogsarcbasicallydifferentinanatomy,physiology,andbehavior.Atthesametime,socialbehaviorpatternsaresimilarenoughsothatmanyofthemaremutuallyrecognizableand

eachspeciescangiveappropriateresponsestotheother'sbehaviorinmanysituations.

Inattemptingtoascertainthepossiblebehaviorofprehistoricman,muchhasbeenmadeofthefactthatmanyprimitivehumansocietiesstillexistinginhistorictimesgettheirfoodbyasortofpackhunting(Etkin,1954).Thisisdifferentfromdogbehaviorinthatitisdoneentirelybymales,thefemalesandinfantsmakingtheircontributioneitherbyfoodgatheringorbyhelpingpreparemeatonceithasbeenobtained.Indogsandwolvesbothsexestakepart.Dogsreadilyjoininhumanpackhuntingwithoutanyparticulartraining,andevenpetdogswilljoininafightbetweentwochildren.Thislastisacasewherethedogrecognizesthehumanformofagonisticbehavior.Likewise,itiseasyforhumanstorecognizethefunctionofcaninegrowlsandbites.

Otherpatternsofbehaviorarenotsoeasytounderstand.Whenadogjumpsupwithextendedpawsandwaggingtail,mostadultsrecognizethisas"friendly"behavior,butasmallchildmaybefrightenedbyit.Evenanadultcanbemisled.Whenadogadvancesslowlywithtailheldstifflyerectandwaggingslowlyfromsidetoside,aninexperiencedpersonmayconcludethatthedogistryingtobefriendly.Onlycloseobservationofsuchbehaviorbetweendogsrevealsthatthislatterpatternusuallyprecedesafight.

Onegeneralcharacteristicofbehaviorwhichmakesdogshighlyadaptableas

Onegeneralcharacteristicofbehaviorwhichmakesdogshighlyadaptableasdomesticanimalsisthetendencytotreathumanbeingsasthoughtheywerefellowmembersofapack,evenifthe"pack"isreducedtooneothermember.Withthisgoesallelomimeticbehaviorandthetendencytojoiningroupattacks.Asecondisthedog'stendencytousethehumanhomeasadenanddefenditagainststrangers.Thelatterbehaviorisalmostuniversalinhumans,andmaygobacktoprimitivelifewhentheonlycommonlyavailableshelterswerecaves.

Wecanseethattherearecertainbasicsimilaritiesbetweendogandhumanbehaviorpatternsandsystems,andwemaynowconsidertheproblemofwhetherthereareresemblancesinthegeneticsystemswhichunderliethese.Inhumanprehistory,andindeedinmuchofhistoricaltime,themajorityofhumansocietiesweretribalvillages,eachconsistingofafewhundredindividuals,andeachvirtuallyisolatedfromothersbydistance,language,andsocialorganizationregulatingmarriage.Thiskindofpopulationisidealforgeneticchange,anditmayaccountfortherapidevolutionofthehumancapacityforlanguage.Thebeginningsofurbancivilization,

82BEHAVIORPATTERNS

some10,000yearsago,markedthebeginningoftheendofthesesmallisolatedgroups,andmodernhumanpopulationswiththeirenormousnumbers,greatmobility,andincreasingtendencytowardcrossbreeding,representasituationdesignedtoproducerelativegeneticstability.Dogsfirstbecamedomesticatedaboutthetimeurbancivilizationbegan,butforcenturiesafterwardeachtownandvillagehaditsowngroupofdogs,somewhatcutofffromothersbythesamesortofbehavioralmechanismsastheirhumanmasters,butwithpopulationsevensmallerandgenerationsturningovermuchmorerapidly.

Thiswasanidealsituationforgeneticchange,witheachvillagetendingtoproduceitsownvarietyofdog.Inadditiontothis,therewasthefactorofhumanselectionforwhatwereconsideredattractive,useful,orfashionabletraitsofappearanceandbehavior.Someofthethingswhichwereselectedwereobviouslynon-adaptivetoananimallivingundernaturalconditions,suchasbulldogheadsandshort,thinhair.Suchselectionmadegeneticchangemuchmorerapidindogsthaninhumanpopulations.Undermodernconditionswithscientificmethodsofselectionandartificialisolationofbreeds,suchchangescanproceedevenmorerapidly.

Aswehaveseenpreviously,thediversityofphysicalformproducedbythesemethodsisverygreat,muchgreaterthanthediversityinbehaviorpatterns.All

methodsisverygreat,muchgreaterthanthediversityinbehaviorpatterns.Alldogbreedsshowthesamefundamentalgeneralpatternsofbehavior.Thismeansthatbehavioralorganizationisrelativelyresistanttogeneticchange.

Thedogbreedshavesometimesbeencomparedtohumanraces.Theyare,however,basicallydifferentinthatthehumanraceshaveneverbeensubjectedtocontrolledsystematicselectioninfavorofparticularkindsofindividuals.Thereareafewphysicalcharacteristicswhichareadaptivetotheclimaticconditionsinwhichtheraceswereoriginallyfound.Forexample,apersonwithadarkskinandtightlycurledhaircancontrolhisbodytemperaturebetterunderhot,humidconditionsthancanapersonwithlightskinandstraighthair(Baker,1958),butmanyotherphysicaldifferencesseemtobeaccidental.BoththetallestandshortestofhumanbeingsarefoundinequatorialAfrica.

Onewouldexpectthatpopulationdifferencesinbehaviorpatternswouldbeevenlessmarked,andthisindeedseemstobethecase.Basichumanbehaviorpatternsaremutuallyrecognizablebetweenallhumanraces,eventhosewhicharemostdiversephysically.Inshort,wewouldexpectthatbehavioraldifferencesbetweenhumanraceswouldbemuchlessthanthosebetweendogbreeds.Inother

words,thisisnotausefultypeofcomparison.Thedogbreedsdonotcorrespondtohumanraces.

Ontheotherhand,inanyhumanpopulation,evenfromasupposedlypurerace,thereisanenormousamountofindividualvariability,bothinformandbehavior.Heretheconceptofpolymorphismisausefulone.Itwasoriginallyappliedtocasessuchascertainbutterfliesinwhichtwodifferentcolorvarietiesexistedinthesamespecies.Thehumanraceisobviouslypolymorphicwithregardtothetwosexes,andbetweenmatureandimmatureindividuals.Inaddition,thereareallsortsofdifferencesbetweenindividualsofthesamesexandage.Inahumansocialgroup,itisanobviousadvantagetohaveindividualsofdifferentabilitiesandskills.

Whenwelookatwolves,thewildancestorsofdogs,weseethattheyarealsopolymorphicinthattheyshowagreatdealofvariationinsizeandcolor(Jolicoeur,1959).Wecanalsoseethatitwouldbetheoreticallyadvantageousforawolfpacktobebehav-iorallypolymorphic:tohaveonememberwhichwouldbehighlytimidandreacttotheslightestsuspicionofdangerandthuskeepthepackonthealert,andanotherwhichmightbeboldenoughtogoinandobtainfoodwhendangerwasslightandtheneedforfoodgreat.

obtainfoodwhendangerwasslightandtheneedforfoodgreat.

Whatselectionhasdoneistotakethisindividualvariabilityofwolvesandaccentuateitinthedogbreeds.Wecanthinkofeachbreedasrepresentingoneofmanypossibleindividualbehavioralvariations.

Thisisthemostusefulcomparisonwecanmake.Adogbreedrepresentsalargegroupofgeneticallysimilarbutnotreplicatedindividuals.Humanfamiliesarealsogroupsofgeneticallysimilarindividualsbutareunlikedogbreedsbothintheirsmallsizeandinthefactthatoutbreedingisenforcedratherthanprevented.Inshort,wecanlearnrelativelylittleaboutthedifferencesbetweenhumanpopulationsthroughastudyofthedogbreeds,butagreatdealaboutthepossibilitiesofindividualvariationofhumanbehavior.

CHAPTER4

THEDEVELOPMENTOFBEHAVIOR

Sincethebasicbehaviorpatternsofdogsaresosimilartothoseofwolves,wewonderedhowsoonthedifferenceswouldappear.Wouldyoungpuppiesbelikelittlewolves,orwouldtheyshowdoglikecharacteristicsfromtheveryfirst?Again,howsoonwouldbreedcharacteristicsappear?Wouldallyoungpuppiesbeessentiallyalike,orwouldtheybegindevelopinginadifferentfashionfrombirth?Thesequestionsarerelatedtotheimportantpracticalproblemofthepredictionoflaterperformancefromearlybehavior.Weexpectedthatbywatchinganimalsastheygrew,wewouldseetheinteractionofhereditaryandenvironmentalfactorsastheymoldedbehavior,withtheprocessoflearningproducingamoreandmoreimportanteffectonbehaviorastheanimalgrewolder.Werealizedmanyoftheseexpectationsfromourobservations,buttheresultsalsoturnedupsomefascinatingfactswhichwehadnotforeseen.

Inordertogetourinformationondevelopment,webegansystematicdailyobservationsofeachlitter,asdescribedinChapter1.Theresultwassomeninety-sixpagesofnotesoneverylitterraised,andweanalyzedtheseaccordingtotheageofthepuppies.Aswewatchedtheanimalsfromdaytoday,theyhardlyseemedtochange.Butwhenwebegantoassembleournotesandobservations,wesawthattherewerecertaintimeswhenthebehaviorofapuppywouldchangeovernightandthatdevelopmentfellintodistinctnaturalperiods,eacliwithitsowncharacteristicbehavior.

THENEONATALPERIOD

THENEONATALPERIOD

Socialbehavior.—Whenwetakeapuppytwoorthreedaysoldawayfromitsmotherandplaceitonthefloorashortdistanceaway,

DEVELOPMENTOFBEHAVIOR85

itbeginstocrawlslowly,throwingitsheadfromsidetosideandwhiningoryelpingasitgoes.Thisvocalizationis,ofcourse,caresolicitingoret-epimeleticbehavior,andusuallyattractstheattentionofthemother.Ifshedoesnotrespond,thepuppykeepsoncrawling.Itdoesnotorientitselftowardthemotherandmaygoinacircleaftermovingafewinches.However,ifitsswingingheadtouchesthemotheroroneoftheotherpups,itstopsandcrawlstowardthem.

Wehavehereaninfantilepatternofinvestigativebehaviorwhichseemstobebasedentirelyonthesenseoftouch.Comparingthiswithadultbehavior,wenoticetwothings:eachmovementisextremelyslow,andthebehavioritselfisquiteinefficient,dependingchieflyonaprocessoftrialanderror.Itworkswellenoughifthepuppiesareconfinedtoanestboxorsomeden-likeenclosure,butiftheyarekeptinalargeroom,apuppyseparatedfromtherestislikelytomoveinanydirectionandendupfarawayfromthemother.Ofcourse,maternalbehaviorwillordinarilytakecareofthesituation,asmostmotherswillpickupyoungpuppiesandreturnthemtothenest.

Asecondsortofsituationoccurswhenthemotherhasleftthepuppiesforatime.Thepuppiesareheapedtogetherinaballinthecenterofthenest,restingquietly.Themothercomestowardthem,liesdownbesidethem,andstartspokingthemwithhernose,turningthemoverandlickingtheunderpartsoftheirbodies.Thisstimulatesthepuppiestourinateanddefecate,andthemotherkeepsonlickingthemuntiltheyarecompletelyclean.Fortheseyounganimals,eliminativebehaviorisareflexstimulatedbyanythingsimilartothemother'stongue.Puppiesraisedawayfromtheirmothersgetintoserioustroubleunlesstheyareproperlystimulatedwithawarmwettowel.Thenetresultofthesepatternsofbehaviorbymotherandoffspringisthatthenestareaisalwaysentirelyclean,showingnotraceofurineorfeces.

Meanwhile,thepuppieshavebeguntocrawl;andastheydoso,theycomeintocontactwiththemother'sbreastandbeginsuckingmovements.Inthemostcompleteformofthispatternofbehavior,thepuppypushesonthemother'sbreastwithalternateforepawsandoccasionallypullsbackwithitshead,bracingwithitsforefeetandpushingwithitshindfeet.Thisactivityprobablystimulates

withitsforefeetandpushingwithitshindfeet.Thisactivityprobablystimulateslactation,anditalsodisturbsanypuppieswhichhavenotbeenawakened,sothattheyalsopushforwardtoeat.Thisistheinfantileformofingestivebehavior.

Newbornpuppiesactuallyshowverylittleactivityotherthan

86BEHAVIORPATTERNS

thesesimplepatternsofet-epimeletic,investigatory,eliminative,andingestivebehavior.Theyreacttopain,cold,orhungerwiththesamelimitedrepertory,yelpingandmovingatrandom.Weseethatallbehavioratthisageisadaptedtoinfantilelifeandthatthecharacteristicpatternsofadultbehaviorarecompletelymissing.Infact,ifonehadonlybehaviortogoby,onemightassumethattheneonatalpuppybelongedtoanentirelydifferentspeciesfromadultdogs.

Sensorycapacities.—Theseobservationsstimulatedustostudythebasiccapacitiesunderlyingthedevelopmentofbehavior.Thefirstofthesewasobviouslythesenseorgans.Mostpeopleknowthatpuppiesarebornwiththeeyesclosed,whichmeansthattheycannotseeanything,intheusualsenseoftheword.Somepuppiesreacttoaverystronglight,particularlythosewithlightskinpigmentandwhoseeyelidsarethereforemoretransparent.

Whenweexamineanewbornpuppyclosely,wefindthatitsearsarealsotightlyshut,sothatthereisnoexternalopeningthroughwhichsoundcanenter.Whenwetestitwithsuddenloudnoises,thereisnoreactiontoeitherhighorlowtones.Thenewbornpuppyappearstobecompletelydeaf,inspiteofthefactthatitmakesconsiderablenoiseitself.Itprobablydoesnotevenhearitsownyelps.Inkeepingwiththis,wehaveneverobservedmotherscallingorvocalizingtotheiryoungpuppies.

Sinceadultdogsmakesomuchuseoftheirnoses,wemightexpectthatthesenseofsmellwoulddevelopearly.However,puppiescannotlocatetheirownmothersbyodorfromanydistance(James,1952),althoughTroshikhin(1955)gotresponsestoodoroussubstancesfromafewcentimeters.TheneurologistP.J.Harmanexaminedthebrainsofsomeofournewbornpuppiesformvelinationandconcludedthattheolfactorynervesandregionofthebrainconnectedtothemweresoundevelopedastomakeitunlikelythatthetruesenseofsmellhadanyimportantfunction.Wetestedthiswithacommercialcompounddevelopedtorepeldogsfromfurnitureandbushes.Theactiveingredientisrelatedtooilofcitronellaandisalmostodorlesstomosthumanbeingsalthoughthereisaslightlynauseatingaftertasteinthethroat.Itispossiblethereforethatthis

slightlynauseatingaftertasteinthethroat.Itispossiblethereforethatthissubstanceprimarilyaffectsthetastebudsratherthanthenose.Newbornpuppiesreacttoitbyacharacteristicwithdrawalreflex,drawingbacktheheadasfaraspossible.

Thesenseoftasteisobviouslypresent.Newbornpuppieswilllickaglassrodsmearedwithfishormeatjuiceormilkbutrejectabittersubstancesuchasquinine.Theywillsuckonanysmoothwarmob-

jectsuchasthehumanfingerbutkeepthisuponlyifmilkisforth-

ung.

Astotheothersensorycapacities,thepuppiesreactstronglytocold(^VYelker,1959)andpain.Givenachoicebetweenawarmheatingpadandacoldonenexttoit,theycometorestonthewannerone.Theyalsoreactnegativelytoextremeheatbuthavepoortemperaturecontrol,sothatonemusttakecare,inkeepingyoungpuppieswarmbyartificialmeans,nottoraisetheirbodytemperaturetoohighandkillthem.Anotherwell-developedsenseisthatofbalance,orresponsetogravitv.Turnedonitsback,thepuppyimmediatelystrugglestoturnover,andifitcrawlstotheedgeofatablesothatpartofitsbodyisunsupported,ityelpsindistress.Asshownbyresponsestothemother,reactionstotoucharewelldeveloped.

Comparedwithanadult,theneonatalpuppyisgreatlydeficientinsensorycapacities,beinginfactmostdeficientinthosesenseswhicharemostimportanttoanadultdog,i.e.,hearing,sight,andsmell.Fromasensorvviewpoint,theyoungpuppyisprimarilyatactileanimal,respondingtotouch,pain,andcold.Eveninhischemicalsenses,heislargelylimitedtotaste,whichiseffectiveonlyondirectcontact.Thepuppyisintouchwithonlythatpartofhisenvironmentwhichactuallytoucheshim.

Motorcapacities.—Themotorcapacitiesofthenewbornpuparelikewiselimited.Itsonlymethodoflocomotionisaslowcrawl,theactionofthefrontlegsbeingbetterdevelopedthanthatofthehindones.Thereisnotailwagging,andsuckingandlickingaretheonlyoralactivitiesotherthanvocalization.Thelatterconsistschieflyofdistressvocalization,aseriesofrapidwhinesoryelps.Neonatalpuppiesfrequentlymakethesenoisesataratefasterthanonepersecondwhilebeingweighed(Fig.4.1).Thepuppyisthusquitehelplessatbirth,althoughmoreadvancedthannewbornhumanbabiesinthatitisatleastabletocrawl.

crawl.

Capacitiesfororganizationofbehavior.—Earlyinourobservationsofnewbornpuppies,wenoticedthattheydidnotseemtolearnbyexperience.Apuppvwouldcrawltotheedgeofthescaleplatform,falloff,andbegintoyelpindistress.Whenplacedinthemiddleoftheplatform,itwoulddothesamethingoveragain.Likewise,theonlychangewesawinsuckingbehaviorwasthatthepuppiesbegantonursemorestronglyandefficientlyafteraweekorso,whichcouldhavebeencausedsimplybydevelopmentofthemuscularsystem.Somerecentexperiments(Stanleyetah,1963)indicatethatthepuppyiscapableofsomedegreeofslowlearningwithregardtosucking.Apuppywhichisgivenmilkaftersucking

88BEHAVIORPATTERNS

arubbernipplewilleventuallybegintosuckmoreoftenthanapuppywhichisnotsorewarded,andonewhichisgivenquinineinsteadofmilkwilleventuallyrefusetosuckthenippleatall.

Observingbehaviorisnottheonlvwayofinferringthefunctionofthecentralnervoussystem.Anothermethodistomakeamicroscopicexaminationofbraintissue.Nervefibersofyounganimalsfrequentlylackthemyelinsheathcharacteristicofadulttissue.Thissheathisanouterlayeroffatlikematerialassociatedwithspeedytransmissionofstimuli.Thefactthatanervefiberisunmyelinateddoesnotmeanthatitcannotfunctionbutonlythatitfunctionsmoreslowly.Myelinatedfibersinadultstransmitstimuli50to100timesfasterthantheunmyelinatedfibersofthesympatheticnerves.

Harman's(1958)investigationofthebrainofnewbornpuppiesshowsthattheonlvareaswhicharewellmyelinatedarethoseconnectedwiththetrigeminalnerve—whichgoestothemouthandincludesthesensorynervesoftasteaswellasthemotorfiberstothejawmuscles—andthenon-acousticportionoftheauditorynerve,whichisthepartconnectedwiththeorgansofbalance.Inthecerebralcortex,theconvolutionsaresimpleandtheunderlyingfibersalmosttotallvunmyelinated.Thedevelopmentofmyelinationthereforeseemstobecorrelatedwiththedevelopmentoffunction.Wewouldexpectthatstimulipassingthroughtheunmyelinatednervesofpuppieswouldmoveslowly,andcanconcludethattheslowactionsanddelayedresponsetimesofnewbornpuppiesresultfromthis.

Theundevelopednatureofthebrain,senseorgans,andmotororgansallresultinagreatlyreducedcapacityforlearningcomparedwiththatofolderpuppies.Theonlysenseorgansthroughwhichstimulicouldbeassociatedarethoseoftouchandtaste.Thesearelikewisetheonlyoneswhichcouldbeusedformakingdiscriminations.Thenumberofresponsesissolimitedthatthereareonlyafewactivitieswhichcouldpossiblybeaffectedbylearning:sucking,crawling,yelping,andelimination.Theresponsetimeisoftensoslow,occurringsecondsafterstimulation,thatapuppymighthaveconsiderabledifficultvinassociatingaresponsewithagivenstimulus.Wemustconcludethatthecapacityforlearninginthesenewbornanimals,ifitexistsatall,isquitelimitedandpossiblyofadifferentnaturefromthatintheadult.

Summary.—Thesocialbehaviorpatternsofthenewbornpuparelimitedtothoseconnectedwithneonatalexistenceandarequitedifferentfromthosefoundinadultanimals.Theentireneonatalperiodisprimarilydevotedtoonefunction,thatofobtainingnutrition

DEVELOPMENTOFBEHAVIOR

bynursing.Supplementingthebehaviorofthepuppiesisthatofthemothers,whorarelyleavethemevenforafewminutesduringthistime.Theneonatalpuppyisnotaself-sufficientorganism.Itstemperaturefluctuateswiththeenvironment,anditneedsthewarmthoftheotherpupsandthemother'sbody.Itevenneedsstimulationinordertofeedproperly,asnewbornpupswhicharekeptwarmwillliequietlyforhours,onlyattemptingtonursewhenstimulatedbythemother.

Anobserverofneonatalexistenceisstronglyimpressedbytheeffectivewayinwhichtheyoungpuppyisnormallyshieldedfromtheeffectsoftheexternalenvironment,bothbymaternalcareanditsownlimitedsensory,motor,andintellectualcapacities.Thepuppvcanbegreatlvdisturbedphysiologicallybyadverseconditions,buttherearefewwaysinwhichitcanbeaffectedpsychologically.

THETRANSITIONPERIOD

Duringtheentireneonatalperiodthepuppygrowsinsizeandstrengthbutstillretainsthesamepatternsofbehaviorasatbirth.Thefirstchangeinbehavioroccursaftertheeyesopen,whenthepuppyforthefirsttimecrawlsbackwardaswellasforward.Otherchangesfollowinrapidsuccession,sothatthepuppy

wellasforward.Otherchangesfollowinrapidsuccession,sothatthepuppyundergoesabehavioralmetamorphosiswhichisalmostasspectacularasthemetamorphosisofformfromatadpoletoafrog.Behavioralpatternsadaptedforneonatallifearedecreasedorabandoned,andthecharacteristicpatternsofadultbehaviorbegintoappear.Theperiodisoneoftransitionfromneonataltoamoreadultformofexistence.Thisprocessbeginswiththecompleteopeningoftheeyes,occurringontheaverageat13daysofage,withmuchbreedandindividualvariation(Table4.1).

Changesinsocialbehaviorpatterns.—Theneonatalpuppyischaracteristicallydifficulttofeedbyhand.Itsucksonlyhalfheartedlyonababy'snursingbottle,apparentlybecauseitisdifficulttoduplicatetheexactprimarystimuliorreleaserswhichtriggerthenursingpattern.Itcanbefedafewdropsatatimewithaneyedropper,thepuppymakingfutilesuckingmovements.Itdoesnotlapmilk,andtheeasiestwaytofeedaneonatalpuppyistoinsertasmallstomachtubeandinjectmilkdirectlyintothestomach.

Bycontrast,thepuppyat2weeksofageishighlyadaptable.Itwillreadilynursefromabottleandcanevenlapupmilkorsoftfoodfromadish,albeitinaclumsyfashion,usuallyplasteringitself

90BEHAVIORPATTERNS

TABLE4.1TimeofCompleteOpeningoftheEye

*Allbreeds(orhybrids)weightedequaDy.

tIncludesoneretardedlitter.

Openingoftheeyeoccursearlyinbeaglesandcockerspaniels,moreslowlyinbasenjis,andstillmoreslowlyinsheltiesandfoxterriers.Inthehybrids,BCSFi'sandFVsarerelativelyslow.Whenallhybridsaretakentogether,theaverageisintermediatebetweenthetwoparentbreeds.

withfoodandoccasionallychoking.By3weeksofagethepuppyisabletostandanddrinkmilkoreatinafairlyefficientfashion.However,itsfirstteethhaveonlyjustbeguntocomethrough,anditisstillincapableofdoinganyeffectivechewing.Whenherpuppiesareabout3weeksofage,themotherbeginstovomitwarm,semiliquidfoodfromherstomach,thisbeingthenaturalsupplementalfoodatthisage.

Wehaveextensiveevidence,obtainedbysuddenweaningatdifferentages

Wehaveextensiveevidence,obtainedbysuddenweaningatdifferentages(Scott,Ross,etal.y1959),ontheabilityofyoungpuppiesinthetransitionperiodtoeatinwaysotherthannursing.Artificialbitches'milkandpowdereddrydogfoodwasavailableatalltimestothepuppies,andwehelpedthemtofindthedishwhentheyweretooyoungtolocateitbythemselves.Beforeandafterweaning,wetestedthemtwiceadaybystickingafingerintotheirmouthsandrecordingtheamountandforceofsucking.Until19or20daysofage,thepuppieswouldsuckfingersreadilv,particularlywhenhungry.Afterthisage,therewasnodifferencebetweenexperimen-talsandcontrolsleftwiththemother,andby4weeksofageallthepuppieshadquitfinger-suckingentirely.Theymightgentlychew,butthebehaviorofsuckingonobjectswhichdidnotproducemilkhaddisappeared.Allofthisevidencemeansthattheonlypattern

ofingestivebehavioravailabletothenewbornpuppyissucking.Alternatepatternsoflappingandchewingbegintoappearinthetransitionperiod,andthepuppyiscapableofabandoningsuckingatanytimethereafter,providingthepropersortoffoodisavailable.

Aspartofthesameexperiment,partofalitterwastemporarilyremovedfromthemotherandplacedintheotherhalfofthesameroom,separatedbyawirebarrierthroughwhichdieanimalscouldseebutnottouchtheothers.Weleftthemforseveralhours,andthencamebacktoobserve.Duringthefirstweekoflife,theymightbefoundanywhereintheirhalfoftheroomandoftenseparatedfromeachother.Duringthesecondweek,weusuallyfoundthemtogetherinthesamespotwherewehadleftthem.Inthethirdweek,aftertheireyeswereopen,wealwaysfoundpuppiesclosetothefence,indicatingthattheywerenowabletoorientthemselvesintheroom.Thedevelopmentoftheeyesisthusaccompaniedbyachangeinthepatternofinvestigativebehavioratthestartofthetransitionperiod.However,themoststrikingchangeininvestigativebehavioroccurslater,atabout3weeksofage,whenthepuppiesbegintorespondtopeopleorotheranimalsatadistance.Allthisevidenceindicatesthattheearlypatternofinvestigativebehaviorbasedontouchisgivingwaytoadultpatternsofbehavioremployingothersenseorgans.

Et-epimeleticbehaviordoesnotdisappear,butsomeofthesituationswhichonceevokeditarenolongereffective.Forexample,theamountofvocalizationwhilethepuppiesarebeingweigheddropstoalowlevelby2weeksofage,andalmostdisappearsafter3weeks(Fig.4.1).Atthesametime,theybegintowanderaroundandyelpwhenmovedtoastrangeplace,eventhoughwarmandcomfortable.Untilthisage,theywouldbequietanywhereaslongastheywere

comfortable.Untilthisage,theywouldbequietanywhereaslongastheywerenotcoldorhungry.

Eliminativebehavioralsobeginstochangetowardtheadultpattern(Ross,1950).By3weeksthepuppiesarebeginningtowalkoutsidethenesttourinateanddefecate.Theynolongerrequirestimulationbythemother,althoughtheystillhavenotbeguntousespecificspots.Mostmotherscontinuetolickandcleantheirpuppies,buteliminationisnolongerdependentonthisstimulation.

Agonisticbehavioralsobeginstoappear.Somepuppieswillgrowlasearlyas2weeksofageifgivenabone;andafter3weeks,playfulfightingwithotherpuppiesbecomesincreasinglycommon.Thepuppiespawandmoutheachotherclumsily,apatternwhichwilleventuallybecomemoreandmorelikethefightingofadults.Before2weeksthereisverylittleindicationofescapebehavior.Thefirst

BEHAVIORPATTERNS

indicationisbackwardmovementinreactiontovisualstimulation,whichwecanthinkofasavisualstartlereaction.Later,at18to20daysontheaverage,thepuppiesfirstbegintoshowastartleresponsetosound.

Oneoftheneonatalpatterns,shelter-seeking,changesrelativelylittleexceptthatthepuppiesaremorelikelytobefoundseparated

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AGEINWEEKS

Fig.4.1.—Declineoftherateofdistressvocalizationduringthefirst4weeksoflife.Notebreeddifferences.Thesereactionswereobtainedwhilethepupswereweighedandprobablymeasurediscomfortresultingfromcontactwiththecoldmetalscaleplatform.

fromeachotherwhentheroomiswarm.Thisprobablyreflectsanincreasingabilitytomaintaintheirownbodytemperatures.

At3weeksofagetherearestillthreeimportanttvpesofadultbehaviorwhicharecompletelymissing:sexual,allelomimetic,andepimeletic.Thefirsttwowillappearinthenextfewweeks,butthethirdwillbeconfinedtoself-groominguntiltheanimalsbecomeadults.

Thisisthegeneralpictureofchangeinsocialbehaviorpatterns.Thepuppyat3weeksisafardifferentanimalfromaweekearlier.


Sincesuchimportantchangesoccur,theirtimingbecomesquiteanimportantmatterforunderstandingbehavioraldevelopment,andoneofthebestwaystoapproachthisproblemistoexaminechangesintheunderlyingbasiccapacitiesoftheanimal.

Senseorgans.—Assoonastheevesopenwecandemonstratethattheyare

Senseorgans.—Assoonastheevesopenwecandemonstratethattheyarefunctionalbyshiningabrightlightintothemandobservingthecontractionofthepupils.However,insomepuppiesthisisslow,andthepupilkeepsfluctuating,indicatingthatthemechanismisnotcompletelydeveloped.Thepuppieswillshownystagmus,whichmeansthatifweholdapuppy'sheadandbodyfirmlyandswingthewholeanimalinahorizontalarc,hiseyeswillflickbackandforthasifhewerefixinghiseyesonanobjectandfollowingitasitmovespast.However,thismavmeanonlythatareflexinvolvingthesemicircularcanalsoftheearisfunctioningandnotthatthepuppyisrespondingtosight.Ahistologicalexaminationoftheeyesshowsthattheretinaattwoweeksofageisquiteundevelopedand,infact,isnotcompletelyformeduntilapproximately4weeksofage,indicatingthatcompletevisualfunctionhasnotyetbeenachievedduringthetransitionperiod(Blume,1956;Parry,1953).

Anotherindirectlineofevidenceisprovidedbythealpharhythmofthebrainwaves.Thiselectricalactivityofthebrainisassociatedwiththedevelopmentofvisualfunctionandindicatesactivityinthatpartofthecerebralcortexassociatedwithvision.CharlesandFuller(1956)measuredtheelectricaloutputofthebrainindevelopingpuppies,usingsurfaceelectrodes.Thenewbornshowalmostnobrainwavesandnodifferencebetweenthesleepingandwakingstates.Thenatapproximately3weeksofage,theelectroencephalo-graphicpicturechangesradically.Thebrainwavesincreaseinamplitude,andanEEGtakeninsleepbecomesdifferentfromthatrecordedduringthewakingstate.However,theEEGdoesnotshowitsadultformuntil7or8weeksofage,whenthenervoussystemisprobablylikethatofanadultasfarasvisionisconcerned.

Stillanotherwayofmeasuringthedevelopmentofperceptionisthe"visualcliff"testofWalkandGibson(1961).Theapparatusconsistsofa6-inchwideboardlaidacrossapieceofplateglass.Ononesideoftheboardtheglassislaiddirectlyoverasheetofcheckeredcloth;ontheothersidetheclothfallsaway,producingtheillusionofadrop-offfromtheboardtothefloorbelow.Disregardingtheglass,onesideappearsdeepandtheothershallow.Mr.FrankClarktestedpuppiesonthisapparatusfromthetimeofeyeopeninguntiltheyshowedanaversiontothe"deep"side.Untiltheywere

BEHAVIORPATTERNS

about30daysold,puppiessteppedfromtheboardindiscriminatelyontoeitherside.Afterthisage,mostpuppiesuniformlywenttotheshallowsideinspiteofprevioussafelandingsonthedeepone.

Summarizingthisevidence,wecanconcludethatwhilethepuppyrespondstolightassoonastheeyesopenandsometimesbefore,itisprobablynotfullycapableofobservingformuntilabout4weeksofage,andthatcompletevisualcapacityisnotpresentuntilabout8weeks.

Thestartleresponsetosound,whichisthefirstindicationthatthesenseofhearinghasbeendeveloped,appearsat19.5daysontheaverage(Table4.2).Whetherthesenseofhearingiscompletelydevelopedatthispointwedonotknow,butthepuppiesseemtorespondtoanyloudnoise,whetheritisarelativelyhigh-pitchedsoundoftheGaltonwhistleoralow-pitchednoisefromanyothersource.Thestartlereactiontosoundisadefiniteandeasilyrecognizedreaction,andsinceitiscloselyassociatedwithanumberofotherchanges,itcanbetakenasthebestmeasureoftheendofthetransitionperiod.

Changesinmotorcapacities.—Duringthetransitionperiod,the

TABLE4.2TimeofFirstFunctionoftheEar:AnimalsGivingaStartleResponsetoSound

*Allbreeds(orhybrids)weightedequally.


Thedevelopmentofthiscapacityshowsmuchlessvariabilitybetweenbreedsthantheopeningoftheeyeor

eruptionoftheteeth.Thusthestartleresponsecanbetakenasanexcellentdevelopmentalmarker,closelyasso-iiatedwiththebeginningoftheperiodoisocialization.Contrarytootherindicators,foxterriersaremoreadvancedinthisrespeitthanotherbreeds.Thehybridsdevelopfasterthaneitherparentstrain,butthereisstillatendencyfortheBCSgroupofhybridstofallbehind,asinothermeasures.Thisdifferencebetweentheresultsofthereciprocalcrossesmightbeattributedtoeitheramaternaleffectoraccidentalselectionofslowandrapidlydevelopingparents.


95

puppybeginstogetuponhisfeetandwalkinsteadofcrawl(Fig.4.2).Themostaccurateobjectiveevidencewhichwehaveontheonsetofthisabilityisthe

accurateobjectiveevidencewhichwehaveontheonsetofthisabilityistherecordofthepostureofpuppieswhenweighedeachweek(Fig.4.3).Atbirthandforthenexttwoweeklyweighings,almost100percentofthepuppieslieflatwhenplacedonthescales.At3weeks,50percentofthemadoptsomeotherposture;andby4weeks,veryfewofthepuppiesstilllieflat.Thisdoesnotmean,ofcourse,thattheycannotstand,asobservationshowsthatallthepuppiescanwalkby3weeksofage,butonlythat

100

75

ui

o

tr50

25

10

15AGEINDAYS

20

25

30

Fig.4.2.—Developmentofwalkingandplayfulfightinginrelationtotheopeningoftheeyes,startleresponsetosound,anderuptionoffirstteeth.Thegraphsrepresentcumulativefiguresoffirstoccurrencesinanimalsobservedin10-minutedailyperiods.Thezeropointisthedaybeforethefirstanimalwasobservedwalkingorshowingplayfulfighting.

someofthemstillreactbylyingdownwhenplacedinastrangesituation.

Anotherimportantchangeinmotorcapacitiesarriveswiththeeruptionofthefirstteeth(Table4.3).Inpuppiesthesearetheuppercanines,whichcanfirstbefeltthroughthegumsatapproximately20daysofageontheaverage.Alongwiththisthepuppiesbegintobiteandchewaswellassuck.Allmovementsare

withthisthepuppiesbegintobiteandchewaswellassuck.Allmovementsarestillslowandclumsycomparedwiththoseofadults,butthepuppiescanatleastchewandmoveintheadultfashion.Anothermotorcapacitywhichappearsasoneofthenewpatternsofsocialbehaviorinthisperiodistailwagging.

BEHAVIORPATTERNS

100

80

bJId

u.

z60o

j-zu

o40tr

UQ-

20-

AGEINWEEKS

Fig.4.3.—Developmentofmotorabilityduringthetransitionperiod,asshownbythepercentageofanimalswhichstayedontheirfeetinsomeposture(standing,crouching,orsitting)whenfirstplacedonthescaletobeweighed.Notethathybridsdevelopedmoreslowlythanpurebreeds,possiblybecauselargerandheavier.

TABLE4.3

TimeofEruptionofUpperCanineTeeth

•Allbreeds(oihybrids)weightedequally.


Thepun-breedsvarywidelyinthischaracteristic,basenjisandbeaglesbeing

Thepun-breedsvarywidelyinthischaracteristic,basenjisandbeaglesbeingfast,andtherestslow,particularly

folterriersInthehybridsthereisatendencyfurallpopulationsintheBCScross(startedfromcockermothers)todevelopmoreslowlyIftheretardedlitterisomittedfromtheCSBFi,thepercentageatiweeksis74,almostexactlythesameasthatinthebackcross,suggestingthatmaternalenvironment(perhapsprenatal)hasaneffectontheeruptionofteeth.


Learningcapacities.—Oneofthebestwaystostudylearningobjectivelyisbythemethodofconditioning,originallydevelopedonthesalivaryreflexofthedogbyPavlov.Inthistypeofexperimentthedogisstimulatedinsomeway,usuallybyasoundorlight,andpresentedimmediatelyafterwardwithapieceofmeat.Beforelongthedog'smouthbeginstowaterassoonasthestimulusappears,andbeforehehasachancetoseethemeat.Thisprocessofforminganassociationbetweenaneutralorinitiallymeaninglessstimulusandaresponse,iscalledconditioning.Inordertodoiteffectivelytheremustbeaprimarystimulus,whichproducesaresponsewithoutpreviousexperience,andanothersecondaryorneutralstimulus,whichhasnosucheffect.Thelatterisdifficulttofindforayoungpuppy,sincetherearesofewstimulitowhichitcanrespond,andmanyoftheseproduceprimaryresponsesthemselves.

Changesintheabilitytobeconditionedcanbemeasuredinthefollowingways.Oneistotakethenumberoftimesthattheneutralandprimarystimulihavetobepresentedtogetherbeforearesponseisobtainedtothesecondarystimulusalone.Adultdogswillfrequentlymakesuchanassociationwithoneexperience.Asecondwaytomeasurethiscapacityistomeasurethenumberofpairingsnecessarybeforetheassociationwiththeneutralstimulusbecomesstable.Instableconditioningtheanimalrespondstotheneutralstimulusinverynearly100percentofthetrials.Stillathirdmethodistosetsomearbitrarystandardofaccomplishmentandseehowlongittakestheanimaltomeetthecriterion.

Inourownexperimentswefirstsetthearbitrarystandardofobtainingastableresponseaftertentrials(Fuller,Easier,andBanks,1950).Insteadofusingthesalivaryreflex,whichwouldbedifficulttomeasureinyoungpuppies,weemployedtheleg-withdrawalreactiontoamildelectricshockandappliedthistechniquetotwenty-fivepuppies,includingcockerspaniels,shelties,wire-hairedfoxterriers,springerspaniels,andabeagleXKerryblueterrierhybrid.Avarietyofneutralstimuliweretested,includingthesoundofabuzzer,light,touch,the

ofneutralstimuliweretested,includingthesoundofabuzzer,light,touch,thetasteofKarosyrup,andtheodorofadogrepellant.Noneofthepuppiesdevelopedstableconditionedreflexesaftertentrialsuntiltheywerebetween18and21daysold,althoughthereweresignsofunstableresponsesasearlyas14days.Ineachcasetheonsetofstableconditioningwasquitesudden.Onedaythepuppymightgiveoccasionalresponsesandonthenextitwouldgiveastablereactionaftertentrials.

Thetypeofreactionwhichthepuppiesgaveafter18daysistypicalofolderpupsandadults,andwecanconcludethatthere

isanimportantchangeinthecapacityforconditioningatthisage.Inalaterexperiment,weworkedwithalessextremecriterionforconditioning,withtheideaofobtainingabettermeasureoftheearlydevelopmentofthelearningcapacity(CornwellandFuller,1960).Inthiscasethepuppymetthestandardwhenitbegantorespondtotheneutralstimulusin50percentofthetrials.Wealsousedapuffofairastheneutralstimulus,thisbeingsomethingtowhichthepuppiescouldreactveryearlyindevelopment.Asampleoffivefoxterrierpuppiesmetthe50percentrequirementatanywherefrom10to19daysofage,withanaverageofabout15days(Fig.4.4).Thiskindofcriterionapparentlygivesamuchmore

Fig.4.4.—Developmentoflearningcapacitiesduringtheneonatalandtransitionperiods.Eachcurverepresentstheaveragescoreoffivefoxterrierpuppiesgiven10trialsperday.Notethatthereisnoevidenceofimprovementuntilatleast10daysofage(after50previoustrainingtrials)andthattheexperimentalanimalswerestillnotmakingperfectscoresat17days.Therewasconsiderableindividualvariation,andnumbersaretoosmalltogiveaclear-cutdevelopmentalpicture.

variableresultthanthemorerigorousone,butitneverthelessdemonstratesthatconditioningofanunstablesortdoesappearatsometimeinthetransitionperiod.

TheseresultsesentiallyagreewithworkbyRussianexperimenters(Klyavina,etah,1958).Workingwithauditorystimulationat15daysofage(atwhichtimeourresultsindicatethatonlyafew


puppieswouldrespondtosound),theyfoundthattheleg-withdrawalresponse

puppieswouldrespondtosound),theyfoundthattheleg-withdrawalresponseappearedataboutthesixteenthpairingandbecamestablebytheeightieth.Thisisconsistentwithourresultsasthesepuppieswouldnothavepassedatentrialcriterion.Atonemonth,learningwasasrapidasthatobservedbyusbeyondtheageof3weeks.

80-SHOCK,STABLE

tn<

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20

Neonatol*|PeriodofSocializationPeriod\-

TransitionPeriod

FOOD,.STABLE\\\\

N

SHOCK

\

\

FORMATION'^.^v

FOOD*^V

NATION**««■*■».»««,..ZZZZZZ

FORMATION

10203040506070

AGEINDAYS

AGEINDAYS

Fig.4.5.—Changeinresponsetoconditioningbetweenthetransitionandsocializationperiods.Thecapacityforformingaconditionedresponsetofooddevelopsbeforethatforelectricshock.(DatafromKlyavinaetal.,1958.)

TheRussiansalsofoundthatamotorresponsetofoodcouldbeconditionedmorerapidlythanthewithdrawaltoshock.At15daysthisresponseappearedontheaverageaftertheninthpairingandbecamestablebythethirty-seventh.Thesepuppiesstillwouldnothavemetaten-trialcriterionforastableresponse,buttheexperimentindicatesthattheabilityforconditioningingestivebehaviorappearssoonerthanthataffectingagonisticbehavior.Whilethesefindingsarenotasclear-cutaswemightdesire,allresultsindicatethatthepuppydevelopstheabilitytoquicklymakeanassociationconcerningapainfulexperienceneartheendofthetransitionperiod.

Thisraisesthequestionofwhetheranemotionalresponsetopainmightbelearnedearlierindevelopment.However,whenwetriedtoconditiontheincreaseinheartrateinresponsetopain,wefoundthatthisabilityactuallyappearedlaterindevelopment(FullerandChristake,1959).Ifthisistrue,itsuggeststhatthepuppyinearlydevelopmentishighlyprotectedfromthepsychologicalafter-effectsofunpleasantexperiences.

Stanley(1963)hasdevelopedanewmethodofstudyingchangesincapacitiesforconditioning,basedonoperantconditioning.Intheoperanttechnique,firstusedbySkinneronadultanimals,thepuppymustassociatewhathedoeswiththeresultingchangeinstimulation.Thisavoidstheproblemoffindingneutralstimuliandiscloselyrelatedtothenormalprocessofnursing.Thepuppyfirstsucksand,asaresult,isstimulatedbymilk.Thereisatheoreticaldifficultyarisingfromthepossibilitythatmilkitselfmaybeaprimarystimulusforsucking.Ifso,thenursingprocesscanbeexplainedasacircularreflex:suckingisstimulatedbycontactwithasoft,warmsurface;suckingproducesmilk;andmilkstimulatessucking.

Stanleyhasthereforedevisedanelectronicmother,orratheranelectronicbreast,whichcanbesettoreleasemilkafteranygivennumberofsucks.Thepuppiesrespondasiftheywerelearningthatthemachinegivesmilk,butwehaveasyetnoinformationonhowsoonthisabilitytolearndevelopsorhowitchangeswithage.

Summary.—Allourevidenceshowsthatthetransitionperiodisoneofprofound

Summary.—Allourevidenceshowsthatthetransitionperiodisoneofprofoundreorganizationofbehavior.Byselectingtheopeningoftheeyesasthebeginningofthetransitionperiodandtheappearanceofthestartlereactiontosoundastheend,wefindthatthewholeprocesstakeslessthanaweek,theeyesopeningcompletelyat13daysandthestartlereactionappearingat19.5days.Thesefiguresaretheaverageofthefivebreedsstudied.Amongthem,theprocessmaybefasterinsomebreedsthaninothers.Furthermore,agreatmanyofthesechangesseemtobeconcentrated—againontheaverage—around18to19daysofage,particularlythoseinvolvingachangeinbehavior.Thepuppythusbecomesaverydifferentorganismwithinthespaceofafewdays.

Themostessentialchangeinfunctionisfromtheneonataltotheadultformofnutrition.Thechangeisnotabsolute,asthepuppiesstillcontinuetonurse;buttheynowbegintoeatlikeadultanimalsaswell.Anotherfundamentalchangeisfromtheneonataltotheadultformoflocomotion.Thepuppiescannowwalkandarecapableofleavingthenestarea.Anotherimportantchangetakesplaceintherelationshipwiththemother.Previously,therelationshipwas

quitesimpleandinvolvedingestivebehavioralmostentirely.Nowitbecomesmorecomplexasotherbehaviorpatternsappear.Inaddition,thepuppychangesfromananimalwhichishighlyprotectedfromitsenvironmenttoonewhichisextremelysensitive.Asweshallsee,thischangeisassociatedwith,andperhapsnecessaryto,theformationofprimarysocialrelationships.Italsomeansthatanyonesortofenvironmentalstimulationhasaverydifferenteffectonthebehaviorofthepuppyatdifferentages.

PERIODOFSOCIALIZATION

Thisisaperiodofrapiddevelopmentofsocialbehaviorpatterns,incontrasttothetransitionperiod,whichischieflyoneofchangesinbasicsensoryandmotorcapacities.Mostofthenewpatternsofbehavioraredirectlyconnectedwiththemotherandlittermatesandformapartoftheanimal'srapidlydevelopingsocialrelationships.

Ingestivebehavior.—Intheneonatalperiod,themotherconstantlyattendedthepuppies.Nowshebeginstoleavethemforlongperiods,andwhenshereturns,shemayvomitfoodforthepuppiesaswellasallowingthemtonurse.Thisbehaviortypicallybeginsbetween3and4weeksafterthebirthofthepups.Frequentlyshewillnotliedownwiththem,andtheyhavetorunafterherandnurseasshestandserect.Thepuppiesreadilyeatthevomitedfoodandwillalso

nurseasshestandserect.Thepuppiesreadilyeatthevomitedfoodandwillalsolapupwaterormilkwhenavailable.

Weaningisagradualprocess,startingwithvomitingbythemotherandthetakingofsolidorsemisolidfoodbythepups.Whentheyareabout5weeksold,themothermaybegintogrowlatherpuppieswhentheytrytonurse.Thepuppieswalkuptoher,starttonurse,andthemotherquicklyturns,growls,andsnapsintheirfaceswithoutactuallytouchingthem.Thesurprisedpuppiesoftenrolloverontheirbacks,yelping,andsoonlearntostayaway.Somemothersstopproducingmilkasearlyas7weeksafterthepuppiesareborn,butafewstillproduceitat10weeks,sothatfinalweaningtosolidfoodnormallytakesplacesometimewithinthisperiod.

Thepuppyisstillnotcapableofeatinglikeanadult.Itssmallbabyteetharesharp,butincapableofproducinganyeffectonsolidbones.Likewise,thepuppyisstillincapableofdoingitsownhunting.

Eliminativebehavior.—Earlyinthesocializationperiod,thepuppybeginstoleavethenesttourinateanddefecate.Atfirstthisisdoneinanyspotcloseby,butby8.5weeks,thepuppyisbe-

ginningtousedefinitespotsfordefecation(Ross,1950).Itwillwanderaroundthepenwithitsnosetotheground,apparentlyfollowingatrail,butmoreprobablysmellingtracesofurineorfecessothataneliminativereflexissetoff.Thepuppyatthisagewillgoformanyhourswithoutsoilingitssleepingplacebutwillurinateanddefecatefrequentlywhileawakeandactive.Inmostcasesthechosenspotisasfaraspossiblefromthefoodareainthepen.Themalepuppystilldoesnotshowtheleg-liftingreaction.

Thesebasicpatternsofdevelopingeliminativebehaviorhaveconsiderablepracticalimportancetothedogownerwhoisattemptingtohousebreakapuppy.Theimportantfactsare:first,thatapuppywillnotsoilitsownsleepingplaceandwillnoturinateordefecateifshutupinitovernight.Thisprobablyhappensbecausepartofthenormalpatternofeliminationisthepreliminarymovingaroundwhichisnotpossibleinarestrictedarea.Thesecondfactistheresponseofthepuppytoodorsofpreviouseliminationinparticularspots.Thislatterbehavioristhepreliminarytothe"scentpost"behaviorofadultanimals.Oncethesespotsareestablishedandnotcompletelydeodorized,urinationanddefecationcanbereadilycontrolled.Thewisedogownerhelpsthepuppyestablishthesespots,eitheroutdoorsorindoorsonpapers,andleadsthepuppytothematfrequentintervals.Untilitis12weeksold,apuppyislikelytourinate

tothematfrequentintervals.Untilitis12weeksold,apuppyislikelytourinateordefecateeveryhourortwo,aslongasitisawake.

Et-epimeleticbehavior.—Thedistressvocalizationofpuppiesnowbecomesmoredifferentiated,thepuppiesmakingagreatervarietyofsounds.Theystillyelpwhenhungryorhurtbutarenotsolikelytobecomecoldandvocalizeforthisreason.Inaddition,certainnewreactionsappear.Oneisyelpinginreactiontorestraint.Wefirstnoticedthisinpuppieswhichaccidentallygotcaughtbehindanestboxandsoonfoundthatsimplyconfiningapuppyinasmallboxwouldproducethesamereaction.Removalofthemotherandlittermateswouldalsocausethepuppiestoyelp,butoneofthemosteffectivesituationswasastrangeplaceawayfromthehomepen.Puppiesplacedinacageinthehalloutsidetheirhomepenmadeanear-splittingracket.

Usingthisinformation,we(ElliotandScott,1961)madeadevelopmentalstudywhoseresultsareshowninFigure4.6.Puppiesleftaloneintheirhomepensdoonlyamoderateamountofyelpingat3weeksofage,andthistendstodecreaseastheygrowolder.However,apuppyleftaloneinastrangeplaceyelpsloudlyandcontinuously,producingthemaximumnumberofvocalizationswhen


103

1400

1200

1000

<n

800

geoo

<oo

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400

200

T-

10

II

12

WEEKSOFAGE

Fig.4.6.—Developmentofdistressvocalizationofbeaglepuppiesundertwoconditionsofisolation.Notethatthepeakofvocalizationinastrangepencomesat6-7weeksofage,whichotherevidenceshowstobethepeakofdevelopmentofthecapacityforrapidsocialization.

itis6to7weeksoldandgraduallydecreasingthemthereafter.By12weeks,itmakesverylittlenoiseinastrangeplace.Thistrendreflectsaprocessofmaturationalchangeratherthanbecominghabituatedtothesituation,becauseapuppygiventheexperience

forthefirsttimeatthelateragesshowsmuchthesameyelpingrateasthosewhichhavebeenisolatedbefore.

Wecaninterpretthisbehaviorasadevelopingemotionalreaction.Forahighlydependentandhelplessanimallikeayoungpuppy,themostdangerouspossiblesituationisoneinwhichitiscompletelyaloneinastrangeplace.Undernaturalconditionsalostwolfpuppywouldbevulnerabletoanypredatoraswellasindangerofeventuallystarvingtodeath.

Thisreactionalsoindicatesanotherfunctionoftheperiodofsocialization—thatofbecomingattachedtoaparticularlocality.Thepuppyisatfirstlittledisturbedbyachangeinlocality,becomesgreatlydisturbedaround6or7weeksofage,andstilllater,atatimewhenpuppiesnormallybegintoexploretheirenvironmentatadistancefromtheirsleepingplaces,becomeslessdisturbedbyit.

Investigatorybehavior.—Oneoftheoutstandingchangesinbehavioratthebeginningoftheperiodofsocializationisthetendencyofpuppiestorespondtothesightorsoundofpersonsorotheranimalsatadistance.The3-week-oldpuppyapproachesslowlyandcautiouslytowardahumanobserverseatedquietlyinitspen.Itfinallycomescloseandstartsnosinghisshoesandclothes.Afterthis,itmaystarttowagitstailrapidlybackandforth.Thetailwaggingitselfappearstohavenodirectlyadaptivefunction,butissimplyanexpressionofpleasurableemotiontowardasocialobject.Whateffectithasonotherdogsisdifficulttotell,butitseemstohavethesameeffectonhumanobserversasthesmileofachild;i.e.,itisarewardforthepersonwhohasinitiatedasocialcontact.Forthepuppy,thiswholepatternofbehavioristhetypicalmethodofinitiatingasocialrelationship,anditmaydevelopfurtherintotheplayfulbehaviordescribedbelow.

Thepuppywillinvestigateanynewinanimateobjectinitspeninmuchthesameway,exceptthatnotailwaggingisinvolved.However,thepuppyisinnosenseahuntinganimalatthisage.Evenwhenraisedinourlargeone-acrefields,puppiesstayedwithin10to20feetoftheirnestboxuntilapproximately12weeksold,whentheybegantospreadoutandinvestigatetherestofthefield.

Agonisticbehavior.—Thefirstevidencesofagonisticbehaviorarethestartlereactionstosoundandsuddenmovement.Frombeingananimalwhichdoesnotrespondtothesestimuliatall,thepuppynowrespondstoallloudsoundsandsuddenmovementsindiscriminately.Itsnewcapacitiesforlearningsoonenable

suddenmovementsindiscriminately.Itsnewcapacitiesforlearningsoonenableittodiscriminatebetweenthosesituationswhichareactuallydangerousandthosewhichhavenosignificance;andasthepuppygrowsolder,itno

longerrespondstoirrelevantsoundsandmovements.Themotherstimulatesfearresponsesinweaningherpups,andtheycanoftenbeelicitedbyahumanhandlerwalkingrapidlytowardthepuppy,eventhoughithasneverbeensteppedupon.

Thedevelopmentofthesefearresponsesdependsagooddealupontheenvironmentofthepuppy.Underournormalmethodsofrearing,manypuppiesbecomequitefearfulofhumanhandlersat5weeksofage.Thisfearalmostcompletelydisappearedinreactiontodailyhandlingthroughoutthenexttwoweeks.However,whenpuppieswereraisedinlargefieldswithfewhumancontacts,thefearresponsesbecameprogressivelymoreextreme.InoneexperimentFreedman,King,andElliot(1961)broughtpuppiesinfromsuchafieldatdifferentagesandplacedtheminaroomwithapassiveobserverfor10minuteseachday.At3weeksofage,thepuppiescametotheobserveralmostatonce;butby7weeks,ittooktwodaysontheaveragebeforethepuppieswouldmakeapositivesocialapproach.The14-week-oldpuppiesweresofearfulthattheynevercamecloseevenafteraweek.Theselastpuppieswerelikelittlewildanimalsandcouldbetamedonlyinthewayinwhichwildanimalsareusuallytamed,bykeepingthemconfinedsothattheycouldnotrunawayandfeedingthemonlybyhand,sothattheywerecontinuallyforcedintoclosehumancontact.

Instillanothersituation(Fisher,1955;Fuller,Clark,andWaller,1960),inwhichpuppieswerekeptisolatedinindividualpens2feetsquare,activeescaperesponsesneverdeveloped.Whenbroughtfromhispenforthefirsttimeat16weeksofage,thepuppymightcrouchinacorneroradoptbizarrepostures,orevenshow"fearbiting,"buthedidnotrunaway.

Playfulfightingappearsearlyinthisperiod(seeFig.4.2).Atfirsttheyoungpuppiesseemtobeactinginslowmotion,clumsilypawingandmouthingtheirlittermateswithoutproducinganyrealdamage.Astheygrowoldertheirteethbecomelonger,andapuppywhichgetsholdofasensitivespot,suchastheear,maybeansweredbyayelpofpain.Oneindicationthatfightingisnotseriousatthisearlyagecomesfromthedominancetests.At5weeks,lessthanone-fourthofthepairsofpuppiesshowedcompletedominance.

However,atabout7weeksofage(thetimewhenfinalweaningfromthebreast

However,atabout7weeksofage(thetimewhenfinalweaningfromthebreastbeginsandmothersbegintothreatentheiroffspring),puppiesleftwiththeirmothersbegintoattackeachotheringroups.Theanimalagainstwhomtheattackisdirectedissometimesasmallandweakindividual,butitalsomaybealargeandaggressiveone.Inmostbreedsthis"gangingup"istemporaryandplayful.Inthe

BEHAVIORPATTERNS

foxterrierbreed,however,suchgroupattacksarepersistentandbecomesoseriousthatthevictimhastoberemovedinordertopreventseriousinjury(Fuller,1953).Inonelitterofsixanimalstherewerethreemalesandthreefemales.Thegroupbegan"gangingup"onthesmallestfemale.Whenshewasremovedtheybegantoattackanotherfemale,andwhenshewastakenouttheyattackedthethird.Thefinalresultwastwoseparategroupsofthree,sinceonefoxterriercanapparentlystandofftwobutnotthreeotheranimals.Inlargergroups,onepuppywouldgetholdoftheearsandanotherthetail,stretchingtheirvictimbetweenthem,whilethethirdanimalattackedinthemiddle.Notevenafoxterriercantakemuchofthis.

Inotherbreedsthegroupattackswereneverserious,andindividualfightsusuallyresultedintheformationofsomesortofdominancerelationshipwithouteitherindividualbeingseriouslyhurt.However,suchrelationshipsarenotoftencompletelyformeduntilthenextperiodofdevelopment.

Allelomimeticbehavior.—Atfirstthemembersofalitterarequiteindependentintheiractivities,wanderingoverthepenindifferentdirections.Between3and4weeksofagetheybegintofolloweachotheraround,andby5weeksweoftenseethepuppiesrushingtowardthegateoftheirpenasagroup(Table4.4).Thisisthefirstappearanceofthepackbehaviorofadults.By7weeksthepuppieshavebegunthegroupattacksdescribedabove,whichareacombinationofallelomimeticandagonisticbehavior.

TABLE4.4

TimeofDevelopmentofAllelomimeticBehaviorasIndicatedbyCo-ordinatedMovement

Total

160

160

50

Sexualbehavior.—Mountingandclaspingmayappearsometimesasearlyas3or4weeksofage.SupportingapuppybyahandthrustbetweentheForelegsandunderthebellywillsometimesstimulatethrustingmovements.However,thesexorgansthemselvesarestillundeveloped,andsuchbehaviorisnevercomplete.Asourpuppies


107

grewolderwesometimesobservedtheplayfulattitudewhichisthecharacteristicpartoftheadultcourtshippattern.

TABLE4.5

OccurrenceofSexualBehaviorin160PurebredPuppies(0-16WeeksofAge)duringDailyObservationPeriods

Notethatsexualbehaviorisseenslightlymoreofteninmalesthaninfemales,hencesomewhatearlier.Resultsintheindividualpurebreedswerehighlyvariable.

Otherpatternsofsocialbehavior.—Epimeleticbehaviorisneverseenexceptwhenthepuppiesscratchorlickthemselves.Unlikeprimates,dogsshowverylitttletendencytowardmutualgrooming,andtheonlysituationwhichstimulatesitisanopenwound.Thecapacityforsomeofthepatternsofmaternalcaremayexistinolderpuppies,butundernormalconditionsthenewbornpuppieswhichmightstimulatethesepatternsareneveravailable.Shelter-seekingbehaviorcontinuesbutislikelytobelessened.Thepupsmaysleepoutsidetheirnestboxesandsleepapartfromeachothermoreoftenastheperiodprogresses.

Changesinbasiccapacities.—Theretinaoftheeyeisnotcompletelyformeduntilabout4weeksofage;andtheEEG,indicatingthefunctionofthevisualportionofthecortexofthebrain,doesnotassumetheadultformuntil7or8weeksofage.Thismeansthatthepuppydoesnothavesensoryfunctionscompletelycomparabletothoseofanadultuntilseveralweeksafterthebeginningoftheperiodofsocialization.

Astomotorfunctions,thepuppyassumestheadultformsoflocomotionandchewingattheoutsetoftheperiodbutstillhasnotreachedanythinglikeadultcapacitiesbyitsend.A7-week-oldpuppyiseasytocatchevenwhenrunningattopspeed,anditcandoverylittledamagewithitsimmatureteethandjaws.Evenat12weeksapuppyisaclumsyrunnerwithlittleendurance.

Withregardtolearningcapacities,thepuppyhasattheoutsetoftheperiodtheabilitytomakerapidassociationsbetweenstimuli,andinthisrespectitissimilartoanadult.However,itsmotorresponsesarestillnotcompletelydeveloped,andthismeansthatwhilethepuppymaylearnagreatdealfromtheoutsideworld,itisstill

notcapableoflearningcomplicatedmotoractswhichrequirespeedandgoodmuscularcontrol.

Conclusion.—Duringtheperiodofsocializationthepuppybeginstoshowmostoftheadultpatternsofbehavioratleastinaplayfulform.Ingestivebehavior,whichwasmostimportantintheneonatalperiod,isnowreduced,andthemostprominentaspectofbehaviorissocialplay.Thisisthetimeduringwhichsocialrelationshipsareeasilydeveloped,eitherwithotherpuppiesorwithhumanbeings.Thebehaviorwhichinitiatestheserelationshipsissocialinvestigation,followedbyplayfulfightingandsexualbehavior,bothinvolvingbodilycontact.Theserelationshipscanbedevelopedwithanyindividualwhostayswiththepuppies.Atthesametimeweseetheappearanceofbehaviorwhichlimitstheformationofrelationshipswithcasualstrangers.Thefirstreactiontoastrangerisoneoffear.Asapuppybecomesolder,fearandescapereactionsbecomestrongerandmoredifficulttoovercome,sothatacasualstrangernevermakescontact.

Thisis,therefore,acriticalperiodfortheformationofsocialrelationships.Weshallexaminethisconceptmorecarefullyinpages110-12.

JUVENILEPERIOD

Thisperiodbeginswiththefirstlongexcursionawayfromthedenornestboxandendsatsexualmaturity.Thusitrunsfromapproximately12weeksofageupto6monthsorlater.Thechangesarenotasstrikingasbeforeandwillnotbetreatedingreatdetail.

Changesinbasiccapacities.—Allthesenseorgansappeartobefullydevelopedattheoutsetofthejuvenileperiod.Permanentteethbegintocomeinatabout16

attheoutsetofthejuvenileperiod.Permanentteethbegintocomeinatabout16weeksofage,andallareusuallypresentby6months.Growthcurvesalsobegintoflattenoutat16weeks.Theperiodofrapidgrowthisover,andthepuppyisapproximatelytwo-thirdsofitsadultsize.

Thedevelopmentofmotorcapacitiesinthisperiodconsistsofincreasesinstrengthandskillratherthantheemergenceofnewpatterns.Muchdependsontheenvironment.Puppiesraisedinopenfieldsaremoreactiveandskillfulthanthoseraisedinkennels,althoughanypuppyat4monthsisstillanawkwardandganglingannual.By6monthsthemostadvancedpupsareverysimilartoadultsinsizeandmotorcapacities.Inawildspecies,wewouldjudgethemtobecapableofexistingindependentlyfromtheirpar-

DEVELOPMENTOPBEHAVIOR109

ents.Theycontinuetogrowslowlythereafterandusuallyreachcompletephysicaldeyelopmentabouttheageoftwoyears.

Astobasiclearningcapacitiesthepuppyappearstobefullydevelopedbeforetheoutsetofthejuvenileperiod.Atabout4monthsofagethespeedofformationofconditionedreflexesbeginstoslowdown.Thisisprobablynotbecausethenervoussystemdeterioratesbutratherbecausewhatthepuppyhaspreviouslylearnedbeginstointerferewithnewlearning.Aswillbeseenlater,thereissomeevidencethatthebehaviorofthepuppybeginstoreachastableorganizationaboutthisage;thatis,hehasestablishedthefoundationforwhathewilllearninthefuture.Ontheotherhand,puppiesstillcannotbetrainedindifficulttasks,partlybecauseofpoormotorskillandpartlybecauseofashortattentionspanandreadyemotionalexcitability.

Changesinsocialbcliaviorpatterns.—Puppiesraisedinalargefieldfirstbegantomoveawayfromthenestareaandexplorethesurroundingenvironmentatabout12weeksofage.Thisprobablyrepresentsthebeginningofthepatternsofhuntingbehavior.Wealsohavesomeevidencethatpuppiesmakeatransitionfromonephysicalenvironmenttoanothermoreeasilyatthisstagethananyother.Distressvocalizationinresponsetoachangedenvironmentreachesalowlevelat12weeks(ElliotandScott,1961).Guidedogpuppiesusuallymakeasuccessfuladaptationwhenplacedinhomesat12weeks,butthosekeptinakennellongerthan14weeksshowincreasinglypoorperformanceduringtheirlatertraining(Pfaffen-bergerandScott,1959).

Themalepatternofeliminativebehaviorappearssometimeduringthisperiod,varyingconsiderablyaccordingtothespeedofdevelopmentoftheanimals.Indogsraisedoutsideakennel,Martins(1947)foundthatthisfirstoccurredbetween5and8months.Thisincludestheleg-liftingreactionatscentpostsandscratchingafterdefecation.

Agonisticbehaviorhasdevelopedintoadefinitedominance-subordinationpatternby15weeks,andthepuppiesconcernedshowthepatternsofbehaviortypicalofadults.Thismeansthattheoccurrenceofactualfightingismuchreduced,althoughthegrowlsandyelpsofthreatandsubordinationreactionsmayfrequentlybeheardinalitterraisedtogether.

Thedominanceorderalsolimitscontactwithstrangeanimals,asthepuppiestendtoattackstrangersplacedwiththem.Thedegreeoftolerancetowardstrangersdependsuponthebreedaswellasthestateofdevelopment.Tinbergen(1958)observedthatpuppies

growingupinanEskimovillagebegantodefendterritoriesatthetimeofsexualmaturity,whichwouldbeattheendofthejuvenileperiod.

Allelomimeticbehaviorbecomesmoreandmorecommon,thelittertendingtoreactasagroupinmanysituations.Whenoneanimalmovestoinvestigateanoiseormovement,therestusuallyfollow.Playfulsexualbehaviorcontinues,buttheanimalsareusuallydistractedfromthisbyanvothersortofstimulation.Suchincompletesexualbehaviorisnotusuallyseenunlesstheanimalsarecompletelyunawareoftheobserver.Thisisverydifferentfromtheconcentratedattentiononsexualbehaviorseeninadults.Estrusofthefemalesandtheemergenceofthecompletepatternofadultsexualbehaviorbybothsexesmarkstheendofthejuvenileperiod.

Conclusion.—Comparedtothepreviousperiod,thejuvenileperiodisoneofgradualchange,chieflvinvolvingthematuringofmotorcapacities.Itendswiththematurationofsexualcapacitiesandtheconsequentabilitytoformcompletesexualrelationships.

Behavioraldevelopmentcontinuesthroughoutlife.Thenextimportantchangesfollowthebirthofpupsandincludetheoriginsofepimeleticbehavior.Thisbehaviorenablesthedevelopmentofthemother-offspringsocialrelationship.Alongandstableperiodofmaturityfollows,endingwiththecessationofreproductiveactivity.Thisoccursabouttheageof8inmostfemalesand

reproductiveactivity.Thisoccursabouttheageof8inmostfemalesandconsiderablylaterinmales.Manydogsbegintoshowadeclineoffertilityandphysicalvigoraftertheageof5,althoughtheyfrequentlylivetothreetimesthisage.

CRITICALPERIODSINDEVELOPMENT

Wehavedividedthedevelopmentofthepuppvintoperiodsbasedonmajorchangesinsocialrelationships.Immediatelyafterbirththepuppyestablishesthenursingrelationshipwithitsmother,markingthebeginningoftheneonatalperiod.Thetransitionperiodconsistsofrapidchangesinthisrelationship.Atitsend,thepuppyiscapableofforminganewtypeofsocialrelationshipwhichwillpersistintoadultlife.Atthispointthemotherceasesherconstantcareofthepuppies,sothatthestrongestrelationshipstendtobeformedwiththelittermatesratherthanwiththemother.Theserelationshipsformthefoundationofthetypicalsocialgroupofadults,thepack.Therelationshipwiththemotherisstillfurtherweakenedwhenfinalweaningfromthebreastoccurs,althoughinwildCanidaetheparentscontinuetofeedthevonngforsomemonthsbyvomitingor

bybringingthemmeat.Theolderanimals,neverthelessmayspendonlyafewminutesoutoftheentiredayincompanywiththeirpups,spendingtherestofthetimehunting.Thenextmajorchangeoccurswiththeformationofsexualrelationshipsasthepuppiesbecomeadults.

Thesefactssuggestamajorhypothesis:thattheperiodatwhicheachnewrelationshipisformedisacriticalonefordeterminingboththenatureoftherelationshipandtheidentityoftheindividualswithwhichtherelationshipisformed.Forexample,theneonatalperiodiscritical,forunlessthepuppynursessuccessfully,itwilldie.Theperiodofsocializationiscritical,sinceitdetermineswhatspeciesandindividualswillbecomethechiefadultrelativesofthepuppy.Apuppytakenfromitslitterearlyindevelopmentandraisedbyhandwillformitsparamountrelationshipswithpeople,becomingan"almosthuman"dogandpayinglittleattentiontoitsownkind.Removedalittlelaterintheperiod,itformsstrongrelationshipswithbothdogsandhumanbeings.Stilllaterithasalreadyformedstrongrelationshipswithdogsanditstieswithhumanbeingstendtoberelativelyweak.

Thisisthemostimportantcriticalperiodinthelifeoftheanimal.Inadditiontothedeterminationofsocialrelationships,theemotionalsensitivityandstillundevelopedmotorandintellectualcapacitiesofthepuppysuggestthatthismayalsobeacriticalperiodforpossiblepsychologicaldamage.Emotionalsensitivity

alsobeacriticalperiodforpossiblepsychologicaldamage.Emotionalsensitivityisapparentlyanecessarypartofthesocializationprocess,andthisautomaticallymakestheanimalsusceptibletopsychologicaldamageaswell.

Stillanothercriticalperiodbeginswithsexualmaturity,whenthematingrelationshipisdetermined,alongwithpoororgoodadjustmentinsexualbehavior.Bothoftheseadjustmentsmaybegreatlyinfluencedbywhathasalreadyhappened,particularlyintheperiodofsocialization.

Wehavedefinedthedividinglinesbetweenperiodsasmajorchangesinsocialrelationships.Theperiodsthemselvesarecharacterizedbycertainprocesses.Thatintheneonatalperiodistheprocessofneonatalnutrition,ornursing.Thesameprocessgoesoninthetransitionperiod,butthereisalsoanewmajorprocessgoingon,thistimeabiologicalone.Thegreatestmaturationalchangesinbasiccapacitiestakeplaceinthetransitionperiod.Atitsendthepuppycanmoveindependentlyofitsmotherandalsobegintotakesolidfood.Furthermaturationalchangescontinuetotakeplace,butnothingassuddenanddrasticasthese.

Themajorprocessofthenextperiodisthatofsocialization,the

112BEHAVIORPATTERNS

formationoflastingsocialrelationships.Thisagainisanongoingprocesswhichprobablyneverstopsentirelyinthelifeoftheanimal,buttheperiodofsocializationisthepointatwhichthebiggestchangesoccurandalsothetimewhenitiseasiesttoinitiatesuchrelationships.

Anothermajorprocesswhichtakesplaceduringthisperiodofdevelopmentisthatoflocalization,inthesenseofaprocesscomparabletosocialization.Thepuppybecomesstronglyattachedtoaplaceandisseriouslyupsetifheismovedawayfromit.Ourdatashowthatthisprocessreachesitspeakat6to7weeksofagebutthattheemotionalresponsestobeingmovedcontinueforsometime.

Theresultsofsocializationandlocalizationaresosimilarthatwewonderwhethertheymayrepresentthesameprocessappliedtodifferentobjects.Thiswouldmeanthatthepuppybecomesattachedtoboththelivingandnon-livingpartsofitsenvironmentatthisage.

SUMMARYANDCONCLUSION

Apuppycomesintotheworldwithitsbehaviororganizedforlifeintheneonatalperiod,centeringaroundthefunctionofobtainingnourishmentfromthemother.Itishighlyprotectedfromoutsidepsychologicalstimulationbothbvmaternalcareanditsownimmaturity.Theneonatalpuppyisblindanddeaf,anditisdoubtfulifeventheolfactorysenseisdeveloped.Itsmotorcapacitiesaresolimitedthatitcanmoveonlywithinaradiusofafewfeet.Itscapacitiesforlearningarehighlylimitedcomparedwiththoseofolderpuppies,anditshowsalimitednumberofemotionalreactions.

Between2and3weeksofageaprofoundreorganizationofbehavioralcapacitiesoccurs.By3weeks,thepuppyisabletomoveandeatbyadultmethods.Allsenseorgansarefunctional,anditiscapableofmakingquickandeasvassociationsbetweenoutsideevents.Manyofthepatternsofadultsocialbehaviorandtheiraccompanyingemotionsappearatthesametime.Theacquisitionofthesecapacitiesisfollowedbvarapidorganization,throughlearning,ofbehaviorinrelationtootheranimals,people,andplaces.Whateverhappensheresetsageneralpatternwhichwillaffectalmosteverythinginlaterlife,becausebytheendoftheperiodthepuppyhasformedpatternsofrespondingtothemajorinfluencesinanysortoffutureexistence.Therewillbeotherperiodsofrapidorganizationofbehaviorinlaterlife,atthetimeofsexualmaturityandbirthoftheyoung,buttheireffectswillbemorelimited.

\>researchworkers,wecanconcludethatthepuppyisinmany

waysanidealanimalforstudyingtheeffectsofearlyexperience.Theperiodsofdevelopmentaresowelldividedandeasilyrecognizedthatitshouldbepossibletogivepuppiesthesameexperienceatdifferentagesandcometodefiniteconclusionsregardingtherelationshipbetweenexperienceandmaturation.Puppydevelopmentisahappycompromisebetweenextremelyshortdevelopment,whichpermitsverylittleeffectofexperience,andextremelylongdevelopment,whichmayrequirealifetimetoanalyze.

Thesestudiesonthedevelopmentofbehaviorleadtotwogeneralprinciplesregardingouroriginalproblemoftheeffectofheredityuponbehavior.Oneoftheseisthatgeneticdifferencesinbehaviormustbeproducedthroughdevelopmentalprocesses.Wecannotthinkofbehaviorasbeingsomethingrelativelyfixedandunchangedsuchashaircolor,butrathersomethingwhichisrapidlydevelopingandchangingthroughoutearlylifeandwhichcontinuestochangeastheanimalgrowsolder.

Hereditaryfactorsmustthenactbyaffectingdevelopmentalprocesses,suchasthegrowthanddifferentiationofsenseorgansandorgansystems.Hereditymayalsoaffectongoingphysiologicalprocessesthroughoutlife,oneofwhichistheprocessoflearningitself.Thisinturnisthebasisforothermajorprocesses:thefoundationofsocialrelationshipsandrelationshipswiththeinanimateenvironment.

Asecondprincipleisthatthemajorityofhereditarydifferencesinbehaviorareexpressedascomponentsofsocialrelationships,eitherwithotherdogsorwithpeople.Evenwhenadogiscompletelyalone,hemayreacttotheabsenceofothers,andinfactusuallydoesso,showingeveryevidenceofemotionaldistress.Thiscomplicatestheproblemofmeasurementofhereditarydifferences,becauseanysocialrelationshipisaninteractionbetweentwoindividuals,andisthereforeaffectedbytheheredityofboth.However,itisjusttheserelationshipswhichcharacterizetheorganizationofadultbehaviorandformwhatweordinarilycallindividualityorpersonalityinahumanbeing.

HUMANCOMPARISONSANDAPPLICATIONS

Whenwetrytocomparethedevelopmentofapuppywithahumaninfant(Scott,1963a),wefindthatmuchoftheinformationwhichwewouldliketohaveismissing.Childpsychologistshavegenerallystudiedchildreninschools,wheretheyareeasytogetat,andveryseldominhomes,wheretheirmostbasicsocialrelationships

BEHAVIORPATTERNS

areformed.Thismeansthat,inspiteofitstheoreticalimportancetolaterbehavior,thestudyoftheperiodofearlyinfancyhasbeenrelativelyneglected.

TABLE4.6NaturalPeriodsofDevelopmentinDogandMan

Dog

Man

Wedoknowenoughtomakeatleastsomegeneralcomparisons.Likethatofthenewbornpuppy,thebehavioroftheneonatalinfantisprimarilyconcernedwithneonatalnutrition.Theinfanthasbetterdevelopedsenseorgansandrespondstobothsoundandlight.However,visionofthehumanneonateisnotperfectlydeveloped,astheEEGreachesitsadultformatabout8yearsinsteadof8weeks

developed,astheEEGreachesitsadultformatabout8yearsinsteadof8weeksasinthepuppy.

Inmotorcapacitiesahumanneonateislessdevelopedthanthepuppy,notevenbeingabletocrawl.Itsmajortransitiontotheseadultcapacitiescomesbetweenapproximately7and14months,beginningwhenthebabydevelopsitsfirstteethandbeginstocrawl,

andisendingwhenitislaterabletowalk.Inthisrespectthe14-month-oldbabyisquitesimilartothepuppyofthreeweeks.

Herewecometoamajordifference.Whilethecapacityforsocialresponsivenessinthepuppydevelopsafteritstransitiontotheadultformoflocomotion,thebabydevelopsthecapacityforrapidconditioningbyoneortwomonthsandbeginstosmileinresponsetosocialstimulationlongbeforeitsgeneralmotorcapacitiesdevelop.From2until6months,thebabyrespondsindiscriminatelytoallhumanfacesbutbytheendofthistimeisbeginningtodevelopfearresponsestostrangersandby8monthsofageshowswhatisoftencalled"8-monthsanxiety."Itisonlvthenthattheaveragebabybeginstocrawlanddevelopitsothermotorcapacities.

Thus,theperiodofhumanprimarysocializationprecedesthedevelopmentoftheadultcapacitiesoflocomotioninsteadoffollowingthem,asinthepuppy.Thismeansthatthebabydevelopsitsstrongestrelationshipswiththepersonorpersonswhotakecareofitatthistime,usuallythemother,butalsothefatherandsiblings.Thisalsoproducesanemphasisonthedevelopmentofstrongrelationshipsbetweenolderandyoungerindividualsratherthanthecanineemphasisonstrongrelationshipsbetweencontemporaries.

Wecanalsoseethatindifferentspeciesofmammalsdifferencesarenotsimplyamatteroflongerorshorterdevelopment;theorderofcertainmajordevelopmentalchangesisactuallyreversedinthetwospecieswehavecompared.This,ofcourse,raisesthequestionofhowmuchvariationofthissortcantakeplacewithinaswellasbetweenspecies.

Thesimilaritiesbetweenhumanandpuppydevelopmentsuggesttheexistenceofacriticalperiodforprimaryhumansocializationhavinggreatpracticalsignificancefortheproblemsproducedbythelossofparentalcareandchangesproducedbyadoption.Whiletheevidenceissomewhatunclearduetotheundesirabilityofmakingdeliberateexperimentswithsuchseriousconsequencesonhumanbeings,alloftheevidenceindicatesthatsuchaperiodexistssometime

onhumanbeings,alloftheevidenceindicatesthatsuchaperiodexistssometimeduringthefirstyear.

Thisconclusionisbolsteredbytheevidencefromotherspeciesofanimals.Everyhighlysocialspeciesofanimalwhichhasbeenstudiedsofarhasashortperiodearlyinlifewhenprimarysocialrelationshipsareformed.Inbirds,withtheirveryshortperiodsofdevelopment(asongsparrowprogressesfromhatchingtoadultflyingin4weeks),theprocessofsocializationtakesplaceextremelyrapidlyandsohasreceivedthename"imprinting."Inthebird,thecriticalperiodforsocializationmaybeamatterofafewdaysorevenhours;

116BEHAVIORPATTERNS

inthepuppyamatterofweeks;andinthehumaninfantamatterofmonths.Theselongerperiodspermitthedevelopmentofawiderandlessspecificsetofrelationships,butthebasicphenomenonappearstobethesame.

Whenwerealizedthetheoreticalandpracticalimportanceofthesediscoveries,wedidtwothings.Onewastocalltheseresultstotheattentionofaconferenceofscientistsinterestedincomparinghumanandanimalbehavior.(Scott,1952).Werealizedthatsuchageneralprincipleasthatofcriticalperiodscouldbeestablishedonlythroughtheco-operationofmanydifferentscientistsandinstitutionsworkingonmanydifferentspeciesofanimals,andcomparingtheresultswithobservationsonchildren.Theotherwastoinstitutearesearchprogramatourownlaboratory,inordertoverifytheobservationswehavedescribedinthischapterthroughexperimentalmeans,andalsotodiscoverthephysiologicalandpsychologicalcausesofthesephenomena.Theresultsofthisprogramaredescribedinthenextchapter.

THECRITICALPERIOD

Aswehaveseenintheprecedingchapter,ourstudiesofthedevelopmentofbehaviorshowthatapuppyentersintoaperiodofgreatchangeandsensitivitywithregardtosocialrelationshipsatapproximately3weeksofage,andthathisexperiencesatthistimedeterminewhichanimalsandhumanbeingswillbecomehisclosestsocialrelatives.Thisisatimeofmajordecisionaffectingalltherestofhislife,andtheperiodisthereforeacriticalone.

Inordertotranslatethisintoaworkablescientifictheory,wemustsharpenuptheconceptofcriticalperiods.Byacriticalperiod,wemeanaspecialtimeinlifewhenasmallamountofexperiencewillproduceagreateffectonlaterbehavior.

whenasmallamountofexperiencewillproduceagreateffectonlaterbehavior.Todrawananalogy,itisagreatdeallikepullingthetriggeronahigh-poweredrifle.Averysmallamountofeffortcausesthebullettotravelathighspeedandproduceasmashingimpactatagreatdistance.

Thisisthekindofscientificdiscoverywhichcanhaveimmensepracticalvalueifitturnsouttobecorrect.Agreatpartofscientificeffortisdirectedtowarddiscoveringpreciselythissortofcausalrelationships.Itisnotenoughtoknowacause,foriftheeffortrequiredtomanipulateitisequaltoorgreaterthanitsresult,thediscoveryhasonlylimitedusefulness.

Goingbacktotheideaofthecriticalperiod,wecanseethatitisarelativeratherthananabsoluteconcept.Thedifferencebetweentheamountofeffortneededtoproducethesameeffectatdifferentperiodsdeterminesjusthowcriticaltheperiodis.Inthecaseofthepuppy,itlooksasifasmallamountofcontactshortlyafter3weeksofagewillproduceastrongsocialrelationshipwhichcanbeduplicatedonlybyhoursorweeksofpatienteffortatlaterperiodsinlife—if,indeed,itcanbeduplicatedatall.

117

118BEHAVIORPATTERNS

Itmightbesupposedthattheeffectofthissortofcontactisinverselyproportionaltoage,i.e.,theyoungertheanimalthegreatertheeffect.Ifthisweresowecouldnotproperlyspeakofacriticalperiod.Inordertodefineaperiodtheremustbedefiniteandimportantchangesboundingitsbeginningandend.Oneimportantscientificproblemisdeterminingthenatureoftheselimits,forthisinformationmayinturnleadtothediscoveryofhowtomodifyorprolongtheperiod.

Theremaybemorethanonecriticalperiodinthelifeofanindividual.Theperiodwehavedescribedinthepuppyisacriticaloneforthedeterminationofprimarysocialrelationships,butthisneednotbetheonlyone.Therecouldbeavarietyofcriticalperiodsindevelopmentfordifferentevents.Forexample,wehavestatedthehypothesisthatthetimeinwhichanyimportantsocialrelationshipisbegunisacriticalonefordeterminingthenatureofthatrelationship.Thetimesofthefirstmatingandthebirthofoffspringshouldalsobecriticalperiodsfortheformationofsexualandparent-offspringrelationships.

Ontheotherhand,differentsortsofcriticalperiodsmightcoincide.The

Ontheotherhand,differentsortsofcriticalperiodsmightcoincide.Theemotionalsensitivityofthepuppyduringtheperiodofsocializationsuggeststhatthisperiodmightalsobeacriticaloneforpermanentpsychologicaldamage.Ifthenatureandimportanceofcriticalperiodscanbeestablishedfirstinanimalsandeventuallyinhumandevelopment,theconcepthasimmensepracticalpossibilitiesfortheimprovementofmentalhealth.Ifweknewthatarelativelysmallamountofeffortattherighttimeindevelopmentwouldstartachildtowardbeingabasicallyhappyandproductiveindividual,wecouldmakevaststridesintheimprovementinhumanbehaviorwithinageneration.Atthepresenttimeweknowthatdisorganizedfamilyconditionsappeartohaveabadeffectonyoungchildren.Ifthecritical-periodhypothesisturnsouttobecorrect,wecaninthefuturesaytoaparent:"Ifyoudothusandsoataparticulartime,youwillbemorelikelytohaveawell-adjustedchildthanifvoudoitatanearlierorlatertime."Meanwhile,wecangetsomeideaoftheneedfulscientificinformationfromourstudiesonthedog.

BOUNDARIESOFTHECRITICALPERIOD

Aswehaveseenintheprecedingchapter,itiseasytoestablishabeginningpointforthecriticalperiodofprimarysocializationinthepuppy.Betweenând3weeksofageaverylargenumberofchangestakeplaceinrapidsuccession,andallofthesemodifythecapacity

THECRITICALPERIOD119

forformingaclosesocialrelationship.Theperiodofchangeortransitionbeginswiththeopeningoftheeyesandincludestheopeningoftheearsandthestartleresponsetosound.Atitsendthepuppyiscapableofwalking,sothatitcaneitherapproachoravoidanotherindividual.Itbeginstoeatsolidfoodandhencestartstobeindependentofthemother.Itdevelopstheabilitytomakerapidassociationsbetweenoutsideeventsandunpleasantfeelings.Thislastchangeisprobablythemostimportantonewithregardtoestablishingaboundaryforthecriticalperiodforformingprimarysocialrelationships,becausethepuppyisnowcapableofdiscriminatingbetweenindividuals.Thiscapacityisdifficulttodeterminebyobservationandcanbemeasuredaccuratelyonlybyaseriesofelaborateexperiments.Fortunatelythereisachangeinbehaviorwhichseemstobecloselycorrelatedwithit,andwhichiseasytodetermine—theappearanceofthestartleresponsetosound.Wecanarbitrarilyusethisasamarkertoindicatethebeginningofthecriticalperiod.

Howisthisdevelopmentalchangerelatedtoage?Wecanrecordthedateon

Howisthisdevelopmentalchangerelatedtoage?Wecanrecordthedateonwhichthestartleresponseoccursandcalculatetheageofeachanimal.Therewillobviouslybesomevariationinage,reflectingdifferencesinthestateofdevelopment,andoneimportantpracticalproblemisthatofdeterminingtheextentofthisvariationinnormaldogpopulations.

Normalvariationindevelopment.—Inthefirstplacethereisvariationintherateofprenataldevelopment.Theaveragegestationperiodofthedogisusuallyreckonedat9weeks,or63daysaftertheonsetofreceptivity.Thisitselfisonlyanestimate,becauseovulationtakesplaceapproximately72hoursbeforetheendofreceptivity,andthetotallengthoftheperiodofreceptivityvariesagreatdealindifferentanimals.Embryonicdevelopmentinthedogisunusualinmanyrespectswhicharecorrelatedwithitslifeasahuntinganimal.Thefertilizedeggdevelopsveryslowlyanddoesnotbecomeimplantedintheuterusfor3weeks.Evenafterthis,itbeginsrapiddevelopmentonlywhentheplacentahasbeenestablished.Thismeansthattheembryogrowsveryslowlyatfirstandveryrapidlyinthelast4or5weeksofpregnancy,sothatthebitchhasarelativelyshortperiodwhensheisheavyandincapacitatedforactivelife.Boththetimeinwhichtheeggsbecomeimplantedandtheirpositionintheuteruscouldproducevariationinthestateofdevelopment.Wehavenoevidenceonthedog,butstudiesontheembryologyoftheguineapigshowthatembryosofthesamechronologicalagefromconceptioncanvaryatleastadayortwoinstateofdevelopmentwithoutanyobvioussignofabnormality(Scott,1937).Morethanthis,

thereissomevariationinthetimesatwhichpuppiesareborn,somelittersbeingobviouslymorematureatbirththanothers.Thisprobablyaddsatleastanotherdayortwoofdevelopmentalvariation.Finallv,thereistheaccuraevofthemeasurementofa°;eitself.Whenwerecordedtwolittersasbornonthesamedate,theyactuallycouldhavebeenborn24hoursapart,sincenoobservationsweremadeatnight.Allthiswouldadduptoarangeof5or6days'variationindevelopmentforanimalsrecordedashavingbeenbornonthesamedaytodifferentmothers.

Letusnowlookattheactualfigures.Weexaminedandtestedthedogsonceperweekinordertoavoidexcessivehandlingintheearlystagesofdevelopment.Hencewemustestimatevariationonthebasisoftheseweeklyfiguresratherthanondailyones.Thefirstchangeistheopeningoftheeves(Table5.1).Outof195purebred

TABLE5.1

EstimatedVariationinDevil:?v:i:-"iaxEventsAssociatedwiththeBeg::-ofthePeriodsofTransitionandSocializationinPurebredPuppies

EyescompletelyopenITransitionperiod15.0

startletosound\Socializationperiod19.51:

FirstteetheruptedSocializationperiod-v2.9

puppies,onlyonecockerspanielhaditsevescompletelvopenatoneweekofage.Therearelars;edifferencesindevelopmentbetweenthedifferentbreeds,butweightingthebreedsequallywefindthat59percenthavetheeyescompletelvopenat2weeksand100percentat3weeks.Assumingthatthetimeofopeningtheevesisdistributedinanormalcurve,wecanestimatethattheaveragetimeforthiseventis13dayswithastandarddeviationof2.3days.Thestandarddeviationmeasuresthepointofinflexionofthenormalcurve,andthismeansthattwo-thirdsofthepuppieswouldopentheireyesbetween10.7and15.3days.One-sixthofthemmightopentheireyessoonerandone-sixthlater.Thisresultfitsvervwellwithourtheoreticalexpectationthatwhiletheaveragemightfallonaparticularwemightexpectarangeofvariationofapproximatedaweekinthesedevelopmentale\\Qts5kott,195s

Amoreimportanteventformarkingthecriticalperiodisthedate

onwhichtheanimalsgivethestartleresponsetosound.Twoani-

>r1pctionat14days,and74percentat

3weeks.Theestimatedaveragewouldbe19.5dawswithastandard

deviationof2.3days.Again,thiswouldmeanthatone-sixthofthe


animalsshouldshowthisresponsebefore17.2daysandone-sixth(theslowdevelopers)after21.8days.

Thesefiguresareimportanttorememberininterpretinganyexperimentalresults.Ofanimalsgivenexperimentaltreatmentbetween14and21daysofage,three-quartersofthemwouldhavepassedintothecriticalperiodsometimeduringtheweek,andonlyaboutoneinahundredmighthavespenttheentireweekinthisperiod.Wewouldthereforeexpecttheexperimentalresultsfromthisperiodtobequitevariable.

60-

k-I->(-lL-k-HI,SOCIALIZATION>k—XZ,JUVENILE^

*>EYESOPENÂDULTEEG

/z-CONDITIONINGV^MOTHEROUT

/BEGINS/

8ea*--"J..

Fig.5.1.—Developmentoftheheartrate.Notethatallbreedsshowadepressionoftheheartrateduringtheearlypartoftheperiodofsocialization.

oftheheartrateduringtheearlypartoftheperiodofsocialization.

Wecannowattempttodefinetheendofthecriticalperiod.Thisisnotaseasytodo,andourmeasurementsaremuchlessexact.Thedataonthedevelopmentofthebrainwaves(basedonasampleofonly10puppies)indicatesthatthematureconditionisreachedsometimebetween7and8weeks(CharlesandFuller,1956).Mothersbegintocompletelyweantheirpuppiesfromthebreastatabout7weeksofage.Theymayormaynotbeinfluencedbythedevelopmentofthepups,butweaningdoesindicateachangeinsocialrelationships.Ourmeasurementsoffearfulreactionstohumanhandlingindicatethatthemaximumreductionofthisbehavioroccursbefore7weeksofage(Fig.5.7).However,ourbestobjectiveevi-

22BEHAVIORPATTERNS

denceofchangeatthistimecomesfromthemeasurementofheartrates.AscanbeseeninFigure5.1,allbreedsshowareductionintheheartratebetween1and3weeksofage,andintwoofthebreedsthischangebeginsbetween1and2weeks.Alowpointoccursat3and4weeks,thisbeingextendedto5weeksinthebasenji.Ahighpointisreachedagainat6weeksinthreeofthebreeds,7weeksinanother,and8weeksinanother.Thischangeinheartratemayreflecteitherachangeintheabilityofthisresponsetobeconditioned,thusbringingitundertheadulttypeofemotionalcontrol,oritmaysimplyreflectachangeintheemotionalresponsestothehandlers.Atanyrate,itisthemostobjectivemeasureofdevelopmentalchangewhichwehaveavailable,anditledustoestimatethattheendofthecriticalperiodoccurredatapproximately7weeks.

Wehaveonemorepieceofconfirmingevidence:thevocalreactionofagroupof32beaglepuppiestoisolationinastrangeroomatdifferentages.Themaximumvocalizationwaselicitedbetween6and7weeks,witharapiddecreasethereafter.Allthesedataindicatethatimportantdevelopmentalchangestakeplaceat7weeksofageorshortlythereafter,andwetentativelysettheendofthecriticalperiodatthisage.Thisdatecanbedecreasedorincreasedbyindividualvariabilityofatleastaweek,sinceotherdataindicatesthatindividualvariabilityincreaseswithage.Asfurtherexperimentalworkshows,thisestimatewasactuallytooearlybyseveralweeks.

Developingatechniquefortestingthecriticalperiodhypothesis.—Ahealthylitterof6beaglepuppieswasbeingraisedinthenormaltestingprograminthe"SchoolforDogs"whenDr.EmilFredericsonjoinedourstaff.Heperformedapilotexperimentontheseanimalsbytakingthemawayfromthemotherand

pilotexperimentontheseanimalsbytakingthemawayfromthemotherandlittermatesatdifferentagesandgivingthemclosecontactwithhumanbeings(Scott,Fuller,andFredericson,1951).Thefirstpuppywastakenatbirthandraisedonabottleuntil2weeksofage.Asidefromdifficultiesingettingittonurse,itshowednobehavioraldisturbance,althoughitwasnotaswellnourishedasitslittermates.Thesecondpuppywastakenawaybetween2and4weeksofage.Itreadilyadjustedtothenursingbottleandshowednodisturbanceofbehavioreitherwhentakenawayorwhenreturned.Accordingtoourtheoreticalcalculations,thisexperiencewithpeopleincludedaweekormoreoftheearlypartofthecriticalperiod.Thethirdpuppy,removedfromthemotherat4weeksofage,showedexcessiveemotionaldisturbanceandatonepointyelpedcontinuouslyfor24hours.However,itsoonbecameadjustedtothefamilyandhomeinwhichitwaskeptandbegantoaetlikeapetdog.Thefinalexperimentalpuppywastaken

THECRITICALPERIOD

123

awayfrom6to8weeksofage.Becausethecriesofthepreviouspuppyhadupsetthehumanfamily,thispuppywaskeptatthelaboratoryandgivenextensivecontactwithpeopleonlyduringofficehours.Itshowedthesamesortofemotionaldisturbanceasthepreviouspuppv,butnotsointensely.Theremainingtwoanimalswereleftwiththemotheratalltimesandusedascontrols.

Afterthisexperience,allthepuppieswereputbackwiththemotherandlittermatesandgiventheregulartestingroutine.Withinaveryshorttimethebehaviorofonewasindistinguishablefromanother.Inthissituationanyeffectsoftheirearlyexperiencewerenogreaterthanthenormalvariabilityinthelitter.

Wenowattemptedtofindoutwhethertheearlyexperiencehadsomelessobviouseffect,andwetriedtoduplicatetheoriginalexperiencebytakingeachanimaltoastrangeprivatehomeandkeepingitovernight.Table5.2showsthegeneralresults.Initsover-all

TABLE5.2RelativeAdjustmentofPuppiesat1YearofAge

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score,theanimalwhichhadbeenremovedbetween4and6weeksmadethequickestandbestadjustmenttothesituation,confirmingourexpectationregardingtheextentofthecriticalperiod.Ontheotherhand,oneofthecontrolsdidalmostaswell,andweconcludedthattheexperienceofsocializationintheordinarylaboratoryconditionswassufficienttoproducealmostasgreataneffectonsomeanimalsasdidtheintensivehometreatment.Oneofus(Fuller,1961)hassincefoundthatsemi-isolatedpuppiescanbesuccessfullysocializedwithaslittlehumancontactastwo20-minuteperiodsperweek.Wethereforebegantolookforanothertechniquewhichwouldproducemaximumdifferences.

Inthepreviouschapterwehavedescribedtheresultsofobservingdogslivinginlargefieldsapartfromhumanbeings.Theexperimentincludedraisingpuppiesinthesamefields,andoneobviousresult

124BEHAVIORPATTERNS

wasthatthesepuppiesbecameextremelywild.Wetookonehomeattheageof12weeksandattemptedtomakeapetoutofit.Itwasextremelyfearfulatfirst,butbyconfinementandhandfeedingweeventuallycalmeditdownandgotittoacceptclosecontactswithpeople.However,itwasalwavsdifficulttocontrolandtimidwithstrangers,andwhenevertherewasachoicebetweenhumananddogcontactsitchosethedog.Itlookedasifrearinginlargefieldsproducedthemaximumeffectforwhichwewerelooking.Beaglesandfoxterriersbecameequallywild,theonlydifferencebeingthatthelattercouldnotbetrustednottokilleachother.

Stillanotherexperimentgaveusanideaofthelimitswithinwhichwecouldwork.MissBarbaraArndt,asummerstudent,raisedalitterofsixbeaglesinalargefield,makingdirectcontactwiththemonlyonceaweek,whenthevwere

largefield,makingdirectcontactwiththemonlyonceaweek,whenthevwereweighed,andeverytwoweeks,whenshegavethemahandlingtest.Shelefttheparentsadishoffoodonceeachday,immediatelygoingawaytomakeobservationsfromthegate,whereshestoodabout20or30feetawayfromthepuppieswithonlyherheadandshouldersshowing.Twoofthepuppiesweretakenawayfromtheparentsat3weeks,raisedbyhandfor2weeks,andreturned.Undertheseconditions,noneofthepuppiesbecameexcessivelytimid,althoughallsixeventuallyshowedavoidancescoresabovethemeanofthoseraisedinthelaboratorywithdailycontactwithpeople.Thehand-rearedpuppiesweretheleasttimidwhenreturnedtothepen,buteventuallygrewmoretimidandmuchliketheothers.Fiveofthesixpuppiesweremuchmoreresponsivetotheobserverthantoanvoneelse,andnoneofthemactedlikethewilddogsofearliertests.Itbegantolookasifaprimarysocialrelationshipwithahumanbeingcouldbeformedwithaverysmallamountofcontactduringthecriticalperiodand,infact,thatitmightbeformedmerelybyhavingthepersoninsightatfrequentintervals.However,thepuppiescouldstillhaveassociatedtheobserverwithbeingfed,andbecomesocializedinthatway.

The"wilddog"experiment.—Withtheseresultsinmind,Freed-man,King,andElliot(1961)designedanexperimentbasedonlargenumbersofpuppies.Thevusedthelargeoutdoorfields,introducingfoodandwaterthroughaholeinthefencesothattherewasalmostnocontactwiththeexperimenters.Thevbroughtineachexperimentalpuppyforonlyoneweekandgaveitstandardizedcontactwiththeexperimenterseachdaw

Fromtheevidencecitedabove,theexperimenterssupposedthatthecriticalperiodextendedroughlyfrom3to7weeksofage,andtheyattemptedtosocializepuppiesat2,3,5,7,and9weeks,leaving

THECRITICALPERIOD

125

certainpuppiescontinuouslyaloneuntil14weeks.Atthistimeallthepuppieswerebroughtintothelaboratoryandretested.

Theresultscanfirstbeanalyzedintermsofinitialeffects.Thepuppiesweregiventhehandlingtestimmediatelyafterbeingbroughtinandagainafteraweekofhumancontact.Figure5.2

23456AGEINWEEKS

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Fig.5.2.—Effectofsocializationatdifferentagesuponavoidanceofanactivehandler.Noteconsistentriseofavoidancescoresafter5weeksofage.Alargenumberoftheresponsesat2and3weeksofageareofthe"noresponse"category;hencescoresattheseagesarenotcompletelycomparabletothoseatlaterages.Lengthoflinesdenotesthechangeresultingfromcontact;topoflineindicatesinitialscore.

showsthatthepuppiesbroughtinat5weeksofageshowedtheleastinitialavoidanceofhumanhandlers,whilethosebroughtinearlierorlatershowedlargernumbersoffearresponses.Nevertheless,afteraweekofcontactwiththeexperimenters,thepuppiestakenat3weeksofageshowedtheleastfear,andthosetakenat5weekswererelativelytimid.Thus,themaximumreductionoffearwasproducedat3weeks,andtheminimumat5.

Inanothertest(the"PassiveHandlerTest"),theexperimentersatquietlyintheroomwiththepuppyeachdayfor10minutesandrecordedhowlongittookthepuppytoapproachandremainincontact.At2weeks,thepuppiesweresoimmaturethatitwas4daysbeforetheybegantospendthefulltimewiththeexperimenters.At

3and5weeksthisoccurredonthefirstday,butitwastwodaysbeforethe7-week-oldpuppiespassedthetest,andthreedaysbeforethisoccurredwiththe9-week-oldpuppies.

Thuswehavemeasuresofseveraldifferentkindsofbehavior.Thefirstisthepositiveresponseofmakingcontactwithapassiveandhencenon-frighteningnewindividualintheenvironment.Thisbe-

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Fig.5.3.—Timingmechanismslimitingtheprocessofsocializationinpuppies.Initially,thepuppiesareunabletorespondtoanactivepersonbutshowlittlefear.Later,thedevelopingfearresponselimitsthecapacitytobeattracted.

haviorismostobviousfrom3to5weeksofageanddeclinesthereafter.Second,thereisthenegative,orfearresponse,tonewandactiveindividuals,whichcontinuouslyrisesafter5weeksofageandprobablycausesthedeclineoftheearlierapproachbehavior.Third,thereistheresponseofrecoveryfrominitialfears,whichisalmostinstantaneousat3to5weeksofageandbecomesprogressivelyslowerthereafter.Allthesebehavioralprocessesaffecttheformationo!theyoungpuppy'sfirstsocialrelationshipsduringthecriticalperiod.TheirnetresultisthatthepuppymakesrapidcontactwithacompletelystrangeindividualonlywithintherelativelyshortperiodFrom3to5weeksofage.

THECRITICALPERIOD

127

Wemaynowconsiderthelatereffectsoftheseexperiences.Thepuppieswereallremovedfromthelargefieldsat14weeksofage,broughtintothelaboratoryrearingrooms,andsubjectedtoaseriesoftests,includingnewonesaswellasthosepreviouslygiven.Onetestwhoseresultsshowedthelargestdifferenceswasthatofleash-control.Apuppywhichhasneverbeenonaleashbecomesalarmedandfearful,bothinreactiontorestraintandtobeingledintostrangeplaces.Thetestconsistedofleadingthepuppythroughthelaboratorybuildingandupthestairs(themostfrighteningpartofthetrip)andisdescribedindetailinchapter9.TheresultsareshowninFigure5.4.Thoseanimalstakenat5,7,and9weeksmadethebest

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Fig.5.4.—Performanceintheleash-controltest.Animalssocializedat5,7,and9weeksofagebalkedfewertimeswhenledintostrangesituations.

scoresontheover-alltest.Animalsbroughtinforthefirsttimeat14weeksandthosetakenat2and3weeksdidmuchworse.One14-weekanimalwasgivenintensivehumancontactandtrainingforoveramonthandshowedonlyslightimprovement.

Partofthetestincludedofferingafoodrewardattheendoftheroute.Severelyfrightenedanimalsrefusedtoeat,andthebestresponsewasmadebythoseanimalstakenat5and7weeksofage(Fig.5.5).Whenwetakeallagestogetherandrankthemaccordingtoperformanceoneachtest(Table5.3),weseeadefinitetrend.The

BEHAVIORPATTERNS

45

0246810

AGEWHENSOCIALIZED

Fig.5.5.—Eatingduringtheleash-controltest.Animalssocializedat5and7weeksofageatemoreoftenthantherest.

controls(14-weekgroup)gavethepoorestperformancein4outof6tests,whiletheanimalstakenat7weekswerebestin5outof6.Nextbestwerethosetakenat5weeks,confirmingourassumptionsregardingthelengthofthecriticalperiod.However,therelativelygoodperformanceofanimalstakenat9weeksshowsthatthereisno

TABLE5.3

RankOrderofPuppiesoxTestsGivenAfter14WeeksofAge(AfterFreeuman,King,andElliot,1961)

ranks.


sharpcut-offpointafter7weeks.Rather,thisseemstobethepeakfromwhichadeclineinthecapacityforsocializationbegins.Theendoftheperiodofsocializationmustbeplacedintheneighborhoodof12to14weeks.

Theresultsofthis"wilddog"experimentalsoleadtotheconclusionthatthe

Theresultsofthis"wilddog"experimentalsoleadtotheconclusionthattheprocessofsocializationisacomplexone,involvingseveralbehavioralmechanisms.Similarexperienceatdifferentageswillproducedifferentresults,butthefinaleffectsalsodifferwiththekindofbehaviortested.

BEHAVIORALMECHANISMSINEARLYSOCIALIZATION

Theeffectsoftransferringthecareofayounganimalofonespeciestothatofanotherduringorbeforethenormalperiodofsocializationaresostrikingthatoneislikelytobehighlyimpressedwiththeeffectofwhatseemstobeasimplebehavioralfactor.Thisis,however,acomplexphenomenoninvolvingmanydifferentbehavioralmechanisms.Weobtainedsomecluesastowhatthesemightbefromthefollowingexperiments.

Manyyearsagowetookafemalelambawayfromthemotheratbirthandraiseditonabottlefor10days(Scott,1945).Wethenreturnedhertothefieldinwhichtheparentflocklived.Sheapproachedtheothersheepcuriously,butthefemalesbuttedher,andshemadenofurtherapproaches.Threeyearslaterthisanimalwasstillfollowinganindependentcoursearoundthefield,notjoiningtheflock,eventhoughshehadbeenmatedandhadbornelambsofherown.Wethentriedthesameexperimentwithayoungmalewhichhadbeenrejectedbyitsmotherandraisedonthebottle.Duringthefirsttwoorthreedayshehadsomecontactwithothersheep,sothattheexperimentswerenotexactlycomparable.Themaleactedinthesamewayasthefemalewhenhewasyoung,butashegrewolderandbecamesexuallymaturehebecameinterestedinthefemalesandbegantoassociatewiththeflockmoreandmore.Thisshowedthatoneofthepositivemechanismsproducingsocialrelationshipsintheflockisthesexualbehaviorofmales,althoughthisfactorisunimportantinfemales.

Later,Collias(1956)performedaseriesofexperimentsattheCornellUniversityBehaviorFarmwhichclearlybroughtoutsomeofthebehavioralmechanismsofprimarysocializationinthesheep.Ifalambistakenfromitsmotheratbirthandreturnedatanytimewithinfourhours,shewillacceptitandallowittonurse.Afterthis

timesherejectsit.alons;withanvotherstrangeIambs.Thusthecriticalperiodforsocializationinsheepisshortandsharplylimited,butlimitedbythebehaviorofthemothersratherthanthatofthelambs.

Meanwhile,wedidanexperimentwithavoungfemalepuppy,similartotheonewehadlonewiththenewbornlambs,andexpectedtogetasomewhatsimilar

wehadlonewiththenewbornlambs,andexpectedtogetasomewhatsimilarresult.WetookahybridpuphichsoonbecameknownasChristy)andraisedherfrombirthcompletelyawayfromotherdoss,withtheenthusiastichelpoftheentiresummerstudentcolonyattheJacksonLaboratory.Asmiz-'havebeenexpected,shebecameavervfriendlypuppy,normalinhealthandappeara:.dcA:sofas;eweintroducedhertoother

dogsforthefirsttime.Shewassomewhatfearfulatthestart,butnotforlong.Althoughadultanimalsdidsomegrowlingather.theymadenorealattacks.WhenshewasplacedwithherownUttermatestheyreactedwithplavfulas;ness,towhichsherapidlyre-

sponded.Within4days,shecouldnotbetoldapartfromtheotherseptthatsheomewhatmoreresponsivetohumanbeings.

Thisindicatedthatoneofthepositiveresponseswhichleadstosocializationistheplavfulaggressivenessofvounsjpuppies.Italsoindicatedthatrejectionofstrangeyounganimalsbyadultsisnotasimportantinlimitingsocializationinthedoâsitisinthesheep.

cannowbegintoclassifysomeofthebehavioralmechanisms:ehenterintotheprocessofsocialization.Therearepositivemechanismswhichtendtoproduceclosecontactduringtheinitiationofalastingrelationship.Ontheotherhand,therearenega:mechanismswhichpreventsucharelationshipfrombeingsetupwithallanimals.Undernaturalconditionsthesenegativemechanismspreventtheformationofrelationshipswithanyotherspecandusuallylimitcontactstoafewanimalsofthesamespecies.Asshowninthesheep,positiveandnegativemechanismsofbehaviorarefoundbothintheyoungindividualandinothermembersofthesocialgroup.

Individualmechc.—Thepositiveresponseofanyvoungpuppytoanewanimalorobjectinitspenistoapproachitandin-gtteitwithitsnose,perhapsalsobitingandchewingitifthisispossible.Whenthenewanimalisanotherpuppythismaydevelopintoplavfulfighting,withthepuppiespawingandchewingoneachother.Astheygrowolderwealsoobserveplavfulsexualbehaviorwithc.gandmounting.Fairlvearlvinthecriticalperiodwe

seethetendencytowardafielomimeticbehavior,withpuppiesfollowingeachotherandreactingasagroup.Socialinvestigation,



allelomimeticbehavior,playfulfighting,andplayfulsexualbehaviorallbringthepuppiesintocontactandkeepthemtogether.

Ingestivebehaviorisprobablynotasimportantastheaboveindrawingthepuppiestogether,sincethepuppiestendtogrowloverthepossessionoffoodevenataveryearlyage,butfooddoesenterintotherelationshipwiththemother.Theappearanceofthemotherisasignalforthepuppiestocrowdaroundher,eitherattemptingtonurseorwaitingforhertovomitfood.Thismaybeavestigeofthewolf"greetingceremony,"whichinvolvestailwagging,licking,andmuzzlebitinginastereotypedfashion(Ginsburg,1963).

Themostimportantnegativemechanismisagonisticbehavior.Theimmediateresponseofapuppytoanythingnewinitsenvironmentistorunawayorshowsomesortofstartleorfreezingbehavior.Inafreesituation,likethatinthewilddogexperiment,thecapacityforescapedevelopsrapidly,sothatbythetimeapuppyis4monthsofageitispracticallyuncatchable.Thisfearresponsecouldprobablybepartiallyovercome,butitwouldtakeweeksofpatienteffort,justasitdoeswhenoneattemptstomakecontactwithawildanimal.Alongwithescape,thepuppydevelopsthecapacityformoreseriousfighting.Ourexperimentsindicatedthatmostofthepuppieshaddevelopeddominancerelationshipsby11weeksofage,andthatthesewerewellstabilizedby15weeks.Thusthebehaviorofanolderpuptowardastrangerislikelytobeaseriousattackratherthanplayfulfighting.Thiseffectivelypreventstheformationofasocialbond.Figures5.7to5.9showthatthedevelopmentofthesebehaviorsisgradualratherthaninstantaneous.

Socialmechanisms.—Aswellasreactingtoitssocialenvironment,thepuppyisacteduponbyotheranimals.Thefirstimpactofthesecomesfromthecare-givingbehaviorofthemother.Thisismostintenseduringtheneonatalperiodwhenthepuppieslackthecapacitytoformacomplexrelationship.Duringtheperiodofearlysocializationthemotherstillapproachesthepuppies,allowsthemtonurse,cleansthemiftheyaredirty,andvomitsfoodforthem.However,herbehaviorduringthisperiodismuchlessintenseandlessensasthepuppiesgrowolder.Themotheractsasifherattachmenttothepuppieswasstrongestduringtheneonatalperiod,growingweakerthereafter.

Anotherpositivemechanismactingonthepuppyistheplayfulbehaviorofsiblings.Duringtheperiodofsocializationapuppyisconstantlyapproachedbyhislittermatesandstimulatedtothiskindofbehavioraswellasinitiatingit

hislittermatesandstimulatedtothiskindofbehavioraswellasinitiatingithimself.

Undernormalcircumstancesthereisverylittleopportunityfor

negativemechanismstoactduringearlylife.Theneonatalpuppylackstheabilitytomakecontactwithstrangemothers,andevenifitisplacedwithastrangefemale,thelatterdoesnotshowthestrongpatternofrejectionseeninsheep.Manymotherswillacceptstrangepuppieswithoutdifficulty,althoughothershavebeenknowntokillstrangepupsofferedforadoption.Whenolder,thepuppiescanapproachstrangersontheirownpower.Adultdogsusuallygrowlatstrangepuppies,althoughtheyseldomifeveractuallyhurtthem.Suchcontactsusuallyhappenlongaftertheprimarysocialrelationshipshavebeenestablishedandresultintheestablishmentofdominanceratherthanseparation.

Asecondnegativefactoristhedevelopingaggressivebehaviorofpuppies.ThiswasbroughtoutclearlyinanexperimentbyFisher(1955).Hetooklittersoffourfromfoxterriermothersandraisedtheminboxeswhichisolatedthemfromthesightofotherdogsandpeople.Twofromeachlitterwereraisedtogethersothateachhadtheconstantcompanyofanotherdog.Anotherwastakenoutatregularperiodsforcontactwithpeople.Thefourthanimalwasgivennoanimalorhumancontactsuntilitwasremovedfromthepenat16weeksofage.AtthistimeFisherattemptedtoputthelitterbacktogether.Thepuppywhichhadbeencompletelyisolatedwasstrikinglydifferentfromtheothers,standingaroundinwhatappearedtobestupefiedastonishment.Thereactionoftheotherpupswastoattackit.Whiletheisolatedpupfoughtback,itwasineffectual,anditalwayscameoutonthebottomofadominanceorder.Thismeantthatthefirstcontactoftheisolatedpuppywithotherdogswasassociatedwithbeingattackedandthreatened,effectivelypreventingthedevelopmentofapositiverelationship.Theexperienceofsuchpuppieswaslikethatofabottlelambattemptingtorejointheflock.

Fisherfinallyputfouroftheseisolatedanimalstogetherinthesamepenandfoundthattheylivedpeaceablytogether.However,theyneverformedaclosepositiverelationshipandplayedindependentlyofeachother.Iftheyhadbeenplacedinalargefield,itislikelythattheywouldhavebehavedagooddealliketheorphanlambwhichstayedawayfromtheflock.

Stillfurtherobservationsontheseisolatedpuppiesthrowmorelightontheirbehavior.Inconnectionwithanotherprojectweraisedalargenumberofbeagles

behavior.Inconnectionwithanotherprojectweraisedalargenumberofbeaglesinisolationuntil16weeksofage(Fuller,1CX)1).Whenfirstplacedwithotherpuppies,theygavenoreactionandtheotherseitherignoredthemorgrowledatthem.However,whenwetookthesesamepuppiesandbegantohandleandplaywith


them,weelicitedthesamesortofplayfulfightingbehaviorwhichistypicalofpupsatayoungerage.Withinafewdaystheywerereactingnormallytopeople.

By16weekstheseisolatedpuppieshadlostthecapacitytoexhibitplayfulbehaviorspontaneously,althoughitcouldbeelicitedbyexternalstimulation.Bythisage,normalpuppieshaveconcentratedthisbehaviorinspecialrelationshipsandnolongerofferittostrangers.Thusanotherfactorenteringintothelimitationofthecapacityforsocializationisthelossofthecapacityforinitiatingplayfulbehaviortowardstrangers.

GENETICDIFFERENCESAFFECTINGTHESOCIALIZATIONPROCESS

Oneofourbestobjectivemeasuresofsocializationinpuppiesisthehandlingtest.Inthistestwedoallthethingswhichpeopleordinarilydotopuppies.Firstwetakethemoutsidetheirhomeroomandallowthemafewminutestobecomeaccustomedtotheholdingcage.Thenthehandlertakesthembackintothehomeroom,oneatatime.Firstheplacesthepuppyafootortwoaway,standsperfectlystill,andnotesanyreactionswhichoccurinthenext15seconds.Thenhemovesslowlyaway,turns,andsuddenlywalkstowardthepuppyfromadistanceof5or6feet.Thisisthemostfrighteningpartofthetest.Thehandlerthensquatsdownandholdsoutahandtowardthepuppy.Ifitcomesupandtouchesthehand,theexperimenterliftshishandintotheairsothatthepuppycanjumpupandtouchitifitlikes.Thenthehandlerrepeatsthesamebehaviorbutcallsthepuppyatthesametime.Hethenstrokesthepuppygentlyfiveorsixtimesandfollowsthisbypatting.Atthispoint,thehandlerpicksthepuppyupandobservesitsreactions.Thenheputsitdownagainandrepeatsthestrokingandpattingtechnique.Thefinalpartofthetestisanother30-secondperiodinwhichthehandlerstandsperfectlystillandallowsthepuppyfreeactivity.

Inrecordingdatawemarkonachecklistwhateverthepuppydoesasanimmediateresponsetoeachtypeofstimulation.Noattemptismadetoestimatetheintensityordurationoftheresponse;onlyitsoccurrenceisrecorded.Thustheresultsgiveusthenumberoftimesinwhichaparticularkindofbehaviorhas

theresultsgiveusthenumberoftimesinwhichaparticularkindofbehaviorhasbeenstimulatedor,inotherwords,thenumberoftimesthethresholdofresponsehasbeenreached.

Thedifferentpartsofthetestcanbethoughtofasstimuliofdifferentintensity.Walkingtowardtheanimalismostlikelytostimulate

BEHAVIORPATTERNS

fearfulreactions.Squattingandcallingthepuppystimulatesanapproach,whereaspattingandstrokingarelikelytobringoutplayfulrighting,atleastinolderpuppies.

Escapeandavoidancebehavior.—Averytimidpuppywillrunawaytothecorneroftheroom,crouch,andgiveahigh-pitchedvelpwhichisunmistakablyfearfulintone.Whenwemeasurethisbe-

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havior,wefindthatthebasenjisasabreedaremuchmorefearfulthantheothers

havior,wefindthatthebasenjisasabreedaremuchmorefearfulthantheothersat5weeksofagebutshowagreatchangeby7weeksinresponsetothefrequenthandlingreceivedindailytestingbetweenthosetimes.Thereaftertheamountofescapebehaviorstaysquitelevel(Figs.5.6and5.7).Theotherbreedsshowmuchlessfearat5weeksandrelativelylittlechangeatsubsequenttestingperiods.Underthestandardconditionsofrearingupto5weeksofage,thepuppiesgetlittlecontactwithpeopleexceptwhenfoodisbroughtin

THECRITICALPERIOD

135

onceeachday.Thisamountofcontactisenoughtopreventthedevelopmentoffearfulbehaviorinmostofthebreeds,butitisnotenoughforthebasenjis.

Puppiesraisedunderotherconditionsmaynotshowthesebreeddifferences.Forexample,apuppyraisedinahomefrombirthwillshowalmostnofearfulbehaviortowardpeopleat5weeks,nomatterwhatthebreed;andour3home-rearedanimalsshowedaminimumamountofescapebehaviorinthehandlingtest,theirscoresbeinglocatedverynearthelowerendofthescaleintheirrespective

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Fig.5.7.—Avoidanceandfearfulbehaviorinresponsetohandling.Basenjishavemuchhigherscoresattheoutset,andthescoresofallbreedsfallduringthenext2weeks.Atoneyearofagedogsrespondtothistestastheywouldtocatching,andthescoresofallbreedsaremarkedlyhigherexceptforcock-

ers.

breeds.Undertheseconditions,breeddifferencestendtodisappear.Breeddifferencesalsodisappearwhenpuppiesaregiventhemaximumopportunityto

differencesalsodisappearwhenpuppiesaregiventhemaximumopportunitytodevelopfearresponsesinthelargefields.Fromourexperiencesinthelaboratorywehadexpectedthatcockerspanielsandbeagleswouldbecomenaturallyfriendlydespitetheirlackofcontactwithhumanbeings.Suchwasnotthecase.Evencockersbecameaswildandfearfulasotherbreeds,theonlydifferencebeingthatwhencaughttheydidnotbitequiteashard,probablybecauseofselectioninthecockersfora"softmouth,"usefulinretrieving.

BEHAVIORPATTERNS

Ourresultsindicatedthatthebasenjishadagreatercapacityfordevelopingescapebehavior,probablybecause,asAfricanvillagedogs,suchbehaviorhadsurvivalvalue,whereasinotherbreedsthistraitisconsideredundesirablebymostdogowners.Wecanalsoconcludethatsuchfearresponsescanbegreatlymodifiedineitherdirectionbytrainingandexperience,andthatgeneticdifferencesarelessimportantateitherextreme.

Aggressivebehavior.—Breeddifferencesinaggressivebehaviorcanbemeasuredinthehandlingtest,butweneveractuallyobservedanyseriousattacksoreventhreats.Allreactionswerestrictlyplayful,andthemostextremeonesconsistedofpawingandgentlybitingtheexperimenter'shandsorclothing.AsseeninFigure5.8,

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Fig.5.8.—Agonisticbehavior(playfulfighting)inresponsetohandling.Thisscoreconsistschieflyofplayfulbitingandpawing.Notethatcockersareconsistentlylowerthanotherbreedsandchangetheleastat1yearofage.

thisbehaviorreachesitsheightabout13to15weeksofage.Weshouldremember,however,thatmostofitisnotspontaneousbutstimulatedbytheactiveapproachofthehumanhandler.Thereappeartobedefinitebreeddifferences,withwire-hairedterriersatthetopandcockerspanielsatthebottomofthescale.Theresultsgenerallyagreewiththereputationofthebreedsforfightingability,exceptthatthebeaglesshowasurprisinglyhighrank,andthisisabreedwhichshowsalmostnotendencytowardrealfighting.Itap-


pearsthatplayfulaggressivenessandseriousaggressivenessarenotnecessarilycorrelated.

Wealsohaveconfirmingevidencefromdominancetests.Thebestindicationofaggressivenessistheexistenceof"completedominance,"inwhichonepuppyalwaystakescommandoverabonepresentedtoapair.Thewire-hairedterriersdevelopalargenumberoftheserelationshipsbefore15weeks,otherbreedsbeingslower(Fig.6.1).Byoneyearofagesheltiesandbasenjishavenearlycaughtup,butbeaglesandcockerspanielsneverdevelopalargenumberoftheserelationships.Wecanconcludethattheterriersarethemostaggressive,thebasenjisandsheltiesnext,andtheothertwobreedsmuchtheleast.Wecanalsosupposethatthesocializationofastrangepuppvtoagroupoffoxterrierswouldbepreventedbyaggressivenessbefore11weeksofage(whichcorrespondstoourobservationsoftheseverefightingthatbreaksoutinthisbreedasearlyas7weeks),andthatthesocializationofastrangertoabasenjigroupwouldbeinhibitedsomewhatlater,perhapsby15weeks.Inthemorepeacefulbreeds,thisfactormightbequiteunimportant.

Socialinvestigationandattraction.—Oneoftheprimaryreactionsinvolvedinsocializationisthepuppy'stendencytocometowardahandlerandinvestigatehim,usuallywaggingitstailatthesametime.Thiskindofbehavioroftenappearsinthehandlingtestandreachesitsheightabout7weeksofage,stayingatafairlyconstantlevelthereafter(Fig.5.9).Suchactivitymaybedividedintoinitialattractionandsubsequentinvestigatorybehavior.Consideringat-trationalone,thebasenjisappeartobelessattractedtopeopleatallages(Fig.5.10).Sheltiesarelowatcertainages,andcockersareconsistentlyhigh.

Asomewhatdifferentpictureispresentedbythesocialinvestigativebehaviorshownafterthepuppiesreachtheexperimenterandbeginnosinghishandsandclothes(Fig.5.9).Thebeaglesexhibitedmoreinvestigativebehaviorthanother

clothes(Fig.5.9).Thebeaglesexhibitedmoreinvestigativebehaviorthanotherbreeds,althoughcockerspanielswereslightlyhigherat5weeks,justastheywereintheattractionscore.

Thedevelopmentoftailwagging.—Thepatternofrapid,horizontaltailwaggingisoneofthemostcommonlynoticedbehaviorsindomesticdogs.Itbeginsataveryearlyageandcontinuesaslongasthedoglives,appearingmostofteninsituationsinwhichthedogisfriendlyandsubmissive.Ithasnofunctionotherthanasocialone,andinalltheserespectsismuchlikethehumansmile.

Itsdevelopmentcanbechartedfromtherecordsofourdailyob-

BEHAVIORPATTERNS

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FlG.5.10.—Attractionandfollowinginresponsetohandling.Basenjisareconsistentlylowinthisscorecomparedtootherbreeds,butsheltiesshowthegreatestdecreaseat1year.

THECRITICALPERIOD

139

servations.Aresearchassistantwatchedeachlitterfor10minutesadayandrecordedeverythingthatthepuppiesdid,latercheckingeachitemonastandardlist.Inthiswaywehavearecordofthefirstdayonwhicheachpuppvwasseentowagitstail.

Tailwaggingfirstappearedat17daysofage(Table5.4a).By30daysone-halfofalldiepurebredpuppieshadbeenseenwaggingtheirtails.Thisbehaviorthusbeginsearlyintheperiodofsocializationandrapidlyincreasesinfrequency.

TABLE5.4aDevelopmentofTailWagging

Whenwecomparethedifferentbreedsweseecertainobviousdifferences.By18daysofageone-fourthofthecockerspanielswereseenwaggingtheirtails,whereasitwasnotuntil30daysofagethatbasenjiswereobserveddoingthis.Atthislatterage83percentofthecockershadbeenseentailwagging.Therestofthebreedswereverysimilartoeachother,withabout50percenttailwaggingby30daysofage(Table5Ab).

TABLE5.46DevelopmentofTailWagging:Occurrenceat30DaysorEarlier

Thedifferencesbetweencockersandbasenjisarehighlysignificant,andbothbreedsalsodepartwidelyfromtheaverageofallbreeds.Wethereforehaveanimportantbreeddifferenceinthede-

'-:

velopmentofaformofsocialbehaviorcloselyconnectedwiththeprocessofsocialization.However,thedifferencebetweenbasenjisandco:orobablyoneofthresholdsofstimulationratherthan

rateofdevelopment,sincethereisalmostnodifferenceintailwag-_I.enbothbreedsarestronglystimulated,astheyarewhentheyarebeing_entheirweeklyweighings.Cockersapparendywagtheirtailsinresponsetoaslightstimulus,whilebasenjisrequirestrrr.ge:stu.îzizz

Theseresultsshowthatgeneticfactorshaveimportanteffectsontheprocessofsocialization.Heredityaffectsboththeindividualreactionswhichlimitsocializationfromwithin,suchasfearre-srrzjri::~er^Srn-'ii.ir.£-:;e~:::■:::::;lir/_i::r.-sziilizi::::fromwithout,suchastheaggressivenessofthefoxterriers.Inaddition,geneticfactorscanaffectthepositivebehaviorofapproach:.~i5;::il:r.Ti:;::.:::::

Oi-.e-::55:":"r::::'::i:iif:':.:■.-{z.esei:E^:z:.:~?ire:ie:e.;i:::asingletraitoffearfulnesswhichcould,ofcourse,affectalltheothers.This,hwillnotexplaintheresults.Thebasenjisare

themostfearfulatfirstandshowtheleastattraction.HowetheyarenotthelowestinsocialinvestigationandareactuallysecondhighestinplayfulaggressrveETireobviouslydealingherewithanumberofseparatetraitswithdifferentgeneticbases.

Thisseparationoftraitsalsogivesusaduetowardunderstandingtheorganizationofbehavior.Ourusualassumptionisthatfearfulnessandaggressivenessaretheoppositeendsofasinglebeh.ioralscale.Thisisnotthecasewithdogs.Abreedmayhavethecapacitytobecomebothhighlyfearfulandhighlyaggrein

thebasenji;orhighlyaggrebatnotfearful,asinthefoxterr

orshowingneitherextreme,asinourotherthreebreedlso

seethatevenaggressivenessisnotaunitarytrait,forabreedlikethebeaglescanshowbothahighdegreeofplayfulaggressivenessandaverylowamountofseriousaggressiven-

Ing:hebehaviorofdomesticdogsshowstheresultofselec-

tionagainstthedevelopmentoftheescapeandavoidancebehaviornormallyfoundinwolves.Thismeansthatthedevelopmentofoneofthefactorslimitingtheperiodofsocializationhasbeendelayed,sothatsuccessfulsocializationcanbeachievedatamuchlaterij>.achievedgoodsocializationwithawolfpuppybdbeforetheeyesopened.Crisler(1958)apparendywassomewhatlesssuccessfulwithpuppiestakenataslightlylaterage,althoughthesituationwasnotstrictlycomparable,inthatsheraisedapairratherthanasingleindividual

THECRITICALPERIOD

Ginsburg(1963)hasrecentlvdemonstratedthatwolvescapturedasadultscanbesuccessfullysocialized.Theprocesstakesmanydaysandthewolvesmustbekeptinapensotheycannotescape.Theexperimenterentersthecageandmaintainsapassiveroleuntilthewolfmakesitsfirstpositiveadvance.Atthispointhemustneitherthreatennorwithdrawfromthewolf,butmustrespondappropriatelyandpositively.Ifthereissuccessfulmutualadjustment,thewolfwillthereafteracceptnotonlytheexperimenterbutotherhumanbeingsaswell.Suchresultsindicatethatthecapacityforformingnewsocialrelationshipsisnotlostinanadultbutisordinarilypreventedfromfunctioningbyescapeandfearreactions.

Therehasbeenselectionfordecreasedaggressivenesswithinmanydogbreedsinordertomakethemeasiertohandle.Inthecaseoftheterriers,however,selectionforaggressivenesshasproceededintheoppositedirection.Thisdoesnotseemtohavelimitedthecapacityforsocialization,sinceoneofthepositivemechanismsofsocializationisplayfulfighting,butrathertohavelimitedthecapacityforgroupliving.Thereisnoindicationthatthetendencytowardsocialinvestigationhasbeenprolongedinanybreed,exceptbytheeliminationoffearfulbehaviorwhichinterfereswithit.Aslongastheyarenotafraid,membersofallbreedsactliketypicalfriendlypuppiesuntilatleast15weeksofage.Somebreedsshowmoreplayfulbehaviorthanothers,butthereisnotrueprolongationofanimmaturesocialstate.

THECRITICALPERIODINOTHERSPECIES

THECRITICALPERIODINOTHERSPECIES

Thefundamentaltechniquefortestingtheexistenceoftheprocessofsocializationistofosteravounganimalonanotherspecies.Withhigheranimalsitisofteneasiesttodothisbyhandrearing,butthelivingrequirementsofotherssuchasthesocialinsectsmaybesodifficulttoduplicatethattheycanonlybefosteredonsimilaranimals.Ifthefosteredanimaltransfersitssocialrelationshipstothenewspecies,wecanconcludethatsocializationhastakenplace.Thenextstepistoattemptthisatvaryingagesinordertotestfortheexistenceofacriticalperiodfortheprocess.Suchexperimentshavesofarbeendonewithonlyalimitednumberofspecies,butresultsaregenerallyconsistent.

Insects.—Antcoloniesusuallyattackstrangespeciesandoftengivethesamereactiontostrangemembersofthesamespecies.Ifyoungantsareexperimentallyplacedinastrangecolonytheybecomeapermanentpartofit,beingcaredforbytheresidentworkers.

Thisregularlytakesplaceintheslave-makingants,whichraidcoloniesofotherspeciesandbringbackyoung.Thesecapturedindividualsthengrowupandtakecareoftheyoungoftheirmasters.Noattempthasbeenmadetofindacriticalperiod,butitmustendsoonaftertheadultsemergefromtheirpupalcases,ifnotbefore.

Honeybeesalsorecognizemembersoftheirowncolony.Aswithants,recognitionisbasedonscentandhasbeenshowntobeanacquiredratherthananinheritedreaction.Furthermore,beesoftwocoloniescanbebroughttogetherwithoutfightingprovidedtheyhavebeenfedonidenticaldietsforasufficientlengthoftime(Ribbands,1953).Thereisnodirectevidenceastowhenthescentofthewholehomecolonyislearned,butitmustbeearlyinlifebecausetheworkerstendtotakeupguarddutiesbeforetheybecomeforagers.Beforebecomingguards,theyoungbeesworkaroundthehive,cleaningthecells,sothatthereisampleopportunitytolearnthescentofthehive.Thus,socializationdoestakeplaceamongsocialinsects,andprobablyduringashortperiodearlyinlife.

Birds.—Thegreatimportanceoftheprocessofprimarysocializationwasfirstrecognizedinbirds(Lorenz,1935).ThenaturalistHeinrothhadattempted,withcharacteristicGermanthoroughness,tohandrearallofthecommonEuropeanspeciesofbirdsinordertolearnmoreabouttheirdevelopmentandbehavior.Someoftheresultswerespectacularexamplesoftransferenceofsocialrelationshipsfromonespeciestoanother.Inonecase,althoughtheadultbird

relationshipsfromonespeciestoanother.Inonecase,althoughtheadultbirdmatedwithamemberofitsownkind,itwasattractedawaybyitsfosterparentwheneverheappeared.KonradLorenzextendedtheseobservationsandmademorespecificstudiesoftwospecies,thegraylaggooseandthejackdaw.Geeseareprecocious,beingabletowalkandswimafewhoursafterhatching,whereasjackdaws,whicharerelatedtothecrowfamily,arehatchedinanimmaturestate.Lorenzfoundthatnewlyhatchedgeeseformedtheirsocialrelationshipswithinthefirstfewhours,whereasjackdawsdidthismoregraduallyatalaterstageofdevelopment.Oncetheserelationshipswereformed,itwasdifficultifnotimpossibletorestorethenaturalrelationships.LorenzcalledtheprocessofformingthisprimarysocialrelationshipPriigung,whichhasbeentranslatedas"imprinting."Thewordalsomeansimpress,andthismighthavebeenabettertranslation.Atanyrate,theyoungbirdsseemtobedeeply"impressed"or"imprinted"byalimitedexperienceearlyinlife.

TheFundamentalimportanceoftheseresultsinrelationtotheoriesoipsychiatryregardingearlyexperiencewassoonrecognized.Fa-


bricius(1951),Collias(1952),Hess(1959),andothersfollowedupLorenz'workwithdetailedanalyticalstudies.Inprecociousbirdslikeducksorchickens,thereisindeedacriticalperiod.Itiseasiesttodemonstrateimprintinginthechickatabout13to14hoursafterhatching,anddifficultifnotimpossiblebv30hours.Theprimarybehavioralmechanismswhichlimittheperiodare,atthebeginning,thedevelopmentoftheabilitytomovetowardastrangeobjectorpersonand,attheend,thedevelopmentofafearresponsewhichkeepsthebirdsfromapproachingstrangeobjects.Stillothermechanismsareinvolved;asHess(1957)hasshown,aducklingbecomesmorefirmlvimprintedifithastomakeanefforttofollowamodel.

Comparablestudieshavenotbeenmadewiththemoreslowlydevelopingbirds,exceptfortheveryexcellentdescriptivestudiesofMargaretNiceonsongsparrows(1943).Itisevidentthatsuchbirdsaremuchmoreliketheslowlvdevelopingmammalsthanarechicksandducks,andthatcomparableperiodsofdevelopmentexist(Scott,1962b).

Mammals.—Manyspeciesofmammalsotherthandogsandwolveshavebeenexperimentallyhandreared,andmostoftheseshowaspectacularattachmenttotheirhumanfosterparents.Chimpanzees,forexample,readilybecomemembersofhumanfamilieswhenraisedinhomes(Kellogg&Kellogg,1933;Hayes,

ofhumanfamilieswhenraisedinhomes(Kellogg&Kellogg,1933;Hayes,1951).Therehave,however,beenalmostnodetailedanalyticalstudiesofthecriticalperiodforsocializationexceptindogs,sheep,andguineapigs(Gray,1958).Theselasttwospeciesarehighlyprecociousandshowashortcriticalperiodveryearlyindevelopment.Thereareindicationsofacriticalperiodinrhesusmonkeysduringwhichcontactwithotheryounganimalsofthesamespeciesisnecessaryforthedevelopmentofbothsexualandmaternalbehavior(Harlowetah,1963).

Mammalsingeneraldifferagreatdealintheirspeedofdevelopment,somebeingborninarelativelymaturestate,andothersbeinghighlyimmature.Theremaybeagreatdealofvariationevenincloselyrelatedanimals.Forexample,rhesusmonkeysshowrapidandprecociousdevelopment,chimpanzeesandothergreatapesaremuchslower,andhumaninfantsareslowestofall.

Insummary,wecanstatethatallhighlysocialanimalswhichhavebeensofarstudiedshowacriticalperiodforsocializationearlyindevelopment.Themoreprecocioustheanimal,theshorterandearliertheperiodislikelytobe.Thebehavioralmechanismswhichlimittheperioddifferfromspeciestospeciesandcannotbepredictedinadvance.However,adevelopingfearreactionisacommonmechanism.

Itwouldbesurprisingifhumanbeingsdidnotshowatleastthevestigesofasimilarcriticalperiod.Thisconclusionwillreceivegreatersupportifthegeneralityofthephenomenonofcriticalperiodscanbeextendedbystudiesonawidervarietyofvertebrateandinvertebratespecies.

BASICNATUREOFTHEPRIMARYSOCIALIZATIONPROCESS

Wehavesofartalkedaboutthebehavioralmechanismswhichfacilitateorlimitsocializationbutlittleabouttheprocessitself.WhenLorenz(1935)firstwroteabouttheimportanceofimprinting,hestatedthattheprocesswasquitedifferentfromthatofconditioning,inthatitoccurredveryrapidlyandtheresultsseemedtobepermanent.Psychologistswerequicktopointoutthatconditioningcanalsooccurvervrapidlv,"one-triallearning"beingcommonplaceinhigheranimals.Furthermore,Pavlovhademphasizedthelongpersistenceofconditionedreflexes.Evenwhenareflexhadbeenextinguishedbynon-reinforcement,italwaysreturnedspontaneouslyafteranextendedperiodofrest.

Anattractiveandsimplealternatetheorvwasthattheemotionalbondbetweenmotherandoffspringwasproducedbyfeeding.Achildassociateditsmother

motherandoffspringwasproducedbyfeeding.Achildassociateditsmotherwiththepleasureofeating,andthisformedthebasisoftheattachmentwhichwaslatermoregeneralized.ThisideawasimplicitinFreud'sdescriptionoftheoralstageinhumandevelopmentandhassincebeenelaboratedasthetheoryofacquireddrives(MillerandDollard,1941).

Brodbeck(19.54)wasthefirsttotesttheseideasonthedog.Heraisedalitterofcockerspanielsandalitterofbeagles,takingthemawayfromthemothersat3weeksofage.Hefedhalfofthembyhand,andfedtheotherhalfbyasvstemofropesandpulleyssothatthepuppiesneversawwhofedthem.Hethengavebothgroupsthesameopportunitvtohavedirectcontactwithhimandlatertestedtheirreactionsashesatquietlyinthesameroom.Bothsetsofpuppieswerehighlyreactivetowardhim,andthoseofonegroupstayedwithhimjustascloselyasthosefromtheother.Wecancon-eludethatfeedingisnotanecessarypartofthedevelopmentofthesocialbond.Stanley|1962")andFeiderlaterdidasimilarexperimentwithtwolittersofbeagle-terrierhybridpuppies.Thehand-fedpuppieswouldvocalizemoreatthesightoftheexperimenter,butthiswastheonlyimportantdifferencebetweenthetwo.

ElliotandKing(1960)didtheoppositesortofexperimentin


thattheyhandfedagroupofpuppiesbutdidverylittleelsewiththem.Halfofthepuppiesweregivenalltheycouldeatandtheotherhalfwereunderfed.Whenthesepuppiesweregivenahandlingtest,theunderfedgroupshowedmorepositiveresponsestothehandlers,butbothgroupsshowedmoretimiditythanotherpuppieswhichhadbeenraisedintheregular"schoolfordogs"programinwhichtheyreceivedregularhandling.Fromthisexperimentwecanconcludethatfeedingbyitselfdoesnotproduceahighlysocializedanimal.

StanleyandElliot(1962)conductedaseriesofexperimentsinwhichtheypainstakinglyattemptedtodiscoverthefactorswhichmakeahumanbeingattractivetoyoungpuppies.Thebasicexperimentisamodificationofthepassive-handlertest.Beginningatabout6weeksofagethepuppiesareweaned,neverbeingfedbytheexperimenters.Theyarethentakenoneatatimetoadifferentroom,placedinasmallbox,andallowedtoruntowardanexperimenter.Thisisrepeateddailyforseveralweeks.Thepuppiesbecomehighlysocializedtohumanbeings,evenifthepersontowardwhomtheyrundoesnothingmorethansitpassively.Basenjipuppiesappeartobemoreattractedbyapersonwhoiscompletelypassivethanonewhoattemptstopet

attractedbyapersonwhoiscompletelypassivethanonewhoattemptstopetthem.Allpuppiesbecomecloselyattachedtohumanbeingswithnomorethanthedailycontactinvolvedintheexperiment.

Fisher(1955),inhisexperimentwithisolatedfoxterrierpuppies,treatedonegroupbypunishingthemwhenevertheymadeanypositiveapproach.Thesepuppieswererearedinspecialboxesfrom3weeksofageandwereneverfedbyhand.Aslongashecontinuedtopunishthem,thefoxterriersstayedaway;butoncehestoppedtheyalmostimmediatelyovercametheirfearandcametowardhim.Infact,theypaidmuchmoreattentiontohimthanacomparablegroupofpuppieswhichhehadtreatedwithuniformkindness.Theexperimentshowsnotonlythatfoodrewardsareunnecessaryingettingpuppiestobecomeattachedtopeople,butthattheywillformanattachmentinspiteofconsiderablepunishment.Wemustrememberthatthesewerefoxterrierpuppieswhichhavebeenselectedtotakeagooddealofpunishmentinfighting,andtheresultsmighthavebeendifferentwithamoresensitivebreed.

Meanwhile,Harlow(1958)hadbeenperforminganinterestingexperimentwithrhesusmonkeys.Thesearequiteprecociousanimalsasprimatesgo,andnormallyclingtotheirmothersimmediatelyafterbirthandcontinuetobecarriedbytheirmothersforseveralmonths.Harlowtookthebabymonkeysawayfromtheirmothers

146BEHAVIORPATTERNS

atbirthandofferedthemachoiceoftwoimitationmothers.Onewasdeliberatelyintendedtobeuncomfortable,beingmadeofwiremeshhardwarecloth,andtheotherwascoveredwithsoftterrycloth.Anursingbottlewasinsertedinthehardwareclothmother,andtheinfantgotallitsfoodinthisway.Harlowfoundthatthebabymonkeysspentalltheirtimewiththecomfortablemother,onlygoingbrieflytotheotherinordertonurse.Thebabymonkeysgaveeveryevidenceofbeingprofoundlyattachedtotheterry-clothmother,andHarlowconcludedthatthetheorythattheattachmentoftheinfanttothemotherwasanacquireddrivebasedonfoodrewardscouldbeabandoned.Hewasinclinedtoconsider"contact-comfort"astheessentialelementintheprocess.

IgelandCalvin(1960)wonderedwhatwouldhavehappenedifthemonkeyscouldhavechosenbetweentwocomfortablemothers,oneofwhichproducedmilkandonewhichdidnot.Nothavingmonkeysavailable,theydidacorrespondingexperimentwithyoungpuppiesandfoundthat,ifthepuppies

correspondingexperimentwithyoungpuppiesandfoundthat,ifthepuppieswereequallycomfortable,theyspentmoretimewiththemotherthatproducedmilk.Inshort,foodrewardswillstillaffectthebehaviorofayounganimal,evenifthesearenottheprimaryelementintheprocessofsocialization.

Meanwhile,otherpsychologistshadbeenexperimentingwiththeimprintingofbabychicksonvarioussortsofmodels.Atfirstitwasthoughtthatthemodelmustmovetobeeffective,butlaterJames(1959)showedthatchicksbecameimprintedonamodelwhichwasmerelyexposedtoflickeringlight.Finally,Gray(1960)didanexperimentinwhichbabychickswereexposedtoamotionlessmodelwhichtheycouldseebutnottouch,andtheirsubsequentbehaviorindicatedthattheyhadbecomeimprinted.Thebabychicksthereforebecameattachedtoanobjectwhichneitherrewardednoractivelystimulatedtheminanyway.

Takentogether,theevidencefromdiesedifferentspeciesofmammalsandbirdsleadstotheconclusionthattheprocessofforminganemotionalattachmenttomembersoftheparentspeciesislargelyindependentofoutsidecircumstances.Whetherrewarded,punished,ortreatedindifferently,theyounganimaloftheproperageproceedstoformanemotionalattachmenttowhateverispresentintheenvironmentatthattime.Theessentialmechanismappearstobeaninternalprocessactingontheexternalenvironment.Inthiswayitisindeedquitedifferentfromconditioning,whichisdirectlydependentonoutsidecircumstances.

Thishypothesisfitsmuchoftheexperimentalandobservational


evidence.Tostateitmoreclearly:ayounganimalautomaticallybecomesattachedtoindividualsandobjectswithwhichitcomesintocontactduringthecriticalperiod.Thecapacitytodothisneednotbelostatlaterages,buttheprocesscanbesloweddownorpreventedbythedevelopmentofinterferingbehavior,particularlyfearresponses.Likewise,theprocesscanbepreventedatlateragesbythedeclineofpositivebehaviorwhichnormallybringstheyounganimalintocontactwithothers.

HUMANAPPLICATIONS

Wehavereasonedthatthereisahighprobabilitythatacriticalperiodforprimarysocializationexistsinhumandevelopment.However,thisconclusioncanbeverifiedonlybydirectobservationandexperimentonhumaninfants.One

canbeverifiedonlybydirectobservationandexperimentonhumaninfants.Oneresultisthefindingthat,aswepointedoutinthelastchaper,thesequenceofdevelopmentalprocessesinmanandthedogoccurinasomewhatdifferentorder(Table4.6).Theperiodofprimarysocializationinhumaninfantsextendsfromapproximately6weeksto6months,thusprecedingtheperiodoftransitiontotheadultmethodsoffeedingandlocomotionratherthanfollowingit.Thismeansthatthebabycanformitsprimaryrelationshipsonlywiththosepersonswhotakecareofit,asitisunabletomakecontactsonitsown;anditalsomeansthatthefirstandprobablythedeepestrelationshipwillbeformedwiththemotherratherthanwiththefatherorsiblings.Alltheseconclusionsarebasedondescriptiveevidence.Experimentalworkofthekinddonewithloweranimalsisdifficultifnotimpossiblewithbabies,andallwehavetogobyaretheresultsofvariousaccidentsandvariationsinhumanbehavior(Gray,1958).

Therehavebeenafewisolatedcasesofchildrenwhohavebeenconfinedbyparentsorcaretakersinsocialisolationcomparabletothatofapuppyraisedinasmallbox.ThebestknownofthesecasesisthatofKasparHauser,ayouthwhoturnedupinNuremberg,Germanyintheyear1828(SinghandZingg,1939).Noonewasabletoverifywhathisactualpreviousexperiencehadbeen,butheapparentlyhadbeengivenanelementaryeducationwhilekeptincloseconfinementfrombabyhooduntilnearlyanadult.Sincethiswasbeforethedevelopmentofthescienceofpsychology,thereportsconcerninghimweremadebyajudgeratherthanatrainedscientist.Hedescribedtheboyasgoodnaturedandsociallyresponsivebutcompletelynaiveabouttheoutsideworld.Therewasnoevidence

148BEHAVIORPATTERNS

ofunusualfearfulness.Forwhatitisworth,thedescriptionofKasparHauser'sbehaviorsoundssomewhatmorenormalthanthatofpuppiesrearedinisolation.

Wolfchildren.—Deliberatelyfosteringahumanbabyonanotherspeciesiscompletelyimpossiblefromahumanitarianviewpoint,butthereareoccasionalnewsreportsofthisoccurringbyaccident.Thesesomewhatlegendaryaccountsusuallyconcern"wolfchildren"inIndia,andhavebeenfictionalizedbvKiplinginhisjunglebooks,butonesuchreporthasamorescientificbasis.Inthe1920'saReverendSinghwassaidtohavefoundtwo"wolfchildren"inIndiaandbroughtthemtoanorphanage,whereheattemptedtoeducatethem(SinghandZingg,1939).Accordingtohisaccount,hefoundthetwochildrenlivinginawolfdenfromwhichwolvesalsoemerged.This,ofcourse,wouldnotprovethat

wolfdenfromwhichwolvesalsoemerged.This,ofcourse,wouldnotprovethatthechildrenhadbeenrearedbywolvesbutsimplythatwolvesandchildrenwerefoundtogether.OgburnandBose(1959)latermadeanintensiveefforttocheckuponthisstorybutwereabletoverifyverylittleexceptthattherehadactuallybeenaReverendSinghandthattherewerenewspaperstoriesaboutwolfchildrenatthattime.Theaccountsoflivingpersonswhorememberedtheincidentwerehighlycontradictory.

Apartfromthedubiousnatureoftheevidence,thechancesthatahumanbabycouldactuallyberearedbvwolvesaresosmallthatwecandiscountsuchreportsasfantasvunlesssometrainedobserveractuallyseesababybeingmotheredbyawolf.Wolves,likedogs,nursetheiroffspringforapproximately7weeks,afterwhichmilkisnolongeravailable.Asearlyas3weeks,thevbeginfeedingtheiroffspringonvomitedfoodandmeatwhichisoftenpartiallyspoiled,particularlyinwarmclimates.Eveninaprimitivehumansociety,ababyhastobenursedfortwoyearsorsoinordertosurvive,andthereisusuallyahighinfantmortalityratefromintestinalinfections.Itisconceivablethatawolfmightadoptahumanbabybutnotthatthebabycouldsurvivewithonlvwolfcare.

Itissignificantthatthesereportsofwolfchildrencomefromareasofgreatpovertywherechildneglectanddesertionarecommon.Itisquitepossiblethatchildreninsuchareashavebeenabandonedbytheirparentsconsiderablylaterthanearlyinfancyandhavebeenabletosurviveand"runwild."JudgingfromGinsburg'ssuccessinsocializingadultwolves,itwouldevenbepossibleforsuchachildtobeacceptedandtoleratedbywolves.\sscientificevidence,however,thereportsconcerning"wolfchildren"havelittlevaluebecauseitisimpossibletocheekwhatactuallyhappenedtotheml>eforetheywerelouncl.Forwhatitisworth,suchchildrenarereportedtobe


wildandfearful,likethepuppiesraisedentirelyapartfromhumanbeings.

Adoption.—Alessdrastictvpeoffosteringfrequentlytakesplaceinthehumanpracticeofadoption.Foronereasonoranotherbabiesmaybetakenfromtheirnaturalparentsandeitherraisedinorphanagesoradoptedbyotherindividuals.Fromourknowledgeofhumandevelopment,wewouldexpectthatababycouldbetransferredfromoneparenttoanotherduringthefirsttwomonthswithoutthebaby'snoticingwhathadbeendoneaslongasmaternalcarewassufficient.From2to5monthsofage,wewouldexpectthatthebabywouldbeemotionallydisturbedbythechangebutwouldmakearelativelyeasyadjustmenttothenew

disturbedbythechangebutwouldmakearelativelyeasyadjustmenttothenewparent,justaspuppiesseemtododuringtheperiodofprimarysocialization.Beyondthisagethebabywouldhaveformeddefiniterelationshipswhichwouldbebrokenoffwithconsiderableemotionaldisturbance,makingadoptionmoredifficult,bothbecausethebabywouldnotreadilyformnewrelationshipswithstrangersandbecausethefosterparentswouldbeupsetbytheemotionalbehayiorofthechild.

Theactualstudiesofadoptedchildrenarenotimpressiyeasscientificexperiments,butpeoplewhoworkwithchildrenagreeontwothings.Oneisthatchildrenadoptedbefore6monthsofagegetalongbetterthanothers,andtheotheristhatprolongedexperienceinanorphanageproducesbadresultsonmanychildren.Anotherconclusionisthattheresultsarenotalwaysbad,sincemanychildrenturnoutwellinspiteoftheseearlycircumstances.Thisyariation,ofcourse,couldbecausedbydifferencesingeneticconstitutionoftheindiyidualsinvolved.Somechildrenmaybemoreresistanttoemotionaldistress.

Anotherkindof"accidentalexperiment"isproducedbyhospitalizationofveryyoungchildren.Herethebabymaybetakenawayfromitsparentssuddenlyandputwithstrangersfordaysorweeks.Inaddition,itmaybesufferingfromillnessandphysicalpaininthesestrangesurroundings.Bowlby(1951)andothershavefoundthatsuchchildrenshowevervevidenceofsevereemotionaldisturbanceatthetime,despiteeffortsbvnursestokeepthemreasonablycomfortableandhappv.Bowlbvalsofound,workingintheotherdirection,thatmaladjustedchildrenfrequentlyhadsufferedsuchdrasticearlvexperiences.Heconcludedthatsuchchildrenweresometimesunabletodevelopdeepemotionalrelationshipsinlaterlife.Iftrue,thiswouldmeanthattheprocessofsocializationhadbeendefinitelydisturbed.

Lookingattheseexperiencesinanotherway,wecanseethatfor

ayoungsocialmammallivingundernaturalconditions,asituationinwhichitisseparatedfromitsparentsinstrangesurroundingsisacutelydangerous.Suchananimalwouldbeunlikelytosurviveunlessitgaveastrongemotionalreactionwhichmightattracttheattentionofitsparents.Youngpuppiescertainlyreactinthisway,anditmayalsobetrueofbabies.Whyaprolongedseparationandtheresultingemotionaldisturbancewoulddisturbtherelationshipbetweenmotherandchildisamatterofconjecture,butwecansupposethatababymightconcludeinaprimitivewaythattheparentsthemselveswerethecauseofhisemotionaldiscomfortandanticipatethattheymightabandonhimagainandproducethesamepainfulfeeling.

producethesamepainfulfeeling.

Theseare,ofcourse,humanphenomenaintowhichsubjectivereactionsalwaysenter.Ouranimalexperimentsdogivesupporttocurrentideasregardingthedesirabilityofearlyadoptionandthekeepingofchildreninfamiliesratherthaninorphanages.Lateadoptionis,ofcourse,stilltheonlypracticalcourseofactioninmanycases,butitmustbedonewithagreatdealofcareandpatience,includingtherealizationthattheformationofanemotionalattachmentbytheolderchildwillbeamuchslowerandlessautomaticresponsethaninayounginfant.Byaddingtoourunderstandingofthebehavioralmechanisminvolvedinprimarysocializationandadoption,theanimalexperimentsalsosuggestwaysinwhichpsychologicaldamagemaybeavoidedwhenchildrenareplacedinsuchdifficultsituationsbyaccidentornecessity.

THEDEVELOPMENTOFSOCIALRELATIONSHIPS

INTRODUCTION

Asocialrelationshipmaybedefinedasregularandpredictablebehavioroccurringbetweentwoormoreindividuals.Thisdefinitionappliesnotonlytorelationshipsinanimalsocietiesbuttothoseinhumansocietiesaswell,whererelationshipsystemsformafundamentaltypeofsocialorganization.Inhumansocietiesarelationshipbetweentworelativessuchasfatherandsonconsistsofboththeobservedbehaviorbetweenthemandasystemofverbalruleswhichmayormaynotcorrespondtotheactualbehavior.Inananimalsocietytheverbalelementis,ofcourse,missing.

Psychologicaloriginofarelationship.—Whentwopuppiesmeetforthefirsttime,eachrepresentsaproblemtotheother.Ifonepuppyinitiatesplayfulfighting,willtheotherrespondinkind,orbypassivesubmission,orbyrunningaway?Atthefirstmeetingthepuppiesmaytryoutavarietyofsolutionstotheproblem.Withsubsequentexperience,theyworkoutsomesortofsolution,oftenonabasisoftrialanderror,andbegintoreduceittoahabit,omittingmuchoftheoriginalbehavior.Thusasocialrelationshipbeginsasaproblemandendsasasimplehabit.

Fromwhatweknowaboutlearningandhabitformation,wecanpredictthathabitsarenotinvariable;infact,thereisanormaltendencyforananimaltovaryitsbehavioreveninwhatappeartobeidenticalsituations.Thisis,ofcourse,anessentialpartoftheprocessoflearning,forwithoutitnoimprovementofadaptationwouldbepossible.Theamountofvariationisreducedinfrequently

adaptationwouldbepossible.Theamountofvariationisreducedinfrequentlyrepeatedbehaviorbutneverentirelyeliminated.Wealsoknowthathabits

151

152BEHAVIORPATTERNS

arenotunbreakable.Ahabitwhichonceledtosuccessfuladjustment,butnolongerdoesso,mayberepeatedforashortwhilebutsoondiesout.Thereforeasocialrelationshipisneitherinvariable,norincapableofchange.However,socialrelationshipsundertheproperconditionscanbecomeextremelystableandinvariable.

Thedifferentiationofbehavior.—Whenweapplytheideaofdevelopmenttosocialrelationships,wecanseethattherearetwokindsofdevelopment.Oneistherapidpsychologicaldevelopmentofarelationshipwhichmayoccurwithinafewdaysorevenhours,andtheotheristhelong-termbiologicaldevelopmentofarelationshipbasedontheslowerprocessesofgrowthandbiologicalchange.Thesetwokindsofdevelopmentmaybothbedescribedintermsofdifferentiationofbehavior.Inarelationshipbasedonplayfulfighting,twopuppiesatfirstshowmuchthesamekindofbehavior.Attheendoftherelationship,onemayalwaysattackandtheotheronealwayssubmit;theirbehaviorisnowdifferentiatedonapsychologicalbasis,andtheprocessoflearningmayresultinaveryslightoraveryhighdegreeofdifferentiation.

Thispsychologicalprocessisalsoaffectedbytheothertypeofdifferentiationofbehavior.Anewbornpuppyhasrelativelyfewalternatebehaviorpatterns.Asitgrowsolder,thecapacitiesforawidervarietyofbehaviorpatternsappear.Whereasatfirstthepuppycouldonlyyelpinresponsetodiscomfort,itcannowrunawayorattackthesourceofdiscomfortaswellasvocalizing.Thusthepuppydevelopsthroughbiologicalprocessesthecapabilitytodifferentiateitsbehaviorindifferentsituations.

Morethanthis,geneticfactorsdifferentiatethebehaviorofoneindividualfromanother.Insocialmammalstherearebasicdifferencesinbehavioralcapacitiesbetweenmalesandfemalesandbetweenadultsandyoung.Withineachofthesemaintypes,individualsmaybeaffectedbydifferentialheredityandsoshowdifferentkindsofbehavior.Itistheimportanceofthelatterphenomenonwithwhichthischapterismainlyconcerned.

Fundamentalclassificationofsocialrelationships,—Inhisfieldstudiesof

Fundamentalclassificationofsocialrelationships,—Inhisfieldstudiesofprimates,Carpenter(1934)developedaclassificationofobservedrelationships.Withthreetypesofindividuals—males,females,andyoung—itispossibletohavethreerelationshipsbetweendifferentkindsofindividuals(male-female,male-young,andfemale-young)andthreemorebetweenthesamekindsofindividuals(male-male,female-female,andyoung-young).Inthecaseofthedog,whichregularlyFormsrelationshipswithhumanbeings,sixbasickindsofindividualsarcinvolved.Thismeansthattherearefifteenrelation-

SOCIALRELATIONSHIPS

153

shipspossiblebetweendifferentkindsofindividualsandsixbetweenliketypes,makingatotaloftwenty-one(seeTable6.1).

TABLE6.1

SocialRelationships*ofDogandMan

•Thereare21possiblerelationships,usingallcombinationsofageandsex:9dog-humanrelationships(loweJleftcorneroftable)and6eachofdog-dogandhuman-humancombinations(upperleftandlowerrightcorners).

Inourexperiment,therelationshipsformedwerelimitedbythesystemofrearing.Amongdogs,onlytworelationshipswerestudiedseriously,thosebetweenmotherandyoungandthosebetweenyoungbelongingtothesamelitter.Thedog-humanrelationshipswerelikewiselimited.Sinceourexperimenterswerealladults,thechiefrelationshipsstudiedwerethehumanmaleversusyoungdogandhumanfemaleversusyoungdog.

Analysisofsocialrelationships.—Sinceitisdefinedasthebehaviorexhibitedbytwoindividuals,asocialrelationshipsuchasthatbetweenmotherandoffspringmustconsistofbehaviorpatternsbelongingtooneormoreofthenineimportantsystemsofbehaviordescribedinchapter3.Thismakesitpossibletoanalyzeintovarioussortsofbehavioraladjustmentstherelationshipexistingbetweenanytwoindividuals.Sincethereareninesystemsofbehavior,therearelikewiseninepossiblerelationshipsinwhichbothindividualsexhibitthesamepatternsofbehavior.Iftwoindividualsrespondtoeachotherwithunliketypesofbehavior,atotalofthirty-sixmorerelationshipsarepossible.Inactualpracticeonlyafewofthesetheoreticalrelationshipsappeartobeimportantin

practiceonlyafewofthesetheoreticalrelationshipsappeartobeimportantinanyonespecies(Scott,19536).

Inthemother-offspringrelationshipsofdogs,thepredominantbehaviorofthemotherisepimeletic.Thepuppiesexhibitet-epi-meleticbehavior(whiningandyelpingwhenindistress),ingestivebehavior,andeliminativebehavior.Wecancallthistypeofrelationshipcare-dependency.Otherkindsofrelationshipsmaybedevelopedasthepuppiesgrowolder.Intheprocessofweaning,the

motherkeepsthepuppiesfromnursingbygrowlingandthreateningthem,thusestablishingadominance-subordinationrelationship.Othersystemsofbehaviorareexhibitedbythemotherbuthaverelativelylittleimportance.Sincethemothercomestofeedthepuppieswhiletheyremaininoneplace,thereislittleopportunityforaleader-followerrelationshiptodevelopbetweenthem,andthemotherusuallydiscouragesanyattemptsatsexualplayonthepartofthepuppies.

Themostimportantrelationshipbetweenlittermatesisbasedonagonisticbehavior.Thepuppiesgraduallydevelopdominance-subordinationrelationshipswhicharemainlyconcernedwiththedistributionoffoodbutwhichmayalsoaffectthedistancebetweenindividualsastheyoccupytheirlivingspace.Thepuppiesinalittershowagreatdealofallelomimeticbehaviorwithmutualfollowing,butthereislittleornoindicationofimportantleader-followerrelationships.Usually,thefirstpuppytonoticeastrangeobjectwillruntowarditandtherestwillfollow,andwhichpuppyinitiatessuchamovementisamatterofchance.Asforsexualbehavior,whilepuppiesexhibitmuchplayfulbehaviorofthissort,thedevelopmentofadultsexualrelationshipswasnotpermittedbythedesignofourexperiment.Puppiesdoverylittlegroomingeitherofthemselvesoreachothersothatthemutualcarerelationshipseeninprimateshaslittleimportance.Thepuppieshavethecapacityfordevelopingmutualdefenseandcoordinated-attackrelationshipsbutagaintheconditionsofrearingpreventedthisfromdeveloping,sincecontactswithstrangerswerenotpermitted.

Asmightbeexpectedinaschoolfordogs,thedog-humanrelationshipismorecomplex.Thehumanhandlersandcaretakerstakeoverthecare-dependencyrelationshipfromthemotherdogandmaintainitthroughoutthelivesofthepuppies,sothatinthisrelationshipthedomesticdogneverbecomesanadult.Likewise,thehumanhandlersdevelopadominance-subordinationrelationshipwiththepuppiesinwhichthehandlerisalwaysdominant.Bymeansofvarious

withthepuppiesinwhichthehandlerisalwaysdominant.Bymeansofvariouscontrolmethodsthehandlersalsodevelopsomethingofaleader-followerrelationshipwiththepuppies.

Socialcontrol.—Anysocialrelationshipcanbeanalyzedintermsofcontrol.Inmostrelationships,theanimalsobviouslycontroleachotherandtheconceptbecomesimportantonlvwhencontrolisunequal,asitisinadominance-subordinationrelationshiporaleader-followerrelationship.Thedog-humanrelationshipiscomplicatedbydeliberateattemptstoextendandincreasetheamountofsocialcontrol.Twodevicesareimportant:oneisanextensionofthecare-

dependencyrelationshipinwhichthedog'sfoodismadeconditionalonhisperformingcertainactions,andtheotherisanextensionofthedominance-subordinationrelationshipinwhichthedogisforcedtoperformcertainactssuchasfollowingonaleashorsitting.Asmanyobservantwritershavepointedout,thesemethodsareverysimilartothoseonceemployedinhumanslavery.Fromapsychologicalviewpointtheycanbecalledrewardtrainingandforcedtraining.Ineithercasethebalanceofcontrolisshiftedstronglytowardthehumanmemberoftherelationship.

Oneoftheobviousfeaturesofthedog-humanrelationshipisitsmanyresemblancestothehumanparent-childrelationship.Itsdevelopmentthereforebringstheelementalproblemsofchildpsychologyintosharpfocus.Thesuccessesandmistakesofparentswiththeirchildrenareclearlymirroredinthereactionsofyoungpuppiestotheirhandlers.

THEDEVELOPMENTOFDOMINANCERELATIONSHIPSBETWEENLITTERMATES

Thedominancetest.—Wedeliberatelysetupourconditionsofrearingsoastominimizecompetition.Ourpuppieswerefedondryfoodandmilk.Dogsneverfightoverthepossessionofliquidsandseldomattempttodefendafeedingdishinwhichdrydogfoodisalwayspresent.Inordertostudythedevelopmentofdominance,wethereforehadtointroduceacompetitivesituationwhichwecouldcontrolandobserve.From2until10weeksofageeachlitterwasgivenaweeklydominancetrainingperiod.Themotherwasremovedandasingleboneplacedinthepenfor10minutes,duringwhichtimethereactionsofthepuppieswererecorded.

Unlikeliquidanddrydogfood,afreshboneisastrongstimulustoagonistic

Unlikeliquidanddrydogfood,afreshboneisastrongstimulustoagonisticbehavior.Evenpuppiesof2weeksofagewillaccasion-allygrowlandbarkwhengivenameat-coveredbone.Thisisoneofthefewcasesindogsofaspecificprimarystimulusproducingabehaviorpatternandissimilartothemanycasesof"releasers"inbirds.

Asthepuppiesgrewolder,therewasmoreandmorecompetitionoverthebone,andoccasionalfightsbrokeout.At5weeksofagewegaveadetaileddominancetestinsteadoftheusualtrainingperiodandrepeatedthisat11and15weeksofage.

Inthedominancetestallthepuppiesweretakenoutofthepenandbroughtback,onepairatatime.Whentheyhadquieteddown,asinglebonewasbroughtin,showntobothpuppies,andlaidbe-

tweenthem.Anobserverthenrecordedthebehaviorofbothpuppiesfor10minutes,timingthepossessionofthebonebyeachpuppyandnotingtheoccurrenceofgrowls,barks,attacks,andotheritemsofagonisticbehavior.

Alldegreesofdominanceappearedintheinteractionsbetweenthepuppies.Veryrarely,twopuppieswouldsharethebone.Othersappearedtotaketurns;i.e.,aslongasapuppyheldthebonehewasdominant.Stillothersstruggledwitheachothercontinually,andinsomepairsonepuppywouldimmediatelyseizetheboneandholditfortheentire10-minuteperiod.Wedecidedtodefinedominancearbitrarilyasaconditioninwhichonepuppykepttheboneforatleast8outof10minutes.Inordertoprovethatthiswasrealdominanceandnotasituationinwhichthepuppywasallowedtokeepthebonesimplvbecausehegotitfirst,wemadeachecktestattheendoftheperiodbytakingtheboneawayandgivingittotheapparentlysubordinatememberofthepair.Ifthesubordinateanimalcouldkeepit,wesaidthatthefirstanimalwasincompletelvdominant.Ifthebonewastakenaway,wesaidthatthefirstpuppywascompletelydominant.Inshort,wedefinedacompletelydominantanimalasonethatkeptpossessionofthebonethemajorityofthetimeandwasabletorepossessitatwill.

Theresultsshowedthatlittledominancehadbeendevelopedat5weeks.Notmorethan25percentofthetestsshowedcompletedominanceinanybreedatthisage.Bv11weeks,allbreedsshowedalargeincreaseinthenumberofcompletelydominantrelationships.Beyondthispointonlvthewire-hairedterriersshowedacontinuingincrease,althoughthebasenjisandsheltiesshowedanincreasebetween15weeksandoneyear(seeFig.6-1).

Itwasobviousthatthedominanceteststhemselvesservedastrainingperiodsforthedevelopmentofdominancesinceactualfightsoccurredinmany.Thewinningpuppvafterwardsbecamedominantovertheloser.Wealsosawoccasionalfightsamongpuppiesatothertimes,arisingfromundeterminedcauses.Again,thewinnerofthefighttendedtobecomedominantinthefuture.Itshouldbeaddedthatthesefightsbetweenvoungpuppiesweremostlyamatterofnoiseandstruggle,withverylittleactualdamageinflicted.Thusdominancewassettledearlyindevelopmentbeforeadultcapacitiesformoreseriousfightinghadappeared.

Effectofdominanceontheamountoffighting.—Itisoftenstatedthatthedevelopmentofadominanceorderhastheeffectofdecreasingthetotalamountoffighting,sinceonceadefiniterelationshipissetupthereisnolongeranyneedforfights.Inmostofthebreeds

SOCIALRELATIONSHIPS

157

therewasnotenoughobservedfightingsothatrelativepercentagesatdifferentagescouldbeaccuratelycalculated.However,inthebasenjibreed,fightingwasfairlyfrequentandsomeconclusionscanbedrawn(Fig.6.2).Thetotalamountoffightingincreaseswithage,butthisdoesnotholdforallrelationships.Althoughitistruethatfightsbetweenmalesaremuchmorefrequentatoneyearofage,presumablyasaresultofsexualmaturity,thepercentageoftestsinwhichactualfightsoccurbetweenfemales,orbetweenmalesandfemales,remainsconstantbetween10and20percentatany

5II15

AGEINWEEKS

Fig.6.1.—Percentageofoccurrenceofcompletedominanceinlittersofpurebreddogs.

age.Thus,inthisparticularbreed,thedevelopmentofdominanceorganizationseemstokeepfightingataconstantlevel,ratherthandecreasingit,andisunabletosuppressfightingbetweenmalesatsexualmaturity.Ofcourse,wehavenofiguresontheamountoffightingwhichmighttakeplacebetweenstrangepuppiesnotaffectedbyadominanceorder,andthiswouldprobablyshowamuchhigherfigure.

Inaddition,inbothmale-femaleandfemale-femalerelationships,thenumberofattacks(inwhichoneanimalassaultsanotherthatdoesnotfightback)tendstoriseafter11weeksofage.Thenumberofattacksofonemalebasenjionanotherishigherat11and15weeks

BEHAVIORPATTERNS

ofagebutdecreasesatoneyear,probablybecausetheseattacksarenowresultinginactualfightsandareenteredassuchontherecords.Thismeansthatfightingbythedominantanimalisnotsuppressedandmayincreasesomewhat.Nevertheless,thetotalamountoffightingisprobablymuchlessthanitwouldbeifthesubordinateanimalsfoughtback.

20

5■

UJ

(j

LUQ.

^

15--FIGHT

10-■

BASENJI

ATTACKS

20

15

î-

52

15-•

10

ATTACKS

SHELTIE

FIGHTSN

fc*

II1552

WEEKS

Fig.6.2.—Occurrenceoffightsorone-sidedattacksduringdominancetests.

InShetlandsheepdogsdieresultsaremuchclosertowhatwewouldexpect(Fig.6.2).Therearcmorefightsandattacksat5weeksofagethanatanyothertime.Also,at5weeksofage,there

aremoreattacksinmale-femalepairsthananyothercombination,thisnumberbeingdecreasedtozeroat11weeksofage.

Inthefoxterrierbreedthereweresofewfightsorattacksatanyagethatnopercentagescouldbecalculated.Thisisthebreedinwhichthemostcompletedominanceisseen.Whenseriousfightingbrokeoutinthisbreed,itwasalmostneverbetweenpairsbutinvolvedgroupattacksononeindividual,andthese,ofcourse,couldnottakeplaceinthepaireddominancetests.Intheothertwobreeds,beaglesandcockerspaniels,therewerelikewisealmostnoobservedfights,notbecauseofarigiddominanceorder,butbecausethesebreedshaveaverylowdegreeofaggressiveness.

Thus,thetheoryofthedominanceorderasacontrollingagentinfightingisupheldintwobreeds,foxterriersandshelties,butnotinanother,thebasenjis.Thisfindingmaybepartiallyexplainedbythefactthatthebasenjishaveseasonalbreedingandconsequentlymoresuddenchangesinthelevelofthemalehormoneastheyapproachmaturity.However,thereisalsomorefightinginthisbreedatyoungerages,anditispossiblethatallthisistheresultofforminglessrigidhabitsofdominanceandsubordination.Atanyrate,thereseemtobedefinitebreeddifferencesinthecapacitytodevelopaneffectivecontrolsystemoverfightsbetweenindividuals.

Theeffectofbreedondominanceorganization.—Knowingthatthebreedshavebeenselectedfordifferencesinaggressiveness,wewouldexpectthatthedevelopmentofdominancerelationshipsmightshowlargedifferencesbetweenbreeds,andthisisindeedthecase.

Inwire-hairedfoxterriers,thenumberofdominancerelationshipswasgreatlyreducedafter5weeksofagebythegroupattackswhichledtotheseparationofanimalsfromtheirlitters.However,thepercentageoftestswhichresultedincompletedominancecontinuedtorise(Fig.6.1).Whenwe(PawlowskiandScott,1956)analyzedthisrise,wefoundthatitconsistedalmostentirelyofmale-femalerelationshipsandthatmoreandmoremaleswerebecomingcompletelydominantovertheirsisters(Fig.6.3).

completelydominantovertheirsisters(Fig.6.3).

Thebasenjisshowedadifferentpicture.Thetotalnumberofcompletedominancerelationshipsrosebetween5and11weeksbutstayedatalmostthesamelevelat15,thenrosesharplyagainatoneyear.Thefightingbehaviorofthebasenjithustendstoappearinlaterdevelopment,ratherthaninearlypuppyhoodasitdoesinthewire-hairedfoxterriers.Thedominanceofmalesoverfemalesshowedthesamesteadyriseasinthewire-hairedterriers,andatoneyearnofemaleswerecompletelydominantovermales.

II15

WEEKS

5II1552

WEEKS

WEEKS

Fig.6.3.—Occurrenceofcompletedominanceinmale-femalepairs.

WEEKS

WEEKS

Fig.6.3.—Continued.

BEHAVIORPATTERNS

100

II15

WEEKS

Fig.6.3.—Continued.

Beaglesandcockerspanielswerequitesimilarintheirdevelopmentofdominancerelationships.Therewasarisebetween5and11weeksandaslightdeclineafterthattime,continuinguntiloneyear.Asadults,bothcockersandbeagleswerelikelytobeindifferenttopossessionoftheboneandtopayattentionsolelytotheobserver,sothatnodominancestatuscouldbedetermined.Furthermore,thesetwobreedswereverydifferentfromtheotherswithrespecttomale-femaledominance.Thereislittleindicationthatmoremalesaredominantthanfemales,andifanything,thereisaslightdifferenceinfavorofthefemalesbyoneyearofage.

Shetlandsheepdogs,likebeaglesandcockers,showedalargenumberofcasesofincompletedominanceandparticularlyofcaseswherenodominancecouldbedetermined.Themajorityofthelattercasesturnedouttobebetweenmalesandfemales.Inasmallsampleof11male-femalepairs,thereweretwocasesinwhichthefemalewasdominant,threecasesinwhichamalewasdominant,andsixinwhichtherewasnodominance.Thisisquitedifferentfromtheotherbreeds.Incockersandbeaglestherearemorecasesofcompletedominancebetweenmalesandfemalesthanbetweenlikesexes,andinbasenjisandfoxterriersthereisastrongtendencyformalestodominatefemales.Thesheltiestendnottodominatefemalesinconflictsoverfood.

Thisbreeddifferencemayreflectacharacteristicoftheshelties,

Thisbreeddifferencemayreflectacharacteristicoftheshelties,

SOCIALRELATIONSHIPS163

whoarerelatedtotheScottishcollies.InthestoriesofAlfredPaysonTerhunetherearemanyreferencestothe"chivalry"ofthemalecollietowardthefemale.Certainlyweobservednothingofthekindinthepuppiesoffourofourfivebreeds,butthesheltiesmaybeanexception.However,theseresultswithcompetitionoverabonedonottellthewholestoryofthedominancerelationshipsinthisbreed.Asobservedintheirlargeoutsidepens,thesheltiesdevelopedastrongdominanceorderbasedonspace.Wheneveranobservercamenear,theentirelitterwouldrushoutandstarttobark,butalmostimmediatelytwoorthreeoftheanimalswouldturnontheirlittermatesanddrivethembacktowardtheirhouse,wherethefoodandwaterwerekept.Inonelitter,onefemalecouldneveremergefromthehousewithoutgettingchasedandbarkedat.Asmallmalewasallowedtositoutsidethehouse,whiletwolargemalescouldrunupanddownthepen,barkingfreely.Inshort,thereappearedtobeastrongdominanceorderbasedonspaceratherthanfood,withnodeferencepaidtotheweakersex.Basenjis,ontheotherhand,seemedtobecompletelytolerantofoneanotherwithrespecttospace.Agroupwouldsitpeaceablyorrunsidebysidewithoutinterference,butcompetefiercelyassoonasfoodwasbroughtintothepen.Inaseparateexperiment,inwhichbasenjisweregivenspecialfoodinadish,thedominantmemberimmediatelytookchargeofthedishandwouldallownoneoftheotherstoeat.Oneofthesubordinateanimalsdevelopedthetechniqueofrushinginwhenthedominantanimal'sbackwasturnedandtippingoverthedish.Hewasthenallowedtoeatthefoodspilledontheground,butnotoutofthedishitself.

Suchdifferencesinbehaviorindicatethatdominancehierarchiesarenotuniversalbutaredevelopedinspecifickindsofsituations.Whetheritwouldbepossibleforadogtooccupyadifferentpositioninahierarchyundertwodifferentsituationsisaquestiononwhichwehavenoevidence.

Thebreeddifferencesarealsocomplex.Thefourhuntingbreedsareallstronglymotivatedbyfoodbutdiffergreatlyinaggressiveness,thebeaglesandcockerspanielsbeingmuchmorepeacefulanimals.Theshelties,ontheotherhand,appeartohavearatherhighdegreeofaggressivenessbutarerelativelylittlemotivatedbyfood,sothattheysimplydonotcompetestronglyforitspossession.Therehasundoubtedlybeenselectioninthisbreedforthelackoffoodmotivationwhichwouldbelikelytointerferewiththeirtrainingasworkingdogs.

dogs.

Geneticeffectsonthedominanceorganizationoftheentiregroup.—Thekindoftestdescribedabovedoesnotreflecttheeffectof

BEHAVIORPATTERNS

severalmembersofagroupuponeachother.However,wecanexpressthetotalorganizationintermsofrelationshipsbetweenindividualpairs.Whenwedothis,wefindthatthereisagreatertendencyintheaggressivebreedstodevelopastraight-linedominancehierarchywitheachanimaldominantoverthoseinthelowrerranks.Inthelessaggressivebreeds,adominancediagramhasasprawlingappearancewithseveralindividualsinthesamerank,althoughwegetfew,ifany,casesofthecirculardiagramswhichsometimesoccurinflocksofchickens.

Theeffectsofsexandsize.—Withrespecttosex,wehadthreekindsofrelationshipsinourexperiment:male-male,female-female,andmale-female.Whenmalesandfemalesmeteachotherthemalestendedtodominate,particularlyincasesofcompletedominance.Also,thereweremorecasesofcompletedominancebetweenmalesandfemalesthantherewerebetweenlikesexes,eithermalesorfemales.Thisreflectsthefactthatmalesareontheaveragelargerandmoreaggressivethanfemales.

Table6.2summarizestheresultsofathoroughanalysisoftheeffectofsizeondominanceat15weeksofage.Thereisnoindicationthatsizehasanyeffectonthedominanceexistingbetweenfemalepairs,eveninpairswhichshowedlargedifferencesinweight.Inthemalepairs,heavieranimalstendedtobedominant,providedtherewasadifferenceofatleast1kilogram.Thiseffectismorestrikinginthehybridsthaninthepurebreds,butifallhybridsandpurebreds

TABLE6.2

EffectofSizeon-Dominance-SubordinationRelationships(HybridsandPureBreedsCombined)

9P<.05••P<.01


areaddedtogether,thedifferencebetweentheactualfiguresandthosewhich

areaddedtogether,thedifferencebetweentheactualfiguresandthosewhichwouldbeexpectediftherewerenoeffectofsizeisstatisticallysignificantatthe.03level.Withregardtothemale-femalecontests,thereisauniformtendencyforheavieranimalstobedominantinaratioofatleast2to1,butthis,ofcourse,reflectsboththeheavierweightandgreateraggressivenessofmales.

Thisdifferenceindominancerelationsdevelopedbythetwosexesiseasilyexplainablebytheobserveddifferencesinbehavior.Femalesrarelygetintoactualfightswitheachotherandseemtoestablishdominancelargelyonthebasisofvocalizationandthreats.Ontheotherhand,malesoftengetintorealfights,inwhichsuperiorsizeis,ofcourse,importantindeterminingtheoutcome.Similarly,malesarelikelytomakeactualattacksonfemalesratherthanbeingintimidatedbybluff,andtheresultisusuallydominancebythemale,particularlyinthemoreaggressivebasenjiandfoxterrierbreeds.Incontestsbetweenmalesandfemales,thesuperiorsizeofthemalesaswellastheirgreateraggressivenessundoubtedlyplaysapartintheoutcome.

Geneticsandthedifferentiationofbehavior.—Themostimportantconclusionfromtheaboveresultsisthatwegetextremedifferentiationbetweenthebehavioroftwoindividualsinvolvedinarelationshiponlywheretherearelargedifferencesinthecapacitiesofthetwoindividuals,astherearebetweenmaleandfemalepuppies.Morethanthis,bothindividualsmusthavethebasiccapacitytodevelopinadifferentialway.Forexample,beaglesdonotseemtopossessthecapacitytobecomehighlyaggressiveinanyofthecircumstanceswhichwestudied.Iftheabovegeneralizationiscorrect,wewouldexpecttogetgreaterdifferentiationbetweenlike-sexedpairsinsegregatinghybrids(F2'sandbackcrosses)thanwewouldinnon-segregatinghybrids(Fi's)orinpurebreeds,andourexperimentongeneticsandbehaviorprovidesagoodtestofthehypothesis.

AsTable6.3shows,thisexpectationiswellborneoutbythedata.Notonlyarethelike-sexedpairsmoregreatlydifferentiatedinthesegregatinghybrids,butalsothemale-femalepairs.ThebestcomparisonisbetweentheFihybridsandthesegregatinghybrids,andthereisalargerproportionofpairsshowingcompletedominanceineverysegregatinghybridpopulation.Thesameistruewhenthesegregatinghybridsarecomparedwiththepureparentbreeds,exceptforthefemalebasenjis,whichshowslightlygreaterdifferentiationthandothecockerbackcrossesortheF2's.Wemayconcludethatthedifferentiationofasocialrelationshipisproportionaltothedifferenceinbasiccapacitiesofthetwoindividualsconcerned.

BEHAVIORPATTERNS

TABLE6.3

PercentageofCompleteDominanceinBasenjis,Cockers,andTheirHybridsat15Weeks

*P<.05**P<-01

Oneofthebasicreasonsforstudyinggeneticsandbehavioristofindoutjusthowimportantgeneticdifferencesinbehavioralcapacitiesmaybe.Inmanyinstancestheseseemtohavelittleimportanceincomparisontotheeffectsofenvironmentalfactors.Here,inthedevelopmentofsocialrelationships,wehaveacaseinwhichgeneticfactorsarehighlyimportantdeterminantsofbehavior.Thisdoesnotexcludeotherdeterminants,ofwhichwehavemanyexamplesevenindogsraisedinauniformenvironment.Inthemother'srelationshiptothepuppy,relativeageisextremelyimportantinthedevelopmentofadominancerelationship,asmothersarealmostinvariablydominantovertheirpuppies,althoughtheydonotalwaysenforcethisincompetitionoverfood.

Inhighlydevelopedrelationshipsthebehavioroftwoindividualsbecomesdifferentiatedwithrespecttoeachother,i.e.,onebecomesdominantandtheothersubordinate.Atthesametime,eachindividualretainsthecapacitytofurtherdifferentiatehisownbehaviorinrelationtootherindividuals.Thesamepuppymayoccasionallythreatenanotherinarelationshipinwhichheisdominantandincompletecontrol,frequentlyattackinarelationshipinwhichdominanceisunsettled,orbeextremelysubmissiveinarelationshipinwhichheissubordinate.Thesameanimalcanthusbecorrectlydescribedasmoderatelyaggressive,extremelyaggressive,orunaggressive.

Whatthenbecomesoftheideaofa"personality"composedofsimplebehaviortraits?Wearelikelytothinkofananimalorpersonasbeinggenerallyaggressiveorgenerallysubmissive.Thisobviouslydoesnotfitthefacts.Ifwewanttocharacterizethebehaviorofanindividual,weshallhavetodoitintermsofhisrelationships,andinanypracticalsituationthismeansselectingandanalyzingthemostimportantandgeneralrelationshipsoutofmanyspecialandminor

ones.

Isitthenpossibletomakeanygeneralizationsaboutanindividual?Wecansay

Isitthenpossibletomakeanygeneralizationsaboutanindividual?Wecansaythatanindividualhasabasiccapacity,butthiscapacitycanonlybedevelopedintermsofrelationships.Oneanswertotheproblemisthatwhiletherearecertainkindsofrelationshipswhicharespecialandcompletelyunique,thereareotherswhichapplytoseveralindividualsandcanbecalledgeneralrelationships.Examplesofthesetwokindsareeasytofindinhumansituations.Achildhasonlyonemother(aspecialrelationship),butseveralaunts,allofwhomaretreatedmoreorlessalike(ageneralrelationship).Ourpuppyexperiment,ontheotherhand,wassetuptodevelopsocialrelationshipswithasmallgroupofexperimenters,allofwhomattemptedtoactalike.Aswillbeseenfromtheresultsoftheobediencetestdescribedinchapter9,thepuppiesevidentlydevelopedageneralrelationshipwithallexperimenters.

Oneanswertothequestionofthegeneralityofbehaviortraitscamefromthefactthatwhenwetookapuppyoutofthepenandthenputhimbackinwiththelittermates,theyfrequentlythreatenedhim,exhibitingconsiderableaggressivebehavior.Thislookedlikeanopportunitytostudythephenomenonofjealousy,astheotherpuppiesappearedtobe"jealous"oftheonewhohadbeenremoved.Dr.TheodoreZahn,avisitinginvestigatoratHamiltonStation,systematicallystudiedthisphenomenoninseverallitters,takingeachpuppyout,returningit,andobservingtheresults.Hesoonfoundthatrightingwasconfinedtocertainindividualsineachlitter,observingonly10casesofdominancein61relationships.Whenhecomparedhisresultswiththoseofthedominancetestoverbones,hefoundthatmostoftheanimalswhichthreatenedeachotherhadnotpreviouslyshownconsistentdominance.Inotherwords,themanifestationof"jealousy"reflectedthefactthatcertainanimalshadnotestablishedadefinitedominancerelationshipbetweenthemselves.

InanothersortofexperimentKing(1954)placedlittersofadultbasenjisandcockersinlargefieldsandobservedtheirreactiontotheintroductionofstrangeanimals,uptothepointwhenseriousfightingbegantotakeplace.Whenheanalyzedhisdata,hefoundthatthedogswereexhibitingmostaggressivenesstowardanimalslikethemselves.Femalecockersattackedstrangefemalesmoreoftenthantheydidstrangemalesandattackedstrangecockersmorethantheydidstrangebasenjis.Thisinterestingfindingindicatesthatindogs,atleast,thereisnobasichostilitytowardunlikeindividuals.Iftheyarebasicallyhostile,itistowardstrangersresemblingthemselves.Onepossibleexplanationisthattheyattempttoextendthe

dominancebehaviorwhichtheynormallyexhibitintheirowngrouptoinclude

dominancebehaviorwhichtheynormallyexhibitintheirowngrouptoincludeanimalsoffamiliarappearance,butthatthisgeneralizationislesslikelytowardanimalsshowinganunfamiliarsizeandshape.Thereisalsoatendencytoreacttoanimalsoftheoppositesexthroughsexualratherthanagonisticbehavior.

Mostofourstudiesofsocialrelationshipshavebeendonebetweenthetwomembersofapair,partlybecausethisisprobablythemostimportantkindofrelationship,andpartlybecausethetechniqueisrelativelysimple.Whenonebeginstoexaminerelationshipsintermsofgroupsofthreeindividualsinsteadoftwo,theproblemofanalysisbecomesextremelycomplex.Itis,however,animportanttheoreticalandpracticalquestionwhethertherelationshipbetweentwoindividualsisthesamewhentheyarebothpartofagroup.Instudiesofchickensandgoats,thereiseveryevidencethatindividualpaircompetitionsgivethesameresultasgroupcontests.Intheseanimalsfightingalwaysoccursbetweentwoindividualsandtherearenogroupattacks.Butdogsarecapableofgroupattacksonanindividual,andthesituationheremaybequitedifferent.

Wehavesomeobservationalevidencethatthepresenceofagroupmodifiesthebehaviorofoneindividualtowardanother,inthiscasetowardahumanhandler.Weoftenfoundwhenweenteredadogpenthatsomeanimalscameboldlyforwardandothershungback.Yetwhenwetestedallanimalsinanindividualhandlingtest,wefoundthatsomeoftheapparentlyshyanimalswerestronglyattractedtopeople.Theystoodatthebottomofthedominanceorderamongdogsandwerebeingkeptawayfromthehumanhandlersbythemoredominantmembersofthegroup.Dogbuyersfrequentlyselectpuppiesonthebasisofwhichpuppyinagroupcomesmostboldlyforward.Insodoingtheymaybeselectingforaggressivenessagainstotherdogsaswellasagainstshynessofpeople.

Moreobjectivedataonthispointwereobtainedbymeasuringthecatchingtimeofindividualsinagroupduringtheweeklyinspection.Whenwecomparedthesetimeswithattractionscoresinthehandlingtest,wefoundarelativelylowcorrelation.Outof22littersanalyzed(2eachfromallbreedsandhybrids),16showedapositiverank-ordercorrelation,withanaverageRof.30.

Inconclusion,theexpressionofbehaviorinasocialrelationshipisahighlycomplexexpressionofgeneticdifferenceswhoseactionisdependentuponthedevelopmentofbehaviorbetweentwoindividualswhomutuallyaffecteachother.Neverthelesswecanexpresstheresultsasagenerallaw:arelationshiptendstobedifferentiatedinproportiontothedifferentialbiologicalcapacitiesofthetwoindi-

thetwoindi-


victualsinvolved.Themostimportantofthesebiologicalcapacitiesaredeterminedbysex(whichis,ofcourse,hereditary),byindividualheredity,andbyage(whichreflectsbiologicaldevelopment).Allofthesedeterminetheprocessofpsychologicaldifferentiationofbehaviorwhicheventuallyfreezesarelationshipintoarelativelystableform.

Thisgeneralizationneedstobewidelytestedinordertobefirmlyestablished.Assumingthatitiscorrect,allsortsofpracticalapplicationsimmediatelysuggestthemselves.Ifwedesireahighlydifferentiatedrelationship,asinaleader-followerrelationship,thisshouldberelativelyeasytoestablishbetweenquiteunlikeindividuals,asbetweenolderandyoungerpersons.Itwouldbemostdifficulttoestablishleadershipwithinagroupoflikeageandsex,wheretheonlybasicdifferentiationwouldbethatbetweenindividualshavingmarkedlydifferentheredity.Itisnowonderthatpeoplelookingataboys'grouparelikelytoconcludethatoneofthemisa"natural"leader,sinceheredityisalmosttheonlywayinwhichoneboy'sbehaviorcouldbedifferentiatedfromtherest.Ontheotherhand,itisalsopossiblethathisbehaviorcouldhavebeendifferentiatedbyunusualprevioustraining.Thislastquestionhasnotbeenansweredbyourdogexperiment,inwhichearlyenvironmentwaskeptuniform.Experimentswithinbredmiceinwhichhereditywaskeptconstantbutcertainindividualsweregivenpre-traininginfightingshowthatarelationshipcanalsobedeterminedbydifferentialtraining(Scott,1944).Ifwewanttomakeourgeneralizationmoreuniversal,wemustaddthefactorofdifferentialdevelopmentofcapacitiesbytrainingandpreviousexperience.

THEMOTHER-OFFSPRINGRELATIONSHIP

Fromthedescriptionofdevelopmentinthepreviouschapterweconcludedthatthepuppywasincapableofforminganytruesocialrelationshipuntilapproximately3weeksofage.Thisconclusiondoesnotapplytothemother,whocanbegintoformrelationshipsassoonasthepuppiesareborn.Thusthemother-offspringrelationshipisextremelyone-sidedinthefirstfewweeksafterbirth.Furthermore,sincethemotherpaysthegreatestamountofattentiontothepuppiesinthesefirstfewweeksandbeginstoleavethemmoreandmoreastheygrowolder,theeventualrelationshipofpuppiestotheirmotherisweakerthanthatformedwiththeirlittermates.

Thegeneralbehaviorofthemothertowardherpuppiesatfirstincludesagreatdealofnursing,combinedwithmuchlickingand

BEHAVIORPATTERNS

cleaning.Ifdisturbedbyexperimentersorcaretakersshecomesoutofthenestboxandinvestigatesorbarksattheintruders.Shemakesnoattempttodefendthepuppiesagainsthandlingbyfamiliarpersons,butoftenseemsnervousanddiscontinueshercarewhiletheyareabout.Consequently,itisessentialtokeepthemotherandherlitterinundisturbedsurroundingsforthefirstfewweeks.

Individualdifferencesintheattentivenessofmotherstowardtheiroffspringarecommon,andwewishedtofindoutwhethertherewereconsistentdifferencesbetweenthedifferentbreedsinrespecttomaternalcarewhichmightaffectthebehavioroftheiroffspring.Wethereforecollectedobjectivedataonthemother-offspringrelationshipandselectedtheagesof1weekand7weeksforparticularstudy,theformerbecausematernalattentionwasclosetoitsheightatthispoint,andthelatterbecauseitisatimewhenallmothersareintheprocessofweaningtheirpuppiesandmightexhibitdifferentialbehaviorifiteveroccurred.

Nursingbehavior.—Whilewemadetheweeklyobservationsandweighings,wealsorecordedwhatthemotherwasdoingaseachpuppywastakenawayfromherandplacedonthescales.AsseeninFigure6.4,themotherscontinuedtonursetheirpuppiesverynearly

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SOCIALRELATIONSHIPS

171

100percentofthetimeimmediatelyafterbirth,butthisfiguresteadilywentdownwardinsubsequentweeks,beingapproximately30percentwhenthepupswere4weeksold.Therewasalmostnodifferencebetweencockerandbasenjimothers,buttheFimothersapparentlylefttheiroffspringinagreaternumberofcases.Thesehybridmothers(Fi)hadaverymuchbettermilksupplythanthepurebredonesandonthewholetookexcellentcareoftheiroffspring.Itlooksas

purebredonesandonthewholetookexcellentcareoftheiroffspring.Itlooksasiftheamountoftimespentnursingmightnotbedirectlydependentuponthemilksupplybutratherupontheresponsesofthepuppies.Thatisythestimuluswhichkeepsmotherwiththepuppiesmaybetheirsuckingbehavior.However,thenumbersofanimalsconcernedaretoosmalltodrawanydefiniteconclusionsexceptthatthedownwardcurvesobviouslyconfirmtheimpressionthatthemothersaremuchmoreattentivetothepuppiesintheearlypartoftheirlives.Asimilarconclusioncanbedrawnfromobservationsonundisturbedmothers(Table6.4),exceptthatundertheseconditionsthereareindicationsofbreeddifferencesbetweencockersandbasenjis.SimilarresultshavebeenobtainedbyRheingold(1963)withthisandnumerousothermeasuresofmaternalcare.

TABLE6.4

OccurrenceofMothersNursingPuppiesunder2WeeksofAgeduring10-mlnutedailyobservations

Retrievingtest.—Whenthepuppieswere1weekoldwetookthemotheroutoftheroomforafewminutes,tookthepuppiesfromthenestbox,anddistributedthematequalintervalsaroundtheedgesofthenurseryroom.Thenweputthemotherbackandobservedherfor15minutes,recordingwhichpuppieswerevisited,thenumberofvisitstoeach,andthetimewheneachpuppywascarriedbacktothenest.Themotherusuallywentfrompuppytopuppy,touchingeachonewithhernose.Thepuppiesmeanwhileusuallymadecontinuouswhiningnoises.Finally,themotherwouldpickeachoneupandtakeitbacktothenest,carefullycarryingitinherjawswiththepuppy'sfeetdanglingdown.

BEHAVIORPATTERNS

TABLE6.5

OccurrenceofRetrieving1-week-oldPuppiesbyPurebredandHybridMothers

Figuresbasedonverysmallsample.

AsTable6.5shows,thebasenjimotherscarriedtheiryoungbacktothenestmoreoftenthandidthecockers.However,therewerebigindividualdifferences,usuallyconsistentfromlittertolitter.Somemothersalmostalwaysretrievedtheirpuppiesandothermothersneverdidso.Tenofthe13cockermothersdidnoretrievingatall,whereas6outof8ofthebasenjimothersretrievedatleastsomeoftheirpuppies.Thisissomewhatcuriousbecausethecockerspaniel

someoftheirpuppies.Thisissomewhatcuriousbecausethecockerspanielbreedhasbeenselectedfortheabilitytolearntoretrieveandcarrygame.Apparentlythesetwotypesofretrievingarenotcloselyrelated,andwecanconcludethatthebasenjimothershavebeenselectedforbettermaternalcare,probablybecauseoflesshumanassistanceintheirnativeAfricanvillages.

Therewasconsiderablevariationintemperaturebetweendifferenttests,andonemightsupposethatthemotherswouldretrievethepuppiesmorepromptlyifthepuppieswerecoldandmakingmorenoise.Analysisofthedatashowedthatthetemperaturehadnoconsistenteffect,butratherthatthecharacteristicbehaviorofthemotherwastheimportantfactor.

Anotherinterestingobservationwasthatthemothersseemedtoplaynofavorites.Theyvisitedeachpuppyaboutthesamenumberoftimes,andwhentheybegantobringthembacktheydidsoinwhatappearedtobearandomorder.Sometimesthemotherwouldbringbacksomeofthepuppiesandliewiththeminthenestbox,leavingtheothersoutside.Atothertimesthemothermightstopandallowapuppytonurseoutsidethenest.Wedidnot,however,makethecriticaltestofrepeatingtheobservationtoseewhetherthepup-picswerecollectedinthesameorder.

Thesedataconfirmtheimpressionthatdogmothersmakelittleifanydistinctionbetweenmembersofthelitter.Tinsisquitedifferent

fromtheconditionsofhumanmotherhood,inwhichthenecessarilydifferentagesofchildrenmakedifferentialtreatmentnecessary.Thedogmotherisinthesamesituationasahumanmotheroftwins,orperhapsquintuplets,allbeingthesameageandverymuchalike.Theonlytimeadogmotherwillshowobviousdifferentialtreatmentisinthecaseofasickordvingpuppy.Oncethepuppybeginstogetcoldandinactive,themotherpaysverylittleattentiontoit.

Weaningtest.—Whenthepuppieswere7weeksofage,wetookthemotheroutofherpenforanhour,sothatmotherandpuppieswereseparatedforaconsiderableperiod.Wethenputherbackwiththepuppiesandrecordedtheensuingactivitiesonachecklist.Usuallythepuppieswouldallrushtowardthemother,attemptingtonurseasshemovedaroundtheroom.Theirbehaviorwasquitesimilartotheresponsegiventoahumanhandlerwhenheholdsoutahandtotheyoungpuppies.Ifthemotherallowedthemtonurse,sheusuallystoodstillforafewminuteswhiletheyleapedaround,pawed,andsucked.Whiletheyweredoingthisshemightvomit,whereupontheyatethenewfood.Iftheysubsequentlytriedtonurse,shewouldturnontheoffendingpuppieswithaloud

subsequentlytriedtonurse,shewouldturnontheoffendingpuppieswithaloudgrowl,openinghermouthasiftobiteandrushingtowardthem.Thepuppiesatonceretreated,sometimesrollingontheirbacksandyelping,butthemotherwasneverseentoactuallybiteoneofthem.Atthisagesuchbehaviorwastypicalofalmostallmothersandtheiroffspring.

Anothertestwastoplaceaboneinthepenwiththemotherandpuppies.Inalmosteverycasethemotherdidnotcompetewiththem,althoughshewasalwaysdominantoverthemwhentheyattemptedtonurse.Inothersituationswherethemotherandpuppieswerefeddishesofsemi-solidfood,wehaveobservedmotherswhichwouldtakepossession,drivethepuppiesaway,andburythefoodwithshavingsfromthefloor.Thenormalbehaviorofmotherstowardpuppiesofthisage,however,seemstobetolimitthepuppies'nursingbehaviorbuttoallowthemtoeatotherfoodatwillwithoutcompetition.

Followingtest.—Themothersweretakenawayfromthepuppiesat10weeksofage.Neitherappearedtobedisturbedbythechange.Themothershadonlyonecontactwiththepuppiesthereafter,at18weeksofage.Atthistimewebegantotrainthepuppiestowalkonaleash.Wesoonfoundthatifwebeganleashtrainingwithoutsomepreparation,thepuppiesbecamefrightenedanddidverypoorlyonthetest.Therefore,asanintroductiontotheleash,wefirsttrainedthepuppiestofollowwithoutit.

Onthefirstdayofthetestthepuppieswerefedaspecialdishoffishbytheexperimenter,andthesamethingwasrepeatedthenextday.Onthethirddaytheexperimenterwentintothepenwiththefooddishesbutinsteadofgivingthemtothepuppies,shewalkedoutofthepenandtowardthelaboratorythroughanexperimentalfield.Thepuppieswerefedaftertheyhadfollowedherintothelaboratory.Onthefourthdaythepuppiesweretestedoneatatime.Theexperimenterdidnotcarrythefoodbutsimplywalkedalong,andinsteadofgoingdirectlythroughthefield,shewentaroundtheedgeofthefence.Thus,ifthepuppywasinterestedonlyinthefoodreward,itcouldrunaheadoftheexperimenter.Theamountoftimewhichthepuppyspentwithinadog'slengthoftheexperimenterwasrecordedtogetherwiththetotaltimespentwalkingfrompentolaboratory.Theexperimenteralsoratedthepuppyaccordingtohowcloselyitfollowed,providingasecondmeasureofthetendencyofapuppytofollow.Onthefinaldayoftheexperimentthesameprocedurewasrepeated,exceptthattheexperimenterledthemotherofthepupsonaleash,allowingthepuppytofollowatwill.

Thisisnotaperfectexperimentfordeterminingwhetherthepuppyismore

Thisisnotaperfectexperimentfordeterminingwhetherthepuppyismoreattractedbythehumanhandleroritsmother.Itshouldhavebeendoneinreverseorderaswell,tocancelthepossibleeffectoftraining.Astheexperimentwasactuallyrun,almosteverypuppyspentmoretimeclosetothehandlerwhenthemotherwasalsopresent,andoftenthreetimesasmuch.Wecanatleastconcludethatthepuppieswerestillstronglyattractedbytheirmother(Fig.6.5).Ontheotherhand,thereactionofthemothertothepuppieswaseitheroneofindifferenceorrejection.Ifthemotherhappenedtobeinheat,aswassometimesthecase,shemightbeapproachedbyamalepuppybutwouldwarnhimoffwithagrowl.Whenevertinssortofbehavioroccurred,themotherwasstronglydominantoverthepup.

Inconclusion,themothersdevelopthreetypesofrelationshipswiththeiroffspring.Inthecare-dependencyrelationship,developmentproceedstowardadecreasingamountofmaternalcareandincreasingindependenceofthepuppies.Thischangeisbroughtaboutintwoways.Themotherbeginstoleavethepuppiesmoreoftenandatthetimeofweaningactivelyrejectsthem.Thereislittleornodifferentia]treatmentbythemother,whohasthesamegeneralrelationshipwithallthepuppiesinthelitter.Thephenomenonofsiblingrivalrysimplydoesnotoccurinordinarydogdevelopment.

Thereis,however,competitionoverfood,andthepuppies,whoneverseemtocompetewitheachotherformaternalcare,develop

SOCIALRELATIONSHIPS

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Fig.6.5.—Averagetimespentwithhandlerduringthe"followingtest."Notethatthesameorderismaintainedbetweenbreedsineverytest,withoneexception.Allbreedsspentmoretimewiththehandleronthesecondday,whenthemotherwasalsopresent.

strongdominancerelationshipswitheachotherinconnectionwithfood.Thedominancerelationshipbetweenmotherandpuppiesisquitedifferent.Themotherdoesnotordinarilyexertdominanceinthepresenceofabone,althoughsheisdefinitelydominantinothersituations,particularlywhenweanedpuppiesattempttonurse.Eventhistypeofdominanceisdifferentfromthatbetweenpuppies,asitneverseemstoinvolveactualfighting,butisdevelopedandenforcedsolelybymeansofthreats.

The"followingtest"indicatesthatundertheproperconditionsaleader-followerrelationshipcouldbedevelopedbetweenmotherandoffspring,anditispossiblethatthismayoccuroccasionallyinthewildCanidae.However,inmostcaseswolfpuppiesdonotstaywiththeirparentsbutformnewpacksoftheirown.Awell-developedleader-followerrelationshipisnotacharacteristicpartofeither

well-developedleader-followerrelationshipisnotacharacteristicpartofeitherdogorwolfsocieties.

THEDOG-HUMANRELATIONSHIP

Aswesawinthepreviouschapter,therelationshipsbetweendogsandhumanbeingsmaydevelopinmanydirections.Atoneextreme,

apuppyraisedentirelyapartfromhumanbeingsmaylaterreacttowardthemwithextremefearandhostility.Attheother,apuppytakenawayfromdogsatanearlyagetransfersallitssocialrelationshipstothehumanspeciesandbecomesan"almosthuman"dog.Whateverthisrelationshipmaybe,itisnormallywellformedby7weeksofage,althoughitgoesondevelopingandchanginglongafterthat.Weshallnowdiscussthefurtherdevelopmentofthedog-humanrelationshipandtheeffectofgeneticdifferencesuponit.

Anyrelationshipis,ofcourse,determinedbythebehaviorofbothparties.Sincewewereinterestedprimarilyinthebehaviorofthedogsandnotoftheirhumanhandlers,wetriedtostandardizethehumanhalfoftherelationship.Weinstructedallexperimentersandhandlerstotreatthepuppieswithuniformkindnessandnottomakespecialpets.Intestsituationswemadeitaruletogiveeverydoganequalopportunity,withoutplayingfavorites.Ifanyspecialtreatmenthadtobegiventooneanimalinalitter,theinstructionsweretodothesamethingtoallmembersofthegroup.Whiletesting,allexperimenterswereinstructedtowearwhitelaboratorycoatssothattheirgeneralappearancewassimilar,althoughtheydifferedindetailsofclothing.

Becauseofthegoodscientifictrainingandco-operationoftheexperimenters,theefforttostandardizehumanbehaviorwaslargelysuccessful.Fromtheviewpointofanalyzingtheeffectsofheredity,theresultswereexcellent.Anunexpectedresultwasthatthequalityofthesocialrelationshipwhichdevelopedwassomewhatshallow.

Thedevelopmentofthecare-dependencyrelationship.—Ourchiefexperimentalmeasureherewasthehandlingtest,describedinthepreviouschapter.Thisisessentiallyatestofsocialrelationships,anditsresultsaredividedintoseveralparts.Thefirstincludesinitialresponsesbythepuppytothreateningbehaviorbytheexperimenter,andthesearescoredasreactionsofescapeandavoidance.Second,asthepuppiesgrowoldertheybegintoreacttowardthehandlerinmuchthesamewayastheyacttowardthemother,runningtowardhimand

muchthesamewayastheyacttowardthemother,runningtowardhimandwaggingtheirtailsandlickinghishands.Stilllater,thepuppiesbegintoreactastheywouldtowardtheirownlittermates,withagreatdealofplayfulfightingandoccasionalplayfulsexualbehavior.Thepositivepatternsofbehaviortendtooccurincombinationwitheachotheratthisage,andtheirseparationisperhapssomewhatartificial.Inscoringthetest,however,wedividedtheresponsesintofearfulbehavior,playfulfighting,socialinvestigationandet-epimeleticbehavior,andattraction.Theet-epimeleticbehaviorandattractionscoresareperhapsmostcloselyrelatedtothecare-depend-

Thefivepurebreeds.Lefttoright,wire-hairedfoxterrier,Americancockerspaniel,Africanbasenji,Shetlandsheepdog,andbeagle.

**ipi

Outsiderunswherethepuppieslivedfrom16to52weeksofage.InthebackgroundisthenurserywinsoftheBehaviorLaboratory.

Nurseryroominterior.Shetlandsheepdogfemalecarriesapuppyinaretrievii..Puppieslivedinroomssuchasthisonefrombirthuntil16weeksofage.

BehaviorLaboratoryandStaff

BehaviorLaboratoryandStaff

Backrow:DanielReynolds,PearlMcFarland,DanielG.Freedman,DonaldDickerson,JohnA.King,DouglasG.Anger,DuaneBlume,EdnaDuBuis,FrankClark,SheldonIngalls,HoweSmith.

Middlerow:MaxineE.Schnitzer,MarianBurns,FlorenceSmith,MargaretCharlesHiggins.

Frontrow:ClarenceC.Little,JohnPaulScott.(JohnL.Fullerwasawayonleavewhenthispicturewastaken.)

Ancestralcockerspaniels04149and0415£

Someoffspringoftheancestralcockespanielsusedinthecross.

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Backcrosstothecockerspaniel,litter2249-57.Notecocker-likeearsandsegregation

oflongandshorthair.Theseandfollowingpicturesofhybridswerealltakenat16weeksofage.

Backcrosstothebasenji,litter3301-06.Noteuniformshorthair,theresultofadominantgene,andbasenji-likeappearanceofsomeanimals.

PilOTUI

CSBF2litter3394-3400.Noneofthe72puppiesinthetotalF2populationshowedanexactresemblancetoeitherparentbreed.

Pygmiesreturningfromahuntingtripwithabasenji.Thenetsareusedtotrapgamesuchasthesmallantelopescarriedbvthehunters.Thebasenjirunswiththemastheybeatthebrush,andthebellarounditsneckhelpstofrightenthegame(bypermissionoftheAmericanMuseumofNaturalHistory).

HuntingpartyatNinevah,Iraq,1952.TheirthreedogsbelongtothebreedfromwhichtheEuropean,greyhoundswereprobablydeihed,beingbroughtbackbyCrusaders(photobyR.T.Hatt).Thesalukiisabreedde-velopedfromthesamesourceinmoderntimes.

Left:MalepurebreddingoinAustralia(photobyDr.X.W.G.Mcintosh).Xotegeneralsimilaritytothebasenji.Right:Kurdishguarddog.Iraq,1952.Notestronglycurledtail.Animalssuchasthiswereusedinancienttimesaswardogs,aswellasforguardingflocksandproperty(photobyR.T.Hatt).

Forcedtraining

Above,apuppyistaughttoremainonthescaleswhileweighed,startingatbirth.Thepuppyinthepictureisonlytwoweeksofage.

Left,theleashcontroltest.Abalkatthestairs.

Basicrewardtraining

Goal-orientationtest.Uponreleasefromthestartbox,thepuppylearnstoruntothedishoffoodinitsownpen.

Advancedrewardtraining

Motor-skilltest.Inthis,themostdifficultpartofthetest,thedogmustclimbthe

Motor-skilltest.Inthis,themostdifficultpartofthetest,thedogmustclimbtheramptoadishoffoodontopofboxes5feethigh.

Detourtest(firstbarriertest).Inthisfirstproblem-solvingexperience,thepuppymustgoawayfromthegoalonthefarsideofthebarrierinordertoreachit.

Manipulationtest.Thepuppymustgetthedishoutofthebo:withhisDawsorteethinordertoeat.

Mazetest.Apuppyapproachestheexitthefoodreward.

T-Mazeanddelayed-responsetest.Onlydoorleadstoanexit.Inthedelayed-respitest,thepuppymustrememberaprevsignal.

Trailingtest.Puppylearnstofollowanartificialtrail.Asingledropoffishjuiceisplacedoneachmetalplate;thetrailendswithasmalldishoffish.

Spatial-orientationtest.Onlytherighthandrampleadstothegoal.Arrangementofthegoalboxandrampsisalteredineachpartofthetest.

encyrelationship.AsseeninFigures5.9and5.10,thesescoresrisequiterapidlyandthenleveloff.Byoneyearofagetheyhavedecreasedconsiderably,indicatingthattheanimalsarenowmoreindependent.

Anothermeasureofdependencyisthe"followingtest,"alreadydescribedin

Anothermeasureofdependencyisthe"followingtest,"alreadydescribedinconnectionwiththemother-offspringrelationship.Thetimespentclosetoahumanhandlervariedagreatdealamongindividualpuppies,butthereareaveragebreeddifferences.Cockers,forexample,spendmoretimeclosetothehandlerthandobasenjisontheaverage,althoughsomeoftheindividualdogsspendingthemosttimewiththehandlerwerebasenjis(Fig.6.5).

Formostofthedogs,beingremovedfromthepensandtestedwasarewardingexperience.Wheneverahandlerappearedatthegate,thepuppieswouldswarmtowardhim,attemptingtogetout.Inmostoftheteststheyobtainedbothafoodrewardandtheopportunitytomoveintoanewenvironment,andtheypresumablyassociatedtheexperimenterswiththeserewardingexperiences.Wemadecertainspecialexperimentsinanattempttoanalyzethisrelationshipinmoredetail.

Thefirstoftheseexperimentswasastudyoftheeffectoffeeding.Foodrewards,whichcanbeusedsoeffectivelytomotivatelearnedbehavior,mighthaveapowerfuleffectonsocialrelationshipsandtheattractionofananimaltowardthosewhofedit.Thefactsdonotbearthisout.Mostoftheregularfeedingwasdonebyanimalcaretakers.Thepuppieswereintenselyinterestedinthematfeedingtimebutlostallinterestassoonasfeedingwasoverandpaidlittleattentiontothemthereafter.And,aswesawinthelastchapter,puppieswhicharemachinefedbecomejustasattachedtopeopleasthosewhicharehandfed.Inshort,apuppywhichismerelyfedregularlybyhandandgivennootherattentiondevelopslittlemorerelationshipwiththefeederthanhewouldwithafeedingmachine.

Wecanconcludethatfeedingitselfisaminorpartofthecare-dependencyrelationship.Thisdoesnotmeanthatfoodcouldnotbecomeanimportantpart,particularlyiffoodwasmadeconditionaloncertainacts,andsometimesgivenandsometimeswithheld.Butitdoeslookasifthemereactoffeedingdoesnotproduceastrongemotionalreaction.Ineverydaylanguage,apuppydoesnotautomaticallyloveyoubecauseyoufeedit.

However,ElliotandKing(1960)didadifferentsortofexperimentinwhichtheyregularlyhandfedagroupofpuppiesbutmadenoothercontactwiththem.Halfthepuppieswereunderfedandhalfwereoverfed.Thepuppieswerefedtwiceadayafterbeing

weanedat4weeksofage,andsoonbecamestronglyinterestedinfoodastheirregularmealtimesapproached,runningtothegateandwhiningrepeatedly.At5

regularmealtimesapproached,runningtothegateandwhiningrepeatedly.At5weeksofage,theunderfedandoverfeddogsshowednodifferenceswhengiventhehandlingtest.At6and7weeksofage,however,theunderfedpuppiesshowedlessavoidanceandmoreattraction,thedifferencesbeingsignificantatthe.01level.Bothgroupsweremoreafraidofastrangehandlerthanofthepersonwhoregularlyfedthembutexhibitedthesamedifferencesinreactiontoeitherhandler.Astheygrewolderthesameaveragedifferencespersistedbutwerenolongerstatisticallysignificant.Wecaninterprettheseresultsasmeaningthatmakingthepuppieshungryspeedsuptheprocessofprimarysocialization(i.e.,theformationofasocialrelationshipwithhumanhandlers),althoughtheoverfedpuppiestendtoeventuallycatchupwiththeotherswithoutthespecialimpetusofhunger.

Allthepuppiesinthisexperimentexhibitedanotherinterestingaspectofbehavior,inthatneitherexperimentalsnorcontrolsdevelopedasocialrelationshipwithhandlersasrapidlyaspuppiesintheregular"schoolfordogs,"wheretheyweregivenmuchhumancontactinadditiontofeeding.Wemavconcludethathandfeedinghasadefiniteeffectonthedevelopmentofthesocialrelationshipbetweenpuppiesandpeople,particularlvifthepuppiesareunusuallyhungry,butthattherelationshipwillalsodevelopnormallywithoutfeedingbeinginvolved.Thisagreeswithourknowledgethatstrongrelationshipsdevelopbetweenlittermatesinspiteofthefactthatonelittermateneverfeedsanotherbutinsteadoftencompeteswithhimforfood.

Relationshipsofhome-reareddogs.—Morelightisthrownontheoriginofprimarysocialrelationshipsbvourexperimentwithhomereareddogs.Thiscouldbedoneononlvavervsmallnumberofanimals,sothatgeneralconclusionsareimpossible.Eachpuppywastakenfromthelitterat4weeksofageandraisedinthehomeofastaffmember.Eachhomewassomewhatdifferentfromtheothertwo.Silver,theShetlandsheepdog,Livedinahousewithtwosmallboysandatomcat.George,thebeagle,livedwithayoungmarriedcouplewhohadnochildrenbutdidhaveacat.Gyp,thebasenji,wenttoahomewheretherewasalreadyanadultfemaledogandseveralsmallchildren.Allthefamilieswerefondofpetsbutdifferedsomewhatintheirideasofdog-rearinganddiscipline.

Thepuppieslivedtheordinarylivesofhouseholdpets,exceptthattheywncfrequentlytakenbacktothelaboratoryandtested.Whilethere,theywerekeptapartfromotherdogsandmightspendall


daybythemselvesbeforetheywerereturnedtotheirhomes.Aswesawfromotherexperiments,isolationisanunpleasantexperienceforapuppy,andoverandoveragaintheyhadtheexperienceofbeingplacedinanunpleasantemotionalsituationandeventuallyrescuedfromit.Wewouldexpectthatthesepuppieswouldhavestrongemotionalreactionsassociatedwithhumanbeings.

Ingeneralthesepuppiesweremorefreeandconfidentwithhumanbeingsthanthekennel-reareddogs.Ontheteststheysometimesdidbetter,particularlywhenwiderexperiencemightbeofsomeassistance,buttheyalsodidworseinsometestswhichwerebasedonthekennelexperience.

Themoststrikingresultwasthedifferenceinadultbehavior.Twoofthepuppiesbecameextremelydependentandhighlyattachedtopeople.Oneoftheusualproblemsofraisingapetbeagleisitstendencytogooffhuntingforhoursatatime,neverreturningtothehouse.George,thebeagle,wouldscarcelyleavehisowners'yard.Silver,theShetlandsheepdog,wasinstantlyresponsivetohumanbehaviorandeasilytrained,eitherpositivelyornegatively.Hedefendedhisyardagainstallstrangedogs,bothmaleandfemale.Hebecamesexuallyresponsivetothecatwithwhichhewasbroughtup,whilethebeaglebecameattachedtotheclothbagofavacuumcleaner.Ontheotherhand,Gyp,thebasenji,becamemoreandmoreindependent,roamingthestreetsandfightingwithotherdogs.Perfectlybehavedinthelaboratory,hebecamealmostacaninedelinquentathomeandeventuallybecameuncontrollable.

Althoughtheenvironmentwasnotuniformforthesethreeanimals,thesamegeneraltreatmentproducedintwoofthedogsaconditionofoverdependencyandalackofmaturity,buthadrelativelylittleeffectontheother.Thebasenjibecame,asadog,anormallyindependentanimal;asapet,hewasoverlyindependentanddifficulttocontrol.Thebeagleandsheltiedevelopedamuchricheranddeeperrelationshipwithhumanbeingsthandidthekenneldogs,whereasthebasenjiwasmuchlessaffected,possiblybecauseofcontactwithanotherdoginthehomeaswellashisdifferentheredity.

Theeffectofhomerearingonthebehaviorofthesethreedogscanbedeterminedbycomparingtheirtestrecordswiththoseofothermembersofthesamebreedasdistributedonthestaninescales.Asmightbeexpected,themostobviouseffectwasontherelationshiptoahumanhandler.Thehome-reareddogswerealllessfearfulandshowedmoreplayfulaggressivebehaviorand

dogswerealllessfearfulandshowedmoreplayfulaggressivebehaviorandmoreevidenceofattractionduringthehandlingtests.Gyp,thebasenji,was

180BEHAVIORPATTERNS

anunusuallyconfidentdogat5weeksofage;andSilver,theShetlandsheepdog,showedanunusualamountofattractiontohumanhandlersat13to15weeksofage.Boththesescoresweremorethantwotimesthestandarddeviationawayfromtheaverageoftheirrespectivebreeds.

Similareffectsshowedupinthereactivitytests.Thepetsweremoreactive,stoodmoreerect,andshowedmoretendencytoinvestigatetheirsurroundings.Alltheseresultsareconsistentwiththeinterpretationofananimalwhichisconfidentinstrangesurroundings.Onepeculiaritywasthatallofthemshowedmoremusculartremorthantheaverageinreactiontorestraintinastrangeplace.Ontheperformancetests,alltheanimalsdidbetteronthefirstbarriertestgivenat3weeksofage,whereconfidenceinastrangesituationundoubtedlyhasastrongeffectontheoutcome.Inover-allperformance,thebasenjiscoredbetterthanaverageonfiveperformancetests,poorerthanaverageinone,andaverageinfourmore.Hedidoutstandinglybetterthanotherbasenjisinthetrailingtest.

Thebeaglewasbetterinthreetests,worseintwo,andaverageinfive,confirmingtheimpressionofhisownersthathewasadogofquiteaverageintelligence.Hedidoutstandinglywellontheleash-controltest,butthisprobablyreflectsprevioushometraining.

TheShetlandsheepdogdidbetteronfourtests,poorerinone,andaverageinfive,turninginoutstandingperformancesonthefirstbarriertestandonthetrailingtest.Thebehaviorofalldogsonthelasttwotestswereapparentlygreatlyaffectedbytheirreactionstostrangesituations.Thesheepdogshowedaslowerthanaverageperformanceonspeedscoresintwoofthetests,reflectingthefactthatthisanimalbecameobeseasitgrewolderandcouldnotrunasfastastheothers.

Thehomeenvironmentchieflyaffectedtherelationshipofthedogswithpeopleandtheirconfidenceinstrangesituations,andthisenabledthemtodobetterthantheaverageincertaintestsinwhichthiswasimportant.Theiradditionaloutsidetrainingandexperiencewithricherenvironmentsbenefitedtheminsomeothertestsbutdidnotmaketheminto"superdogs."

CONCLUSIONS

CONCLUSIONS

The1mostimportantconclusionthatranbedrawnfromtheseexperimentsisthathereditydoeshaveanimportanteffectuponthedevelopmentofsocialrelationships.Involving,asitdoes,aprocess

ofmutualadaptationandlearning,theexpressionofheredityinasocialrelationshipisfarremovedfromtheprimarybiochemicalactionofagene.Nevertheless,theendresultcanbeexpressedinasimplestatementthatthedifferentiationofbehaviorinasocialrelationshipisproportionaltothedifferencesinthecapacitiesofthetwoindividualsinvolved.Inthecaseofthedominance-subordinationrelationshipdevelopedbetweenyoungpuppies,theoutcomeisaffectedbybothsexandbreeddifferencesinthecapacitytodevelopaggressivebehavior.Theseexperimentshavemanyotherimplications,andtheywillbediscussedingreaterdetailinthefinalchapter.

Whilewewereabletoworkwithonlyalimitednumberofmothers,therewereobviousindividualdifferencesintheirbehaviortowardtheiroffspring.Verypossiblyalargersamplewouldshowthattherewereimportantbreeddifferencesinmaternalbehavior.Oneinterestingfactwasthatthehybridmothers,whichgavemoremilkthanpurebredones,spentlesstimenursingtheiroffspring,suggestingthatthemotherstendedtoallowtheiroffspringtonurseaslongasthepuppieskeptsucking.Thereisagreatdeclineintheamountoftimespentinnursingduringtheneonatalperiod;sothatbythetimethepuppiesentertheperiodofsocialization,nursingisaquickandcasualaffair.

Aswellasdifferencesinmaternalcare,therearebreeddifferencesinthereactionsoftheoffspring.Thissuggeststhepossibilitythatpartofthebehaviorwhichweconsidercharacteristicofabreedmaybeareflectionofthesocialenvironment,i.e.,thebehaviorofmothersandlittermates.Inthecaseofsocialbehavior,geneticfactorsmayinpartcreatetheirownenvironmentwhichinturnmodifiestheirdevelopmentandexpression.

Incontrasttothedog-dogrelationships,whichwereallowedtodevelopfreely,thedevelopmentofdog-humanrelationshipswasmorestrictlycontrolled.Asfaraspossible,thehumanhandlerstreatedeachpuppyinthesameway.Theycontrolledandstimulatedthebehaviorofthedogsbutrespondedtotheminonlyalimitedway,sothatthepuppiescouldcontrolhumanbehaviortoonlyaverysmallextent.Theresultwasarelativelyshallowsocialrelationshipcomparedtothedeeperandmorecomplicatedrelationshipwhichhousedogsordinarilydevelopwiththeirmasters.

developwiththeirmasters.

Wewereabletocomparetheeffectsofnormalhomerearinginthecaseofthreedogs.Theprincipaleffectwastomakethemmoreconfidentinthepresenceofpeople,andthisinturnaffectedtheirperformancewhereconfidencewasneeded.Basenjishaveatendencytobeafraidofstrangeobjectsandapparatus,andthemore

confidenthome-rearedbasenjididmuchbetterinthetrailingtest,inwhichsuchfearswerearealhandicaptoperformance.Otherwise,homerearingseemedtohelptheanimalsintestswherewiderexperiencewasofvalueandtohandicapthemwherekennelexperiencewasimportant.Wealsohadtheimpressionthatthethreehome-reareddogshadmorehighlydifferentiatedbehaviorasindividualsthandidthoserearedinakennel.Thisundoubtedlyresultedinpartfromdifferentialamountsoftrainingbutalsosuggeststhepossibilitythatpartofwhatweconsiderthecharacteristicbehaviorofdogbreedsisdevelopedandexaggeratedbydifferentialtreatment.

Thuswereachthegeneralconclusionthatthecourseofdevelopmentofsocialrelationshipsisdeterminedbygeneticdifferencesbetweentheindividualsinvolvedandbythenatureofthesocialenvironment.Socialrelationshipsinturninfluencealmostallotherbehaviorandaretheframeworkwithinwhichalltestsofperformancetakeplace.

Precedingchaptershavedealtwithbasicinformation:theoriginofdogs,theirbasicpatternsofbehavior,andthebroadoutlinesofbehavioraldevelopment.Thenextsectionwillemphasizethedevelopmentandanalysisofbreeddifferencesinperformance,includingthecapacitytoaccepttrainingandtosolveproblems,andthedependenceofeachoftheseuponbasicphysiological,emotional,andanatomicalcharacteristics.

THEDEVELOPMENT

ANDEXPRESSION

OFBREEDDIFFERENCES

ANALYSISOFGENETICDIFFERENCES

Beforepresentingtheresultsofthegeneticstudiesitisnecessarytoexplainscoringsystemsandmethodsofstatisticalanalysis.Forthemostpart,ourprocedureswereconventional,butsomeexplanationofthegeneticsignificanceofourresultsisnecessaryforpersonsmorefamiliarwithbehaviorthanwithbiometricalgenetics.Itwillbecomeclearthat,althoughstatisticalanalysisisessentialforaninterpretationofourfindings,itisnotsufficientinitself.Toagreatextent,theinternalconsistencyofthedatamustbeconsideredinarrivingatconclusions.Inanexperimentinvolvingsomanyvariables,numerousbreeddifferencesthataresignificantattheconventional5percentlevelwouldbeexpectedbychance.The1percentlevelofsignificanceisprobablyasaferboundaryinmultivariatecomparisons.

Furthermore,quantitativeestimatesoftheheritabilityofatraitdependuponclearseparationofgeneticandenvironmentalsourcesofvariance.Purebreedsofdogsareappreciablyheterogeneousinmanyrespects;hence,thewithin-breedcomponentofvarianceisareflectionofgeneticaswellasenvironmentaldifferencesamongmembersofthesamebreed.Frequentlythevariancebetweenbreedswasconsiderablygreaterthanthatwithinbreeds;andonoccasionweusedthebetween-breedvariancecomponentasanestimateofgeneticeffects.Heterogeneityinthebreedscausesthebetween-breedvariancetogiveunderestimatesofthetotaleffectofheredity.

Theuseofbetween-breedvarianceasameasureofgeneticeffectsassumestheessentialsimilarityoftheenvironmentsofthedifferentbreeds.Inpracticethereweresystematicdifferences.Forexample,basenjipupsdevelopedinabasenjiuterus,andfor70daysafterbirthwerenursedandcaredforbyabasenjimother.Fortheirentire

185

186BREEDDIFFERENCES

periodofobservationtheylivedwiththeirbasenjilittermates,notwithcockerspanielsorbeagles.Bycross-fostering,byrearinginmixed-breedgroups,orbyrearinginisolation,itwouldhavebeenpossibletoisolatetheeffectsofdifferentialsocialenvironmentatvariousstagesoflife.Pilotstudiesofeachtypewere,infact,carriedout,butnotonascalelargeenoughtopermitdetailedstatisticalanalysis.Theoutcomesofallsuchexperimentswereconsistent;breedcharacteristicspersistedincross-fosteredpups,inisolation-rearedpups,andinpupstransferredaftersomeweeksormonthstoalitterofadifferentbreed.Becauseoftheseconsistentresults,webelievethatgeneticcontributionstobreeddifferencesovershadowenvironmentalcontributions.

Geneticheterogeneitywithinparentstockswouldtendtolowerestimatesofheritability,whilesystematicenvironmentaleffectswouldraisethem.Becausethetwopotentialsourcesoferrorworkinoppositedirections,wemayhopethataroughbalancewasattained.Beforeproceedingwithamoredetaileddiscussionofourmethodsofanalysis,wewilldescribethestaninesystemofscalingquantitativescores(Guilford,1950).

STANINESCORINGSYSTEM

Thescoresofoursubjectswereexpressedindiverseunitssuchaserrors,runningtimesinseconds,orarbitrarynumericalratingsderivedfromadescriptivescale.Thesescoreshavemeaningonlyinsofarastheyarerelatedtoaparticulartestingprocedure.Inordertomakedifferentsetsofscorescomparable,wehaveconvertedmanyofthetestresultstostanines.Inthissystemallscoresaredividedintoninegroupsbaseduponrankorderingandeachgroupofscoresisrepresentedbyasingledigit.Theconversionischosensothatthemeanofthescoresforthereferencepopulationiscloseto5.0andthestandarddeviationisabout2.0.Thusascoreof5.0indicatesthatthesubjectwasbetweenlimitsof±0.25standarddeviationsfromthemeanofthetransformed

betweenlimitsof±0.25standarddeviationsfromthemeanofthetransformedscores.Themeanofthetransformedscores,ofcourse,correspondstothemedianoftheoriginalscores.

Transformationofscoreshasanumberofadvantages.Intervalsonthestaninescaleare,inasense,uniformthroughouttherangeofscoreswithinaparticularpopulation.ThissatementisnottrueFormanyoitheoriginalscores.Forexample,inonetestinvolvingrunning-timesubjectsrunningatfullspeedcouldcoverthecourse

ANALYSISOFGENETICDIFFERENCES187

in2seconds.Ananimalaveraging4secondswasclearlyrunningmuchbelowmaximumspeed,andthedifferencebetween2-secondand4-secondsubjectswassignificant.Somedogsremainedwithintheapparatuslongafterthegatehadbeenopened,andtheirrecordedrunningtimesaveraged20secondsormore.Undertheseconditions,thedifferencebetween20and22secondswasnotcomparabletothatbetween2and4seconds.Conversionstoreciprocalsortologarithmsmighthavebeensatisfactory,butweselectedatransformationbasedonrankorderingasmoregenerallyapplicabletoalltypesofscores.

Thestanineconversionmakesitpossibletocompareperformancesinquitedifferenttests.Astaninescoreof7,forexample,alwaysmeansthatthesubjectwasbetween0.75and1.25standarddeviationsabovethemeanonthetransformedscale.Theoriginalscoresmayhavebeenrunningtimesorratingsofemotionality,butsuchdifferencesdonotaltertheprocedureofrankingwhichisthebasisofthetransformation.Staninesarealsoadvantageousforcomputations,particularlywhendeskcalculatorsmustbeemployed.Avarietyofanalysescanbeconductedmoreeasilyonscoresexpressedassingledigits.

Therearealsocertaindrawbacks.Thedisadvantageoftransformingdatainthiswayisthatitmayobscureordistortinformationwhichisobviousontheoriginalscale,orwhichcouldbebroughtoutmoreplainlybyusinganothertransformation.AsMather(1949)haspointedout,thereisnoapriorireasonforassumingthatonescalewillappropriatelymeasuretheeffectsofeverygene.Consequentlythestaninescalemayincertaincasesobscureprecisemeasurementsofbehavioraldifferencesandindicationsofgeneticsegregation.Theadvantagesofthemethod,however,outweighitsdrawbacks,particularlyifmanycomputationsmustbemade.

Theuseofstaninescarriestheimplicationthatthetraitsmeasuredbyourscoresareessentiallycontinuousratherthandiscontinuous,andthatthebasesampleusedtocomputethetransformationtableswasarepresentativesampleofthepopulationinwhichwewereinterested.Specifically,thismeansthatweassumethatdogsarenotdividedintobrightanddulloremotionalandnon-emotionalclasses,butthatintelligenceandemotionalityasmeasuredbyourtestsarequantitativecharacterswiththemajorityofthepopulationintermediateandrelativelyfewsubjectsattheextremes.Further,wehaveassumedthatthefivebreedschosenforstudyrepresentafaircross-sectionofdogs.Althoughtheseassumptionswerenotstrictly

BREEDDIFFERENCES

proved,thedistributionsofthetestscoresareingeneralagreementwiththem.Stanineconversionswerenotmadeonscoreswhosedistributionsobviouslycontradictedtheseassumptions.

Theprocedurefortransformingoriginalscoresintostaninesisillustratedbydatafromthemotivationtest.TheoriginalscorewasthetotaltimeinsecondsadogrequiredtoruntentrialsinonedaythroughanL-shapedcourse.Eachdogwastestedonthreeseparatedays,sothatthreescoreswereavailableforeverydog.Wechoseasampleof100dogs,10malesand10femalesfromeachofthefivepurebreeds,selectingatrandomwithineachbreedandsex.Thedistributionofthe300scoresisshowninFigure7.1.Thecurveis

RUNNINGTIME-MOTIVATION

MEDIAN

■—-*■-

300

400

500

SECONDS

Fig.7.1.—Distributionof296runningtimes(4scoresoffscaletoright)from100dogsgiven3trialseach.Thesamplingprocedureisdescribedinthetext.

markedlyskewed,butthereisnoevidenceofbimodalitywhichwouldjustifytheclassificationofsubjectsintofast-runningandslow-runningdogs.

Theoriginalscoreswerearrangedinrankorderandcut-offpointswereselectedatpointscorrespondingtocumulativepercentagesforsegmentsofanormaldistribution,one-halfastandarddeviationwide(Table7.1).Notethatthecumulationofscoreswasstartedfromtheslow-runningend,becausewewishedtoexpressourresultsintermsofspeedandthefastestsubjectshavethelowesttimescores.ThetransformationtostaninesshiftsthedistributionofscorestoanapproximatelynormalformasinFigure7.2.Wecan,there-

ANALYSISOFGENETICDIFFERENCES

TABLE7.1ConversionTable—OriginalScoretoStanine

fore,bytheuseofstanines,essentiallychangethebasisofmeasurementofanindividual'sbehaviorfromascalebasedonabsolutephysicalunitstoonebasedonperformanceofastandardpopulation.

60r

SPEE0MOTIVATION

3456789

STANINE

Fig.7.2.—Distributionof300motivation-speedscoresafterconversiontostanines.

ANALYSISOFVARIANCE

Analysisofvarianceseparatestheeffectsoftwoormorefactorsuponasetofmeasurements.Inourexperiments,themajorinterestlayinestimationofthecontributionofhereditytototalvariance.Totalvarianceisreadilyestimatedbystandardprocedures,andtodetermineheritabilityitisonlynecessarytofindsomemeansofcalcu-

190BREEDDIFFERENCES

latingthegeneticcomponent.Inpractice,thisissomewhatcomplex.Weshalldescribethesituationintheexperimentcomparingfivepurebreeds.

Inthisexperiment,potentiallygeneticcontributionscanappearinthreeforms:

1.Asystematiceffectbetweenbreedsmayappearbecauseofdifferencesingenefrequencybetweentheseveralbreeds.Weshalllabelthisvariance<t2hb.

2.Somegeneticvariationmaybeattributabletodifferencesingenotypesbetweenthevariousmatedpairsineachbreed.Weshalllabelthisvarianceo2hm.

3.Someofthevariationamongmembersofthesamesibshipisattributabletorandomsegregationintheoffspringofheterozygousparents.Wecallthis

randomsegregationintheoffspringofheterozygousparents.Wecallthisvariancecr2h.

Thedesignoftheexperimentdoesnotpermitseparationofcr2hfromenvironmentalvariance,butct2hbando2hmcanbeestimated,providedcertainassumptionsaremadewithrespecttoenvironmentaleffects.

Wecanalsosubdivideenvironmentallyproducedvariance.

1.Asystematicenvironmentaleffectcouldhavebeenproducedbytheassociationofpuppiesalmostexclusivelywiththeirownbreed.Thisvarianceweshalldescribeasct2eb.

2.Asimilarsystematicenvironmentaleffectcouldhavebeenassociatedwithaparticularmotherandwouldcharacterizeallmatingsofthismother.Thisvarianceweshallcallo2em.

3.Eachlitterhadaparticularanduniquelifehistorycharacterizedbyseasonofbirth,exposuretoaccidentalstimuli,testingbyaparticularresearchworker,etc.Thevarianceattributabletothesecommonlittereffectswewillcallct2el.

4.Eachsubjecthadcertainuniqueexperiences.Eventhoughweendeavoredtotreatallalike,absoluteuniformitywasnotpossible,andlittermateswerenot,ofcourse,boundbyanyexperimentaldesignintheirtreatmentofotherindividualsinthelitter.Variancedependentupontheseindividualexperientialdifferenceswedenoteaso2e.

Thecomplexityofsourcesofvariationissomewhatdiscouragingatfirst.Inalargeexperiment,itwouldtheoreticallybepossibletoisolateeachcomponent,althoughbiologicallimitationsonthenumberoflitterswhichasinglefemalecouldproducewouldinterferewitheventhebestpossibledesign.Ourexperimentwastoosmalltopermitdirectestimatesofallcomponents.Hence,wewereForcedtolooklordefensiblesimplifications.

Inthefirstplace,cross-fosteringfailedtodemonstratemajoreffects,andindividualsrearedinmixedlittersdidnotdiffermarkedlyfromtheirownbreed.Weconcludedthatindogs,<t2ebandct2emweretoosmallformeasurementinsmallsamples;hencetheywereneglectedinmostanalyses.Ineffect,suchansimplificationassumesthatculturaldifferencesbetweenbreedsarenotimportantdeterminantsofbehavioralvariation,althoughwelaterfoundevidencethat"breedenvironment"hasaneffectonsomeofthevariables(seechap.14).

"breedenvironment"hasaneffectonsomeofthevariables(seechap.14).

Theimportanceofct2elcanbetestedbydeterminingwhetherlittersofthesamematingdiffersignificantlyfromeachother.Whenthequestionisputtothedatatheanswerisnotstraightforward;theydoonsometestsbutnotonothers.Weconcludethatthecontrolofenvironmentfromlittertolitterwasimperfectinspiteofourbestefforts,andthatinanalysisweshouldtakeintoaccountbe-tween-littervariation.

Theseparationbetweencr2handcr>,bothcontributingtowithin-littervariance,isnotpossiblewiththedatafromthepurebreeds.Anestimateofthedistributionofthewithin-littervariancewas,however,possibleinthehybridizationexperiment.WecanbecertainherethattheF2andbackcrosshybridsweregeneticallymorediversethantheFi's,yetthewithin-littervariancesofbehavioralmeasureswerenotuniformlysmallerintheFi's.ThegeneticdiversityofthepurebredlitterswascertainlylessthanintheF2hybrids,andthegeneticcontributiontothevariancewithinsuchlittersmusthavebeenless.Thus,whenweassumethatthewithin-littervarianceofthepurebreedsisenvironmental,wemayunderestimatetotalgeneticeffectsforcharactersofhighheritability,buttheerrorisprobablytoosmalltobedetectableexceptinverylarge-scalestudies.

Finallywemustconsiderct2hbandAi,althoughourprimaryinterestisinct2hr.Byderivingourpurebredstocksfromafewcloselyrelatedindividuals,weendeavoredtoreducect2hmtoalowvalue.Wecanomitseparatecalculationofbetween-matingvarianceandincludeitwithbetween-littervariance.Insodoing,somegeneticcomponentswillbeincorrectlyclassedasenvironmental,andtheeffectwillbetoreducetheprobabilityoffindingsignificantbreeddifferencesandsoleadtoaconservativeestimate.Inanticipationweshallnotethatthisanalysisprovedsuitableforthebreedcomparisons.Amongthehybrids(seechaps.12and14)ratherlargedifferenceswerefoundamongmatingsofthesametype.

Insummary,asurveyofthesourcesofvariationinourexperi-

BREEDDIFFERENCES

mentleadstothefollowingsimplifiedschemaofanalysisforasampleofbbreeds,eachmadeupof/littersofkindividuals(Table7.2).

TABLE7.2

TABLE7.2

SimplifiedInterpretationofAnalysisofVarianceinBreedComparisonExperiment

Practicalcomputationsmusttakeintoaccountinequalitiesinthevarioussubgroups.

Inthisschema,threehierarchialmeansquaresarecomputedbetweenbreeds,litters,andindividuals.Thevariancebetweenindividualsofthesamelitterisameasureoftheeffectofnon-controlledenvironmentalandgeneticfactors.Themeansquareforlittersalsoincludesacomponentwhichweinterpretaspredominantlytheeffectofspecific-litterlifehistories.Anygeneticdifferencesinmatingsofthesamebreedwillalsobeincluded.Ifbetween-littereffectsarenon-significant,thenthewithin-littermeansquare(estimateof<r2h+o2e)isthepropertermfortheFtestofbreeddifferences.

Ifthebetween-littereffectissignificant,thentheproperdenominatorfortheFtestofbreedeffectsisthemeansquareforlitters(estimateof<r2e+o2h+kcr2EL).Obviously,thistestismorerigorousthanasimplecomparisonofbreeddifferenceswhichneglectspecific-littereffects,anditismoredifficulttoestablishsignificance.Becausetheprocedureisconservative,morefaithcanbeplacedonit.

Theratioofothbtototalvariance(o2h+or2e+o*bl+<r2ns)isknownastheintraclasscorrelationcoefficientandisperhapsthemostgenerallyusefulindexofthemagnitudeoftheeffectsofheredity.Acorrelationof.25,forexample,meansthatone-fourthofthetotalvarianceofapopulationdrawnatrandomfromthetotalsamplewouldbecluetobreeddifferences.Anotherintraclasscorrelationcanbecomputedforthelittereffect{ctel/cTc+cr'2h-fo2el)whichistheproportionofvariancewithinabreedattributabletospecific-litterhistories.Bothmeasureshaveprovedusefulinouranalyses.

Themostgenera]applicationsofthisbasictheoryarepresentedinchapter14inconnectionwithanover-allanalysisofvariationin

ANALYSISOFGENETICDIFFERENCES193

thepurebreedsandhybrids.Chapters8to10areconcernedwiththeanalysisofbreeddifferencesandtherelativeranksofthepurebreedsinvariouscapacities,whereaschapters11,12,and13areconcernedwiththeanalysisoftheresults

whereaschapters11,12,and13areconcernedwiththeanalysisoftheresultswithhybrids.

Moredetailedstatisticaltechniquesaredescribedandtheirapplicationdiscussedinseveralofthesechapters.Theanalysisofvariancemethodcanbeextendedtoincludedetailedanalysisofenvironmentaleffects.Elliotcarriedoutanelaborateanalysisofthissortuponthesecondbarrier(ormaze)test,whichisdescribedinchapter10.

Inchapter11,methodsaredescribedforestimatingthenumbersofgeneticfactorsinvolvedinaparticulartrait.Chapter12includesmethodsforusingoffspring-parentregressionsandfortheanalysisofhalf-sibandfull-sibfamilies.Thedesignofourcrossbreedingexperimentwassuchthatthesamepurebredfemalewasbredtotwodifferentmales,oneoftheotherpurebreed,andonebeingherownson.Thissamesonwasbredtotwogeneticallydifferentfemales,themotherandafullsister.Thismakesitpossibletocompareanimalshavingoneparentincommonandthustoestimatetheeffectsoftheparents.Thismethod,incontrasttothemoregeneralonedescribedabove,makesitpossibletoanalyzetheeffectsofhereditywithoutassuminghomogeneityoftheparentbreeds.

Finally,thewell-knowntechniqueoffactoranalysiswasappliedtotheresultsonthreedifferentoccasions,andthefindingsaredescribedinchapters13and14.Theassumptionsandlimitationsdiscussedaboveapplytoallproceduresemployed.Despitethecomplexityofthefactorsaffectingbehaviorandtheelaboratenatureofthestatisticaltechniquesrequiredfortheiranalysis,onebasicresultclearlyemerged:largeeffectsattributabletoheredityweredemonstratedinalmosteverytestweadministered.

CHAPTER8

EMOTIONALREACTIVITY

TheworkofHall(1941),Searle(1949),andothersonthegeneticsofratbehaviorindicatednotonlythatemotionalbehaviorwasaffectedbyheredity,butthatemotionalityhadanimportanteffectonperformancetests.Inourdogswethereforestudiedtheearlydevelopmentofsuchemotionalreactionsasdistressvocalizationandtailwagging,andparticularlythechangesinemotionalreactionsinresponsetohumanbeingsduringtheprocessofsocialization.Importantbreeddifferenceswerefoundinallthesecharacteristics.

Inadditiontotheirovertexpression,emotionsalsoincludeinternalresponseswhichcanbemeasuredbywell-knownphysiologicaltechniques.Thesetechniquesaremosteasilyappliedtolargeranimalsunderrestraint,andwethereforeplannedamajortestoftheemotionalandphysiologicalreactionsofolderpuppiesandgrowndogsastheystoodonaPavlovstand.Wehopedtodefinetheeffectofheredityuponexternalandinternalemotionalreactivity.

Reactivityisabroadtermwhichmayhaveseveralmeanings.Wedefinedreactivityastheintensityofallresponses,externalandinternal,madetoastimuluschange.Suchabroaddefinitioncreatessomeproblemsofmeasurement,sincethevariouspossibleresponsesdonotnecessarilyvarytogether.Nevertheless,theconceptseemstohavevalidityfromthepointofviewofgenetics.

DEVELOPMENTOFAREACTIVITYTEST

Apparatus.—Inordertoreducethereactivitymeasurementstomanageableproportionsandtofacilitatephysiologicalmeasure-

ments,subjectswererestraineduponaPavlovstand.Heretheywereexposedtoastandardsetofsituationsdesignedtoelicitanemotionalresponse.Sincewewereinterestedinobservingphysiologicalcorrelatesofreactivitv,weconnectedoursubjectstoanoscillograph,usingmodifiedbatteryclipsassurfaceelectrodes.Topreventthemfrompullingtheclipsoffortanglingthewires,dogswerelightlvrestrainedbylegloopswhichweretiedovertheirbacksandconnectedtoasteelbarabout4.5feetabovethefloor.Thesupportingframeforthisbarwasbuiltintoalargecage8X8X7feetwhichwascoveredwithscreenwireforelectricalshielding.Observersandrecordingequipmentwerestationedjustoutsidethecageinthesameroom.

Behaviorinthetestsituation.—Withinthiscageweobservedtheresponsesofthepurebredandhybriddogstoaseriesofsocialandnon-socialepisodes.Theresponseswereobviouslymodifiedbytheconditionsoftesting,andreactivitymeasuredinanothersituationmighthavetakenverydifferentforms.Themajorityofsubjectstoleratedtheattachmentofelectrodesandthefittingoflegloopswithanominaldisplayofexcitement.Goodvisualobservationsandoscillographrecordscouldbeobtainedfromsuchanimals.Afewsubjectsreactedsoviolentlytosimplerestrictionofmovementthattestinghadtobediscontinuedorcarriedoutinamodifiedform.Evenmorecommonweredogswhichslumpeddownintheharnessandweresoinhibitedthroughoutthatlittle

whichslumpeddownintheharnessandweresoinhibitedthroughoutthatlittledifferentiationofreactivitywasdetectablefromepisodetoepisode.ThesetwotypescorrespondedtoPavlov's(1928-41)"excitable"and"inhibited"animals,whichhetestedundersimilarconditions.Betweenthesetwoclasses,therewasanenormousrangeofvariability.Theextremepatternsappearedtobemoreareactiontothetestsituationasawholethantoitsspecificcomponents.

Ageoftesting;observervariation.—Asastandardprocedureeachsubjectwastestedatthreeages:17,34,and51weeks.Atthetimeofthefirsttestthedogshadjustbeenplacedinanoutsideyard;at34weekstheyhadcompletedthemajorbehavioraltestswiththeexceptionofspatialorientation.The51-weektestcameafterapproximately12weeksoflivingintheoutsideyardswithaminimumofhumanhandling.Inthesethreeteststheeffectsofchangesinage,previoustestexperience,andcurrentconditionsofmaintenanceandhandlingarecombined.Itwouldhavebeenpossibletodesignanexperimenttoseparatetheseeffects,butthiswouldhaveinvolvedmoresubjectsthanwereavailableandwouldnotneces-

196BREEDDIFFERENCES

sarilyhavegivenmoreinformationregardingbreeddifferences,sinceallbreedsweretreatedalike.

Overthecourseoftheexperimentchangesinpersonneloccurred,thusintroducingproblemsofvariationbetweentheratingsofindividualobservers.Toreducethissourceoferror,eachnewobserverwastrainedbvtheprincipalinvestigatoruntilratingswerejudgedtobereasonablvuniform.Asampleofcorrelationsbetweenobserverratingsonthesamesubjectvariedbetween.85and.95.

Episodesinthereactivitytest.—Thereactivitytestwasdividedintotenepisodes:(1)Preparation.Duringthisperiodofvariabledurationtheexperimenterattachedelectrodesandadjustedtherestrainingloops.(2)ControlI.Thesubjectwasleftaloneforoneminuteinanelectricallyshieldedcubicle,lightedfromtheinside.Anobserverviewedthesubjectfromthesidethroughascreenwhichblurredbutdidnotobscurethedog'sviewtotheoutside.(3)Quieting.Anexperimenterentered,spokesoftlytothesubjectwhileextendinghishand,walkedtotherearofthecubicle,andleftquietlyafter30seconds.(4)ControlII.ArepetitionofControlI.(5)Bell.Adoorbellattachedtothecubiclewallwassoundedfor30seconds,followedby(6)ControlIII.AnotherrepetitionofControlI.(7)Shock.Foursingleshocksfromaninductioncoilweredelivered

ofControlI.(7)Shock.Foursingleshocksfromaninductioncoilweredeliveredtothedog'sleftforelegat5-secondintervalsandobserva-tionswerecontinuedfor60secondsfollowingthefirstshock.(8)Threatening.Anexperimenterenteredthecubicle,graspedthedog'smuzzlewhilespeakinginaloudharshvoice,andforcedthesubject'sheadfromsidetoside.Inaddition,itwasoftennecessarvtountangleloopsorre-attachelectrodeswhichweredislodgedduringtheshockperiod.Allsuchhandlingwasdoneinabrusquemanner.(9)ControlIV.RepetitionofControlI.(10)Release.Afterreleasingthedogfromthelegloops,theexperimenterremainedstandinginthecubiclefor30seconds,thensteppedoutsideandwaitedbvthedoorforanadditional0.5minute.Latencyofthedog'sleavingthecubiclewasrecordedtothenearestsecond.

Ratingscales.—Ratingsofbehaviorweremadeineachofthe10episodeswithastandardchecklist.Eachspecificbehaviorpatternwasratedona5-pointscale,thehighervaluescorresponding

greaterenergyexpenditure.Exceptionsweremadeforsuchcate-

goriesasaggression(biting)whichwasscorednolowerthan4or

sionappearedonlywhensubjectsweremoreactive

thanav<Someitochaspostureandtailcarriage,were

ratedineachepisode;others,suchastailwaggingorvocalization,

EMOTIONALREACTIVITY

197

onlvinthoseepisodesinwhichsucharesponsewasobserved.Withthisratingsystem,thetotalscoreisameasureoftheaveragevigorofallformsofresponseover10episodes.DetailsofscoringareavailableinScottandFuller(1950).

Inaddition,graphicrecordsofrespiration,electrocardiogram,andelectromvogram(recordedfromthethigh)wereavailableforallexceptthepreparationandreleaseepisodes.Therespiratoryratedatahavenotvetbeenanalyzedcompletely.Heartratechangesfromepisodetoepisodewerenoted,aswellastheheartratesundercontrolconditionsandanindexofsinusarrhythmia.Anarrhythmicheartwouldslowdownandseemtoalmoststop,thenspeedupforafewbeats.Theelectromyogramswereratedona5-pointscalebycomparingthemtoasetofstandardrecordsrankedfromextremerelaxationto

comparingthemtoasetofstandardrecordsrankedfromextremerelaxationtoviolenttremor.

Whenpossible,ratingswereconvertedtostaninestofacilitategroupcomparisons,butsomedistributionsweretooskewedtopermittransformation,sothatcomparisonsweremadeintermsoftheproportionofeachpopulationrespondingatalevelarbitrarilycalledhigh.Eventuallyweused18specific-responseratings(Table8.1).Inaddition,compositescores(sumofscoresonallovertbe-

TABLE8.1SpecificResponseRatings

havior)werecomputedforthecontrolepisodesalone,forreactionstothebell,andfortheshockepisode.Ahandler-effectscorewascalculatedbasedonthenetchangeintotalscorebetweenstimulationperiodsandcontrolperiods.Somedogsweremoreactivewhenalonethanwhenstimulated;inothers,thereversewastrue.Wewerelookingforevidencethatsuchresponsescouldbeaffectedbyheredity.

■I

RESULTS

:tychangesassociatedwithage.—Changesintotalscores

fromoneagetoanotherwerenotspectacular.AsshowninFigure

•eagles,andbasenjisareconsistentlymoreemotionally

-nansheltiesandcockersatallthreeages.Specificratings

7-

z

it

CD

1734

5

5

elI-—.•.:dtthefivepure:..three

^nkdefinitelyhigherthantheo::

showedsimilarresults.Terrierswerehighontremorandpantingatallagesandlowonvocalization.Infact,themeansofeachbreedremarkablvconsistentinviewoftherelativelylowcorrelationsbetweenratingsonsuccessivetests.TetrachoriccorrelationsbetweenratingsatI"34weeksrangedfrom.063to.SISwith

amedianof.333.Correspondingfiguresforscoresat34and52weeks

219I_vithamedianof.532..Althoughmor.

relationswerestatisticallysignificanttheyweretoolowtobeofvalueforprediction.Actuallythemeanofitsbreedisoftenabetterpredictorofanindividualsscorethanitsscoreonapre-vio

:^nificantl}betweenthethreetests.Except-ntingwasmuchmoreprevalentat17and34weeks.

EMOTIONALREACTTVTTY

199

Liplickingdeclinedinallbreedsexceptbasenjis.Furthermore,youngerdogstendedtobemoreactivewhenanexperimenterwaspresentinthecubicle;olderdogsweremoreactivewhentheexperimenterwasoutside.

TABLE8.2

••P<.01

Inallbreedsheartratesdeclinedwithage.fromapproximately220beatsperminuteatoneweekofageto130atoneyear(seeFig.5.1).Therelativepositionsofthebreedsremainedfairlyconstantfrom17weeksthroughouttherestofthefirstvear.Theintraclasscorrelationforcontrolperiodheartratewashighestat34weeks,indicatingasomewhatgreatereffectofgeneticdifferencesatthisagethanwitheitheryoungerorolderanimals(Table8.2.

atthisagethanwitheitheryoungerorolderanimals(Table8.2.

InTable8.3arechangesinheartrateaccompanyingtheentrance

TABLE8.3ChangeenHeartRate(BeatsMinute)DuringQuieting

P<.01

ofanexperimenterforEpisode3,quieting.Inthesedatathebreeddifferencesaregreatestat17weeks,whenthecockerspanielsshowedamaikeddropandthewire-hairedterriersasimilarincrease.Onthelatertestsbasenjisandbeaglesconsistentlvshowedcardioac-celeration,whilespanielscontinuedtoshowdecelerationunderthesameconditions.Incontrast,theheartrateresponsesofthesheepdogsandterriersareinconsistentatdifferentagesandwithinbreeds.Thesmallaveragechangeforterriersdoesnotindicatethatallmembersofthisbreedmaintainedaconstantheartratewhenthestimuluswaschanged.Bothmarkedaccelerationanddecelerationwerefoundinafewindividuals,butthemeanwasclosetozero.

e=ee::z~zmces

TABLE8.4

MeanStanineScoresorFivePureBreedsonTenBehavioralandFourHeartRateMeasuresatThreeAges

Breedcomparisons.—Tables8.4and8.5summarizereactivitytestscoresforthefivepurebreeds.InTable8.4aremeasureswhichwereconvertibleintostanines,togetherwiththeresultsofanalysisofvarianceofthetransformedscores.Readersinterestedincomparingthesignificanceofdifferencesbetweenpairsofbreedscanusetheapproximationthatdifferencesof1.0stanineunitswilloccurinabout5percentofcomparisonsinarandomsample.Forexample,thefirstfourbreedsareseparatedfromeachotherbyadifferenceofoneormoreonthetotalbehaviorscoreat17weeks.Foxterriersareintermediatebetweenbasenjisandsheltiesandthusarenotsignificantlydifferentfromthesetwobreeds.Thismeansthat8outofapossible10interbreedcomparisonsaresignificantlydifferentat5percentorbetter.

Perhapsthemoststrikingfeatureofthistableisthealmostuniversaloccurrenceofhighlysignificantdifferencesbetweenthefivebreeds.Thirty-onedifferencesoutof42aresignificantatthe.001level.Onlyheartratechangeduringbellringingandthehandler-effectscorefailasdiscriminatorsofbreeddifferences.A

ringingandthehandler-effectscorefailasdiscriminatorsofbreeddifferences.Apreponderanceofsignificanteffectsofheredityhasnotbeenachievedbydiscardingmeasureswhichfailedtodiscriminatebetweenbreeds.Allofthemeasuresonwhichreliabledatawerecollectedhavebeenincluded.Itismuchmoredifficulttofindscoreswhicharenotaffectedbybreeddifferencesthantofindthosewhichareaffected.

InTable8.5aresetforththeresultsofmeasurementswhichwerenotsuitableforstanineconversionbecauseofskewnessofdistributions—usuallytheoccurrenceofmanyzeroscores.Evaluationofthesignificanceofdifferencesbetweenbreedswasaccomplishedbythechi-squaremethod,andcontingencycorrelationswerecalculatedinordertocomparedegreesofhereditaryinfluence.Aswiththemorenormallydistributedscores,differencesbetweenbreedswerehighlysignificantonallmeasuresexceptthatofelimination,wheretheincidencewastoolowforasatisfactorystatisticalcomparison.

Itisinstructivetocomparethevaluesoftheintraclasscorrelationsateachage.Overtwo-thirdsofthesecorrelationsfallbetween.15and.45.Themedianvaluesatsuccessiveagesare.23,.27,and.29.Thusweinferredthattheproportionateeffectofheredityonallscoresconsideredtogetherismuchthesamebetween17and51weeks,althoughcorrelationsforindividualmeasuressuchastheheartratemayriseandfall.Thereissomepossibilitythatgeneticdifferencesareexpressedmoredefinitelyintheone-yearphenotype,ashighintraclassandcontingencycorrelationsoccurtwiceasoftenat51weeksasateitheroftheothertwoages.

1-zlZZF-RENCES

TABLE8.5

PercentagesofSubjectsExceedingArbitraryThresholdsonEightMeasuresinReactivityTest

•Thresholdsforgroupingscoresonliplicking,resistancetoforcedmovement,andlatency-ofemergencewerenotthesameatallagesbecauseofdevelopmentalshiftsinaveragefrequencyofoccurrence.

Sinceasubstantialportionoftheobservedvariationinreactivitywasnotcorrelatedwithbreeds,wemayinquireintocausesotherthanheredity.Hadthepurebreedsbeenhighlyinbredsoastobenearlyhomozygousatallloci,wecouldconcludeonthebasisoftheintraclasscorrelationsthat55to85percentof

couldconcludeonthebasisoftheintraclasscorrelationsthat55to85percentofthevariationsinthetestmeasureswasattributabletoenvironmentalfactorsactingtodifferentiateindividuals.Eachbreed,however,wasactuallyfairlydiverseingenotypesothatthecalculatedcorrelationsareminimalestimatesofgeneticinfluences.Environmentalfactorswereprobablvnotasimportantastheabovefigureswouldimply.

Stillanotherapproachistoinvestigatetheeffectsofsexandoflitterinfluencesonthetest.Amongthepurebreeds,totalreactivityscoresofma)lgcd4.9onthestaninescale;femalesaveraged

EMOTIONALREACTIVITY203

5.0.Thetwosexesgavealmostidenticalresults,indicatingthatthisformofhereditaryvariationhaslittleeffectonthescores.Ontheotherhand,therearesignificantdifferencesbetweenlitterswhenallthreetestsaregroupedtogether.Ourexperimentaldesigndoesnotpermitallocationofthesourceofthiseffect,butsomeorallofthefollowingmaybeinvolved:specificgenesfromaparticularsetofparents,maternalcaredifferences,climaticchanges,changesinobservers—infactanyvariablewhichmightbemorealikeformembersoflittersthanfordogsingeneral.Removingthelittereffect,however,doesnotinthisinstancedecreasethebreeddifferences.Theintraclasscorrelationforbreeds(basednowuponlittermeans),is.61,denotingremarkablylargehereditaryeffects.

Interpretation.—Afteremphasizingdifferencesbetweenbreedsintheformandintensityofemotionalexpression,wewishtocautionthereaderagainstacceptingtheideaofabreedstereotype.Typicallytherangeofscoresforabreedextendedover5or6points,andoccasionallyovertheentire9pointsofthestaninescale.Basenjisandcockerspanielshadmeanstaninesof6.00and3.03,respectively,atoneyear;but65percentofthebasenjisand41percentofthespanielsoverlappedinthemiddlerangeof4to6.

Noone-year-oldterrierwasratedbelow6ontremoralthoughallotherbreedshadindividualswithlowscores.Althoughterriersdidnothavescoresinthelowzone,theotherbreedswerenotrestrictedinthisway,andratingof7and8werecommoninfour.Theleastamountofoverlapwasfoundinbitingatoneyear;83percentofbasenjiswerebitersand93percentofcockerspanielswerenon-biters.

Themostgeneralinterpretationofthesedifferencesbetweenbreedsisthatthey

Themostgeneralinterpretationofthesedifferencesbetweenbreedsisthattheyarerelatedtodifferentialresponsestoinhibitorytraining.ThisisparticularlyevidentinFigure8.1,inwhichthecockersandsheltiesrankedconsistentlybelowtheotherbreeds.Boththesebreedsareeasilytrainedtorepressanyactivity,althoughtheresponsestakequitedifferentforms.Anysortofthreat,butparticularlyahandmotion,willmakeacockerceaseallactivity,buttheeffectismomentaryandtheanimalshowsnosignsofemotionaldisturbance.Inhibitionofasheltieislonglastingandappearstobeaccompaniedbyprolongedemotionalarousal.

Thisbringsuptheproblemofwhetherthereactivitytestmeasuresasingleunderlyingtrait,oracompositeofgeneticallyinfluencedcapacities.Manyofthescoresarepartiallycorrelatedwitheachother,andtwoofthemeasures,heartrateandsinusarrhythmia,arehighlyinterdependent.Aslowheartrateisarrhythmicand,con-

204BREEDDIFFERENCES

versely,afasterheartrateisregular.Afactorialanalysis,aswillbeseeninchapter14,resultedinsplittingthevariousreactivitymeasuresamongseveralfactors,heartratebeingone,andageneralfactorforconfidence-timiditybeinganother.

SUMMARY

Theemotionalresponsescharacteristicofthedifferentbreedscontinuetochangeanddevelopthroughoutthefirstyearoflifesothatbreeddifferencesonthereactivitytestwerepresentandhighlysignificantinastatisticalsenseatallages.Thetestsituationsseemtoaccentuateemotionaldifferencesbystimulatingdistinctalternateresponses,suchaspassivityorattemptstoescape.Selectioninthepasthasobviouslybeenhighlysuccessfulinseparatingthefivebreedswithrespecttoalargenumberofemotionalresponses.Somuchvariationstillremains,however,thatitwouldprobablybepossibletoselectcockerspanielsforafewgenerationsandproduceoffspringliketerriersorbeagles—atleastwithrespecttoparticularresponses.Tosynthesizebythismethodatotalpatternofresponsessimilartoanotherbreedwouldbeamoredifficultifnotimpossibletask.

Allthisstronglysupportstheconclusionthathereditygreatlyaffectstheexpressionofemotionalbehaviorandalsothatdifferencesinemotionalbehaviorformaprominentpartofthecharacteristicbehaviorofbreedsandindividuals.

formaprominentpartofthecharacteristicbehaviorofbreedsandindividuals.ComparabledifferenceshavebeenreportedinhumanindividualsbyLaceyandLacey(1958).Whetherornotsuchdifferencesarerelatedinturntotheperformanceofbreedsintrainingandproblem-solvingtestsisaquestionwhichwillrecurinfuturechapters.

EXPERIMENTS

ONTRAINABILITY

Anumberofourproceduresinvolvedmodificationofadog'sbehaviortowardapatternspecifiedbytheexperimenter.Suchlearningdiffersfromproblemsolvingbyrequiringamorestereotypedresponsefromtheanimal,althoughthefundamentalprocessofselectivereinforcementofsuccessfulresponsesoperatesinbothtypesoftests.Itisthereforeconvenienttoseparatesuchtestsasquieting,leashtraining,retrieving,motorskills,andobediencefromproblem-solvingtestsinthemoreusualsense.

Trainingtestscaninturnbedividedintoforcedandrewardedcategories.Inforcedtraining,thetraineeispunishedforadeviantresponseorpreventedfromcarryingitout.Inrewardtrainingheisrewardedwhenhemakesthecorrectresponse.

Trainingtofollowapprovedculturalmodesisanimportantpartofchilddevelopmentandislikewiseimposeduponapuppyadoptedintoahumanfamily.Remainingquiet,walkingonalead,andsittingquietlyoncommandarepartoftheusualregimenofpetdogs.Ourproceduresweresimplystandardizedformsofsuchtraining,coupledwithanobjectiveratingscaleforperformance.Insuchforcedtraining,theexperimentersestablishedinadvanceapatternofbehaviorwhichwastoserveasamodelandsystematicallypunisheddeviations.Analogieswithcertainaspectsofchildrearingarefairlyclear.Trainingwascontinuedforaspecifiedperiod,andcomparisonsbetweengeneticgroupsweremadeatvariousstages.Rewardtrainingismorecloselyrelatedtoordinaryproblemsolvingsincethesubjectisfreertoadoptanyindividualmodeofrespondingwhichissuccessful.Thetasksinretrievingandmotorskills,however,involveaminimumofsensorydiscrimination;instead,theexperimenteren-

205

BREEDDIFFERENCES

BREEDDIFFERENCES

couragesandrewardsthesubjecttoperformrelativelysimpleacts.Parentssimilarlytrainachildtothrowaballorclimbstairs.

Thatthereareindividualdifferencesintrainabilityis,ofcourse,commonknowledge.Ourinterestwasindeterminingtheportionofvariabilityattributabletogenetics,andintherelationshipbetweentrainabilityandothercharacteristicsofthesubjects.Inparticular,wewereinterestedinwhethertrainabilitywascorrelatedmorecloselywithothermeasuresoflearningorwithmeasuresofemotionalresponse.

FORCEDTRAINING

Quieting.—Theearliestforcedtrainingaroseoutofattemptstoweighpuppiesaccurately.Itwasnecessarytokeepthemquietonthescaleswithoutactuallytouchingtheminordertotakeareading.Wedevelopedatechniqueofplacingasubjectonthescaleplatform,holdingourhandsnearbutnottouchinghimunlesshestartedtowriggleorstepoff.Thebestpossibleperformancewasforapuppytoremaininactiveforoneminuteofweighingandobservation.Ratingsweregivenoneachtrialasfollows:3,active;2,partlyactive;and1,quiet.

Figure9.1showstheresultsatdifferentages.Noneofthevery

i.o

.9.6

fc.7

z>

°.6

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P.5a:

24O4

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.2

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8910II12AGEINWEEKS

131415

Fie.9.1.—Proportionofanimalsratedasquietduringweighing.Thecurvesaresmoothedbytaking3-pointmovingaverages.

TRAINABILITY207

younganimalsremainedquietforawholeminute,butbeginningatabout5weeksofage,someindividualsinsomebreedsbegantodothis.Graduallymoreandmorewerecompletelytrained.Atfhesametimethebreedsbegantodifferentiate,sothatby16weeksnearly70percentofthecockerspanielswereremainingquietbutonly10percentofthewire-hairedfoxterriers.Sheltieswerethesecondmosteasilytrained,andbasenjisandbeagleswereclosetothemeanofthefoxterriers.

Leashtraining.—Trainingtowalkonaleadwasbegunat19weeksofage.Thepuppiesweregivenfivetrials(oneperday)overacourseleadingfromtheiroutsidepenstothelaboratory.Beginningonthethirdday,theywereledthroughaportionofthelaboratoryandupaflightofstairs.Thepuppiesworeachoke

aportionofthelaboratoryandupaflightofstairs.Thepuppiesworeachokecollarattachedtoachainleash.Ananimalwhichbalkedthreetimessofirmlythatitcouldnotbeinducedtocontinuewalkingwasliftedandcarriedbytheexperimenteroverthecourse.Thesubjectswereledbackoverthesamepath,butnorecordsweremadeoftheirresponsesonthereturnjourney.Asecondseriesoffivetrialswasgivenduringthetwenty-secondweekwhentheywereledtothelaboratoryfordiscriminationtraining.

Wewantedtotrainthedogstowalkonaslackleadattheleftoftheexperimenterwithoutvocalizationorbodilycontact.Demeritswererecordedforthefollowingfaults,withanarbitraiymaximumscoreononedayofthreedemeritsineachcategory.

Balksontheoutdoorcourse

Balksatdoorsorgates

Fightingorbitingleash

Draggingbehindorrunningahead(positionerrors)

Interferencewiththeexperimenter(bodycontacts)

Vocalization

Aconvenientwayofmeasuringtheeffectivenessofleashtrainingistheprogressivereductionofthetotalnumberofdemerits.Ofequalinterestisthefrequencyofoccurrenceoftheseveraltypesofdemeritsoverthewholecourseoftraining.Suchmeasuresprovedtobeparticularlysuitableforcharacterizingpatternsofresponsesforthefivebreeds.

Intheleashtest,unlikemostofourbattery,therewasnosignificantincreaseinreliabilityastrainingproceeded.ThisiswellshownbythetetrachoriccorrelationsbetweenthethreepairsoftestsrecordedinTable9.1.Thecorrelationswere:rtetlt2=.72;rtet4t5=.76;rtet9,io=.79.Althoughalmostallsubjectswerereceivingveryfew

BREEDDIFFERENCES

demeritsattheendofthetrainingperiod,theywerenomorepredictablefromdaytodaythantheywereatthestartoftraining.Thecorrelationbetweenthesumsofoddandeventrialswas.86,whichishighwhenoneconsidersthat

sumsofoddandeventrialswas.86,whichishighwhenoneconsidersthathandlerswerechangedonalternatetrials.

TheeffectsoftrainingonthenumbersofdemeritsinthefivepurebreedsareshowninTable9.1.Forsimplicity,onlysixofthetendaysaresummarized:thefirsttwo,thefourthandfifth,andthelasttwodays.Thesewerechosentoberepresentativeofthebeginning,middle,andlatestagesoftraining.

InspectionofTable9.1showsthatthemeansofthebreedscome

TABLE9.1MeanNumberofDemeritsinLeashTraining

closertogetherastrainingproceeds.Thus,therangeofbreedmeansonDay1was5.8demerits,andonDay10,2.1demerits.Onemightinferfromthisthattheeffectoftrainingwastodiminishtheimportanceofhereditarydifferencesuponbehavior,buttheconclusionwouldbeincorrect.WhentheproportionoftotalvarianceattributabletobreeddifferencesiscomputedforDay1andforDays6-10combined,therespectivevaluesare53.7and52.4percent,anegligibledifference.Thelastfivedayswerepooledinthiscalculationinordertomakethemeannumberofdemeritsmorenearlyequalforbothsetsofscores.Ingeneral,thedogsmadeaboutasmanyerrorsonthefirstdayastheydidduringthewholesecondweek.

Trainingfortherigidcriteriademandedbythistestdoesnoteliminatenorevendiminishtherelativecontributionofhereditytobehavioralvariation.Ofcourse,iftheprocesscouldbecontinuedtothepointwherenodemeritswereassigned,allindividualandbreedvariationwouldvanish,andhereditaryeffectswoulddisappear.Intin'stest,over50percentofthevariationinthetotalscorecouldbeattributedtobreeddifferences.Theproportionisunusuallyhigh,andthereforeitisInterestingtoanalyzethiscasefurther.

(raeobviouscourseistocomparethebreedsonthedifferenttypes

TRAINABILITY

209

ofdemeritsseparatelyinordertoseewhetherthegroupsdifferinnumberofdemeritsonly,orintheircategoriesaswell.Byconversiontostanines,itispossibletocompareeachtypeofdemeritonthesamescale.

Figure9.2showsthemeanstaninescoresforeachdemeritcategory.Itisclearthatbreeddifferencesinnumbersofbalksandposi-

BALKSINDOORS

VOCALIZATION

BABEACSSHWH

BABEACSSHWH

Fig.9.2.—Typesofdementsgivenduringleash-controltraining(staninescale).

tionerrorsarelessmarkedthaninfightingtheleash,interference,andvocalization.Basenjiswereoutstandingintheirvigorousresistancetotherestraintofacollarandlead;Shetlandsheepdogssimilarlyinterferedexcessivelywiththehandlerbyleapingonhimandwindingbetweenhislegs;beaglesweretheforemostemittersofhowlsandwailsduringinitialstagesoftraining.

Applyingananalysisofvariance,wecancomputefortheseveral

BREEDDIFFERENCES

BREEDDIFFERENCES

demeritcategoriestheproportionofvariationattributabletobreeddifferences.Thesevaluesare:balksintheopen,1.9percent(notsignificant);balksatdoors,28percent;fightingtheleash,72percent;outofposition,39percent;interference,55percent;andvocalization,40percent.Alldifferencesexceptthefirstaresignificantatbetterthanthe.01level.

Thepatternofintercorrelationsbetweenthesixtypesofdemeritsshowssomestrikingrelationships.ThesehavebeenarrangedinTable9.2tobringthelargercoefficientsofcorrelationalongthemain

TABLE9.2IntercorrelationsofTypesofDemeritsDuringLeashTraining

diagonal.Suchanarrangement,accordingtoGuttman(1955),showsthedegreetowhichtheseveralkindsofdemeritscanbeconsideredasexpressionsofcommonfactors.

Intercorrelationsbetweenthetwotypesofbalksandpositionerrorsarethehighestandseemtodefinethecentralcharacteristicsofthemodeltowardwhichtrainingisdirected,thatis,adogwalkingfreelyontheleashbythesideofthetrainer.Thedemeritswhichmoststronglyseparatethebreedsareperipheraltothiscorecharacteristicandmaybeinterpretedasalternativeformsofemotionalresponsetothesituation.Demeritsforinterferencecorrelatenegativelywithallothertypes.Byaddinginterferenceratingstoobtainatotaldemeritscore,wetendedtounderstatebreeddifferences.

Althoughtrainingreducesthenumberofdemeritsinallcategories,itdoesnotdosoequally.Theproportionofbalksandvocalizationfalls,buttheproportionofpositionerrorsandinterferenceincreases.DetailsaregiveninTable9.3.Thusthehereditarydifferencesatthebeginning,middle,andendoftrainingareexpressedindifferentbehaviorpatterns.Ifonlythetotalscoresarecompared,thisinterestingfactisconcealed.

Weconcludethaieachbreedischaracterizedbyapatternofresponseswhicharedifferentiallyaffectedbytraining.Astrainingproceeds,theexpressionofhereditarydifferencesshifts,butthepro-

TRAINABILITY21

TABLE9.3TypesofDemeritsinEarly,Middle,andLatePhasesofLeash-

TABLE9.3TypesofDemeritsinEarly,Middle,andLatePhasesofLeash-ControlTest

portionofvarianceattributabletogeneticschangeslittleornotatall.Withinafewdays,subjectsaretransformedfrompuppieswhopulloffatwildanglesordragtheirfeet,emittingbloodcurdlingyelps,todocilecreatureswalkingfreelybytheirhandlers.Butthehereditarycontributiontoindividualityisdetectableatallstagesoftraining.

Theobediencetest.—Athirdmajorproceduredesignedtotrainsubjectstoachieveaspecifiedcriterionofbehaviorwastheobediencetest.Animalsweretrainedovera3-dayperiodtoremainonastandfor30secondsandthentojumpdownoncommand.Duringtheearlystageseachsubjectworeachokecollartowhichaleadwasattached.Astrainingprogressedrestraintsweregraduallyremoved,andthehandleronsuccessivetrialsmovedawaytodistancesof1.5,3,6,and12feet,andfinallybehindascreen14feetfromthestand.

Ifthesubjectleapedprematurelyduringatest,thehandlermovedclosertothestandforthenexttrial,andstartedanewseriesofincreasing-distancetrials.Ameasureoftheleveloftrainingattainedoneachdaywasobtainedbyarbitrarilyassigningascoretothesubject-trainerdistanceandaddingthescoresofaday'strials.Assignedvalueswere:chokecollar(0);6inches(1);1.5feet(2);3feet(3);6feet(4);12feetandbehindscreen(5).Subjectswhofailedtoleapatcommandwithin10secondsweregentlypushedfromthestandbythetrainer.

Thetrainingprocedurewasdesignedtobringindividualstoacommonstandardasquicklyaspossible.Equalizationwaspromotedbycountingtwochoke-collartrialsasequivalenttoasinglehand-controltrialinscoring.Thusthemorerecalcitrantsubjectsreceivedadditionaltraining.Inaddition,trainingwasdiscontinuedonanydaywhenthesubjectstoodfor30secondswiththehandleratthe12-footmark.Thiswasdonetoavoidovertrainingsubjectsandtherebyincreasingtherangeofindividualvariation.

OnDay4and,formostsubjects,againonDay5,astandardized

212BREEDDIFFERENCES

setoffivetrials,oneeachat0.5,1.5,6,and12feetandbehindthescreen,wasrepeatedtwice.Procedurewasthesameasintraining,exceptthatnopunishmentwasgivenforprematureleaping.Acompositescoreforthetestwasobtainedbyaddingthetimespentonthestand,plus30foreachtrialinwhichthesubject

addingthetimespentonthestand,plus30foreachtrialinwhichthesubjectjumpedoncommand,plus60foreachtrialinwhichthesubjectdelayedfor10secondsfollowingthecommandtojump.Scorescouldrangefromzeroforasubjectwhoalwaysleapedfromthestandimmediatelyuponrelease,to450forasubjectwhofailedtojumponcommandinallfivetrials.Theoptimum"obedience"wouldbeascoreof300.However,theresultsmadelesssensewhenarrangedaccordingtoascaleof"obedience"thanwhenarrangedaccordingtoascaleofinhibitionofmovement.Inoursystem,therefore,highscoresdenoteinhibitedsubjectswhichremainedimmobileonthestand;lowscoresdenotehyperactivesubjectsnotwellcontrolledbythehandler;andmiddle-rangescoreswereobtainedbydogswhichwerereadilycontrolledbythehandler.Resultswereconvertedtothestaninesystem.

Inaddition,twootherratingsweremadeonmostofthesubjectsinthetestsituation.Ameasureof"confidence"wasobtainedbynotingwhetherthedogwouldeatfromadishplacedfirstonthestand,thenbesideit,andfinallyatsomedistance.Somedogswouldnottakefoodatall.Ameasureof"attraction"wasobtainedbyratingthesubjectonhisapproachtothehandlerbetweentrials.Eachdogwascalledbythehandlerafterhehadfinishedrecordingeachtrialonthedatasheet.Resultsofthesetwomeasurescouldnotbeconvertedintostanines,andsubjectsweremerelyclassedaslow,medium,andhighwithrespectto"confidence"and"attraction."Theobjectinrecordingthesemeasuresofemotionalandsocialbehaviorwastoseewhethertheyhadanyconsistentrelationshipwithdegreeoftrainability.

Finally,aspecialprocedurewasadoptedduringtheprogramtotesttheeffectsofchanginghandlers.Eachlitterwasassignedtotwohandlers,onemanandonewoman.Withineachbreedorhybridgroup,maleandfemaledogsweredividedseparatelyatrandombetweenthehandlers.Amongthepurebreeds,theretestonDa\5wasconductedbytheotherhandler;amongthehybrids,theretestwasadministeredbytheoriginalhandler.Thisdesignpermitsevaluationoftheefficacyofmaleandfemaletrainersandtheextenttowhichobediencetrainingisgeneralizedasaresponsetohumanbeingsascontrastedwithspecificindividuals.Onewouldpredictthattherewouldbesonicdeteriorationofperformanceonretestwithanotherhandlerandpossiblythattheeffectwouldbemoreextremeinbreeds

TRAINABILITY

213

withthenameofbeingone-mandogs.Amongoursubjects,thebasenjishavesuchareputation.

Allthebreedsshowedmarkedimprovementoverthethreedaysofpreliminarytraining.Figure9.3demonstratesthattheorderofper-

6-

5-

I23

DAYS

Fig.9.3.—Leveloftraining(stanineunits)onsuccessivedaysofobediencetest.

formancedoesnotshift;infact,thespreadofthemeansincreaseswithtraining.Theproportionofthetotalvarianceattributabletobreeds,ft,alsoincreases,butnotsignificantly.Thesameorderofbreedscoringwasmaintainedonthetestdayandintheretest.ResultsofbothtestsareshowninTable9.4.Differencesbetweenbreedswereagainhighlysignificant,withintraclasscorrelationsinthefirsttestof.149,andonretest,.262.

Thereliabilityoftheindividualscoresontestday(Day4)canbeestimatedbythecorrelationof.939betweenthetwohalvesofthetest.Thecorrelationbetweentestandretestwas.863.Thesefiguresindicatethatafewdaysoftrainingproducehighlyconsistentbehaviorontheobediencetest,evenmoresothanintheleash-trainingtest.

Itisinterestingtonotethattheaverageperformanceofdogstrainedbymenandthosetrainedbywomenwerealmostexactlythe

214BREEDDIFFERENCES

TABLE9.4MeanStanineScoresonObedienceforPureBreeds

Breed

Basenji

Beagle

Beagle

Cockerspaniel

Shetlandsheepdog...Wire-hairedfoxterrier

All

SexofExperimenter

Day4

Day5

F

MFMFMFMFM

MFM

FMFMFMF

FM

M

F

N

115

10

11

13

11

9

10

10

5

8

4845

MeanScore

Day4

4.003.20

4.905.505.806.506.505.056.606.19

5.425.47

Day5

3.403.20

4.254.455.416.045.504.706.205.44

Difference

betweenDay5-Day4

-0.600.00-0.65-1.05-0.39-0.46-1.00-0.35-0.40-0.75

4.824.88

0.600.59

same(5.47and5.42,respectively).Theaveragechangeinscoreonretestwasalsopracticallyidentical(—0.60)whetherthechangewasfrommaletofemaletrainerortheopposite.Thehybrids,whowerere-testedbythesameindividual,felllessthanhalfasmuch(—0.27)onretest.Theseresultswouldhavebeenpredictedontheargumentthatanychangeinthetestingsituationwouldproducedetrimentaleffectsuponperformance.Wefoundnoindication,however,thatanyonebreedwasmoreaffectedthananotherbreedbythechangeinexperimenters.Thenumberpergroupisrathersmall,buttheexperimentdoesnotsupportthenotionthatsomeofthetestedbreedsattachthemselvesonlvto

notsupportthenotionthatsomeofthetestedbreedsattachthemselvesonlvtooneindividual,whileothersshifttheirresponsesreadilytoanotherperson.

Itwassomewhatsurprisingtofindthatperformanceontheobediencetestasmeasuredbythetendency7toinhibitjumpingwascorrelatedneitherwithourmeasureof"attraction"norbv"confidence."Strikingbreeddifferenceswerefoundinthesetworatings.Withinanyonebreed,however,highorlowconfidenceorattractionratingswereunrelatedtoobediencescores.Itisperhapsoddthattrainingwasequallyeffectivewhetherornotthesubjectwasattractedtothetrainer,andwhetherornotthesubjectwaswillingtoapproachthestandtoreceivefood.Theresultssuggestthatthevariouspartsofthedog'sbehavioralrepertoiretendtobeindependent.Hisentirebehaviorisaffectedbygenotvpe,butgeneralfactorsoftrainabilityandemotionalityarenotreadilyfound.

Tosummarizetheresultsofthistest:

1.Breedsdifferwidelyintheeasewithwhichtheycanbetrainedtoremainquietoncommand.

TRAINABILITY215

2.Allsubjectslearnundertraining,butthedifferencesbetweenbreedspersist,atleastoveraone-weekperiod.

3.Thecontributionofhereditytototalvariancedoesnotchangegreatlyovertheperiodoftraining.

4.Changingtheexperimenterforaretestproducesamoderatedecrementinscore,whichisabovethatfoundwhentheretestisperformedbytheoriginalexperimenter.Theeffectisaboutthesameinallbreedsexamined,butgreatindividualvariationisfound.

Comparisonofbreeds.—Alloftheseforced-trainingtestsinvolveteachingtheanimaltobeinactive.Thepuppyistaughttostayquietlyonthescalesbyhandsignalsandrestraint.Whenplacedonaleash,heisbeingtaughttorestrainanyactivityexceptthatoffollowingtheexperimenter.Finally,ontheobediencetest,heistaughttobeinactiveonaplatformatadistancefromthetrainer.

Whenthebreedsarerankedonallthreetests(Table9.5),the

TABLE95RankofFivePureBreedsunderForcedTraining

TABLE95RankofFivePureBreedsunderForcedTraining

Test

ControlledActivity>•Overactive

ScaleactivityCSSHBABEAWH

LeashcontrolCSWHBABEASH

ObedienceCSWHBEASHBA

cockerspanielsemergeastheeasiesttotraininallthreesituations.Basenjisandbeaglesareconsistentlyhardtotrain,butsheltiesandwire-hairedfoxterriersmaydowellinonesituationandpoorlyinanother.

Weareforcedtoconcludethatthereisnosimplegeneralcapacityinvolvingrestraintforacceptingforcedtraining.Thetrainabilityofcockersisrelatedtotheirformerselectionfortheabilitytoaccepttrainingtocrouch.Thisresponseiseasilyelicitedbyhandsignals,andthesewereusedtosomeextentinallthreetests.Thesheltiesareeasilytaughtrestraintbydirectlytouchingtheirbodiesbuttendtobeactivewhenawayfromanexperimenter.Theydo,however,crowdagainsttheexperimenter'slegsduringtheleash-controltest.Wire-hairedterriersrespondtohandcontactwithplayfulfightingbutacceptrestrainttrainingatadistance.Ontheleashtheytendtopullaheadoftheexperimenter.Basenjisrespondtomostkindsofrestraintwithattemptstoescape,whilebeaglesgivetheappearanceofbeingrestlessinanyrestrainingsituation.Theseobservationsareborneoutbythelowcorrelationsbetweenthethreetests(Table

BREEDDIFFERENCES

TABLE9.6

CorrelationsbetweenTestsofForcedTraining(FromC.L.Brace)

•Sig.at.05**Sig.at.01

9.6).Theonlycorrelationofanyimportanceisaslightnegativecorrelationbetweenleashfightingandlearningtostayontheplatform.

Wethereforeconcludedthatthebasictrainabilitycharacteristicsofthedifferentbreedstendtobespecifictoparticulartestsituations,andthattheyarebasedon

breedstendtobespecifictoparticulartestsituations,andthattheyarebasedonalargevarietyofcapacities.Insometestsituations,thepossessionoftwodifferentcapacitieswillproducewidelydifferentresultsbetweenbreeds;inothersitmayproducealmostidenticalperformances.

REWARDTRAINING

Intheseteststheanimalisgivenarewardassoonasheperformsthedesiredact.Theusualtechniqueistobreakthetrainingdownintoaseriesofsteps,firstteachingtheanimaltodoasimplefirststep,thenaddingmoreandmorerequirementsinsequenceuntilacomplexseriesofactshasbeenlearned.ThisstepwisetraininghaslongbeensuccessfullyusedtotraincircusanimalsandhasbeendevelopedintoanartwiththetechniquesofoperantconditioningdevisedbySkinner(Skinner,1938;BrelandandBreland,1961).Foodisthemostcommonreward,butthedogisalsonotableforitsresponsivenesstowordsandattitudesofahumanhandler.

Inthesectionwhichfollows,wehavesummarizedresultsofthehabitformation,retrieving,andmotor-skilltests.Themotivationtestdescribedinchapter10asapreliminarytodiscriminationtrainingalsofallsinthiscategory.

Goalorientation(habitformation)test.—Thistestgivenwhenthepuppieswere9weeksofage,hadtwofunctions.Weintendedit

TRAINABILITY

217

asbasictrainingforrunningtoagoal(asafoundationformorecomplextests),andwealsoattemptedtomeasuretherapiditywithwhichapuppycouldchangeahabitonceitwasformed.Thetestitselfconsistedofshowingthepuppyasmallbitoffishinawoodenboxandthenplacinghiminacagewithawiregateinfrontasinthephotograph(seeplates).Theexperimenterlefttheroom,raisedthegatewithastringrunningthroughapulley,andrecordedthebehaviorofthepuppy.Thepuppywasgivenatotaloffourtrialsontwosuccessivedays,andthenthepositionoftheboxwaschangedtoadifferentcorneroftheroom,adistanceofabout6feet.Thepuppythenransixmoretrialsoveraperiodofthreedays.

AsFigure9.4shows,differencesbetweenbreedsweregreateron

SH\

GOALORIENTATION

56TRIALS

Fig.9.4.—Meantimescoresongoal-orientationtest.

thefirsttwotrialsthanonthethirdandfourth.Weselectedthesecondtrialforanalysis,inthehopesthatthiswouldproveameasureofbasicmotivationforrunningtoagoalafterthepuppieshadachancetolearntheobjectofthetest.Basenjisgavethebestperformance,andsheltieswerethepoorest.Asonmanyothertests,thebehaviorofthebeaglesshowedahighdegreeofvariability.Differencesbetweenbreedsweresignificant,buttheproportionofvarianceattributabletothiscausewasonly7percent(Table14.3).

Whenthepositionofthegoalwaschanged,largedifferencesbe-

tweenthebreedsreappeared,thebasenjisagainperformingbestandfoxterriersmostpoorly.Unlikeotherbreeds,sheltiescontinuedtoimprove,performingaswellasthebasenjis.Allthebreedsperformedverysimilarlyonthesubsequenttrials,andtherewasnoindicationofanvdifferencesintheabilitytoswitchfromonehabittoanother.

Thesuperiorityofthebasenjisonthegoal-orientationtestmayreflectsimplvtheirsuperiorrunningspeedatthis_tmore

probablyitshowsagreatertendencytowardvisualorientation.Therewasno

probablyitshowsagreatertendencytowardvisualorientation.Therewasnoindicationthatdifferencesbetweencockersandbasenjisshowedanyregularformofinheritance7;generalconclusionisthatallbreedsperformedinaverysimilarfashiononthissimplekindofrewardtraining.

7liningtoretrieve.—Mostdogscanbetaughttoretrieveastickandreturnittotheirma:houtanyapparentrewardother

thantheexecutionoftheactitself.Somedogs"beg"theirmasterstothrowobjectsforretrieval.Inaddition,manybirddogbreedsare

;JarlytrainedtoretrievewoundedorkilledbirdsandreturnthemtotheirmastersThecockerspanielhasinthepastbeenselectedforitsabilitytobetrainedinthisfashionandalsofora"softmouth,"meaningthatacockerwillpickupthebirdwithoutbitingorcrushingit

originallydidafewretrievingexperimentswith9-week-oldcockerspanielpuppies,anagewhensuchtrainingusuallysucceeds

Pfaffenberg.Thetrainingschedulebecamecrowd

however,andthetcostponedtoamuchlaterage(32wee*

trainedouranimalsbyusingamodificationoftheplay-retrievingprocedurewhichmostownersemploywiththeirdo^s.Anunfamiliarobjectwhichcouldbeeasilycarriedwasleftinthepenforacoupleofdaysinorderthatthedogsmightfamiliarizethemselveswithit.Onthesucceedingthreedavseachanimaltedforretrievalof

adumbell-likeobject(twothinblocksofwoodconnectedbvaheawwoodendowel'onatotalof9tri^

Theresultsweredisappointing.Only11percentofthepurebreddogsactuallyreturnedthedumbellandreleaseditinatleastonetrial,andnoneofthedifferencesbetweenbreeds.ificant

Moredetailedanalysisgaveasimilarresult.TheactofretrievingcanbebrokendownintosmallerbehaviorpatternsforpurposesofanTedogmustfollowtheobjectthrown,pickit

up,earn-it,returnit,and,finallyreleaseitwhenthetrainerattemptstotakeitavynearly100percentofthedosswouldfollowthe

ynearly100percentofthedosswouldfollowthe

object,andabout25percentwouldpickitupandcamit.butvervfewwouldactuallyreturnittothetrainer.Aâin.thedifferencesare

TRAINABILITY219

TABLE9.7

PercentageofAnimalsSuccessfullyTrainedinRetrievingTest

notgreatenoughtoindicatethatthereareanyimportantbreeddifferences.Occasionallyweobservedpuppiescarryingotherobjectsintheirmouthsaboutthepen—aspontaneousmanifestationofpartofthecompletepattern.However,therarityofsuchobservationspermitsnoconclusionsregardinggeneticorenvironmentalcausation.

Weconcludedthattheabilitytolearnretrievingisratherwidelydistributedthroughoutdogbreedsandthatthespecialabilitiesofthecockerspaniel,ifany,areconfinedtoretrievingbirdsinthefieldratherthantheplayretrievingwhichwastheobjectofthetest.Wewerealsoimpressedwiththerelativedifficultyoftrainingtheolderanimalscomparedtothefewwhichweretrainedat9weeks.Thereispossiblyacriticalperiodforlearningtoretrieve,thatis,atimewhentheprobabilityofexecutingthecompletepatternisrelativelyhigh,sothatrewardtrainingcanbemaximallyeffective.

Themotor-skilltest.—Aboutone-thirdofthewaythroughtheexperimentweobservedbasenjisjumpingtothetopsoftheirhousesandsurveyingtheworldfromthesevantagepoints.Somemembersofthisbreedcouldscramblehalfwayupthefenceoftheirenclosureandclingtoanarrowshelfwhilepeeringthroughthewiremesh.Noneoftheotherpurebreedsdidthis,andwethereforedesignedatesttomeasuredegreesofclimbingandjumpingcapacity.

Themotor-skilltest,asitwasnamed,requiredthedogstoclimbtothetopofapileofboxes,andlatertocrossabridgeleadingfromthepiletoanotherhighpointinordertoobtainafoodreward.Onthefirstdaywestackedtwowoodenboxesinthepenandplacedadishcontainingaspoonfuloffishuponit.Abroadrampledtothetop,andtheheightof2feetwasjustenoughsothatadogcouldnotreachthefoodfromtheground,andmusteitherjumptothetoporclimbtherampinordertoeat.Wefirstplacedeachsubjectinturnonthepileandallowedittoeat,thenplaceditbackonthegroundand

ittoeat,thenplaceditbackonthegroundand

measuredthetimerequiredtoreachthetopagain.ThetestwasrepeatedonDav2,andonDav3wasmodifiedbyincreasingtheheightto3feet.Asthepilegrewhigher,theramp,ofcourse,grewsteeper.OnDay4thestacksofboxeswere4and5feethigh,atwhichpointthetestbecamemostdifficult.OnDay5thestackwasreducedtothe3-footlevel,butthedogsnowhadtowalkacrossaplanktoreachthefood6feetawayonthetopofthehouse.Theplankwasatfirstonefootwide,andonthesecondtrialwasreplacedbyoneonly6incheswide.Manydogsfoundthisdifficult,andsomelosttheirfootingandfelloff.

Ifadogdidnotreachthegoalaftertwominutes,theexperimentertookaleashandledhimuptherampsothathecouldeat.Thus,forcedtrainingwassecondarilycombinedwithrewardtraining.

Thewholetestmayalsobeconsideredthecanineequiyalentofanathletice\entsimilartoahighjump.Theearlypartofthetestonthelowboxesconsistedoftrainingtheanimalsinmotiyationandinthetechniqueofclimbingandjumping,whilethelasttwodayswereequiyalenttoacontestinwhichtheheightoftheobjecttobeclimbedwasgraduallyraisedtooneofconsiderabledifficulty.

rfinedasfailuretoreachthefoodwithintwominutes.

lateverthecause,weresomanythattheresultsofthetestarebestexpressedintermsofpercentagesofsuccessratherthantimeF§9.5.Asexpected,thebasenjisdidbetterthananyotherbreedonthefirsttrialofthetest:butunexpectedly,diecockerspanielsdid

3A5-;-:'.■---;-

'CCr**2BOXES—>*B:>E:->=:>:$3:»iS=L~'»--_-'.•"

ZQ

MM

"60

<->40

a:

Q.

I23456789

TRIALS

Fig.9.5.—Proportionofanimalssucceedingoneachtrialofthemotetest.

TRAINABILITY221

equallywellonthetotaltestresults(Table9.S).Thebasenjisobviouslyhadsuperiorclimbingability,butthecockerswereturninginanequallygoodperformance.Whatactuallyhappenedwasthatthebasenjisreactedsuspiciouslytothestrangeobjectsplacedintheirpen,andtendedtoapproachtheboxesslowlyandcautiously,finallyjumpingorclimbingtothetop.Theyalsoshowedverylittleim-provementinpreliminarytraining.Ontheotherhand,thecockersshowednofearofthetestequipmentandusuallybackedoffandranrapidlyattherampsothattheirmomentumwouldcarrythemtothetop.Theresultwasthatthecockersactuallyhadalowerpercentageoffailuresthanthebasenjis,exceptonthefirsttrialandonthehighestsetofboxes.Beaglesandfoxterriersfellintosecondrankwithaboutthesamepercentageoffailures.Bothbreedsshowedupbadlyonthe4-and5-footstacks.TheShetlandsheepdogswereoutstandinglypoorallthewaythroughthetest,apparentlybeingquitefearfulofheightsandbeingrelativelylittleinterestedinthefoodrewardundertheseconditions.Theywereapproximately95percentunsuc-

cessfulonthemostdifficultpartsofthetest.Theoyer-allresultscanbeevaluatedbythechi-squareanalysis.Significantbreeddifferenceswereobtainedonalltrialsat5feet(P—.001).

Themostinterestingpartoftheseresultsisthewayinwhichtheanimalsorganizedtheirabilitiestomeettheactualsituation.Thebasenjiswiththeirsuperiorheightandjumpingabilitywereobviouslysuperiorinclimbingability.Yetthecockers,byorganizingtheirowncapacities,wereabletocompetesuccessfullyexceptunderthemostextremeconditions,andeventhenthedifferenceswerenotgreat.Onthemostextremetest,withtheboxesstackedto5feet,62percentofthebasenjissucceededagainst44percentofthecockers,adifferenceofonly18percent.Thetestisnot,therefore,afavorableoneforgeneticanalysisthroughthecrossbreedingexperiment.Nevertheless,theperformanceofthehybridswasofconsiderableinterest.TheFihybridsdifferedconsiderablyfromeachother

222BREEDDIFFERENCES

andtendedtoresembletheirmothers.Thebasenjibackcrosseswereverysimilartobasenjis,andtheF2'ssomewhatintermediatebetweenthetwobreeds.Thebackcrossestothecockersmadebyfarthebestrecordsinthepreliminarytrainingphaseoftheexperiment,butmadetheworstrecordonthemostdifficulttrial.Wemayconcludethattherearetwogenetictendenciesoperatinghere.Oneisthecapacityofthecockertorespondquicklytothetypeofmotivationaltrainingusedinthisexperiment,andtheotheristheclimbingandjumpingabilityofthebasenji.Thesetwointeractincomplexways.

SUMMARY

Theresultsofalltrainingtestsindicatethattheabilitytorespondsuccessfullytotrainingishighlyspecific,withtheresultthattheexpressionofanyoneabilityishighlydependentuponthetypeoftrainingused.Furthermore,itappearstobeextremelydifficulttodeviseatestwhichmeasuresonlyonesimplecapacity.Evenwhenthepuppieswerebeingtrainedtobequietonthescales,thecockerspanielsrespondedwiththeirtendencytosit,whilethefoxterriersemployedanothercapacity,thatofreactingaggressively.Theleash-controltestbroughtoutboththecharacteristicresistancetorestraintofbasenjisandthesheepdogtendencytocrowdnexttoaperson,ortoasheep.Inshort,inanyparticularsituation,apuppyorganizesthecapacitieswhichithappenstopossess,usuallyselectingthecombinationwhichgivesthebestresults.Thiswasespeciallyevidentinthemotor-skilltest,inwhichcockerspanielswereabletocompensateforalackofjumpingabilitybysuperiormotivationandeffort.

Whereithasbeenpossibletomeasurethecomponentsofbehaviorinvolvedin

Whereithasbeenpossibletomeasurethecomponentsofbehaviorinvolvedintraining,itisobviousthatemotionalreactionshaveahighlyimportanteffect.Suchreactionsappearnotonlyinthespecialsituationsdevisedtotestthem,asdescribedinchapter8,buttheyalsoeitherfacilitateorinhibittrainingofalmostanysort.

Theimportanceofbreeddifferencesvariedfromtesttotest,rangingfromverylargedifferencesintheleash-controlteststononeinretrieving,althoughinthelatteritmighthavebeenpossibletodemonstratedifferencesbyselectingamorefavorableagefortraining.

Traininghasvariouseffectsupontheexpressionofbreeddifferences.Inthequietingtest,trainingactuallyincreasedthemagnitudeofdifferences.Inmosttests,themagnitudeofdifferenceswasdecreased,buttheproportionofvarianceattributabletobreedmight

neverthelessremainconstant,asitdidintheleash-trainingandobediencetests.Demandingahigherdegreeofperformanceafterpreliminarytrainingmayincreasethemagnitudeofdifferences,asitdidinthemotor-skilltest.

Finally,eachtestoftrainingbroughtoutindividualconclusionsofgreatinterest.Theobediencetest,forexample,showedthatdogsofallbreedstendtogeneralizetheirtrainingfromonehandlertoanother,givingnosupporttothe"onemandog''theorv.Whethersuchdogsactuallyexistinotherbreedsindependentofdifferentialtrainingisanopenquestion.Theleash-trainingtestshowedbreeddifferencesthroughouttheperiodoftraining,buttheforminwhichthesedifferenceswereexpressedvariedastrainingprogressed.Inshort,theeffectofhereditvupontrainabilitvishighlycomplex,bothbecauseofthenumberofspecificbasicabilitiesinvolvedandbecauseofthecomplicatedinteractionbetweenthemmadepossiblebybehavioraladaptation.

THEDEVELOPMENTANDDIFFERENTIATIONOFPROBLEM-SOLVINGBEHAVIOR

Anewbornpuppycannotsurvivewithouttheconstantcareofitsmotherorofaconscientioushumancaretakeractingasasubstitutemother.Untilthepuppyemergesfromthenestboxatabout3weeksofage,lifeoffersfewchallengesandweseelittleevidenceofproblemsolving.Thisdoesnotmeanthatthepuppylearnsnothingduringthese3weeks.Thereissomeevidencethatsimplediscriminationsareacquired,andweknowthatmaturationofthesensoryandmotorsystemsisoccurringduringthistime.Thepointisthatunderordinary

motorsystemsisoccurringduringthistime.Thepointisthatunderordinaryconditionsproblem-solvingbehaviorisnotconspicuousandishardtodemonstrateunderexperimentalconditions,perhapsbecausecriticaltestsaredifficultinananimalwithrestrictedresponsecapacities.

At3weeksofagealargenumberofbehavioralchangesoccur.Ofparticularimportanceistheappearanceofthecapacitytoformstableconditionedreflexeswithrapiditycomparabletothatofanadult.However,theretinaisstillundeveloped,andthepuppyisunabletoperceivedifferencesindepthuntil4weeksofage.ChangesinthealpharhythmoftheEEGindicatethatfullvisualcapacityisnotreacheduntil7to8weeks.Moreover,motorabilitiesarestillundeveloped,sothatapuppyisclumsyandtireseasily.Consequently,6weeksofageisveryclosetotheearliestpracticaltimeforadministeringaproblem-solvingtest.Forthenextfewweeksthepuppyisremarkablyadaptableandresponsivetoalmostanysortoflearningexperiencewhichhisdevelopingmotorcapacitiesandshortattentionspanwillpermit.

By4monthsthepuppyliasdevelopedintoanindependentcreaturewhocanfindhisownfood,negotiatecomplicatedpathways,and

224

PROBLEM-SOLVINGBEHAVIOR225

ingeneralcopewithordinaryenvironmentalchallenges.Thepuppyatthisageis,ofcourse,fartooyoungtohaveacquiredthespecializedabilitiesforwhichdogsarefamous,abilitiessuchassheep-herding,guidingtheblind,orperformingincircuses.Hecan,however,beeasilytrainedtoobevsimplecommandsandcansolvecomplicatedproblemsprovidedthatnohighlydevelopedmotorskillsorgreatendurancearerequired.

Eventhesimplesttrainingmaybeconsideredasaformofproblem-solvingbehavior.Fromamultitudeofpossibleresponses,thepuppymustlearntoselectthosebringingthelargestorthequickestrewardandtoavoidthosewhichresultinpainordiscomfort.Severaltrainingprocedureswereconsideredinthepreviouschapter.Hereemphasisisplaceduponmorecomplicatedtestsinvolvingspatialrelationshipsandvisualcues.Attentionwillbegivenalsotothebarriertest,manipulationtest,andthemazetest,whichwerecarriedoutwithyoungersubjectsinanefforttolearnmoreaboutthedevelopmentofproblem-solvingability.

DEVELOPMENTOFPROBLEM-SOLVINGBEHAVIOR

Severaldifficultiesbesettheinvestigatorwhoattemptstostudythedevelopmentoflearningintheyoungpuppy.Thenewbornsubjecthasfewsimpleresponses,andonecandemonstratelearningonlybyanincreaseordecreaseinthefrequencyofoneofthesefewpatterns.Inolderpuppies,thecapacitiesforresponseareenormouslygreateranditiseasiertoshowwhetherornotaparticularresponseoccursasaresultoflearning.

Itisdifficulttonotetheexacttimeoftheappearanceofanyparticularlearningcapacity.Complextaskscannotbemasteredsuddenlyevenbyexperiencedsubjects,andattainingacriterionlevelrequiresmanytrials,oftenspacedoveraconsiderableperiodoftime.Shouldweestablishourcriterionofmaturationasthedayonwhichthepuppyfirstmeetsourstatisticalrequirementforlearning,orasthedayonwhichtrainingisbegun?Ifittakesapuppy2weekstodemonstratethathehaslearnedaparticulartask,wecannotdeterminetheageatwhichtheabilitywasacquiredmorepreciselythansometimewithinthe2-weekperiod.Obviously,greateraccuracyispossiblewhentestingisrestrictedtosimpleproblemspotentiallysolvablewithinafewtrialsconductedinoneday.Undersuchconditions,maturationalchangesoccurringduringtheperiodoflearningcanbeneglected.Suchrestrictions,however,eliminatethemostinterestingmaturationalproblems.

Sinceourexperimentwasdesignedprimarilytodetectdifferencesinproblem-solvingbehaviorattributabletoheredity,wedonothavedatatodemonstraterigorouslytheageatwhichvariouskindsoflearningbecomepossible.StudiesonmonkeysbyMasonandHarlow(1958a)andbyHarlow(1958)withthisobjectiveusedthesameproceduresbeginningatdifferentagesongeneticallysimilarsubjects.Severalstudiesfromourlaboratoryhavebeenconcernedwithlearninginnewbornpuppies(Fuller,Easier,andBanks,1950;Corn-wellandFuller,1960).Inordertoevaluatehereditaryfactors,however,itwasmorepracticaltogiveeachtestataparticularage.Toanextent,ourseriesoftestsrepresentstepsofincreasingdifficultycorrespondingtotheincreasedmaturityofoursubjects.Itwouldhavebeeninteresting,hadourresourcesbeenunlimited,tohaveinvestigatedboththegeneticandagevariables,sincesomeofthebreeddifferencesfoundmayhavebeensimplymanifestationsofdifferentratesofdevelopmentandwouldhavedisappearedifourtestshadbeencarriedoutatalaterage.Suchaninteractionbetweenrateofdevelopmentandheredityisprobablymoreimportantinyounganimalsthaninolderones.Wemust,however,rememberthatthereisapossibilityofsometransferofeffectfromone

however,rememberthatthereisapossibilityofsometransferofeffectfromonesituationtoanother.Conceivably,puppieswhofailedintheirfirsttestsbecauseofimmaturityalsodidpoorlyinlatertestsbecauseoflackofmotivation.Thus,far-reachingeffectsmightfollowfromsuchseeminglytrivialfactorsastheexactschedulingofthetests.

BARRIERORDETOURTEST

Thebarriertestwhichwasgivenat6weeksofagewasthefirstperformancetestforthepuppies.Itwasalsotheirfirstexperienceoutsidetheirownrearingroom,asidefromtheconfinementthattheyexperiencedinsmallcagesinthehallwhiletestswerebeingsetupinside.Consequentlywehadanopportunitytoexperimentwithatotallyunsophisticatedpuppy,andweattemptedtodevelopatestwhichwouldbesuitableforanimalsofthisageandatthesametimeshowuswhetherornottherewassomenativeproblem-solvingabilitywhichdidnotdependonpreviouslearning.

ThetestwasbasicallythesameasthedetourproblemdevisedbyKoehler(1927)foravarietyofanimals,anddetailsofpreliminarytraininghavealreadybeendescribedinchapter1.ThefirstrealproblemwaspresentedonDay3.Onthisdaythepuppyfoundabarrierbetweenhimandthedishoffood.ThisbarrierwasawoodenFrame,0feetlongand3feethigh,coveredwithpoultrywire,and

PROBLEM-SOLVINGBEHAVIOR

227

madeopaquewithheavypaperexceptforaslitonefootwideimmediatelyinfrontofthepuppy.Thusthepuppycouldseethefoodandtheexperimenter,butithadtomoveawayfromandoutofsightofthefoodinordertoreachthisreward.Theendsofthebarrierwereclearlymarkedbysupportswhichextendedoutonthepuppy'ssideofthebarrier.

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Fig.10.1.—Problemsinthebarriertest.Thistestwasperformedinanarena12X27feetinsize.Thebarrierwasopaque,exceptforawire-coveredopeningonefootwideimmediatelyinfrontofthegoal.Inordertoreachthegoal,thepuppyhadtomoveawayfromit.

Apuppycouldmakeaperfectscorebyrunningdirectlyaroundtheendofthebarriertothefooddish.Ifitstoppedorreverseditsdirectionanerrorwascounted.Inaddition,thetotaltimerequiredtoreachthefoodandthenumberofvocalizationsthatthepuppymadeineachminuteofthetestwererecorded.Ifthepuppydidnotgettothefoodwithin10minutes,theexperimentercalledthepuppyaroundtothefooddishandallowedittoeat.

Onthefourthdayofthetestthebarrierwasextendedoneitherendsothatitwasthreetimesaslongasonthefirstday.OnthefifthdaythebarrierswereconvertedintoaUshape,withonesideoftheUparalleltotheoriginalsideofthebarriersothatthegoalwasnowinadifferentlocation.Threetrialsweregivenoneachdayofthetest,andallpuppiesthushadanopportunitytolearnonesituationbeforeproceedingtothenext.

Itwasextremelyinterestingtowatchthepuppiesworkoutsolutionstothesesimpleproblems.Afewanimalsimmediatelyranaroundtheendofthebarrier,withoutmistakes.Othersranfirsttooneend,tookalook,thenreturnedtotheotherend,tookasecond

otherend,tookasecond

look,andthenrantothefood,usuallybackaroundtheendwheretheyfirststarted.Stillothersmovedonlyashortdistancefromthefood,whichwasofcourseinDiebehindthebarrier.Such

puppiessoonbegantorunbackandforthandtopawvigorouslybut:uallvonthewire,vocalizingastheydidso.Sometimesthiswouldgoonf:alminutes.Thenthepuppywouldstop,look

andrunaroundtheendtothefooddish.Vocalizationi^noffrustration,andnopuppiessolvedtheprob-whilevocalizing.

gdevelopedwithoutpreviousexperience:Anadultdogwouldimmediatelysolvesuchproblemsbvtakingonelookandrunningaroundthebarriertothefood.AsshowninTableI1.onlyavervfewpuppieswereabletodothis,someSoutofi3purebredpuppiestested.Ifthecapacityforsolvingadetourpreminfactbedevelopedwithoutexperience,thismusthave

occurredinonlyaverysmallproportionofpuppiesofanybreed.Ontheotherhand,ifthecapacityisdevelopedbvexperience,thereshouldbeamuchhigherpercentageofsuccessonthenextdaywhenorbutlongerbarrierispresented.Fourtimesasmanypuppiesmadeperfesonthefirsttrialofthesecondtestastheydidon

thefirst,andlargebreeddifferencesbegantoappear.Basenjisimprovedagreatdealmorethananyotherbreed,andbeaglesand1terriersweresecond.Thecockerspanielsandsheltiesshowednoimprovement.Thesediffere:emtoresultfrom

ditjnstofrustratingsituations.Basenjisatthisageare

usuallyhighlyactiveandwelldevelopedphysically,whilethepuppiesofmostotherbreedsarestillfatandclumsy.Inmar.thecodhfailedwouldsimplyliedownandgoto

sleepuntilthetestperiodwasover.ThebasenjisremainedactiveandEthusmorelikelvtosolvetheproblembvchar.

puppic_-.bletosolvethethirdproblem

apedbarrier|withouterrors.Eventhenumberofsuccessfulnsiderablvreduced.Thisindicatesthatpuppiesofthiselimitedcap.,aralization.Inoneofthepre-

liminaryexperiments,thestraightbar:simplyrotated1S0:in

thesameroom,andthepupp:edtothisasifitwereanen-

-ituatio:thedifl.Dnbetweenthebreeds

rer:Ecuterriersandbeaglesr.

andcockersandsheltiiL

.usionscon.g:helackofgeneralizationareborne

outbythecorrelationsbetweentlhenall

breedsandhybridsareconsidered,performancesonthelongand


229

TABLE10.1

NumberofAnimalswithExcellentPerformanceontheDetourTest—FirstTrialsOnly

Breed

Xt'MBER

Tested

XiuberofErrors

0■

Total

PerCent

shortbarriersarecorrelatedat.16,butthecorrelationbetweenperformancesonthelongbarrierandtheU-shapedbarrierisonly.07.Correlationswithinthepurebreedsandhybridsarehighlyvariable.ThebehaviorofthepuppiesindicatedthateasilylearningProblem1mightactuallybeahandicapindealingwithProblem2,becausethepuppymightturntoosoonwhenrunningaroundthelongbarrierandthusbecomeconfused,whereasananimalwhichhadmadeseveralmistakeswouldhaveexploredtheapparatusmorethoroughlyandthusrecognizechangesmorequickly.

MANIPULATIONTEST

Asweworkedwiththebasenjisweobservedthattheywereconsiderablymoreskillfulwiththeirpawsthantheotherbreeds,sometimesusingtheminanalmostcatlikefashion.Themanipulationtest

wasdesignedtomeasurethisdifferenceobjectively.Thepuppieshadbeenpreviouslytrainedtoruntoawoodenboxcontainingafooddish(seegoal-orientationtest,chap.9).Duringthefollowingweektheywereconfrontedwiththeproblemofremovingthedishfromthebox,whichwasnowcovered.

Onthefirstproblem,thetopoftheboxwascoveredwithhardwareclothsothatthepuppiescouldseeandsmellthefood,butcouldreachitonlvbvpullingornosingthedishoutthroughtheopensideofthebox.Onthefirsttrial,thedishprotrudedenoughsothatthepuppycouldeasilygetthefoodbystickingitsnoseintothetopofthedishandforcingitoutward.Verynearly100percentoftheanimalswereabletodothis.Thispreliminarytrainingwasrepeatedoneachdavofthetestsothatthepuppieswouldberewardedbysuccessandfoodatleastonceperday.

Ontheseconddav.thepuppvwentthroughthefirsttrialasbefore,butonthesecondtrialfoundthedishfartherbackinthebox,makingitmoredifficulttopullout.Onthethirdday,thedishwasstillfartherbackbutwasattachedtoasmallwoodendowelandastring,sothatthedishcouldbepulledoutwiththestring.Theanimalcouldalsopawitoutdirectly,butthiswasquitedifficulttodo.Thetestonthefourthdaywassimilartothatonthethird,exceptthatthedishwasstillfartherbackinthebox,makingitalmostimpossibletopulloutthedishexceptwiththestring.Finally,onthefifthdaythewholeproblemwaschanged.Thistimetheboxhadnobottom,anditsoneopensidewasagainstthewallsothatthepuppieshadtopulltheboxoffthedishratherthanpullingthedishoutofthebox.

dishoutofthebox.

Therewereavervlargenumberoffailures,sothatthetestisbestanalyzedintermsofproportionsofsuccessesratherthaninthoseoftimerequiredtosolvetheproblems.

AglanceatFigure10.2indicatesthattheperformanceofthebreedswasgenerallvconsistentonallpartsofthetest.Basenjisalwaysdidthebestandcockerspanielstheworst.Beagles,wire-hairedterriers,andsheltieswereintermediate,theirrelativeranksfluctuatingsomewhat.Thechiefeffectofthedifferentformsoftheproblemapparatuswasthatthepresenceofthestringmadethesolutioneasierforallbreeds.

Oneofthemostinterestingobservationswastheeffectofrepeatedfailureuponthebehaviorofanyparticularanimal.Onthefirstfailureitwouldpersistentlytryavarietyofwavstogetatthefood,scratching,nosing,andevendraggingtheheavyboxaround.Onthesecondtrialitwouldmakeamuchbrieferattempt,andbythethird


231

orfourththepuppywouldusuallygouptothebox,takeonelook,andthenreturntothegatetowaitouttheremainderofthetwominutesallottedtothetrial.Thustheanimalveryquicklyformedhabitswhicheffectivelypreventedanyfuturesuccess.Thispointsuptheimportanceofsuccessinenhancingmotivation.Theresultsare,ofcourse,consistentwiththeknowneffectsofreinforcementonthemaintenanceorextinctionofconditionedresponses.

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Fig.10.2.Resultsofmanipulationtestonsuccessivedays.Notethatbasen-jisareconsistentlythebest,cockerstheworst.

Thesignificanceofthisphenomenoninrelationtotheeffectofheredityuponbehavioristhatitdemonstratestheimportanceofmaintaininghighmotivationinordertobringoutthemaximumgeneticcapacitiesoftheindividual.Ifananimalissubjectedtoaproblemevenslightlybeyonditspowersattheoutset,itmaysimplylearntoinhibitapproachandmanipulativebehaviorwhichhasnotbeenreinforced.Aslightlylessdifficultproblemattheoutsetoftrainingcouldmakethesameanimalintoahighlypersistentindividual.Weobservedthatapuppywhichhadconsistentlysucceededinthistestforseveraltrialswouldrespondtoadifficultproblemwithanalmostdesperateeffort,andwouldstillbeattackingtheboxattheendofthe2-minuteperiod.

Becausethereweresomanyfailures,wecontinuedthetestinan

232BREEDDIFFERENCES

attempttofindoutwhetherdogscouldlearnbyfollowingahumanexample.Theanimalswhichfailedweredividedintotwogroups,experimentalsandcontrols.Withtheexperimentalsthehandlerattemptedtoshowthepuppythesolutionbyscratchingontheboxwithhisfingerandmovingit.Manypuppiesbecameveryexcited,andsometimesjoinedinthescratching.However,therewaslittleevidencethatthepuppieslearnedtoperformthetaskindependently.Somepuppiescouldprobablybetaughtinthiswaywithconsiderabletimeandpatience,butthemethoddoesnotworkefficiently.

AMAZETESTFORDOGS

Bytheageof13weekspuppieshavealargerepertoryofresponsesandcanlearnspatialrelationshipswithconsiderablespeed.Atthisagetheywereintroducedtoa2-weektestingperiodona6-unitmaze.Thepatternofrightandleftturnsinthismazecouldbereadilyreversed.Halfthepuppiesfromeach

leftturnsinthismazecouldbereadilyreversed.HalfthepuppiesfromeachlitterweretestedwiththearrangementRLLRRRandtheotherhalfonLRRLLL(Fig.10.3),thepuppiesbeingalternatedsothatanyscentcuesfromthepreviousanimalwouldbeconfusing.

Themazewasconstructedofwoodenframescoveredwithpoultrymeshinanattempttosimulateapathwaythroughadensethicket.Previousexperimentswithenclosedmazeshadnotworkedwellbecauseofthepuppies'apparentdistresswhenconfinedwithinopaquebarriers.

OntheMondayclosesttoits13-weekbirthday,thelitterwasbroughttoaholdingcageoutsidethetestingroom.Eachpuppyinturnwasplacedinthefinalsectionofthemazeandallowedtoemergeandeatasmallportionoffoodwhiletheexperimenterstoodby.TheprocedurewasrepeatedonTuesdayinordertohabituatethesubjectstothetestsituationandtobuilduptheirmotivationtoreachthegoalbyrepeatedreinforcement.Judgingfromtheirbehavior,thepuppiesweremotivatednotonlybythefoodbutalsobyescapefromarestrictingspaceandbytheopportunitytocomeincontactwiththeexperimenter.Asecondperson,theobserver,satonaraisedplatformbehindascreenandrecordedthesubject'sresponses.

MazerunscommencedonWednesday.Theexperimenterplacedthepuppyintheinitialsection,thenwalkedrapidlyaroundtheoutsideofthemazeonthesidewiththemostblindalleys.Experimentersweredirectednottoattracttheattentionofthesubjectsor


toprovideanycuestothecorrectpathatthesuccessivechoicepoints.

Recordsweremadeofthetimeinsecondsrequiredtorunthemazeandofthenumberoferrors,definedeitherasreversalsorcompletestops.Eacherrorwasrecordedonaplanofthemazeas

FINISH

Fig.10.3.—Floorplanofthemazetest,left-handpattern.Externalprojectionsresultedfromtheuseof6-footsectionsinerectingthemazeandhadnoeffectontheperformanceofthepups.

aconsecutivenumber,sothatalinedrawnbetweenthemwouldgiveacomplete

aconsecutivenumber,sothatalinedrawnbetweenthemwouldgiveacompleterecordoftheanimal'smovementsthroughthemaze.Theaveragerunningtimeanderrorscores(excludingDay1)weretakenastheprincipalmeasuresofindividualperformance.However,thesecompositescoresgaveaninadequatepictureofperform-

234BREEDDIFFERENCES

anceonthemaze.Forexample,ananimalwhichlearnedthemazegraduallyandslowlywouldreceiveapproximatelythesameaverageerrorscoreasonewhichmadealargenumberoferrorsatfirstandthenmadeaquickreductionandranconsistentlythereafter.Also,onthebasisofotherperformancetests,weexpectedthattheprincipalgeneticdifferenceswouldshowupinthewaysinwhichtheanimalssolvedtheproblemratherthantheendresult.Wethereforescoredthetestsinmanyways.

Asitturnedoutsixofthese,inadditiontotheaveragetimeanderrorscores,showedimportantbreeddifferences.Thesewere:(1)minimumtime;(2)minimumerrors;(3)rangeoftime(probablyreflectingminimumtime);(4)rangeoferrors(relatedtominimumerrors);(5)thespeedscoreonthefirstday;andfinally(6)thehabitscore,whichreflectedthetendencyoftheanimaltoformastereotypedpatternofrunningthroughthemazeduringthelatterpartofthetest.Inaddition,duringthefirsttwodaysofpreliminarytraining,theobservergavethesubjectsaconfidenceratingbasedonbodypostureandtailcarriagejustafterthepuppiesfoundthemselvesinthemaze.Thisgaveanopportunitytomeasurethepossibleeffectsofemotionalresponsesonmazeperformance.

Whenfirstintroducedintothemaze,apuppyusuallyattemptedtofollowtheexperimenter,thenstoodforamomentbythewiremesh,andfinallybegantorunaroundrapidlyinsidetheapparatus,apparentlysearchingforawayout.Ifhewasnotimmediatelysuccessful,hemightbecomeemotionallydistressedandbegintoyelp.Aswithpuppiesonthefirstbarriertest,behaviorbecamequitestereotypedatthispoint,thepuppyrunningbackandforthandpawingatthebarriers.Foxterrierssometimestriedtobitetheirwayout.Finallythepuppywouldworkitswaythroughthemaze,eatthefish,andbecarriedbacktoitslittermates.

Onsubsequentdays,performanceimprovedrapidly.Afewsubjectsafter4or5trialswereabletosolvethemazevisuallybyobservingthepathaheadthroughthetransparentwalls.Butcareful,slow,errorlessprogressionthroughthe

thetransparentwalls.Butcareful,slow,errorlessprogressionthroughtheapparatusneverpersisted,becausetheseanimals,likeotherswhichneverdevelopedavisualsolutionatall,soonadoptedastereotypedhabitofalternatingrightandleftturns,thusmakingtwoerrorsoneachtrial.Afewindividualsformedthehabitofalwaysturningtoonesideeventhoughthismightinvolveentering4blindalleyspertrial.

AverageerrorsandtimesforthefivepurebreedsareshowninFigures10.4and10.5.Thetwofamiliesofcurvesareverysimilar,anddifferencesbetweenbreedsaremanifest,particularlyduring


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BREEDDIFFERENCES

thefirstdays.ElliotandScott(1963)performedacomplexanalysisofcovarianceonthisexperiment,takingintoaccountthepossibleeffectsofbackgroundconditionssuchasconditionsoftestingandrearing.Inthisdetailedanalysisofthedata,thevarianceassociatedwithbreeds,matings,litters,andindividualswascalculatedforeachscore.Inaddition,theproportionsofvariancerelatedtoenvironmental,error,andbackgroundfactorswerecalculated.Theseincludedroomtemperature,ageofmother,orderoflitter,littersize,sexoflittermates,sex,bodysize,andemotionalfactors(measuredbvtheconfidencerating).

TABLE10.2

PercentageofTotalVarianceofMazeScoresRelatedtoBreed,Mating,Litter,andBackgroundVariables

MinimumTime

MinimumErrors

Range

Time

RangeErron

Habit

jpeed

Sumofsquares

Breeds:

Total

Residual

Habit*

Background

Matings

Litters

Individual:

Habit*12

Background8

Sumofexplainedvariance55

Remainingunexplained

individualvariance45

7

9

56

44

4

3

49

51

3

3

48

52

517

99

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118

6

34

66

458

3810

4

2411

9

6

771

29

Portionsofbreedandindividualvariancerelatedtohabitscore.

Whenthebackgroundvariancewassubtracted,therewerenosignificantbreeddifferencesintheaverageerrorandtimescores,confirmingouroriginalimpressionthattheseareinadequatemeasuresofperformance.Significantbreeddifferencesremained,however,intheminimumtimeandminimumerrorscoresandinthespeedscoreonthefirstday—theremainingvarianceduetobreedrangingfrom11to15percentofthetotal.Significantdifferencesalsoremainedintherangeoferrorsandrangeoftimesconwellasthehabitscore,forming7to9percentofthetotal(Table10.2).Incontrast,thetotalvarianceduetobreeds,includingthatassociatedwithbackgroundfactors,wasintheneighborhoodof20percentformostofthese6measuresofperformance,althoughthatofthehabitformationscorewasonlv9percent,duetothefactthatalmostallthedifferenceswerecausedbyonebreed,thebeagle.


Thehighestproportionofexplainedvariance,71percent,wasobtainedwiththespeedscore,whichisbasedonthefirstday'sperformance.Theothervariables(compoundedfromseveraldays'scores)standatapproximately50percent.Thedifferenceisaccountedforbythelargeeffectofbackgroundfactors(24percentofthetotalvariance)associatedwithbreedonthespeedscore.Wecanconcludethatbackgroundfactorsassociatedwithbreed,suchaslittersize,orderoflitter,ageofmother,waistcircumference,confidence,andtemperature,havetheirmaximumeffectonthefirstday'sperformance.Thissuggeststhatsuchfactorsmighthaveanimportanteffectonsuccessmotivationintestsinwhichinitialfailureswerepermitted,suchasthemanipulativetest.

Inmostofthemeasures,thereisabout50percentofunexplainedindividualvariance,presumablycausedbyindividualgeneticfactorsandunmeasuredenvironmentalfactors,suchaspreviousexperienceandrandomdistractions.To

environmentalfactors,suchaspreviousexperienceandrandomdistractions.Totaketheminimumtimescoreasanexample,aboutone-fifthofthetotalvariance(19percent)isassociatedwithbreeddifferences.Ofthis,aboutone-fifthiscausedbymiscellaneousbackgroundvariablespeculiartothebreeds—sex,sizeoflitter,andorderoflitter.Differencesbetweenmatingswithinabreed,whicharealsopresumablygeneticinorigin,accountfor12percentofthetotalvariance.Excludingthevarianceassociatedwiththehabitscore,thevariancewhichcanbedefinitelyassignedtogeneticfactorsis21percent,plusanunknownamountofindividualgeneticvariancewithinthebreeds.

Fromthesedataonecancharacterizethebreedsinthefollowingways,rememberingthatconsiderableoverlapexists.FoxterriersandShetlandsheepdogsmakemoreerrorsandconsequentlyshowlongertimesthantheotherthreebreeds.OnthefourmeasuressummarizedinFigure10.6,beaglesappeargenerallysuperiorandShetlandsheepdogsinferior,withtheotherthreeintermediate.Thesuccessofbeaglesisattributedtotheiravoidanceofstereotypedhabitsandcharacteristicrapidrandominvestigationoftheirsurroundings.Althoughtheyoftenresultinpoorinitialperformance,theseformsofbehaviorcontributetorapidsolutionofthemaze.TheShetlandsheepdogsappearedtimidandhesitantinthemazeanddevelopedstrongstereotypedhabits.Theothernotablefeatureofthedataisthegoodperformanceofbasenjisonthefirstday.Basenjisappearmoreobservantandlessexcitedthantheotherbreeds,asifmakingmoreuseofvisualcues.

Thusheredityseemstoaffectperformanceinthistestlargelybydeterminingemotionalreactionsaffectingconfidenceandthechoice

BREEDDIFFERENCES

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ofbehaviorpatterns.Theactualorganizingprocessesinthecentralnervoussystemseemtobelittleaffected,exceptinthecaseofthetendencyinallbreedsexceptthebeagletoformstereotypedhabitsrapidly.

CUERESPONSEANDDELAYEDRESPONSE

Eachofoursubjects,beginningat22weeksofage,wasgivenaseriesofthreerelatedtestsinaT-mazeinordertodiscoverwhateffectgeneticdifferencesmighthaveonthisformofproblemsolving.Animportantpartofsolvinganyproblemistheassociationofparticularcueswithappropriateresponses,orlearningtodiscriminate.LearningtogooncuetoonearmortheotherofaT-mazetoreceiveafoodrewardisrepresentativeofthisbasicclassofproblems.

TheapparatusisshowninFigure10.7.Subjectswererestrainedinthestartingbox,whichhadameshdoorandpermittedaclearviewoftherunwayandthediscriminativecues.Thesewere12X30-inchhingedpanels,eachpaintedblackwitha3-inchwhitestripedownthemiddleandmountedattheentrancestotheescapecor-



ridoroneachside.Bypullingcords,theexperimentercouldmoveonepanelortheotherthroughanarcofabout30°.Movement,ratherthanlevelofilluminationorpattern,waschosenasthediscriminativestimulusbecausedogsattendreadilytomotion,anditwashopedthatlearningwouldbemorerapidthanwithconventionalstationarystimuli.Themovingpanelalsomadesomenoisewhichservedtoattracttheattentionofthesubjects.

Fig.10.7.—T-mazeusedforcue-response,discrimination,anddelayed-responsetests.

Abarrierextendingdownthemiddleoftherunwayforcedsubjectstochooseasidebeforetheycouldseewhichofthecorridorswasopen.Thebarrierwashingedsothataportioncouldbeswungtoeitherside,thusblockingoneoftheexitcorridorsandforcingtheanimaltogototheoppositeside.Equalnumbersofforcedtrialstobothsideswereusedasatrainingprocedureforthreedaysbeforediscriminationtestingwasbegun.Forcedtrialswereinterposedunderspecifiedrulesintothediscrimination-learningserieswhenspatialpreferencesseemedtobeinterferingwithlearning.Inordinarytesttrials,retracingandcorrectionoferrorswaspermitted.

Afteremergingfromtheapparatus,dogscouldruntothevicinityofthestartingboxandreceivefood.Somedogs,includingsomewhichlearnedreadily,seldomateinthetestsituation.Escapefrom

BREEDDIFFERENCES

themazeenclosureandhandlingbytheexperimenterwereapparentlysufficientinsomeinstancestomotivateacquisitionofadiscriminatedresponse.

Preliminarytraining(motivationtest).—Thethreedaysofpreliminarytrialsservedadualpurpose,habituationtotheapparatuspreparatorytodiscriminationtrainingandatestofmotivationaldifferencesbetweenbreedsandhybrids.Oneachofthreeconsecutivedays,thesubjectsweregiven10forcedtrialsintheorderofRLRRLRLLRL.Themovingcuewaspresentedoneachtrial;timewastakenfromtheopeningofthestartinggatetoemergencefromtheapparatus.Theresultsofthistestwereusedinchapter7toillustratethemethodofcomputingstaninescores.Forcertainpurposes,wehavealsochosentopresentresultsasspeedscoresobtainedbymultiplyingby1,000thereciprocalofthetotaltimeinsecondsfor10trials.

TheaveragestaninescoresforthethreedaysaresetforthforeachbreedinFigure10.8.Allbreedsshowday-by-dayimprovement,andthefivepurebreedsformtwodefiniteclusters:beagles,foxterriers,andspanielsrunfasterthanbasenjisandShetlandsheepdogs.

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241

Cueresponse(discrimination).—Onthedayfollowingcompletionofthemotivationtest,testingforadiscriminatedresponsewasbegun.Eachsubjectwasgiven16trialsperdaywiththebarrierinacentralpositiontoallowrunningtoeitherside.Twoseriesoftrialsweregiven:thefirstterminatedeitherwhenacriterionoflearningwasattainedorafter128trials;thesecond,givenonlytosubjectswhichmetthecriterion,consistedof50additionaltrials.InordertoequalizeinsofaraspossiblethelevelsofperformanceattheendofSeriesI,threeindependentlysufficientcriteriaweresetupforitstermination.Arunofconsecutivecorrectresponses,computedaccordingtothetablesofGrant(1947),wastheusualbasisfora"pass."Inthissystem,thelengthofthecriterion-runincreasesastotaltrialsaccumulate.Asecondcriterionwas14correctoutofthe16trialsononeday.Finally,attheendofthe128trials(theupperlimit),atotalof79ormorecorrectresponsesovertheserieswassufficienttoindicatebetterthanchanceperformanceatthe1percentlevelofsignificance.The50additionaltrialsgiventosubjectswhichmetthecriterionmeasuredconsistencyofresponseandprovidedsomeoverlearningaspreparationforthede-laved-responsetestwhichfollowed.

Performanceonthecue-responsetestcanbemeasuredinseveralways.InTable10.3aredataontheattainmentofthecriterionbythefivepurebreeds.

TABLE10.3AttainmentofCriterioninCue-ResponseTest

Thevalueofthechisquareforcomparinganimalsmeetingthecriterionbeforetrial64withallothersis22.686with8degreesoffreedomandP<.01.Becauseofthesmallexpectednumbersinsomecells,comparisonsbetweenbreedsaresomewhatrisky;butitissafetoconcludethatourstrainofShetlandsheepdogswasnotasgoodindiscriminationaseitherwire-hairedterriersorbeagles.

Onedifficultywiththetechniqueoftrainingtoacriterionisthat

242BREEDDIFFERENCES

somesubjectsdidnotlearntheproblemduringthelimitednumberoftrialswhichcouldbeallowedforanyoneprocedure.Inretrospect,webelievethatmanyofthefailureswouldhavemetthecriterioniftraininghadbeencontinuedfortwoadditionaldays(160trialstotal),buttherulescouldnotbechangedinthemiddleoftheexperiment.

Thetotalnumberofcorrectresponsesisanothermeasureofperformancewhichhascertainadvantagesbecauseeveryindividual,includingfailures,receivesadeterminatescore.Undertherulesofprocedureadopted,itwaspossibleforasubjecttocompletethetestinfourdaysbymeetingthecriteriononthefirstdayandreceiving50confirmatorytrialsonthefollowingthreedays.Sincesomesubjectsweretestedonlyfortheminimumof64trials,wehavecalculatedtheresultsintermsofcorrectresponsesoutof64.Afewanimalsacquiredthediscriminatoryresponseduringthepreliminarytrainingwithforcedrunsandobtained60ormorecorrectresponsesoverthefourdays.Others,particularlyamongthebasenjisandShetlandsheepdogs,werestillperformingatachancelevelafterfourdays.Onlystaninescoresof7orbetterindicatesignificantlearning,butscoresinthemiddlerangemayrepresentanimalsonthewaytomeetthecriterion.

Meanstaninescoresforcorrectresponsesoverthefirstfourdaysofcue-responsetrainingwere:wire-hairedterriers5.95;beagles,5.75;cockerspaniels,4.58;Shetlandsheepdogs,4.42;andbasenjis,4.39.Nonedeviatefarfromthemean,andtheoveralldifferencesbetweenbreedswerenotsignificant.Amongspaniels,sheepdogs,andbeagles,however,individuallittersdeviatedsignificantlyfromthebreedmeans.Whetherthiswascausedbycommonexperientialfactorsorbycharacteristicsofaparticularmatingisnotknown.

Delayedresponse.—Subjectswhichmetthecriterionforcueresponsewere

Delayedresponse.—Subjectswhichmetthecriterionforcueresponseweretestedinthesameapparatusondelayedresponse.Forthisprocedure,theappropriatepanelwasmoved,acurtainwasthendroppedoverthedooroftherestrainingcage,andthedoorraisedfollowingaspecifiedintervaloftime,afterallpanelmotionhadceased.Thesubjectwas,bvthisprocedure,forcedtorespondintheabsenceofthediscriminativestimulus.Thedelayed-responsetest,originatedbyHunter(1913),hasbeenwidelyusedtoassesstheresultsofbrainlesions,particularlyinthefrontalregions,andwewereinterestedinpossibledetectionofhereditarydifferencesinbrainfunction.

Obviously,therearemanydifficultiesinageneticexperimentinapplyinganytestwhichdependsuponpriortraining,andespecially


243

whensubjectsareeliminatedbylackofsuccessinpreliminarytraining.Norealmeasureofdelayedresponsecouldbeobtainedfromsubjectswhichdidnotmeetthelearningcriteriaofthecue-responsetest.Yetwecannotconcludethatthesenon-learnersweredeficientinattributesmeasuredbydelayedresponse,forthegroupofanimalsreceivingdelayed-responsetrainingwasabiasedsampleofourtotalgroup.Hence,itisimpossible,onthebasisofourexperiment,tocometodefiniteconclusionsregardingthedistributionofdelaved-responseabilityamongdogbreeds.However,thedataarestillofinterestbecauseofthegreatamountofindividualvariationshown.

TABLE10.4Delayed-ResponsePerformanceofFivePureBreeds

Thedelayed-responsetestwasdesignedasa"power-test"toprobetheupperlimitofeachdog'sability.Thus,themeasureadoptedwasthemaximumlengthofdelayinsecondspermittingacorrectresponseintheT-mazeundertheproceduredescribed.Delayintervalswere1,5,10,15,30,60,120,and240seconds.Amaximumof40trialswasallowedtomeetthecriterionat1-seconddelay;30trialswasthelimitforlongerdelays.Oncealevelwasfailed,testingwasdiscontinued.AsummaryoftheresultsofthistestisshowninTable10.4.Itisapparentthattherangeinanyonebreedisgreat.Amongthecockerspaniels,oneindividualpassedthetestatadelayof240seconds,anintervalwhichplacedastrainonthememoryoftheexperimenters,but32percentwereconfusedbythebriefestpossibledelay.TheShetlandsheepdogshadthepoorestrecord,but

thebriefestpossibledelay.TheShetlandsheepdogshadthepoorestrecord,butsofewweretestedthatitisnotlegitimatetoconsiderthemasanadequatesampleofthebreed.Infact,noover-alldifferencesbetweenthebreedscanbedemonstratedbythechi-squaremethod.Oncetheoriginalhurdleoflearningthediscriminationissur-

244BREEDDIFFERENCES

mounted,theprobabilityofsuccessondelayisaboutequalforallbreeds.Itisnotequalforalldogs.Over28percentfailtomeetcriterionontheshortestdelay,andabout32percentareabletomeetonlythisrequirement,failingonlongertrials.About40percentcandelay5secondsormore,whileanoccasional"genius"reaches60,oreven240seconds.Partofthesuccessisduetotheholdingofafixedattitudeduringthedelay.Theanimalaimsitselfwhenthestimulusispresentedandpullsthetriggerlater.Thisisnotthewholestory,however.Somesubjectswithsuccessatlongdelaysactuallycircledintherestrainingcageduringthedelay,andmanymovedtheirheadsfromsidetosideorpawedatthestartinggate.Thepointofthisexperimentisthatapower-testcanuncovergreaterindividualdifferenceswithinaspeciesthandoesatestoflearningwhichiswithintheabilityofallsubjects.Otherexperimentsinourlaboratoryhaveshownthatevenprolongedpracticedoesnotappreciablyincreasethemaximumdelayed-responsetimeofadog.Understabletestingconditions,ananimal'slimitfluctuateswithinarelativelynarrowrange,perhapsbetween15and20secondsorbetween20and30seconds.Butthistestwithitsdemonstratedabilitytodetectindividualvariationfailedtodemonstratebreeddifferences.Thusthehereditarydeterminationofdelayed-responseabilityisneitherprovednordisproved.Aselectionexperimenttodeterminetheheritabilityofthecharactermightyieldimportantresults.

THETRAILINGTEST

Thistestwasdevelopedinanefforttostudyvariationsinthetrackingbehaviorthatissocharacteristicofdogs.Thedifficultiesofstandardizinganoutdoortestatdifferenttimesoftheyearandundervaryingweatherconditionsweresogreatthatwedevelopedacompletelyartificialindoortest.

Thereisnodoubtthatbreedsdifferintheircapacitiestofindpreyundernaturalconditions.Preliminaryexperimentswithbeaglesinanoutdoorsituationindicatedthatifananimalhadfoundanobjectinaparticularplace,onthesecondtrialitwentdirectlytotheoriginalplaceandstartedsearchingfromthere.Wesetupourexperimentalapparatustotakeadvantageofthisfact.

there.Wesetupourexperimentalapparatustotakeadvantageofthisfact.

Thenextproblemwastosetupsomesortofartificialtrailwhichcouldbeexactlyduplicatedintestaftertest.Wetooksome1-inchboards,10feetlongand2incheswide,andattachedaluminumplatestothemat1-footintervals.Wethenlaidatrailalongthe


metalplatesbvplacingadropoffishjuiceinthecenterofeachwiththeendofaf-inchwoolendowel,beginningatthepointwherediedogwastobestarted.AspoonfuloffishinasmallSyracusewatchglasswasplacedatthefarendoftheboard.

Thenextstepwastotraintheanimalstoassociatetheartificialtrailwithfindingareward.Onthefirstdayanexperimenterledthedogthatwastobetestedovertheentireloftinwhichthetestwastobegivenandlethimeatatthefuturestartingpointofthetrail.Theideaherewastolettheanimalbecomereacquaintedwiththeroom,whichwasthesameoneinwhichithadbeenpreviouslytestedonthedetourandmazetests.

Onthesecondtrial,atrail20feetlongwaslaidout,startingfromthepointwheretheanimalhadbeenfedthedaybefore.Wefoundthatmanydogsstartedoffinthewrongdirectionand,inordertomakesurethattheyobservedthetrail,wesurroundedthestartingpointwithaU-shapedfencewhichforcedthemtomoveintherightdirection.Nevertheless,manyanimalsfailedtofindfoodwithinthetimelimit.Iftheydidnotsucceed,theywereplacedonaleash,leadtothefish,andallowedtoeat.Thisprocedurewasrepeatedonceonthefirstday.Onthefollowingday,2trialsweregivenwithouttheU-shapedfence.Onthese4trialsthedoghadtheopportunitytoassociatethescentedboardwiththerewardoffishatitsend.Manyanimalswouldrunalongtheboardwiththeirnosesdirectlyoverthedropsoffishjuice.

Thenextdaywebegantestsontrackselection.Twobrancheswereaddedontheendofthetrail,ascentedonewhichledtothefishandanother,unscented,whichledtoanemptydish.Ifthedoghadassociatedthesightofthetrailwiththefoodreward,hemightaseasilytakeonebranchastheother.MostofthedogsrantotheforkoftheVandbegansearchingfromthere.Thenextpartofthetestwasmoredifficult.AsecondVwasaddedatthelastpointwherethefishhadbeenfound,butthistimethebranchontheoppositesidefromthefirstheldthereward.

thereward.

OnthefinaldayasimpleY-shapedapparatuswassetupinadifferentpartoftheroomandthedogsgiventrialswiththerewardfirstononesideandthenontheother,totestwhetherthedogscouldgeneralizetoanewlocation.Inall,therewere3trialswithasinglechoicepointandonewithadoublechoice.

Thewholetestwassetupsothattheonlyreliablecuetothelocationoftherewardwasthescenttrail.However,thedogscouldanddiduseavarietyofmethodsforsolvingtheproblem.Theycould,forexample,learnthattherewardwasalwaysattheend

BREEDDIFFERENCES

ofoneofthetrailsandgofirsttotheendsandcheckthese.Asecondtypeofvisualsolutionconsistedoflookingaroundtheroomastheyranoverit,payingnoattentiontothetrail.Thebeaglesusuallyemployedstillathirdmethod,circlingrapidlyaroundtheroomuntiltheyapparentlydetectedanairbornescent.Thentheydroppedtheirnosestothegroundandinvestigatedthefloorinchbyinchuntiltheylocatedthefish.

Theresultsindicatedthattheproblemaspresentedbyuswaslearnedbyfewdogsduringthebriefperiodoftraining.AsTable10.5shows,only7dogsoutof143solvedthelastproblemperfectly

TABLE10.5

AnimalsShowingPerfectPerformanceontheFinalTrialoftheTrailingTest

byfollowingdirectlyalongthefish-scentedtrail.Theseanimalsweredistributedthroughoutallthebreedsexceptthefoxterriers.Failuretofollowthetrailclosely,however,mustnotbeconfusedwithfailuretosolvetheproblembyoneofthealternativemethods;27subjectshadnofailuresonanytrials.

Onesurprisingresultwasthatthecockersandsheltiesdidaswellasthebeaglesonthetest(seeTable10.6).Terriersandbasenjis

TABLE10.6

RelativeRanksofBreedsonPerformanceonMostDifficultTrialofTrailingTest(Trial7)

AverageTime(sec),SuccessfulAnimals

1.Beagle51.4

2.Cocker53.9

3.Sheltie54.6

4.Basenji74.5

5.Foxterrier77.8

PerCentofSuccesses

1.Sheltie56

2.Cocker53

3.Beagle50

4.Foxterrier30

5.Basenji23

didlesswell,anditsoonbecameapparentthatthepoorperformanceofthebasenjiswascausedchieflybytimidity.

Astheexperimentwenton,weobservedthatsomeanimalswere


247

apparentlyfailingthetestbecauseoffearoftheartificialtrailitself.TheyrefusedtocrossthearmsoftheYinordertogettothefood;andwhenledtothegoal,theyvigorouslyresistedbeingforcedtocrosstheboardtrack.Inthemostextremecasesthedogsnevercrossedthearmsofthetrailin4consecutivetrials.Weusedthisbehaviorasameasureoftimidity.

AsshowninTable10.7therearemanymorecasesoffearreac-

TABLE10.7DistributionofFearReactionsinTrailingTest

TABLE10.7DistributionofFearReactionsinTrailingTest

tioninbasenjisthanincockerspaniels.Ifthebasenjiswhichfailedbecauseoffearreactionareexcludedfromthesummary,verylittledifferenceremainsbetweenthetwobreeds.Therefore,thefearreactiontotheapparatusaccountsformostofthedifferencebetweenthescoresofthecockerspanielsandbasenjis.

Fearofapparatusisnottheonlyfactorproducingbreeddifferencesinperformance,sincethefoxterriers,whichmakefewtimidityresponses,werealsopoorinthetrailingtest.However,resultswithothertestsinwhichstrangeapparatuswasusedindicatethatfearwasfrequentlyacomplication.Evenafterextensivehabituation,somesubjectsavoidedapparatusandwereexcessivelydistractedbysightsandsoundsinthetestspace.Thismatterisdiscussedfurtherinchapter14.

THESPATIAL-ORIENTATIONTEST

Theseriesofproblem-solvingtestswasclimaxedbyaprocedurewhichwenamedthespatial-orientationtest.Fundamentally,theapparatusconsistedofanelevatedgoaltableonwhichfoodwasplaced.Accesstothefoodwaspossibleonanyonetrialbyonlyonesetofthreerampsleadingupfromtheground.Theconstructionwassuchthatanimmediatevisualsolutionwaspossibleifthe

BREEDDIFFERENCES

subjectsutilizedvisualcues.Itisoftenstatedthatsomebreedsareguidedpredominantlybysight,othersbyolfaction;andtheapparatusdesignwasintendedtodetectsuchdifferences.Inordertominimizedisturbanceproducedbyunfamiliarobjectsandplaces,theequipmentwassetupineachhomepenonedaypriortotraining.

Anobjectiveofthetest,inadditiontoclarificationofhypothesizeddifferencesinutilizationofvisualcues,wastherelationshipbetweenmotivationalfactorsandsuccessinreducingerrors.Measuresofrunningspeedduringthetestandofthepersistenceofapproachbehaviorfollowingcompleteblockingoffofthefoodwereincludedforthispurpose.

Testdesign.—ThearrangementoftheequipmentisshowninFigure10.9.Thisapparatus,constructedofheavywood,wasset

Fig.10.9.—Apparatususedinthespatial-orientationtest.

upforeachlitterinitsregularlivingspace.Thegoalcagewasawoodenframecoveredonthreesidesbvheavybrowncanvasoverawiremesh.Inalatermodel,plywoodsideswereused.Wingsextendedlaterallyonbothsidesoftheentranceandpreventeddogsfromedgingaroundthetableintothecage.Theyalsoservedtoemphasizethepositionoftheopenside.Thecagewasrotatedonthegoaltablesothatonepathwaywasopenatatime.Thegoaltablewas36incheshighand30inchessquareontop.Theinter-


mediatetableswere28incheshigh.Rampswere5feetlongand20incheswide.Thefreespanofthe18-inchbridgeswasabout5feet.Justprevioustotesting,allmembersofalitterwereremovedtosmallretainingcagesoutsidethelivingquarters.AnimalswereintroducedintothetestareaoneatatimethroughthedoorshowninFigure10.9.Theapparatus,withtheexceptionofthethree-sidedcage,wasplacedwiththesubjectsatleast24hoursbeforetrainingwasbeguninorderthattheymightbecomeaccustomedtoit.Itremainedinthependuringtheentireperiodoftestingsothatallsubjectshadanopportunityforthoroughexploration.

Experimentationwasdividedintothreeparts:preliminarytrainingtomeetacriterion(aminimumof2daysuptoamaximumof12);testingonasetofstandardproblems(6days);andpersistencetesting(1day).

Preliminarytraining.—Preliminarytrainingwascarriedoutintwostages.Inthe

Preliminarytraining.—Preliminarytrainingwascarriedoutintwostages.Inthefirststage,thedogwasreleasedintothepenbyanassistant,whiletheexperimenterstoodbesidetheapparatusholdingadishcontainingateaspoonfulofcookedherringpieces.Thefoodwasplacedonthegoaltablewiththecageinplace,andguidanceandassistanceweregivenasneededtoinducethedogtowalkuparampandobtainfood.Trainingwasgiveninrotationonallrampsuntil,on3consecutivetrials,thesubjectwalkedupandreceivedfoodwithin1minutewithoutanyactualhandlingbytheexperimenter.From3to20trialswererequiredtoattainthiscriterion.

Inthesecondtrainingstage,theapparatuswassetupwithonlyonerampinplace,andthegoalcagewasturnedsothattheopensidecorrespondedwiththisramp.Foodwasplacedinthegoalcage,andtheanimalreleasedintothepen.Theexperimenterremainedoutsidethepen,partiallyconcealedbyawoodenbarrier.Theprocedurewasthesameasthatintestingexceptthattherewasnochoiceoframpstoascend.Rampsandgoal-cagepositionwererotatedaftereachtrialuntil3consecutivesuccessfultrialswerefinished.Asuccessfultrialwasdefinedasreachingthegoalwithin2minutes.Onunsuccessfultrialstheexperimenterenteredandledthesubjecttothegoal.

Testandscoring.—Twodifferentarrangementsoftheapparatuswereemployed.Duringtrainingandthefirstthreedaysoftesting,thetablesweresetupforProblem1asshowninFigure10.9.OnDay4throughDay6theapparatuswasrotated180°.ThiswascalledProblem2.

Thethreepathwaystothegoalweredesignatedas(D)direct

250BREEDDIFFERENCES

ramp;(S)straightrampandbridge;and(L)L-shapedpathoframp,table,andbridge.Theunitofperformancetakenforanalysiswasasetof3consecutivetrials,eachwithadifferentcorrectpath.Twosets(6trials)weregiveneachdayfor6days.Sets1through6onProblem1occupieddays1through3.Sets7through12onProblem2weregivenonDay4toDay6.

Recordsofbehaviorincludedacountoferrorsandtimeinsecondstoacorrectsolution.Errorsweredefinedas(1)climbinganincorrectramp,(2)retreatingfromthecorrectpathway,(3)circling,runningbackandforth,andothermovementsnotpartofadirectprogressionfromramptoramp,(4)leapingdirectlyatthegoaltableortheelevatedbridges,and(5)failingtoleapdirectlydownfromtheelevatedportionofanincorrectpathway.Atfirstanattemptwas

downfromtheelevatedportionofanincorrectpathway.Atfirstanattemptwasmadetorecordeachtypeoferrorseparatelyonadiagram,butitwasfoundthatthevarioustypeswerepositivelycorrelatedandonlysumsaretreatedinthispaper.RepetitionsofType-1errorswithinasingletrialwere,however,recordedseparately,sincethisappearedtorepresentaparticularlymarkedpersistenceofanincorrectresponse.

Thetimebetweentheanimal'sentranceintotheexperimentalfield(definedbyalinedrawn6feetfromtherampnearesttotheentrance)andthereachingofthefoodwasthesolutiontime.Thelogarithmofthistimewasthetimescoreforeachtrial.Theaverageofthesetimescoresgivesthelogarithmofthegeometricalmeanoftheactualtimesinseconds.Alimitof5minuteswassetforeachtrial,butthetrialwasdiscontinuedatanytimewhenasubjectforaperiodof1minuteeitherremainedmorethan6feetfromtheapparatusorstayedinoneplacewithnoattempttosolvetheproblem.

Persistencetest.—OnDay7thesubjectsweretestedforonetrialonProblem2withtheopensideofthegoalcageturnedawayfromthethreeapproachesandcoveredwithawirescreentopreventanydogfromleapingdirectlyontothetable.Adishcontainingfoodwasplacedinsidethecage.Acountwasmadeofthenumberofattemptstogetatthefood.Forthispurposeanyentryontoaramporstandinguptoanypartoftheapparatuswasconsideredasanattempt.Thetestwascontinuedfor5minutesoruntil1minutepassedwithoutanyattemptstoreachthegoal.

Resultsofspatial-orientationtest.—InTable10.8arelistedmeanerrorscores,adjustedtimescores,andpersistencescores,allexpressedinstanines.ThescaleshavebeenorientedsothatahighEscoreindicatesgoodperformance(fewerrors);ahighTscore

TABLE10.8ComparisonsbetweenPureBreedsonSpatial-OrientationScores

*Notincludedinnumbertested.

indicatesaspeedysolutionoftheproblemandhencefastrunning;andahighPscoremanyattemptstoreachthegoalontheinsolvableproblem.Theadjustedtimescores(V)takeintoaccounttheadditionalrunningtimeattributabletoextradistanceproducedbyerrors.Themeanregressionoftimeonerrorswascomputedandtheadjustmentmadeaccordingtothefollowingequation:T'—T—0.0713AT,whereT'istheadjustedtimescore;Tisthetimescoreinlogseconds;andA7isthenumberoferrors.

seconds;andA7isthenumberoferrors.

Beforeconsideringthedifferencesbetweenbreedsindetailsomeofthegeneralfeaturesofthetestwillbeconsidered.Amongthe121purebreddogswhichweretested,16failedpreliminarytrainingandwereeliminated.DisqualificationswereespeciallyprevalentamongtheShetlandsheepdogs,whereonly11outof19couldbetested.Thisbreedalsowasthepoorestperformerintermsoferrors.

TherawerrorscoresforthefivepurebreedsareshowninFigure10.10,whichalsodepictsresultsforthecockerspaniels(mostsuccessful)andShetlandsheepdogs(leastsuccessful).TheconnectedpointsforSet1throughSet6formatypicallearningcurve;errorsrosewhentheapparatuswasrotatedandfellagainafterpractice.ThemoststrikingcurveisthatoftheShetlandsheepdogsonSet7throughSet12.Rotationoftheapparatusproducedaverygreatdecrementinperformancewhichremainedthroughoutthetest.Somesheepdogs,however,performedwell.Figure10.11showstheindividualerrorscoresofthebestandpoorestsubjectamongthem.Theextremeindividualsamongthespanielsarealsoshown.Therangeofperformancewasgreat.SH-2953andCS-2724solvedtheproblemswithaminimumofretracingandrandomactivity;CS-1913showedalearningcurveverymuchlikethegroupaverage;SH-1945didnotimprovesystematically,thoughitscoredwellonTrialSet4.

BREEDDIFFERENCES

20

15-

10

5■

0-

345678910IISETOFTRIALS

12

Fig.10.10.—Rawerrorscoresforthecombinedfivepurebreeds(solidcircles)onthespatial-orientationtestcomparedwithscoresforsheltiesandcockerspaniels(opencircles).

3456789

SETOFTRIALS

10II12

Fig.10.11.—Individualerrorscores,spatial-orientationtest.


253

Despiteindividualvariability,differencesbetweenbreedsinerrorscoresforbothseriesoftestswerefoundtobehighlysignificant(Table10.9).Evidencewasalsofoundforsignificantlittereffectswithinbreeds.Sincethetestwascarriedonoutdoorsundervaryingweatherconditions,itispossiblethatacommontestenvironmentwaslargelvresponsible.

Differencesbetweenbreedsonadjustedtimeandonpersistencewerealsosignificant,althoughlittereffectswerenotfound.Itisevidentthatthebreedswiththehighestscoresonpersistence(P)arenotnecessarilvthosewiththefewesterrorsorfastesttimes.Product-momentcorrelationcoefficientsbetweenpersistenceandperformanceonProblem2areshownbelow:

persistenceandperformanceonProblem2areshownbelow:

E2P,r=.040(degreesoffreedom,88),7YP,r=.259(degreesoffreedom,88).

Thesecondofthesecorrelationsreachesthe5percentsignificancelevel.Itindicatesaslighttendencyforthefasterdogstobemorepersistentinaccordwiththehypothesisthatbothmeasureswerecloselydependentuponmotivation.

TABLE10.9AnalysisofVarianceofSpatial-OrientationMeasures

•Variationsinthenumberoflittersareattributabletoaccidentallossofdataandtovariationsinthenumberofsubjectsgiventhepersistencetest,tP<.05XP<-01

Itis,ofcourse,impossibletoestimatedirectlytherelationofspeedpersetoerrors,sincetheadjustedtimescoreswerecomputedbyaprocesswhichinvolvedsubtractionofthatportionofthetimescorewhichcouldberelatedtoerrorscores,andthenon-adjustedtimescoresarecorrelatedwitherrorsbecauseeacherrorlengthensthedistancerun.Thescoresusedinthestatisticalanalysis,however,weretransformationsoftheactualtimeinsecondsmadetobringthedataintoamorenormaldistribution.Itcanbeshownthattheexpressionforadjustingtimescores,T'=T—bE,isequivalentto

adjustingtheactualtimesbytheexpressionV=t/kE,wheretistimeinseconds.ThecorrectiontermisanexponentialfunctionofEratherthanalinearfunction.Slowdogsdotendtomakemoreerrors,andthecorrectiontermshouldbecorrespondinglyexpandedforhigh-errordogsinordertoadjusttheirtimescorestoanerror-freebasis.

Evenaftertransformationandadjustment1anassociationremainedbetweenhigherrorsandslowtimeswhichisapparentinTable10.8.CorrelationcoefficientswerecalculatedbetweenEiandT'i,E2andT'2afternormalizationofthescoresandseparationofthewithinbreedsandbetweenbreedssumsofsquaresandcrossproductsasfollows:

SampleDegreesofFreedomEiT\EiT'i

Totalsample102.333.349

Betweenbreeds4.610.798

Withinbreeds98.273.079

Withinbreeds98.273.079

Thereisastrongtendencyfortheslowerrunningbreedstomakemoreerrors,butwithinbreedsthecorrelationislowornegligible.Theover-allcorrelationappearstobelargelyspurious.

Effectofpracticeongeneticeffects.—Repeatedtrialsonthespatial-orientationapparatusresultedinincreasedcorrelationoferrorscoresobtainedinconsecutivesetsoftrials.Figure10.12showstheproduct-momentcorrelations(inter-trial)betweenconsecutivesetsforthepurebreddogsasagroup.Thereliabilityofthistestdidnotreachthelevelofourbesttestsasthemaximumcorrelationwasabout.60.Onthesamefigurearedepictedtheintraclasscorrelationscomputedtrialbytrial.Althoughlowerinmagnitude,allintraclasscorrelationsexceptthoseforsets1,3,and6aresignificantatbetterthanthe.01level.Duringthefirstpartoftesting,theintraclasscorrelationsfluctuated,buttheywererelativelysteadyduringthesecondportionofthetestperiod.Itwillberememberedthatanintraclasscorrelationmeasurestherelativecontributionofbreeddifferencestototalvariance.Onemustconcludethattrainingdoesnotdecrease,andpossiblystabilizes,thecontributionofhereditytoindividualvariation.Thepointisimportant,foritissometimesassumedthatchangeinabehaviorpatternfollowingpracticeisevi-

1Thequestionmayberaisedconcerningthevalidityofcorrectingtimescoresbythedescribedmethod.Ascatterplotorerrorsagainstlogtimeshowedgoodfittoalinearrelationasjudgedbyeye.Thecalculatedvalueoftheregressioncoefficientwasabouttentimesitsstandarderror.However,noclaimismadethatthetransformationismorethanastatisticalconvenience,andabettermathematicalmodelmightyieldbetterresults.


255

1.00

LU

5.75

.50

SPATIALORIENTATIONERRORS

O-OINTERTRIAL••INTRACLASS

/°-o

/°^°N

sO

456789SETSOFTRIALS

12

Fig.10.12.—Reliability(inter-trialcorrelation)improvesasthetestprogresses,butbreeddifferences(intraclasscorrelation)remainconstantinthespatial-orientationtest.

denceagainstitsheritability.Theargumentfollowsthelinethatdemonstrationofmodifiabilitybytrainingmakesitunnecessarytoaccountforanyvariancefromheredity.Thelogicofthisargumentisclearlyfalseandexperimentaldatacontradictit.

CONCLUSIONS

Interpretationofmanyoftheseproblem-solvingtestsisrendereddifficultbythefactthatnotallsubjectsmetpreliminarycriteriafortesting.Thesefailureswerenotevenlydistributedamongthefivebreeds,hencetheactualsampleswerebiased.Theeffectwasprobablytodecreasecalculatedvaluesofgeneticeffects,sincethefailurescamepredominantlyfrombreedswhichhadlowaveragescores.

Sincecorrelationsofmeasuresoflearningandofmotivation,particularlyinthespatial-orientationtest,werenothigh,itdoesnotseemlikelythatallvariationsinproblemsolvingweresecondaryeffectsoffearfulnessinthetestsituation.Yetinconductingthetests,theexperimentersoftenobservedavoidingbehaviorinpoor-scoringsubjects.Thepoorperformanceasagroupofbasenjisoncue

poor-scoringsubjects.ThepoorperformanceasagroupofbasenjisoncueresponseandShetlandsheepdogsonspatialorientationappearedtobelargelyafunctionoffearfulness.Thisexplanationdoesnotaccountforpoorscoresofterriersonspatialorientation.

256BREEDDIFFERENCES

Certainlynoevidencewasfoundforageneralfactorofintelligencewhichwouldproducegoodperformanceonalltests.OnthispointweagreewithSearle(1949),whocomparedmaze-brightandmaze-dullratsonavarietyoftests.Thegenetictransmissionofproblem-solvingabilitywillbediscussedinchapter12,butitcanbestatednowthatgeneticcontrolappearstobelargelyamatterofnon-allelicinteractionswithrelativelysmalladditivegeneticeffects.Suchafindingisnotunexpectedwhendealingwithsocomplexaphenotype.

Eachofthedifferentproblem-solvingtestsproducedinterestingideasandresults.Thefirstbarrierordetourtestgivenat6weeksofageindicatedthatthecapacityforinsightorsolvingaproblemwithouttrial-and-errorisdevelopedbyexperienceratherthanappearingspontaneously.Sinceyoungpuppiesatthisagehaveverylittlecapacityforwidegeneralization,theirinsightsarelimitedtoproblemsverysimilartotheirpreviousexperiences.

Themanipulationtestemphasizedtheimportanceofsuccessandfailureinincreasingorreducingmotivation.Onceananimalhaslearnedtofailitisextremelydifficulttogethimmotivatedenoughtomaketheefforttosolveevenasimpleproblem.

Inthemazetestwemadeadetailedanalysisofthevariouseffectsofenvironmentalandotherbackgroundfactors.Theresultssuggestthattheserandom,uncontrolledfactorsareindeedimportantindeterminingproblem-solvingbehavior,aspsychologistshavelongsuspected.However,therestillremainedinthistestahardcoreofvarianceattributabletobreeddifferencesandthustoheredity.

Thecue-responseanddelayed-responsetestswereunusualinthattheyshowednobreeddifferences,butdidindicatewideindividualdifferences.Theseweretestswhichmostclearlydependedonpureintelligence.Theresultsindicatethatinthisareaindividualdifferenceswithinabreedmaybemoreimportantthandifferencesbetweenpopulationmeans.

Thetrailingtestemphasizedtheimportanceofemotionalfactorsindetermining

Thetrailingtestemphasizedtheimportanceofemotionalfactorsindeterminingperformance.Thebasenjisshowedafearofstrangeobjectswhichaccountedforalmostallthebreeddifferencesshowninthistest.Thesamereactionaffectedtheirbehaviortoalesserextentinanyofthetestsinvolvingstrangeapparatus.

Finally,thespatial-orientationtestshowedthatpracticeneednotreducegeneticvariation.Whilethetotalvariancemightbereducedastheanimalsbecomemoreexpert,theproportionofvarianceattributabletobreedsremainedconstant.

Withtheexceptionofthecue-responseanddelayed-response


tests,allthetestsshowedclear-cutbreeddifferences,manyofthemquiteimportant.Thisfindingraisestheproblemofwhethertherearegeneraldifferencesinintelligencebetweenthebreeds.CanwetakethesumofthesetestsasasortofcanineIQanddeterminetherelativecapacitiesofeachbreed?

Inthefirstplace,ahumanintelligencetestincludesdozensandsometimesahundredormoreproblemswhichthestudentsolveswithinanhourorso.Thisispossiblebecausethestudentshavebeensubjectedtoyearsofprevioustraininginsimilarproblems,anditismeaningfulbecausetheireducationalandenvironmentalbackgroundshavebeenreasonablysimilar.Comparingsuchatestwithourproblem-solvingexperimentswithdogs,itisfairtosavthateachofthecaninetestsisequivalenttoasinglequestiononanIQtest.Furthermore,thetestsaredoneatdifferenttimesanddifferentages.Itisimpracticaltogivedogsthesamevarietyandintensityoftrainingtowhichhumanpupilsaresubjected.Forallthesereasons,thecanineresultsaremuchlessaccuratethanthoseobtainedbyahumanIQtest.

Nevertheless,itisinterestingtoputalltheresultstogetherandlookattheover-allpicture(seeTable10.10).Inthefirstplace,thereisnobreedwhichcomesoutuniformlvwiththehighestrank.Evenonindividualtests,abreedmaybefirstinonepartandlastinanother.Inthemazetest,forexample,beaglesachievedthebestminimumscoresbutperformedbadlvonthefirsttrial.

Ingeneral,thefourhuntingbreeds(beagles,basenjis,terriers,andcockers)performedbestonthetests.Thisisprobablvbecausemostofthetestsweredeliberatelydesignedtotestindependentcapacitiesmotivatedbyfoodrewards;anditisnoteworthythatthebeagle,whichisnormallyusedforhuntingwithoutdirection,showsthebestover-allperformanceintermsofnumberoffirstranks.

direction,showsthebestover-allperformanceintermsofnumberoffirstranks.Bycontrast,theShetlandsheepdogs,whoseancestorshavebeenselectedfortheirabilitytoperformcomplextasksunderclosedirectionfromtheirhumanmasters,performedratherbadlv.Indeed,inmanyofthetests,thesheltiesgavethesubjectiveimpressionofwaitingaroundforsomeonetotellthemwhattodo.Furthermore,whileallthehuntingbreedsarestronglymotivatedbyfood,sheepdogsingeneralhavebeenselectedawayfromthistrait.Thedifferencebetweensheltiesandotherbreedsinthisrespectisstronglybroughtoutinthesimpletaskofrunningtoafoodreward(seeFig.9.4).

Obviously,abetteranswertothequestionofdifferencesinproblemsolvingabilityneedstobefound.Suchexperimentswouldin-

258BREEDDIFFERENCES

TABLE10.10RanksoftheDifferentBreedsinVariousProblem-solvingTests

Test

Detourtest:

Shortbarrier

Longbarrier

U-barrier

Manipulationtest:

Movingdish

Stringpulling(1)

Stringpulling(2)

Uncoveringdish

Mazetest:

Speed

Minimumerrors

Lackofhabitformation

T-mazeanddelayed-responsetests

Speed

Discrimination

5-seconddelay

Trailingtest:

Success,mostdifficulttrial....

Speed,mostdifficulttrial

Spatial-orientationtest:

Fewerrors

Speed

Persistence

Totalfirstandsecondranks.

Breed

Basenji

Beagle

Cocker

Sheltie

FoxTerrier

555

3244

555

555

13

4.53

2

222

2422

243

2

22

4

5

4.54.53

10

eludemoreofthebreedswhicharethoughttobeunusuallyintelligent,suchaspoodlesandbordercollies,andthetestingprogramshouldincludetrainingforcomplextaskssimilartothoseforwhichthesebreedsareusuallyemployed.Onthebasisoftheinformationwenowhave,wecanconcludethatallbreedsshowaboutthesameaveragelevelofperformanceinproblemsolving,providedtheycanbeadequatelymotivated,providedphysicaldifferencesandhandicapsdonotaffectthetests,andprovidedinterferingemotionalreactionssuchasfearcanbeeliminated.Inshort,allthebreedsappearquitesimilarinpureintelligence.Ontheotherhand,wehaveevidencefromthedelayed-responsetestthatthereareenormousindividualdifferenceswithinbreedsfordevelopingcertaincapacities.Whetherornottheseareinheritedcanonlybedeterminedbyselectionandcrossbreedingexperimentswithinbreeds.

PARTIII

INHERITANCE

OFDIFFERENTIALCAPACITIES

AMONGHYBRIDS

CHAPTER11

THEINHERITANCEOFBEHAVIORPATTERNSSINGLE-FACTOREXPLANATIONS

Aswepointedoutinchapter3,thebehaviorofdogshasbeenprincipallymodifiedinconnectionwithagonisticandinvestigativebehavior.Thelatterisdifficulttomeasureunderlaboratoryconditions,sincemostoftheinvestigativebehaviorofdogshastodowithhuntingandcanonlybeseenadequatelyunderfieldconditionswhereitisalmostimpossibletokeeprandomenvironmentalfactorsfrominterferingwithanexperiment.Furthermore,manyofthesepatternsofhuntingaredevelopedonlyafterextensivetraining.

Ontheotherhand,thepatternsofagonisticbehavioraremucheasiertostudy,sincetheyappearoverandoveragainunderlaboratoryandkennelconditions.Thetwobreedswhichwerechosenforthecrossshowedwidedifferencesinthisrespect.Cockerspanielshavebeenselectedfornon-aggressiveness.Occasionallya"mean"cockerwillappearinthebreed,butthisisconsideredaseriousfault,andsuchanimalsarenotusedforbreeding.Shynessortimidityisalsoconsideredafaultinthisbreed,asitisinmostothers,sothatcockerspanielsasagrouparerelativelynon-aggressiveandconfidentintheirrelationstopeople.

Thebasenjibreedisbycontrasthighlyaggressive,althoughnotsomuchsoasthewire-hairedterriers.Whenfirstdiscovered,basenjisweresometimescalled"Congoterriers."Alsoincontrasttothecockers,youngbasenjisrearedunderourconditionsshowedagreatdealoftimidityat5weeksofage:runningaway,yelping,snappingwhencornered,andgenerallyactinglikewildwolfcubs.ItisprobablethatintheAfricanjunglevillagessuchwarinesshasconsiderablesurvivalvalue.Inspiteofthisearlytimidity,basenjipuppiestamedownveryrapidlywithhandlingandhumancontact.

262DIFFERENTIALCAPACITIES

GENETICANALYSISOFBEHAVIORALTRAITS

GENETICANALYSISOFBEHAVIORALTRAITS

Ouroriginalpredictionwasthatallbehaviortraitswouldprovetobeaffectedbymanygeneticfactors;i.e.,bypolygenicsystems,andwethereforedesignedourexperimentsothattheresultscouldbeanalyzedaccordingtotherelativeamountsofvariationproducedbygeneticfactorsinthehybridsandpurebreeds(Chapters12,14).Astheresultscamein,however,wefoundthatsomedifferencesinbehaviorpatternsseemedtobeinheritedasiftheywereproducedbyoneortwogenes,sothattheresultsofthecrosslookedlikethosefromasimpleMendelianexperimentandverysimilartothoseobtainedfrommeasuringasimplephysicaltraitinthesamecross.Forexample,allbasenjisareshorthairedandallcockersarelonghaired.Whenthetwobreedsarecrossed,thepuppiesintheFigeneration,whetherfromcockerorbasenjimothers,allhaveshorthair,indicatingthatshorthairisdominantoverlong.Ifthisresultisproducedbyasinglegene,wewouldexpectthatthebackcrosstothebasenjiswouldallhaveshorthair,thatapproximatelyone-halfofthebackcrosstocockerswouldhavelonghair,andthatone-fourthoftheF2?swouldalsohavelonghair.Asshowninchapter13,thiswasactuallythecase.

Inmanyexperimentswiththeinheritanceofphysicaltraits,earlyexperimentersdeliberatelychosecharacteristicsinwhichtherewasnooverlapbetweentheparentstrains,simplyforconvenienceandeaseofanalysis.However,wewereunabletofindanysinglebehaviortraitinwhichtherewasnooverlapbetweenthebreeds.Aswehavepointedoutbefore,selectionhasemphasizedorde-emphasizedcertainbehaviortraitsbuthasnotcreatedanythingnew.Inmanycasesselectionhassimplymodifiedtheamountofstimulationrequiredtobringoutaparticularbehaviortrait.Basenjiscanbestimulatedtofightwithrelativeeaseandcockersonlywithdifficulty,butitisquitedifficulttofindanamountofstimulationwhichwillcause100percentofbasenjistobecomeaggressiveandleaveallcockersunaffected.Consequentlythereisalwayssomeoverlapbetweenthebreeds.Thismeansthatwhenweanalyzetheinheritanceofbreeddifferencesinbehaviorwearealwaysforcedtoworkwithdifferencesrangingfrom50to90percentandtoallowforconsiderablevariabilitywithineachbreed.WecanneverthelesscomparetheresultswithmodelsofsimpleMendelianinheritanceinvariousways,andthischapterdescribestheoutcomeofsurveyingthedataontheassumptionthatsomeofthedatamaybeexplainedasa

BEHAVIORPATTERNS263

resultofsingle-factorinheritanceanddiscontinuousvariationratherthan

resultofsingle-factorinheritanceanddiscontinuousvariationratherthanmultiple-factor(polygenic)inheritanceandcontinuousvaria-

tion.

METHODSOFGENETICANALYSIS

ThechiefpurposeofexperimentswithhvbridizationistodiscoverwhetherornotthepatternofinheritancefollowsMendeliantheory.Herewehaveachoiceofanalvsisbytwomethods:quantitativeinheritanceorqualitativeinheritance.Mostofthebehavioraldatalookslikecasesofquantitativeinheritance,sincebehaviorisusuallymeasuredoncontinuousscalesoffrequency,latency,orspeed.Ontheotherhand,therearecertaincasesinwhichbehavioriseitherpresentorabsentandapparentlyconsistentwithqualitativeinheritance.Fromamathematicalviewpointthesetwotypesofdatacanbedescribedasbeingdistributedeitherinmultiplecategoriesoralternatecategories.Thelatterisoftenreferredtoasadichotomousdistribution,incontrasttoacontinuousdistribution.Whicheverdistributionispresent,thedatamustgiveindicationsofbeingexplainablebyareasonablysimpleMendelianhypothesisinordertomakepossibleanyfurtheranalysisalongtheselines.

Quantitativeinheritance:analysisofvariance.—Castle&Wright(Castle,1921)developedaformulaforestimatingthenumberofgenesinvolvedinaparticularcross,basingtheircalculationsontwomajorassumptions.Thefirstoftheseisthatthegeneshavesimpleadditiveeffects.Suchanassumptionisoftenareasonableone,asitisinthecaseofthenumberoftimeswhichadogjerksontheleashduringtraining.Ifonegenecausesacertainnumberofjerks,thenasecondgenemightwelladdafewmore.Ifthesecondgeneshouldinsteadcauseapercentageincreaseinthenumberofjerks,transformingthedataintoastaninescalewillcausethiseffecttoappearadditive.

Thesecondassumptionisthateachgenehasaneffectequaltothatofeveryothergene.Thisisapureassumption,andthereisnowayofverifyingitunlessthegenescanactuallybeidentified.Thismeansthattheresultofsuchanalysisalwaysgivesanestimate,andaminimumestimateatthat.Theformulathereforecanbeusedmostconservativelytodistinguishbetweensingle-factorandmultiple-factorinheritance.

Becauseoftheseassumptionsthemethodhascertainlimitations.Itwillnothandlecasesofcomplexinteractionbetweengenessincetheanalysisofsuchaninteractionrequiresthatthepresenceor

interactionrequiresthatthepresenceor


absenceofeachgeneberecognizableinsomeway.Also,itwillnotapplytocertainspecialpatternsofinheritancelikethatseeninplayfulaggressiveness,wheretheFi'sandF2'sshowthesameamountofvarianceandoverlapbothparentstrains(the"Tryoneffect").

TheformulasforanalyzingbackcrossandF2generationsaregiveninTable11.1InthisnotationAisthedifferencebetweenthemeansoftheparentgenerations,andor2isthevariancefromthemeanofeachpopulation.Mather's(1949)formulaforKisamoregeneralformofthesemathematicalstatements,butitsuseisstillsubjecttothesamelimitations.

Asappliedtoourparticularexperiment,certainmodificationsneedtobemade.Oneisacorrectionfordifferencescausedbymaternaleffectsand/ortheselectionofdifferentparentsinthereciprocalcrosses.ThiscanbedonebysubtractingthedifferencebetweenthemeansoftheFi'sfromthatoftheparents,leavingonlythetruebreeddifferences.Inaddition,thevariancecausedbythesameeffectscanberemovedbysubtractingthevarianceduetothedifferencebetweenthemeansofreciprocalcrossesintheFiandF2generations.ThemostaccurateestimateofthenumberofgenesinvolvedisthatbasedonthecorrectedvariancesoftheFiandF2populations,sincewehavethelargestnumbersinthesetwogroups.Workingformulasforthesecorrectionsaregivenbelow:

A=(xPl-xP)-(xBCsf1-Xcsbf)

9_nlV2BCSFi+n2(T2cSBFi<Jp—

Fln

ap—

1n

QualitativeorSimpleMendelianInheritance.—Thefollowingmethodscanbeappliedonlywherethereissomeevidenceofarealdiscontinuityindistributionsuchthatthedatacanbelegitimately

BEHAVIORPATTERNS265

BEHAVIORPATTERNS265

dividedintotwocategories.Theyapplyparticularlywelltocasesinwhichmeasurementsarebasedonthepresenceorabsenceofabehaviorpattern,andanimalscanbeclassifiedaseithershowingthepatternornotshowingit.Sincetransformingthedataintothestaninedistributionwillinevitablyobscurethepointsofdiscontinuity,thebestevidencefortheexistenceoftwocategoriescomesfromtherawdata.Herewearefacedwithanewdifficulty;nowhereinourdatawasthereacaseinwhichtherewasnooverlapbetweenthetwoparentstrains.Wearethereforefacedwiththeproblemofmodifyingthemethodsusuallyappliedtotheanalysisofqualitativeinheritance.

Inadichotomousdistribution,themeanisalwaysthesameastheproportionofindividualsinoneclassortheother;i.e.,inapopulationcomposedof0.5animalsshowingatraitand0.5notshowingit,themeanis0.5.Itisalwaysthemean,orproportion,whichisusedintheconventionalanalysisofdatafallingintotwocategorieswithnooverlapbetweentheparentstrains.

Wecanextendanalysisbycomparisonofmeanstopopulationsinwhichoverlapexists,usingthefollowingformulabasedonacomparisonbetweenthemeansofbackcross(BX)andparent(P)strains,

——>or—-z

UpxPl—xPl

Table11.2givestheexpectedratiosforvariousnumbersofgenes.Thecalculatedfiguresarethesamewhetherornotdominanceisactuallyinvolved,sincedividingthedataintotwocategoriesineffectassumesdominance.Ifonlyonefactorisinvolved,thefigureisthesamewhetherornotheterozygosisispresentintheparentstrains(Scott,1954).Thereforethismethodprovidesatestofasingle-factortheorywhichcanberapidlyappliedtoanydata.Onecanalsousetheformulatocalculatetheoreticalratiosinthesegregatinggenerations,basingestimatesontheempiricaldifferencebetweentheparents.Naturally,thevalidityoftheresultswilldependonthesizeandrepresentativenessofthesamplesmeasured.AsimilarformulacanbeappliedtothedifferencesbetweentheFiandF2means,withthelimitationthattheexpecteddifferencesarenotasgreat.However,inourexperiment,thesearethelargestpopulationsanddeserveattention.

Liketheformulasforquantitativeinheritance,thesemustalsobecorrectedfor

Liketheformulasforquantitativeinheritance,thesemustalsobecorrectedfordifferencesduetomaternaleffectsandaccidentalselectionofdifferentstrainsinreciprocalcrosses.Thiscanbedone

DIFFERENTIALCAPACITIES

TABLE11.2

TheoreticalRatiosfortheDifferencebetweenBackcrosses,

andtheDifferencebetweenFVsandF2's,Comparedtothe

DifferencebetweentheMeansofParentalStrains

bysubtractingthedifferencebetweentheFipopulationsfromboththatoftheparentalandbackcrosspopulations.InthecomparisonofFiandF2populations,thiscorrectioncanbeeliminatedontheassumptionthatbothareequallyaffected.ThecalculationismadebysimplysubtractingthemeanofthecombinedF2SfromthatofthecombinedFipopulations.

ThisgeneralmethodwillalsoapplytotheTryondistribution,inwhichtheFiisas\ariableastheF2andthereappearstobeacentralthreshold.ThereisnodifferencebetweenthemeansoftheFiandF2,butthatbetweenthetwobackcrossesgivesanestimateofthenumberofgenesinvolved(seeTable11.2).

Thelimitationsofthemethodarequitesimilartothoseofanalysisofvarianceappliedtoquantitativeinheritance.Thebasicassumptionsarethoseofequalandadditiveeffectsofgenes,atathresholdinthiscaseinsteadofoveranextendedscale.Likethequantitativemethod,thisonewillnotapplyifgeneeffectsarenon-additiveorextremelyunequal.Theformulahastheadvantage,particularlyusefulwithourdata,ofnotbeingaffectedbyheterozygosityintheone-factorcase(Scott,1954).Inshort,liketheCastleandWrightmethod,itchieflyprovidesatestofsingle-factorversusmultiple-factorinheritance,andthenumberofgenesbevondoneisonlyaminimumestimate.

THEINHERITANCEOFWILDNESSANDTAMENESS

Therelativewildnessofthebasenjisisexpressedintwoobvioustrails.Oneisinavoidanceandvocalizationinreactiontohandlingas

BEHAVIORPATTERNS

267

youngpuppies,andtheotheristhetendencytostruggleagainstrestraint,whichappearsinmanydifferentsituations,butisparticularlymarkedinleashtraining.

Bothcockerspanielsandbasenjis,however,arereadilytameableasyoungpuppies.Thegeneraltraitoftameabilityisabasicone,becauseitmusthavebeeninvolvedintheoriginaldomesticationofthedog.Ifdomesticationoccurredbutonce,itislikelythattherewasanearlyselectionforwhatevergenesfortamenesswerepresentinwildwolvesatthattime,andthatthesegeneswouldthenceforwardbepresentinalldogbreeds.Ifdomesticationoccurredmorethanonce,orifdomesticationoccurredfrommorethanonespecies,wewouldexpectthatdifferentgenesmightbeinvolved.Ifthisweretrue,thereisapossibilitythatanFicrossmightbemuchwilderthaneitherparent,or,ifbothfactorsfortamenessweredominant,thatexcessivelywildindividualswouldappearintheF2orotherhybridgenerations.

Inheritanceofavoidanceandvocalization.—Wemaythinkofthehandlingtestasaseriesofmildtostrongstimulationswhichmaycauseayoungpuppytobefearful.Thestrongeststimulusisthatofwalkingrapidlytowardthepuppy,andtheweakestiswalkingawayorkneelingwithanoutstretchedhand.Thetestscorereflectsthenumberoftimeswhichsuchstimulationpushesthepuppyoverathresholdintothefearfulbehaviorofrunningawayoryelpingwithfright.Somepuppiesbecomefearfulonlyunderthestrongeststimulation,whileothersreactwithfeartoanythingwhichthehandlerdoesandtherebyreceivemuchhigherscores.

table11.3

ScoresforAvoidanceandFearfulVocalizationat5WeeksofAgeinResponsetoaHumanHandler


AscanbeseeninTable11.3,about62percentofthecockersshownofearfulreactionsatall,whereasallbasenjisshowatleastsomefearfulbehavior,withagreatdealofvariabilityintheamountproduced.TheFigenerationisverysimilartothebasenjis,withonlyoneanimalshowingnofearfulreactions,andwecanthereforeconcludethatthedifferencesareproducedbyoneormoredominantgenes.Onthisbasiswecanconstructthehypotheticalresultsofasingledominantgene.Thebackcrosstothedominantbasenjisshouldbelikethe

singledominantgene.Thebackcrosstothedominantbasenjisshouldbelikethebasenjis,whereasthebackcrosstotherecessivecockersshouldbeintermediate.Finally,theF2*sshouldbehalfwaybetweenthebasenjiandcockerbackcross.

Theactualobservedpercentagesfitthishypothesisfairlywell,andbetterthantheyfitthatoftwodominantgenes.Onthebasisofthisevidence,wecansaythatasingledominantgenecausingwild-nessinthebasenjiaccountsfortheobservedresultsreasonablywell.

Consequently,thecontrastinggenefortamenessinthecockersmustbearecessiveone.Thisfitsourgeneralideasaboutmutations,since,inallanimalandplantspecies,mostofthewild-typegenesforstructureandcoloraredominantratherthanrecessive.Also,theFihybridsdonotshowexcessivewildness,indicatingthatbothcockersandbasenjishavethesamegeneralgenesfortameness.Thisisevidenceinfavorofaremotecommonancestryforbothbreeds,althoughitcannot,ofcourse,excludethepossibilityofseparatedomesticationswhichacquiredthesamegenesfortamenessfromthewildwolfpopulation.

Inheritanceofthetendencytofightandjerktheleash.—Intheroutineofour"SchoolforDogs,"thepuppieswerecarriedeverywhereuntiltheywere16weeksofageandwerereadytobemovedoutdoors.Atthistimebothdistanceandtheirincreasingsizemadeitnecessarytoteachthemtofollowonaleash,asdescribedinchapter9.Beaglesandcockerspanielsusuallywentalongreadilyandpeacefully,butbasenjisoftenpulledbackstronglyontheleash,attemptedtobiteitintwo,orjumpedintotheair,shakingtheirheadslikeatroutontheendofafishingline.Oneofthescoresobtainedfromthisbehaviorwasthenumberoftimesthataparticularpuppyfoughttheleash.Thefinalresultsshowedbigdifferencesbetweencockerspanielsandbasenjis(Table11.4).Furthermore,therewerelargedifferencesbetweenthetwoFipopulations,thehybridstendingtoactliketheirmothers.Thisdifferencewascarriedonintothesecondgenerationtoalesserdegree.Itlooksasifthereisanimportanteffectofeitherthematernalenvironmentordifferencesbetweentheparentsofthereciprocalcrosses.Theformerseemsat

BEHAVIORPATTERNS

TABLE11.4TendencytoBiteandJerkLeash(inStanines)

269

269

BreedorHybrid

Basenji

CSBF,

Backcrosstobasenji.CSBF2

Cockerspaniel

BCSFx

Backcrosstococker.BCSF2

Variance

1.86

0.681.021.82

1.600.781.931.69

firstglancemostlikelybecauseofthestrongresemblancestotheirmother'sbehaviorinbothgenerations,butthisisnotcorrect,aswillbeshownlater.

Nevertheless,thereisstillevidencethatbiologicalheredityhasaneffect,becausethehybridsarenotexactlyliketheirmothers,andthereisincreasingvariabilityinthebackcrossandF2generations,aswewouldexpectfromMendeliansegregation.

InspectingthedatawecanformthehypothesisthatthegeneticfactororfactorsinvolveddonotshowdominanceandthatwearethusdealingwiththesimplestformofMendelianinheritance.Whenthedataareanalyzedbythequantitativemethod,estimatesofthenumberofgenesinvolvedcanbeobtainedfromthebackcrossandF2generations.Theseagreefairlywellwitheachother,forwederivethefigure1.07fromtheF2dataandtwoestimatesof1.60and0.48fromtheseparatebackcrosspopulations.Averagingthebackcrossestimatesgives1.04,andwecanconcludethattheinheritanceofthedifferenceinbehaviorbetweencockersandbasenjiscanbeexplainedbyonegenewithnodominance,complicatedbylargedifferencesbetweenreciprocalcrosses(seealsochap.12).

complicatedbylargedifferencesbetweenreciprocalcrosses(seealsochap.12).

INHERITANCEOFOTHERPATTERNSOFAGONISTICBEHAVIOR

Playfulaggressiveness.—Inthehandlingtestsgivenat13and15weeksofage,acharacteristicreactionofthepuppieswastorushtowardthehandler,leapingagainsthimorupathishands,andnippingplayfully.Whenpatted,thepuppyusuallyturnedaroundandpawedorwrestledwiththehand,chewingonitgently.Itisobviousthatapuppyofthisagereactstoanoutstretchedhumanhandinmuchthesamewayasitreactstotheplayfulapproachofanotherpuppy.Whentwodogsinteractinthiswaytheyrearup,


throwtheirforepawsaroundeachother'snecks,andattempttowrestleeachothertotheground,bitingandchewingoneachother'snecksandears.

Aswehaveseeninanearlierchapter,cockerspanielshavebeenselectedagainstviolentaggressivebehaviorintwoways.Oneisbyselectionforcrouchinginresponsetoanupraisedhand,andtheotherisforthehighlyrestrainedbitingor"softmouth"usefulinretrieving.Aswemightexpect,cockerspanielsrespondtohandlinginamuchmoresubmissiveandlessviolentwayandconsequentlyreceivelowerscoresforplayfulfightingthandobasenjis.

Whenwegraphthescoresofthecockers,basenjis,andhybrids,wefindapatternofinheritancewhichisdistinctlydifferentfromanyofthosewehavesofarexamined(Fig.11.1).Mostofthebasenjisre-

T

67STANINE

PLAYFULAGGRESSION

Fig.11.1.—Distributionofstaninescoresforplayfulfightingat13-15weeksofage.NotethehighlyvariableFx,overlappingthecompleterangeofbothparentbreeds.Arrowsindicatemeans.

ceivehighscoresforaggressiveness,andmostofthecockersreceivelowscores.Unexpectedly,theFihybridsincludebothhighandlowscoresandarchighlyvariable,andtheF-'sareverysimilartotheFi's.Thebackcrossestothebasenjishavealargepercentageof

aggressiveanimals,andthebackcrossestothecockershavealowpercentage.

Fromtheviewpointofgenetictheory,wewouldexpectthatbothpurestrainswouldshowlittlegeneticvariability.Likewise,thefirstgenerationhybridsshouldallhavethesameheredity,eachanimalreceivingthesamegenesfromeitherparent.TheF^'s,ontheotherhand,shouldbegeneticallyvariable,becausethegeneshavebeensegregatedorsortedoutintotheparentalandhybridtypes.Inthisactualcasetheparentbreedsarevariable,theFi'sarehighlyvariable,andtheF2'snomorevariablethantheFi's.HowcanwereconcilethiswiththetheoryofMendeliangenetics?

Thesimplestexplanationisthatwearedealingwithathresholdofresponsetostimulation.Thepuppiesareeitherstimulatedtoplayfulfightingornot.Iftheyhavealowthreshold,asinthebasenjis,theyreactwithplayfulbitingandchewingtotheslightesthumanstimulus,butiftheyhaveahighthresholdlikethecockers,theyrarelyreachthisthresholdanddolittlebitingorchewing.TheFi'shaveanintermediatethreshold;sothatthismayormaynotbereachedduringthetest.ConsequentlytheFi'smayshoweitheralargeamountofplayfulfightingoralmostnone,justasinthetwoparentaltypes.Thesecondgenerationhybridsshouldcontainallgenetictypes;buttheintermediateones,orheterozygotes,shouldrespondinthesamewayastheFi's,sothattheF2generationwillshowvariabilityexactlyliketheFi.Ontheotherhand,eitheroftheback-crossgenerationsshouldhavefeweroftheintermediateorheterozygoustypesthantheFi'sandconsequentlybemoreliketheparentgenerations.

Theonlywaytoestimatethenumberofgenesinvolvedistocalculatetheexpectedandobserveddifferencesbetweenthetwoback-crossgenerations.Forexample,ifonlyonegeneisinvolved,50percentofthebackcrossshouldbeheterozygous,andaccordingtoourtheoryhalfoftheseheterozygousanimalswouldfallintoonetypeandhalfintheother.WheretheFi'sarehalflikeoneparentpopulationandhalfliketheother,andonlyonegeneisinvolved,theback-crossshouldbethree-fourthslikeoneparentandone-fourthliketheother.Iftwogeneswereinvolved,onlyone-fourthofthebackcrosswouldbeheterozygous,whichwouldmeanthatthebackcrosswouldbeseven-eightslikeoneparentandone-eighthliketheother(Table11.2).

Thetheoreticalresultsmustbeadjustedtoallowforthefactthatthereissomeoverlapbetweenthetwopurebreeds.Theobservedre-


suitisclosertothatexpectedfortwofactors,inwhichtheback-crossesarequitefarapart,thanitisforonefactor.Wecanconcludethattheinheritanceofthisparticulartraitcanbeexplainedbythehypothesisoftwogenes,eachofwhichlowersthethresholdofstimulationbyapproximatelythesameamount(Fig.11.2).This,of

70-i

£soH

40H

30

20

\o-\

01020H

30

40-i

50

50

60

70-

80-

THRESHOLDOF

STIMULATION

BABX/B

BX/CSCS

INHERITANCEOFPLAYFULAGGRESSIVENESSINPUPPIES

Fig.11.2.—Theoccurrenceofplayfulfightingtransformedtoascaleofthresholdofstimulation.Thisgraphisbasedonrawscores,withathresholdarbitrarilylocatedatthepointofmaximumseparation.Scoresforthepurebreedsarebasedonlyonthoseanimalscloselyrelatedtothehybrids.NotethatFjandF2arealmostidenticalandintermediatebetweenthetwoparentstrains.

course,doesnoteliminatethepossibilitythatthereisamorecomplextypeofinheritanceinvolved.Ourresultsindicateonlythattheresultscanbeexplainedonthebasisoftwogenesactinginthemannerdescribedabove.

Thisunusualbutbasicallysimplesortofinheritanceturnsupfairlyfrequentlyinbehavioraldata.ItwasprobablyoverlookedintheearlyclassicalstudiesofMendeliaogeneticsforseveralreasons.

BEHAVIORPATTERNS273

Onewasthefactthattheearlygeneticistswereinterestedprimarilyinthemodeofchromosomaltransmissionratherthanthenatureofanyparticulartrait,andsotheyusuallydisregardedanyinheritedtraitwhichdidnotgiveclear-cutdifferencesbetweenstrains.Anotheristhatthresholdphenomenaaremuchmorefrequentandmoreobviousintraitsofbehaviorthanintraitsofformandcolor,althoughthegeneticsofcolorcanalsobeanalyzedintermsofthresholds.Amousemaybeeithercompletelycolorless(asinanalbino)orallblack,andwecansaythatthereisathresholdforthebiochemicalprocessofpigment

cansaythatthereisathresholdforthebiochemicalprocessofpigmentformationwhichisreachedonlywhenaparticulargeneispresent.However,itisdifficultorimpossibleforanenvironmentalfactortoaffectthisthresholdinsuchawaythatamousecouldbeshiftedfromonecolortoanotherbyanenvironmentalaccident.Abetterexampleistheinheritanceofthenumberofsacralvertebraeinthemouse,wherecertainpuregeneticstrainshavevariablenumbersofsuchvertebrae,presumablyproducedbyrandomenvironmentalfactorsactingearlyinembryonicdevelopment.Theconceptofathresholdraisedorloweredbygeneactionandenvironmentalfactorsisthereforebasicingenetics.

Inordertohavethetypeofinheritanceshowninthisexample,withahighdegreeofvariabilityinbothFi'sandF2*s,theremustnotonlybeathresholdbutonewhichiseasilyaffectedbyenvironmentalfactors,conditionswhicharealwayspresentinbehavior.IftheFihybridsfallclosetothethreshold,theabovepatternofinheritancewillautomaticallyappear.

Thefrequencyofthiskindofinheritanceisthereforedependentnotonlyonthresholdsbutonthefactthatthesethresholdsareeasilyaffectedbyenvironmentalfactors.

Barklessness.—Oneofthestrikingcharacteristicsofthebasenjibreedisthefactthatthesedogsrarelybark.Wecanonlyspeculateastowhythistraitwasdeveloped,sinceitwasalreadypresentinthebreedwhenitwasbroughtoutofAfrica.Itispossiblethatbarking,whichisanalarmsignalgivenbydogswheneverastrangeanimalorpersonapproachestheirhometerritories,isnotconducivetosurvivalintheAfricanforests.Leopardsarereputedlyfondofdogmeat,anditmaybethatthedogwhichbarkssimplyattractsattentiontohimselfandcomestoanuntimelyend.AlthoughtravelershavedescribedbasenjisasbeingverynoisyintheirnativeAfricanhabitat,especiallyatnight,noneofthesoundsproducedarelikebarks,beingvariouslydescribedas"crowing,""yowling,"and"howling."Thissuggeststhatthebasenjismayhavedevelopedsoundswithunusualacousticqualities.Thebarkingofmostdogs,as


analyzedonthesonograph,consistsofasuccessionofshort,sharp,monotonoussounds,whichareveryeasytolocalize.Thatis,barkingconveysaccurateinformationastothelocationofthebarkinganimal.Ontheotherhand,soundswhichvaryinpitch,loudness,anddurationaremuchmoredifficulttolocalizewithrespecttodirectionanddistance,asanyonewhohashadexperiencewith

withrespecttodirectionanddistance,asanyonewhohashadexperiencewiththevocalizationsofcoyoteswillrecognize.Whiledistinctlydifferentfromcoyotes,thebasenjisoundshavesimilarqualitiesofvariabilityandmayservethesameadaptiveandprotectivefunction.Inanycase,basenjisbarkverylittlecomparedtootherdogbreedsand,wheneverdifferentbreedsofdogslivetogether,thebasenjis'relativesilenceisextremelynoticeable.Asastrangerwalksbythedogrunsatourlaboratory,achorusofbarksarisesfromagroupofcockerspanielsandfromanearbygroupofShetlandsheepdogs.Inapenbetween,alitterofbasenjislookupwithoutopeningtheirmouths.

Darwinthoughtthatwolvesdonotordinarilvbarkandthatwhentheydoitisbecausetheyhavelearnedthehabitfromdogs.Allmodernobserversofwolvesunderanyconditions,whetherinzoosorintheremotewilderness,agreethattheybark,althoughnotasmuchasmanydogbreeds.Thebarklessnessofbasenjisisthereforenotaprimitiveancestraltraitbutratheranewandunusualcharacteristic,producedbysomesortofselection.

Ourbestdataontherelativebarkingcapacitiesofthedifferentbreedscomesfromthedominancetestinwhichwetookeachpairoflittermatesandletthemcompeteforaboneduringaperiodof10minutes.Whilethevweredoingthiswerecordedthevocalizationsofeachanimal,includingbarks,whines,andgrowls.Wehavesuchdatafrom5,11,and15weeksofage.AscanbeseenfromFigure11.3,themaximumamountofbarkingoccursat11weeksinallbreeds,withthepossibleexceptionoftheShetlandsheepdogs,inwhichtheamountofbarkingseemstobestillrisingat15weeks.Thegraphalsoshowsthatthecockerspanielsat11weeksdothemostbarkingofanybreedandthebasenjisdotheleast.

Obviously,basenjis(oratleastthestrainwhichwehave)arenotcompletelybarkless.Whensufficientlvexcited,theywillbark.Table11.5showsthatbasenjisbarkedduring20percentoftheopportunitiesgiventhemduringthedominancetest,whereasthecockerspanielsbarkedduring6Spercent.Thebasenjisusuallygaveonlyoneortwolow"woofs"whentheydidbark,theaveragenumberbeingabouttwo.At11weeksofage,thelargestnumberofbarksgivenbyanybasenjiduringthedominancetestwas20,andthenexthighestnumberwas12.Morethanthis,thesoundwhichthebasenjis

BEHAVIORPATTERNS

275

200180160

C/M40J

or

<I20CD

6loo

8060

4o^

20

/\

/

//

//////

//...:^:;

\

\

/

\

/

\

•cs

•BEA

••SH

••WH

BA

IIAGEINWEEKS

15

10

IIAGEINWEEKS

15

Fig.11.3.—Occurrenceofbarkingduringthedominancetestsatdifferentages.Upper:averagenumberofbarks.Lower:percentageofanimalsbarking.(Notethatthesetwocharacteristicsarenotdirectlyrelated.)


makehasadifferentqualityfromthatinotherbreeds.Thustherearethreedifferentaspectsofwhatlooksoffhandtobeasimplebehaviortrait.Oneisthethresholdofstimulation—veryhighinthebasenjiandverylowinthecockerspaniel.Asecondtraitisthetendencytobarkonlyasmallnumberoftimesratherthantobecomeexcitedandbarkcontinuouslyasdomanycockers.Themaximumnumberofbarksrecordedforacockerina10-minuteperiodwas907,ormorethan90aminute.Stillathirddifferenceisthetonequality,whichwe

TABLE11.5

TABLE11.5

PerCentofAnimalsBarkingperOpportunityComparedwithExpectedPercentage

didnotattempttoanalyze,astheequipmentnecessaryforproducingasoundspectrogramwasnotavailablewhenwestartedtheexperiment.

Inanalyzingtheeffectsofheredity,wefirstfindthattherearenoimportantdifferencesbetweenthesexeswithregardtothistypeofvocalization.Analyzingtheinheritanceofthetwotraitsisthereforereasonablysimple.TheFigenerationshowsalmostasmanyanimalsbarkingasdothecockerspaniels(Table11.5)butnotasmanyanimalsbarkingtoexcess(Table11.6;Fig.11.4).Thereisnogreatdifferencebetweenpuppiesbornofbasenjimothersandthosebornofcockers,sothatwecanruleoutthepossibilitythateithersex-linkedinheritanceorlearningbyexamplefromthemotherhasanygreatimportance.

TABLE11.6PerCentofAnimalsBarking19orFewerTimesat11Weeks

BreedorHybrid

Basenji

Cocker

F,

F,

Backcrosstococker..Backcrosstobasenji.

NumberTested

PerCent

95.218.451.353.018.862.9

BEHAVIORPATTERNS

277

Thislooksasifthetraitofbeingeasilystimulatedtobarkisinheritedasadominantone.Ifwenowcomparethepercentageofanimalswhichbarkedduringeachopportunitywiththepercentagecalculatedbyassuminginheritancethroughasingledominantgene,wefindareasonablycloseagreement,andinfactabetteragreementthanwithatwo-factortheory(Table11.5).Thisdoesnotmeanthat

20

10

BASENJI(42)

COCKERSPANIEL(49)(7animalsmorethan600)

F,(39)

F2(66)

cf"*"«■m.

BACKCROSSTOCOCKER(16)

BACKCROSSTOBASENJI(35)

100200300400500

Fig.11.4.—Distributionofbarkingtoexcessat11weeksofageinthepure

Fig.11.4.—Distributionofbarkingtoexcessat11weeksofageinthepurebreedsandhybrids.Thefigureshowsthenumberofanimalsproducingagivennumberofbarks.Notethatalmostallbasenjisbarkedlessthan10times.

thepossibilityofalargernumberofgenesiscompletelyruledout.Atesttocheckthiswouldrequireamuchmorecomplicatedexperimentandlargernumbersofanimals.Themostthatwecansayisthattheresultscouldbeexplainedinthisfashion.

Ifwenowlookattheinheritanceofthetendencytobarktoexcess(Fig.11.4),wefindadifferentsituation.TheFi'sarenowintermediatebetweenthetwoparentstrainsandtheF2'sverymuchliketheFi's.Thislookslikeacasewherethehybridsbetweentwostrains


haveageneticconstitutionclosetoathreshold.Consequently,eachanimalmaybepushedoverthethresholdorheldbelowitbyafewchanceenvironmentalfactors.Theresultsfromthebackcrossagreewiththishypothesis,sincethebackcrosstothebasenjisismorelikethebasenjisandthebackcrosstothecockersismorelikethecockers.Again,theresultscouldbeexplainedastheresultofasinglegene.

Insummary,theapparentlysimpletraitofbarklessnessturnsouttoinvolveatleastthreecharacteristics,ofwhichtwowereanalyzed.Thesetwoinvolvedifferentgeneticmechanisms;and,whiletheyaffecteachother,theydonotcombineinanysimplefashion.Obviously,adogwillnotbarktoexcessifitdoesnotbarkatall,andtheappearanceoftheformertraitisthusconditionalonthepresenceofthelatter.Consequently,theeffectsofthetwotraitstogethercannotberepresentedbysimpleaddition.Furthermore,thesetraitscanbestbedescribedintermsofprobabilitiesratherthanabsolutes.Givenaparticularsortofopportunity,suchasthecompetitionoverabone,thereisa20percentchancethatabasenjiwillbarkat11weeksofageanda68percentchancethatacockerwillbark.Theinheritanceofthistrait,likesomanyothers,illustratestheextremecomplexityofbehaviorwhichcanresultfromtheactionofasmallnumberofgeneticfactorsactingindifferentways.

Theresultsalsoraiseaninterestingquestionregardingthephysiologicalmechanismbehindthetraitofexcessivebarking.Someanimals,giventhestimulusofanotherpuppyinacompetitivesituation,willbarkafewtimesandthenstop.Otherscontinuetobark,becomingmoreandmoreexcitedandtaking

thenstop.Otherscontinuetobark,becomingmoreandmoreexcitedandtakingonanalmosthystericaltone.Itlooksasiftheymaybestimulatingthemselvesbytheirownbarking.Ifso,thiswouldaccountforthe"either-or"behaviorinbarking—eitherafewbarksoragreatmany.Excessivebarkingisnotonlyinterestingasagenetictraitbutalsoasitgiveshintsofthenatureofemotionalstimulation.

INHERITANCEOFDIFFERENCESINSEXUALBEHAVIOR

AllthemembersofthegenusCanishavesimilarpatternsofsexualbehavior,aswehaveshowninapreviouschapter.Oneofthepeculiaritiesoftheirbreedingcvcleisthefactthattheperiodofestrusorreceptivityinthefemaleisprecededbybleeding.Inwolvesandcoyotesthebleedingmaybeginquiteearlyintheyear,inJanuaryorFebruary,andtherearesomereportsofwolvesinwhichthisbeganinDecember.Actualmatingofwolvesusuallytakesplace

BEHAVIORPATTERNS279

inlateJanuaryorFebruaryandisnotrepeateduntilthefollowingyear.

Incontrast,thefemalesofmostbreedsofdomesticdogshaveestruscyclesatanyseasonoftheyearandapproximately6monthsapart.Thecycleisregulatedbyhormones.Afterpregnancyandalsoafteracycleinwhichnoeggsarefertilized,thecorpusluteumoftheovarycontinuestosecreteprogesteroneforseveralmonths,suppressinganyfurthercyclesaslongasitfunctions.Thelengthofthecycleisthereforeregulatedbythelengthoftimeduringwhichthecorpusluteumpersists.

Thebasenjiisdifferentfromotherdogbreedsinthatfemalescomeintoestrusataparticulartimeofyear,closetotheautumnalequinox,andshowonlyonecycleperyear.Theinheritanceofthistraitisparticularlyinterestingbecausewecanbepositivethatourparentstocksaregeneticallypureinthisrespect.Wehavenorecordsofcockersshowingseasonalcyclesandnorecordsofbasenjisshowing6-monthcycles.

However,whenwelookatindividualrecordsindetail,weseethatthereissomevariabilityinbothstocks.ThemodalmonthforthebasenjicycleisSeptember,andthevastmajorityofbasenjiheatcyclesbeginduringthelasttwoweeksofSeptemberandthefirstweekinOctober.Moreover,acertainnumberofcyclesbegininlateAugustandafewaslateasNovember.Thismeans,ofcourse,thattheintervalbetweencyclesisnotexactly12months.Thesamedogmaycome

theintervalbetweencyclesisnotexactly12months.Thesamedogmaycomeintoestrusearlyoneyearandlatethenext,sothatwehaverecordsofintervalsasshortas10monthsandaslongas14,withthegreatmajorityfallingbetween11and13.

Whenwelookatcockers,weseethatthe6-monthcycleisonlyanapproximation.Someindividualshavequiteregularcycles,comingintoheatatapproximatelythesametimeseachyear,asshowninFigure11.5.Othersaremorevariable.Theintervalmayrunanywherebetween3and11months,withthemodeatapproximately6months.Thismeansthattheshortestcyclesofthebasenjiscanoverlapsomeoftheexceptionallylongcyclesofthecockers.Thereisnoindication,however,thatthecockersshowanyremnantoftheannualspringcycleoftheirwolfancestors,orthatbasenjiseverruntwocycles6monthsapart.

Inordertostudytheinheritanceofthistrait,weretainedallthefemalehybridsuntiltheyhadgonethroughatleasttwocycles.AfewoftheFifemaleswhichwereparentsoftheF2Sweresaveduntiltheywereseveralyearsold,andwewerethusabletogetrecordsonmanyrepeatedcyclesfortheseindividuals.


Theactualrecordswereresultsofweeklyexaminations,atwhichtimeswelookedfortheonsetofbleedingandnoteditdown,ifpresent.Thedatesarethereforeonlyaccuratewithinaweek,sincebleedingmighthavebegunasmuchas6daysearlier.Therearecertainpossibilitiesoferrorinthataslightamountofbleedingcouldbeoverlooked.Inafewcasesthishappenedandtheanimalsbecamepregnant.Insuchcasesweestimatedtheonsetoftheestruscyclebycountingback63daysandadding1week.

46810

04I2C5)

0415(15)

I670(n)

I670(n)

468101672(10)

MONTH

Fig.11.5.—Monthinwhichbleedingbeganinfiverelatedcockerspaniels:mother(0415),doublegrandmother(0412),and3daughters.Numbersinparenthesesindicatenumbersofcyclesobservedineachanimal.Notethatsomeanimalswerehighlyvariable,butsome(1667and1672)ranfairlyregularcvclesat6-monthintervals.

OurresultsshowedthattheFifemalesweredifferentfrombothparentstocks.Manyofthemhadtwocyclesinthelatterhalfoftheyearintheperiodofdeclininglight.AfemalemightcomeintoheatinJulyandagaininSeptemberifshewasnotmatedandmadepregnant.Femalesmightalsocomeintoheatinthespring,andinthoseanimalswhichwerekeptseveralyears,ourrecordsshowtwopeaks,inFebruaryandAugust.Sincethevmightskipthespringperiod,however,theFi'swerecapableofhavingevclesquitefarapartaswellasquiteclosetogether.Inshort,theFihybridsare

BEHAVIORPATTERNS

281

morevariablethaneitheroftheparentstrains,althoughfromthestandpointofgenetictheorytheyshouldallbealike.Theexplanationisobvious.TheFi'shaveinheritedthebasenjitendencytorespondtodeclininglight,buttheyhavealsoinheritedthecockertendencytoruncyclesevery6months.Theinteractionofboththesetraitsproducesahighdegreeofvariability.

Whenwelookattheotherhybrids,weseethattheF2isquite

BASENJI

BXCOCKER

246t10•1214

MONTHS

Fig.11.6.—Intervalsbetweenfirsttwoestrusperiods(inmonths).NoteindicationsofsegregationinthebackcrosstothebasenjiandwidevariationintheFvFi'salsoshowedcyclesofintermediatelengthinlaterperiods.

similarinvariabilitytotheFi,sothatacomparisonofthesetwogenerationsgivesusnocluestotheinheritanceofthetrait.Thebackcrosses,however,appeartoshowMendeliansegregation.Aboutone-halfthebasenjibackcrossesshowlongcycleslikeabasenjiandaboutone-halfshowshortercycleswhicharetypicaloftheFihybrids.Thebackcrossestothecockers,ontheotherhand,arequitesimilartocockers.Wecanthenformulateahypothesisthatthebasenjitypeofcycleisinheritedasasingle-factorrecessive,withthe


heterozygotesshowingthepeculiartypeofinteractiondescribedabove.SinceveryfewoftheFi'shavecyclesaslongas11months,wecantentativelyclassifyallindividualshavingcyclesof11monthsorlongerasbasenjitypesandthentestourhypothesisinthebackcrossandF2generations.Inthebackcrosstothebasenjisthetheoreticalratiomatchestheobservedratioalmostperfectly.IntheF2generationtherearenotasmanyanimalswithlongcyclesaswemightexpect,whichbringsupthepossibilitythattherecouldbetwofactorsinsteadof

expect,whichbringsupthepossibilitythattherecouldbetwofactorsinsteadofone.However,thetwo-factorhypothesisfitstheback-crossquitepoorly(theprobabilityofgreaterdeviationfromtheexpectedratioisonlytwoinonehundred).Bycontrast,theone-factortheoryfitstheF>considerablybetter,withaprobabilityof.08(Scott,Fuller,andKing,1959).

Wemaythereforeconcludethatthemostprobablegeneticexplanationoftheobservedfactsisone-factorinheritance.Thepossibilityoftwo-factorinheritanceisnotdefinitelyexcludedhowever,sincewedidnotdothecrucialexperimentforaone-factorhypothesis,i.e.,repeatedbackcrossestotherecessive.

Thereareseveralimportantconclusionsthatcanbedrawnfromthesedata.Thefirstisthatwehaveaclear-cutcaseofahighlyvariableFiwhichcannotbeexplainedbypossibleheterozygosisoftheparents.TheexplanationthereforeliesinthephysiologyofgeneactionratherthaninMendeliansegregation.Second,wehavesomeclearindicationsastowhatthisphysiologycouldbe,i.e.,onememberofagenepairfromthebasenjicausingaresponsivenesstolightchangesandtheothermemberfromthecockerspanielproducingatendencytorun6-monthcyclesinadditiontothefirsteffect,withbothmembersofthepairinteractingwitheachothertoproducethefinaleffect.Itshouldalsobenotedthatthisisquiteadifferentkindofexplanationfromthethresholdhypothesis,whichexplainsasimilarvariabilitvoftheFiscoresonplavfulaggressiveness.Finally,thiscaseshowshowthesimplestsortofMendelianinheritance,thatinvolvedinonepairofgenes,canproduceahighlycomplexandvariableresultonbehaviorbyactinguponphysiologicalprocesseswhichaffectbehaviormoredirectly.Aswehaveseeninalltheabovecases,suchcomplexityseemstobecharacteristicofgeneticeffectsuponbehavior.SuperimposeduponthealmostinfinitevariabilitypossiblefromMendelianmechanisms,wehaveastillgreatervariabilitymadepossiblethroughthephysiologicaleffectsofgenes.Ofcourse,thismakesithighlyunlikelythatanytwoindividualsinageneticallyvariablepopulationwilleverbehaveexactlyalike,eveniftheyareplacedinidenticalenvironments.Italsomakestheexact

BEHAVIORPATTERNS283

geneticanalysisofanysortofhighlycomplexbehavior,suchassuccessinproblem-solvingsituations,almostimpossiblebypresentmethods.

EFFECTSOFTHEMATERNALENVIRONMENT

InalmosteverytestthatwedidtherewassomedifferencebetweenthereciprocalcrossesintheFi's,andthesedifferenceswereperpetuatedintheF2inmanycases.Therearethreedifferentwaysinwhichsuchdifferencescouldbebroughtabout.

Sex-linkedinheritance.—Ifatraitisproducedbyasex-linkedrecessivegene,thistraitshouldappearinallthemalesandnoneofthefemalesbornfromrecessivemothersmatedtodominantfathers.Inthereciprocalcross,theFi'sfromrecessivefathersshouldallbeliketheirdominantmothers.Ifsex-linkedinheritanceispresent,itcanbeeasilyrecognizedbythefactthatthereisanimportantdifferencebetweenmalesandfemalesinoneoftheFipopulationsbutnotinthatfromthereciprocalcross.

Noindicationofthissortwasfoundinanyofthe40variablesselectedfordetailedstudy.Thelackofanycaseofsex-linkedinheritanceinbehaviorcharacteristicsinasampleofthissizeshouldnotsurpriseus,sincethereare39pairsofchromosomesinthedogandonlyoneoftheseincludesthesexchromosomes.Assumingthatthereareequalnumbersofgenesonallchromosomes,averylargenumberofgeneswouldhavetobestudiedtofindevenonecaseofsex-linkedinheritance.Thelargenumberofsex-linkedgeneswhichhavebeenfoundinmanisprobablyrelatedtothefactthatthistypeofinheritanceisveryeasytorecognizeinfamilypedigreescomparedwiththepatternofinheritanceproducedbyarecessivegenefromanotherchromosome.

Accidentalselectionofdifferentstrains.—Thereiseveryindicationthatagreatdealofindividualandstrainvariabilityexistswithinthepurebreedsofdogs,andinselectingthe4pairsofparentsforeachcrosswemayhaveaccidentallyincludedtwodifferentsortsofanimals.Withsuchaccidents,wewouldtheoreticallyexpectthattheresultingdifferencebetweenthetwoFicrossesmighteitherbeinthesamedirectionasthedifferencebetweentheparentstrainsorintheoppositedirection,dependingpurelyonchance.Thelatterseemstohavebeenthecasewithregardtophysicalsize.Bychance,weincludedanunusuallylargebasenjimaleandoneortwolargecockerspanielfemalesamongtheparentsintheBCScross.Theresultwasthattheoffspringborntotheseanimalswere,ontheaverage,larger


thanthoseborntothebasenjimothers.Thus,thedifferencebetweentheFi'sisintheoppositedirectionfromthatoftheparents.Wewouldtheoreticallyexpect

theoppositedirectionfromthatoftheparents.WewouldtheoreticallyexpectthatsuchadifferencewouldbeperpetuatedintotheF2generation,butthisisnottrue(Table11.8).ThattheF2'sarealikeisaccountedforbythefactthattheexcessivelylargeFianimalswerenotchosenasparents.

Ifchancehadworkedintheoppositedirection,wemighthaveselectedparentsfortheFigenerationwhosegeneswouldproduceadifferenceinthesamedirectionasthatbetweentheoriginalpurestrains.Inthiscase,accidentalselectionasacauseofthedifferencecouldnoteasilybedistinguishedfromthematernalenvironment.

Effectsofmaternalenvironment.—Ifamotherinfluencesthebehaviorofheroffspring,eitherbysomeprenatalenvironmentaleffectorbyapostnataleffectinvolvinglearningfromthemother,wewouldexpectthattheeffectwouldbeusuallytomaketheoffspringmorelikethemother.Aspointedoutabove,thereisnowayofdistinguishingthiseffectfromthatofstraindifferencesinanyindividualcase,butwecanmakeatestoftheover-allexperiment.Ifselectionofstraindifferencesweretheimportantfactor,wewouldexpectthatinhalfoftheteststhedifferencesbetweentheFi'swouldbeinthesamedirectionasthatbetweentheirparentsandintheotherhalfdifferenceswouldbeintheoppositedirection.Asitturnedout,12outof40testsshowedunlikedifferences,while28outof40showedlikedifferences.Thus,wehaveevidencethatsomesortofmaternaleffectshaveplayedanimportantpartinbehavior.

Ifsucheffectsdoexist,theyshouldbecontinuedintotheF2generationinanundilutedform.Examiningtheactualdata(Table11.7),wefindthatthereisonecaseinwhichthedifferencesintheFiandF2generationsareverynearlyaslargeasthosebetweentheparents.Thisistheattractionscoreonthehandlingtestat13and15weeksofage,whichischieflybasedonthenumberoftimeswhichadogfollowsorcomestowardanindividual.Therewouldbeampleopportunityforpuppiestolearnsuchbehaviorfromtheirmothers,asexperimentersandcaretakersenteredtheirpensweekafterweek.

Anothercasewithalessobviousexplanationisthevocalizationandtimescoresof6-week-oldpuppieswhenconfrontedwithabarrierbetweenthemandtheirfood.InthesecorrelatedscoresthedifferencesareinthesamedirectioninbothFiandF2andseemtobelittlereducedinthelattergeneration.OthertestsinwhichthereisaconsistentmaternaleffectpersistingtotheF2generation,arethetrailingtest,thetimescoreinthespatial-orientationtest,andthespeedscoreinthedelayed-responsetest.Inthefirsttwo,thediffer-

BEHAVIORPATTERNS

285

TABLE11.7

TestsInvolvingPersistentDifferencesbetweenMaternalLines(StanineScores)

Test

Attraction

Noises,barriertest

Trailing

Spatialorientation,time

Motivation,speed

Reactivity,investigation

Reactivity,escape

Heartrate,adult

Heartrate,bell

Leashcontrol

encebetweentheF2'sisconsiderablyreduced,indicatingthelossoftheeffectandprobablecomplicationsbygeneticfactors.

Severalscoresonthereactivitytestsgiveindicationsofimportantmaternaleffects,particularlythescoresoninvestigativebehaviorandattemptsatactive

effects,particularlythescoresoninvestigativebehaviorandattemptsatactiveescape.Likewise,theadultheartratescoreshowsaveryimportanteffect,asdoesoneoftheotherheartratescores.Finally,theleash-controltest,involvingthetendencytobiteandjerkaleash,showsalargeandconsistenteffectwhichisverylittlereducedinthesecondgeneration.

Inconclusion,threeofthetests,theattraction,heartrate,andleashcontrol,giveevidenceofunusuallyimportantandpersistenteffectsrunningthroughthematernalline.Thereisanobviousexplanationofhowthesecouldbeproducedintheattractionscore,andeventheheartratemayrepresentalearnedemotionalreactiontohandling.Theeffectofleashcontrolismoredifficulttoexplaininsuchtermsand,asindicatedabove,mayactuallybeanaccidentalresultofstrainselection(seechap.12).

RESULTSOFANALYSISOFOTHERTESTS

Performancetests.—Someoftheperformancetestswhichwedevisedweresodifficultthatalargenumberofpuppiesfailedtosolvethem.Thisautomaticallyforcedthedataintoatwo-categorydistributionoffailuresandsuccesses,andthisinturnsuggestedthepossibilityofanalysisbythemethodsofqualitativeinheritance.

Inthebarriertestgivenat6weeksofage,basenjisshowmuchmoreabilitytosolvetheproblemwithoutmistakesthandocockerspaniels.Likewise,inthemanipulationtests,thebasenjisshowcomparativelyfewfailuresandcockerspanielsshowalargenumber.

a.:"i-i^-±.Z---Z-n

However,there:rnplepatternofMendelianinheritanceap-

parentinthehybridpopulations.Thereasonsforthisarefairlyobviousinthemanipulation:meanimalsstartoffwellonthe

simp].andfailasthetestagetharder,prîse::'

alackofcapac:::anlmaUdopoorlyattheoutsetan:

a:7esctwoverydifferenttypesofreactionstothesituationprobablyinvolvequitedifferenthereditarvmechanisms,andtheycertainlyleadtocomplexres

Mostoftheotherperformancetestsweresodesignedthatall

Mostoftheotherperformancetestsweresodesignedthatall

alswouldsucceedandobtainsomesortofscoreonacontinuousscale.TheseresultsfMycouldbeanalyzedbythemethodsof

quantitativeinheritance,buthereaâinnoneofthedenceofanysimplernofMendelianinheritancesuch

forthistypeofanalysis.Therearestillothermethodswhichcanbeusedtoanalyzesuchdata,namelythecalculationoftheamountsofvarianceduetobreeddifferences,andtheresultsarepre5anotneichapter.

;—Thesizenaretheoretically

welladaptedtoanalysisbythe:sofquantitativeinheritance.

However,eventhispartofthimentiscomplicated,firstbythe

factofstraindifferencesreferredtoaboveandsecondbyhybridvigor.BoththeF7sandFi'sareontheaverageverynearlyasbigas

ops,thelargerofthetwoparents.TheincreasedbodysizeoftheF:canbeattributedtohybridvigor,andtheFa'sareinturnaffectedbvthissamehvbridviôrinthattheirFimothershadunusuallyabundantmilksuppliesandgavethemexcellentcare.Xe

bslthebackcrossandF.generationsdoshowgreatervariation

thantheF:'s.asmightbeexpectedfromMendeliansegregation

TableUS.Calculationsbaseduponthisgiveapproximateesti-

TABLE11.8

DBTMBrnaxofAdultWeightMeasurement5Coc::sHybbids(S:si5=9kg.)

BEHAVIORPATTERNS

287

matesofonegeneaccountingforthedifferencebetweenbasenjisandcockerspaniels.

spaniels.

Theheartrateofyoungpuppiesalsoshowsacontinuousdistributionandevidenceofincreasedvariationinthesegregatingpopulations(Table11.9).Thegeneralpatternofinheritancelookslikeoneofnodominanceexceptthatthebackcrossgenerationsarealmostexactlyliketheirmaternalparents.AnalysisoftheF2datagivesafigureoflessthanonegene;butitispossiblethatifthevariancewereadjustedinvariousways,theresultwouldbemoreclear-cut.Atanyrate,theevidenceindicatesthatnotmorethantheonegeneisinvolved.

TABLE11.9

DistributionofAverageHeartRates,11-16Weeks,ConvertedtoStanines

THEDEVELOPMENTANDDIFFERENTIATIONOFBEHAVIOR

Aswesawinourstudyofthedevelopmentofthetraitsofbarkingandbarklessness,themaximumdifferencesinthattestsituationappearedat11weeksofage.At5weeksthebasenjisandcockersweretoomuchaliketomakeageneticanalysispossible,andby15weeksbothbreedshadbeguntobarksolittlethatgeneticanalysiswasagainimpossible.Thefollowingexamplesgiveanevenmoreclear-cutcaseofthedevelopmentofdifferencesinbehavior.

Inheritanceofthetendencytobequietwhileweighed.—Onceperweekeachpuppywasplacedonaplatformscaleforoneminuteandgivenmildforcedtraininginbeingquiet,asdescribedinchapter9.Figure11.7showsthedevelopmentofthebehaviorofbeingcompletelyinactivefor1minute.By11weeksofageapproximately70percentofthecockerspanielskeepquiet,andthisproportionclimbsslowlythereafter.Bythesameagethepercentageofbasenjisreaches


approximately20percentandstaysatthesamelevel.Wecanthereforesaythatthebehaviorofthetwobreedshasbecomedifferentiated,althoughsomeoverlapbetweenindividualsstillremains.

Wecannowanalyzetheinheritanceofthetraitatthetimewhenmaximumdifferencesappear,usingmethodsforqualitativeinheritance.Inordertogiveasomewhatmoreaccurateestimate,wecanaveragethescoresat14,15,and16weeksofage.Theaccuracycanalsobeimprovedbyincludingonlythose

weeksofage.Theaccuracycanalsobeimprovedbyincludingonlythosecockersandbasenjiswhicharemostcloselyrelatedtotheparentsinthecross;itturnsoutthattheyaresomewhatmoredifferentfromeachotherthanarethetwo

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fortheone-minuteperiodwhileweighed,inthecockerandbasenjibreeds.

generalpopulationsofeachbreed.Analyzingthisresult,wegetfigureswhichapproximatethosewhichwewouldexpectfromtwo-factorinheritance,withthecockerspanieltendencybeingrecessive.Thefiguresdepartwidelyfromwhatmightbeexpectedifasinglefactorwasinvolved.

Theinheritanceofposturalresponses.—Aspartofthesametest,theinitialpostureofthepuppyasitwasplacedonthescalewasrecorded.Therearefourpossiblebehaviorpatterns:lyingflat,crouchingwiththelegsbentandheaddown,sitting,andstanding.

Inthecockers,behavioronthescaleisrelatedtothetendencyofthebreedtolieflatwhenthreatened,whichgoesbacktotheirmedievaluseinsettingbirdsforthenet.As"setters"theyweresupposedtolieflatupontheground.However,thetopofthescalewas

BEHAVIORPATTERNS

289

only10.5X12inchessquare,notanidealplaceforlyingflat,especiallyastheanimalsgrewolder,sothatthefavoritepositionofthecockerspanielpuppieswasusuallysitting.

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lyingflatonthescaleandcontinuetodothisthroughtheneonatalperiod.Duringthetransitionperiodtheybegintoadoptothertypesofposture.At3weeksofagebothbasenjisandcockershaveatendencytocrouchinsteadoftoliedown,butsomeofthemarebe-

ginningtositaswell.Bv5weeksofagethemostcommonpostureiscrouching,whilethefrequencyofsittinghasdeclined.Crouchingreachesitspeakat5weeksinbasenjisbutnotuntil7weeksincockersandthereafterdeclinesinbothbreedswithverylittledifferencebetweenthem.Ascrouchingdisappearsitisreplacedbystandinginthebasenjisandbysittinginthecockers,sothatat16weeksofageabout70percentofthecockersaresittingandnearly90percentofthebasenjisarestanding.Thecurveforsittinginthecockersisstillrising,indicatingthatthebehaviorhasnotbeenfullydifferentiatedinthisbreed.However,inbothbreedsthepercentageofanimalsstandingisprettywellstabilized.

Analyzingtheratiosbasedonscoresat14-16weeks,whenthetendencytostandismostcompletelydifferentiatedbetweenthetwobreeds,wefindthattheratiosfitwhatmightbeexpectedifthereweretwogenesinvolved,thoseforthecockerspanielbeingdominant.Thefitisnotasgoodasitwasinthetraitofbeingquiet,butthismayresultfromthefactthatbodysizehassomeeffectonthepostureonthescales.Inbothcockersandbasenjis,thereareconsistentlymorefemalesstandingthanmales,probablybecausetheirsmallersizemakesiteasiertodoso.Likewise,theF2animalssometimesbecameunusuallylargeduetotheexcellentnutritionprovidedbytheirFimothers,andfeweroftheF^'stookthestandingposturethanmighthavebeenexpectedfromasimplegenetictheory.

Oneinterestingresultoftheexperimentisthatthebehaviorofthecockerspaniels,whichlookslikeasimplebehaviorpatternoflyingquietlyonthescale,isactuallymorecomplex.Beingquietisinheritedasarecessivetrait,theFi'sbeingactivelikebasenjis.Thetendencytoadoptsomeotherposturethanstanding,ontheotherhand,isinheritedasadominanttrait,withtheFi'sbeingliketheircockerparents.Weareobviouslydealingwithtwodifferenttraits,andthisisbackedupbythefactthatthereisnocorrelationbetweenthemintheF2puppies,inwhichbothtraitscanappear.Sinceourresultsindicatethatatleasttwogenesareinvolvedineachoneofthesetraits,thegeneticmechanismisquitecomplex.ThechanceofgettingananimalgeneticallyidenticaltooneoftheoriginalpurebreedsintheF2generationis(0.25)4,or1in256.Sincewe

theoriginalpurebreedsintheF2generationis(0.25)4,or1in256.Sinceweonlyhad74animalsinthisgeneration,itisquitelikelythatnoneofthemwereexactlyliketheoriginalpurebreedinrespecttothistrait.

Theotherinterestingresultofthisexperimentisthealmostdiagrammaticillustrationoftheprocessofdifferentiationofbehaviorresultingfrommaturationandtraining.Thegraphsshowallpuppies


startingoutverymuchthesameandgraduallybecomingmoreandmoredifferentuntilfinallytheyshowthebehaviorwhichweordinarilythinkofasbeingcharacteristicofthebreed.

SUMMARY

Theseanalysesoftheinheritanceofsimplebehaviortraitsshowthatinheritancecanbeexplainedinmanycasesonthebasisofoneortwogenes.Thisissomewhatsurprising,aswewouldexpectthatanythingascomplexasbehaviorwouldbeaffectedbymanygenes.Weshouldremember,however,thattheseparticulardifferencesinbehaviorwereproducedbyartificialselectionandthattheeffectofageneonacharacterasvariableasbehaviorcouldprobablynotberecognizedunlessitwasquitealargeeffect.Abreederchoosingbetweentwodogsusuallycannotdistinguishbetweenbehavioraldifferencesproducedbyheredityandthoseproducedbytrainingandotherenvironmentalexperiences.Unlessageneproducesarelativelymajorresult,itislikelytopassunnoticedandbelost.Minormodifyingfactorsseemtohavetheirchiefimportanceincontributingtoindividualandstraindifferenceswithinabreed.

Weshouldalsorememberthatthebehaviorpatternis,inonesense,anaturalunitofbehavior.Allselection,whetherartificialornatural,isdoneonthebasisofeffect,andthemodificationofbehaviorpatternshavingspecificfunctionsisconsequentlythemostdirectwayinwhichselectioncanaffectbehavior.Ofallthemeasuresofdifferenceinbehavior,thoseinvolvingsimplebehaviorpatternsaremostlikelytohavedirectandreasonablysimplegeneticexplanations.

Whilethepossibilityofsingle-factorinheritanceisthusareasonableone,thisconclusioncannotbefinalintheabsenceofacriticaltestforsingle-factorinheritance,namelv,asecondbackcross.Confirmationwillthereforehavetoawaitfurtherexperimentation.Assumingthatthesingle-factorexplanationisavalidone,weshouldpointoutthatitworksbestwhenappliedtocasesinwhich

validone,weshouldpointoutthatitworksbestwhenappliedtocasesinwhichsimplebehaviorpatternsareeitherpresentorabsent.Thisisconsistentwiththetheoryofathresholdofresponsetostimulationmodifiedbygeneaction.

Ontheotherhand,thetheoryofathresholdmodifiedbyasinglegene,orIn-theadditiveactionofseveralgenes,doesnotapplytoanycaseofathresholdofsuccessfuladaptationtoacomplexproblem-solvingsituation.Heretheunderlvingprocessesofgeneaction

BEHAVIORPATTERNS293

appeartobemuchmoreintricate.Thereisevidenceinthecaseoftheinheritanceoftheannualbreedingcyclethattheactionofevenasmallnumberofgenescanproduceextraordinarilycomplexeffectsthroughinteractiononaphysiologicallevel.Beyondthis,thecombinationoftwosimplyinheritedpatternsofbehaviormultipliesthenumberofpossiblegeneticcombinationsforthewhole.Evenasmallnumberofgenescanthusproduceanenormousamountofvariabilityinapopulation.

Whilebothsimplequalitativeandquantitativeinheritancearesometimesfoundinrelationtosimplepatternsofbehavior,thecombinationofthesepatternsintocomplexadaptivepatternsthroughlearningandproblemsolvinginevitablyresultsinanextremelycomplexgeneticsituation.Themultiple-factortheoryofgeneticeffectsofbehavioriscorrectinthesensethateachbehaviorpatternappearstobeaffectedbyadifferentsetofgenes.Ontheotherhand,extremelycomplexeffectscanbeexplainedbyasmallnumberofgenes,sothatthegeneticmechanismsareprobablybasedonafinite,andpossiblyrelativelvsmall,numberofmutations.

Wealsofindthatbehaviorhastobedeveloped:thatitonlyappearsatparticulartimesindevelopmentandunderparticularenvironmentalconditions.Theinheritanceofasimplephysicaltraitlikelongandshorthairseemstocontradictthisfinding,butthecontradictionisonlyanapparentone.Eveninthiscasewefindthatthetraitundergoesdevelopmentbecausepuppiesatbirthhavehairwhichismuchthesamelength,andbeforebirththereisatimewhenthefetushasnohairatall,shortorlong.Thisemphasizestheimportantfactthatgeneticcharacteristicsorphenotypesarenotinastrictsenseinherited,butalwaysdevelopedundertheinfluenceofgeneticandenvironmentalfactors.Thebigdifferencebetweenbehaviorandtheanatomicalcharacteristicsusuallystudiedbygeneticistsisthatthegreatbulkofbehavioraldevelopmentoccursafterbirthratherthanbeforeandthatbehaviorcontinuestodevelopanddifferentiate

ratherthanbeforeandthatbehaviorcontinuestodevelopanddifferentiatethroughoutlife.

Inthischapterwehaveindicatedtwodifficultiesindealingwiththedata.Oneoftheseisthatmostofthemathematicalmethodsusedsofarassumethattheparentpopulationsarepurebreeding,althoughwehaveeveryreasontobelievethatthedogbreedsaregeneticallyvariableinmanyrespects.Theotherdifficultyisthatofapplyingquantitativemethodstocasesinvolvingcomplexinteraction,whetheronthegenetic,physiological,orbehaviorallevels.Inthenextchapterweshallattempttodealwiththesedifficultiesby


theuseofquantitativemethodswhichdonotdependupontheassumptionofhomozygosity,andwewillalsoseeifthesespecializedmethodsapplytotheinheritanceofcomplexpatternsofbehaviorwhereitishighlylikelythatmanygeneticfactorsareinvolved,andhencethatsomeofthemareheterozygous.

BEHAVIORINHYBRIDS:COMPLEXBEHAVIOR

Inpreviouschapterswehavedemonstratedthatbreedsofdogsdiffersignificantlyintheirscoresonalargenumberofbehavioraltests.Onoccasion,therelativeimportanceofthebreeddifferenceshasbeenexpressedasanintraclasscorrelation,definedastheproportionoftotalvarianceascribedtobreeds.Correlationsof.2to.5werecommon;20outof34variablesanalyzedinTable14.3fallwithinthisrange.Onsomemeasuresthedegreeofoverlapbetweenthebreedswasconsiderable,butexampleswerealsofoundofalmostcompleteseparationofscoresinsomebreeds.Inthischapterweshallattempttoextendthissortofanalysistohybrids,andparticularlytocasesofcomplexbehaviorinwhichnosimplepatternofinheritanceisapparent.

Thegeneralbiologicalsignificanceofestimatesofgeneticeffectsderivedfrombreedcomparisonsislimitedbythepeculiaritiesofthematingsystembywhichbreedsareformedandmaintained.Apurebreedisfarfrombeingahomogeneousgroup.Thecockerspaniels,beagles,andShetlandsheepdogsshowedsegregationatcoatcolorloci,thebeaglesforhairlength,andallbreedsshowedheterogeneityinbloodtype(CohenandFuller,1953).Thus,tousebetween-breedvarianceasameasureoftheeffectsofheredityandwithin-breedvarianceasameasureofenvironmentaleffectsissimplificationwhichcouldleadtoerror.Ifsomeofthebehavioralvariationbetweenmembersofthesamebreedisgenetic,theintraclasscorrelationtendstounderestimatetheimportance

breedisgenetic,theintraclasscorrelationtendstounderestimatetheimportanceofheredity.Ontheotherhand,fixationwithinabreedofspecialcombinationsofgenescouldproducepeculiaritiesofbehavior.Suchcombinations,maintainedbyrestrictingmatingswithinabreed,wouldbegeneticinthebroadsense.Inarandommatingpopulation,thesecombinationswouldbe

295


brokenupbecauseoftheindependentassortmentofchromosomesandthepeculiaritiesofbehaviorassociatedwiththemwouldberare.Ifthisargumentholds,breeddifferencesmightprovideanexaggeratedestimateoftheimportanceofheredityforbehavioralvariationinapopulationwithamoreopenbreedingsystem.

METHODS

Breedingplan—geneticimplications.—Inordertoextendourinformationonthetransmissionofbehavioralcharactersthroughgenes,crossesweremadebetweenbasenjisandcockerspaniels.Thesetwobreedswerechosenforthehybridizationstudybecausetheyshowedmarkedphenotypicdifferencesonmanytestsandwerealsoaboutasremotelyrelatedasanytwobreedscouldbe.ItwillberecalledthatfourofourfivepurebreedsoriginatedintheBritishIslesandthatthebasenjisisofAfricandescent.Historicalevidenceindicatesthattherehasbeennogeneticinterchangebetweenthebasenjisandthecockerspanielsforatleastseveralcenturiesandpossiblyforthousandsofyears.Wewerealsoawareofconditionswhichmadethesetwobreedslessthanidealforageneticexperiment.Preferablythestocksemployedasparentsforacrossshouldbepure-breedinginastrictgeneticsense,atleastforthelociofinterest.Itisunlikelythatthisconditionwasmetinourbreedsexceptpossiblyforlocicontrollingbarklessnessandanannualbreedingcycle,butitisalsotruethatonmanyphenotypicmeasuresthedegreeofoverlapbetweenthebasenjisandcockerswasverysmall.Anotherdifficultyarosefromtheneedtobreedfromasmallnumberofparentsbecauseofkennelspacelimitations.Inahighlyinbredstockoneparentisgeneticallyequivalenttoanyotherofthesamestock,butinavariablepopulationthechoiceofparentsintroducesasamplingerror.SamplingerrorwaspossiblyresponsibleforsomeofthedifferencesfoundbetweenreciprocalFicrosses,thoughanalternativeexplanationinvolvingmaternaleffectshasnotbeenexcluded.

Asdescribedinchapter1,thebasenji-cockerspanielcrosswasessentiallyanordinaryMendeliancrosswithcertainmodificationsmadenecessarybythenatureofouranimals.ReciprocalbasenjiXcockermatingsweremadetoproducetwoFi's,eachofwhichwasbredinterseandbrothertosistertoproduceanF2population.Ideally,backcrossestotheparentalstrainswouldhavebeenmadeinreciprocalfashion,butlimitationsofspaceandtimeledustobreedinonlyonedirection,Fimalestoabasenjiorcockerdam.This

COMPLEXBEHAVIOR297

crossenabledustocompareoffspringofpurebreddamsbyFiandpurebredsires.

Sincethepuppieshadnophysicalorsocialcontactwiththeirsires,anydifferencebetweentheCSBFiandtheCSBXBbackcrossorbetweentheBCSFiandtheBCSXCSbackcross(seeFig.1.1)canbeattributedtothegeneticcontributionsofthesires.TheplanalsoallowedfortwocomparisonsbetweenbackcrossandF2groupswithcommonsires(Fi)butdifferentdams(Fiorpurebred).WefoundthattheFifemalesprovidedbettercarethaneithertypeofpurebred,thisbeingreflectedinlowerinfantmortality.Furthermore,offspringwereassociatedwiththeirdamsfor10weeks,offeringampleopportunityforlearningandimitation.Thus,thefindingofanydifferencebetweenFa'sandthebackcrossesfromthesamesirecanreasonablybeascribedinparttonon-genetictransmissionfromdamstooffspring.

Analysisbygroups.—Thedatafromthehybridsweretreatedintwoways—bygroupandbymating.ThegeneralprocedureisavailableinvarioussourcessuchasWright(1952)andFalconer(1960).Intheanalysisbygroup,weprovisionallyassumedthatbasenjisandcockerspanielswerepurebreedingforthemajorlociproducingbehavioraldifferencesbetweenthesestrains.Basenji,cockerspaniel,andFihybridgroupswereconsideredgeneticallyhomogeneousandallsiresordamswithinagroupasgeneticallyequivalent.Furthermore,wepredictedthattheheterogeneousF2andbackcrossgroupswouldbemorevariablethanthehomogeneousparentalandFigroupssincegeneticvariationbetweenmembersofthesegroupswouldbesuperimposeduponenvironmentalvariation.Theseexpectationswerenotoftenrealized,andaconsiderationoftheoutcomeofspecificmatingswithoutrespecttothegroupclassificationoftheparentswasfrequentlymoreenlightening.Nevertheless,onmanymeasuresinwhichthespanielsandbasenjisdifferedsharply,wefoundthatthemeansofthehybridgroupswerearrangedinanorderlyfashioncorrespondingtothegenetic

groupswerearrangedinanorderlyfashioncorrespondingtothegeneticcontributionoftheoriginalpurebreeds.Hadtheoriginalstocksbeenmorenearlyiso-genous,theresultswouldhaveprobablybeenevenmoreconclusive.

Analysisbymatings.—Inthistypeofanalysis,itisnotnecessarytoassumethattheparentstockswerehomozygous.Onthecontrary,wecantreatthedataasthoughtheparentscamefromamixedpopulation.Twomethodswereusedintheanalysisofoutcomesofspecificmatings.Regressionsbetweenthemean(d)ofoffspringfromamatingandthephenotypicscoresoftheirsire(s),dam(d),andmidparentoraverageofsireanddam(mp)were


computed.AregressionequationoftheformXj=a+bXPshowstherelationshipbetweentheaverageoftheoffspringofamating(Xz)andsomescoreoftheparents(Xp).Theconstantaallowsforthefactthattheoffspringmayaveragehigherorlowerthantheparents.Theconstantb,regressioncoefficient,hasgeneticsignificance(Falconer,1960).Forexample,theregressioncoefficientbb.mpisadirectestimateofheritability(h2);bz.aandbs.sareestimatesofh2/2.Sincetheonlyconnectionbetweenthesiresandtheiroffspringisthecontributionofgenes,2bs.sisordinarilythemostdependableestimateofh2.Insomecircumstances,however,wefoundthatoursiresweretoouniforminbehaviortoprovideagoodestimate;forsometestsscoresofallparentswerenotavailableandparent-offspringcorrelationwereunobtainable.

Analysisofvariance.—Asecondmethodofutilizingdatafromspecificmatingswasbyanalysisofvariance,whichenabledustoevaluatethegeneticcontributionofindividualsiresanddams,theimportanceofenvironmentalfactorsoperatingondifferentlittersofthesameparentage,andtosomedegreethevariationbetweenthegeneticcontributionsofparentsclassifiedinthesamegroup.Thedetailsoftheprocedureandinterpretationaredescribedlaterinthischapterinconnectionwiththefightingscoresinleashtraining.

Weshalldealwiththescoresofhybridsonagroupoftestsadministeredbetween4and12monthsofage.Allofthesetestshavebeendescribedinpreviouschaptersandprovideawidesampleofkindsoftestsandgeneticresults.Someofthemwereinitiatedsomewhatlaterthanothersintheprogramandhencehavemorelimitednumbersintheparentstrains.Inthesecasestheuseofthelastdescribedmethodwasparticularlyapplicable.Analysesarereportedonthefollowingscores:leash-controlfighting,leash-controlvocalization,motivationspeed,obediencecompositescore,spatial-orientationerrors,andtotal

motivationspeed,obediencecompositescore,spatial-orientationerrors,andtotalreactivityscore.Additionalmeasuresfromthesetestsarereportedinlessdetail.Theorderofdiscussioncorrespondstothatinwhichthetestswereadministered.

TRAININGTOLEAD

Analysisl)\jgeneticgroups.—Theleash-trainingprocedureandtheresultswiththepurebreedshavebeendescribedinchapter9.Thebasenjisandcockerspanielsdifferedsignificantly,particularlyonthecategoryofdemeritwecalled"fightingtheleash."Astrainingproceededtheaveragetotaldemeritsfellprecipitouslyinallbreedsuntilby10daysmostsubjectswerewalkingwellontheleash,

COMPLEXBEHAVIOR

299

thoughbasenjiswerestillchargedwithmoredemeritsthancockers.Whenoneusesthetotaldemeritscoreover10daysasameasureofperformance,allthehybridgroupsareintermediatetotheparentalstocksandthereisnosignificantdifferentiationbetweenthem(Table12.1).Thevariances(V)oftheF2andbackcrossgenerationsaresomewhathigherthanthoseoftheparentsandtheFi's.Esti-

TABLE12.1Leash-TrainingDemerits(Stanines)ofHybrids

matingtheheritability(hr)ofthetotaldemeritscorebytheformula

h2=

VF2

V

P2

andusingpooledestimatesfromthetwoFi's,oneobtains

Thisvalueshouldbeconsideredanapproximation,however,sincetheassumptionsofhomogeneityinvolvedinthegroupmethodhavenotbeenfullymet.Furthermore,thetotaldemeritscoreisobtainedbyaddingtogethertheoccurrencesofverydifferentformsofbehaviorwhichmayhavequitedifferent

occurrencesofverydifferentformsofbehaviorwhichmayhavequitedifferentdegreesofhereditarydetermination.

Amorefruitfulattackistoconsidertheperformanceofthehybridsandtheparentalstockswithrespecttotheindividualmeasurementswhichmadeupthedemeritscore.ThesefiguresarepresentedinFigure12.1.Comparisonofthefiguresimmediatelydemonstratesthattheroleofheredityindeterminingthetypeofdemeritsdiffersgreatlyforthetests.Theparentstrainsdifferedconsiderablyinfighting(F)andposition(F)demerits,andthehybridsfellatintermediatepositions.Ifthebehaviorwereinheritedinasimpleadditivemanner,thehybridmeanswouldfallonthelinedrawnbetweentheparentalmeans,(seeBruell,1962).Thereis

:::

:-'.-r.z-'-z'n

indicationofamaternaleffect,sinceanimalsresembletheirmothersmorethantheirfathers.Neglectingthesexchromosomes,thegeneticcontributionofthesexesisequal,butthesixeshadnocontactwiththeiroffspringwhilethedamswerewiththemfor10week

Fig.12.1.—Meanscoresofhybridsonairesofleashtraining.Solid

Idenotegroupswithbasenjimothersorgrandmothers.Alinedrawn

throughacircleindicatesanF2group.Thedashedlinesbetweentheparental

meanswouldpassthroughthehybridmeansifthecharacterswereinherited

inasimpleadditivefashion.

Ontwomeasures,fightingtheleash(F)andposition(F),theparentalstocksaredistinctandthehybridsintermediate.Inbothscoresthehybridsresembletheirdamsorgranddamsmorethantheirsiresorgrandsires.Onthreemeasures,balksintheopen(B),atdoorsD.andinterference(/),theparentalscoresaresimilarandthehybridsvan*non-systematicallwOnthesixthmeas-

Lire,vocalization(V),allhybridgroupsscorewellaboveeitherparentalstock.Wegetamuchclearerpictureofthephenotypicdifferencesandpossiblegeneticmechanismsfromthisdetailedanalysisthanfromtheoverallperformancescore.

mechanismsfromthisdetailedanalysisthanfromtheoverallperformancescore.

Theleash-fightingscoreswerediscussedinchapter11whereastrongmaternaleffectwaspointedout.Thewithin-littervariancesoftheparentalandhybridgroupsaresetforthinTable12.2.UsingthevariancesoftheFiandF2,onecanestimateheritabilityas0.52.Thisisasomewhatlowerestimatethanthatbasedonthetwopurebreedsalone,0.77(seechap.14)butisofthesameorderofmagnitude.Itishigherthanthatobtainedforthetotaldemeritscore,reinforcingtheconclusionthatspecificscoresaremoremeaningfulthancomplexcombinedscores.

TABLE12.2

wlthin-llttervarianceofthefightingscoreofLeashTraining

Unfortunatelythebackcrossvariancesgiveamuchworsefittoasimplemodelthandothetotalvariancesanalyzedinthepreviouschapter;theBCS-CSvalueisunexplainablyhighandtheCSB-Bvalueistoolow.Dominanceofthebasenjigenescouldaccountforthisfindinginpart,butsuchaninterpretationisnotsupportedbythemeans,whichsupportthehypothesisofpartialdominanceofcockerspanielgenes.Similarinconsistenciesinthevariancesofthehybridsrepeatedlyturnedupinouranalysis,possiblydependentuponthescalesusedforphenotypicmeasurement,andpossiblyreflectingaccidentsofrandomsampling.Theorderingofmeansforthefightingandpositionscoresisconsistentwithgeneticdeterminationofthescores,butthewithin-groupphenotypicvariancesdonotincreaseproportionatelywithgeneticheterogeneity.Wecanseekthecluestothesourcesofwithin-groupvariationinacomparisonofrepeatedmatings.

Variationbetweenlittersofthesamemating.—Ifenvironmentalfactors(suchasthoseassociatedwithspecifictestersandmonth


oftesting)wereimportant,wewouldexpectrepeatedlittersfromasinglematingtovarywidelyfromeachother,sinceeachlitterwouldhavehadadifferenthistorv.Ontheotherhand,ifheredityhadplavedanimportantrole,successivelittersofamatingshouldberelativelysimilar.Maternaleffectscouldalsobeconsistentfromlittertolittersothatthiskindofenvironmentaleffectcannotbeexcludedbvthefindingofconsistencyofperformancebetweenrepeatedlittersfromthesameparentage.

fromthesameparentage.

Onlyapartofoursample(F2'sandbackcrosses)wassuitableforthelitters-within-matinganalyses,sinceeachofthesegroupscontainedseveralduplicatedmatings.TheresultsobtainedwiththefightingscoresarepresentedinTable12.3.Differentlittersofapar-

TABLE12.3

AnalysisofVariance—FightingScoresofHybridsbyMatings.andLitters

ticularmatingdifferinsignificantlyamongthemselves,althoughdifferencesbetweenmatingsarehighlysignificant.Theevidenceforcontroloffightingbygeneticsorbvmaternalinfluenceisthereforestrong.

Effectofsireanddam.—Inordertodistinguishbetweengeneticinfluencestransmittedequallybvbothparentsandassociativeinfluencesderivedsolelyfromthemother,amoredetailedanalysiswascarriedoutondatafrommatingsinwhichasinglesirewasbredtotwodifferentfemalesorasingledamtotwosires.Thegroupsavailableandtheirmeansonthefightingscoreoftheleash-controltestsaresetforthinTables12.4and12.5.Wehaveheretheequiva-

TABLE12.4Leash-ControlFightingScore—OffspringofFiSiresbyDifferentDams

COMPLEXBEHAVIOR

3C3

lentoffourexperimentswithsomesubjects,thebackcrosses,appearinginboththecommon-sireandthecommon-damexperiments.LookingatTable12.4,weseethattheoffspringofFisireshavefightingscoreswhichareontheaverageintermediatetotheparents.

TABLE12.5Leash-ControlFightingScore—OffspringofPurebredDamsbyDifferentSires

Allthevariationintheoffspringcanbeattributedtothedifferencebetweendams,becausethemalesusedhadalmostidenticalfightingscores.

InTable12.5wehaveanopportunitvtoseewhetherthemaleparentsinfluencedtheamoutoffighting.Itappearstomakenodifferenceastowhetherbasenji

theamoutoffighting.ItappearstomakenodifferenceastowhetherbasenjifemalesarebredtoCSorCSBmales,butinspectionofthescoresshowthatthetwogroupsofmaleshaveextremelysimilarfightingscores.CockerspanielfemalesproduceverydifferentoffspringwhenbredtoBandBCSmales;herethemeansofthesiresdifferby2.7.Weconcludethatthetransmissionoffightingbehaviorfrommalesisdemonstratedandthattheeffectmustbegenetic.

AmoreelaborateanalysisofvarianceofthedatasummarizedinTables12.4and12.5appearsinTable12.6.Ineachofthefouranalyses,thebetween-matingsumofsquareswaspartitionedintwoways:first,accordingtoindividualsiresordams,forexample,theoffspringoftheCSBmalesinPartA;second,comparingthesignificanceofthedifferencebetweenthemeansofthetwoclassesofoffspringproduced,forexample,inPartAthedifferencebetweenCSBXBandCSBXCSB.Inallfouranalysesthelitters-within-matingcontributiontovariancewasnon-significant,whichisgoodevidencethatchangesintesters,weather,andthelikehadlittleeffectuponthescores.Thewithin-matingmeansquarewasthususedasthedenominatorinthecomputationofFratios.

WeshallnowconsiderthetwosetsofmatingsofFisirestoparentalandFidams.NoneofthecomponentsintheBCSXBCSandBCSXCSexperimentwassignificant,thoughthedifferencebetweentheoffspringofthetwotypesofdamscameclose.Atfirst

TABLE12.6AnalysisofVariance—FightingScoreinLeashTraining

Degez•teofYak:Fee:SqdakbF

CSBgrudnringCSBXBAandCSBXC5B

Sires35.824.92**

Damsinsires45.514.6;"

Typeofdam19.177.74**

Betweenlikematings...65.064.27'"

Withinmatings711.18

BCSsireswithCSandBCSdamsproducingBCSXCSandBCSXBCS

Sires2

Sires2

Damsinsires3

Typeofdam1

Betweenlikematings4

Withinmatings56

resproducingCSBandCSBXBA

Dams3

Siresindams4

Typeofsire1

Betweenlikematings6

Withinmatings59

CSdamswithBAandBCSsiresproducingBCSandBCSXCS

Dams2

Siresindams3

Typeofsire1

Betweenlikematings.4

Withinmatings44

•P<.05"P<.01

glancetheCSBXBAandCSBXCSBexperimentslookquitedifferent.Thehighlysignificantmeansquarefordifferencesbetweensirescouldindicategreatheteropreneitvinthegeneticcharacteristicsofthemalesselectedfortheexperiment.However,intheanalysisofthedamscontributions,wefindahighlvsignificanteffectduetobreedofdam(basenjivs.CSB)andheterogeneitvbetweenmatingsofthesameclass.Inspectionofthephenotvpicscoresoftheparents(Table12.4)supportstheviewthatthevariationbetweensiresisaccountedforbythedamstowhichtheyweremated.AllfourCSBhadidenticalscoresof5.0,andtheirmatingswerenon-informa-^pecttotheinheritanceoffightingthroughthemaleparent.Fortunately,intheCSdamcrosses,typeofsirewasthemajorgeneticfactorinfluencingthefightingscores.Theformal

COMPLEXBEHAVIOR

analysisconfirmsthesignificanceofthedeductionsbasedoninspectionofgroupmeans.

Thusitisdemonstratedthatleashfightingcanbeinheritedfromeitherparent,andthefailurestodemonstratedifferencesamonglittersoftheFimaleswereapparentlytheresultofacurtailedrangeofphenotvpicdifferentiation.Thematingswhichcomparedunlikeparentsmatedtocommonparents,eithersiresordams,yieldedcleare\idenceofheritabilitv.

Wearehesitanttoestimateheritabilitvofthefightingscorefromthedataavailablesincenotallconditionsrequiredbythevariousmethodshavebeenmet.Itisinteresting,however,tonotetheregressionofoffspringmeansonmidparentvalues,b'},—0.4.54=0.135.Thisvaluewascalculatedfromallthehvbridandpurebredlittersforwhichdataonbothparentswasavailable.Theregressionofoffspringmeansondamswas0.233=0.0S0,ingoodagreementwithaheritabilitvestimateofabout0.45.Theregressionofoffspringonsireswasonly0.110,buttheestimateislessaccuratebecausetheaccidentsofsamplingproducedagroupofsireswithonlvhalfthevarianceofthedams.Thevaluesarelowerthanthoseestimatedfromthegroupdifferences.

Thefightingscoreshavebeendiscussedinsomedetailbecausetheyillustrate

Thefightingscoreshavebeendiscussedinsomedetailbecausetheyillustratetheproblemsofanalyzingtheinheritanceofarela-tivelvsimplequantitativecharacterofmoderatelvhighheritabilitv.

Comparisonofvocalizationwithleashfighting.—Vocalizingduringleashtrainingisofsomegeneralinterest,sinceyelpingisaconspicuousresponseandhasbeenusedasanindexofdistressinpuppiesFredericson.1952.Itisalsoofinteresttocomparevocalizationscores,whichshowedsuchadifferentpatternofmeans,withleashfighting.Allofthehybridgroupsscoredwellabovethemeansofbothparentalstocks,whichwerequitesimilartoeachother.Thecombinationofgenesfromthebasenjiandcockerspaniellinesthusfavorstheelicitationofvocalresponsesbythemildlystressfulprocessofleashtraining.Itshouldbenotedthatvocalizationontheleashisofadifferentsortfromthebarkinganalyzedinthelastchapter.

Adetailedanalysisofthevocalizationscoreswasmadeinthesamemannerasthatusedforthefightingscores.Withvocalization,however,theoffspring-midparentcorrelationwaszero.Thedatawerethenarrangedbymatingswhichinvolvedcommonsiresordams.ItisclearfromTables12.7and12.Sthatthescoresoftheoffspringhavenosystematicrelationshipstothemeanscoresoftheparental


TABLE12.7Leash-ControlVocalizationScore—OffspringofSiresbyDifferentDams

TABLE12.8Leash-ControlVocalizationScore—OffspringofDamsbyDifferentSires

groups.Ananalysisofvarianceuncoverednosignificantdifferencesbetweentheseparatematings.

Wehavehereaperplexingdifferencebetweenthehybridsandthepurebreeds.Differencesinvocalizationbetweenthefivebreedswerehighlysignificant(F<.01)andwereoneofthemostusefulscoresfordiscriminatingbreedbehaviorpatterns.Furthermore,itiswellknownthatvocalizationrespondstogeneticselection.Evidenceisprovidedeachtimeahoundbaysonthetrailoratoybreedbarksshrillyatastranger.Vocalizationintheleash-trainingtest,however,occurswhentwoconditionsaremetinthesamesubject—itmustbeemotionallvarousedandvocalizationmustbereadilyemitted.Byandlarge,ourcocker

arousedandvocalizationmustbereadilyemitted.Byandlarge,ourcockerspanielswerenoisyanimals,butthevwererelativelydocileontheleashandearnedaveragevocaliza-tionscores.Thebasenjiswerehighlyexcitedbytheleashbutdirectedtheirenergiesintochannelsotherthanvocalization.Thehybridswerearousedlikethebasenjis,andvocalizationwasafavoredresponse,possiblybecauseoftheirspanielgenes.However,thequantityolvocalization,oncethenecessaryconditionsweremet,wasindependentofheredity,asdemonstratedbythelackofaparent-offspringcorrelation.

MOTIVATIONTEST

Themotivationtest,describedinchapter10,wassimplyameasureofrunningspeedinaT-inaze.Onanyonetrialabarrierforcedthe

COMPLEXBEHAVIOR

307

dogtooneortheotherarmoftheT.Fivetrialsontherightandfiveontheleftweregivenoneachofthreeconsecutivedays.Thetotalrunningtimeonthethirddavwasourmeasureofmotivation.ThemeanscoresofthehybridgroupsandtheparentalstocksaregiveninFigure12.2.Theparentalstrainsweresignificantlydifferent,andbasenjisselectedasparentsforthehybridshadmuchlowerscoresthanthebreedasawhole.Themostinterestingfeatureofthedataistheelevationofthehybridscoresascomparedwiththeparents,asituationsimilartothatofvocalizationduringleashtraining.Ifwecanexcludeanvenvironmentaleffectwhichfavoredthehybrids(whichobviouslyweretestedatadifferenttimethantheirparents),itappearsthathybridsranfaster,perhapsduetophysicalsuperioritybasedupongeneticheterosis.Wepostulateadualmechanism—first,cockerspanielgenesascomparedwithbasenjigenesincreaseattractiontofoodandtohumanbeings.(Alternativelyonecouldinterpretthedataintermsofincreasedtimidityproducedbybasenjigenes,whichisperhapssayingthesamething.)Secondly,runningspeeddependsnotonlyuponthedegreeofattractionforthereinforcementprovidedattheendoftherunway,

6.0

5.0Ll)

<S4.0

3.0

B-B(34)

CSB.B(43)

P.F2

(52)(73)

BCS-CS(30)

CS-CS(40)

Fig.12.2.—Meanmotivationspeedscoresofhybrids.PointsidentifiedasinFig.12.1.ThemeansoftheactualparentsoftheF1hybridsareconnectedbyasolidline;themeansofthetotalbreedsamplebyadashedline.

butuponphysicalvigoraswell.Figure12.2canbeinterpretedasillustratinganeffectofphysicalvigorsuperimposeduponageneticsystemcontrollingtherelativestrengthofpositiveandnegativereinforcementinthetestsituation.


Wemadeadditionalanalysesoftheseparatehybridmatingsinanefforttoestimatethequantitativecontributionofhereditytotherunning-speedmeasure.Themidparent-offspringcorrelationwas.34±.20.Wemighttakethisasanestimateofheritability,buttheerrorofestimateisveryhigh.Analysisofvarianceofthegroupsinwhichonesirewasmatedtotwodams,oronedamtotwosires,showedconsiderableconsistency.Innoinstanceweretheresignificantdifferencesbetweenlittersofthesamemating,indicatingthatrearingandtestingconditionswerewellcontrolledoverthecourseoftheobservations.Ontheotherhand,individualmatingsdifferedsignificantlyatthe.01levelineachofthefoursetsofdataandintraclasscorrelationsof.15,.41,.24,and.24werecomputed.Allthesecomputationsagreeinsuggestingthatsomethingbetween20and30percentofthevariationinrunningspeedisheritable.Thiscompareswithanestimateof16percentbasedontheparentbreedsalone(seeTable14.3).

DISCRIMINATIONORCUERESPONSE

ThemotivationtestontheT-mazewasusedaspre-trainingfordiscriminationin

ThemotivationtestontheT-mazewasusedaspre-trainingfordiscriminationinadditiontobeingameasureinitsownright.Subjectswhichdidnotreachthecriterionwithin128trials(8dayswith16trials)wereclassifiedasfailures.InFigure12.3wepresenttheperformanceofthebasenji-cockerspanielhybridswithrespectto

DISCRIMINATIONCRITERIONATTAINMENT

FAILED

B.BCSB.B(23)(44

Fig.12.3.—Attainmentbyhybridsofcriterioninthecue-response(discrimination)test.Failureisdefinedasnotmeetingcriterionwithin128trials.

COMPLEXBEHAVIOR

309

attainmentofcriterionwithin128trials.Byusingasimplepass-faildichotomy,wefoundthedatayieldax2of25.532(F<.001).Therankingofthesixgroupsisorderlyexceptforthepurebredbasenjiswhichseemtobebetterthantheyshouldbeconsideringthatthebasenjibackcrossesweresoslowinlearning.Whenweconsiderthescoresofthespecificparents,wefindapossibleexplanation.Unfortunately,onlyfourofthesevenbasenjiparentspassedthroughthetestingprogramafterthediscriminationprocedurewasstandardized,andonlythreeofthefourmetthecriterion.Itisalmostcertainthatthebasenjisselectedasbreederswereaninferiorsampleofthebreed(forthistest).Thuswefeelsafeinconcludingfromtheorderingofgroupmeansthathereditymakesasubstantialcontributiontosuccessfuldiscriminationlearning.Theconclusionissubstantiatedbyananalysisofvarianceinthosehybridmatingswhichproduced

substantiatedbyananalysisofvarianceinthosehybridmatingswhichproducedtwoormorelitters.Ratherthanusetheattainmentofacriterionasameasureofsuccess,whichwouldhaveforcedtheexclusionoffailures,weusedthenumberofcorrectresponsesinthefirst64trials.Table12.9demonstratesthatthevariationsbetweenmatingsweresignificant(P<.05),andthatlittersofthe

TABLE12.9

DiscriminationorCueResponse—AnalysisofVarianceofHybridPerformance

P<.05P<.01

sameparentagecouldalsodiffertoaconsiderabledegree(P<.01).Eventhoughconditionsspecifictolittersareimportant,theeffectsofhereditaryfactorsshowthrough.Wehavenot,however,attemptedtoestimateheritabilityofthismeasurebecauseofourreservationsconcerningitsprecision.

DELAYEDRESPONSE

Subjectsmeetingthediscriminationcriterionweretestedondelayedresponsefollowingaseriesof50post-criteriondiscriminationtrials.Thesampleisobviouslynotrepresentativesinceinsome


groupsupto50percentoftheindividualsneverqualifiedforde-layed-responsetesting.Nevertheless,thefindingsareofsomeinterestandhavebeenillustratedinFigure12.4.Theproportionofindividualsmeetingthecriterionatdelaysof5secondsormorefluctuatesunsystematically,buttheproportionsmeetingthecriterionataminimumdelay(1second)appearfairlysimilar,animpressionwhichisconfirmedbyanon-significantvalue(x2of8.263,5degreesoffreedom,P<.10).

DELAYEDRESPONSEPERFORMANCEOFHYBRIDS100

Fig.12.4.—Attainmentbyhybridsofcriterionindelayedresponse.Failureisdefinedasnotmeetingcriterionat1-seconddelaywithin40trials.Blackportionofcolumnsindicatespercentageoffailures(definedasnotmeetingcriterionat1-seconddelaywithin40trials;barredareadenotespercentagepassingat1-seconddelay;whiteportionshowsthepercentageattainingcriterionat5-secondsorlongerdelay.

Thesedataprovidenoevidenceforgeneticdeterminantsofshort-termmemory,butthevariationsbetweenindividualswerestriking.Themaximumdelaysatwhichcriterionwasmetbyanyonesubjectwere:basenji,15seconds;CSBXB,5seconds;Fi,30seconds;F2,30seconds;BCSXCS,15seconds;andcocker,240seconds.Individualvariationmayhaveahereditarybasiswhichcouldbeinvestigatedbyselectingbothforgoodandpoordelaved-responseper-Formance.Onecouldretainforthelow-linethoseindividualswhichlearnedthecuediscriminationadequately,butfailedwhendelaywasintroduced.Onlybysuchaprocedurecanthehigherorderabilitybedisentangledfromsimplediscriminationlearning.

COMPLEXBEHAVIOR

311

OBEDIENCETEST

Theobediencetestwasinterpretedasameasureofeaseofinhibitorytrainingonthebasisofthecomparisonbetweenthefivepurebreeds.Sincethecockerspanielsandbasenjisdifferedsharplyonthetest,onemightanticipatethatthehybridswouldbeintermediate.TheexpectationisverifiedinFigure12.5,whichshowsthe

Fig.12.5.—Meanscoresofhybridsonobedience.Highscoresindicategreaterinhibitionofmovement.PointsidentifiedasinFigure12.1.

meanscoresofparentalandhybridgroupsincludingthevaluesforthebasenjisandspanielsselectedasparentsofthehybrids.Thedataarenotperfectlyorderly,butthetrendisclear.Themoredetailedanalyses,unfortunately,arelessinformativethantheywerefortheleash-trainingtest.Theoffspringonmidparentregressionisonly.16,notreliablygreaterthanzero.Analysisofvariancefailedtouncoveraconsistentdifferencebetweenmatings,andsuccessivelittersofthesameparentagewereoftenasdifferentastwomatings.Despitethefavorablemeandifferencebetweenthebreedsandtheapparentorderlinessofthegroupmeans,weendedwitharatherunsatisfactoryoutcomeofthegeneticanalysis.Intuitivelythetestseemedtobeasgoodacandidateforhighheritabilityastheleash-fightingscore,butintuitionprovedapoorguide.


REACTIVITYTEST

Asdescribedinchapter8,subjectsinthereactivitytestwererestrainedbylooselyfittingloopswhiletheywerestimulatedinsequencebytheentranceofanexperimenter,bythesoundofabell,andbyfourmildshocksappliedtothehindleg.Measuresincludedratingsofpostureandvariouscategoriesofbehavior,andcontinuouslyrecordedrespiration,electrocardiograms,andelectromyo-grams.Twenty-threemeasureswereselectedfordetailedanalyses,andtheresultsonthefivepurebreedshavealreadybeenpresented.

Inadditiontothesepartscores,thetotalreactivityscoreobtainedbysumming

Inadditiontothesepartscores,thetotalreactivityscoreobtainedbysummingalloftheovert-behaviorratingsisusefulasageneralbasisofcomparison.Ahightotalreactivityscoreindicatesagen-

U6

z

<

»-4I/)

TOTALREACTIVITYSCORE17Weeks

Fig.126.—Moantotalreactivityscoresofhybridsat17weeks(upper)34weeks*middle),and51weeks(lower).

COMPLEXBEHAVIOR313

erallvactiveanimal.Basenjisweresignificantlyhigheronthismeasure(meanstaninesbetween5.5and6.0)thancockerspaniels(meanstaninesbetween3.5and4.0).ThemeantotalscoresofthehybridgroupsareshowninFigure12.6.Oneinterestingfeatureofthisfigureisthechangeassociatedwithmaturity.At17weeksofage,allthehybridsareasreactiveasthebasenji;by51weeksthemeansapproachtheexpectationbasedonadditiveinheritance.TheCSBFi'sappeartobetoohigh,butthismaywellbeasamplingphenomenon.Unfortunately,thereactivityscoringsystemhadnotbeenstandardizedwhensomeoftheparentsweresubjectsintheprogram,sothatitisimpossibletoknowwhethertheparentsofthetwoFi'swereequalinreactivityscores.

Thedetailedanalysisofgroupmeansontheseparatemeasuresatthreeagesdid

Thedetailedanalysisofgroupmeansontheseparatemeasuresatthreeagesdidnotaddgreatlytotheinformationobtainedfromthetotalscorecomparison.Onthosesubscoresinwhichbasenjisandspanielsweredefinitelyunlike,thehybridstendedtobeintermediate.Inparticular,themeansofthebackcrossesandFi>'susuallyfellclosetoalinedrawnbetweentheparentmeansasinFigure12.6;theFimeansvariedmorewidelyfromtheexpectationbasedonadditiveinheritanceanduniformenvironment.Onsomescorestheparentstocksdifferedinsignificantlyandthepatternsofthehybridmeanswereirregular.AsillustrationsweshowinFigure12.7themeansforfourofthesubscoresfromthe34-weektest.Thegroupmeansforthephysiologicalmeasure(basalheartrate)fallclosetotheexpectationbasedonadditiveeffectsofgenes.Theactualmeansinbeatsperminutewere:basenji,138;basenjiback-cross,134;Fi,117;F2,114;spanielbackcross,109;andcockerspaniel,102.Similarresultsfortheheartrateofyoungpuppieswerereportedinthepreviouschapter.

Thedataforbodypositiondidnotfallasneatlyinlinewithexpectations,butallhybridmeanswereintermediatebetweenthespaniels,whoselowscoreindicatestheprevalenceofcrouching,andthebasenjiswhichalmostalwaysstooderect.

Thedistributionofbitingandtail-waggingscoreswerediscontinuoussothatstaninetransformationswerenotfeasible.Seventy-eightpercentofthebasenjisbitattheirrestrainingloops,butonly10percentofthecockersdid.Thepercentagesofbitersinthehybridgroupsformanorderlyarray,althoughthespanielback-crossesareasnon-aggressiveasthepurebredspaniels.Thedichoto-mousclassificationforgraphicpurposesintobitersandnon-bitersobscuresthefactthatthe7to10percentofcockersandcockerbackcrossesthatwereratedasbiterswereonlymarginallyso.


Bitingisanillustrationofbehaviorwhichdoesnotappearuntilathresholdofstimulationisreached.Givenastandardstimulus,populationsdifferintheproportionwhichshowanyresponse.Oncearesponseiselicited,itcanbeexpressedinquantitativeterms.Suchcombinationsofcontinuousanddiscontinuousvariationarenotconvenientforgeneticanalysis.FormalanalysiscanbedonewithWright's(1934)thresholdmodel(seeFuller,Easier,andSmith,1950,foranapplicationofthismodeltoseizuresusceptibilityinthe

BACSB.BFt)FzBCS.CSCS

BACSB.BF,,F2BCS.CSCS

Fig.12.7.—Ontheleft:meanscoresofhybridsontworeactivity-testmeasures.ThetwoFjandF2populationswerepooled.Ontheright:theproportionofeachhybridgroupscoresas"high"ontworeactivitytestmeasures.Straightlinesbetweenparentalmeansindicatelocationofhybridmeansifinheritancewereadditive.AdditionallinesconnectparentalmeanswiththeF1tovisualize"dominancedeviation."

mouse),butitisnotusefultocarryoutsuchproceduresonsmallsamplesfromnon-inbredparentstocks.Wecansafelyconcludethatgenotypeaffectstheprobabilityofelicitingbitingundermildrestraint;but,beyondassertingtheprobableapplicabilityofathresholdmodel,wesuggestnospecificmodeofinheritance.

ThefinalpartscoreillustratedinFigure12.7isfortailwaggingandisdistributeddiscontinuouslylikebiting.Theproportionsofthetwoparentstockssurpassingthethresholdofstimulationarenotgreatlydifferent,andthehybridgroupscoresarelikewisesimilar

COMPLEXBEHAVIOR

315

toeachother,withmeansdifferinginsignificantlyfromthatofthecockerspaniels.Theincidenceoftailwaggingchangedmarkedlyoverthethreetests.Figure12.8demonstratesthatthegeneralrelationshipbetweenthegenetic

Figure12.8demonstratesthatthegeneralrelationshipbetweenthegeneticgroupsremainsroughlythesame,althoughtheproportionsshowingthebehavioraredecreasing.

100

CSB-B

F,,F2BCSCS

Fig.12.8.—Proportionofeachhybridgroupratedas"high"intailwaggingat17weeks(opencircles),34weeks(half-filledcircles),and51weeks(solidcircles).

Changesassociatedwithagingappeartoactuniformlyoverthevarietyofthegenotypestested.Ingeneral,thedifferencesbetweentheparentbreedsarenotaspronouncedasearlierindevelopment(seechap.4).

Itisnotcoincidencethatmostofthepartscoresinthehybridsfollowthegeneraltrendofthetotalscores.Theratingsystemwasdevisedtoyieldhighnumericalscoresforthedogwhichfoughtagainstrestraintandwhichrespondedactivelytoeachnewsetofstimuli.Lowscoreswereassignedforinactivityandabsenceofphysicalevidenceofarousal.Thefactthatthemeansforthetotalscoresfallinanorderlysequenceinthehybridsmaysignifythatsomecommondimensionofarousalvs.inhibitionismanifestedin


avarietyofways.Theprecisemannerinwhicharousalisexpressedinthereactivitysettingmaynotbeasimportantasthelevelofactivationattained.

TABLE12.10Variance—TotalReactivityScoresofHybrids

Furtherinformationonthecontributionofhereditytothereactivityscorewasobtainedbvananalysisofthehybriddatabymatings.Thegeneralformofthisprocedurehasbeendescribedabove.ReactivityscoresforthethreetestsweresummedforthisanalyLittersofamatingdifferedinsignificantlyfromoneanother—evidencethattheeffortstomaintainconstantrearincrandtesting;con-ditionsoverthecourseoftheexperimentweresuccessful.Variationattributabletomatingswashighlysignificantineachofthefoursub-experimentsintowhichwehavegroupedthedata.ThesummaryanalysisofTable12.10wasmadewithoutrespecttogeneticclassificationandincludesdatafrom21hvbridmatingswhichproduced37litters.Theintraclasscorrelationof.736isoneofthehighestfoundonanyofthetests,muchhigherinfactthanwasfoundinthepure-breedcomparisons.Itshouldbeemphasizedthatthishighvaluecomesfromtheclassificationofoffspringbyindividualparentageandnotbvthebreedclassificationoftheparents.Althoughreactivityisheritable,differentindividualsfromtheparentstrainspassonquitedifferentgeneticdeterminantstotheiroffspring.

Hadthisbeenforeseen,wemighthaveelectedtodisregardbreedboundariesinplanningmatingsandworkedentirelywithparent-offspring,sibling,andhalf-siblingcorrelations.TheheterogeneityinphenotypeofmatingsofthesametypeisillustratedforthereactivityscoreinTables12.11and12.12.Differencesbetweenmatingsofthesametvpeweresignificantintheseexperiments:CSBfXB9orCSBi(P<.01;HA2XCS6orCSBJ(F<.01;andCSe•HA!orBCSP<.05).Thenumberofdifferentmatingsistoosmalltopermitanyconclusionsontherelativecon-

COMPLEXBEHAVIOR

317

TABLE12.11

TotalReactivityRatings(Sumof3Tests):MeansofMatingsofPurebredDamsbyPurebredandFiSires

tributionsofdamandsire,butthedataareconsistentwithequalcontributions

tributionsofdamandsire,butthedataareconsistentwithequalcontributionsfrombothparents.ThedifferencebetweenreciprocalFi'scouldbeinterpretedasanexampleofmaternalinfluence,butitisequallylikelytobeanexampleofsamplingvariation.

Thesedataagainconfirmtheconclusionthatthebreedsstudied,thoughselectedinpartforbehavioralcharacteristics,arestillheterogeneous.Selection,ofcourse,hassucceededinmakingbreedssignificantlydifferentontheaverage,aswefoundinourbreedcomparisons.

TABLE12.12MatingsofFiSiresbyPurebredandFxDams


LJ

<X00

BACSB-B

FiF2

BCS-CSCS

Fig.12.9.—Meancorrectchoicesscoresofhybridsonthespatial-orientationtest.LinesdrawnasinFigure12.7.

SPATIAL.ORIENTATIONTEST

Aswithdiscriminationanddelayedresponseitwasnecessaryinthespatial-orientationtestforsubjectstomeetaspecifiedcriterionduringpre-traininginordertoobtainmeaningfulmeasuresonthestandardprocedure.Sincesomedogsfailedtomeetthecriterion,thecomparisonsbetweengeneticgroupswerebaseduponselectivesampling.Thetotalnumberofsubjectsenteringtrainingforeachgroupfollows,withthenumberfailingtomeetthecriterionforthetestgiveninparentheses:basenji,28(4);CSBXBA,43(4);BAXCS,24(0);CSB,28(1);BCSXBCS,32(1);CSBXCSB,41(4);BCSXCS,27(1);andcockerspaniel,28(2).

ThemeansinstaninesofthegroupsforthethreemeasuresareshowninFigures12.9to12.11.Thecockerspanielsweredefinitelysuperiortobasenjisin

12.9to12.11.Thecockerspanielsweredefinitelysuperiortobasenjisineliminatingerrors.Allofthehybridgroupsweresuperiorontheaveragetothebetterparent.ThepersistencescoresfellintoasimilarpatternexceptfortheFi'swhichwereintermediatetotheparents.Allhybridgroupsweresimilartothecockerspanielsontheadjustedspeedmeasure.Althoughthispatternofdistributionofthemeansdoesnotappearfavorableforaquantitativeanalysis,wesubjectedthecorrect-choicescorestoan

COMPLEXBEHAVIOR

319

7.0

6.0-

QJ

2

5.0-

4.0-

3.0

BACSB.BF,,F2BCS-CSCS

Fig.12.10.—Meanpersistencescoresofhybridsonthespatial-orientationtest.LinesdrawnasinFigure12.7.

analysisofvariancetodeterminedifferencesbetweenmatingsandbetweenrepeatedlittersfromthesamemating.Itwasnotsurprisingtofindnosignificanteffectofmatingssincethegroupmeansweresomuchalike.However,thedifferencesbetweenlittersofthesamematingweresignificantinthreeofthefourseparateanalyses.

Weconcludethatsomethinginthetestsituationorinthegrouplifehistoryexertedapowerfuleffectuponperformanceinthespatial-orientationtestwhichoverrodeanyinheritedvariationsinlearningability.Sincelittereffectswerenotdetectedinothermeasuresinwhichtheyweresought,itisprobablethattheeffectinthespatial-orientationtestarosefromsomefactorpeculiartothattest.

effectinthespatial-orientationtestarosefromsomefactorpeculiartothattest.Theapparatus,becauseofitslargesize,wassetupintheanimals'homepenssothatconditionsoftestingvariedfromlittertolitter.Theconsequencesofbadweather,disturbancesfromadjacentpens,etc.maybemanifestedintheanalysis.

Despitetheinappropriatenessofthedataforquantitativegeneticanalysis,webelievethatthesuperiorityofthehybridsoverthebasenjiparentsisarealgeneticeffect.Thebasenjisasagroupwerestereotypedintheirresponses,tendingtorepeaterrors.Theyalsowereeasilydistractedbyextraneousstimuliwhichincreasedtheirerrors.When25,50,or75percentofthegenotypewasofcocker


7.0

CSB-BFt1f2BCSCS

Fig.12.11.—Meanadjustedspeedscoresofhybridsonthespatial-orientationtest.LinesdrawnasinFigure12.7.

spanielorigin,theimprovementwasnotable,althoughnotcorrelatedquantitativelywiththeproportionofspanielgenes.Againitseemedthatwhenathresholdoftimiditywassurpassed,learningwasreasonablyadequateinallsubjects.Tobesure,individualdifferenceswereconspicuousandthesemaydependuponsomeheritablecognitiveability.Themajorgroupdifferencesinsolvingthespatial-orientationproblem,however,seemtoberootedinemotionalreactivitytothetestprocedure(seediscussionof"fearofapparatusfactor,"

reactivitytothetestprocedure(seediscussionof"fearofapparatusfactor,"chapter14).

Insummary,methodsofanalysiswhichdonotdependupontheassumptionofgenetichomozygosity,confirmtheimportanceofhereditaryeffectsupontheoccurrenceofsimplepatternsofbehaviorsuchasleashfightingandemotionalreactivity.Theydonot,however,assistgreatlyintheanalysisofgenetictransmissionofthecomplexadaptivebehaviorinvolvedinproblemsolving.Importantbreeddifferencesinproblemsolvingexist,butthecomplexityofinteractionbetweenthebasiccapacitiesinvolved,bothonthephysi-ologicalandbehaviorallevels,issogreatthatthesemethodscannotcopewithit.

Hereditaryeffectsuponbehaviorrelatedtoeaseofemotionalarousal,specificemotionalresponses,andlevelofmotivationwereclearlvdemonstratedbvthehybridizationexperiment.Ontheotherhand,thecapacitiesforvarioussortsofproblem-solvingbehaviorwerenottransmittedinasimplemanner,andevidenceforheritabilitywasoftenweakorentirelylacking.Itmaybethatlearningabilitvisnotheritable,andthatthestrikingindividualvariationsobservedwerereflectionsofdifferentialexperience.Thisseemsunlikely,however,inviewofthestrongevidenceofheritability,basedonbreeddifferences.Wearereservingfinaljudgmentonthismatteruntilselectionexperimentsareperformedusingproblemsolvingasthecriterion.Atpresent,wecandefinitelystatethatpuppiesresembletheirparentsmorein"personality"thaninintelligence,perhapsbecauseprimarygeneproductshavemoredirecteffectsuponpersonality.

AGENERALINTERPRETATION

Theresultsofthehybridizationexperimentareatthesametimeilluminatingandperplexing.ThetendencyoftheFiandF2hybridstoreceivescoresintermediatetotheparents,andforthebackcrossestobeintermediatebetweentheFiandtheotherparentwasverystrong.Incontrasttotestscitedinthelastchapter,noevidenceofsegregationintodistinctphenotypicclasseswasfoundineithertheF2'sorthebackcrosses,aresultconsistentwiththeinterpretationthatthespanielsandbasenjisdifferedatmultipleloci,eachofwhichaffectedthecharacterstudied.Furthermore,thewithin-littervariancesoftheF2andbackcrosseswerenotalwaysgreaterthanthoseoftheFiandparents.Suchafindingsometimeshascausedconsternation,butthereappeartobethreegoodexplanationsofwhyweshouldnotexpectthevariancesofthesegregatinggenerationstobelargerthanthatoftheparentsandFi.First,thereisampleevidencethatthebasenjisandcockerspanielswereheterozygousatmanyloci

evidencethatthebasenjisandcockerspanielswereheterozygousatmanylociwhichaffectbehaviorsothattheassumptionofnegligiblegeneticvariationinthesepopulationsisunwarranted.Second,ifmanylociareinvolved,theproportionofextremegenotypesproducedinthesegregatinggenerationswillbelowandtheresultingincreaseinvariancewillbeindistinguishablefromsamplingerrorinasmallpopulation.Third,theheritabilityofmanycharactersislowenoughsothatasmallincreaseingeneticvarianceisindistinguishablefromsamplingvarianceexceptinlargepopulationsinvolvingmanymatings.


Assuggestedabove,thefindingsindicatethatadifferentexperimentaldesigninvolvingalargernumberofmatingsfromawiderselectionofbreedswouldhaveprovidedmorepreciseknowledgeconcerningthegeneticstructureofdogpopulations.Butsuchaplanwouldnothavesuppliedasmuchinformationonthecrossingofphenotypicallydistinctbreedswhichhadbeengeneticallyseparatedformillenniums.Thespanielswere,ingeneral,superiorperformersonthosetasksinwhichtheterms"superior"and"inferior"areatallappropriate.Inthetrainingprocedures,spanielsweremorereadilyinhibited,whichmaybedesirableorundesirabledependinguponcircumstances.Onmanyperformancetests,thehybridswereequaltoorsuperiortotheparentthatwasthemoreactiveorthebetterlearner.Webelievethatadual-processhypothesiswillaccountforsuchfindings.Inthespatial-orientationtest,themorereactivebasenjisarestronglystimulatedbysmallvariationsintheenvironment,andthesevariationsinterferewithsuchtasksasdiscriminationandthelearningofacorrectpath.Inthesesametestssomecockerspanielsshowlittledistractionandalsolowspontaneousactivityresultinginrelativelypoorperformance.Thehybridsofalldegreesappeartobehighlyarousedlikethebasenji,andnon-distractablelikethecocker,sothatperformanceisfrequentlysuperiorontheaveragetoeitherparent.

Thecharacteristicsofthetwoparentalstocksarereasonablyaccountedforbypastselection.Basenjis,livinginvillagesintheAfricanjungles,aregivenrelativelylittleprotection.Suchcircumstancesplaceapremiumonawarenessofminorchangesintheenvironmentandexcessivecautiontowardastrangeobjectorindividual.Cockerspaniels,ontheotherhand,haveledahighlvprotectedexistenceasEnglishhuntingdogsandashousepets.Theywereselectedoriginallyonthebasisofgreatactivityinhuntingbuteaseofinhibitionofattackongame.Thoughsuchselectionhasbeenrelaxedinmanystrains,thepopularityofthespanielasahousepetisbasedinpartuponitsreputationfordocility.

Determinationofdominancerelationshipsbetweenthegeneticsystemsresponsibleforthesephenotvpes(shynessvs.inhibition)couldbemadeonlyifagreementcouldbereachedonthescaleforphenotypicmeasurement.Ourdataindicatethattheshynessofthebasenjimaybedependentuponarelativelysmallnumberofgeneswithgenerallyadditiveeffects,andthatasimilarsysteminvolvingdifferentgenesisassociatedwiththeinhibitabilityofthecockerspaniel.Suchdualsystemscouldexplainthefactthatonsomemeasuresthebackcrossesweremorebasenji-likeormorecocker-likethan

COMPLEXBEHAVIOR323

thepurebredstocks.Abasenjibackcrosshomozygousornearlysoforshynessandalsohomozygousornearlysoforinhibitionwouldperformlesswellperhapsthanapurebredbasenjiwhichwaslessinhabitable.

Weshouldstressthatthebasenji-cockerspanielhybridswerephysicallyandbehaviorallyexcellentanimals.ThepointisimportantbecauseStockard's(1941)statementsregardingdisharmoniesintheF2ofinterbreedcrosseshavebeencitedasevidencefordangersinherentinracialcrossesinman(George,1962).Stockard,ofcourse,startedwithbizarretypesofdogssuchassalukis,dachshunds,andbulldogs,whichhaveachievedaratherperilousgeneticadjustmentastheresultoflongperiodsofselection.Itisnotsurprisingthatjaws,limbs,andbodiesoftheF2'sdidnotfittogetherverywell,althoughtoanaiveMartianseeingdogsforthefirsttime,theFs'smightappearnomorestrangethanapurebredbulldogoradachshund.Asthephotographsshow,ourbackcrossandF2groupsincludedindividualswhichconformedtononeofthet\pesrecognizedaspurebreeds,butwhichwerenonethelesshealthy,vigorous,andwelladjusted.

GOALSFORBIOMETRICALGENETICSOFBEHAVIOR

Thisisperhapsasuitableplacetorecordourchangeofattitudetowardourexperimentsaswegathereddataandsubjectedthemtoquantitativeanalysis.Atthebeginningofthehybridizationexperimentwewerelookingforgeneticmechanismstocorrespondwithhypotheticaltraits.Asdataaccumulated,itbecameclearthatcorrelationsbetweendifferenttestsgivenatdifferenttimesandplaceswerelow—inotherwords,wefoundlittleevidenceforpervasivetraitsaffectingallaspectsofbehavior.Tobesure,thefactor-analysesofRoyce(1955)andBrace(1961)uncoveredmanysignificantcorrelations,butthesewerehighestbetweenmeasurescollectedinthesametestsituation.Overtheperiodof

highestbetweenmeasurescollectedinthesametestsituation.Overtheperiodoflifewithwhichwewereconcerned,traitstructurewassomewhatfluid,andgenetichypothesesregardingheritabilitywereconsequentlyspecifictoaparticularageandtypeofmeasurement.Attemptstosecuregreaterprecisionbysubstitutingfactorscoresbasedonacombinationoforiginalscoreswerenotsuccessful.Wesomewhatregretfullycametotheconclusionthatclassicalbiometricalmodelsarenothighlyapplicabletotheinheritanceofcomplexbehaviorinsemi-naturalpopulations(casuallyselectedforbehaviorandnotsystematicallyinbred).Ifwecantransfertothedogthefindinginmicethatmuch


ofthegeneticvariationamonghybridsisattributabletointerlocusinteractions(Fuller,1964),wewouldexpectrelativelylowparent-offspringcorrelations.Untilbettermethodsaredevised,formalbio-metricanalysiswillbemostfruitfulinspeciesinwhichnumerousinbredlinesexist,andinwhichlargenumberscanbebredatlowercost.Insuchsituationsthebehavioralphenotypecanberigorously(andnarrowly)specified,andthesuccessofthebiometricalapproachhasbeenamplydemonstrated(FullerandThompson,1960;Broadhurst,1960;Bruell,1962;HirschandErlenmeyer-Kimling,1962).

BroadhurstandJinks(1961)haveattemptedthebroaderapplicationofelaboratemethodsdevelopedfortheanalysisoftheeffectsofgeneticsoncontinuousquantitativevariationinbehavior,basedonthetechniquesofMather(1949).Withthesemethodsitispossibletoestimatetheamountofvariationduetodominance,additiveeffectsofgenes,andinteractionbetweenthem,aswellasthatduetoenvironmentalfactors.Usingasetofincompletedatafromoneofourproblem-solvingtests(Scott,1954),theyarrivedatanestimateofheritabilityapproximatelytwiceaslargeasthatobtainedbyusandbasedonbreeddifferencesalone.Suchmethodsgiveushopethatthequantitativeeffectsofheredityonbehaviorcanbeanalyzedmoreexactlyinthefuture.Becausethesemethodsdependuponempiricalscalingofeachindividualtestandhencebecomeextremelylaboriouswhenappliedtolargebodiesofdata,theyhavenotbeenappliedhere,althoughitwouldobviouslybefruitfultousethemoncertainsetsofthesedataandtocomparetheresultswiththoseobtainedbyothermethods.

Cantheresultsobtainedinspecializedlaboratorypopulationsbeappliedtolarger,moreheterogeneousgroupssuchasdogbreedsormankind?Inparticular,weaddressourselvestotheinterpretationofheritabilities.Heredity,inthebroad

weaddressourselvestotheinterpretationofheritabilities.Heredity,inthebroadsense,isusuallyassumedtoexplaindifferencesbetweenspecies.Occasionalinterspeciescrossesareavailablefortestinggenetichypotheses,butsuchresultscanhavelittleapplicationtonaturalspecieswhicharedefinedasindividualssharingacommongenepool.Thevariationsinbehaviorbetweenracesorbreedsofthesamespeciesare,parentalinfluencesaside,primarilygenetic,butthesearereflectionsofinterallelicinteractions(epistasis)aswellasofadditiveeffectsofgenes.

Oneshouldbecautiousinapplyingquantitativefiguresforheritabilityoutsideofthespecificcontextinwhichtheywereobtained.Wequestionwhether,oncesomegeneticcontrolofacharacterhasbeendemonstrated,preciseestimationsofheritabilityhaveany

COMPLEXBEHAVIOR325

greatvalueexceptforselectionprogramswithpracticalobjectives.Hereestimatesofheritabilitvforthecriterioncharacterobtainedunderconditionspeculiartotheselectionprojecthaveobvioussignificance.

Tous,itappearsthataspecieslikethedogismostusefulinbehaviorgeneticsforstudiesofgenotype-life-historyinteractions.Suchinteractionsneednotbestatisticalabstractionsfromanalysisofvariancetables,butcanbeexpressedinfunctionaltermsbaseduponobservationandmeasurementofbehavioratvariousstagesindevelopment.Forthispurpose,agroupofpurebredstrainsofdivergentphenotvpes(excludingmonstrosities)canbeextremelyuseful.

Resultsfromsuchstudiescanbeorganizedintheformofamatrixwithvaryingnumbersofrows(ofbreeds)andcolumns(ofenvironments).Suchamatrixisgeneratedbyanyexperimentcomparingtwoormorebreedsintwoormoreenvironments.

Ourbreedcomparisonstudyinoneuniformenvironmentformedamatrixwithonecolumnandelevenrows.Forcomparativepurposesinfutureinvestigations,werecommendtheadditionofanadditionalrowintheformofa4-waycross,FiXFi,witheachF,derivedfromadifferentpairofbreeds.Insuchapopulationoneobtainsvariablegenotypeswhichfacilitatecorrelationalanalysis.Furthermore,suchageneticallydiversepopulationcanbeusedasacontrolforthegeneralityoffindingswiththepurebreeds.

Forthefuturewealsorecommendadditionalcolumnsofenvironmental

Forthefuturewealsorecommendadditionalcolumnsofenvironmentaltreatmentswhichwillenabletestingofthevalidityofvarioustheoriesconcerningtheeffectofearlyexperienceandtrainingupondifferentgenotypes.Thestandardizedenvironmentgivenourpuppieswasrestrictedinmanyways,anddifferentkindsoftreatmentsmightwellresultinthedevelopmentofcapacitieshiddeninthisexperiment.

DEVELOPMENTOFPHYSICALDIFFERENCESANDTHEIRRELATIONTOBEHAVIOR

NTRODUCTION

Inpreviouschapterswehavebeenconcernedalmostentirelywiththedevelopmentofbehaviorandtheevidencethatgeneticsproducesbehavioraldifferentiationandvariation.Thischapterisconcernedwithoneaspectofthegeneralproblemofhowgeneticsaffectsbehavior:theeffectsofdifferencesinphysique.Thisisanimportantpracticalproblem,foriftherewereaperfectcorrelationbetweenphysiqueandbehavior,thetaskofthebehaviorgeneticistwouldbeenormouslysimplified.Itisalsoaninterestingtheoreticalissue,involvingboththeconceptofpleiotropy,ormanifoldeffectsofthegene,andtheapplicationofthecontrastingconceptsoftypeandpopulationtotheanalysisofvariation.

Physiqueistheresultofgrowth,aprocesswhichhasonlvanindirectrelationshiptobehavior.Somedifferencesinbehaviorcanbeseenonlywhenphysicalgrowthliasreadiedacertainpoint,anddifferencesinsizemayhaveimportanteffectsoncertainmotorcapacities.However,thedevelopmentofsizeandotherphysicalcharacteristicscanserveasamodelfortheactionofheredity,partlybecauseitismuchclosertothephysiologicaleffectsofgenes,andpartlybecauseweknowsomuchmoreabouttheinheritanceofsizedifferences.

PATTERNSOFGROWTHINTHEDOG

Growthinrelationtoperiodsofbehaviordevelopment.—Forthefirst3weeksofitslife,apuppynormallyreceivesallitsnourishment

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327

327

bynursingfromitsmother.Themilksupplydoesnotincreaseasthepuppvgrowsolder,butreachesthelimitofthemother'scapacityafewdavsafterbirth.Thegeneralgrowthpatternreflectsthislimitation,andtheneonatalpuppygainsthemaximumamountinthesecondweekandslightlylessinthethird(Fig.13.1).

_500

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Fig.13.1.—Absoluteweightgainperweekinmalepuppiesofthelargestand

Fig.13.1.—Absoluteweightgainperweekinmalepuppiesofthelargestandsmallestbreeds(beaglesandterriers).Notethatthismeasureismuchmoresensitiveandvariablethancumulativeweightcurves.

At3weeksofage,thepuppiesbegintotakesupplementalfood.Underourspecialconditionsofrearing,theynowhaveaccesstoanunlimitedfoodsupply,andthisisreflectedintheirgrowthrates.From3to7weeksofage,thereisanincreaseintheamountgainedperweek,thechangetakingplacegraduallyorsuddenlydependingonhowquicklytheindividualpuppyorbreedbecomesadjustedtosolidfood.Thereisatemporarysetbackatthetimeoffinalweaning,butforseveralweeksthereafterthepuppiesgainaconstantamounteachweek(abouthalfakilograminanaveragemalebeagle).Thedipat16weeksinFigure13.1isprobablycausedbyreactiontodistempershotsinsomeanimals,asCorbinetal.(1962),reportaconstantincrementupto18weeksofage.

Thesefactsarereflectedinconventionalgrowthcurves.There


appeartobeupperlimitsfortheamountsofeitherliquidorsolidfoodwhichapuppycanprocess,sothatweightgaincurvesareflatupto3weeksofageandagainfrom7weeksonward(Fig.13.1).Sinceweightgainisnotproportionaltosize,percentagecurvesdeclinethroughoutdevelopment.Thecumulativeweightcurveupto16weeks,thoughsuperficiallysimilartoatheoreticalexponentialgrowthcurve,isactuallycomposedoftwostraightlinesconnectedbyacurvedportionreflectingincreasingintakeofsolidfoodbetween3and7weeks(Fig.13.2).

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BASENJIMALES(N=23)

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Fig.13.2.—Combinedgrowthcurveforbasenjimales.Notehowvariationincreasesastheanimalsbecomelarger.

Forourpuppiestherewasasecondchangeindietat16weeks,whentheywereputoutdoorsandnolongergivensupplementsofmilkandfinch'powdereddryfoods.Mostofthebreedsshowedalessenedrateofgainduringthenexttwoweeks(Fig.13.4),butthismayhavereflectedthefactthattheywerenolongerdrinkingaquarterofakilogramofmilkbeforebeingweighed.

Alter16toISweeks,theincrementsofgrowthgraduallydecline.

PHYSICALDIFFERENCES

329

Bythistimethepuppiesaremorethanhalfgrownandbeginningtoapproach

Bythistimethepuppiesaremorethanhalfgrownandbeginningtoapproachadultcapabilities,althoughtheyarejustbeginningtogettheirpermanentteethandwouldnotundernaturalconditionsbecapableofeffectivehuntingforanothermonthortwo.

Thisgeneralpatternofgrowthisadaptedtothelifeofacarnivore.Apuppygrowsasrapidlyaspossibleuntilhereachesthesizewhichenableshimtobeaneffectivehuntinganimal.Thiscontrastswiththepatternofgrowthinhumanbeings,inwhomaperiodofrapidgrowthinearlyinfancvisfollowedbyaperiodofveryslowandgradualgrowthuptoshortlybeforepuberty,whenanadolescentspurtappears.Thereisnothinglikethehumanadolescentspurtinthedevelopmentofthedog,unlessweconsidertheearlyperiodofrapidgrowthassuch.Itshouldbecalleda"puppyhoodspurt,"ifanything.

Breedandsexdifferences.—Thereisalwayssomeoverlapbetweenindividuals,butineverybreedandatanyagethemalesareontheaveragelargerthanthefemales(Fig.13.3).Bythetimetheyreachoneyear,themalesinbeagles,cockers,andsheltiesarefrom24to28percentheavierthanthefemales.Thedifferencesinterriersandbasenjisismuchless,being12and14percent,respectively.

Thesedifferencesingrowthcurvessuggestthatthefemalesmaybematuringmorerapidlythanthemalesandhenceslowingdowningrowthatanearlierage.However,ifwecomparethepercentagesofadultweightat16weeks(Table13.1),itisobviousthatthefemalesareverylittleaheadoftheirbrothersexceptinthebeagles,wherethefiguresare61percentforfemalesand55percentformales.Inbasenjisthefemalesareslightlybehindthemales.

TABLE13.1PercentageofAdultWeightReachedat16WeeksofAge

Thereisoneoutstandingbreeddifferenceinrateofmaturation:thecockerspanielsasabreedareconsiderablyaheadoftheotherfour,havingalreadygained70to72percentoftheiradultweight.

TheshapeofthecurvesinFigure13.4indicatesthatthedogshavenotquitereachedtheirmaximumweightat52weeksofage.The

16

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Ik..13.3.—Maleandfemalegrowthcurvesinbasenjis(above)andcockerspaniels[bilow).

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0510163452

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Fig.13.4.—Growthcurvesofthefivepurebreeds.Above,males;below,females.

331


situationissomewhatcomplicatedbyestrusinthefemales,sinceanon-pregnant

situationissomewhatcomplicatedbyestrusinthefemales,sinceanon-pregnantfemalemaytemporarilygainweightasasymptomofpseudopregnancy,acommonoccurrenceinunmatedfemales.Thismayaccountfortheapparentdiscrepancyin{hefemalebasenjicurve,sinceallfemalesofthisbreedcomeintoestrusaround10monthsofage.

Differentiationofindividualdifferences.—Whenwecomparetheweightcurvesofmalesandfemales,weseethatthereisverylittledifferenceinsizeatbirth,andthattheybecomemoreandmoreunlikeastheygrowolder.This,however,ismoreamatterofchangeinabsolutethaninrelativesize,forifweanalyzethevariationofeithersexwithinabreed,thestandarddeviation,astatisticalmeasureofvariability,fansoutlikeafunnelastheanimalsgrowolder(Fig.13.2).Theupperandlowerrangesofindividualgrowthspreadoutevenfurther.Initialdifferencesinsizebecomegreaterandgreaterastheanimalsgrow,andindividualsthusbecomeincreasinglydifferentiatedfromeachother.

Canwetakethedifferentiationofgrowthcurvesasamodelforthedifferentiationofbehavioraldifferences?Theansweristhatthemodelfitsinsomewaysbutnotinothers.Theprocessofgrowthhascertainsimilaritiestotheprocessoflearning.Growthisanac-cretionaryprocess,inwhichanimalsbecomelargerbyaddingsmallamountseverydaytothatwhichtheyalreadyhave.Insomerespectslearningislikegrowth,especiallywhensmallbitsofinformationaregraduallyaddedtowhathasbeenlearnedbefore.Forexample,achild'slearningnewwordsisverymuchlikeagrowthprocess.However,theprocessofbehavioraladaptationisinsomewaysmuchmorecomplexthangrowth,beingcomplicatedbytheabilitytomakesuddenjumpsorreversalsinunderstanding,andbythecapacitytoadapttoauniformsituationinavarietyofways.Furthermore,whileanimalsmaybecomeincreasinglydifferentincertainbehavioraltraits,theymaybecomemorealikeinothers.

Thepartialresemblancebetweengrowthprocessesandlearninghasmoreimportancethanasimpleanalogy,foroneofthewaysinwhichhereditymayaffectbehavioristhroughgrowthitself.Aswesawinchapter6,sizehasadefiniteeffectonthedevelopmentofdominancerelationships.Howimportantsucheffectsmaybeisaquestionoffact,andthefactswehavearegiveninthefollowingpages.

PHYSICALDIFFERENCES333

THERELATIONSHIPBETWEENPHYSICALDIFFERENCESANDBEHAVIOR

BEHAVIOR

Therecanbenodoubtthatphysicaldifferencescanaffectbehavior.Whendifferencesareextreme,thisstatementhardlyrequiresscientificproof.Theshort-leggeddachshundrunsmoreslowlythanthelong-leggedgreyhound,andthetinyChihuahuaisunabletoclimbuponachair.Thebasicscientificproblemhereiswhetherornotphysicaltraitsalwayshaveaneffectonbehavior,andvarioustheorieshavebeenproposedconcerningthis.Oneisthetheoryofpleiotropy,ormanifoldeffects.Instudyingthegeneticsofthefruitfly,researchworkersdiscoveredmanycasesinwhichtherewasonemajoreffectofageneandmanyminorones.Forexample,Dobzhan-sky(1927)andSchwab(1940)studiedtheeffectsofvariousmutantgenesontheshapeofthespermatheca,oneofthepartsofthefruitflyskeleton.Bothcametotheconclusionthatthemajority,butnotall,ofthegenestestedhadanimportanteffectonthespermatheca.Fromsuchfactsseveralpossiblehypothesescanbedrawn.Atoneextremeisthehypothesisthateverygenewillhavesomeeffectuponeveryprocessinthebody.Thelogicbehindthisisthatanygeneispresentinthebodythroughoutlifefromthemomentofconceptionandthushastheopportunitytoaffectalllifeprocesses.

Attheoppositeextremewecanstatethehypothesisthateachgeneproducesonespecificprimaryeffectandthatpleiotropy,ormultipleaction,isdirectlyrelatedtoprimarygeneaction.Incaseswhereprimarygeneactioniswellknown,asinthesynthesisofvariouschemicalsnecessaryforlifeinthemoldNeurosporaandinbacteria,theusualsituationisalongchainofchemicalreactions,onegenebeingnecessaryforeachreaction(Beadle,1945).Thegenecanbethoughtofasoneelementinageneticcodewhosefunctionistotransferinformationtoabiochemicalsystem.Achangeinagenewhoseactivitytakesplaceearlyintheprocessmayaffectallthesubsequentparts,andmodificationofthisbiochemicalsystemmayaffectothersystemsdependentuponit,butalleffectsaretraceabletoasingleprimaryeffect.

Totakeanotherexample,basedonembryonicdevelopmentratherthanbiochemistry:thedominantgenewhichinahomozygoteproducesthedeformedpolydactylousmonsterintheguineapigaffectsalmosteverypartofthebodywithsuchseveritythattheaffectedanimalscannotsurvivebeyondbirth(Scott,1937).However,alltheseeffectscanbetracedbacktoanaccelerationofgrowthfor

afewdavsinaparticularstageofearlvdevelopment.Alltheorgansgrowingrapidl\'atthattimeareaffected.ThusthemanyactionsofthisgenecanbetracedbacktoasingleprimaryeffeI

Thesetwotheoriesarenotnecessarilymutuallyexclusive.Theremaybecertaingeneswhichhaveeffectsonallbodyprocessesandotherswhoseeffectsarehighlyspecific.Theprincipaldifferencebetweenthetwohypothesesisapracticalone.Thefirsthypotlassumesthattheinheritanceofbehaviorwillbeaffectedbyeverygeneaffectingaphysicaltrait.Thiswouldmakethestudyofbehavioralhereditvmuchsimplerbecausethecon:uldalsobetrue,andeven-beha\ioraldifferencewouldhaveanassociatedphysicaldifferencewhichcouldbeusedasamarker(Keeler.1942Ontheotherhand,ifthesecondhypothesisiscorrect,therewillbemanygenesaffectingphvsicaltraitswhichhavelittleornoeffectonbehavior.Likeanvbehavioraleffectscouldoccurwithoutvisiblechangesinformorshape.Nowletusexaminesomeoftheevidenceasitemergedfromourdogexperiment.

Theeffectofhairlengthonbehavior.—Hairlengthisacommonvariabletraitindogsandshorthairusuallyhasbeenreportedtobeinheritedasaclear-cutdominant(Dawson1937Cockerspanielsareuniformlylong-haireddogs,andanimalsbredfortheshowringaredeliberatelyselectedforlonghair,particularlyonthelegs.Ontheotherhand,basenjisareuniformlyshort-haireddogmeas-

uredthelengthofthehaironthebackbetweentheshoulderbladesofallanimalsatoneyearofage.AscanbeseenfromFiguretheresultsshowconsiderablevariabilitywithinthepurebreeds,andparticularlywithinthelong-hairedcockerspaniels.Partofthisvariabilityisproducedbvsheddingthehaircoat.Onecangetconsiderabledifferencesinmeasuringthesameanimal,dependingonwhetherthecoatismeasuredatitsmaximumlengthorshortlyaftersheddinghasbegun.Nevertheless,theshortesthairedcockerspanielshadcoatsatleastacentimeterlongerthanthelongesthairedbasen-

Thepictureisalsocomplicatedbythefactthatmalestendtohavelongerhairthanfemales,particularlyinthelong-hairedcockerspan-ThisistruealsointhewildCanidae.wherethemalesdevelopalongerruffthanthefemales.

TheF:'softhecockerspaniel-basenjicrossturnedoutverymuchasenjisexceptthatafewindividualshadslighdylongerhair.Ontheotherhand,therewasonlv

thatafewindividualshadslighdylongerhair.Ontheotherhand,therewasonlvonecaseofoverlapbetwee:andcockerspaniels,thatofoneF:malewiththesamehairlengthasacockerspanielfemale.Therewasnooverlapbetweenlike-

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PHYSICALDIFFERENCES

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BASENJI(29)

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Fig.13.5.—Inheritanceofhairlength.Asingledominantgenewillaccountfor

Fig.13.5.—Inheritanceofhairlength.Asingledominantgenewillaccountformostoftheobservedvariation,althoughthereareprobablymodifyinggenespresentinthecockerbreed.Hairlengthwasmeasuredonthebackbetweentheshoulderblades.

individuals.Usingtheserelationshipsasaguide,weclassifiedtheanimalsintheotherhybridpopulations.Inthebackcrosstothecockerspanielstherewere14long-hairedand14short-haireddogs,correspondingexactlytotheexpected50-50ratio.IntheF2generationtherewere16long-haireddogsand57short-hairedones,correspondingquitecloselytotheexpectedratioof18.25to55.75.Weconcludedthatthedatastronglysupportedthefindingsofotherauthorsthattheinheritanceofhairlengthisdeterminedbyasingle


geneinwhichshorthairisdominantoverlonghair.Asindicatedabove,therecessivegenemayhavesomeeffectintheheterozygote,afewF*'sbeinglongerhairedthantheirbasenjiparents,andthereisalsoanindicationthatothergeneshavingaminoreffectonhairlengtharepresent,sincenoneofthelong-hairedcockerbackcrossesdevelopedcoatsaslongassomeofthepurebredcockers.

Thisgaveustheopportunitytoseewhethershorthairhadanyeffectonbehavior.Wehadstrongapriorireasonsforsupposingthatitwoulddoso,sinceashort-haireddogisobviouslymoreaffectedbycoldandlessprotectedagainstphysicalinjurythanalong-hairedone.Wethereforeexaminedtherecordsoflong-andshort-haireddogsinthebackcrossandF2generationsinrelationtothe10physicalmeasurementsand40behavioralmeasurementswhichBrace(1961)hadusedinhisfactoranalysis.

Inassessingsuchresults,onehastorememberthatdifferencescanoccursimplybychancewhenfinitenumbersareused.Wewouldexpectthatatleastonedifferenceoutof20wouldbestatisticallysignificantatthe.05levelsimplyasamatterofchance.In50variableschosenatrandom,weoughttogetontheaverage,2.5suchresultspurelybychance.Ontheotherhand,ifthereisarealandimportanteffectofthegene,weshouldgetmorethanthisnumberofsignificantdifferences,andthedifferencesshouldbeinthesamedirectioninthetwohybridpopulations.Afurthertestwouldbewhetherareasonablemechanismcouldbehypothesizedfortheobservedeffect.

Amongthebehaviorvariablestherewasonesignificantdifferenceinthe

Amongthebehaviorvariablestherewasonesignificantdifferenceinthebackcrosspopulation,intheobediencetest.However,thedifferenceinthesametestintheF2generationwasintheoppositedirectionandnotsignificant,andweconcludedthatthisapparentdifferencewasduetoanaccidentofsampling.AmongtheFYs,whichwehadinlargernumbers,thereweretwosignificantdifferences(Fig.13.6).Oneoftheseagainshowedanoppositedifferenceinthebackcrossgenerationandwasprobablyaccidental.However,therewasonehighlysignificantdifference,intheconfinementtest.Althoughthedifferencewasnotsignificantinthebackcross,itwasfairlylargeandinthesamedirection.Intheconfinementtest,thedogsinalitterwereconfinedoutdoorsinsmallwire-bottomedpensandgradedonallformsofactivitywhilealittermatewasremoved,handled,andfed.Theresultsindicatedthatshort-haireddogsweremoreactiveunderthesecircumstancesthanlong-haireddogs,whichisareasonableconclusion,becausetheshort-haireddogswould


havebeenconsiderablylesscomfortableincoldweather.Thisappearstobearealeffectofaphysicaltraitonbehavior.

Wealsocomparedthelong-andshort-haireddogsontheirphysicalmeasurements.Thelong-haireddogsaveragedlargerineverymeasurementinbothbackcrossandF2generations.Allthedifferenceswereinthesamedirection,butonlyoneofthesewasstatisticallysignificant.Sucharesultcouldbeeasilyexplainedbythefactthatallthemeasurementsweremadewithoutshavingthedogs,andthusthemeasurementsoflong-hairedanimalswouldbeslightlylarger,eveninthecaseofbodyweight.Anotherpossibilitymighthavebeenthattherewereaccidentallymoremalesinonegroupthananother,malesbeingbothlargerandhavinglongerhair.This

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Fig.13.6.—Distribution(instanines)ofdifferencesbetweenlong-andshort-coatedanimalsinrelationto34behavioralvariables(omittingthoseconfinedto2categories).Arrowsindicateapproximatestandarderrorofthedifferenceformostvariables.Longorshorthairhaslittleeffectonbehavior.

wasnotthecaseintheF2generation,inwhichmalesandfemaleswerealmostevenlydistributed.Wecanconcludethatlonghairmaypossiblyhaveaneffectonsizemeasurements,butifsoitisprobablyanartificialoneresultingfromslightlylessaccuratemeasurementofthelong-haireddogs.Inanycase,theeffectisnotanimportantone.

Despitethesenegativeresults,thereisnodoubtthatlonghairmayhaveaneffectonbehaviorinspecialsituations;e.g.,ashort-haireddogwillhesitatetositdownonsnoworice.Theexperimentdemonstratesthatthereisnoimportantgeneraleffectofthegeneforshorthairuponbehavior.Ifitistruethateverygeneaffectsallactivitiesofthebody,theeffectsofthisgenemustbesosmallastohavelittle,ifany,importanceandinfactbeunmeasurable.The


resultsupportsthesecondhypothesis,thatofspecificprimarygeneaction.

Theeffectofhaircoloronbehavior.—Whilewewereconductingourexperiments,Dr.C.C.Little(1957)wasmakingextensivebreedingteststodeterminetheinheritanceofcolorinalargenumberofbreeds,includingthoseusedinthebehavioralexperiments.Whilevariouscolorsarepermittedbythebasenjibreedstandards,theanimalsofourstrainwereallpureredasadults(exceptforwhitespotting),butthepuppieswerealwaysbornwithblackhairsmixedwiththered,theblackbeinglostatabout5or6weeksofage.

Crosseswithotherbreedsestablishedthefactthatthiscolorisproducedbythesamegeneasthatwhichproducesthecolorcommonlycalled"sable"incollies,whoselonghairisreddishoryellowishatthebaseandblackatthetips.Modifyinggenesinbasenjiscausetheblacktipstobelostinadults.

Thegeneavwhichproducestheredcolorinbasenjisisanintermediatememberofanallelomorphicseries,themostdominantgenebeingAs,agenewhichproducesasolidblackcolor,andtheleastdominantbeinga\producingblackwithreddishortanpoints.Whilesomeofthecockerswerered,thiswastheeffectofanotherrecessivegene,e,whichproducesaclearredcolorwithnoblackatanytimeinlife.

blackatanytimeinlife.

Consequently,thebasenjishadthegeneticconstitutionayay,thecockersA"A8,andtheFi's,A*av.BackcrossingtheFi'stobasenjisgavetwocolorsinapproximatelyequalnumbers:black(AW)andred(ayay).Thisgaveanopportunitytocomparethebehaviorandphysiqueoftwogroupsofanimals,onehavingthegeneA*andonewithoutit.

Thisanalysisgavenostatisticallysignificantdifferencesinanyofthephysicalvariables,althoughthegroupofredsaveragedslightlylargerthantheblacksonmostmeasurements.Thisresultwasprobablyaccidental.Therewasonesignificantdifferenceinthebehavioralvariables(P=.05),butthesametestintheF-populationshowedadifferenceintheoppositedirection,andnotsignificant.WemayconcludethatthereisnogeneralpleiotropiceffectproducedbythegeneA8.

Thisdocsnotmeanthatitisimpossibleforcolorgenestohaveeffectsonbehavior.Thereisacolormutationinthehousemousewhichitsdiscoverernamed"varitintwaddler"(CloudmanandBunker,1945).Thisanimalhasapeculiarmulticoloredspottingcombinedwithalimpinggaitresultingfromsomedefectinthenervoussystem.Likewise,the"merle"gene,foundinseveraldog


breeds,hastheeffectofchangingblackcolortoalightgraywithblackspots.Thiscolorismuchadmiredamongthefancy,particularlyinshelties,andisproducedbyadominantgene,M.Homozy-gotesareproducedwhicharealmostpurewhiteandoftenhavedefectiveeyesandears.Thesedefectivesenseorgans,ofcourse,causedifferencesofbehavior.Werearedonesuchanimalinourtestingprogram.Ithadsmalleyes,oneofthembeingalmostcompletelysightless,sothatitdidnotrespondtovisiononthatside.Itwasalsodeaf,butthisseemedtohavetheeffectofmakingitlesseasilydistracted,sothatinmanytestsitactuallydidbetterthannormalanimals.

Sincethepigmentcellsoriginateinembryonicdevelopmentfromthecrestoftheneuraltube,itislikelythattheprimaryeffectofthegeneistoalterthedevelopmentoftheneuraltubeandrelatedsenseorgans,thisinturnaffectingthedistributionoftheneuralcrestcellswhicheventuallyproducepigment.

Wecanconcludefromthesedatathatatleastsomecolorgeneshavenodemonstrableeffectonbehavior.Althoughcertainothercolorgenesmayhave

demonstrableeffectonbehavior.Althoughcertainothercolorgenesmayhaveeffectsonbehavior,theseeffectsareassociatedwithdefectsinthedevelopmentofthenervoussystem.

Theeffectsofbodysizeandproportionsonbehavior.—Physicalbuildandbehaviorhavelongbeensupposedtobeassociated.Accordingtotradition,fatpeoplearejolly,thinpeoplearesouranddyspeptic,andheavilymuscledmenarequicktoanger.ThemostambitiousattempttoinvestigatethistraditionwasundertakenbyW.H.Sheldon,whodevelopedatechniqueforestimatingbodyproportionswhichhasbeenwidelyusedinanthropologyandbydepartmentsofphysicaleducation.Sheldonmeasuredthebodyintermsofthreecomponents,eachmeasuredona7-pointscale.Thefirst,endomorphy,isbasedontheamountofbodyfat.Thesecond,ormesomorphy,isameasureofheavybonesandmuscles;andthethird,ectomorphy,isthetendencytohaveahighproportionofskin(actually,tobethin)withlightbonesandmuscles.Thetechniqueofmeasuringbodytypes,orsomatotypes,inthiswayistotakephotographsofthenudebodyinstandardpositions,blackingoutthefaceforreasonsofanonymity.Thebodytypeisthenestablishedona7-pointratingscaleforeachcharacteristic.

Sheldon'stechniquecanbecriticizedonthegroundsofbothsubjectivityandlogic(Hammond,1957).Theaccuracyofthescalesdependsagreatdealontheexperienceandskillofthepersonusingthem.Therearelogicallyonlytwoindependentcomponents,sinceectomorphyisessentiallyanabsenceoftheothertwo.Howells


(1952)hasshownbyafactorialanalysisofnumericalmeasurementsmadeofmendesignatedasextremesomatotypes,thatthereisactuallyonlyonescale,endomorphy-ectomorphy,andonecomponent,fat,thatcanberelatedtoSheldon'ssystem.However,thechiefinteresttousliesinthefactthatSheldonandStevens(1942),onthebasisofmanycasehistories,statedthattheyfoundacorrelationbetweensomatotypeandtemperament.Aswehavesaidbefore,physiqueobviouslyaffectsbehavior.Aboywithstrong,heavymuscles,forexample,ismorelikelytoenterasportlikefootballorboxingthanaboywithslightandwirybuild.SheldonandStevenswentbeyondthis,implyingthatthesamefactorswhichproducedphysicalbuildaffectedbehaviorindependently,producingtraitswhichhadnothingtododirectlywithphysicalbuild.Thisisessentiallythesametheoryofgeneralpleiotropywhichwehavediscussed

essentiallythesametheoryofgeneralpleiotropywhichwehavediscussedbefore.

Ourlong-termexperimentwithdogsseemedlikeanidealopportunitytotestSheldon'stheoryoftheeffectsofsomatotypesonbehavior.CharlesShade,oftheHarvardUniversityDepartmentofPhysicalAnthropology,spentasummerdevisingasystemformakingbodymeasurementsondogs.HefoundfirstofallthatSheldon'ssystemofphotographswasimpracticalwithdogs,sincethefurmakessomuchdifferenceinphysicalappearance.Everyanimalwouldhavetobeshavedforthissystemtowork.Furthermore,itseemeddesirabletotrytoimproveonSheldon'ssystemanddevisemoreobjectivemeasurements.Shadefinallydevelopedaseriesofsevengeneralmeasurementswhichcouldbedonewithreasonableaccuracy,andwelateraddedthreespecialmeasuresofboneandmusclesizetomakeatotaloften.

Thefirsttwoofthesewereover-allmeasurementsofbodysize:weight,andbodylengthfromtheanteriorendofthebreastbonetotheposteriorpointofthehips.Theaccuracyofthislastmeasuredependedonbeingabletogetthedogtostandwithitsbodyinastraightlineandinanaturalposition.Thentherewerethreemeasurementsofthechestregionofthebody:brisketdepth(measuringthechestfromtoptobottom),chestbreadth,andchestcircumference.Theabdominalregionwasmeasuredbywaistcircumference.Heavinessofbonewasmeasuredbytakingthediametersofthefemurandhumerus,thelargebonesofthehind-andforelimbs.Heavinessofmuscleswasmeasuredbytakingthecircumferencearoundthethigh,thusmeasuringoneofthelargestmusclegroupsinthebody.Finally,leglengthwastakenbymeasuringthestandingheightattheshoulder.Thus,ifthereweredogswithunusual

PHYSICALDIFFERENCES

341

70

6.5

6.0

iii

z

25.0m

4.54.03.5

humerusdiam.

waist

thighchestdepthfsmurdiam

bodylengttichestbreodth-humsrusdlam^'

tailr'

/Vheight/Awolstc.

thighc.bodylength

chestc.femurdiam.chestbreadth

height

height

f

BA

3.03.54.04.55.05.5

WEIGHT(STANINES)

6.0

6.5

Fig.13.7.—Relativeproportionsofcockerspanielsandbasenjis.Ifthetwobreedshadthesameproportions,allthelineswouldbeparalleltothatofweight.Actually,onlywaistcircumferenceandchestbreadthareapproximatelysimilar.

Ifthebasenjisweresimplythinnerdogs,alllineswouldbeparallelbutrunupwardwithrespecttoweight.Actuallythelinesrunindifferentdirectionsandthemeasurementsoccurindifferentordersinthetwobreeds(rankordercorrelation=—.17).Basenjisarerelativelytaller,andhaveathickerhumerus,deeperchests,andlongerbodiesthanspaniels.

amountsoffat,muscle,orbone,thesemeasurementsshouldreflectsuchtraits.

Webegantakingthefullsetofmeasurementsat17weeksofage,andrepeatedtheseat34and51weeks.Wetookthelastmeasurementstorepresentthefinalphysicalbuildoftheadultdog,andanalyzedtheminvariousways.

Whenwetaketheaverageofeachoneofthesemeasurementsforeachpurebreedandcompareittotheaverageweightofthebreed,wefindthatthereareindeeddifferencesinproportions(Table

DIFFERENTIA!CAPACITIES

13.2).Thesheltiesshowthegreatestnumberofextremedeviationsandcouldbedescribedashavinglargeanddeepchests,thinwaists,smallthighs,smallbones,longbodies,andlonglegs.InmanyrespectsthevcorrespondtotheectomorphsofSheldon'ssomatotvpes.

TABLE13.2

TABLE13.2

RankfromLargest(1)toSmallest(5)inBodyMeasurementsRelativetoWeight,intheFivePureBreeds

Xoneoftheotherbreedsshowssuchextremedeviations.Wire-hairedterriersarethickwaistedandhaveaheavythighandfemur,indicatingthatthevhavelargemusclesandthickboneswhichwouldbeusefultoabreedusedforattack.Theymightbelabeledmeso-morphs.thoughnotofanextremetvpe.Cockersarerelativelysmallchestedandshort-bodiedinproportiontoweight.Beaglesarerela-tivelvbroadchestedandshort-legged,butotherwiseundistin-guished.However,thismayhavebeencausedbyoneofthefoundationmaleshavingtheseproportions,ratherthanbeingcharacteristicofthebreedasawhole.Basenjis,althoughthevhaveadistinctiveappearance,areoutstandingonlvinhavingaheavyhumerus.

Tocomparethetwobreedsusedinthecross,basenjisarelargerinalmosteven-dimensionthancockers,bothinabsolutesizeandsizerelativetoweight.Thislastmeanschieflythatbasenjisarerelativelythinandcockersrelativelvfat.Thetwobreedsaremostdifferentinrespecttoheight;thenextmostimportantdifferencesareinthedepthandsizeofthechest,andbodylength.Thusbasenjisaretall,thin,deepchestedandlong-bodied,whilecockersarerelativelyshort,fat,shallowchestedandshort-bodied.Thediffer-sidproportionarenotextreme,andinSheldon'ssvstemthebasenjiwouldprobablybea'mescctomorph,"andthecockera"mesendomorph."

Aftermeasurementswerecollectedforallhvbridsaswellaspurebreeds,anotherphysicalanthropologist,LoringBrace(1961),began


hisdetailedstudybythemethodoffactorialanalysis.Hefirstconvertedallmeasurementsintostanines.Asdescribedinchapter7,thisisamethodoftenusedinpsychologytoconvertmeasurementsintoaforminwhichtheycanbeeasilyanalyzedbythemethodsofnormalcurvestatistics,includingstandarddeviationsandcorrelationcoefficients.

Bracechose40behavioralmeasurestocomparewiththe10measurementsofphysicalsize,selectingthosewhichseemedtoshowthemostclear-cutbreeddifferencesandindicationsofMendelianinheritance.Someofthesemeasurementscamefromthesametests,butthesewereoneswhichappearedto

measurementscamefromthesametests,butthesewereoneswhichappearedtobeatleastpartiallyindependentofeachother.Therewere13separatebehavioraltestsituationsrepresented.Bracethushad50measurementsoneachdoginfivedifferentpurebreeds,plussixhybridpopulationsbetweenthebasenjisandcockers,asbasicdata.

Factoranalysisisamathematicalmethodbasedoncorrelation.Thelogicbehinditsusewasthatiftherewereseveraldifferentbehaviortraitsorphysicalmeasurementsaffectedbythesamegenesorgroupofsimilargenes,theneachtraitshouldbecorrelatedwithalltheothers,appearingtogetherinthesameanimalandbeingmeasurablebycorrelationcoefficients.Themethoditselfisdesignedtosortoutgroupsofmeasurementswhichhaveacommoncorrelation,andthepresumedcausebehindsuchagroupiscalledafactor.IfthereisanytruthinSheldon'scontentionthatsomatotypeisrelatedtobehavior,weshouldgetfactorsincludingbothphysicalmeasurementsandbehavioralmeasurements.

Thefirstmathematicalstepwastocorrelateeachofthe50variableswitheachotherone.Thismeantcalculatingatotalof1,225correlationcoefficients,alongwiththemeansandstandarddeviationsforeachmeasurement.Bracedecidedtocalculatesuchtablesforeachbreedandhybridpopulation,andbyusingmoderncalculatingmachines,hewasabletocalculate50X50correlationtableson16differentpopulationsofanimalsinasinglenight'swork.Thismeantatotalof19,600correlationcoefficients.This,however,wasonlythebeginning.Thecommunalityofcorrelationstillhadtobedeterminedbytheprocessofrotation,whichisequallylaborious.This,however,couldbedonebyprogrammingcomputingmachines,andafterseveralmonths'work,Bracewasabletogetthemachinessetupsothattheywoulddothejobaccurately.Insodoing,hewasabletouseamathematicalmethod(thatofprincipalaxes)whichhadhithertobeenimpracticalbecauseofitslaboriousnature.

Wemaynowconsiderfactoranalysisinrelationtogenetics.The


methodisbasedoncorrelation,whichinturnisbasedontheassumptionofadditiveeffectsofcausalfactors.Studiesofgrowthandphysicalsizehavegenerallyindicatedthatgeneticfactorsaffectingsizeareadditive;thatis,eachgenemakestheanimalalittlebigger.Ontheotherhand,aswehaveshowninotherchaptersofthisbook,complicatedinteractionbetweengenesisaverycommonphenomenonaffectingtheexpressionofotherkindsofphysiologicalandbehavioraltraits.Themathematicallogicbehindtheuseofthecorrelation

andbehavioraltraits.Themathematicallogicbehindtheuseofthecorrelationcoefficientassumesthatthesamegenealwaysproducesthesameeffect,andthismaynotbetrueinthecaseofgenesaffectingbehavior.

Assuming,however,thatwecangetgoodadditiveeffects,therearetwowaysinwhichhereditycanproducecorrelationinadditiontothecaseofasinglegene'seffectondifferenttraits.Oneoftheseisthepresenceoftwogenesonthesamechromosome,producingthegeneticphenomenonoflinkage.Theotheristhesimultaneousselectionofseveraldifferenttraitsinasinglebreed.Wewouldexpectthatinanypurebreedtherewouldbeanumberofdifferentgenesbroughttogetherbyselection.Hence,inapopulationofseveralpurebreedswewouldexpecttogetgroupsofartificiallycorrelatedgeneswhichwouldappearinafactoranalysisasbreedfactors.

InsegregatingpopulationssuchasthebackcrossorF2generations,weshouldgetcorrelationsbetweenalloftheeffectsproducedbyeachsegregatinggene,orbyeachgroupofcloselylinkedgenes.TheF2populationwouldprovidethebestopportunityforsuchcorrelationstoshowup,becausetheeffectsofallsegregatinggeneswouldappear,astheymightnotinabackcrosstoadominantparentpopulation.

Wewouldalsoexpecttogetdifferentfactorsinthedifferentsegregatingpopulationsbecauseofdominance,whichwouldcompletelysuppresstheactionofarecessivegeneinabackcrosstoadominant.Thereshould,therefore,befewercommonfactorsbetweenbackcrossesthanbetweenbackcrossesandF2's.

Ontheotherhand,ifwearedealingwithnon-geneticcorrelations,thesamefactorsshouldappearinallpopulations.Wewouldexpectthatatleastsomeofthesenon-geneticfactorswouldturnupbecauseofthefactthatmorethanonemeasurementwastakenfromcertaintests.Somemeasurementscouldbecorrelatedsimplybecausetheycamefromthesametestsandweredoneontheanimalatthesametime.

Thecorrelationbetweenphysicalsizeandbehavior.—TheF2populationprovidesthebestchancefordetectingcorrelationsdue

PHYSICALDIFFERENCES

345

tocommongeneticfactors.Withoutgoingthroughtheentirefactoranalysis,we

tocommongeneticfactors.Withoutgoingthroughtheentirefactoranalysis,wecangetsomeideaoftheeffectofphysicalmeasurementsonbehaviorbysummarizingthecorrelationmatrix(Table13.3).Ininterpretingtheseresults,wemustrememberthatacertainnumberofcorrelationsmayoccursimplybyanaccidentofrandomsampling.Inourpopulationof72F-hybridsthereis1chancein20thatcorrelationslargerthan.23willappearsimplybyaccident.

TABLE13.3

SignificantCorrelationsbetweenPhysicalMeasurementsandBehavioralVariablesinPureBreedsandHybrids

•Correlatedtestsarenotidenticalinthesetwogroups.

ThephysicalmeasurementsintheF2'sareallhighlycorrelatedwitheachother.The45possiblecorrelationsrangefrom.90to.40,withmostofthemtowardthehigherend.Thereisnodoubtthatsizemeasurementsarecorrelatedwitheachother.

Ontheotherhand,thecorrelationsbetweenphysicalandbehavioralmeasurementsareallsmaller,thegreatestonebeing—.36.Eachofthephysicalmeasurementscouldbecorrelatedwiththe40behavioralmeasurementsmerelybychance1timeoutof20,oratotalof2times.The10measurementsshouldthereforeshow20significantcorrelationsmerelybychance,andtheobservednumberis24.Althoughthepossibilityexiststhatsomeofthesearerealcor-


relations,thereisnoevidencethatthereisanystrongorimportanteffectofphysicalsizeonthe40behaviormeasurementschosenforanalysis.

Sincethephysicalmeasurementsarecorrelatedwitheachother,weshouldexpectthemtobecorrelatedwiththesamebehavioralmeasurementswhetherornotthiswasamatterofchance.Thiswasindeedthecase,and18ofthe25significantcorrelationsrelateto4behavioraltests:habit-formation,vocalizationinthereactivitytest,numberoferrorsinthebarriertest,andplayfulaggressivenessinthehandlingtest.Someofthese,likeplayfulaggressiveness,mightreasonablybeeffectsofsizedifferences.However,thelowcorrelationsandthesmallexcessofsignificantcorrelationsbeyondchanceexpectationsleadtotheconclusionthattheeffectsofphysicalsizeonthebehaviortestsareminorones,iftheyexistatall.Inshort,variationinphysicalsizehaslittleifanyeffect

ones,iftheyexistatall.Inshort,variationinphysicalsizehaslittleifanyeffectonthevariationofbehaviorintheF2population.

Whenwelookattheresultsofcorrelatingphysicalandbehavioralvariableswithinthepurebreeds,wegetasomewhatdifferentimpression.AsTable13.3shows,thebasenjisshowslightlymorethan

TABLE13.4

FactorLoadingsofPhysicalVariablesinCombinedFaPopulation,PrincipalAxisRotation*

Theloadingsindicatetherelativeefficiencyofeachvariablea?ameasureofgeneralsizeandfallinto4groups.

the

expectednumberofsignificantdefinitelyless.Theotherthree

correlationsandthebeaglesvbreedseachshowtwicetheexpectednumberofsignificantcorrelations.Withincertainofthepurebreeds,itlooksasifphysicalsizemighthavesomeeffectonbehavior.


Suchcorrelationsmightinpartbecausedbythefactthatthephysicalmeasurementsthemselvesarecorrelated.Wecantestthispossibilitybyexaminingthesampleofphysicalmeasurementsindependently.Actually,anyoneofthephysicalmeasurementsshowsmorethanthenumberofcorrelationsexpectedbychance.Thereisthusastrongpossibilitythatphysicalsizehasanimportanteffectonbehavioragainstthegeneticbackgroundspeculiartocertainbreeds.Adifferenceinsizemightbeexpectedtoproducearelativelyconsistenteffectonanimalsshowingsimilarbehaviorandthusshowupasacorrelation.However,analternateexplanationoftheresultsmightbethatthereareindividualsorstrainswithinapurebreedinwhichphysicalmeasurementsandbehavioralmeasurementsareaccidentallycorrelated,andthispossibilitycannotbeentirelyruledoutbythedata.

Relationshipsbetweenthephysicalvariables.—ThefactorloadingsintheF2populations(Table13.4)showhoweachmeasurementisrelatedtogeneralsize.Weighthasthehighestloading,followedbythethreemeasuresofcircumference,withalllinearmeasuresfallingbelowthese.Thisisareasonable

circumference,withalllinearmeasuresfallingbelowthese.Thisisareasonableresult,sinceweightcombinesalldimensionsofthebody,acircumferencecombinestwo,andalinearmeasurementonlyone.

Theloadingsthusfallintofourgroupsrelativetoeachother.Bodyweightandchestcircumferencehavethehighestloadingsonthegeneralsizefactor,formingthefirstgroup.Bodyweightmeasurestheentiresize,whereaschestcircumferencemeasuresthesizeofthethorax,thelargestpartofthedog'sbody,whichincludesmanyofhisinternalorganssuchastheheart,lungs,liver,etc.Inthenextgrouparethighcircumference,whichmeasuresthesizeofthehindlimb,andwaistcircumference,whichmeasuresthesizeoftheabdominalregion.Inthethirdgrouparefivemeasurementswhichhavealmostidenticalfactorloadings.Thetwochestmeasurementsarehighestandthetwobonemeasurementsthelowest.Finally,standingheight,whichmeasuresthelengthoftheforelimb,fallsintoagroupbyitself,withaverylowloadingcomparedtotherest.

Thefactoranalysisindicatesthatanymeasureofthebodyisstronglyrelatedtogeneralsize,andthusthatallthedogsintheFl»populationhavemuchthesameproportions.Theonlyexceptionisthemeasureofheight,whichmaybedisproportionatetotherest.Thereisnoindicationofdisproportioninanyspecialtissues,suchasfat,bone,ormuscle,inthispopulation.

Generalresultsofthefactoranalysis.—Braceusedtwomethodsoffactoranalysisoneachpopulation.Theprincipalaxismethodisthe


idealmathematicalmethod(Thurstone,1947)andproducesagroupofmeasurementsrelatedbycommoncorrelationandweightedaccordingtotheimportanceofeach.Thisweighting,orfactorloading,canbeeitherpositiveornegative,andcanvaryfromzerotoone.Becausesomanymeasurementsappearineachfactor,theresultsaresometimeshardtointerpret.Thevarimaxmethod(Kaiser,1958)isusedtoemphasizethosemeasurementshavingthelargesteffectandtoeliminatetheunimportantones,andsoaidintheinterpretationofthefactors.Onlytheresultsoftheprincipalaxismethodareconsideredhere.

Aswestatedabove,theF2'sprovidethecriticaltestofthehypothesisthatphysicalmeasurementsareassociatedwithbehavior,sinceinthispopulationgeneticvariationshouldoccurfreelyinallrespects,withaminimumamountofcorrelationduetolinkageandaminimumeffectofdominance.Aswemight

correlationduetolinkageandaminimumeffectofdominance.Aswemightexpectfromthebasiccorrelationtable,onlyonebehavioralmeasurehasaloadingofanyappreciableimportanceonthegeneral-sizefactor.Goodperformanceonrunningtoagoalinthehabit-formationtestisweaklyassociatedwithlargesize(.29).Thisisareasonableeffect,butsosmallthatitmaywellbeaccidental.Furthermore,noneofthephysicalmeasurementshaveloadingsonanyoftheotherfourbehavioralfactors.Wecanonlyconcludethatthephysicalmeasurementshavenoimportantconnectionwithbehaviorinthecrossbetweenthesetwobreeds.

TABLE13.5

FactorLoadingsofFactor1(GeneralSize)inCombinedPureBreeds(N=100)

Variables

Physical:

Chestcircumference

Brisketdepth

Weight

Bodylength

Standingheight

Humerusdiameter

Waistcircumference

Thighcircumference

Chestbreadth

Femurdiameter

Behavioral:

Fewerrors,U-shapedbarrier

Fastspeed,longbarrier

Fewerrors,longbarrier

Fewnoises,U-shapedbarrier

Success,manipulation,stringpulling

Success,manipulation,movingbox..

Fastspeed,maze

Activewhileweighed

FactorLoading

.88.87.77.76.74.73.73.71.65.64

.48.44.43.37.36.36.35.30

PHYSICALDIFFERENCES

349

Whenwelookattheotherpopulations,wefindthatineveryonethephysicalvariablesarestronglycorrelatedandthatthefactoranalysisconsequentlyassignsthemhighloadingsonafactorofgeneralsize.Thesegregatingpopulationsareofparticularinterestindeterminingtherelationshipofthisfactortobehavior.Intheback-crosstothecocker,theheartrate—bothofpuppiesandadults—isassociatedwithsize,largedogshavingaslowerrate.Thesamethingistrueinthebackcrosstothebasenji,butthiseffectdoesnotappearintheF2S.Themostlogicalexplanationisthatitisaneffectoflinkageupontwotraits,neitherofwhichisaffectedbydominance.Inthebackcrosstothebasenji,therearethreeotherbehavioralvariablesassociatedwithsize,buttheloadingsarelowandlackalogicalexplanation.Theselastresultsarethereforeprobablyaccidental.

Incontrasttodiesegregatinghybrids,thepurebreeds,bothtogetherandseparately,showalargenumberofbehavioralvariablesassociatedwithsize(Tables13.5and13.6).Theseseemtobedifferentineverybreed,andthevarimaxrotationhaslittleeffectuponthem.Itlooksasifsizemayhaveaneffectonthebehaviorofanimalswhicharesimilartoeachotherotherwise,butthatthe

onthebehaviorofanimalswhicharesimilartoeachotherotherwise,butthattheeffectsarenotconsistent.Inotherwords,sizedoesnotproducethesameeffectonthebehaviorofasheltieasitdoesonthatofafoxterrier.

TABLE13.6

FactorLoadingsofFactor1(GeneralSize)inShetlandSheepDogsandFoxTerriers

Variables

Physical:

Chestcircumference

Femurdiameter

Brisketdepth

Weight

Chestbreadth

Humerusdiameter

Waistcircumference

Bodylength

Thighcircumference

Standingheight

Behavioral:

Manipulation,movingbox,success..

Manipulation,stringpulling,success

Littlevocalization,leashcontrol

Littlevocalization,reactivity

Muchvocalization,U-shapedbarrier

Fightingleash

Activeinconfinement

Obedience,littledocility

Fewerrors,longbarriertest

FoxTerriers


Ofcourse,itmaybethatthesecorrelationsareproducedbyaccidentalassociationofsizeandtemperamentamongtheoffspringofdifferentmatingswithinthesamebreed.Thispossibilitycanbetestedbycomparingtheresultsofreciprocalcrossesbetweenthetwobreeds,sincetheparentsinacrossbetweenmalebasenjisandfemalecockersarenecessarilydifferentindividualsfromthoseinthereversecross.InthetwoFipopulationsthereare13behaviortestswhichhavemoderatelyhighloadingsonfactor1.Ofthese,onlytwoarefoundinbothpopulations.Thiswouldmeanthatmostoftheapparenteffectsofphysiqueonbehaviorareprobablycausedbyaccidentalassociationbutthatsomeeffectsmaybereal.

TheseresultscorrespondtothoseofHumphreyandWarner(1934),whocorrelated42measuresofphysiquewith9measuresofbehaviorwithintheGermanshepherdbreed.Theyobtainedonly15correlationsoutofapossible378.Themostthatwecansayisthatthereisapossibilitythatsizehasvaryingeffectsonbehaviordependingonthegeneticconstitutionoftheindividualinvolved,butthatthisisatpresentonlyaninterestinghypothesis.

Withregardtotheotherresultsofthefactoranalysis,onebasichypothesistobetestedwasthattherewereafewbasicgenetictraitsofbehaviorwhichmightaffecttheresultsofmanydifferenttestsandsorunthroughthewholelifeofananimal.Ifsuchtraitsrepresentedtheactionofdifferentgenes,thenonewouldexpecttogetdifferentfactorsindifferentpopulations,dependingbothonthepresenceorabsenceofthesegenesandalsoupontheirmaskingbydominance.Insteadofthis,Bracegottheoppositeresult:muchthesamefactorsappearedineverypopulation.Therewasonefactoremphasizingphysicalmeasurements,anotheremphasizingphysiologicalmeasurements,andtwootherswhich

anotheremphasizingphysiologicalmeasurements,andtwootherswhichincludedbehaviormeasurements.Ofthelatter,oneincludedmostoftheperformancetests,andtheotherwasstronglyrelatedtotestsofemotionalreactivity.

Allthissuggeststhatsimilarkindsofbehaviorandphysiologicalactivityarecloselyrelatedonlytothemselves.Hereagainthedatadisagreewiththetypeconcept;thebehaviorofananimalinonesituationisnot"typical"forhisbehaviorinanothersituation.Amoredetailedstudyofthebehavioralaspectsofthefactoranalysiswillbegiveninanotherchapter.

Thustheresultsofthisexperimentarealmostcompletelynegativewithregardtothehypothesisthata"somatotvpe"isstronglycorrelatedwithtemperamentandbehavior.Itcan,ofcourse,bearguedthatsucheffectsmightappearinacrossbetweentwobreedscontrastingmoresharplyinphysicalbuildthandocockersandbasenjis.


However,therearegoodtheoreticalreasonsforbelievingthatgeneticfactorsaffectingbodybuildandbehaviorarelargelyindependentofeachother.

Evaluationofthesomatotypeconcept.—Wecanmakeabasictheoreticalcriticismofthesomatotypeapproachtobodybuildandbehavioronthegroundthatitrepresentsaprimitiveandnowalmostdiscardedmethodofbiologicalstudy.Thetypingmethodwasusedbytheearlynaturalistsintheirdescriptionofanimalspecies.Theyfirstselectedanindividualforverycarefuldescriptionandcalledthisthe"type"ofthespecies.Oftentheindividualwasselectedonthebasisofintuitionorsimplybecauseitwasavailable.Thentheyattemptedtodescribethespeciesasawholeascomparedtotheindividual"type."Thismethodhasobviousdrawbacks,anditresultedintheartificialcreationofmanyspecieswhichdidnotexistinnatureandwerelatershowntobepartofthesamepopulation.

Thetypingmethodcangiveaverymisleadingpictureofapopulation.Forexample,thetypespecimenselectedforNeanderthalmanturnedouttobeanoldmanprobablysufferingfromarthritis,withknobbybonesandstoopingposture.LatercollectionsofotherspecimensshowthatmanyNeanderthalskeletonsareindistinguishablefromthoseofmodern-dayEuropeans(Brace,1962).

Themodernapproachofnaturalistsistomeasureanddescribethepopulation

Themodernapproachofnaturalistsistomeasureanddescribethepopulationfirstandthentodescribetheindividualintermsofthepopulation.Thismeansthecollectionofmeasurementsonareasonablylargesampleofthepopulation,fromwhichestimatesoftheaverage,standarddeviationandvariancecanbemade.Inthisexperimentwehaveusedthepopulationmethod,butinsuchawaythattypescanberecognizediftheydoinfactexist.Ifapopulationisdividedintofourorfivetypesinsteadofshowingcontinuousvariation,weshouldgetclustersofcorrelatedtraitsbythefactor-analysismethod.Ifphysicaltypeisassociatedwithbehavioraltype,thensomephysicalmeasurementsshouldbeassociatedinonegroupbythemselves,withdifferentsetsofphysicalmeasurementsinothergroups.Thisdidnothappeninthefactoranalysis,andhencealltheevidencewhichwehavecollectedisagainsttheexistenceofsuchtypes.

Dogbreeders,inchangingandimprovingtheirbreeds,haveusedthetypemethod,selectinganindividualasagrandchampionandthenattemptingtobreedforthisparticulartype.Ifthecharacteristicsofanindividualareinfactproducedbyalargenumberofvariablegenes,producingauniformtypeshouldbeanextremelydifficulttask,asthedogbreedershaveindeedfound.Muchvari-


abilityremainsineverybreed.However,thebreedshavetosomeextentbeenstandardizedbyselection,andwhenthecombinedpurebreedsareanalyzedbythefactor-analysismethod,thereshouldconsequentlyappearcertainfactorswhichcorrespondtothegroupoftraitspeculiartothe"type"ofeachbreed.Asindicatedabove,thiswasnotthecase,andwemustconcludethattheassociationoftraitsproducedbyselectionforatypeisquiteweak.

Theearlygeneticistsalsousedthetypeconceptindescribingmutationsand,infact,didnotevenbothertostudyhereditaryvariationunlesstheyfoundagenewhichproducedaclear-cut"pheno-type."Aswithtaxonomists,themoderntendencyistousethepopulationapproach,butthetypeconceptmaystillbeusefulindescribingcertainextremetraitsorcombinationsoftraits.

Thisbringsusdowntotheunderlyingtheoryofgeneticeffectsonadultcharacteristics.Allourevidenceisconsistentwiththehypothesisofspecificprimaryeffectsofgenes.Whilepleiotropymayexist,itcertainlydoesnothaveuniversalimportance.Typingmaybeusedtodescribetheeffectsofasinglegenewhichhaseitherimportantpleiotropiceffectsoronemajoreffectwhich

genewhichhaseitherimportantpleiotropiceffectsoronemajoreffectwhichcarriesthephenotypeoutsidethenormalrangeofvariation.However,themajorityofevidencepresentedinthisandpreviouschaptersisonthesideoftheconclusionthatthedifferencesbetweenthedogbreedsareproducedbylargenumbersofindependentgenes,eachhavingahighlyspecificeffectonbehavior,physiology,orstructure.

CONCLUSIONSANDHUMANAPPLICATIONS

Bothbreedandsexdifferencesaffectthepatternsofgrowthofyoungpuppies.Thereislittledifferenceinsizeatbirth,butasthepuppiesgrowoldertheybegintodivergeanddifferentiatefromeachother,theamountofdifferencebeingproportionaltoage.Canthisdifferentiationbetakenasamodelforthedifferentiationofbehavior?Growthisanaccretionaryprocess,withalittleweightbeingaddedeaclidaytowhatwastherebefore.Toacertainextent,thisisalsotrueofthelearningprocess,aseachdaythepuppyhasnewexperiencesandpresumablylearnsalittlemore.Inthisway,thetwotypesofdifferentiationaresimilar.

However,insolvingaparticularnewproblemthepuppydoesnotinvariablymakeuseofallthathehaslearnedpreviously.Infact,iftheproblemisnewenough,hemayhavetostartfromthebeginningandwillbeabletouseverylittleofhisoldknowledge.Furthermore,


theprocessoflearningoftenproceedsbysuddenjumpsorsaltationratherthangradualaccretion(Hebb,1949).Whileonecanweighadogandmeasureallthathehasgrown,itisdifficulttodeviseanytestsituationwhichwillmeasureallthathehaslearned,oreventogivehimmanydifferenttestsandaddtheresultstogetherinanymeaningfulway.Ourconclusionisthatwherelearningistrulyac-cretionary,themodelofgrowthwillapply,butthattherearemanycasesoflearningwhichdonothavethispropertyandforwhichgrowthishenceapoormodel.

Physicaltraitshaveobviouseffectsonbehavior.Theshort-leggeddachshundcannotrunasfastasanormal-leggedbeagle,andtheheavymusclesofaterrierhaveobviousadvantagesinfighting.Thiskindofeffecthardlyneedsscientificproof.Afurtherproblemiswhetherornotphysicaltraitshavemoresubtleeffectsonbehavior,andthisisrelatedtothegenetictheoryofpleiotropy.Proponentsofitsmostextremeformhavearguedthateverygenemusthave

Proponentsofitsmostextremeformhavearguedthateverygenemusthavesomeeffectoneverybodyprocess.Opposedtothiswehavethetheoryofspecificprimaryeffectsofgenes—thatagenehasoneprimaryeffectwhichmayormaynotaffectotherprocesses.Underthislattertheorysomegenesmighthavepleiotropiceffectsandothersnot.Wehavetestedthesehypothesesbymeasuringthecorrelationbetweenknowninheritedphysicaltraitsandbehavior.Ifthegeneraltheoryofpleiotropyweretrue,suchgenesoughttoaffectalmosteverybehavioraltest.Asamatteroffact,thegenescontrollinghairlengthandtheredcoloringofbasenjishadnoappreciableeffectonawidevarietyofbehavioraltests,orevenuponmeasurementsofbodyproportions.Theevidenceisdefinitelyinfavorofthetheoryofonespecificprimaryeffectofagene.Thisdoesnotexcludepleiotropyinspecialcases,andweknowofatleastonedoggenehavingpleiotropiceffects,thatformerlespotting.Eveninthiscase,however,thereisevidenceforaspecificprimaryeffect.

Relatedtothetheoryofpleiotropyisthetheoryofbodyandbehavioraltypes;i.e.,thatallthemanifoldeffectsproducedbyapleiotropicgenecanbesummedupasatype.Braceconductedaveryextensivetestofthetypetheorythroughthemethodoffactoranalysis.Whilethedogbreedshavebeenselectedastypes,thecrucialgenetictestintheF2populationshowsthatthebreedtypesdonotreappearassuchintheF2,s,eitherinbodyconformationorinotherphysicalcharacteristicssuchashairlengthandcolor.Theevidenceisinfavorofalargenumberofindividuallysegregatinggenesratherthanafewmajorgeneshavingpleiotropiceffectsand


producingseparatetypes.Thetypeconcepthasonlylimiteduseinmodernbiologyandisbeingreplacedbythestudyofvariationaccordingtopopulations.

Theseconclusionsandideashaveanimportantrelationshiptohumanaffairs.Freshfromusingthetypemethodtoclassifyanimals,manybiologistsinpastgenerationsthoughtofthehumanracesintermsoftypes.Aswehavepointedoutabove,thetypeconceptisausefulonewhereverasinglemajorcauseconsistentlyproducesseveraleffects.Theearlierclassificationofhumanraceswasbasedontheideaofonemajorcauseproducingskincolorandallotherassociatedcharacteristics,notonlyphysicalbutculturaltraitsaswell.Themodernstudyofracesaspopulationsshowsthateachgroupisenormouslyvariableinitself,andthatpopulationsunlikeinmanyrespectsmayhavethesameskincolor.Inthosegeneticallydeterminedcharacteristicswhichcanbe

sameskincolor.Inthosegeneticallydeterminedcharacteristicswhichcanbemeasured,suchasbloodgroups,humanpopulationsdifferintheaveragedistributionofcertaingenes,butthedifferencesbetweenaveragesareusuallysmallcomparedtothedifferencesbetweenindividualswithinthesamepopulation.

Whatdoesthismeanintermsofinterpretinghumanbehavior?Itdoesnotmeanthatphysicaldifferenceshavenoeffectonbehavior,butsimplythatthesedifferencesareofasimpleandunderstandablenature.AmericanNegroeshaveontheaveragelongerlegsinproportiontothetrunkthandoAmericanwhites(McKusick,1960).Onewouldexpectthatontheaveragetheymightbebetterperformersinjumpingandrunning,asindeedtheirperformanceinrecentOlympiceventswouldindicate.Inthecaseofskincolor,thereisnoevidencethatithasanyeffectotherthanwhatmightobviouslybeexpected,namely,thatNegroesendureseverephysicalexertionbetterinahotmoistclimatethandowhitepeople,presumablybecausetheyareabletoradiatebodyheatmorerapidly(Baker,1958).Alltheevidenceisagainstanyassociationbetweenskinorhaircolorandbehavioraltraitsotherthantheabove.Wherevercomparableintelligencetestscanbegivenunderconditionsofequalopportunity,therehavebeennodifferencesbetweendifferentraces(Anastasi,1958).Thekindsofbehavioraldifferenceswhichwenowfindbetweenpopulationsreflectthecombinedeffectsofculturalandenvironmentaladvantages.WeshouldrememberthatcivilizationsofatypeatleastcomparabletothoseofBabylonandEgyptwereinexistenceintheNewWorldwhenColumbusdiscoveredit.Atwo-thousand-yearstartgaveatremendousadvantagetotheolderculturewhenthetwocameintocompetition,butallindicationsarethatanotheradvancedcivilizationwouldhavebeendeveloped


onthiscontinentifithadbeenleftaloneunderfavorableenvironmentalconditions.Thereislikewiseeveryevidencethathumanbeingswholiveunderextremelyunfavorableenvironmentalconditionssuchasthefarnorthorthetropicsarebasicallyjustascapableasthosecomingfrommoretemperateregions,butthatthesevereenvironmentprovidesastronghandicaptothedevelopmentofthesecapacities.

Inshort,alltheweightofmodernscientificevidence,bothfromdirectstudiesonhumanbeingsandfromanimalstudiessuchasthisone,isonthesideoftheconclusionthatthehumanraceisdividedintopopulationsratherthantypes.Thesepopulationsarebecominglargerandlargerastheyabsorbformersmall

Thesepopulationsarebecominglargerandlargerastheyabsorbformersmalllocalpopulations,andasevenlargecontinentalpopulationsbegintomergewitheachother.

Indealingwithindividuals,whethertheyaredogsormen,weneedtorememberthateachisauniquecollection(orpopulation)ofgenetictraits,notatyperepresentingarace.Likewise,indealingwithagroup,weneedtorememberthatwearedealingwithapopulation:agroupofvariableindividualsratherthanasingletype.

THEEFFECTSOFHEREDITYUPONTHEBEHAVIOROFDOGS

Sofarinthisbookwehavebeenconsideringtheresultsofindividualtests,manyofthemespeciallyselectedforanalysisbecausegeneticsappearedtobeimportantanditsmodeofactionreadilyexplainable.Inthischapterweshallconsideralltheteststogetherandsoobtainanover-allandreasonablyunbiasedviewpoint.Thiswillgiveusinformationonthreeprincipalpoints:generalevidencefortheexistenceofMendeliansegregation,evidencefortheextenttowhichheredityaffectsbehavior,and,finally,evidencefortheexistenceofspecificandgeneralbehavioraltraits.

GENERALEVIDENCEOFSEGREGATIONANDDOMINANCE

Thedetailedanalysesofindividualtestshaverevealednumerouswaysinwhichcomplexinteractionsonthebehaviorallevelcanmodifytheexpressionofhereditaryvariation.Nevertheless,onthebasisofMendeliantheory,onewouldexpectgreatervariationinthehybridpopulationsinwhichsegregationwouldoccur,thanintheFiandparentalpopulations.Inordertogetanover-allpicture,wecombinedtheresultsfromthecockerspanielandbasenjibreedsandthetwoFihybridsinonepopulation,andcombinedthosefromthetwobackcrossesandthetwoFi>generationsinanother.Eachofthetwopopulationswasthuscomposedoffoursubpopulationshavingapproximatelyequalnumbers.Oneofthemincludedallthesegregatinghybrids,andtheotherallthenon-segregatingpopulations(Table14.1).

356

EFFECTSOFHEREDITY

TABLE14.1CompositionofCombinedPopulations

357

Threestatisticaloperationswereperformed.Inthefirst,thesub-populationsweresimplycombinedandthetotalvariancecalculated.Inthesecond,onlythevariancewithinpopulationswascombined;andinthethird,onlythevariancewithinlitterswascombined.Thelastshould,ofcourse,giveusthebestpictureoftheeffectsofsegregation,sincewithinalittertheeffectsofrandomvariationinenvironmentalfactorsaregreatlyreducedandtheeffectsofaccidentalselectionofdifferentsortsofparentsareeliminated.Within-populationvarianceshouldincludemoreenvironmentaleffects,aswellaseffectsofdifferencesbetweenstrainswithinapopulation,whilethetotalcombinedvarianceofallthesubpopulationsincludesvariationfromallsources,includingthatfromdifferencesbetweenthesubpopulationsthemselves.

IfidealMendelianpopulationshavingequalnumbersarecombinedintheaboveways,thereshouldtheoreticallybenodifferenceinthemeansbetweenthesegregatingandnon-segregatingpopulations,whetherornotdominanceispresent.Actually,therewerealargenumber(26outof44)ofsignificantdifferencesbetweenthetwo.Thisresultmayinpartbeduetothefactthatthecomponentpopulationswerenotactuallyequalinnumbers,anditalsomayberelatedtoaccidentalselectionofdifferentindividualsfortheparentanimals.

Withregardtovariation,thetheoreticalgeneticvarianceofthecombinedparentandFipopulationsshouldbegreaterthanthatofthecombinedsegregatingpopulations,47percentlargerinthecaseofnodominanceand18percentinthecaseofdominance.Theactualfigures(Table14.2)indicatethatthevarianceofthenon-segregatingpopulationswasgreaterinslightlyoverhalfofthevariables.Thissmallexcesswouldarguethatdominanceisacommonphenomenoninthesevariables.

Ontheotherhand,thetheoreticalwithin-populationgeneticvarianceofthenon-segregatingpopulationsshouldbezero,while


TABLE14.2

NumberofVariablesinWhichtheCombinedVarianceofSegregatingPopulationsExceedsthatofNon-segregatingPopulations

thatforthesegregatingpopulationsshould,onascaleof1.0,average.083inthe

thatforthesegregatingpopulationsshould,onascaleof1.0,average.083inthecaseofnodominanceand.146inthecaseofdominance.Eitherthevariancewithinpopulationsorthevariancewithinlittersshouldshowanimportantincreaseinthesegregatingpopulations.AglanceatTable14.2indicatesthatthisisindeedthecase.Asweprogressfromthecombinedtotalvariancetothewithin-littervariance,thereisanincreaseinthenumberofvariablesinwhichthesegregatingpopulationsaremorevariablethanthenon-segregatingones.Theratioof31to13issignificantlydifferentfromthatexpectedbychance(P=.005).Thisratioisapproximatelythesameinthevariableswhichshowsignificantdifferencesbetweenthebackcrossesandhenceshowimportantdifferencesbetweenthetwoparentbreeds.

Thustheover-allevidenceisconsistentwiththeassumptionthatMendeliansegregationincreasestheamountofvariationinhybrids,althoughthismaynotbetrueincertainindividualmeasurementssubjecttospecialbehavioralinteractions(seechap.12).Likewisethereissomeindirectevidencethatdominanceisprobablyacommonphenomenoninthisdata.

THEIMPORTANCEOFGENETICVARIATION:RESULTSOFANALYSISOFVARIANCE

Fromtheverystartwerealizedthatevenwithinpurebreedstherewasagreatdealofvariationbetweenindividuals,andouroriginalmatingplan,describedinchapter1,wasintendedtominimizeindividualgeneticdifferencesbyfirstdevelopingstrainsbasedontheoffspringofasinglematingand,second,bycrossbreedingbetweenindividualscomingfromasinglematingineachoftwopurebreedingstocksthusdeveloped.Thisplanshouldhavehadtheeffectofreducingvariationduetoindividualdifferencesrelativetovariationbetweenbreeds.Thisfactshouldbekeptinmindininterpretingtheresults.

EFFECTSOFHEREDITY359

WiththehelpofDr.GuntherSchlagerandtheJacksonLaboratoryBiometricService,wemadeanextensiveanalysisofvarianceofthe50variablesusedinBrace's(1961)factoranalysis.Foreachofthesevariables,thevariancewascomputed:(1)betweenbreedsorhybridpopulations,(2)betweenlitterswithinpopulations,and(3)withinlitters.Thefirstofthesecomponentscanbeassumedtobelargelygenetic,aseveryeffortwasmadetorearallbreedsunderuniformconditions.Likewise,thethirdcomponentofwithin-littervarianceshouldreflectalargeamountofgeneticvariation,thatbetweenindividuals.Sinceallmembers

alargeamountofgeneticvariation,thatbetweenindividuals.Sinceallmembersofalitterunderwenttestingatthesametimeandhadverysimilarenvironments,itcanbeassumedthatthispartofthevariancehasalargegeneticcomponent.Ontheotherhand,thebetween-littervarianceshouldincludealargepartoftheenvironmentaleffects,especiallywhererepeatedlittersfromthesamematingweretested.Wheredifferentmatingsareinvolved,italsoreflectsgeneticdifferencesbetweentheparents.

Thesecomputationsweremadeforallpurebreeds,thetwoparentbreeds(cockersandbasenjis),thetwoFi's,thetwobackcrosses,andthetwoF2's(Table14.3).Sixofthevariablesweredistributedinadichotomousfashionsothatvarianceestimatescouldnotbemade.Inthesecases,thechi-squareanalysiswasusedtomeasuretheimportanceofdifferencesbetweenpopulations.

Afurtherandmoredetailedanalysiswasdoneforselectedback-crossandF2populations.Intheseselectedgroupsthereweretwolittersfromeachoftwomatingsineachpopulation.Theparentsineachcasewerebrothersandsistersfromthereciprocalcrosses,sothatthewholegroupwasdescendedfromfoursiblingbasenjisandfoursiblingcockerspaniels.Inthesepopulations,thebetween-littervariancecouldbeseparatedintoabetween-matingcomponent(largelygenetic)andabetween-litter-within-matingcomponent(largelyenvironmental).

Sincelittersizeswerevariable,variancecomponentswerecomputedaccordingtothemethodofGower(1962).Inthismethod,thewithin-littervariancevalueisassumedtobecorrect,buttheremainingtwocomponentsarecalculatedwithsomedegreeofapproximation.Themethodtendsthereforetoslightlyreducetheestimatesofbetween-breedandbetween-littervariance;thatis,theseareconservativeestimates.

Thegeneralresultistogiveusestimatesoftherelativeimportanceoftwolargelygeneticcomponents,between-breedandbetween-mating,wherethelatterissomewhatminimized.Italsogivesusa


TABLE14.3ProfortionofVarianceAttributabletoPopulationDifferences

Variable

All

Pure•BreedsBA&CS

Fi's

Back-

F:'s

SelectedBack-SelectedcrossesFi's

PhysicalMeasurement:

Weight27**

Bodvlength59**

Shoulderheight52**

Chestcircumference.Waistcircumference.

Brisketdepth

Chestbreadth27**

Femurdiameter0*

Humerusdiameter21**

Thighcircumference16**

Mean

Physiological-Emotional(HeartRates):Averagerate,11-16weeks

Adultrate

Change,quieting

Change,bellringing

Arrhythmiaindex

Mean.

Emotional:

Distressvocalizationwhileweighed,1-4weeks

Activityinconfinement

Responsestostimulationduringreactivitychange,aloneandwithexperimenter

Activityduringbellringing....

Posture

Musculartremor

Vocalization*1

Investigativebehavior

Escapeattempts

Mean.

Socialrelationships:Withhumans:

Avoidanceandvocalization,

5weeks

Playfullighting,13-15weeks..Approachandfollowing,13-15

weeks

Withdogs:

Dominancescored

Mean

Trainability:

reedtraining:

Inactivitywhileweighed,5-weeks'1

16

27

39*46*27*10*66*

5^

26*

13*

134*14*44*

24*

28*

25

29**

15**

18**

21

42**76**82**37**21**65**27**4*58**19**

43

27*37*42*11*0

23

24*

8*11*43*

0

46*56*

25

59<

45

18*11*62*

2*48**11

0

315*

0

17

016*

29*

50

22*

11*

7

11

5*33**53**21**11**33**

0

0

021**

18

24**17**16**18**0

15

0

0

0

40*

13*29*

in

24**10

30**

:i

oo

30*


EFFECTSOFHEREDITY

361

d—dichotomousdistribution,variancecomponentsnotcalculated.

pictureofthechangeindistributionofthebetween-breedcomponentasaresultofhybridization.

ofhybridization.

Resultswithfivepurebreeds.—AsTable14.3shows,thereisonlyonevariableoutofthe50whichdoesnotshowsignificantdifferencesbetweenthebreeds,atleastonthe5percentlevel.Thegreatmajorityofthedifferencesaresignificanttofarbeyondaprobabilityof.01.Sincethesevariableswereselectedtorepresentallimportantbehavioraltests,itisobviousthatbreeddifferencesinbehaviorarebothrealandimportantinmagnitude.

Withrespecttotherelativeamountsofbreeddifferences,thesevaryfromzeroto66percentofthetotalvariance.Thelargestbe-


tween-breedcomponentoccursinthearrhythmiaindex,producedalmostentirelybythefoxterrierbreed,whichishighlydifferentfromalltheothers.Anearzeropercentageisfoundinthevariableofchangeinovertactivityduringthereactivitytest,butonlyinthepartinwhichthedogisleftaloneandlatercomforted.Thecomputationsalsoreduceasmallbutsignificantdifferenceinoneofthephysicalvariables(femurdiameter)tozero.

Asshownattheendofthesametable,theportionofvarianceattributabletobreeddifferences(comparabletotheintraclasscorrelationfiguresinpreviouschapters)averagesapproximately27percentforbothphysicalandbehavioralvariables.Evenifthephysiologicalmeasuresareomitted,theremainingbehavioralvariablesstillaverage25percent.Wecanconcludethatbehavioraldifferencesbetweenthefivepurebreedsareasimportantasdifferencesinphysique,eventhoughphysicalmeasurementsareusuallyconsideredtobemoreaccuratethanbehavioralones.

Resultswithbasenjisandcockerspaniels.—Asmightbeexpected,therearefewersignificantdifferencesbetweenthesetwoparentbreeds(Column2,Table14.3)thanwhenallfivebreedsareconsidered.Onenotableexampleisthatofthearrhythmiaindex,inwhichthereisnodifferencebetweencockersandbasenjisoranyoftheirhybrids.Nevertheless,therearestill35outof50variableswhicharesignificantlydifferentatthe.01levelorless.Thesetwobreedsareobviouslydifferentfromeachotherinmanyrespects.

Indeed,certainofthebetween-breedvariancesevenexceedthosecalculatedforallfivebreeds.Thoseforleashfightingandrunningtimeonthelongbarrierofthedetourtestare77and78percentrespectively.Almostallthephysical

thedetourtestare77and78percentrespectively.Almostallthephysicalvariablesarehigher,thatforheightbeing82percent.Nevertheless,thereisagreatdealofindividualoverlapbetweenthetwoparentstocksinmostofthevariables,eventhosewhichshowthegreatestdifferences.Thisoverlapmightbecausedeitherbyenvironmentalvariationorbygeneticvariationwithinthebreed,aquestionansweredbyfurthercomputationsdescribedlaterinthischapter.

ResultswiththeF\sandF/s.—Differencesbetweenthereciprocalcrossesinthesetwopopulationscouldbecausedbyaccidentalselectionofdifferentparents,Inmaternalinheritance,orbysex-linkedinheritance.Asshowninanearlierchapter,thereisnoevidencethatsex-linkedinheritanceaffectsanyofthevariables,and,indeed,thisisnotsurprising.Thereare39pairsofchromosomesinthedog,andthereforethechanceoffindingagenecarriedbytheXchromosome


isquitesmall.Maternalinheritanceisalikelypossibilityonlyinthecaseofapproachingandfollowingbehaviorexhibitedtowardahumanhandler,whereboththeFi'sandFu'sshowlargedifferencesandwherethereisalogicalmeansofpassingonatraitfromgenerationtogenerationbyfollowingthematernalexample.

TherearemanymoredifferencesbetweenthereciprocalFicrossesthanwouldbeexpectedpurelybychance.Outof50variables,2.5wouldbeexpectedbychanceatthe.05level.Actually,20variablesshoweddifferencessignificantatthe.05levelorless.Sincetwoofthethreealternativeexplanationslistedabovehavebeeneliminated,thereremainsthepossibilitythatthedifferencesbetweentheF/swerecausedbyaccidentalselectionoftheparents.ThisisespeciallylikelywherethedifferencesbetweentheFi'sareoppositefromthoseintheparents,asinallsixofthephysicalmeasuresandthreeofthebehavioralmeasures.Theresultsthereforeindicatethatindividualgeneticvariationwithinabreedisimportant.

However,thenumberofdifferencesbetweenthereciprocalcrossesisgreatlyreducedintheF2generation,therebeingonlysixdifferencessignificantat.05orless.SomeofthisreductionisundoubtedlyproducedbyselectionofasmallnumberofFiparentsfromtheoffspringoftheparentsselectedinthepreviousgeneration,whichwouldhavetheeffectofdecreasingvariation.Itisalsopossiblethatsomebreedcharacteristicsarefullydevelopedonlyinthematernal

possiblethatsomebreedcharacteristicsarefullydevelopedonlyinthematernalenvironmentofthepurebreeds;thatis,thedevelopmentofbreedcharacteristicsmayinpartdependuponanenvironmentproducedbyassociationwithmembersofthesamebreed.Forexample,foxterriermothersappeartobeconsiderablymoreaggressiveduringweaningthandoothermothers,andthismayaidinthedevelopmentofexcessiveaggressivenessamongtheirpups.Thisgeneralpossibilityisreinforcedbythefactthat11outofthe14significantdifferencesinbehaviorareinthesamedirectionasdifferencesbetweenthepurebredparents.

Resultsfromthebackcrosses.—Inthesepopulations,geneticsegregationtakesplace.Theresultisthatgeneticvariationisredistributed,beingdecreasedbetweenpopulationsandincreasedwithinpopulations.Onanytheoryofinheritanceinvolvingonesetofalleles,thereshouldbedifferencesbetweenreciprocalbackcrosses.Selectingthosevariableswhichshowhighlysignificantdifferencesshouldthereforegiveagroupofvariablesinwhichthebetween-breedcomponentisgreatest.Thenumberofvariablessignificantat.01isreducedfrom35intheparentstrainsto27inthebackcrosses,andfor


themostpartthevariablesshowingmostsignificantdifferencescorrespondtothosewhichshowedthemaximumdifferencesbetweentheparents.

Therearethreeexceptions.Oneoftheseistheaverageerrorscoreinthemazetest.InthisvariablethereisalargedifferencebetweenthetwoFi's,butnodifferencebetweenthetwopurebreeds.Thesignificantdifferencebetweenthebackcrossesprobablyresultsfromaccidentalselectionofparentswhicharedifferentfromthebreedaverages.Thesecondexception,tremorduringthereactivitytest,hasthesameexplanation.Finally,thereistheerrorscoreintheT-maze,forwhichthereisnoobviousexplanationexceptthattheoriginalsimilaritybetweentheparentstrainsmayhavebeenproducedbydifferentgeneswhichsegregatedseparatelyandthusproduceddifferencesbetweenthebackcrossgenerations.

ResultsfromselectedbackcrossesandF2S.—Intheabovecalculationsitisimpossibletodifferentiatebetweenthebetween-matingvarianceandthebetween-littervariancewithinmatings,asvariousaccidentspreventedourobtainingrepeatedlittersfromeverymating.Thefollowingcalculationsarebaseduponaselectedgroupofmatingsinwhichitwaspossibletoobtaintwolittersfromeach.Theoriginalparentswereallobtainedfrombasenjimating4andcockerspanielmating7,sothatdifferencesbetweenthematingsrepresent

andcockerspanielmating7,sothatdifferencesbetweenthematingsrepresentgeneticdifferencesbetweensiblings.

DescendantsfromthesefourmatingsproducedtwolitterseachinthebackcrossandF2generations,sothatforeachpopulationtherewerefourlittersand19to21animals.Itisthereforepossibletomeasurethevarianceproducedbydifferencesbetweenmatingsinadirectmanner.ItshouldberecalledthatinthebackcrossandF2generations,thevarianceduetosegregationismaximized,producingalargeamountofwithin-littervariance.Thedifferencesbetweenmatings,however,shouldnotbeaffectedbysegregationbutonlybyaccidentalselectionandsmallnumbers.

AsseeninTable14.3,thenumberofsignificantdifferencesbetweentheselectedpopulationsisstillfurtherreducedbecauseofthereductioninnumbersandtherestrictionofdifferencesbetweenmatings.Thevariableswhichstillshowsignificantdifferencesarethesameasthevariableswhichshowedthelargestdifferencesbetweenthebackcrosses,withthreeexceptions:theconfinementtest,thetrailingtest,andthespatial-orientation-persistencetest.Thesethreeshowsignificantdifferencesbetweenthepurebreedsbutnotbetweenthetotalbackcrosses.Thefactdiattheselectedbackcrossesaresignificantlydifferentprobablyresultsfromanaccidentalselec-

EFFECTSOFHEREDITY

365

tionofparentswhichshowedgreaterdifferencesthantheaverage.Thereshouldbeaslightlyhigherproportionofwithin-littervarianceintheF2'sthaninthebackcrosses,becauseofreductioninthelatterofageneticvariationduetodominance,andthisinfactistheresult.AsseeninTable14.4,thewithin-littervarianceineachF2populationisgreaterthaninthecorrespondingbackcrosspopulation.

TABLE14.4VarianceComponentsofEachSelectedBackcrossandF2Population

Population

BetweenMatings:BetweenLitters

WithinLitters

WithinLitters

MeanVarianceComponentsof10PhysicalMeasures,inPercentages

MeanVarianceComponentsof34BehavioralMeasures,inPercentages

Thebetween-matingvarianceaveragesapproximately12percentonbothphysicalandbehavioralvariables.Thebetween-litter-within-matingvarianceisveryclosetothesameamount.Itshouldberecalledthattheformerrepresentsgeneticdifferencesbetweenbrothersandsistersratherthanarandomsampleofthebreedandisthereforeaminimumestimate.Itmustbeconcludedthatgeneticdifferenceswithinbreedsareimportant.Ifwecomparetheseresultswiththosefromthepurebreeds,about75percentofthevarianceoccurswithinbreeds,includingabout21percentduetodifferencesbetweenlitters.Ifweassumethatone-halfofthelastfigure,or10.5percent,iscausedbydifferencesbetweenmatings,thefiguresarequitecomparable.

InTable14.5thevariancecomponentsofcertainselectedvariablesshowingthegreatestdifferencesbetweenthebackcrossesareshown.Ontheaverage,thereisnodifferenceintherelativesizeofthevariancecomponentsbetweentheseandthetotalofallvariables.Thereare,however,greatindividualvariationsbetweenthetests.Forexample,heightshowsalmostnobetween-matingvariance,


TABLE14.5

MeanVarianceCoîponentsemVariablesShowingDifferencesbetweenthebackcrosseswithap<.01

Variable

Bet'.veenMatings

BetweenWithin

Litters

Height

Ave.heartrate,11-16weeks

Adultheartrate

Heartratechange,quieting

Heartratechange,bellringing

Activityinconnneraent

Musculartremor

Approachandfollowing,13-15weeks.

Leashlighting

Finalrunningtime,longbarrier

Vocalization,U-shapedbarrier

Trailing

T-maze,motivation

T-maze,errors

Meantotal.

11

12

whereasinfantileheartrateshowsagreatdeal.Thiswouldmeanthatintheselectedsample,parentswereaccidentallychosenthatwereuniforminheightbutvariableinheartrate,althoughitwillberecalledthatinthetotalsampletherewasagreatdealofparentalvariationinheight.

Inthecaseofapproachandfollowing,thereisnobetween-littervariancewithinmatings.This,itwillberecalled,isavariableinwhichmaternalinheritanceisalikelvpossibilitv.IntheT-mazeerrorscore,whichisoneinwhichtheparentpurebreedsshowednodifferences,thereisalargebetween-matingvariance.Inthiscasetherewasprobablyaccidentalselectionofdifferentsortsofparentanimalsfromthetwobreeds,althoughthebreedsthemselvesaresimilarontheaverage.Finally,intheleash-fightingtestalargebetween-matingcomponent

average.Finally,intheleash-fightingtestalargebetween-matingcomponentconfirmsconclusionsfromthedetailedanalysisofthistestinchapter12.

Conclusions.—Reviewingthiscomplexmaterial,wecancometocertainfirmconclusions.Oneisthatthedifferencesbetweenbreedsareimportant,bothinphysicalmeasurementsandbehavioralmeasurements.Thevarianceaveragesbetween25and30percentofthetotalandrangesashighas66percent.Inonlvonebehavioraltestandonephysicaltestarebreeddifferencesestimatedasbeingclosetozero.

Atthesametimethereisagreatdealofoverlapbetweenthebreeds.Althoughthisoverlapisinpartcausedbyrandomenvironmentalfactors,itliasasubstantialgeneticcomponent.Thegeneral


picturewhichemergesfromthestudvisthatinmosttraitsthereareaveragebreeddifferences.Takinganytwobreedsatrandom,onewouldexpectalargenumberofsignificantdifferencesbetweenmeanscores.However,therearegenetieallvoverlappingindividualsineachoftiiesebreeds,sothatinmanytraitsonebreedcouldbemadeliketheotherwithinaveryshorttimebyselection.Thismeansthatthedogbreedshaveretainedagreatdealofgeneticflexibility.

Forexample,fightingtheleashischaracteristicofbasenjisandisshownbvnocockerspaniels.Nevertheless,thereareafewbasenjiswhichlackthistrait,anditwouldbepossiblebvselectiontoproduceastrainverymuchlikecockersinthisrespect.Thistypeofgeneticoverlapisnotnecessarilvreciprocal,asitwouldprobablybemuchmoredifficulttoselectcockersintheoppositedirection.

Inafewcasesselectionhasapparentlyproducedtraitsforwhichcertainbreedsarevervnearlygenetieallvhomozvgous,suchasthelowcapacityfordevelopingfightingbehaviorinthehoundbreedsandthehighcapacitvforthesametraitintheterrierbreeds.Suchinstancesare,however,relativelyrare.

Withinabreed,individualcapacitiesarelikelytobehighlyvariable;butmostindividualsmaybeabletoperformthetasksrequiredofthembvbringingdifferentcapacitiesintoplay.Outstandingperformerswithinabreedprobablyhavespecialcombinationsofcertaincapacitieswhicharelargelytheresultofaccidentalselection.

EVIDENCEFORTHEEXISTENCEOFGENERALTRAITS:RESULTSOFFACTORANALYSIS

Alternatetheoriesofinheritance.—Wehavenowconfirmedtherealityofalargenumberofdifferencesbetweenthebehaviorofbasenjisandcockerspaniels.Thebasenjishadatendencytofighttheleash,toshowagreatdealofplayfulaggressiveness,andtobehighlyfearfulasyoungpups.Incontrast,thecockersalmostneverfoughttheleash,hadlesstendencytoplayfullyfightandchewontheirhandlers,andshowedverylittlefearasyoungpuppies.Wemightsupposeeitherthatallofthesedifferencesarecausedbvonebasicbehaviortrait,orthateachoftheseisaspecialtraitandunrelatedtotherest.Ifthefirsttheoryistrue,thenthetestresultsshouldbecorrelatedeveninthesegregatinghybridgenerations.Ifthesecondtheoryiscorrect,thetestresultsshouldshowlittleifanycorrelation.

Thetraitsare,ofcourse,correlatedintheoriginalpurebreeds,nomatterwhatthegeneticsituationmightbe,andafewindependenttraitsmightbecorrelatedeveninthesegregatinggenerationsif


theywerecausedbytwogeneswhichareclosetogetheronthesamechromosomeandhencecloselylinked.However,sincethedoghas39differentpairsofchromosomes,thechancesofcloselinkagearenotverygreat.

Thetheoreticalresultisalsocomplicatedbythefactthataparticularbehaviortraitmightbecausedeitherbyasinglemajorgeneorbyseveralgeneswithminoreffects.Thefirstconditionwouldproduceverystrongcorrelationsbetweentests.Thesecondcouldproducesuchcorrelations,butonlyiftheeffectsofminorfactorswereadditive.Ifaparticulartraitisproducedonlybyaspecialcombinationofgenes,itwilldisappearduringsegregationandbefoundonlyinaverysmallnumberofindividuals,notenoughtoproduceanystrongcorrelation.Forexample,ifatraitwasproducedbyacombinationofthreerecessivegenes,thiscombinationwouldappearintheF2generationinonlyoneoutof64individuals.Inanycase,onewaytotestthesevarioustheoriesisthroughanalysisofcorrelations.

Thetheoryoffactoranalysis.—Dr.JosephRoyce,whowasatthetimewebegantheseexperimentsagraduatestudentworkingwiththelateProfessorThurstone,stronglyadvocatedtheuseoffactoranalysisonourdataandhas

Thurstone,stronglyadvocatedtheuseoffactoranalysisonourdataandhaspresentedthetheoryinvolvedinseveralpapers(1950,1957,1963).Ifthehypothesisofbasicgeneraltraitsiscorrect,factoranalysisshouldgiveaclear-cutindicationofthenatureofthesetraitsandofthesituationsinwhichtheyappear.Themethoddoeshaveonelimitation.Sinceitisbasedoncorrelations,itwillworkonlywherethebasicmathematicalassumptionsofcorrelationaremet.Theseassumptionsarethatcausalfactorsproducecertainspecificeffects,andthattheseeffectsareadditiveanddistributedinnormalcurves.

Thefactorialmethodhasprovedveryusefulinanalyzingtheresultsofhumanintelligencetests.Eachtestscoreistheresultofaddingtogetherseveraltestitems.Itthereforefulfillsthecriterionofadditiveeffects.Sincemanyintelligencetestsweredesignedbydevisinganumberofquestionsandproblems,andafterwardselectingthosetowhichstudentsgavedifferentanswers,theoriginalintelligencetestswereamixtureofmanydifferentsortsofquestions.Thefactorialmethodwassuccessfullyusedtosortoutthecommonfactorsinvariousquestionsandtoproducetestswhichcouldbeinterpretedintermsofspecialcapacities.ThurstoneandStrandskov(Strandskov,1953)testedthehypothesisthatthesepurifiedtestsrepresentedbasicgeneticdifferencesincapacitiesbygivingtheteststoidenticaltwinsanddeterminingthecorrespondencebetween


them.Inmostcasesthecorrelationswerelow,indicatingthathereditywasnothighlyimportantindeterminingthesecapacities,althoughsomeofthemorestrictlyphysiologicaltestsshowedhigherresemblances.Judgingfromtheevidenceontransferoftraining,whichindicatesthatpeopleareabletotransfermateriallearnedononesituationonlytocloselyrelatedsituations,itisprobablethatthefactorsobtainedbyThurstonerepresentproblemswithacommonrecognizablesimilarityratherthanproblemssolvablebyasinglecommoncapacity.Aswehaveseenfromtheresultsofperformancetestswithdogs,manycapacitiesmaybeinvolvedinthesimplestperformancetest,andanimalscanorganizethesecapacitiesinvariousways.

Afactoranalysisofemotionalandphysiologicaltests.—Rovce(1955)didafactoranalvsisoftestsmadeon53purebreddogsdistributedinsixdifferentbreeds.Thirty-twovariableswereincludedintheanalysis.Thesevariableswereobtainedfromonlyfivedifferenttestsituations,andsomeofthemwouldbeexpectedtobecorrelatedsimplybecausetheyoccurredinthesametest.Thebasiccorrelationtable,however,showsmanymorecorrelationsthanmightbe

basiccorrelationtable,however,showsmanymorecorrelationsthanmightbeexpectedfromthissourcealone.Ofthe396correlationsofunrelatedtests,85weresignificantatthe.05level,asopposedtothe19.8whichmightbeexpectedbychance.Realcorrelationsbetweenthedifferenttestsmustexist,althoughthesemaybecausedbythefactthattheanimalstestedbelongedtopurebreedsandhencehadcommontraitsproducedmerelybybreedselection.Rovcewasabletoidentifyseveralfactors,twoofwhichwerehighlyphysiological.Onewascharacterizedbyhighbloodpressureandarrhythmicheartbeatandmayhavebeenassociatedwithemotionalreactionsoftimidity.Thesecondshowedahighdegreeofchangeinheartratetosocialstimulation,associatedwithahighdegreeofexternalactivity.Fourfactorswerelargelybehavioral.Inoneofthese,therewerehighloadingsforbothplayfulaggressivenesstowardhumanhandlersandconfidencewhilebeingweighed.Asecondwascharacterizedbyahighdegreeoftimidityinreactiontopeople,alongwithsomeemotionalreactions.Athirdtestincludedahighdegreeofreactiontothenoiseofabellringing,andafourthwascalledgeneral-activitylevel.

Oneofthemostinterestingresultswastheindicationthattimidityandaggressivenesswerenotoppositeendsofthesamecontinuumbutwerefoundindifferentfactors.Theresultsalsoindicatethatthereareseveraldifferentkindsoftimidityandthusargueforthetheoryofhighlyspecificeffectsofgenes,butsinceanyofthefac-

torsmighthavebeencausedbyaccidentalbreedassociation,thislastconclusionisnotafinalone.

Rovce'sfactoranalvsisenabledustoselectcertainvariableswhichseemedtohaveimportantgeneraleffectsandtoeliminateotherswhichseemedtobeeitherinconsistentorspecific.Thusthetestingprogram,andparticularlythescoringofcertaintests,wascon-siderablvimproved.Anotherresultwasthedemonstrationthatthesametestscoresgivenatdifferentagescameoutindifferentfactors.Thetimiditv-confidenceratingonthefifthweek,orfirsttesting,appearedtobelargelvindependentoftheaverageratingsobtainedfrom5to10and11through16weeks.Thelasttwo,however,wereconsistentlvassociated.

Factoranalysisofperformancetests.—AnastasiandSchmidt1955),didasimilarpreliminaryanalvsisofperformancetests.Thedogstestedincludedallfivepurebreeds,totalingsome50animals,plus23oftheFihybridsbetweenthecockersandbasenjis.ThegrouptestedwasthereforesomewhatsimilartothatusedbvRoyce.Theresultsofeightdifferenttestsituationswereincluded,butseveraloftheseincludedmorethanonescore,makingatotalof17variablesto

severaloftheseincludedmorethanonescore,makingatotalof17variablestobeanalyzed.ThemethodwasthesameasthatusedbyRovce,thecentroidmethod.

Theanalysisproducedfivefactors.Oneofthesewasclearlva"test"factor,involvingtwoscoresfromonetest,andmeantlittleelsethanthatthesetwoscoresweresimilartoeachother.AnotherfactorchieflvincludedthreescoresindicatingpoorperformanceontheT-mazetest,plusscoresassociatedwithgoodperformanceonthesecondbarrier(maze)test.SincetheprincipalcauseoferrorintheT-mazeisatendencvtoalwaysruntothesamesideandthusshowpositionpreference,thisfactorwascalled"persistenceofpositionalhabits."Itisinterestingthatalaterdetailedanalysisofthesecondbarriertestrevealedbreeddifferencesinthetendencytoformsuchhabits,thebeaglesbeingquitedifferentfromtherestofthebreedsinbeingslowtoformfixedhabits.

Theotherfactorswereinterpretedaslargelvemotionalratherthanintellectualinnature.Factor1wascalled"impulsiveness*;Factor2,"docility":andFactor4,"visualobservation."

Someofthedifferentscoresonthesametestsituationappeared

indifferentfactors,particularlythoseonthebarriertest,butinmost

fromonetestappearedinthesamefactor.Onthis

swecouldselectthemostimportantscorefromeachtestfor

detailedanalysisandfuturework.

Whetherthesefactorsweretheresultofthecorrelationsarising


fromselectionofbreedtvpes,orwhetherthevrepresentedgeneralbehaviortraitsindogs,wasnotapparentfromtheresults.

Consideringthetwopreliminaryanalysestogether,itlookedasthoughitmightbepossibletoaccountformostofthedifferencesindogbehavioronthebasisofafewemotionalandtemperamentaltraitshavinganeffectonperformanceaswellasonemotionalexpression.Thetestofthistheorywastocombinebothemotionalandperformancetestsinasinglefactoranalysisandtofurther

emotionalandperformancetestsinasinglefactoranalysisandtofurtherdeterminewhetherornotthesecharacteristicswerereallybasictraitsbyapplyingfactoranalysistothesegregatinghybridsaswellastothepurebreedsandFihybrids|Brace,1961.

Ageneralfactoranalysis.—Brace'sextensivefactoranalyseshavealreadvbeendescribedinchapter13inconnectionwiththeeffectofphysiqueonbehavior.Braceusedthe40behavioraland10physicalvariableslistedinTable14.3asabasisforseparatefactorialanalysesoneachofthepurebreedsandeachhybridpopulation,aswellasonseveralcombinedgroups.Ofthese,resultsfromtheF?'sweremostimportant,sincethevwerebasedonthelargestnumbersandonthepopulationwheremaximumeffectsofsegregationmightbeexpected.

ItwillalsoberecalledthatallthephysicalmeasurementscameoutasasinglefactorofgeneralsizeintheF2generation,indicatingthattherewasnogeneticbasisforphysicaltypes.Inbothcockerspanielsandbasenjis,however,thephysicalmeasurementsdidappearintwofactors,indicatingthattherewerelong-andshort-bodiedtypesofanimalswithinthepurebreeds,probablvrelatingtostrainswithinabreed.Inthiscasetheremayhavebeenvariationinonerespectonly,namely,bodylength,producingtwotvpesofdogs.Thusthemethodiscapableofidentifyingtypesifthevdoexist.

Wecanagainaskthemostimportantquestion:isthereanyindicationoftheexistenceoftruebehavioraltypes?Anaffirmativeanswerwouldberelatedtothegeneraltheoryofpleiotropvdiscussedinthelastchapter:namely,theexistenceofmajorgenes,eachofwhichproduceseffectsinmanvdifferentsituations.TheF2populationgivesthemostclear-cuttestofanyhybridgroup,sincetheeffectofallgeneticfactorsshouldappear,andsincethereshouldbeaminimumeffectofgeneticlinkageuponcorrelation.

Inthefirstanalysis,wecanexamineacompletelynullhypothesis:thatnoneofthebehavioralvariablesarerelatedtoeachotherasidefromthosewhichareobviouslycorrelatedbecausethevwerederivedfromthesametestsituation.Thishypothesiscanbediscarded,becausethecorrelationsbetweenvariablesindifferentbehavioral


TABLE14.6

Factor2,Activity-SuccessintheCombinedF2Generation(Brace)

Factor2,Activity-SuccessintheCombinedF2Generation(Brace)

testsfarexceedthenumberexpectedbychance.Thedifferenttestsaredefinitelyrelatedtoeachotherinsomeway.However,thecorrelationsbetweenthemintheF2generationareuniformlylow.IfthereweremajorgenesforbasictraitssegregatingintheF2>s,wewouldexpectgroupsoftestswithhighcorrelationsbetweenthem.Lookingatthefactorsthemselves,weseethatFactor2intheF2generationincludesalargenumberofperformancetestsandcertainmeasuresofhighactivity(Table14.6).Bracethereforelabeledit"activity-success."Factor3includesallofthemeasuresofheartrateandafewwhichmayindicatetimidity(Table14.7).Beyondthis,Factors4and5includeonlymiscellaneousvariableswithlow

TABLE14.7

Factor3,Heart-Rate,intheCombinedF2Generation(Brace)

Variable

Highadultheartrate

Lowarrhythmiarate

Manyerrors,U-shapedharrier

Littleplayfulfighting

Muchdistressvocalizationwhileweighed

Activeduringbellringing

Greatdocility,sittraining

SlowonT-maze

Muchtremor,reactivity


Erectposture,reactivity

Highinfantileheartrate

Muchvocalization,U-shapedbarrier....

Loading

.68.56.43.43.41.37.34.33.32.32.31.31.30

EFFECTSOFHEREDITY

373

loadings.TherearethereforeonlytwoexplainablebehavioralfactorsintheF2hybrids.

Theothergroupsofsegregatinghybridsshowsimilarresults.InthebackcrosstothebasenjitherearetwofactorsverysimilartothoseintheF2,andpossiblyathirdwhichconsistsofagroupoftestsindicatingahighrateofvocalization.Inthebackcrosstothecockers,Factor2isagainmarkedbysuccessonavarietyofperformancetests,althoughtheseareadifferentgroupfromthoseemphasizedintheothertwohybrids.Likewise,thenextfactorisonewhichcanbelabeled"heartrate,"althoughnotasdefinitelyasintheothertwo.

Anotheranalysisinwhichgeneticdifferenceswouldbeexpectedtobehighlyimportantisthatofthecombinedpurebreeds,inwhichbreeddifferencesaremaximized.HereFactor2isagainoneofgoodperformanceonthesameseriesoftestsasintheF2andtheback-crosstothebasenji.Factor3isoncemorearecognizableheartratefactor.Thusthereappeartobeonlytworecognizablebehavioralfactorsderivedfromthepopulationsinwhichgeneticdifferencesshouldbeimportant.

ComparingthisresultwiththatintheFigeneration,inwhichgeneticdifferencesaretheoreticallylessimportant,wefindanentirelydifferentsituation.Herethereisonlyonerecognizablebehavioralfactor,whichincludesallofthe11measuresfromthereactivitytests,eachloadingindicatinganactiveanimalinovertbehaviororinheartrate(Table14.8).Thus,inapopulationinwhichgenetic

TABLE14.8Factor2,Reactivity,intheCombinedFxHybrids(Brace)

ReactivityTests

OtherTests

Loading

Activeinvestigation

Highadultheartrate

Erectposture

Littlechangeinheartrate.Activeduringbellringing.

Muchvocalization

Activeescape

Littlechangeinactivity..Littlecardiacarrhythmia.

Littlevocalization,leashtrainingLittlefearofhumanhandlersMuchinterference,leashtraining

Muchdistressvocalizationwhileweighed

Littlechangeinheartrate,bellringingLittletremor

ActivewhileweighedMuchplayfulfighting

FastonT-maze


.71.63.61.59.57.51.50.49.46.45.42.40.40.39.38.38.33.31.30


differencesarelessimportant,thegreatestamountofcorrelationappearstocomefromacommontestsituation.

Bracecametotheconclusionthathewasdealingwithfourmajorfactorsinallthedogs:bodysize,activity-success,heartrate,andgeneralactivity.Insteadofavarietyofgeneraltraits,theevidenceshowsthatthereareonlyalimitednumber.

Wemaynowtakeasecondlookatthemostimportantbehavioralfactor,activity-success(Table14.6).Itincludesaverylargenumberofsignificant

activity-success(Table14.6).Itincludesaverylargenumberofsignificantfactorloadings,noneveryhigh,butmostofthemindicatinggoodperformanceonavarietyofperformancetests.Infact,almostalloftheintelligencetestsareincluded.Alongwiththistherearehighloadingsoncertainreactivitytests,indicatinghighactivityandgeneralconfidence.Wecanthereforelabelthisfactor"Generalgoodperformanceandactive,confidentbehavior."

Asimilarfactorinvolvinggoodperformanceappearsintheback-crosstothebasenjis.Factorsinvolvingseveralperformancetestsarealsofoundinotherhybridpopulationsandinthepurebreeds,butthereislessconsistencyabouttheircomposition.LookingatthecorrelationtablesoftheF2'sandbasenjibackcross,weimmediatelynoticealargenumberofsignificantcorrelationswiththetrailingtest(Table14.9).

TABLE14.9

CorrelationsofPoorPerformanceontheTrailingTestwithPerformanceinOtherTestsinTwoHybridPopulations

TestPerformance

Manyerrors,T-maze

Slowonmotor-skilltest

Slow,spatial-orientationtest

Littleapproachandfollowingbehavior

Slowont-maze

Littleplayfulfightingwithhandler

Poorperformanceonstringpulling,manipulationtest

Littlepersistence,spatialorientation

Manyvocalizations,U-shapedbarrier

Fewescapeattempts,reactivitytest

Fast,goal-orientationtest

Fast,goal-orientationtest

Littleactivityduringbellringing

Littleinvestigation,reactivitytest

Manyerrors,U-shapedbarriertest

Slowonmazetest

BackcrosstoBasenji

33

Aswesawinchapter10,thetrailingtestshowsahighdegreeofvariationineverypopulation,butthedifferencesinvariancebetweenthesepopulationsarealmostentirelyaccountedforbyfearresponsestotheapparatus.Alargeamountofvarianceduetothis


sortoftimidityoccursinthebackcrosstothebasenjis,suggestingthatwemaybedealingwithabackcrosstoarecessive.

AssumingthatwehavesucharelativelysimpleMendelianmechanism,wewouldexpectcertainresultsinafactoranalysis.Thefactor-analyticmethodisbasedoncorrelation,andcorrelationispossibleonlywherethereisvariation.AccordingtoMendeliantheory,thereshouldbegeneticvariationonlyinthebackcrossandF2generations.Therefore,weshouldgetclear-cutgeneticfactorsfromonlythesepopulations.Thisexpectationisborneoutbytheresults,atleastinpart.Inthebackcrosstothebasenjis,thetrailingtesthasthehighestloadingonthegeneralfactormentionedabove.Wecouldthereforecallthisfactor"timidity,orfear,"particularlyofstrangeapparatusbutalsoinvolvingsomefearofhumanbeingsbecauseofthenegativecorrelationwithplayfulaggressivenessandattractiononthehandlingtest.Fearortimidityis,ofcourse,theoppositeendofthescalefromconfidence,whichwastheoriginallabelofthefactorandanequallyappropriateone.Wecannowspecifythekindofconfidence—thatevidentindealingwithstrangeobjects.

Wemayconcludethatthisisacaseofasimilareffectonperformanceinmanydifferentsituations.Thisfitstheconceptofageneralbehaviortraitproducedbyapleiotropicgene.However,withthepossibleexceptionoftheheartratefactor,

apleiotropicgene.However,withthepossibleexceptionoftheheartratefactor,whichmightitselfberelatedtoanothersortoftimidity,apparatus-fearistheonlycaseofthissortwhichturnedupinthefactoranalysis.Therearenootherwell-identifiedfactorsinvolvinglargenumbersoftests,andwemustconcludethatthevastmajorityofgeneticeffectsonbehaviorarehighlyspecificandrestrictedtooneortwosituations.

Re-examiningthecorrelationtables,wewouldexpectthatifgeneraltraitswerecommon,thereshouldbemanyhighcorrelationsinthebackcrossandF2generationasaresultofgeneticsegregation.Withtheexceptionofthetrailingtestscoresandcertainothersderivedfromcommontests,andhencedependentoneachotherforotherreasons,therearenosuchhighcorrelations.Therearemanymorecorrelationsbetweentheindependentteststhanmightbeexpectedbychance,butallofthemarelow.Thisindicatesthattheremaybetraitswhichhavemajoreffectsononetestandonlyminoreffectsonothers.Evaluatingthewholestudy,wecansaythatthemajorityofbehaviortraitsappeartobeofthislatterkind,specificintheireffectsandinheritedindependentlyofeachother,andthattheonlyverifiedgeneraltraitisanemotionalone.

Valueofthefactorialmethodforgeneticanalysis.—Thevalueofthefactorialmethodisthatitselects,onanentirelyobjectiveand


impersonalbasisindependentofthepreconceivedideasoftheexperimenter,thosemeasurementswhichhavecommoncorrelations.Thesameobjectivitycomprisesitschieflimitationforgeneticanalysis,becausethemethodmakesnodistinctionbetweenthosemeasurementswhicharecorrelatedbecauseofheredityandthosewhicharecorrelatedbecauseofvariousenvironmentalagents.Thedistinctionbetweenfactorswhichareprimarilygeneticandothersmustthereforebemadeonthejudgmentoftheexperimenter.

Theessentialcharacteristicofageneticallydeterminedfactoristhatitshouldappearonlyinpopulationsinwhichthereisimportantgeneticvariation.InaMendeliancross,itshouldappearinthesegregatingpopulations,i.e.,thebackcrossesandF2's.Ifthegeneticsysteminvolvesdominance,thefactorwillappearonlyintheback-crosstotherecessive.Aswehaveseenabove,onlyonefactorhadthischaracteristicinanyclear-cutway.

Factoranalysiswillalsoselectmeasurementsmadeinsituationswhichforsomereasonappeartobesimilartotheanimals,whetherornotthesimilarityhasa

reasonappeartobesimilartotheanimals,whetherornotthesimilarityhasageneticbasis.Forexample,boththemotor-skilltestandspatial-orientationtestrequiredclimbingonaramp.Correlationmayoccurbecausetestsareactuallysimilar,asinthiscase,orbecausemeasurementsaremadeatthesametimeandhencearenotcompletelyindependentofeachother.Stillanotherpossibilityistheeffectofprevioussuccess,whichmaycarryoverfromonetesttoanother,whetherornotthetestsaresimilar.Thesekindsofcorrelationsmayinpracticebedifficulttotellfromthoseproducedbygeneticcorrelation.Geneticallybasedcorrelationsshouldappearinonlythesegregatinggenerations,whilenon-geneticcorrelationsmightappearinnon-segregatingpopulationsaswell,inevitablyproducingsomeconfusionbetweenthetwosourcesofcorrelation.

Analyzinggeneticvariancebijcorrelationalmethods.—Analyzinggeneticresultsbythemethodoffactoranalysisisadifficultprocesswithoutadditionalcluesbasedonadirectknowledgeoftheteststhemselves.Thissuggestsanotherpossiblemethodofanalyzinginheritance—onebasedoncorrelation.Ifwetaketwotestswhichshowhighcorrelationinthesegregatinggenerationsandlowcorrelationsinotherpopulations,weshouldbeabletomakeanestimateoftheamountofvarianceduetogeneticfactors,usingtheprinciplethatthepercentageofvarianceduetocorrelationisgivenbythesquareofthecorrelationcoefficient.

AsshowninTable14.10,thismethodcanbeusedtotransform

EFFECTSOFHEREDITY

377

thevarianceofthetrailingtest,thekeyvariableinthe"activeconfidentsuccess"factor,bycomputingthecommonvariancewitherrorsintheT-maze,thetestwithwhichitismosthighlycorrelated.Theresultisadistributionofvariancewhichisconsistentwiththe

TABLE14.10

CommonVarianceinTrailingTestasIndicatedbyCorrelationwithPerformanceinT-Maze

hypothesisofarecessivegeneorgenesfortimidityinthebasenjibreed.Furthermore,theresultsareverydifferentfromtheoriginalrawdata,whichlookedasifthereweremanycomplicatedinteractionsinvolvedwiththe

lookedasifthereweremanycomplicatedinteractionsinvolvedwiththematernalenvironment,etc.Inotherwords,thecorrelationcoefficientcanbeusedto"strainout"thatportionofthevariancewhichconformstothemathematicalassumptionsofthecorrelationcoefficient;namely,thoseofsimplelineareffectsandanormaldistributionofvariation.

Themethodshouldworkwellonlyifthetwotestsormeasurementsusedaresituationallyindependentofeachother,sothattherearenocommonenvironmentalfactorsandcorrelationisduechieflytothehereditaryorganizationofeachindividual.Itshouldalsoworkbestwherenumberslargeenoughtoinsuretheaccuracyofestimatesofthecorrelationcoefficientareused.

Thisagainbringsuptheneedfornewmethodsofanalysis.Asindicatedinchapter12,presentlyavailablequantitativemethodsareinadequateforanalyzingtheeffectsofheredityuponintricateproblem-solvingbehavior,excepttoindicatethatcomplexinteractionisimportant.Progressinthefuturewillinpartdependonthedevelopmentofstatisticalmethodswhoseassumptionsmoreaccuratelymeetthefactsofbehaviorinheritance.However,thereis


alreadyabundantevidencefromourownandotherworkthatheredityhasaquantitativelyimportanteffectonbehavior,andfutureresearchshouldalsobedirectedtowardtheimportantquestionofhowheredityaffectsbehavior—aproblemwhichisstillalmostuntouchedwithrespecttothekindsofgeneticdifferencesinemotionalreactionsandsocialbehaviorwhicharesoimportantinthedog.

CONCLUSION

Inthischapterwehaveattemptedanunbiasedgeneralsurveyoftheeffectofheredityuponthebehaviorofdogs.Whilemanyofthetestsweresetupwithoutanypreviousknowledgeofbehavioraldifferences,manyothersweredevisedtomeasurethebreeddifferencesinbehaviorwhichwehadseenincasualobservations.Inshort,wetriedtodesignourexperimentssothattherewouldbeafavorablechanceofrevealinggeneticdifferences.Thedataarebiasedinthisdirection,butthestatisticalmethodsarenot.

Ingeneral,theresultsshowthatheredityisanimportantquantitativedeterminerofbehaviorindogsandthatgeneticdifferencesinbehaviorcanbeasreliablymeasuredandanalyzedascanhereditarydifferencesinphysicalsize.

measuredandanalyzedascanhereditarydifferencesinphysicalsize.

Consideredasagroup,theresultsofthevarioustestsareconsistentwiththeprincipleofMendeliansegregation,withsomeindicationthatdominanceisanimportantfactorinmostcases.Atthesametime,theresultsofindividualtestsarefrequentlydifficulttointerpretuponasimpleMendelianbasisbecauseofthecomplexinteractionswiththeenvironmentwhicharesoofteninvolvedintheprocessofbehavioraladaptation.

Therearerelativelyfewgeneralbehavioraltraits.Rather,eachbreedshowsacombinationofmanyspecialcharacteristicswhichareoftenrelatedtothespecialbehavioraltasksforwhichthebreedhasbeenselected.

Furthermore,therearerelativelyfewbehavioraltraitsforwhichanybreedisactuallyhomozygous.Evenwithintherestrictedsampleschosenforthisexperimenttherewasagreatdealofindividualgeneticvariability.

Thislargeamountofgeneticvariation,bothwithinandbetweenbreeds,Leadstotheconclusionthatitisimpossibletogeneralizeaboutanyonebreedfromexperiencewithonedogorevenonestrainofdogs,andthatitislikewiseimpossibletogeneralizeaboutalldogsfromexperiencewithonebreed.Furthermore,theirgreatrangeofgeneticvariabilitymakesdogshighlyreactivetoselection.


Selectionofcertainkindsofbehaviorcangreatlymodifyabreedwithinafewgenerations,andincreasingtherangeofvariabilitystillfurtherbybreedcrossingmakesitpossibletoreadilycreatenewanduniquecombinationsofbehavioraltraitstomeetthespecializedneedsofchanginghumansocieties.

GENERALIMPLICATIONS

IMPLICATIONSFORTHEARTOFDOGBREEDING

INTRODUCTION

Ourprimarypurposeinthisstudywastodiscoverasmuchaspossibleabouttheeffectofheredityuponbehavior,andwechosethedogasoneofthemostfavorablespeciesfordemonstratingthemagnitudeofsucheffects.Toachieveourobjectiveitwasnecessarytostudythegeneticbackgroundofdogs,theirbehavioraldevelopment,andtheirsocialorganization.Allthisinformation,togetherwiththefindingsfromourgeneticexperiments,hasimplicationsforthepracticaldogbreederaswellasthescientistandthestudentofhumanaffairs.

Wehaveusedtheword"Art"advisedlyinthetitleofthischapterbecauseanypracticalapplicationofscientificknowledgeinvolvesacertainamountofindividualjudgmentandadaptationtospecialcircumstances.Thescientificfindingsmustbeinterpreted,andwhenthisisdoneweareenteringtherealmofthearts.Applicationsmustbedesignedtoindividualcircumstances.OurownworkwasnecessarilylimitedtoonlyafewoutofthemorethanonehundredbreedsnowrecognizedbytheAmericanKennelClub.Inthefollowingpages,weshalloutlinethemajorfindingsofourstudyandindicatetheirgeneralimplications.

RESULTSANDTHEIRIMPLICATIONS

Basicdogbehavior.—Allpresentevidenceindicatesthatdogswerefirstdomesticatedfromwolvesandthatbothspeciespossessthesamebasicpatternsofbehavior.Muchdogbehaviorcanbe

383

understoodintermsofthesociallifeofwolves,anddogbreedscanbethoughtofasmoreorlessspecializedpopulationsofwolves.Therawmaterialsofthedogbreederarethebehaviorpatternsofdogsandwolveswhicharelistedinchapter3.Hecanmodifythefrequencyofexpressionofthesepatternsinallsortsofcombinationsexceptthosewhichareincompatiblewithlifeandreproduction.Thisgeneralrepertoryofbehaviorlikewiseimposescertainlimitationsuponbreeding,inthatitisdifficult,ifnotimpossible,togobeyondthebasiccapacitiesofdogs.

Combinedactionofenvironmentalandhereditaryfactors.—Wefoundbreeddifferencesinbehaviorbeginningatbirthandextendingthroughoutthefirstyear.Duringthistime,particulardifferencesmightwaxandwaneandenvironmentalfactorscouldaffectbehavioratallstagesofdevelopment.The

environmentalfactorscouldaffectbehavioratallstagesofdevelopment.Theimportantfactisthatbehaviorisneverwhollyinheritedorwhollyacquiredbutalwaysdevelopedunderthecombinedinfluencesofhereditaryandenvironmentalfactors.Theconclusionforthepracticalbreederisthatitisalmostalwayspossibletomodifybehaviorbymodifyingenvironmentaswellasheredity.Sincetheformercanbedonesomuchmorerapidlythanthelatter,itisalwaysagoodideatosupplementabreedingprogramwithoneofimprovedtrainingandupbringing.

Thisbringsupthepracticalquestionofwhetheritisbettertoreardogsinapoorenvironment,withtheideathatonlythebestanimalswillovercomeitandwillbechosenforbreeding,orwhetheritisbettertosetupafavorableenvironmentandselectanimalswhichdobestundertheseconditions.This,ofcourse,isamatterofpracticaljudgment.Theformerplanobviouslyleadstoagreatdealofwaste,anddogsmaybeselectedwhichdowellinpoorenvironmentsbutinnoothers.Ingeneral,thebestplanwouldbetoraisetheanimalsunderthebestpossibleconditionsandbaseaselectionprogramonincreasinglyhigherstandards.

Periodsofdevelopment.—Designingagoodenvironmentforthedevelopmentofapuppydependsuponknowledgeoftheperiodsofdevelopment.Itis,ofcourse,importantatallagestoprovideadequatenutritionandtopreventdisease.Beyondtheserequirementsidealcarevariesfromperiodtoperiod.Intheneonatalperiodanormalmotherwillprovideoptimalcareforherpuppies,andattentionshouldbeconcentrateduponmakingsurethatthebitchiswellnourishedandallowedtocareforherpuppiesundisturbed.Themostthattheownerneedstodoistoinspectthepuppiesonceadaylorpossibleillnessoraccidents.Thisinspectionmayleadtosecondarybenefits.Althoughwehavenodirectevidence,experi-

IMPLICATIONSFORBREEDING385

mentswithotherspecies(Levine,1962;Denenberg,1962)stronglyindicatethatvounganimalsbenefitfromthestimulationofhandling.

Asimilarregimecanbecontinuedthroughthetransitionperiod,anditisnotuntilthebeginningoftheperiodofsocializationthatadditionalcarebecomesimportant.Thefirstthingistoprovideadditionalfood,beginningat3weeksofageorpossiblyearlierifthemotherisshortofmilkorhasalargelitter.

Intheperiodofsocializationtherearetwobasicrulesforproducingawell-balancedandwell-adjusteddog.Thefirstoftheseisthattheidealtimetoproduceaclosesocialrelationshipbetweenapuppvandhismasteroccursbetween6and8weeksofage.Thisistheoptimaltimetoremoveapuppvfromthelitterandmakeitintoahousepet.Ifthisisdoneearlier,especiallyat4weeksorbefore,thepuppvhaslittleopportunitvtoformnormalsocialrelationshipswithotherdogs.Itwillformcloserelationshipswithpeoplebutmavhavedifficultvadjustingtoitsownkindeveninmatingorcaringforpuppies.Ontheotherhand,ifprimarysocializationwithpeopleisputofftoamuchlaterperiod(theoutsidelimitbeingabout12weeks),thesocialrelationshipsofthepuppywithotherdogsmavbeverygood,buthewilltendtobetimidandtolackconfidencewithpeople.Althoughalldogbreedshavethecapacitytodevelopaclosesocialrelationshipwithpeople,theimportanceofthisrelationshipvarieswiththedog'sfutureuse.Astrongrelationshipishighlyimportantwithpetdogs,workingdogs,andthosehuntingdogswhichworkunderclosedirection.Itisprobablynotsoimportantinmosthounds,withwhichthedog-humanrelationshipisnotsoessentialforsuccessfulhunting.

Thesecondgeneralruleisthatthevoungdogshouldbeintroduced,atleastinapreliminarvway,tothecircumstancesinwhichitwillliveasanadult,andthisshouldbedonebefore3or4monthsofage.Theyoungpuppyfrom8to12weeksisahighlymalleableandadaptableanimal,andthisisthetimetolaythefoundationforitsfuturelifework.Dogsleftinakenneluntil4monthsofageorolderarefrequentlypoorlvadaptedtoanvotherlife.ThisconclusionisstronglysupportedbytheworkofKrushinskii(1962)aswellasourown.Althoughanexceptionalanimalorbreedmaydofairlywellwhenthesetworulesarenotfollowed,theirobservancewillbringoutthefullgeneticcapacitiesofamaximumnumberofanimals.

Theimportanceofbreeddifferences.—Thereareimportantbreeddifferencesinalmosteveryaspectofbehaviorandphysique,andeveninthedevelopmentofsocialrelationships.Atthesametime,

thecapacitiesofeachbreedareagreatdealbroaderthanmostpeoplerealize.Abreedmayhaveonehighlyspecializedability,butinmostcasesitalsoretainsbroadandgeneralcapacitiesaswell.Forthepracticalbreederandevenforthepetownerthisfindinghasrelevancetothechoiceofabreedforanyparticularpurpose.Somebreedsarerathernarrowlyspecializedintheirbehavior,par-ticularlvtheworkingdogs,whichoftenmakepoorhouseholdpetsunlesstheyaregivenaratherhighdegreeoftrainingandregulartaskstoperform.Onthe

aregivenaratherhighdegreeoftrainingandregulartaskstoperform.Ontheotherhand,eventhesebreedsretainwiderabilities.Germanshepherdscanbetaughttracking,andcolliesretainanabilitytohuntdeer,asmanycollieownershavefoundtotheircost.

Ingeneral,huntingdogsdobetterinakennelthandotheworkingbreeds.Inourownexperiments,basenjis,beagles,cockers,andterriersalladjustedwelltothelaboratoryconditions.Thesamehuntingbreedsadaptthemselveswellashousepets.Beaglesareafavoriteforthispurposebecauseoftheirextremelackofaggressiveness.Withaminimumoftraining,abeaglewillbecomeabearablehousepet,andthechiefdifficultvwiththebreedundermodernconditionsisinattentivenesstocars,witharesultinghighdeathrate.Ontheotherhand,theydopoorlyastrainedperformers.Otherkindsofhuntingbreeds,suchasthebirddogsandretrievers,alsoadaptwelltohouseholdlivingandusuallyaremuchbetteratacceptinginhibitorytrainingthanthehounds.Thegeneralprincipleisthatmanybreedshaveawiderrangeofadaptabilitythanisordinarilyrecognized,andthatthescopeofadaptabilitymaybemuchnarrowerinsomebreedsthanothers.

Heterogeneitywithinpurebreeds.—Forourpurposesitwasdesirabletominimizevariationwithinbreedsbystartingwithoneortwofoundationpairsineachgroup.Theprocedurewassuccessfulindemonstratingsignificantvariationbetweenbreedsinalmosteverymeasure,buttheprecedingpagesalsodocumentthewiderangeofbehavioralandphysicalvariationwitiiineachbreed.WemayrecallsuchexamplesastheweightofShetlandsheepdogsatoneyear(mean=11.7kg.;range,4.2-31.6kg.)orleash-trainingdemeritsofbasenjis(mean=57;range,20-97).Obviouslyagreatdealofphenotvpicvariationisstillpresentinthepurebreedsofdogs,andthegeneticsourceofsomeofthisvariationisshownbythegeneralfindingthatmatingswithinabreedtendedtobeconsistentlydifferentfromeachodier.Thismeansthatthepracticalbreedercanusuallyeffectmajorchangesinabreedbvmeansofaselectionprogram.Whetherornothewillbesuccessfulinachieving


thechangeshedesireswilldependuponthenatureofhisobjectivesandthedetailsofthebreedingprogram.

Importanceofemotionaldifferences.—Differencesinemotionalreactionsareverycommon,bothbetweenandwithinbreeds.Thishasseveralconsequencesofinteresttothepracticalbreeder.Mostoftheseemotionalreactionsarespecific

ofinteresttothepracticalbreeder.Mostoftheseemotionalreactionsarespecificinnature.Forexample,abasenjiisafraidofstrangeapparatusbutshowslittletimiditywithrespecttootherdogs.Thereappeartobeseveraldifferentkindsoffearfulnessindogs,andselectionforconfidenceinoneparticularsituationwillnotnecessarilyaffectconfidenceinanother.Theproblemofunwantedtimiditypresentsitselfinalmosteverybreed.Itsveryuniversalitysuggeststhatitmaybeatraitnecessaryforexistence.Ananimalwhichisafraidofnothingisnotlikelytolivelongorbeanamenablecompanionforman,andselectionshouldprobablybedirectedtowardadesirablebalancebetweentimidityandoverconfidenceratherthancompleteeliminationofeithertrait.

Emotionalreactionshaveimportanteffectsuponperformance,sothatselectionforabilitytolearnparticulartasksislikelytoaffectemotionsfirstandtruecognitiveabilitieslater.Itissometimesverydifficulttoseparatethetwoinapracticalsituation.

Motivationaldifferences.—Closelyrelatedtoemotionaldifferencesarevariationsindegreeofmotivation.Intermsofpsychologicallearningtheory,repeatedreinforcementofanactbyrewardorpunishmentleadstoincreasedmotivation.Ourfivebreedsdifferedintheirpreferredmodesofreinforcement.Beagles,forexample,werereliablymotivatedbyfood;Shetlandsheepdogsandbasenjiswouldsometimesmerelysniffatthefoodrewardsandweretypicallyhesitantabouteating.Anopportunitytoexplore,particularlyinanodor-richenvironment,appearedmorerewardingtobeaglesthantoShetlandsheepdogs.Differencesinreactiontounpleasantoraversivestimulationwerealsomanifested.Physicalrestraintevokedmorestrugglinganddistressvocalizationinbasenjisthaninwire-hairedterriers,althoughintheirpensbothbreedsappearedtobeactiveandaggressive.Sheltiesarehighlysensitivetopunishment.Hayes(1962)hasgonesofarastosuggestthattheeffectsofgenesuponintelligenceareexertedprimarilythroughmodificationsofthemotivatingpropertiesofparticularclassesofstimuli.

Forpracticaldogbreeders,themostimportantmotivationalcharacteristicofadogisitsresponsetopraiseandblamefromatrainer.Breedvariationsinattractiontohumansdevelopedearlyinourpuppies,asshownbythehandling-testresultsandwereobviouswhenthedogslivedinoutsideruns.Althoughallthedogshadthesame

amountofprevioushandling,spanielsandbeagleswouldtypicallyswarmoveranexperimenterduringtheweeklyexamination,whilebasenjiandShetland

anexperimenterduringtheweeklyexamination,whilebasenjiandShetlandsheepdogsstoodaside.Undoubtedlyselectionforsocialresponsestomanhasplayedanimportantpartindogbreeding.Whenananimalcanbereliablymotivated,ineitherapositiveornegativeway,itsbehaviorcanbemoldedbycontrollingreinforcement,sothatthisaspectofhereditaryvariationinbehaviorhasthegreatestsignificanceinchoosingabreedforaparticulartask.

Heredityandintelligence.—Theinheritanceofthetendencytoperformwellinaparticularsituation,insofarasitcanbeseparatedfromemotionalandmotivationalreactions,appearstobehighlycomplex.Thegeneralprinciplehereisthatproblemsolvingisaprocessofadaptation,andtheanimaluseswhatevercapacitiesithasinordertosolvetheproblem.Thiswasapparentinthedifferentsolutionsoftheproblemofboxclimbinginthemotor-skilltest,inwhichthecockerandbasenjibreedsusedverydifferentcapacitiestoachievethesameresult.Inapracticalprogramofselectionthismightmeanthattwodogshavingverydifferentbasiccapacitiesbutequalperformancemightbeselectedandmatedtogether,givingrisetooffspringwithstillothercombinationsofabilitieswhichmightbeinferiortoeitherparent.Anyrealprogressinsuchasituationwoulddependonanalysisofthebasiccapacitiesinvolvedandinde-dendentselectionforeach.

Indogswefoundnothinglikethegeneral-intelligencefactorsometimespostulatedforhumans.Thisfailuremighthavebeenduetoinadequatescopeoftesting,sincethedimensionsofintelligencewerenotthemajorgoalsofthestudy.Ourresultsare,however,compatiblewiththoseofSearle(1949),whofoundthatratsselectedforgoodperformanceononetypeofmazeperformednobetterthantheaverageonotherlearningtasks.Provisionally,wehaveadoptedtheviewthatgeneticeffectsinspecializedtasksaremediatedthroughnumerousindependentpathways,andthatselectionforgoodperformanceononetaskwillimproveonlyverycloselyrelatedtasks.Theunityormultiplicityofintelligence(fromthegeneticpointofview)wasnotcriticallytestedintheseexperiments,andmoreresearchisneededtosettletheissue.Itseemspossiblethatsincecertainpsychologicalprocesseshavebeenshowntobecriticallydependentupontheintegrityoflocalizedportionsofthebrain,theseorotherpsychologicalprocessesmightbecontrolledbyaparticulargroupofgenes.Itshouldeventuallybepossibletodescribeanyspecificproblem-solvingabilityinthedoginterms


ofafewbasiccapacities,butatpresentwecanspecifyonlyafewofthese

ofafewbasiccapacities,butatpresentwecanspecifyonlyafewoftheserelatingtoemotionalandmotivationalresponses.

Traitindependence:lackofcorrelationbetweenphysicalandbehavioralmeasures.—Oneofourmajorfindingswasanegativeone,thefailuretofindcorrelationsbetweenphysicalandbehavioralmeasures.TheF2basenji-spanielhybridsdemonstratedthisbest.Theseanimalsshowedawiderangeofvariabilityinappearance,noneshowingexactlythesamecombinationsofcharacteristicsastheparentbreeds.Thephysicalphenotypeyieldednocluestotheresultsofthebehavioraltests.Thedogwithbasenjicoatandtailcarriageoftenwasdocileliketheaveragespaniel.Althoughsomeheritablevariationinbehaviorobviouslyrestsuponheritablestructuralcharacteristics,suchaslengthoflegsandlopears,mostifnotallbehaviorisunrelatedtothecolorandformcharacteristicswhichdefinethecommonimageofabasenjiorcockerspaniel.Therefore,attemptstocharacterizeabreedbiologicallyandpsychologicallywithrespecttoatypeembodiedinaparticularindividualareunsound.Thedefinitionofatypehassomevalueintheshowring,becauseitgivesjudgesanobjectivebasisforscoringacompetitiveevent,butitshouldberecognizedasanabstraction.Abreedisnotdefinedbyconformitytotype,butbycommonancestryandabsenceofoutbreeding.Ifconformitytotypeisestablishedasthegoalofaselectivebreedingprogram,certaindifficultiesareboundtoappearbecauseofthecomplexityofgeneticdeterminationofthemanytraitswhichenterintoatypedefinition.

Inheritanceofcoatcolorandbodystructure.—CloselyassociatedwiththebehaviorresearchprojectC.C.Little(1957),buildingonthepreviousworkofothers,workedoutthemajoroutlinesofcolorinheritanceinthedog.Inmostcasescolor,hairlength,andhairtexturearedeterminedbymajorgeneswithclear-cutdominanceandepistaticrelationshipsbetweenthem,withsomeminormodifyinggenes.Thismakestheselectionofadesiredcolorafairlyeasyprocess.Sizeandphysicalconformationareapparentlydeterminedbymultiplefactors,butsincethesecharacteristicscanbeeasilyquantified,thisdoesnotinterferewithselection.

Theinheritanceofstructuraldefectsislesswellknown.Thepurebreedsusuallycontaingeneswhichproducephysicaldefects.Cleftpalate,hipdysplasia,blindnessproducedbyprogressiveretinalatrophy,andhemophiliaareallknowntobeatleastpartiallycausedbyheredity.MoreextensivelistshavebeenmadebyBurns(1952)andFuller(1954,1956a,1960).Inourownparticularstrainswefoundcasesofundershotjawsandatendencytoinguinalherniain

thebasenji,otocephaly("pigjaw")inthebeagles,low-degreehydrocephalyincockers,obesityandmonorchidisminshelties,andclubfeetinwire-hairedterriers.Infertileindividualsproducedbyvariousphvsiologicaldefectsshowedupinallthestrains.

Someoftheseconditionsarerareandareseldomseenbytheordinarybreeder;othersarecommonenoughtocauseconcernamongbreedassociations.Theirgeneticmanagementdependsuponthemodeofinheritance,thefrequencyofthedefect,itseconomicimportance,anditseffectuponviabilityandfertility.Mostbreederswillfinditdesirabletoconsultageneticistforadviceonspecificproblems,butafewexampleswillillustratethedifficultiesinvolved.

OurShetlandsheepdogsillustrateasimpletypeofproblemanditsgeneticmanagement.SomeofthemcarriedthedominantMgene,whichchangesblackhairtograywithblackspots.Inthepropercombinationwithothergenes,itproducesthehighlyadmiredbluemerlecolor.Amerleisalwaysheterozygous(Mm),sinceMManimalsarenotbluebutalmostcompletelywhiteandpartiallyblindanddeaf.PreventionofthedefectiseasilyachievedbynotallowinganytwoanimalscarryingM,whethermerleorwhite,tomatewitheachother.Aslongasoneparentismm,nodefectivewhiteswillbeproduced.

Otherdeleteriousgenesarenotasreadilymanaged.Scatteredamongthedogbreedsaremanyrecessivegeneswhichproducenoobviousphenotypiceffectsexceptindoubledose.Manyofthesegenesarequiterareandthedefectscorrespondinglyinfrequent,butunderspecialcircumstancesaparticulargenemaybecomecommon.Progressiveretinalatrophvleadingtoblindnessissuchacondition.Incertainbreedsafewpopularstudmalesapparentlycarriedthegeneanddisseminateditsowidelvamongnumerousdescendantsthatblindnesshasbecomeaseriousproblemforthebreedassociations.Theonlywaytoeliminatethegeneisthroughbreedingtests.Withoutthem,itisimpossibletodistinguishbetweencarriersandnon-carriers.Testmatingstoablindanimalmustbemadeandtheproductionofsixorsevennormal-sightedpuppiestakenaspresumptiveevidenceofthegene'sabsence.Suchaprocedureisinevitablytimeconsumingandexpensive.

Somephysicaldefectsconsistentlyappearincertainstrainsbutfollownoregularpatternofinheritance.Thusoccasionalcasesofcleftpalateappearedinourbeaglesandclubfeetinourwire-hairedfoxterriers.Suchcasescanbeaccountedforbyageneticconstitutionsensitivetoharmfulenvironmentalinfluences;themoresensi-

influences;themoresensi-

tivethegenotype,thelessenvironmentaldisturbanceisneededtoproducetheanomalv.

Thepublisheddataonhipdysplasiaindicatethatitisanenvironmentallyinfluenceddefectwithimportanthereditarydeterminants(Fuller,1960).Vulnerabilityrunsinfamilies,butthedegreeofafflictionissovariablethatprecisegeneticpredictionscannotbemade.AsurveyofthreebreedsbeingrearedaspotentialguidesfortheblindshowedthatoffspringofparentswithgoodhipspracticallyneverhaddysplasiaasjudgedfromX-rayphotographs;ontheotherhand,parentswithpoorhipsmighthavesatisfactoryoffspringbutproducedmorethantheirshareofdefectivepups.Inaddition,itappearslikelythatmorethanonegeneisconcerned.

Thepracticalgeneticmanagementofsuchamultiple-factordefectofmoderateheritabilityis,however,reasonablysimple.Itconsistsofbreedingfromthebeststockavailable,selectingthoselinesinwhichthedefectappearsinfrequently,anddisregardingrarecasesofdefectswhichmayresultfromenvironmentalcauses.Themethodisnotinfallible,butitshouldproducedesirableresultsunlessalltheavailablebreedingstockarecarriersofthedeleteriousgenes.

Forthepracticalbreederthewidespreadoccurrenceofinheritedphysicaldefectsmeansthatanyprogramofselectionmustbebasedonmultiplecriteria.Itisofnousetoproduceahighlyintelligentdogifheisalsoinfertile.

BREEDANDSTRAINIMPROVEMENT

Selection.—Themajorresourceoftheanimalbreederisselection,whichimpliesbothadesiredobjectiveandtheprovisionofastandardizedrearingproceduretominimizeenvironmentalvariation.Selectionhasbeentreatedbyanumberofauthorsfrombothpracticalandtheoreticalpointsofview(Lush,1943;Lerner,1958;Falconer,1960).Basically,selectionisanattempttobringaboutthedifferentialreproductionofgenotypes,andsochangetherelativeproportionsofalternateallelesfromgenerationtogeneration.

Theresultsofselectiondependchieflyuponthedegreeofheritabilityandthemodeofinheritanceofthedesiredtrait.Asshowninchapters12and14,heritabilityestimatesbasedonthefivepurebreedsandcrossesbetweentwoofthemrangebetweenzeroand66percent,withanaverageof27percent.Heritabilityestimatesontraitsvaluableinlivestockproduction,suchaswool

Heritabilityestimatesontraitsvaluableinlivestockproduction,suchaswoollengthor

eggproduction,rarelyrunover60percentandoftenaremuchlower(Falconer,1960).Ontheaverage,therefore,behaviorindogsshouldbeasresponsivetoselectionasarephysicaltraits.

Ofcourse,theaveragebreederismorelikelytobeworkingwithapurebreedthanwithhybrids.Evenheretheindicationsarefavorable,sincethebetween-matingvarianceaveraged12percentinasampleinwhichthiskindofvariancehadbeendeliberatelyreduced.Theamountofvarianceavailableforselectioninanunrestrictedsampleofapurebreedmustbemuchgreater.

Theotherfactoronwhichthesuccessofselectiondependsisthemodeofinheritance.Ifinheritanceissimple,resultswillbeachievedveryrapidly.Forexample,selectionforaneffectproducedbyasinglerecessivegene,suchasthenon-merlecondition,canproducemaximumeffectsinonegeneration.Ontheotherhand,ifaneffectdependsuponacombinationofseveralgenes,whichmayinteractwitheachother,resultswillcomemuchmoreslowly.Ourevidenceindicatesthatthemodeofinheritanceofdifferencesinemotionalreactionsandrelatedsimplebehaviorpatternsisrelativelysimple,whereasthebehaviorinvolvedinproblemsolvingandothercomplextasks,whileequallyheritable,isgovernedbycomplexmodesofinheritance.Tothenumerouspossibilitiesofinteractioningenephysiologyareaddedtheenormouspossibilitiesofinteractiononthebehaviorallevel;theanimalorganizesitscapacitiesindifferentwaysdependingonthetaskathand.Selectioninsuchacasewillbebasedonthebestcombinationofgenespresentintheoriginalpopulation,andLush(1943)makesthesuggestion,basedontheearlierworkofWright(1935)thatitmaybeverydifficulttogetawayfromthiscombinationandmakefurtherprogress,withoutaddingnewcombinationsofgenesthroughoutcrossing.

Allinall,selectionforbehaviortraitsinthedogshouldgivemostrapidresultswhenappliedtoemotionalandmotivationaltraitsandsimplebehaviorpatterns.Thefinalproblemofselectionis,ofcourse,thatofselectingformanytraitsatthesametime,andthisisanimportantpracticalproblemforanybreeder.

Hybridization.—Thewell-knowneffectofhybridvigorcanbeutilizedindogsaswellascorn.Hybridizationisessentiallyatechniqueofreliablyproducingahighlydesirablecombinationofgenes.Itdependsuponmaintainingpurestrainsand,attheoutset,uponhavingalargenumberofparentstrainsfromwhichtochoose,sothatthebestcombinationofparentscanbeselected.Thetechniqueis

choose,sothatthebestcombinationofparentscanbeselected.Thetechniqueiscomparabletothatof"nicking,"aphenomenoninwhichacrossbetweentwospecificindividualsproducesunusuallydesirableoff-


spring.Thehybrideffectcannotbemaintainedbeyondonegeneration,asisalsotruewithnickingbetweenindividuals.

ThepleasingqualityofFihybridsfromcockersandbasenjissuggeststhatbreedintercrossesmightbeusedtoproducesuperiorworkinganimals,justashybridcornisusedinagriculturetoproducesuperiorgrain.Ifthereareobjectionstocrossingbreeds,separatelineswithinalargebreedmightbedevelopedtoseryethesamepurpose.Themethodwouldprobablybemoreeffective,however,withthewiderdifferencebetweenparents,andweseenoreasonforthenon-acceptanceofplannedhybridmatingsoncetheirpurposeisunderstood.

Methodsfortheindividualbreeder.—Theuseoftheabovetoolswillofcoursedependagreatdealupontheobjectivesandresourcesofeachbreeder.Anindividualownerusuallyhasalimitednumberofanimalsathisdisposalandcannotaffordthe10or15yearsnecessarytoaccomplishaselectionprogram.Asstatedabove,mostofthebehaviorconcernedwithcomplexperformancedependsuponacombinationofalargenumberofgeneticcapacities.Theindividualbreederwillusuallyfindthatthebestchanceofgettingsuchcombinationswillbetotryoutvariousmatingswithinhisownstockandotherstocksaccessibletohim.Onceamatingisfoundwhichproducesahighproportionofdesirablepuppies,thebreedercanthenrepeatthismatingthroughoutthelivesoftheparentanimalsandobtainalargenumberofoffspring.Thisgeneralplan,basedon"nicking,"issuitableforthebreederwithlimitedresourcesandtime.

Methodsforbreedassociations.—Thebreedassociationswerefoundedinordertoovercomethelimitationsimposedupontheindividualbreeders,anditispossibleforthemtoaccomplishmuchmorethroughlong-continuedselectionprograms.Inthefuture,thebreedassociationscanaccomplishmorethantheyhaveinthepastbymodifyingtheirobjectivesandmakinguseofnewergenetictheoriesandtechniques.Firstofallitshouldberealizedthatabreedisapopulationofindividualsshowingalimitedbutstillimportantdegreeofgeneticvariability.Ifselectionisconfinedtoonenarrowlydefinedtype,theresultwillalmostinevitablybetheaccidentalselectionofvariousundesirablecharacteristics.Breedstandardsshouldincluderegulationsrelatingtohealth,

characteristics.Breedstandardsshouldincluderegulationsrelatingtohealth,behavior,vigor,andfertilityaswellasbodyform.Thesecanperhapsbestbeaccomplishedbyintroducingtestsofperformanceandemotionalreactionsaswellasappearance.Obediencetrialsandfieldtrialsareavaluablestepinthisdirection.

Thedesirabilityofmultiplestandardsmakesthepracticeofbreedingachampiontoalargenumberoffemaleswithinabreedaquestionableone.Almosteveryanimalcarriessomesortofinjuriousrecessivegenes,andthispracticeinsuresthattheywillbespreadthroughoutthewholebreed,withresultingdisappointmentasthedescendantsofthesechampionsareeventuallybredtogetherandtherecessivetraitsbegintoshowupinlargenumbers.Thebreedobjectivesshouldnotbethedevelopmentofasingle,fixedtype—somethingwhichisonlypossiblebystrictinbreeding—butratherforthedevelopmentofapopulationvaryingwithindesirablelimitsandwithinwhichnewandmorevaluablecombinationsofgeneswillalwaysbepossible.

Thebreedingofworkingdogs.—Dogsstillperformmajorservicesasstockherders,asguidedogs,andaspoliceandguarddogs.Breedingimprovedanimalsforsuchdutiesinvolvesselectionbasedonmultiplecriteria,includingbehavior,fertility,vigor,andspecialphysicalattributesofsizeandstrength.

Anotherimportantconsiderationisthemaintenanceofuniformrearingandtrainingconditions,whichshouldbethebestavailable.Otherwise,variationbetweenindividualsmaydependasmuchormoreupontheearlyenvironmentoftheanimalasuponitsheredity.Asafirstconsequenceofaselectionprogramforgoodperformance,wewouldpredictrapidchangesinemotionalreactions.Second,becauseselectionmustbemadeonthebasisofperformanceofacomplextask,andbecausesuchaperformanceislikelytorestonaparticularcombinationofgenes,onewouldexpectthatcontinuedselectiononthisbasiswouldsoonleadtoastandstillinprogress,andthattherewouldbegreatdifficultyinfixingthedesiredgeneticcombination.Progressshouldbemademostrapidlyiftheabilitytoperformcanbebrokendownintospecificcapacitieshavingareasonablysimplegeneticbasis.Otherwise,thebreedershouldcombineselectionwithoccasionaloutcrossesinordertobringinnewcombinations,repeatingthosematingswhichappearmostsuccessful.Alargenumberofanimalsmustbeavailabletocompensateforwastefromunsuccessfulmatings.

Dogsforresearch.—Themanyadvantagesofpurebreddogswhoseentirelifehistoryisknownareobvious,andtheuseofsuchanimalsisincreasingrapidly

historyisknownareobvious,andtheuseofsuchanimalsisincreasingrapidly(Scott,Ginsburg,etal.91962).Wehavealreadypointedoutthenecessityforthesocializationofkennel-raisedanimals.Laboratory-raisedpuppiesmustalsohavetheopportunityforsocializationatthepropertimeiftheyarenottobe-


comefearfulanduntrainable.Inaddition,theyhavethesamerequirementsforfoundationtrainingandearlyintroductiontotheenvironmentinwhichtheyaretoliveasdootherdogs.Asaminimum,suchpuppiesshouldbegivenelementaryobediencetraining,includingleashandsittraining,andanintroductiontothelaboratoryrooms,beforetheageof3or4months.

Thechoiceofbreedsdependsupontheresearchobjectives.Beagleshavebeenwidelyused,andsomeworkershaveadvocatedthatthisbreedbeadoptedasthelaboratorydog,inthesamewaythatpsychologistsusedtouseWistaralbinoratsasthestandardlaboratorystrain.Therearegoodreasonsforthechoice.Ashuntingdogs,beaglesdowellinkennelconditions.Theyareofmediumsizeandinexpensivetofeed.Havingbeendevelopedprimarilyasahuntingratherthanashowbreed,theyretainagreatdealofvigor.Theyhaveshorthair,andthereforerequirelittlegrooming.Finally,theyareoneoftheleastaggressiveofdogbreeds,sothattheycanbehandledsafelywithaminimumoftraining.Atthesametimeitshouldberememberedthatbeaglesarenotauniversaldoganymorethananyotherbreed,beingspecializedinmanyways.Toadoptonebreedasastandardlaboratoryanimalwouldbetothrowawayoneofthemainscientificadvantagesthatdogspossess—theirenormousgeneticdiversity.Forpurposesofexperimentalsurgery,forexample,someofthelargerbreedsaremoreuseful,andforpurposesofstudiesofbehaviorthehighlytrainableworkingbreedsaremoreinteresting.Inlong-termexperimentswhichrequireahighdegreeofco-operationandcontrol,trainedworkingdogswouldhaveobviousadvantages,anditshouldberememberedwhenselectingabreedthatdogsingeneralarehighlyadjustableandadaptableanimals.Almostanybreedcandowellinalaboratoryenvironmentprovidedcertainadjustmentsincareandtrainingaremadeforthatparticularbreed.

ThevigorofFihybridsbetweenthepurebreedsrecommendstheiruseinmanylaboratorysituations,andtheirnatureneedstobeexplored.Eachnewhybridisessentiallyanewbreed,asitwillpossessnewcombinationsofcharacteristicsdependingonwhethertheparentaltraitsareinheritedasdominantsorrecessives.OurFicocker-basenjihybridswerelikebasenjisintheirabilitytoclimb,likecockersintheirresponsetofood,andintermediatewithrespecttobarking.New

cockersintheirresponsetofood,andintermediatewithrespecttobarking.Newcharacteristicsarealsopossiblethroughinteractionbetweennewcombinationsofgenes.

Finallythereisapossibilityofcreatingnewbreedsespecially

selectedforresearchpurposes.Inthiscaseitwouldbewelltostartwithhybridsbetweentwoormorebreedsinordertoobtainthemaximumadvantagesfromvariation.

SUMMARY

Thetoolsoftheanimalbreederareimprovementoftheenvironment,geneticvariation,selection,andhybridization.Theresultsoftheexperimentsdescribedinthesepageshavebeentosharpenthesetoolsratherthancreatenewones.Ourexperimentshaveledtoimportantwaysofimprovingtheearlysocialenvironment,particularlybytakingadvantageofcriticalperiodsindevelopment.Wehavefoundthatgeneticvariationishighlyimportantwithinbreedsaswellasbetweenthem,sothatitshouldbepossibletotransformastrainwithinabreedintoaverydifferentsortofanimalwithinafewgenerations.Themostimportantgeneticdifferencesinbehaviorappeartobeemotionalandmotivationalratherthanthoseofcognitionorbasicintelligence.Suchtraitshaveimportanteffectsuponanytypeofperformanceandshouldrespondrapidlytoselection,providedtheanimalsareraisedunderuniformconditionsminimizingenvironmentalvariations.Superficialappearanceisnoguidetobehavior,andtheuseof"markergenes"consequentlyhaslittlevalidity.Finally,anyselectionprogramleadingtotheimprovementofbehaviormustofnecessitybeonewhichinvolvesmultiplecriteriaincludinggeneralphysicalandreproductivefitness.

Ourtwomajorexperiments,breedcomparisonandbreedintercrossing,donotinthemselvesyieldablueprintfordogbreeding,buttheydofurnishguidesforpersonsinterestedinselectingforbehavioralcharacteristicsorinproducingworkingdogs.Theauthorshopethatthisby-productoftheirresearchwillbeofvaluetothelargegroupwhofindpleasureintryingtounderstandman'sfour-footedcompanion.Aswillbeseeninthenextchapter,anunderstandingofdogsalsohelpsthosewhosechiefinterestisunderstandingman.

THEEVOLUTIONOFDOGSANDMEN

INTRODUCTION

Whendogswerefirstdomesticated,someeighttotenthousandyearsago,theybecameapartofhumansociety,andtheyhavesinceundergonemostoftheculturalandenvironmentalchangesthathaveaffectedtheirmasters.Dogs,however,haveshorterlivesthanmen,andtheygothroughnewgenerationsattheapproximaterateofoneineverytwoyearsinsteadofman'soneintwenty.Wecanroughlyestimatethatdogshavegonethroughsomefourthousandgenerationssincetheirdomesticationwhilemanhasgonethroughonlyfourhundred.Thesefactssuggestahypothesis:thegeneticconsequencesofcivilizedlivingshouldbeintensifiedinthedog,andthereforethedogshouldgiveussomeideaofthegeneticfutureofmankind,alwaysassumingthattherearenoradicalnewchangesintheconditionsofhumanliving.Inshort,thedogmaybeageneticpilotexperimentforthehumanrace.

HISTORICALPERSPECTIVE

Wolvesandmenhadmuchincommonevenbeforedomesticationtookplace.Justasthelioninthesouthernhemisphereoccupiedtheecologicalpositionofthedominantcarnivorepreyingontheherdmammals,sodidthewolf,Canislupus,inthenorthernone.Onceearlymenhadinventedthespearandthebowandarrow,theytoocouldsuccessfullyattackandpreyuponthelargeungulatessuchasdeer,mountainsheep,andbison.StoneAgehuntingtribessoonfoundthemselvesindirectcompetitionwithwolvesforsimilarprey.

Furthermore,aswehavepointedout,bothwolvesandmenaresocialspecies,showingagreatdealofco-operationandmutually

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helpfulbehaviorwithintheirowngroups.Finally,asanecologicallydominantanimal,withnoothercompetitorsexceptman,thewolfshowssomepolymorphism,ashumansdo,inadditiontotheusualdivisionofsocialanimalsintomales,females,andyoung.Wildwolvesshowenoughvariationinform,color,andbehaviorthatMurie(1944)couldeasilyrecognizeeachmemberofawildwolfpack.

Adaptiveradiation.—Whenananimalspeciesmovesunopposedintoanewenvironment,thereisanopportunityforveryrapidgeneticchange,becauseeachsmallgrouppopulatesalargeareawithitsowndescendants,whichinturnreflecttheindividualgeneticpeculiaritiesoftheirparents.Atthesametime,thereisarapidselectionforthoseanimalsbestadaptedtothenewareas.The

thereisarapidselectionforthoseanimalsbestadaptedtothenewareas.Thewholeprocessiscalledadaptiveradiationandisthesortofthingwhichoncehappenedtothewholeclassofmammalsafterthereptileshadbeeneliminatedaspossiblerivals.

Adaptiveradiationonasmallerscaleseemstohavetakenplacesoonafterthedogbecamedomesticated.Withinthevarioushumansocieties,dogsfoundawholenewhabitat.Thedog,asoneofthefirstdomesticanimals,wasaremarkablesocialinvention,bothforprotectionandasanaidtohunting,andeverytribemusthavewantedtogetholdofone.Inthiswaydogsspreadrapidlyovertheworld,differentiatingastheymoved,andsoproducedthesouthernshort-hairedvarietieslikethedingoand,attheoppositeextremeoftheirrange,thenorthernEskimodogswhicharealmostlikewolves(seeFig.2.2).Afurthermultiplicationofhabitatswasprovidedwhentheherdanimalsweredomesticated.Nowdogswereneededtoprotecttheseherdsagainsttheirowncloserelatives,thewolves,whichfoundthedomesticbeastseasyprey.

Thedomesticationofanimalsandplantsproducedanothermajorenvironmentalchange.Huntingwasnolongeraprimaryoccupation,butasportandfrequentlyaluxuryoftherich.Underthesecircumstancesdogsbecamespecializedforthehuntingofmanydifferentanimals.Stillanotherexpansionofhabitatsoccurredaftertheindustrialrevolution,withtheuseofdogsaspetsandsocialcompanionsforcitydwellers.However,noneoftheselaterdevelopmentshadtheimportanceofthefirstmajorexpansionintothenewenvironmentprovidedbyhumansocieties.

Periodofisolation.—AsWright(1950)andothergeneticistshavepointedout,anidealsituationforrapidgeneticchangeisoneinwhichapopulationisdividedintosmallsubpopulationswithcontactspermittingoccasionalgeneexchangesbetweenthem.When

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dogswerefirstdomesticated,thiswasstillthesituationinthemajorityofhumansocieties,whichweredividedintosmallsemi-isolatedtribes,stillreflectingtheconditionswhichhadledtotheveryrapidbiologicalevolutionofmodernmaninthepreviousfiftythousandyears.

Dividedamongtribes,dogsweremaintainedinevensmallersocialgroupsthantheirmasters,withonlvoccasionalopportunitiesformixingwithanimalsfromadjacenttribes.Undertheseconditionswewouldexpectrapiddifferentiation

adjacenttribes.Undertheseconditionswewouldexpectrapiddifferentiationbetweensubpopulations,andthiswasprobablythefoundationofthemajorbreeddifferences.HistoricalrecordsofAmericanIndiantribesshowthateachonehaditsownparticularbreedofdog,perhapsnotverydifferentfromthatoftheneighboringtribebutgreatlydifferentfromthoseatlonggeographicaldistances(Allen,1920).UndersimilarconditionsinancientEurasiathereoriginatedthelargewardogsofonetribe,thelong-leggedgreyhoundsusedforhuntinggazellesonthedeserts,andtheshepherddogsusedtoguarddomesticflocks.

Periodofpanmixis.—Theperiodoflocalisolationwassucceededbyoneinwhichnewmethodsoftransportationbroughtexplorersandimmigrantstogetherfromallovertheworld.WherevertheEuropeanexplorerswent,whetherfortrade,discovery,orwar,theybroughttheirownbreedsofdogs,whichreadilyinterbredwiththenativevarieties.Sometimesthenativebreedsdisappeared,astheydidinAmericaandSouthAfrica.SometimestheEuropeansbroughtnewbreedsbacktotheirshores,asthecrusadersbroughtthegreyhoundsbackfromtheMiddleEast.Ineithercase,thiswasaperiodofmixingandcrossing.

Periodofgeneticcontrol.—Theideaofintensifyingandpreservingdesirablecharacteristicsindogsthroughscientificbreedingishardlymorethanacenturyold,thefirstdogshowhavingbeenheldinNewcastle,England,in1859(Ash,1924).Beforethistimedogsweremainlyproducedandbredonthebasisofresults,nomatterwhattheirancestorsmightbe.Inthelatterpartofthe19thcenturypeoplebegantoappreciatethepossibilitiesofartificialselectionandbegantryingtokeepdogpopulationscompletelyseparateinthemodernpurebreeds.Theseattemptsatgeneticchangeandimprovementwerenotalwaysscientificorcompletelyeffective,buttheyhaveresultedinanewdiversityofdogpopulations.Manyofthemodernbreedswereoriginatedwithinthepastcentury,havingbeenproducedbycrossingolderbreedsandthenselectingtheirdescendantsforspecialcharacteristics.

Geneticchangesinhumanpopulations.—Thefirstthreeofthe

aboveperiodscanalsobefoundinthehistoryofhumanpopulations,althoughextendedovergreaterlengthsoftime.Themodernhumanraces,withlighterskinnedpeopleconcentratedtowardthenorthernpolarregionandthedarkeronestowardtheequator,probablyrepresenttheresultofanancientperiodofadaptiveradiation.Theperiodofisolationintosmalltribeswasonewhichbegantodisappearwiththedawnofcivilizationsomeeightortenthousandyearsago.Aspeoplemovedintocities,theybegantoliveinlargerpopulations,andthesepopulationsbegantobecontinuouswithandmixwithadjacentones.Inmoderntimesthisprocessofpanmixisisstillaccelerating,withpeoplemovingrapidlyovercontinentsandtheentireworld,leavingtheirdescendantseverywhere.

Aperiodofscientificbreedingofhumanpopulationsisyettocome,butthebeginningsarealreadybeingmade(Hammond,1959;Reed,196-3).Asweaccumulateauthenticinformationabouttheinheritanceofgeneticdefectsandotherqualities,prospectiveparentsarebeinggivenadviceaffectingtheirdecisionstohavechildren.Moreover,whetheritisbasedonscientificinformationornot,theculturalhabitoffreechoiceinmarriageleadstoassortivemating.Thereisconsequentlyastrongcorrelationbetweenbodysize,appearance,andevenintelligencetestsbetweenhusbandsandwives.Whatdoesthefuturehaveinstore?Onepossibleanswerisgivenbythecaninepilotexperiment.

THERESULTSOFGENETICCHANGE

Diversityofformandbehavior.—Ourfirstproblemistoassesswhathashappenedtothedogasaresultoflongmembershipinhumansociety.Themostobviousthingisanextraordinarydiversityofformandbehavior.Wenowhavedwarfbreedswhichweighlessthanfourpoundsatmaturity,andgiantbreedsliketheGreatDanesandSaintBernardswhichweighatleastasmuchasthelargestnorthernwolves.Thereareallsortsofvariationsinhairstructureandcolor.DensityrangesfromnearabsenceintheMexicanhairlessbreedtoheavycurlsintheevergrowingcoatsofpoodles.Hairmaybewiryorsilkv,curlyorstraight,andappearinalmostanycolorofthevisiblespectrumwiththeexceptionofgreen.Earscanbeerectordroopingandallgradationsbetween.Tailscanlieshortorlongandvaryfromasickleshapetoatightcurl.Legsalsocanbeshortorlong,andtheskullcanbedeformedandshortenedasinbulldogs,orlongandnarrowasinthegreyhounds.Theonlythingwhichremainsrelativelyinvariableisgeneralbodvform.Asidefromocca-

sionalobeseindividuals,allbreedsretainthelargechestandthinwaistoftheirancestors.

Suchwidevariabilityisalsocharacteristicofhumanbeings,amongwhomthereiswidevariationofskinandhaircolor,shapeoffacialfeaturessuchasearsandnose,and,unlikedogs,ingeneralbodyproportions.Ifhumanbeingsaremorevariablethandogsinsomeways,theyarelesssoinothers.Forexample,aGreatDanemayweighfortytimesasmuchasaChihuahua.Nothinglikethisextremediversityisfoundinthehumanspecies,wherethelargestadultsmaybeonlyfourorEvetimesheavierthanthesmallest,exceptforcasesofextremeobesityanddwarfism.

Thisgeneticdiversityofmen,dogs,andotherdomesticanimalscontrastsgreatlywithwhatweseeinmostwildanimals.Itisalmostimpossibletotellonesquirrelfromanotherofthesamespeciesbyoutwardappearance.Infact,thisdifficultyoftellingindividualsapartisoneoftheperpetualproblemsofstudyinganimalsociologyundernaturalconditions.Weassumethatuniformityisaresultofnaturalselection;thatmutationswhichproducewhitespotting,forexample,makeasquirrelsoconspicuousthatheismuchmorelikelytobetakenbyapredatorthanarehisstandard-coloredrelatives.

Inaspeciesnotsubjectedtointensiveselectionbypredators,agreatervarietyofindividualscansurvivewithoutdifficulty.Furthermore,inahighlysocialanimalmanysortsofnewvariationswillbeprotectedbygroupaction.Inshort,theconditionofbeingahighlysuccessfulsocialspeciesautomaticallyresultsina

conditionofbeingahighlysuccessfulsocialspeciesautomaticallyresultsinarelaxationofnaturalselection,permittingagreatervarietyofindividualstoexist.

Wemaywonderwhythetendencytowarddiversityhasgonetogreaterlengthsinthedogthaninman.Therearetwopossiblereasons.Oneisthatthedoghashadmoregenetictime,intermsofgenerations,toshowtheeffectsofrelaxednaturalselection.Theotheris,ofcourse,thatpeoplehavedeliberatelypreservedandmultipliedharmfulcaninemutationsasobjectsofcuriosity,inawaywhichhasneverbeendonewithhumanmutants.Wemightthenconcludethatthedogisgeneticallyweakcomparedtotheancestralwolf,andthatweoughttoattempttorestorethemoreuniformappearanceandgreatervigorcharacteristicoftheseancestralanimals.Isthisconclusionreallyjustified?

Modificationoffertility.—Comparedwiththewolf,dogsaregenerallymorefertilethantheirwildancestors.Wolvesmatureattwoyearsofageandsometimeslater,andtheaveragelittersizeisfourorfive.Thisprobablyrepresentsthenumberofanimalswhichcanbesuccessfullyrearedtomaturityundernaturalconditions,

wherefoodmustbeprovidedbyhunting.Dogsofmostbreeds,ontheotherhand,becomesexuallymaturebeforeoneyearofageandhavedevelopedatwice-yearlybreedingcycleinsteadofanannualone.Thismeansthatapairofdogshasthepotentialityofproducingtwiceasmanyoffspringasapairofwolves.Medium-sizedbreedsusuallyproducelittersaboutthesamesizeasthoseofwolves,butthelargerbreedsexceedtheproductionofwolvesontheaverage.Againstthis,thedwarfbreedsproducesmalleraveragelittersthandowolves.Also,whilewehavenostatisticsonthis,thereareprobablymorecasesofcompleteinfertilityamongdogsthanamongwolves.

However,wecansayingeneralthatdomesticationandbecomingapartofhumansocietieshasnotonlyextendedtherangeoffertilityindogsbutactuallymadedogsmorefertilethantheirancestors.Suchhighfertilitywouldbeadisadvantageundernaturalconditionsbecauseofthedifficultyofraisingthepuppies,butinahumansociety,wherethepuppiesarepartiallyraisedbyhumanbeings,itisactuallymoreefficienttorearalargelitterthanasmallone,sincetheamountofworkrequiredisroughlythesame.

Reductionofwildness.—Ifawolfpuppyistakenfromitsparentsbeforeitseyesareopenandisadoptedintoahumansociety,itwilldevelopverymuchlikeadomesticdog.However,adoptionbecomesrapidlymoredifficultasthe

likeadomesticdog.However,adoptionbecomesrapidlymoredifficultasthewolfcubsgrowolder,becauseofthequickdevelopmentoffearreactionsandfightingbehavior.Anolderwolfcubbitesinfranticfearwhencaught.AlthoughGinsburg's(1963)recentworkhasshownthatevenadultwildwolvescanbesocializedeventually,thisisalonganddelicateprocess.Therehasevidentlybeenselectionindogstowardtheextensionofthecriticalperiodduringwhichsocializationiseasy.Theremayalsohavebeensomereductionofalertnessandwarinessofstrangesoundsandmovements,butthisisdoubtful,becauseoneoftheprincipalvaluesofdogsisjustthiscapacity—toalertthehouseholdertopossibledangers.Infact,aperennialprobleminmostbreedsisthedevelopmentofmoretimiditythanthebreedersconsiderdesirable.

Thespecializationofbehavior.—Inalmostanybehavioralcharacteristictherearebreedsofdogswhichsurpassthecapacitiesofwolvesineitherdirection.Theterrierbreeds,asevidencedbytheirincapacityforlivinginlargegroups,aremoreaggressivethanwolves,whereasthehoundbreedslikethebeaglesarefarlessaggressive.Greyhoundsarefasterrunnersthanwolves,butmanydogsarcmuchslower,especiallythosefromshort-leggedbreedssuchasthedachshund.Somebreedslikethetrailhoundsappearto

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bebettertrackersthanwolves,whereasothersliketheterriersappeartobepoorer.Thesheepdogsarebetterherdersthanwolvesand,ofcourse,manybreedsaremuchpoorer.Thesetters,pointers,spaniels,andotherbirddogsappeartohavemuchmoreinterestinbirdsthandowolves,aspecialcapacityusefulonlywithhumanco-operation.Wolvesthemselvesarepoorbirdhunterscomparedtofoxes.

Althoughmanvbreedsofdogsconsistentlyexceedwolvesintheircapacities,noneofthemcanbeconsideredsuper-wolves.Theirspecialcapacitieshavebeenachievedatthepriceofsacrificingothers.Thegreyhoundhasachievedspeedbysacrificingtheheavymusclesandjawswhichenableawolftoliveonbonesifneedbe.Itisinconceivablethatanyparticulardomesticbreedcouldcompetewithwolvesundernaturalconditions,withthepossibleexceptionoftheEskimodogs.Eventhesewouldbeatadisadvantagebecauseoftheirsmallerteethandjaws.Infact,dogshavesuccessfullygonewildagainonlywherethereisanabsenceofsuchcompetition,asonthecontinentofAustraliaoraroundtownsandcities.

Noneofthedogbreedsaresuper-wolves.Awolfisaruggedandpowerful

Noneofthedogbreedsaresuper-wolves.Awolfisaruggedandpowerfulanimaladaptedtolifeunderavarietyofadverseconditions.Consequently,nooneofhisbehavioralcapacitiescanbedevelopedtoahighdegree.Comparedwithwolves,dogsareagroupofspecialists.Butastheyareco-ordinatedandshelteredbyhumansocietytheycanperformtheirfunctionsmoreefficientlythananygroupofwolves.

Wecanconcludethatthedevelopmentofall-roundcapacitiestomeetavarietyofenvironmentalconditionsleadsnottoasuperbdevelopmentofthesecapacitiesbuttoabalancebetweenthem.Anall-rounddevelopmentmeansgreatadaptability,butnotsuperbperformance.

Thissuggeststhattheideathatnaturalselectionwillproduceasuper-manorsuper-animalofanysortisanunobtainablemyth.AsfarbackastheGreeks,andpossiblylongbefore,peoplehavedreamedofgodlikeorheroicfigureswhocombinedthephysicalstrengthofagorillawiththeintelligenceofanEinstein,themusicalgiftsofaBeethovenwiththebeautyofaGreekGod.Fromthehistoricalandgeneticevidenceaffordedbydogs,thisappearstobeanimpossibility,andwearenowbeginningtorealizewhy.Ontheotherhand,acomplexsocietycanuseallthesesuperbqualitiesintheformofspecializedindividuals,sothatthesocietyasawholehascapacitiesfarbeyondthoseenjoyedbyauniformlydevelopedgroup.Thesuper-manisnottobefoundasanindividualbutasawell-developedhumansociety.

THEACCUMULATIONOFMUTATIONS

AlmostassoonasDarwinputforwardhistheoryofnaturalselection,scientistsbegantoreasonthatifnaturalselectionwouldcausetheimprovementofaspecies,thentherelaxationofselectionwouldautomaticallycausedegeneration.Theargumentseemedplausibleenoughbecause,ifunfitindividualswerenoteliminated,thereoughttobemoreoftheminthenextgeneration,andifthisprocesscontinuedgenerationaftergeneration,theresultwouldeventuallybegeneticdisaster.However,thisideafirstbecamecurrentbeforethediscoveryofMendeliangeneticsandlongbeforewehadanyideaoftheprocessofmutation.Asweshallseebelow,therelaxationofnaturalselectiondoesnotnecessarilyleadtodegeneration.

TheHardy-Weinberglaw.—OncethemechanismofMendelianheredityhadbeendiscovered,itwaspossibletomathematicallycalculateitseffectuponfuturegenerations.Allchromosomesexistinpairs,andthereisanequalprobabilitythatoneortheotherofeachpairwillbepassedalongtoan

probabilitythatoneortheotherofeachpairwillbepassedalongtoanindividualinthenextgeneration.Inaninfinitelylargepopulationwithnoselectionandnoassortivemating,genescarriedonthesechromosomeswillthereforebepassedalonginexactlythesameproportionasthatexistingintheparentpopulation.TheMendelianmechanismhasthefunctionofrecom-biningthesegenesinallpossiblecombinationswithoutchangingtheirfrequency.Thisprinciple,knownastheHardy-WeinbergLaw,maybebrieflystatedasthatof"theconstancyofgenefrequency."

Therefore,thereisnothingintheordinarymechanismofinheritancetocausedegeneration.Ifnaturalselectionceasestoactuponalargepopulation,thehereditypresentinthegroupatthistimewillbepassedalongwithoutchangefromonegenerationtothenext,fromthattimeforward.Theresultisneitherdegenerationnorimprovement,butstability.

Thesituationisslightlydifferentinasmallpopulation.Heretheaccidentalselectionofonekindofparentsmayproduceashiftinheredityfromonegenerationtothenext,butthechangeisaslikelytobeinthedirectionofimprovementastowarddegeneration.InaLargepopulationcomposedofanumberofsmallsubgroups,wewouldexpectthatsomewouldbeimprovedandsomeworsened,willithewholepopulationremainingexactlyasbefore.

ThusneithertherelaxationofnaturalselectionnortheoperationoftheMendelianmechanismofhereditywillleadtoprogressive

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geneticdeterioration.Theoneremainingpossibilityofdegenerationliesintheprocessofmutation.

Theeffectofmutationonthedog.—Thedogprovidesanextremeexampleoftheunfavorableeffectsofmutation.Notonlyhasselectionbeenrelaxedbecausedogownersprotectandfeedtheirpetsfromthekenneltothegrave,butfanciershavepracticedbreedingsystemswhichactuallyincreaseandmultiplyinjuriousmutations.Inthefirstplace,theyhaveselectedcertainfreakishtraits,suchasthebulldoghead,whicharedefinitelyinferiortothenaturalconformation.Second,theyhaveselectedforneutraltraitssuchascoatcolorwithoutregardtoviabilityandfertility.Thebestlookingshowanimalinalittermayaccidentallybeapoorbreederorsubjecttovarioussortsofsickness.Third,inrecenttimesmostdogbreedershavedeliberatelyfollowedapolicyofoutbreeding,tryingvarioussorts

breedershavedeliberatelyfollowedapolicyofoutbreeding,tryingvarioussortsofmatingsbetweennon-relateddogsinthehopeofobtaininganunusualordesirabletype.Forpracticalpurposesthisisagoodwaytochangeorimproveabreed.However,continuousoutbreedingalsotakesawaythenaturalmethodofreducingthenumberofinjuriousrecessivegenes,i.e.,throughdeathorinfertilityofhomozygousindividuals.Underthesebreedingmethodssuchrecessivegeneswillnotevenberecognizedunlesstheybecomesofrequentinthepopulationthatcarriersbegintomatewitheachother.AccordingtotheHardy-WeinbergLaw,thereshouldbenospreadofsuchmutationsthroughthepopulation,butthedogbreedershaveprovidedamethodfordoingjustthis.Ifamalebecomesagreatchampion,everyonewantsoneofhispuppies,andhemaybebredtoseveralhundredfemales.Ifhecarriesevenonerecessivegene,itwillbespreadthroughoutthewholebreedinsuchnumbersthatitwillbealmostimpossibletoeliminatewhenhisdescendantseventuallybegintobematedwitheachotheranditisfinallyrecognizedasaseriousproblem.Thuscurrentdogbreedingpracticescanbedescribedasanidealsystemforthespreadandpreservationofinjuriousrecessivegenes.

TheseriousnessofthiseffectiswellillustratedinTable16.1.Inthepurebreeds,theneonataldeathrateaveragesabout15percent.Thisis,ifanything,anunderestimateofmortalityratesinthetotalbreedpopulations,sincefemaleswithunusuallygoodbreedingrecordswereselectedforourexperimentwheneverpossible.TheFihybridsshowedonlytwoneonataldeaths,bothstillbirths,andthemortalityrateinthesegregatinghybridsisintermediatebetweentheFi'sandthepurebreeds.AssumingthattheFideathswerecausedby

GENERALIMPLICATIONS

TABLE16.1MortalityRateper100BirthsenPureBreedsandHybrids

Excludingfiveanimalswhichdiedindistemperepidemic.

environmentalaccidents,wecanestimatethatthegeneticdeathrateis10to12percent.Estimatesfromothercoloniesgiveneonataldeathratesofanywherefrom10to30percent(Corbinetah,1962),dependinguponthestrainofanimalsinvolved,sothat15percentshouldbeagoodroughestimateofneonatalgeneticmortalityforpurebreedsingeneral.

Inadditiontotheselethaleffects,thereiswidespreadoccurrenceofcripplingdefectsanddeformitiesinpurebreddogs.Inourexperimentswebeganwith

defectsanddeformitiesinpurebreddogs.Inourexperimentswebeganwithwhatwereconsideredgoodbreedingstocks,withafairnumberofchampionsintheirancestry.Whenwebredtheseanimalstotheircloserelativesforevenoneortwogenerations,weuncoveredseriousdefectsineverybreed.Asmentionedinthelastchapter,ourAfricanbasenjisshowedahighfrequencyofundershotjawsinbothsexesandofinguinalherniainthemales.Beaglesshowedanoppositedefect—areductionofthelowerjaw.Untilcorrectedbvselection,wire-hairedfoxterriersproducedmanypuppieswithclubfeet.TheShetlandsheep-dogsproducedindividualswithhereditaryobesity.Allbreedsshowedatendencytodeclineinfertility.'

Inaddition,thecockerspanielsshowedanoutstandingdefectwhichhadapparentlybeenestablishedthroughoutthestrainbeforewereceivedit.Thisbreedhasbeenselectedforabroadforeheadwithprominenteyesandapronounced"stop,"oranglebetweenthenoseandforehead.Whenweexaminedthebrainsofsomeoftheseanimalsduringautopsy,wefoundthattheyshowedamilddegreeofhydrocephaly;thatis,inselectingforskullshape,thebreedershad

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accidentallyselectedforabraindefectinsomeindividuals.Besidesallthis,inmostofourstrainsonlyabout50percentofthefemaleswerecapableofrearingnormal,healthylitters,evenundernearlyidealconditionsofcare.

Amongotherdogbreeds,suchdefectsarequitecommon.Onewhichhasrecentlyreceivedagreatdealofattentionishipdysplasia,particularlyinGermanshepherds,butalsofairlycommonlyinotherbreeds.Inthisdefectthehipjointisnotproperlydeveloped,withtheresultthattheanimalsbecomelameandcrippled.IntheGermanshepherdbreeditisassociatedwiththefactthattheshowbreedershavepreferredasortof"downhill"carriage(associatedwith"angulation"ofthehindlegs)inwhichtheshouldersarehigherthanthehips.Inselectingforthistraittheymayhaveunwittinglyselectedforlamedogs.

Anotherexampleishereditarvhemophilia,whichhasbeendiscoveredinEnglishsetters.Indeed,almostanyimportantconstitutionaldiseaseofhumanbeingshasitscounterpartindogs,whichareconsequentlyhighlyusefulformedicalstudy.Alltheevidenceisinfavoroftheconclusionthatinjuriousrecessivemutationshaveaccumulatedinthedogandbecomeextremelvcommon.Atthesametimethereisnoindicationthatdogsarebecomingextinctasaresultofgeneticdeterioration.Ifanything,therearemoredogstodaythaneverbefore.

deterioration.Ifanything,therearemoredogstodaythaneverbefore.

Thetheoryofgeneticequilibrium.—Thehereditarycompositionofanywildspeciestendstoreachaconditionofbalance,insofarasthevariousfactorsproducinggeneticchangeworkagainsteachother.Forexample,theincreaseofinjuriousrecessivemutationsreachesastateofbalancewiththedeathrateofhomozygousindividuals,andthefrequencyofappearanceofhomozygotesdependsuponthedegreeofinbreedinginthepopulationaswellasonthemutationrate.

Inthecaseofthedomesticdogasimilarbalanceseemstohavebeenreached.Onereasonwhydogsarenotdisappearingisthat,althoughabout50percentofthefemalesareunabletoproducelivingyoung,reproductionbyafertileanimalisapproximatelydoublethatoftheancestralwolves.Thecaninereproductiveratefarexceedsthatforhumanbeings,asagoodbitchmayeasilyproduce50livingoffspringbythetimesheis6yearsold.Thisincreasedreproductivecapacitymorethancompensatesforthegeneticlossoffertility.

Inspiteoftheaccumulationofrecessivemutations,thereisstillselectionagainstabnormalindividuals.Extremelydefectiveindi-

victuals,suchasdogswithhereditaryobesity,areoftencompletelyinfertile.Thosewithminordefectssuchasundershotjawarefrequentlynotchosenforbreedingstock,anddogbreedersarebecomingmoreandmoreawareofthenecessityofselectingforgoodhealthandvitalityaswellasparticularshowpoints.Inshort,eveninahighlyprotectedspecies,naturalselectionisnotcompletelyinoperable,nordoesartificialselectionalwaysworkagainstit.

Wecouldmakeanotherpointinpassing.Adogwhichisinfertileorunsuitableforbreedingmaystillmakeahighlysatisfactoryhousepetorevenoccasionallybeanoutstandinglysuccessfulperformerasaguidedog,hunter,orherder.Inasocialanimal,orananimalsuchasthedogwhichisactuallypartofhumansociety,reproductivityisnotthesolecriterionofusefulness.

Wecanconcludethattherelaxationofnaturalselectioninthedoghasnotproducedacontinuingprocessofdegenerationbutratherhassetupanewconditionofgeneticbalancewhichpermitsawiderdegreeofvariation.

Thetheoreticaldangerfrommutations.—Fromthestudyoffruitfliesandmice,geneticistshavebeenabletocalculatemutationrates.Somegenesmutatefairlyfrequentlyandothersalmostnever.Theaveragerateseemstobeaboutone

frequentlyandothersalmostnever.Theaveragerateseemstobeaboutonemutationinaparticulargeneforeverymillionindividuals.Mutationscanalsobeinthereversedirection;anewmutationwilloccasionallyreverttotheoriginal.Theaveragerateispresumablythesameineitherdirection,andwecanhypothesizethatifamutationhadnoeffectonsurvivalandwasthereforenotremovedbynaturalselection,theprocessofmutationwouldgoonuntilthereversemutationratebalancedtheoriginalrate,whichshouldbeatthepointwheretherewouldbeequalnumbersofthenewmutationandtheoriginalgene(Wright,1955).

Thiskindofmutationmaybeverycommon,butusuallyescapesnoticebecauseamutationwhichhaslittleeffectonsurvivalis,ofcourse,onewhichhaslittleeffectofanykind.Themutationswhichwenoticearethosewhichproducelargeeffects,andthesearealmostuniversallyinjurious.Ifsuchaninjuriousgeneshouldoccurinashigharatioasinthehypotheticalexampleabove,inwhich50percentofthegenesinthepopulationwereofthemutantsort,therewouldbe25percentofdefectiveindividualsineverygeneration.Ifthesedefectiveindividualswereascapableofreproductionasnormalanimals,thesamehighproportionofdefectiveswouldbemaintainedinfuturegenerations.Theconsequencewouldbeacontinuingheavyburdenonthepopulation.

However,allourevidenceindicatesthatdefectiveindividuals,

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whiletheymayoccasionallybeabletoreproduce,arealwaysselectedagainstandfrequentlyarecompletelyinfertile.Ifthewhole25percentofdefectiveindividualsinapopulationwereincapableofreproductioninthenextgeneration,one-halfofthenormalgeneswouldhavetomutateineachgenerationinordertomaintainanequalratioofmutantandnon-mutantgenes.Thisisatremendouslyhighmutationratecomparedwithoneinamillionor,indeed,withanythingthathasbeenproducedartificiallybyradiation.

Manyscientistsareconcernedwiththegeneticeffectsuponhumanpopulationsofincreasedexposuretoradiation,eitherinmedicalpracticeorthroughtheuseofatomicweapons,orevenbyexposuretoradiationinouterspace.AccordingtoCrow(1961),anyincreaseinthemutationrateoverthenaturaloneisabadthing,asitwillinthelongrunincreasethenumberofseriouslydefectiveindividualsinourpopulation.Togivesomeideaofwhatthisincreasemightmean,Morton(1960)hascalculatedtheeffectofdoublingthemutationrateforcertaindefects,untilaconditionofequilibriumisreached.Themutationratecan

certaindefects,untilaconditionofequilibriumisreached.Themutationratecanbedoubledwiththesurprisinglylowradiationdoseof25roentgenspergeneration.Whenanirradiatedpopulationofonemillionpeoplehadreachedstability,therewouldbeanincreaseofatleast60casesoflimb-girdlemusculardystrophy(adiseaseinwhichthemuscleswasteaway),450casesofdeafmutism,and1,370casesoflow-gradementaldeficiency—anincreaseofsome1,880defectiveindividualsinjustthesethreecategories.

Anincreasedmutationratewould,ofcourse,greatlyincreasetheprenatalandpostnataldeathratesofhumaninfants.Wearestillagreatdealbetteroffthanpurebreddogs.In1960thecombineddeathsatbirthanduptooneyearofagewerelessthanoneineverytwentylivebirths,whilethecorrespondingfiguresinpurebreddogswereaboutoneinfive(Table16.1).Withincreasedmutationrates,wecouldexpecttheneonatalandinfantiledeathratestorisetoamuchhigherlevelthanatpresent.

Wehavebeenthinkingofthedogasbeingapilotexperimentforthegeneticfutureofthehumanrace.However,humanheredityneednotfollowthesamecourse,becausewecanatleastavoidthemistakeofspecialselectionofdefectiveindividualsforparents.Theexampleofthedogissomewhathopeful,inspiteofalltheunfavorablechangesthathavetakenplace,becausethespeciescontinuestoflourish.Byanalogy,wemaypredictthathumanhereditywilleventuallycomeintoanewconditionofbalance,dependingonthenatureoftheforcesforchange.

Withregardtofertility,oneofourmostimportantworldprob-

lemsisthatofincreasedhumanfertilityproducedbysuperiornutritionandmedicalcare.Thereisnoindicationthattherehasbeenanygeneticincreaseinfertility,asinthedog.Ontheotherhand,weknowthatatthepresenttimeabout10percentofmarriagesintheUnitedStatesareconfrontedwiththeproblemofsterility.Wemayexpectthatifmutationratesincrease,thepercentageofsterilitywillgraduallyriseandwillintimereachabalancewhichwouldcancelouttheincreasedsurvivalrate.However,itmighttakecenturiesbeforesuchbalanceisactuallyachieved.

Thechangesproducedbyincreasedmutatationratesmustbeslow,forevenifnaturalselectionisrelaxedinanypopulation,itiscertainlynoteliminatedandmayevenbeincreasedinsomerespectsthroughthespecialstressesofcivilizedliving(Dobzhansky,1962).Thereisalwaysselectionagainststerility.Morethanthis,theimprovementoftheenvironmentachievedbysocialandcivilizedliving

this,theimprovementoftheenvironmentachievedbysocialandcivilizedlivinghasmadeverylittlechangeintheprenatalenvironment.Theusualestimatesindicatethatthereisaprenatalmortalityrateofapproximately20percent,thatoneoutoffivepregnanciesnevercomestoterm.Therealratemaybeevenhigher,sincemanyembryosdiesosoonthattheirexistenceisordinarilyneverdetected.Figuresforsomeofthedomesticanimalsindicateaprenatalmortalityrateof30to40percent.Prenatallifeisthereforethemajorscreeninggroundforinjuriousmutationsandonewhichisnotlikelytobeseriouslyinterferedwithinthefuture.Theprenataldeathratealsoindicatesthatthereareactuallyalargenumberofinjuriousmutationsalreadypresentinhumanpopulations(Mortonestimates3to5perindividual),andthatthereisstrongselectionagainstthem.

Togetthewholematterintoperspective,therelaxationofselectionchieflyaffectspostnatallife,afterthemostimportantpartofselectionhasalreadytakenplace.Eveninpostnatallife,naturalselectionhasnotbeeneliminated.Parentswhohaveadefectivechilddonotrecklesslyhavemanymore,beingstronglydeterredbytheinevitabletragedyandexpense.Itusedtobethoughtthatwewereselectinginfavoroffeeblemindedindividuals,andthatmoronswouldbreedlikerabbits.AsReed(1963)hasshown,theactualfiguresindicatethatwhiletheremaybeafewexceptionalfeeblemindedpersonswithmanychildren,theaveragefeeblemindedindividualhasfarfewerchildrenthantherestofthepopulation.Furthermore,thenearrelativesofsuchpersonsalsohavefewerchildren.

Inshort,wemayconcludethattherelaxationofnaturalselectioninhumansocietiesliasnotsetintomotionacontinuingprocessof

degenerationbuthasrathersetupanewconditionofequilibriumwhichpermitsawiderdegreeofvariation.Inaddition,weshouldrememberthatsomeofthesevariantsmaywellhavespecialabilitiessuperiortotheidealofanall-roundman,insteadofbeinginvariablybelowtheaverage.

Wehavealreadyshownthatselectivebreedinghasnotproducedasuper-wolfamongdogs,andwemightpredictthatifanyoneshouldattempttoselectabreedofmenhavingall-roundability,health,andvigor,hewouldprobablyproducenotagroupofsupermen,butaveryaveragegroupofindividualswithnoexceptionalqualities.Inessence,suchpeoplemightindeedbeverysimilartoStoneAgemen,butwehavenoindicationthatprimitivemenwereanythingotherthanextremelytoughindividualswhocouldsurviveundermanyconditions.Bycontrast,ourpresentsituationwithitsrelaxationofselection

conditions.Bycontrast,ourpresentsituationwithitsrelaxationofselectionpermitsthetryingoutofalmostinfinitenumbersofgenecombinations,andsomemodernindividualsmaywellbesuperiorinall-aroundabilitiestothebestthatStoneAgemancouldoffer.However,underourpresentcircumstancesoflargepopulationsandpanmixis,thesegenerallysuperiorindividualsareunlikelytoproduceanewraceofmen.Iftheyappear,theywillmakeasocialratherthanageneticcontributiontothefuture.Eveninthisrespect,theirsocialvalueislikelytoberelativelysmallcomparedtothatofindividualswithmarkedlysuperiorspecialtalents.

Presentconditionspermitthesurvivalofsociallyvaluablebutgeneticallyspecializedindividuals,lackingtheall-roundsurvivalcapacitiesofStoneAgeman,butpossessingextremelysuperiorspecialqualitieswhichcanbeusedtogoodadvantageinahighlydevelopedcivilizedsociety.

Humansocietyisthusbasicallypolymorphic(Dobzhansky,1962).Aswithothersocietiesofmammals,wearebiologicallydifferentiatedintothreetypes:males,females,andyoung.Ahighdegreeofsocialorganizationencouragesthedevelopmentofafurtherdiversityofindividualswithinthesemainclasses.Eveninasocietyofwolves,itisanadvantagetohavebothextremelytimidandextremelycourageousanimals.Thetimidanimalmayscentdangerfromafarandwithdrawtowarntheothers,whiletheboldanimalmaypressforwardtoinvestigateandobtainfoodforthepackwhenthedangerprovestobesmall.Inahumansocietyadiversityofindividualsisevenmoreuseful.

Ahumansocietythusrestsonageneticbasisdifferentbothfromthatintheinsects,wherepolymorphismisexpressedinasmallnumberofgeneticallydeterminedcastes,andfromthatindogs,where

412GENERALIMPLICATIONS

geneticdiversityisorganizedintobreeds.Humansocietiesarefoundedonthegeneticbasisofmanyindividualdifferenceswithinthethreebiologicaltypesofmales,females,andyoung,andtheidealhumansocietyisconsequentlyonewhichrecognizes,respects,anduseshumanindividualityandvariation.

CHAPTER17

TOWARDASCIENCEOFSOCIALGENETICS

Thescienceofheredityisprimarilyconcernedwiththeactionofgenesorbasichereditaryunits.Atfirst,theprincipalproblemwastheirtransmissionfrom

hereditaryunits.Atfirst,theprincipalproblemwastheirtransmissionfromgenerationtogenerationbymeansofthechromosomes.Later,scientistsbecameinterestedinhowgeneswork,andthisproblemdevelopedintoasubscienceofphysiologicalgenetics.Anotherproblemwashowgenesaredistributedandpassedalonginnaturalpopulations,asopposedtothecontrolledexperimentsofthelaboratory.Inanswertothisquestionthesubscienceofpopulationgeneticswasborn.

Thescienceofheredityhasthusbeensubdividedaccordingtoitseffectsatdifferentlevelsofbiologicalorganization.Inordertocompletethetable,weneedtoaddtwomoredivisionsattheindividualandsociallevels.Oneconcernstheeffectofgenesontheactivityofanentireindividual.Thisdivision,whichwecall"behaviorgenetics,"istreatedinchapters7-14ofthisbook.Anotherinvolvestheeffectofgeneticsonsocialgroups,or"socialgenetics."Finally,thescienceofdevelopmentalgeneticscutsacrossalllevelsoforganization(Table17.1).

TABLE17.1TheSubdivisionsofGenetics

LevelofOrganization

Ecological

Societal

BehavioralorPsychological

Physiological

Cellular

Molecular

UnitofOrganization

Subdivision

Population

Society

Organism

Organs,tissues,etc.

Cells

Gene

PopulationgeneticsSocialgeneticsBehaviorgeneticsPhysiologicalgeneticsMendeliangeneticsChemicalgenetics

oa

GENERALIMPLICATIONS

Forthemostpartpopulationgeneticshasdealtwithtwounits:theindividualandthewholepopulation.Researchworkerssometimesassumefortheoreticalpurposesthatapopulationisunorganized,withitsmembersmovingaboutandmatingatrandom,justasagroupofgasmoleculesareunorganized.Thisassumptionmaybejustifiedinmanycases,particularlyinsomeoftheloweranimals,butthehigheranimalsarealwaysorganizedintosomesortofsocialgroupsinwhichtheyneithermovenormatecompletelyatrandom.Furthermore,insuchsocialanimalsthereisanewbasicunit,thesocialrelationship,whichmeansthattwoormoreindividualsformaunit.Anumberofrelationshipsinturnmakeupanorganizedgroup,whichmayrangeinsizefromasinglepairtoseveralhundredindividuals.Inmanyanimalseachgroupconstitutesanentiresocietyinitself,butinmanyothersthegroupshaveatleastsomeconnectionwitheachotherandareorganizedintoalargerwhole.Amonghumanbeings,suchgroupsofgroupsaremorecomplexlyorganizedandmakeupinstitutions,anditisagroupofinstitutionsthatbecomesasociety.Finally,apopulationmayconsistofasinglesocietyoragroupofsocieties,dependingonthesizeofthegeographicalunitonwhichitisbased.

Thesedifferencesbetweenvariouskindsofsocietiesmeanthatthefirstproblemofsocialgeneticsisoneofbasicinformation.Weneedtoknowtheanatomyoftheanimalsocietywithwhichwedeal:thecompositionofgroups,thenatureoftherelationshipswithinagroup,andtheimportanttypesofbasicrelationships.Withinthisframework,therearetwomajortheoreticalproblems.Oneishowgeneticsaffectsarelationshipandtheotheristhereciprocalquestionofhowthesocialenvironmentaffectsgeneticsandtheprocessofevolution.

THEANATOMYOFCANINESOCIETIES

AllmembersofthefamilyCanidaeshowthesamebasicpatternsofsocialbehavior,justastheyshowthesamebasictypeofstructure(Scott,1950).Evenfoxes(Tembrock,1957)gothroughmuchthesamepatternsofsexualandagonisticbehaviorasdogsandwolves.Suchdifferencesasexistarechieflymattersofdegreeratherthankind.Afox'sbarkcaneasilybetoldfromthatofadog,butitisstillrecognizablyabark.

Theprincipaldifferencesbetweenthesecaninesocieties,there-loir,lienotinbasicsocialbehaviorpatterns,butindiecomplexityofsocialgroups.Forfoxes,thematedpairisthelargestsocialgroupasidefromthetemporaryassociationofamotherandheryoung

SOCIALGENETICS415

litter,andfoxbreedershavegreatdifficultyingettingmalestomatewithmorethanonefemale.Likewise,thematedpairisthetypicalgroupincoyotesandjackals,althoughtheyareoccasionallyseeninsmallpacks.Attheoppositeextremearethedogsandwolves,whosetypicalorganizationisthepackofseveraladultmalesandfemales.Inwolves,agroupcomposedofasinglematedpairistheexceptionratherthantherule.

Thecomparativebehaviorofcanineindividualssuggeststhatbehaviorisaconservativetraitinevolutionjustastheircomparativeanatomysuggeststhatgeneralbodyformisresistanttochange.Inspiteofallthehumanselectiontowhichdogshavebeensubjected,westilldonothaveanytwo-leggedbreedsofdogsordogsthatemployhumanspeech.Conservatisminbothformandbehaviorprobablyresultsfromthefactthatitisdifficulttochangeanyhighlyorganizedsystemwithoutdisruptingit.

Incontrasttotheanatomyandbehaviorofindividuals,thestructureandfunctionofcaninesocietiesisrelativelylabileandchangeable,therebeingwidedifferencesinthecompositionofgroups.Thebasicreasonforthisliesinthetransitionfromoneleveloforganizationtoanother.Therearegreaterchangesonthesocialleveloforganizationthanonthebehaviorallevelbecauseanewtypeoforganizationonthehigherlevelcanbeconstructedwithoutgreatlymodifyingthatonthelower.ThebehaviorpatternsofwolvesaredifferentfromotherCanidaeinonlyminorways,butthesemakepossiblethedevelopmentoflargersocialgroupsandallthatalargegroupcandoincontrasttoasmallone.

largersocialgroupsandallthatalargegroupcandoincontrasttoasmallone.

Thetypicaldogorwolfsocietyisnotahighlyorganizedone.Thenumberofindividualsinapackisusuallysmall,andtherelationshipsbetweenthemembersaresimple.Foodisdividedthroughadominanceorganizationbutcanbeobtainedeitherbycombinedorindividualeffort.Asmightbeexpectedinagroupofanimalswhicharelikelytobeallthesameage,thereisnostrongsystemofleadership.

Whensocializedtopeople,bothdogsandwolvestransfertohumanbeingsthesocialrelationshipswhichtheywouldnormallydevelopwiththeirownkindinsofarasthisispermittedbytheirowners.Dogsdonotacquirehumanbehaviorthroughthisassociation,butcontinuetoshowthedog-likepatternsofbehaviorcommontoalltheCanidae.

Noveltydoesariseinthedevelopmentoftherelationshipbetweendogandhuman.Peopletransfertheirsocialrelationshipstodogsandattempttoteachthemhumansocialcustomsandnewskills.The

resultisarelationshipwhichisneithertypicallyhumannortypicallycanine.Thedogisnolongeranequalmemberofapack,althoughhewilldevelopalongtheselinesifallowed.Ratherhebecomesaperpetualfolloweranddependent.Norishelikeahumanchild,whoeventuallybecomesmoreindependentandcapableofcaringforothersofhiskind.Thedogbringsbonesbacktohisyardashewouldtoapack,butthesearenotsharedbyhismaster.

Inourexperimentswehaveprincipallystudiedtheeffectofgeneticsuponthesetwosimplesocialrelationships:thatbetweenthepuppyandhislittermatesandthatbetweendogandmaster.Thesimplicityoftheserelationshipshasmadethetasksomewhateasierthanitmightotherwisehavebeenandalsohashadtheadvantageofmakingcertaingeneralprinciplesmoreobvious.

Thedevelopmentanddifferentiationofsocialrelationships.—Oneofourmostimportantdiscoverieswasthatthedevelopmentofpuppiesisdividedintodefiniteperiods,eachcharacterizedbyanimportantprocess.Theneonatalperiodisdominatedbytheprocessofinfantilenutrition.Thetransitionperiodisoneofrapidacquisitionanddevelopmentofadultbehaviorpatterns.Theperiodofsocializationisoneofdevelopmentofprimarysocialrelationships.Thejuvenileperiodisoneofgrowthandtheacquisitionofskillswhicheventuallymakethepuppypotentiallyindependentofitsparentsorcaretakers.Finally,sexualmaturitymarksthedevelopmentofsexualrelationships,andtheconsequent

maturitymarksthedevelopmentofsexualrelationships,andtheconsequentbirthofyoungmakespossiblethedevelopmentoftheparentalrelationshipwithanewgeneration.

Socialdevelopmentcorrelatedwithsocialorganization.—Caninedevelopmentissoorganizedthattheperiodofsocializationisoneinwhichthemothernormallyleavespuppiesforlongperiodswhilethelitterstaystogetherandwaitstobefed.Consequently,thestrongestsocialrelationshipsareformednotwitholderanimalsbutwithlittermates,andthisappearstobethefoundationforpackformation.YVestilldonothavecompleteinformationonthenaturalformationofnewpacksinwolves,butMurie(1944)observedayounglittermovingaboutasaunitasitgrewup,alreadyactingasapack.Healsosawasingleadultattemptingtojoinanestablishedpackandbeingrejectedbyit.Itseemslikelythatmostwolfpacksareformedbylitterswhichstaytogetherasadults.

Thusthedevelopmentofsocialbehaviorindogsisdirectlyrelatedtothetypeofsocialorganizationtypicalofadultwolvesanddogsallowedtorunwildinpacks.Whenwecomparecaninedevelopmentwiththatinotherspecies,wecansecthatwehavegoodevidenceofagenerallaw.Insheep(Scott,1960and1962a),theyoungareborn

SOCIALGENETICS417

capableofmovingaroundactively;theprocessofsocializationbeginsimmediatelvafterbirth:andlambsbegintofollowtheirmotherswithinafewdavs.Thusthestageissetfortheformationofpermanentflocksledbvolderanimalsincontrasttothecaninepackofasimilaragegroup.

Humanbeings,thoughdifferentfromeithersheepordogs,followthesamegenerallaw.Thevaremorelikedogsinthatbabiesareborninanextremelyimmaturestate,butunliketheminthatphysicaldevelopmentismuchslower.Alongwiththis,theprocessofprimarysocializationbeginsbeforethetransitiontotheadultformoflocomotion,atatimewhentheinfantsstillrequireconstantcare.(Scott,1963a).Thismeansthatbabiesformtheirprimarysocialrelationshipswitholderpersons.Humansocieties,andindeedmostprimatesocieties,arecharacterizedbvlongassociationsbetweenyoungerandoldermembersofthegroupandinthiswayaremorelikeasheepsocietythanacanineonewherethemembersofapackmayallbethesameage.However,humanbeingsaresharplvdifferentfromsheepbecauseoftheirslowdevelopment,whichmeansthatthehumaninfantishelplessandmustbecarriedwhiletheprocessofsocializationisgoingon,whereasalambisimmediatelycapableof

processofsocializationisgoingon,whereasalambisimmediatelycapableofindependentlocomotionandatoncestartstoformahabitoffollowingitsmother.Theoreticallvthiswouldmakethehumaninfantdevelopsomewhatmoreindependently,sincetraininginfollowingbeginsrelativelvmuchlaterinlife.

Ifthisgeneralizationiscorrect—thatthedevelopmentofsocialbehaviorisdirectlyrelatedtothetypeofsocialorganizationtvpicalofadults—itshouldfollowthatthedisturbanceofsocialdevelopmentwouldcausethedisturbance(oratleastthemodification)ofsocialorganization.Thepointatwhichthemaximumchangeinsocialdevelopmentcanbemosteasilyproducedisduringtheprocessofsocialization.Thisisthereforeacriticalperiodforthedeterminationofadultbehaviorandsocialorganization.

Ourevidenceonthepuppyreinforcesthegeneralconclusionthatinanyhighlysocialspeciesofanimalthereisarelativelybriefperiod,usuallyearlyindevelopment,whenprimarysocialrelationsareestablished,normallytomembersofthesamespecies.Duringthisperiod,itiseasytotransfersocialrelationshipstoanotherspeciesbyexperimentalmeans.Thislawhasgreatsignificanceinexplainingthedomesticationandtamingofwildanimals.Italsohasmanyimplicationsforthemodificationofsocialorganizationinhumanbeingsandthedisruptionoforganizationbydisturbancesindevelopment.


Geneticvariationindevelopment.—Now,howdoesgeneticsmodifythesegeneraldevelopmentalprocesses?Inthefirstplace,alldogbreedsgothroughthesamesequenceofdevelopmentalstagesandprocessesatapproximatelythesametime.Thevariationsduetoselectivebreedinghaveproducednofundamentaldisturbanceofdevelopment.However,therearevariationsinthespeedofdevelopmentofvariousbehavioralcapacities,andthesecanvaryindependentlyofeachother.Foxterriers,forexample,arequicktodevelopthecapacityforhearingbutat3weeksofageareslowerthantheotherbreedsinmostrespects.Thisperhapsforeshadowsthefuturebehavioroftheseanimals,asfoxterriersarehighlyresponsivetosound.Thereisnoindicationthatsuchincompatibilityofdevelopmentproducesabnormality.Instudiesofhumandevelopmentithasbeensuggestedthatanindividualwhohasslowphysicaldevelopmentbutrapidsocialdevelopment,orviceversa,maybemaladjusted.Ourworkwithdogssuggeststhatsuchvariationsmayberelatedtoindividualdifferencesbutthattheresultiseventuallyawell-integratedindividual.

Inhumandevelopment,Bayley(BayerandBayley,1959)hasshownthatvariationsinspeedofdevelopmentmayhaveimportanteffectsonchildreninoursociety.Earlysexualmaturityusuallyhasfavorableeffectsonboysandunfavorableeffectsongirlsinregardtosocialadjustmenttotheirclassmates.Wehavenotobservedanyimportanteffectofthissortindogsraisedunderourconditionsexceptpossiblythelatematurationofthesheepdogs,whichperformedrelativelypoorlyonmanytests.Thegeneraltraditionamongdogownersisthattheseanimalsdevelopconfidencemoreslowlythansomeotherbreeds.However,thereareotherpossibleexplanationsoftheirpoorperformance,andwecanonlysaythatgeneticdifferencesinthespeedofdevelopmentdonotseemtoproduceimportanteffectsintheearlylifeofdogs,althoughtheymaydosolateron.Onereasonforthisisthefactthatthepossiblerangeofsuchdifferencesintheperiodofearlydevelopmentisquitesmallcomparedwiththatinlaterlife.

Heredityandsocialrelationships.—Wemaynowconsidertheeffectofhereditarydifferencesuponthedevelopmentofasocialrelationship.Thiskindofdevelopmentgoesalongwiththebehavioraldevelopmentdescribedabove,butinvolvesinadditionthebehaviorofasecondindividual.Also,whilebehavioraldevelopmentistoalargeextentdependentongrowth,thedevelopmentofasocialrelationshipmaytakeplaceveryrapidlyandatanytimeindevelopment.

Ourbestexampleofasocialrelationshipisthedominance-sub-

SOCIALGENETICS419

ordinationrelationshipbetweenlittermates.Westudiedthedevelopmentofthisrelationshipindetailundercontrolledconditionsandfoundthatwithinitthebreedsdevelopedimportantdifferencesinagonisticbehavior.Infact,oneofthebiggestGeneticmodifica-tionsofbasicdogbehaviorpatternshasbeentheselectionofcertainbreedsforaggressivenessandothersforpeacefulness.Asdescribedinanearlierchapter,oneofthemostobviouseffectswasthelimitationofgroupsizeinfoxterriers.Foxterrierpuppieswereunabletoworkoutanvkindoflivablerelationshipinlitterslargerthanthreeindividuals.

Thesituationposesaninterestingtheoreticalquestion.Presumablythemembersofeachbreedarenearlyequalinaggressiveabilities,butthenatureoffightingmakesitimpossibleforbothanimalstowinandcontinuetobeequallyaggressive.Oneresultofthissituationmightbeafighttothedeathinthehighly

aggressive.Oneresultofthissituationmightbeafighttothedeathinthehighlyaggressivebreeds,andthisisexactlywhathappensiffoxterriersarelefttothemselves.Anotherpossibilityisthatthemoreaggressivebreedswouldworkoutsystemsofcompletedominancewhilethemorepeacefulbreedswouldshowlittleornodominanceamongthemselves.

Thebreedsdidindeedshowthiskindofdifference.Foxterriersandbasenjisshowmanymoreinstancesofcompletedominancethandobeaglesandcockerspaniels,whilesheltiesareintermediate.Examiningthesituationindetail,wefindineverybreedmorecompletelydominantmalesthanfemales,butthedifferencesbetweenthesexesinthisrespectarefargreaterinthetwomostaggressivebreeds.Thatis,inaggressivebreedsthegreatmajorityofrelationshipswithcompletedominancearecaseswheremalesaredominantoverfemales.

Hereweseetheresultofahereditarydifferencewithinbreeds—thatbetweenmalesandfemales.Whenwecomparedominancebetweenmalesinonebreedwiththatinanother,thedifferencesintheamountexpressedarenotgreat.Thebigdifferenceoccursinthemale-femalerelationships:thesearemorehighlydifferentiatedinthemoreaggressivebreedthaninthemorepeacefulone.Inadominance-subordinationrelationshiptheexpressionofageneticdifferenceinaggressivebehaviordependsuponthetwoindividualsalsobeingdifferentfromeachotherwithrespecttosex.Thiswouldnotnecessarilybetrueineverysocialrelationship,butitdoesillustratethecomplexityoftheproblemofhowadifferencebetweengenesisfinallyexpressedinasocialrelationshipbetweentwounlikeanimals.

"Personality"measuredbysocialrelationships.—Humanbeingsareoftenconcernedwiththeeffectorimpressionthatoneperson

producesonanotherandspeakofhis"personality."Oneofthedescriptivetermsappliedtohumanpersonalityisthatofdominance.Whatshallwesayaboutthe"personality"ofthedogsinthisexperiment?Obviouslywecannotsaythatallfoxterriersaredominantandallbeaglessubordinate.Thismightbetrueiftheydevelopedsocialrelationshipsbetweenthetwobreeds,butwithinitsowngroupthesamefoxterriermaybedominantinonerelationshipandsubordinateinanother,andthesamethingmaybetrueofabeagle.Neithercanwesaythatonebreedisaggressiveandtheothersubmissive.Againthisdependsuponthesocialrelationshipsconcerned.Allthatwecansayisthatafoxterrierhasagreatercapacitythansomeotherbreedstodevelopaggressivenessinarelationshipwherethecapacitiesofthetwoindividualsareunequal.Thatis,thedevelopment

wherethecapacitiesofthetwoindividualsareunequal.Thatis,thedevelopmentofthecapacitydependsnotonlyuponthepossessionoflatentabilitybutonthebehavioraldevelopmentoftheotherindividualconcerned.

Thisisanewconceptofpersonalityor,moreproperlyspeaking,amoreaccuratewaytomeasureit.Whatwearebasicallyinterestedinisthecharacteristicsocialbehaviorofanindividual.Sinceitvariesfromrelationshiptorelationship,wecanonlydescribeitintermsofthemostimportantrelationshipsinanindividual'slife.ForadogintheJacksonLaboratorySchoolforDogs,themostimportantrelationshipswerethosewithhislittermates,withthehumancaretakersandexperimenters,andwithoccasionalhumanstrangers.Thesamefoxterriermightbedominantwithallhislittermates,subordinatetothecaretakers,andfearfulwithstrangers.

Amonghumanbeingswecaneasilyobservethesamekindofcontradiction.Itisarareindividualwhoappearsthesametohiswifeastohisbusinessacquaintances.Thesmallboywhoattemptstotreathisplaygroundacquaintancesinthesamewaythathemanageslifewithhisparentsisquicklydisillusioned.Wehaveallseencasesofindividualswhoproduceawonderfulimpressionuponstrangersbutwhocannotgetalongwiththeireverydayacquaintances.Allthissuggeststhattheonlyrealisticwaytogetapracticalandmeasurablepictureofpersonalityisintermsoftheimportantsocialrelationshipsofeachindividual.Mostcurrent"personalitytests"arebasedoninformationregardingamixtureofmanyrelationshipsandoftendependupontheindividual'sviewofhimselfratherthanhisefleetonothers.Eventheclinicianseesanindividualonlyinonerelationship,thatofdoctorandpatient.Somerelationshipsarehighlyspecificandothersbroadandgeneral.Sometimestheymayresembleeachotherhut,asourexperimentalevidenceshows,somecanbehighlyindependentniothers.Attheveryleastwemustkeepinmindthe

SOCIALGENETICS

421

w

(I)

Fig.17.1.—Functionaldifferentiationofformduringgrowth.Hereditary(H)andenvironmental(E)factorsbothactonphysiologicalprocesseswithintheorganism(O),andtheseprocessesbytheirownfunctionmodifyfurther

organism(O),andtheseprocessesbytheirownfunctionmodifyfurtherprocesses.

distinctionbetweenthecapacitytodeveloparelationship,whichmaydependlargelyonheredity,andtheactualrelationship,whichdependsontheheredityoftheotherindividualaswell.

Thepredictionofsocialdevelopment.—Figures17.1to17.3graphicallyrepresenttheeffectofheredityuponthedevelopmentofasocialrelationship.Thediagramsaresomewhatartificialinthattheyareinevitablymoresimplethanreality,andbecauseitisdifficulttoexpressthefactthatseveralprocessesaregoingonsimultaneously.Thearrowsareintendedtoindicateactionofoneprocess

Fig.17.2.—Thefunctionaldifferentiationofbehaviorinrelationtothephysicalenvironment.Theorganismpreviouslydifferentiatedbygrowthprocessesat(1)isnowcapableofbehavior(B),whichmaychangethenatureoftheenvironment,aswellasthenatureoftheorganism(O)throughtheprocessoflearning.Heredity,ontheotherhand,remainsunchangedbutactsonacontinuallychangingorganism.Justasinthepreviousdiagram,theactivityoftheorganismmodifiesitself,butthistimethearrowsleadthroughbehaviorandthephysicalenvironmentbeforefeedbacktakesplace.

onanother,andthearrowsallpointinonegeneraldirection,indicatingthepassageoftime.

Thediagramsreflecttwofundamentaleffects.Oneisthatanorganismundergoescontinualchangeanddevelopment,sothatneitherbehaviornorphysiologyandstructurearethesameatonepointintimeasatanearlierone.Thesecondeffectisthatanorganismchangesitselfbyitsownactivity.Thisisthefundamentalconceptoffunctionaldifferentiation.Earlyinlifethesechangesoccurmostlythroughtheprocessofgrowth.Bydifferentialgrowthandother

occurmostlythroughtheprocessofgrowth.Bydifferentialgrowthandother

4fj$\s

\

/

(2)

N.

B.B:

/

Fig.17.3.—Thefunctionaldifferentiationofasocialrelationship.Bothorganisms(01?02)stimulateeachotherat(2),resultinginanextremelycomplexdiagramoffeedbackandinteraction.Thebehaviorofanindividualinasocialrelationship(BxandB2atthebottomofthediagram)dependsupontheheredityandpastenvironmentoftheotherindividualaswellashisown.Further,hisownheredityandenvironmentaffecthimthroughtheotherorganismaswellasdirectly.Theeffectofadevelopingsocialrelationshipisthusamutualmodificationofbehaviorandthecreationofsomethingnew.

physiologicalprocesses,anembryochangesandmodifiesitsowncapacitytodevelopfurther(Fig.17.1).Laterindevelopmenttheorganismbeginstochangethroughtheprocessoflearningaswellasgrowth.ThetwoprocessesarecombinedinFigure17.2asifoneprecededtheother,butthevactuallyoverlap.Inthisdiagramwehaveindicatedthatheredityandtheenvironmentcontinuallyactuponanorganism,whichisalsoatanygiventimetheresultoftheirpastaction.Thereisanewcomplicationinthatbehaviormaychangethephysicalenvironment,aswellaschangingthenatureoftheorganismthroughtheprocessoflearning.Thischangeinenviron-

SOCIALGENETICS423

mentisreflectedinfuturebehavior.Justasinthepreviousdiagram,theactivityoftheorganismmodifiesitselfandhenceitsfutureactivity,butthistimethearrowsleadthroughbehaviorandthephysicalenvironment.

Figure17.3showstheresultofsubstitutinganotherindividualorganismforthe

Figure17.3showstheresultofsubstitutinganotherindividualorganismforthephysicalenvironment.Theresultisanenormouslycomplicateddiagram.Thebehaviorofanindividualinasocialrelationshipdependsnotonlyuponhisownheredityandpastenvironment(experience),butalsoonthoseoftheotherindividual.Furthermore,thearrowsfromhisownheredityandpastenvironmenteventuallyleadthroughhisbehaviortotheotherindividualandproducearesponse,whichinturnmodifieshisownbehavior.Theresultisthemutualmodificationofbehaviorandthecreationofsomethingwhichisimpossibleforeitherindividualtoachievebyhimself:asocialrelationship.

Doesthismakeitimpossibleeithertheoreticallyorpracticallytoanalyzetheeffectofheredity?Thediagramsindicatethatheredityisnot,asfarasweknow,modifiedbytheactivityoftheorganism.Theheredityofanindividualremainsaconstant,butthefactthatitactswithinacontinuouslychangingorganismmakesfordifficulties.

Aswefoundinthecaseofthedevelopmentofthedominancerelationshipinpuppies,wecanpredicttheactionofheredity,providedwehavereasonablypurebreedingstrainsdevelopingwithinauniformenvironment.Wecanpredictthatfoxterriersrearedinlargelitterswiththeirmotherswilldevelopseriousfightingabouttheageof7weeksandwilleventuallyworkoutdominanceordersinwhichthemalesarecompletelydominantoverthefemales.Wecanalsopredictsomeoftheotherpossibilitiesbasedonexperimentalevidence.

However,wherewedonothavepurebreedingstocksandwhereheredityisunknownexceptthroughitsexpressioninanindividual,thereisafarmoredifficultproblem,andthisistheonewhichwefaceinahumansociety.Inordertopredictthebehaviorofahumanindividualweneedtoknowhisbasiccapacitiesforthedevelopmentofsocialbehavior,irrespectiveofhowtheyhavebeenmodifiedbyenvironmentanduse.Forexample,weneedtestsofaggressivenesswhichwillmeasureaperson'scapacitytodevelopaggressivebehaviorwithoutreferencetotheamountthathehasactuallydeveloped.Sincesuchcapacitiesarebasicallyphysiological,ourhopeofsuccessliesinthedevelopmentofphysiologicaltests.Ifwecouldmeasurethedegreeofemotionalarousalinthecentralnervoussys-

ten3uldhaveameasurementofonetraitinvolvedinthe

.icitytodevelo::_.ss.Ourstudieswithdogshavenot

proceededfarinthisdirection,butwedohaveonesuchphysiological

proceededfarinthisdirection,butwedohaveonesuchphysiologicalmeasurementconnectedwiththearousalofemotion,name.

artratereaction,inwhichtheterrierswerequitedifferentfromallthe:

otherpracedisfortestsofdifferentsortswhichcan

gibdsoonenoughindevelopmentsothatenvironmentalopportunitiescould,ifneedful,beadjustedtobasiccapacities.Inthisdiesofthedogareonlymoderatelyencourag:gDifferencesinaggressivebehaviorarenotreadilvrecognizableuntilabc~_therdifferencesinbehavioroccurearlier,

buttheyarenotdirectlycorrelatedwithadulttraits.Infact,itlooksas::theearliestnofsocialbehaviorisquitevariable,indi-

catingforbehavioraldevelopmentareatE

quiteflexible.

_:basicinformationonearlydevelopment,wewouldeonlvalistofcapacities.Actualbehaviorwoulddependonwhetherornotthesecapacitieswereinfactdeveloped.Consequentlyif;uratepredictionofthebehaviorofanadultindividual,wemustworkintermsofthepotentialdevelopmentofcapacit:inimportantearlvsocialrelationships.Fortunately,thenumberofsuchrelationshipsislimited,orthetaskof:riptionwouldbeimpossiblvdifficult,complicatedasitisbythephenomenonofculturalchan^

illchancreisdeterminedbvthebiologicalmechanismfortransmittingbiologicalheredityfromonegenerationtoanother,soculturalchangedependsonthebasicmechanismfortransmittincrlearnedinformationfromonegenerationtothenext.:sthemechanismoflearninghasthesamefundamentalrelationshiptotheoriesofculturalchangethatthemechanismofMende-lianhereditvbearstothetheorvoforganicevolution.Aswehaveseeninpastchapters,thetwobasicmechanismsarenotentirelyindependentofeachother,andtheproblemofhowheredityaffectsthecapacity-tolearnconsequentlyhasgreattheoreticalimporta:

edityandthecapacitytolearn.—.Althoughtheseexperiments:lidedbythegeneralconceptofsocialbehavior,theproblemofindividualdifferencesinlearningandproblemsolvingseemedsoimportanttousthatwedevotedalargenumberofourteststoanattempttomeasurethedifferentiallearningcapacitiesofdogbreedsandindividuals.

ofdogbreedsandindividuals.

beganwiththeideathatthestudyofdevelopmentwouldbe

SOCIALGENETICS425

importantbecausethiswouldenableustoobservethebehaviorofyounganimalsbeforetheyhadbeenmoldedbytheenvironmentandwhiletheyweremorecompletelycontrolledbyheredity.Wethereforeexpectedtoseetheeffectsofgeneticspureandundefiledintheyoungpuppy.Thisideaturnedouttobesomewhatnaive,forwefoundthatmanyofthecharacteristicbreeddifferencesinbehaviordidnotappearinearlylife,andthiseventuallyledustotheconceptsofthedevelopmentanddifferentiationofbehavior,affectedbyboththeprocessesofheredityandthoseoflearning(Scott,1957).

Insteadofshowingstereotvpedbehavior,ayoungpuppyconfrontedbyanewsituationusuallytriesoutonepatternofbehaviorafteranother.Ifoneoftheseseemstowork,heislikelytorepeatitonsubsequentoccasions,withtheresultthathisbehavioreventuallybecomeslessvariableandmoreconsistent.Thustherearetwoopposingprocessesinanybehavioraladaptationwhichinvolveslearning.Oneoftheseisvariation,whichpermitsimprovementofperformance,andtheotherishabitformation,whichfixesperformance.Hereditymayalterthebalancebetweenthesetwoprocessesineitherdirection.Forexample,Shetlandsheepdogsformfixedhabitsveryreadily,particularlythoseinvolvinginhibitorytraining,whereasbeaglesformsuchhabitslessreadilythantheaveragedog.Althoughhereditythusdeterminesdifferencesbetweenthebreeds,thefinallimitsonbehavioraresetbytheprocessofhabitformation.

Effectoflearningonhereditarydifferences.—Oncehereachestheageof5or6weeks,apuppyhasawidechoiceofbehaviorpatternswhichcanbeusedinanygivensituation.Aswehavepointedoutinearlierchapters,therewereseveralkindsoflearningsituationsincludedinthosewegavethedogs.Oneofthesewasaproblemwithonlyonecorrectanswer,asolutionwhichweimposeduponthedog.Thisisthemethodof"forcedtraining,"well-knowntoprofessionaldogtrainers.Inasituationlikethis,hereditycanmodifythespeedwithwhichthedogacceptsthetraining,asintheleash-controltest,andalsothedegreeofperfectionwithwhichheperformsthespecifiedmovements,butithasrelativelylittleeffectontheendresult.Whenforcedtrainingisimposedontwobreedsofdogs,thefinaloutcomeisthattheybecomemorealikethantheywereinthebeginning.

Inanothertypeoftrainingthepuppyissubjectedtolessrigidcontrol.Whenweweretrainingpuppiestobeweighed,wedidlittlemorethanholdourhandsnearthepuppytokeephimfromfallingoffthescales.Fromthepuppy'spointofview,thegoalofhisbehaviorwastogetoffthescalesandbackonthefloor,andthiswas

achievedattheendofoneminute,nomatterhowheacted.Inthissituationthecockerspanielsusuallydevelopedthebehaviorpatternofsittingquietly,whileterriersandbasenjisdevelopedthatofconstantstruggling.Geneticdifferencesinfluencedthechoiceofthebehaviorpattern,andtheendresultwasthatthethreebreedsgotfurtherapartastheygrewolder.However,geneticsdidnotcontroltheanimal'sbehaviorsoexactlythateverycockerspanielalwayssatquietlyandeveryterrieralwaysstruggled.Whatitdiddowasinfluencetheprobabilitythatthesereactionswouldappear,ratherthancontroltheminanyironcladway.

Mostofourperformancetestsinvolvedfindingagoalwherefoodwasavailable.Therewasacorrectsolution,butthepuppyhadtofindithimselfinsteadofhavingitforceduponhim.Such"problem-solving"testsarenaturalonesforhuntinganimalswhomustfindtheirfoodunderavarietyofsituations.Althoughwetriedtodesignthetestssothatonlyonesolutionwaspossible,weusuallyfoundthatthepuppiesattemptedagreatvarietyofsolutionsandoftenperfectedoneswhichwedidnotconsiderthemosthighlyadaptive.Asthetheoryoftheadaptivefunctionofbehavioralvariabilitywouldpredict,thevshowedmuchmorevariationofbehaviorintheearlypartsofthetestthanlateron.However,insomeofthesetests(suchasthespatial-orientationproblem,inwhichthedogsweregivenaseriesofincreasinglydifficultproblemsonthesameapparatus),thedifferencesbetweenthebreedsremainedproportionallythesamefromfirsttolast.Behaviorbecameagreatdealmoreconsistentundertheprocessoflearning,buttherelativeamountofvariationproducedbyheredityremainedthesame.

Thustheeffectoflearningcanbetoeitherreducehereditarydifferences,magnifythem,orkeepthemthesame,dependinguponthekindoftrainingorproblem-solvingsituationinvolved.

Complexityofinteractionbetweenheredityandthelearningprocess.—Learningisonlvonemechanismbvwhichtheeffectsofheredityareexpressedinhighlycomplexways.Asourexperiencewiththeheredityofseasonalbreedingshows,itispossibletogetahighlycomplexexpressionofhereditvinthephysiologicalfactorswhichunderliebehavior,aswellasintheinteractionofhereditywith

factorswhichunderliebehavior,aswellasintheinteractionofhereditywithlearning

Furthermore,wefoundthathereditaryeffectsuponbehaviorwerehighlyspecificandthatwegotclear-cutindicationsofheredi-tarvdifferencesonlvwhenweworkedwithvervsimplebehaviorpatterns.Inmostproblem-solvingsituations,behaviorishighlvcomplexandmanybehaviorpatternsareused,combined,andrecom-

SOCIALGENETICS427

binedwitheachother.Theresultisthatwhilecomplexperformanceandintelligencetestsshowindicationsoftheeffectofheredityinbothpurebreedsandhybrids,neitherthekindsofsolutionsnorthedegreesofsuccessareinheritedinanysimpleMendelianfashion.

Atthispointwemightemphasizethefactthatourworkconflictswithseveralpopularnotionsoftheeffectofheredityonbehavior.Oneisthatthereareafewbasichereditarytraitswhichappearinallthebehayiorofanindividualandmakehisbehayiorpredictableandunderstandable.Perhapsthisiswhatisordinarilymeantbytheterms"character"and"personality."Althoughitmaybepossibleforhumanbeingstodeyelopsuchconsistentbehayiortraitsthroughlearning,thereisnoindicationinourresultsthatheredityactsinanysuchsimplefashion.

Anothermistakennotionisthatthereissuchathingas"generalintelligence."Asweshowedinanearlierchapter,adogbreedmayrateveryhighinonetestsituationandquitelowinanother,withlittleuniformity.Ourgeneralimpressionisthatanindiyidualfromanydogbreedwillperformwellinasituationinwhichhecanbehighlymotiyatedandforwhichhehasthenecessaryphysicalcapacities.Hereditymaylimitbothmotiyationandcapacity,butinhighlyspecificways.Ifwecomparetheseresultswiththehumansituation,welikewisefindnogeneralconfirmationoftheexistenceofafactorofgeneralintelligence(Anastasi,1958).Humanbeings,howeyer,havestillanothercapacity(orcapacities)whichisprobablyaffectedbyheredity,andthatistheabilitytolearnanduselanguage.Thismaychangethesituationfromthatwhichwefoundindogs,forinhumanbeingsthelackofonlyonespecificgroupofcapacities;i.e.,theabilitytouselanguage,wouldbeageneralhandicaptoalmostallaspectsoflearning.

Stillathirdpopularnotionisthatindiyidualsfallintobehavioral"types"andthatthesearesomehow7relatedtophysiqueorspecialphysicalcharacteristics.Our

thesearesomehow7relatedtophysiqueorspecialphysicalcharacteristics.Ourresultsindicatethatevenindogswearedealingwithpopulationsinvolvingcontinuousvariationandthat"types"haverelativelylittleimportance.

Wemustconcludethatanyattempttoimprovethecapacitiesforlearningandproblemsolvingbygeneticmethodsislikelytobemostsuccessfulwhendoneinahighlyspecificway,asithasbeendoneforthedogbreeds.Evenintheseanimals,thebreeddifferencesusuallyarenotgreat,providedallbreedsaregivenanequalamountoftrainingandopportunitytolearn.Thereisstillanenormousamountofgeneraladaptivecapacityinthespecializeddogbreeds,andapurebreddogcanlearnmanythingsbeyonditsownspecialty.

Thechiefdifferencesbetweenthebreedsseemtolieintheamountoflimitationproducedbythesespecialcapacities.Certainbreedsarequitelimitedwithregardtothesituationsintowhichtheycanadaptwell,andothersaremuchmoregeneralized.Forexample,withonlyaminimumamountoftraining,thebeagledoesquitewellasarabbithunterandalmostequallywellasahousepet.Mostoftheshepherddogscanbecomeindependenthuntersofbiggame(aswhencolliesrundeer),buttheyrequireagreatdealofspecialtraininginordertobecomeeithersuccessfulshepherddogsorhousepets.

Therehasneverbeenanydeliberateselectionofhumanbeingscorrespondingtothatindogs,althoughmodernhumansocialorganizationcanconceivablyhavethiseffectindirectlybyselectingcapableindividualsofbothsexesforcollegetrainingandthenbringingtheselectedindividualstogetheratthematingage.However,thecapacitiesusefulinhighereducationaresobroadandcomplexcomparedtotherelativelysimplecapacitieswhichcanbeeasilymodifiedbyageneticselection,thatitisunlikelythatevensuchassortivematingwilleverproduceahighlyspecializedanduniformpopulationhereditarilydifferentfromtherest.Mostindividualsarelikelytohavecertainspecialcapacitieshighlydevelopedandothersrelativelypoorlydeveloped.Becauseofthewidespectrumofadaptabilitypresentinmostindividuals,heredityshouldnotbethemostimportantlimitingfactorindeterminingtheirlivesandbehavior.Infact,aswehaveseenabove,themostimportantlimitingfactoronbehavior,andparticularlythatlimitingthedifferentiationofbehaviorbetweenindividuals,islearningandhabitformation,andourchiefpracticalproblemistodesignasocialenvironmentwhichwillprovideanopportunitytoexpressinusefulandpleasurablewaystheenormousamountofvariationinbehaviorofwhichhumanbeingsarecapable.

Howdoesheredityaffectthecapacitytolearn?—Oneoftheobviouswaysin

Howdoesheredityaffectthecapacitytolearn?—Oneoftheobviouswaysinwhichheredityaffectsthecapacitytolearnisbylimitingphysicalcapacities.Adachshund,forexample,willneverbeabletolearntocatcharabbitbychasingit.Suchlimitations,inturn,haveanimportanteffectonlearnedmotivation,whichissolargelydependentuponsuccess.Inaddition,thedogbreedsshowmoredirecthereditarydifferencesinmotivation,huntingdogsinourstrainsshowingmoreinterestinFoodthanrepresentativesoftheworkingbreeds.Differencesinemotionalresponsivenessareimportantandmaymakethelearningofcertaintaskseasierorharder.

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Oneofthemostinterestingmodificationsoflearningisthatofhereditaryshiftingofthebalancebetweenvariabilityofbehaviorandfixationbvhabitformation.Thesedifferences,however,appeartobemodificationsoftheperipheralprocessesoflearning(i.e.,motivationtolearn)ratherthanofthecentralphenomenonofassociation.Alldogscanmakeassociations,anditispossiblethatthiskindofabilitvissofundamentalthattheanimalcannotexistwithoutit,thatlearningisasbasicallyimportanttoexistenceasismetabolism,andaslittlesubjecttochange.

CULTURALEVOLUTIONANDBIOLOGICALCHANGE

Thisbringsustoathirdbasicproblemofsocialgenetics:howdoessocialorganizationaffecttheprocessofbiologicalinheritanceandthusaffectbiologicalevolutionarychange?Theexistenceofsocialrelationshipsinananimalsocietyusuallyproducesamatingsystemofsomesort,sothatgenesarenotpassedfromonegenerationtothenextinarandomfashion,andthisfactinturnmayeitherspeeduporslowdownevolutionarychange.

Stabilizingeffectofsocialorganization.—Fromatheoreticalpointofview,thegeneraleffectofastablesocialorganizationonananimalpopulationshouldbetoslowdowngeneticchanges.Wehaveseenthattherearetwobasickindsofprocessesoffunctionaldifferentiationgoingon:physicalandanatomicaldifferentiationbasedontheprocessofgrowth,andbehavioraldifferentiationbasedontheprocessoflearningaswellasongrowth.Forachangeinhereditytosurvive,itmustproduceafavorableeffectonatleastoneoftheaboveprocesseswithoutproducinganoverridingunfavorableeffectontheother.Theadditionofstillanotherprocess,thedifferentiationofbehaviorinasocialrelationship,producesathirdformoforganizationinwhichthehereditarychangemustproduceafavorableoratleastneutraleffect.This,ofcourse,still

changemustproduceafavorableoratleastneutraleffect.This,ofcourse,stillfurtherreducesthelimitswithinwhichpermanenthereditarychangecantakeplace.Thesedevelopmentalprocessesareallpartiallydependentupononeanother,andsowefindthatthesocialbehaviorpatternsandthesocialdevelopmentofaspeciesaredirectlyrelatedtothenormalsocialorganizationofthespecies,andthatadisruptionofdevelopmentproducesadisruptioninsocialorganization.

Inaddition,anypopulationinaconstantenvironmenttendstoapproachastateofgeneticequilibrium,andthemoreconstantthesocialenvironment,themorestablethegeneticsystem.Evenifthe

stateofequilibriumistemporarilydisturbed,asbythechangeinenvironmentproducedbycivilizedliving,anewstateofgeneticbalanceiseventuallyreached.

Culturalevolutionandbiologicalevolutioncompared.—Inhumanpopulationstheseprocessesoperatingtoproducegeneticstabilityareopposedbyotherforcesmakingforsocialchange.Agreatmanyanimalsocietiesshowthebeginningsofculturalinheritance.Sometimesanimalsinheritstructuresbuiltbytheirancestors,asinthecaseofprairiedogburrows.Ortheymaylearnbehaviorfromolderanimals,asyoungdeerlearntobefearfulofhumanbeingsfromtheirelders.Totheseabilities,humanbeingshaveaddedthecapacityforspeech,whichenormouslymagnifiesthepossibilityoftransmittinglearningfromonegenerationtothenext.Furthermore,whatislearnedthroughspeechbecomesalmostcompletelyindependentofbiologicalheredity,withtheresultthatculturalchangeordinarilyproceedsmuchfasterthanbiologicalchange.

Anyonewhocomparesbiologicalandculturalevolutionbecomesfascinatedwiththeresemblancesbetweenthetwo.Languagesseemtoevolveinmuchthesamewayasspecies,andonecandrawaphylogenetictreeoflanguageswhichisnodifferentinformfromthephylogenetictreeofthespeciesoftheanimalkingdom.Yetthetwokindsofchangerestonentirelydifferentprocesses,onebeingMendelianinheritanceandtheothertheprocessoflearning.

InMendelianheredityaparentpassesalongtoeachchildonlvoneofeachpairofgenes,selectedpurelvbychance.Withtheusualnon-inbredhumanparent,theresultisanarrangementofgeneticfactorsinnewcombinationsinthenextgenerationwiththevirtualcertaintythatnoneofhischildrenwillhaveexactlythesamecombinationashisown.Similarly,thebasiccharacteristicofthe

thesamecombinationashisown.Similarly,thebasiccharacteristicoftheprocessoflearningisthateachchildmuststartalloveragainfromthebeginning.Itisimpossibleforhimtoacquireexactlywhathisparentshavelearned,becausepartofhisenvironment,asdistinctfromtheirs,iswhatthevattempttoteachhim.Theprocessoflearningisbothselectiveandorganizational;consequentlytheinformationlearnedbythepreviousgenerationisneverpassedalongcompletelvandneverorganizedinexactlythesameway.Biologicalandculturalheredityaresimilarinthattheyarebothfundamentallyunstablesystemswhichmakechangeinevitable.

Thereisonebigdifferencebetweenthetwosystems.Culturalheredityiscumulativeandhasbecomemuchmoresowiththeinventionofwrittensymbolsandrecords.Biologicalheredity,ontheotherhand,isnon-cumulative.Eachindividualhasonlvthesame

numberofchromosomesandgenesashisimmediateancestors.Thisisanotherwayofstatingthatlearnedbehaviorcanbeinheritedculturallybutnotbiologically.

Theresultisthathumansocietiesinevitablychange,andchangewithgreatrapidity—sofastthatbiologicalchangeisinevitablyleftfarbehind.Wehaveeveryindicationthatthehumanraceisphysicallyquitesimilartowhatitwastenthousandyearsago,yetthisisthetimeduringwhichwehaveprogressedfromprimitivehuntingtribestomodernindustrialcivilization.Ifanything,theprocessofculturalchangeseemstobespeedingupratherthanslowingdown.

Heredity,learning,andculturalevolution.—Evolutiontowardwidercapacitiesforadaptationisageneraltendencyintheanimalkingdom,althoughtherearemanyexceptionsinthecaseofspecieswhichhavebecomespecificallyandnarrowlyadaptedtoaparticularenvironment.Specializedspeciesarelikelytobecomeextinctwhentheenvironmentchanges,withthelongtermresultthatthosewhichsurviveusuallyhaveawiderangeofbehavioralandphysiologicaladaptability.

Thisgeneraltendencyinvolvesade-emphasisofbehaviororganizedonapurelyhereditarybasis,forsuchbehaviorcanonlybeadaptiveinacompletelystableenvironment.Alongwiththiswefindanincreasingemphasisonvariablebehaviororganizedbylearning.Moreover,theprocessesofculturalchangeandculturalevolutionautomaticallyproduceanunstableandchangingenvironment.Inhumansocietiessuchchangeshavealwaystakenplacebetweenonegenerationandthenext,andinthecurrentspeed-upofculturalchangetheyare

generationandthenext,andinthecurrentspeed-upofculturalchangetheyarebeginningtotakeplaceevenwithinasinglelifetime.Consequentlythereareandwillbeincreasingdemandsforpersonswhoareflexibleandadaptiveor,inshort,whohaveincreasedlearningcapacities.

Thekindsofeffectsofheredityuponlearningcapacitieswhichwehavedescribedindogschieflycontributetobreedandindividualdifferenceswithinthespecies,increasingtherangeofadaptabilityofthespeciesratherthanthatoftheindividual,whoseownbehaviormay,infact,belimitedbythem.

Therearenobreedsinthehumanspecies,butthereisanenormousamountofindividualgeneticvariability.Wehaveeveryindicationthatourspeciesasawholealreadyhasawiderangeofadaptability,inhabitingasitdoeseveryclimateontheglobeandtakingpartininnumerableproductiveanddestructiveoccupations.Individualhereditaryvariationhastheeffectofmakingthisrange

ofadaptabilityforthespeciesevenwider,andthisinturnhastheeffectoffacilitatingculturalchange.Thuswecanconcludethatthereisasynergisticrelationshipbetweenhereditaryvariationinbehavioralcapacitiesandthespeedofculturalevolution.Hereditaryvariationwidenstherangeofadaptability",permittingculturalchange;andculturalchange,inturn,permitssurvivaloflargerpopulations,withtheconsequentincreasedpossibilityofhereditarvvariation.

Now,whateffectdotheserapidchangesinhumansocialenvironmenthaveuponthedog?Dogsreflectthecultureinwhichtheylive.IntheMiddleEastthereareessentiallvonlvthreekindsofdogs:salukisusedforgazellehuntinginthedeserts,largeherdingdogsusedbvKurdishshepherdstoprotecttheirflocksfromwolves,andmongrelswhichchief!vactasscavengersinthecities.Bvcontrast,

OrJO

inmodernFrance,wheredogsarechieflvusedonfarms,therearesomeseventeenbreedsofshepherdandstockdogs.InEngland,wherehuntinghasbeenapopularsportinallclassesfromasfarbackastheMiddleAges,therewerein1959twenty-sixrecognizedbreedsofsportingdogs.

Wecanthinkofhumansocialchangeasprovidingtheopportunityforthephenomenonofcanineadaptiveradiation.Eachsocialchangeopensupawholenewenvironmentfordogs,andtheexpansionoftheirnumbersfromsmall

newenvironmentfordogs,andtheexpansionoftheirnumbersfromsmalloriginalgroupsprovidesanopportunityforrapidbiologicalchange.InmodernEuropeandtheUnitedStatesincreasedwealthandurbanlivinghasopenedupawholenewenvironmentfordogsassocialcompanions,andwemayexpecttoseethebreedschangedandmodifiedinthatdirection.Thusweseethegreatpopularityofthebeagleasachildren'spet,beaglesbeingextremelvnan-aggressivedogswhichadaptwelltofamilylifewithaminimumoftraining.AnotherbreedwhichisbecominghighlypopularistheChihuahua,whosesmallsizeandsturdyphysicalconstitutionmakeitanidealanimalforapartmentdwellers.Itwillbarkasvigorouslvasanywatchdog,butistoosmalltobitethepostman.

Moderndogsalsofillmoreserioussocialfunctions.Companiondogsprovideasolutionformanyofthepsychologicalstrainsimposedbyculturalchange.Theelderlycouplewhosechildrenhavemovedawaycanadoptapuppyasachildsubstitute,andthelonelybachelororspinstermaykeepadogasadependablecompanion.Wemayexpectthatinthefuturetherewillbedeliberateaswellasunconsciousattemptstodevelopbreedswhichwillsatisfythesesocialneeds.

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Inthelongrun,theeffectofselectingdogsforfirstoneculturalenvironmentandthenanotherwillbetoproducerandomselection,eventuallyleadingtopermanentgeneticchange.Althoughwolflikecharacteristicsarestillpreservedinvariousdogbreeds,itwouldbeextremelydifficultatthispointtore-createanythinglikeawolffromasinglebreedlikethebeagle.Ingeneral,wecanpredictthataslongasbreedsaremaintainedasseparatepopulationstherewillbeacontinuousprocessofchangeindirectionsdeterminedbytheasyetunpredictablecourseofhumanculturalchange.Biologicalevolutionofthedogwillcometoastandstillonlyifbreedsandlocalvarietiesarenolongermaintainedseparatelyandallanimalsallowedtomateatrandom.

Thislastisessentiallywhatisnowhappeningtothehumanpopulationasaresultofculturalchange.Thekindofculturalchangepresentlycharacteristicofhumanpopulationsseemstohavehadtheneteffectofslowingdownhumanbiologicalchangewhilespeedingupthatofthedog.Itistruethathumanbeings,likedogs,continuallyhavenewculturalenvironmentsopeneduptotheminwhichonekindofindividualmaybemoresuccessfulthananother,buthumangenerationsaresolongandculturalchangeshavebecomesorapidthatthereisnotimefordifferentialselectiontohaveanyconsiderablebiologicaleffect.Eventhissmallpossibilityisnullifiedbytheenormousnumbersinhuman

thissmallpossibilityisnullifiedbytheenormousnumbersinhumanpopulations.

Toconclude,theeffectofculturalchangeuponhumansocietieshasbeentoreducedifferentiationbetweensmallhumansubpopu-lationsandtoincreasethedifferentiationbetweenindividualswithinapopulation.Indeed,thereisasynergisticrelationshipbetweenculturalevolutionandindividualbiologicalvariability.Theprincipaleffectofculturalchangehasbeentowidenthelimitswithinwhichvariouskindsofhumanbeingscanexistandcreateawidervarietyofsocialenvironmentswithintheselimits.Oneofoureffortstowardconscioussocialchangeshouldbeinthedirectionofrecognizingthisvarietyandprovidingsocialflexibilitywhichwouldpermittheusefulandhappydevelopmentofinevitablydifferentindividuals.Oneofourbasicproblemsinthistaskwillbetorecognizeindividualcapacitiesandassistpeopletofindfittingandcongenialsocialenvironments.Suchassessmentsarecrudelydoneatpresentandperhapscanneverbedoneperfectly.Infact,aperfectjobistheoreticallyunnecessary,sinceoneofthebasiccapacitiessharedbythemajorityofhumanbeingsisthatofadjustmentandadaptationtomanydifferentsortsofenvironments.


Anotherfundamentalcontributionofascienceofhumannaturewillbethediscoveryofthelimitsofgeneraladaptation.Thiswillenableustorecognizeandavoidharmfulanddisappointingsocialchangeinadvance:tochooseinsteadmorebeneficialsocialchangesandtobringthemaboutinpeacefulandproductiveways.

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Baege,B.,435

Bahrs,A.M.,435

Baker,J.A.,15,435

Baker,P.T.,82,354,435

Banks,E.,97,226,439

Bayer,L.M.,418,435

Bayley,N.,418,435

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Berg,I.A,436

Bliss,E.L.,436,441

Bliss,J.Q,436

Blome,R.,47-48,436

Blume,D.,93,436

Bose,W.K.,148,442

Bowlby,T.,149,436

Boyden,A.,44,436

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Burgher,J.A.,435Burns,M.,4,389,436

Caius,J,45-47,51,436

Calvin,A.D.,146,441

Carpenter,C.R.,152,436

Castle,W.E.,263,266,436-37

Cattell,R.B.,443

Chambers,R.M.,437

Chapin,J.P.,48-49,437

Charles,M.S.,93,121,437,444

Chaucer,G.,45

Cherner,M.,443

Christake,A.,100,439

Clark,F.,93

Clark,L.D.,105,439

Cloudman,A.M.,338,437

Cohen,C,295,437

Coleman,C.E.,50,437

Collias,N.E,129,143,437

Corbin,J.E.,327,437

Cornwell,A.C,98,226,437,445

Crisler,L.,62-66,71,75,79,140,437

Crow,J.F.,409,437

Dahr,E.,35,37-38,437Darwin,C,29,51,274,404,437Dawson,W.M.,4,334,437Degerb0l,M.,34-35,437Denenberg,V.H.,385,437,443Deshaies,D.,444Dice,L.R.,437DiMascio,A.,437Dobzhansky,T.,333,410-11,437Dollard,J.,144,442Doughty,M.F.,435

449

AUTHORINDEX

AUTHORINDEX

Dubuis,E.,439Duerst,U.,45,438

Easier,C,97,226,314,439

Ellerman,J.R,438

Elliot,O.,73,102,105,109,124,128,

144-45,177,193,236,438,445Erlenmeyer-Kimling,L.,324,440Etkin,W.,81,438Eysenck,H.J.,436

Fabricius,E.,142-43,438Falconer,D.S.,297,298,391-92,438Feider,A.,144Fielde,A.M.,438

Fisher,A.E.,105,132,145,438,445Fredericson,E.,122,305,438,444Freedman,D.G.,105,124,128,438Fuller,J.L.,4,21-22,67,93,97-98,100,105,106,121-23,132,197,226,282,295,314,324,389,391,435-39,444,446Freud,S,3,144

George,W.C,323,439

Gessner,C.,45

Gibson,E.J.,93,446

Gillespie,J.H.,435

Gillum,0.,439

Gilmore,R.W.,69,436

Ginsburg,B.E.,62,67,74,76-77,131,

141,148,394,402,439,445Goldman,E.A,31,37,51,65,447Gordon,T.M.,Jr.,439Gower,J.C.,359,439Grant,D.A.,241,439Gray,A.P.,52,439Gray,P.H.,143,146-47,440Guilford,J.P.,186,440Guttman,L.,210,440

Haag,W.G.,35,440

Hafez,E.S.E.,437,439

Hafez,E.S.E.,437,439

Hall,C.S.,6,194,440

Hammond,W.H,339,440

Hammons,H.G.,400,440

Hansen,E.W.,440

Harlow,H.F.,143,145,226,440,442

Harlow,M.K.,440

Harman,P.J.,86,88,440

Harris,D.,444

Ilatt,R.T.,34,440

Hayes,C,143,440

Haves,K.J.,387,440

Hebb,D.O.,26,353,440

Ht-inroth,O.,142

Hess,E.H.,143,440Hildebrand,M,31,37,51,440Hilzheimer,M.,29,440Hirsch,J.,324,440Howells,W.W.,339,440Humphrey,E.,350,440Hunter,W.S.,242,441

Igel,G.J.,146,441Iljin,N.A.,52,441

Jackson,H.H.T.,31,37,447James,H.,146,441James,W.T.,86,441Jetter,W.,437Jinks,J.L.,324,436Jolicoeur,P.,43,51,83,441

Kaiser,H.F.,348,441

Keeler,C.E.,334,441

Kellogg,L.A.,143,441

Kellogg,W.N.,143,441

King,J.A.,62,73,105,124-28,144,167,

177,282,438,441,444-^5Klyavina,M.P.,98-99,441Kobakova,E.M.,441Koehler,W,226,441Krushinskii,L.V.,59,385,441Kulp,J.L.,33,441

Lacey,B.C.,204,441Lacey,J.I.,204,441Lawrence,B.,38,441Lerner,I.M.,391,441Levine,S„385,441Linnaeus,C.,29-30,56Little,C.C,6,338,389,441Lorenz,K.,142-44,441Lumer,H.,441Lush,J.L.,391-92,441

McCav,C.M,72,442McKusick,V.A.,354,442Marston,M.V.,445Martins,T.,109,442Mason,M.W.,435,442Mason,W.A.,226,442Mather,K.,187,264,324,442Matthew,W.D.,33,442Matthcy,R.,52-53,442Meeh,L.D.,74-75,435,442Menzel,R.,442Miller,N.E.,144,442Mohnnan,R.K.,437Morris,D.D.,444Morrison-Scott,T.C.S.,438

Morton,N.E..409-10.442Marie,A..51,61-65,75-76,140,39S,416,442

Nice,M.M.,143,442

Ogburn,W.F.,14S,442

Packard.A.S..29.442

Parrv.H.B..93.442

Paufv,L.K..45.442

Pavlov.I.P..97.144.195.442

Pawlowski.A.A..159.443

Pfaflenberger.C.J.,17,109,21S,443

Poggiani.C.445

Pribram,K.H.,439

Reed.C.A..34-35.436,443

Reed,S.C.400.410.443

Reed,S.C.400.410.443

Rheingold.H..171.440.443

RibbandsC.R..142.443

Robson.J.A..435

Ross,S..90-91,102,443.445

Rosvold.H.E..439

Royce,J.R.,323,36S-70,443

Sarris.E.G..6S.446

Schenkel.R.,62-65,79,443

Schlager.G..359

SchmFdt.J.R..370,435

Schwab.J.J..333.443

Scott.J.P..5.51.57.59.90.102,109.

113,116.119-20.122.129,143.153.

159.169.197.236.26.5-66.282,324,.394.414.416-17,425,435,438,

439.443-45Searle.L.V..6.194.256.388,445Seitz.A..53.445Seton.E.T..69.445Shade.C.341

Sheldon.W.H.,339,340-43,445Sherif.M..444Singh.J.A.L..147-4S.445Skinner.B.F..100,216.445Smith.A.C.50.314.445Smith,M.E.,439

AUTHORNDO451

Stanlev.W.C..87,100,144.445

Stelmakh.L.X..441

Stevens.S.S.,341.445

Stevens.S.S.,341.445

Stewart.P.B..436

Stockard.C.R..6.42.323.445

Strandskov.H.H..36S.445

Studer,T..35,445

Tembrock,G„62-65.414,445Terhune.A.P..163Thompson,W.R..324.439Thurstone,L.L..34S.36S-69,445Tinbergen,X.,109,446Trattner.A..445Trevelvan,G.M.,45,446Troshikhin.V.A.;86.441,446Trvon.R.C.,5,6,446Tudor-Williams,V.,48,446

VanderMerwe,X.J.,50.446Vogd,H.H..445Volokhov,A.A..446VonUexkiill,J.,68,446

Waddington,C.H.,446--41.446Walk.R.D..93.446Waller.M.B..105.439,446Wamer,L.,350,440Waters,R.H.,444Watson,J.B.,3Welker.W.I.,87,446Werth.E.,32,38.54-55.446White.G.,50,446Wilcke.H.L.,437Wilson,M.O..444Wolfe.H.R.,45,442Wright.S..5.263,266,297,314,392,398,408,446

Yokes,R.M..4

Young,S.P.,31,36-37,51,63-65,447

Zahn,T.,167

Zingg,R.M.,147-48,445

"Acquireddrive,"doesnotexplainsocialization,144,146Activity-successfactor,inperformance

tests,372-73Adaptation,limitedbyspecialization,

427-28Adaptiveradiation

dog,36,55-56,398,432

human,400Adoption,inrelationtosocializationprocess,149Africa

human,400Adoption,inrelationtosocializationprocess,149Africa

disappearanceofaboriginalbreeds,399

distributionofbasenjiin,49

distributionofjackalsin,31Africanhuntingdog,30

fossils,33Age

changesinheritabilitywith,201

effectonemotionalreactivity,198-200,201,312-13,315Aggression;seeAgonisticbehaviorAggressivebehavior,breedcomparisons,

136-37Aggressiveness

independentoftimidity,369-70

measuredbydominancetest,137

problemofmeasurementinearlydevelopment,423-24Agonisticbehavior

basenji,261

cockerspaniel,261

dog,6X),84,757s

inemotionalreactivitytest,202

inheritanceofpatterns,267-68

injuvenileperiod,109452

limitssocializationindog,131-32

insocializationperiod,104-6

intransitionperiod,91-92

wolf,64,75-78Agriculturalrevolution,anddog,34Airedale,history,51Allelomimeticbehavior

Allelomimeticbehavior

dog,63,74-75

effectonsocializationindog,131


insocializationperiod,106

wolf,63,74-75America,aboriginaldogbreedsin,399Analysisofvariance

appliedtomatings,298

methods,189-93,298

simplifiedschema,192

seealsoVarianceAnatomy,comparative,evidenceofdog

origin,36-44Ants,socializationin,141-42Arrhythmia;seeHeartrateAssortivemating,effectonhumanbehavior,428Attractionscore,obediencetest,212,214Australia,dingoin,32

Barkingandbarklessness,inheritanceof,

^273-78Barriertests;seeDetourtest;MazetestBasenji

agonisticbehavior,261behavior

inleashtest,306

inmotivationtest,307

inspatialorientationtest,319

SUBJECTINDEX

453

bodvproportions,341

breedingcycle,49,50.67,27

climbingabilityof,219

fearofapparatusin,247

growthcurves,328,330-31

history,48-50

inguinalherniain,389-90

inheritanceofbarkingandbarkless-ness,273-78

manipulativeabilityof,229

origin,296

posturalresponses,288-91

problem-solvingabilityof,258,322

reactiontopassivehandlertest,145

skullmeasurements,40-41,43-44

variationinbodylength,371

seealsoBreedcomparisonsBassethound,skullshape,42Beagle

adaptivecapacities,428

comparedtowolf,402

history,47

otocephalyin,390

asresearchsubject.395


slowhabitformationin,237-38,425

useaschildren'spet,432

useofsenses,79,80

usedincriticalperiodexperiment,122

vocalizationinstrangeroom,122

weightgain,327

seealsoBreedcomparisonsBees,socializationin,142Behavior,3-7Behaviorgenetics

biometricalgoalsfor,323-25

fieldof,413Behaviorpatterns

inCanidae,63-65,414-15

definition,59

ofdogsandwolves,383-84

inheritance,261-94

methodsofobservation,57-58

inrelationtoinstinct,60

singlefactorandpolygenicinheritance,292-93

asunitsofstudy,58-61Behavioralsystems

definition,59-60

ofdogandwolf,61-80

inrelationtoinstinct,60

relationshipsbetween,61Biometricalgenetics,goalsof,323-25Birds,process

relationshipsbetween,61Biometricalgenetics,goalsof,323-25Birds,processofsocializationin,115,

142-43Biting,inreactivitytest,313-14

Blindness,inheritanceindog,389-90

Bloodhound,history,46-47

Bodyposition,inemotionalreactivity

test,313Bodvproportions,breedcomparisons.

341-42Bodysize,inheritance,286-87Bolognese,skullmeasurements,40-41Borzoi

headshape,29

skullmeasurements,40-42

useofsenses,79Bostonterrier,skullshape,42Boxer,skullmeasurements,40-42Brain,sizeindwarfbreeds,42Breed,proportionofvarianceassociated

with,360-67Breedassociations,objectivesfor,393-94Breedcomparisons

aggressivebehavior,136-37

barkingindominancetest,274-75

bodyproportions,341-42

coefficientsofinbreeding,48^19

congenita]defects,406-7

cue-responsetest,241-42

delaved-responsetest,243

detourtest,228-29

developmentofallelomimeticbehavior,106

developmentofheartrate,121-22

developmentofstartleresponse,94

distressvocalization,92

dominance-subordinationrelationship,156-63,419

emotionalreactivitytest,198-203

eruptionofteeth,96

fearresponses,134-36

followingtest,174-75,177

forcedtraining,215-16

goal-orientationtest,217-18

growthcurves,329-31

handlingtest,134-38

investigatorybehavior,137-38

leash-trainingtest,208-9

manipulationtest,230-31

maternalnursingbehavior,171

maternalretrievingtest,172-73

mazetest,234-35,237-38

inmodeofmotivation,387

mortalityrates,405-6

motivationtest,240

motordevelopment,96

motor-skilltest,220-21

obediencetest,213-14

physiqueandbehavior,345-47

problem-solvingbehavior,257-58

SUBJECTINDEX

quietingtest,206-7

retrievingtest,2IS-19

size,329

ikullshape,37-44

spatial-orientationtest,250-52

statisticalmethodsfor,185-93

summarytable,36061

tail-wagging,137-40

timeofopeningofeye,8990

trailingtest,246-47

variancecomponents,30067

seealsoInheritanceBreeddifferences

inendocrineglands,6

andrearingpractices,385-86

seealsoBreedcomparisonsBreedsymbols,key,10Breeding,scientific,indogs,399Breedingcycle

399Breedingcycle

basenji,49-50,67

dingo,67

dog,67

inheritance,278-83

inwolf,dog,andcoyote,278-79Breedingplan,7-11Breeds

aboriginal,inAmericaandEurasia,399

effectofpanmixison,399

factoranalysisappliedto,371-75

geneticheterogeneityin,29,185,295,378,386-87

history,45-51

notequivalenttoraces,82

aspopulations,393-94

useinresearch,394-95

seealsoundernameofbreedBrusselsgriffon,skullshape,42Bulldog

bull-baiting,77

headshape,29

jawshape,38

short-leggednessin,42

skullshape,40-43,400Bulldocr,French,skullmeasurements40

42Bulldoghead,probablvamutation.42Bush-dog,SouthAmerican.30

fossils,33

fossils,33

Canidae

chromosomenumb,ification,30-31fossils,33geographicalOriginanddistribution

32

serologicalrelationships,44-45Canis

ecologyof,31

geneticsof,51-53

interspecifichybrids,52-53Care-dependencyrelationship

development,176-78

dog,153,174Care-solicitingbehavior;seeEt-epimeletic

behaviorCarnivora,classification,30Castle-Wrightformula,foranalysisof

quantitativeinheritance,263-64Catchingtime,testresults,168Chick,criticalperiodforsocializationin.

143Chihuahua

popularityincities,432

size,56

skulls,43

weight,29China,homeofchow,50Chow,history,50

Chromosomes,infamilyCanidae,52-53Classification,biological,seeTaxonomy

ornameofanimalClassification,ofsocialrelationships,152-

53Cleftpalate,inheritance,389Clubfoot,infoxterriers,390Cockerspaniel

agonisticbehavior,261

behavior

inleashtest,306


bodyproportions,341

breedingcycle,278-79

earlylearningin,97

growthcurves,330-31

history,48

hydrocephalyin,390

origin,296

posturalresponses,288-91

problem-solvingabilityof,322

skullmeasurements,40—41.43-44

variationinbodylength,371alsoBreedcomparisonsCollie,adaptivecapacities.428Comfort-seekingbehavior

effectonsocializationprocess.14^

secalsoShelter-seekingbehaviorConditionedresponse,experimentsin

transitionperiod,97-100Conditioning

rel.ttionshiptosocializationprocess,144,146

SUBJECTINDEX

455

455

seealsoLearningConfidence,effectonmazeperformance,

237Confidencescore,obediencetest,212,

214Confinementtest

affectedbyhairlength,336-37

variancecomponents,360Co-ordinatedattackrelationship,dog,

154Correlationalmethods,appliedtogenetic-variance,376-78Covariance,methodofanalysis,236Coyote

appearanceandproportions,37

behaviorpatterns,63-65

classification,31

distributioninNorthAmerica,31

fossils,33

interspecifichybrids,52-53

skullmeasurements,40-41,44

socialbehaviorpatterns,62-65

socialgroups,415Criticalperiodconcept,117-18Criticalperiodhypothesis,testsof,122-

29Criticalperiodforlearning

inretrievingtest,22Criticalperiodforprimarysocialization

inbirds,142-43

boundariesof,118-29

dog,108,111,117-50

dog,108,111,117-50

generalphenomenon,417

inguineapig,143

inhumaninfants,115,147-50

inrhesusmonkey,143

insheep,143Criticalperiods,indevelopment,110-12Cross-fostering,resultsof,186,191Cue-responsetest

breedcomparisons,241-42

hybridcomparisons,308-9

methods,238-42Culturalchange,basedonprocessof

learning,424Culturalevolution;seeEvolution,cultural

Dachshund

comparedtowolf,402

leglength,29,42

skullmeasurements,40-41Defects,structural

indogbreedingmanagement,389-90Delayed-responsetest

breedcomparisons,243^44


methods,242Denmark

domesticationofdogsin,54

possibleoriginofdogin,35

stoneagedogin,34-35Dependency;secCare-dependencyrelationshipDetourtest

test

behaviorduring,227-28


correlationwithtrailingtest,374

effectofmaternalenvironment,284-85

factorloadings

foractivity-successandheart-rate,

372forreactivity,374

methods,19-20,226-27

intestschedule,24

variancecomponents,361-62,366Developmentofbehavior

care-dependencyrelationship,176-78

changesinhandlingtest,176-77

conceptof,16-17

differentiationofbehaviorin,287-92

dog,84-116

dog-humanrelationship,175-80

normalvariationin,119-20

observationalmethods,15-17

problem-solvingbehavior,225-26

processesof,111-12Developmentalgenetics,413Dhole,30

fossils,33Differentiation,growthcurves,332Differentiationofbehavior

fossils,33Differentiation,growthcurves,332Differentiationofbehavior

duringdevelopment,287-92,425

functional,421-22

andgenetics,165-69,181

insocialrelationships,152Differentiationofsocialrelationships,law,

168-69,181-82Dingo

breedingcycle,67

classification,31

origin,32

resultofadaptiveradiation,398

skullmeasurements,40-41Diseasecontrol,methodsof,13-15Distemper,canine,controlof,13-15Dobermanpinscher

history,51

skullmeasurements,40-41Dog

adaptiveradiationof,36,55-56,398.432

SUBJECTINDEX

agonisticbehavior,60,64,75-78

andagriculturalrevolution,34

allelomimeticbehavior,63,74-75

behaviorpatterns,63-65,383-84

behavioralsystems,61-80

comparisonwithhuman,80-83

comparisonwithhuman,80-83

breedingcycle,67,279

caredependencyrelationship,174

chromosomenumber,53

classification,29-31

criticalperiodforprimarysocialization,

117-50developmentofbehavior,84-116developmentofsocialrelationshipsin,

151-82domesticationfromwolf,54-56dominance-subordinationrelationship

in,77effectofhumanculturalchangeupon,

432-33effectofisolationupongeneticchange,

398-99inEgypt,34

eliminativebehavior,65,68-70epimeleticbehavior,63,70-71,169-

75et-epimeleticbehavior,63,72evolution,81-82,397-411,433geneticvariation,4,400-401

indevelopment,418

magnitude,358-66geographicaldistribution,31-32growthandgrowthcurves,326-32humansocialneedsfor,432huntingbehavior,75-76,78-80hybridswithothercanids,52-53ingcstivebehavior,60,65,72-73investigativebehavior,63,78-80inIraq,34inJanno,34inJericho,34-35leader-followerrelationship,175maternalbehavior,169-75inMesopotamia,34-35mother-offspringrelationship,169-75mutationsin,51origin,29-56

evidencefrompre-history,33-36

evidencefromtaxonomy,30-33

fossil(\idence,33

inPalestine,performancetestscomparedwithhuman[Qtests,257periodsof

inPalestine,performancetestscomparedwithhuman[Qtests,257periodsofdevelopment,84112aspilotexperimentforhumanrace,397

polymorphismin,83

serologicalrelationshipwithothercanids,44-45

sex-linkedinheritancenotfound,283

sexualbehavior,62-68

shelter-seekingbehavior,65.73-74

skullshape,38-44

socialbehavior,57-83

socialgroups,61-62,414—15

socialorganizationin,414-29

socialrelationships,153

socializationin,118-41

somatotyping,339^3

specializationin,402-3

stoneage,34-35

territory,62,69,110

useinbehaviorgenetics,325

variationintoothsize,39,41

"wild,"30Dogbreeding,383-96

environmentalcontrolin,384

geneticmanagement,390-91

history,399

hybridizationin,392-93

methodsforassociations,393-91

methodsforkennelowners,393

forphysicaltype,389

forresearch,394-96

selectionmethods,391-92

strainimprovement,391-96

andstructuraldefects,389-90

seealsoRearingpracticesDog-humancomparison,ofheritabilities,

324Dog-humansocialrelationship

development,175-80

noveltyin,415-16

optimumtimeforinitiating,385Domestication

estimateddateandlocation,54-56

effectsondog,400-3Dominance,genetic,effectsonbehavior.

35&-5SDominanceorganizationofgroup,genetic

effectsupon,163-64Dominance-subordinationrelationship


development,155-69

dog,77,154,415

<ffectofgeneticsegregationupon,165-66

effectofheredityon,418-19

effectofsexon,16I

effectofsi/eon,164-65

effectonexpressionof"jealousy,"167

effectonfighting,156-59

injuvenileperiod,109-10betweenmothersandoffspring,175wolf,77,415

Dominancetest

breedcomparisonsofbarking,274-75breedandhybridcomparisons,360measureofaggressiveness,137methods,155-56intestschedule,18-19,24

Drinking;secIngestivebehavior

Duck,socializationin,143

Dwarfbreeds,brainsize,42

Dwarfpinscher,skullmeasurements,4041

EEG,development,93,107Ear,firstfunctionof,94Earlyexperience

dogdevelopmentsuitableforexperiments,112-13EastIndies,dogsin,54Eating;secIngestivebehaviorEcologicalniche,wolfandhuman,397Ecology,Canis,31Egypt,dogsin,34,54Eliminativebehavior

inemotionalreactivitytest,202


inneonatalperiod,85

patternsindog,65,68-70

patternsinwolf,65,68-70

patternsinwolf,65,68-70


intransitionperiod,91Emotionalbehavior

effectofgeneticson,6

effectonmazeperformanceinrats,6

effectonperformance,246-47,256,387

effectsontrainability,222

importanceinselectionforperformance,387,394Emotionalreactivity

definition,194

heritabilityof,204

Pavloviantypesof,195

sexdifferencesin,202

unitarynatureof,203,315-16EmotionalreactivityfactorinFihybrids,

374Emotionalreactivitytest

agechangesin,198-201,312-13,315

bitingin,313-14

bodypositionin,313



SUBJECTINDEX457

effectofheredityatdifferentages,201

effectofmaternalenvironment,285


heartrate,199,313-14

hybridcomparisons,inheritance,312-17

loadingsinactivity-successandheat-ratefactors,372

loadinginreactivityfactor,374

matingdifferences,316-17

methods,194-97

observerreliability,196

responsecategories,196-97

resultsinhome-reareddogs,180

resultsin"wilddogexperiment,"128

tail-waggingin,313-15

intestschedule,21-22,24

variancecomponents,360,366Emotionalresponse,effectofconditioning

upon,100Emotionaltests

factoranalysisof,369-70

variancecomponents,360Endocrineglands,differencesamong

breeds,6England

developmentofdogbreedsin,4548

dogsof,432

firstdogshow,399Englishsetter,hemophiliain,407Environment

effectofvariationonbehavior,236,256

effectofvariationonbehavior,236,256

enrichedeffectsondogsandrats,26-27

physical,25-28

variancecomponents,190Environmentalimprovement,useindog

breeding,384Epimeleticbehavior

dog,63,70-71

selfgrooming,107

wolf,63,71Eskimodog

comparedtowolf,403

resultofadaptiveradiation,398Et-epimeleticbehavior

dog,63,72

inneonatalperiod,85


intransitionperiod,91-92

wolf,63,72Eurasia

aboriginaldogbreedsin,399

distributionofjackalin,31

wolfin,31Europe,dogsof,432

SUBJECTINDEX

involution

behavioraconservativetraitin,415dog,397-411human,399-400,409-12Evolution,cultural

comparedtobiologicalevolution,430-

31effectonbiologicalchange,429-33synergisticrelationshipwithbiologicalvariation,431-33Evolutionofbehavior,dogandhuman,

81-82Experimentaldesign;seeMethodsEye

developmentinsocializationperiod,

107developmentintransitionperiod,93-

94inheritanceofdefects,389-90timeofopening;inbreedsandhvbrids,89-90

Factoranalysis

breedandhybridpopulations,371-75

emotionalandphysiologicaltests,369-70

evidenceofgeneraltraits,367-68

andgenetics,343-44,368-99,376

performancetests,370-71

physique,340,343^4,347-51Failure,effectonmotivation,230-31,256Fearofapparatus

inspatialorientationtest,320

intrailingtest,246-47,256Fearresponses


development,104-5

seealsoAgonisticbehaviorFeeblemindedness,correlatedwithlow

fecundity,410Fennec,chromosomenumber,53Fertility

declinewithage,110

increaseunderdomestication,401-2

probleminhumanpopulations,410Fighting

effectofdominancerelationshipupon,156-59

seealsoAgonisticbehavior;Dominance-subordinationrelationshipFighting,playful

developmentof,105-6

effectonsocializationindog,130

inheritance,269-73Followingtest

breedcomparisons,174-75,177

methods,173-74Foodandfeeding,11-12,14Foodrewards,effectondog-humanrelationship,177-78Forcedtraining,205-16


non-unitarynatureofreactions,215-16Fossils,fromCanidae,33Fox

chromosomenumbers,53

comparedtowolf,403

fossils,33

serologicalrelationshipwithothercan-ids,4^-45

socialbehaviorpatterns,62-65

socialgroups,414-15Foxterrier

clubfootin,390

earlylearningin,97-9S

groupattacksby,106

history,50

rateofdevelopment,418

reactiontopunishment,145

sizefactorin,349


useofsenses,80

weightgain,327

seealsoBreedcomparisonsFrance,dogsof,432

Geneaction,theoryofspecific,333-34Geneticeffectsonbehavior,3-7Geneticequilibrium,theoryof,407-8Geneticvariation,indevelopmentofdog

andhuman,418Genetics

anddifferentiationofbehavior,165-69.181

andfactoranalysis,367-69.376

ofgenusCanis,51-53

sub-divisions,413Geographicaldistribution,dogandother

Canidae,31^32Germanshepherd

fewcorrelationsofphysiqueandbehavior,350

hipdysplasiain,407

jawshape,39

skullmeasurements,40-42Goal-orientationtest




methods.217

variancecomponents,361(loldenretriever,history,50

Goose,primarysocializationin,142Greatdane

agonisticbehavior,7S

jawshape,39

size,56,400-401

skullmeasurements,40-42Greyhound

comparedtowolf,402

history,45-47,51

jawshape,38

leglength,29

origin,399

skull,400

skullmeasurements,40—43Growth

dog,326-32


modelforlearningprocess,332,352-53

relationtoperiodsofdevelopment,326-29Growthcurves,dog,328-31Guarddog,Kurdish,34Guineapig

criticalperiodin,143

polydactylousmonster,333

Habitformation

effectofheredity,425limitsvariabilityofbehavior,151weaktendencyinbeagle,237-38Habit-formationtest;seeGoal-orientation

testHaircolor,inheritanceandrelationto

behavior,338-39Ilairlength

inheritance,262,334-36inrelationtosizeandbehavior,336-37Handlingtest

breedcomparisons,134-38correlationwithtrailingtest,374developmentalchanges,176-77effectsofhandfeedingupon,177-78effectofmaternalenvironment,284-85ofhome-reareddogs,179-80inheritance

offearreactions,267-68ofplayfulaggressiveness,269-73loadingin

activity-successandheart-ratefactors,372reactivityfactor,374methodsresultsin"wilddogexperiment,"125

SUBJECTINDEX459

intestschedule,18,24variancecomponents,360,366Handler,effectonobediencetest,212.

214Hardy-Weinberglaw,404-5Heartrate

changeswithage,199effectofmaternalenvironment,285inheritance,287inreactivitytest,199,313-14relationtoarrhythmia,203responsetoquieting,199variancecomponents,360,366Heart-ratedevelopment,breedcomparisons,121-22Heart-ratefactor,ofphysiologicaltests,

372-73Hepatitis,infectiouscanine,controlof,

15Hemophilia

inEnglishsetter,407inheritance,389Heredity

actionthroughdevelopmentalprocesses,113culturalandbiologicalcompared,430-

31effects

31effects

ofculturalevolutionupon.431-33ondevelopmentofsocialrelationships,421-24ondifferentiationofbehavior,152ondominanceorganizationofgroup.

163-64onlearningcapacities,424-25,428-

29onsocialrelationships,113,418-10onsocializationprocess,133-41ontrainability,222-23onvariationandhabitformation,425magnitudeofeffectonbehaviorand

physique,358-66synergisticrelationshipwithcultural

evolution,431-33variancecomponents,190,321Heritability

ofbehavior,andselection,391-92effectofpracticeon,254-56emotionalreactivitytest,201,316leashtrainingtest,299,301,305limitationsandusefulness,324-25measuredbyintraclasscorrelation,192methodsofestimation,185-86motivationtest,308obediencetest,311

460SUBJECTINDEX

problemsolvingbehavior,321,388

jrcssionanalysis,297-98specificityofestimates,323-25summarytable,360-61Hernia,inguinal,inbasenji,389,406Heterogeneitv,inpurebreeds,185,295,

7,386-87Heterosis;seeHybridsuperiorityHipdysplasia

inGermanshepherds,407inheritance,359,391History,dogbreeds,45-51Home-reareddogs,socialrelationships,

17&-82Homozygosity,rareinpurebreeds,378Hostility,towardsimilarandunlikedogs,

167-68Hounds,agonisticbehavior,77Housebreaking,behaviorpatternsuseful

in,102Housing

designofnurseryroomandruns.25-

"26planforall-weatherkennel,27Humanbehavioralsystems,80-83critical

"26planforall-weatherkennel,27Humanbehavioralsystems,80-83criticalperiodininfant,147-50dangerfrommutations,408-9developmentofsocialorganization,

417ecologicalniche,397effectof

assortivematinson,428isolationupondevelopmentof.147-48ivolution,81-82,399-400,409-12fertility-andsterilityproblems,410geneticchangein,399^00

triationindevelopment,41BIQtestscomparedwithdogtests,257periodsofdevelopmentin,113-16ymorphism,usefulnessof,83,411-'12prenatalmirtalityrate,410sociali.(■•dsfordoes,432somatotyping,339-40variation.401Hunting,behaviorpatternsindogand

wolf"

Huntingdiicalrecords,45-4S

Hybridcomparis

08-9n\la\t.309-10

tartlcresp•'tfvity,315lotionoft

leashtraining,299-306

mortalityrates,405-6

motivationtest,307-8

motordevelopment,96


obediencetest,311

physiqueandbehavior,345-46

spatial-orientationtest,318-20

statisticalmethods,297-98

summary,360-61

timeofopeningofeye,89-90

variancecomponents,360-66

seealsoInheritanceHvbridization,indogbreeding,392-93.

396Hybridsuperiority

inbasenji-cockerci



inspatialorientation.31vHybrids

behaviorof,295-325


reactivityfactorinFi,374

forresearch,395

betweenspeciesingenusCants,52-53Hydrocephaly,incockerspaniel,390

Icelandicdog,skullmeasurements,40-41Imprinting

equivalenttoprimarysocialization,142ohoSocialization,primary;Socialization,period;Socialization,processInbreeding,infoundationstock,48-49Individualvariation

indelaved-re^:.243-4I

310inemotionalreactivity,202inmazetest,237inspatial-orientationtest,251variancecomponentswithinlitters,190-91.321,364-67[ngestrvebehaviordog.60.85,72effectonm131,

144-46insocializationperiod,101intransitionperiodswolf,65,72-7Inheritance,modeof

ianccandvocalizationpatl267-6S

ingandbarkl<aviorpatterns.261-94bod)

SUBJECTINDEX

461

emotionalreactivitytestscores,312-

17haircolor,338hairlength,262,334-36heartrate,287leashfighting,268-69multiple-andsingle-factortheories,

367-68noclearpatternsinperformancetests,

367-68noclearpatternsinperformancetests,

285-86patternsofagonisticbehavior,267-78playfulfighting,269-73posturalresponses,288-92quietingtest,287-88selectionand,392structuraldefects,389-90wildnessandtameness,266-69seealso,Single-factorinheritance;PolygenicinheritanceInsightlearning,developmentindetour

test,228-29,256Instinct,inrelationtobehaviorpatterns

andsystems,60"Intelligence"concept

noevidenceofgeneralfactor,256,388,

427seealsoProblem-solvingbehaviorIntelligencetests;seeTest;Performance

testInteraction,genotype-lifehistory,325Intraclasscorrelation,measureofherit-

ability,definition,192Investigativebehavior

breedcomparisons,137-38indogandwolf,63,78-80effectonsocializationindog,130inemotionalreactivitytest,200inneonatalperiod,85insocializationperiod,104intransitionperiod,91Iraq,dogin,34Irishwolfhound,skullmeasurements,40-

41Isolation

effectsonsocializationprocessandhumandevelopment,145-48andgeneticchangeindogs,398-99

Jackal

appearanceandsize,37

chromosomenumber,53

classification,31

distributioninAfrica,Eurasia,31

fossils,33

hybrids,52-53

serologicalrelationshipswithothercanids,45

skullmeasurements40-41,44

socialgroups,415

vocalization,50Jackdaw,socializationin,142Jarmo,dogin,34

Jawshape,ofdogsandwolves,38-41"Jealousy,"inrelationtodominance-subordinationrelationships,167Jericho,dogin,34-35,54Juvenileperiod,dog,108-10

KasperHauser,caseofpartialisolation,

147-48KingCharlesspaniel,history,46

Labradorretriever,history,50

Laplanddog,skullmeasurements,40-41

Leader-followerrelationship,dog,154

indogandwolf,175,415Learning

analogywithgrowth,332,352-53

basicprocessofculturalchange,424,430

complexinteractionwithheredity,426-28

effectofheredityupon,424-25,428-29

effectsonexpressionofgeneticvariation,425-26

effectsonsocializationprocess,144

limitingfactoronbehavioralvariation,428

seealso;Training;PerformanceLearningcapacities


inneonatalperiod,87-88,98


intransitionperiod,97-100Learningcurves,mazetest,235Leash-controltest;seeLeash-trainingtestLeashfighting

inheritanceof,268-69

inleash-trainingtest,301-5Leash-trainingtest


demeritscoresinhybrids,299-300


heritability,299,301,305


inheritanceofleashfighting,268-69

intercorrelationsofdemerits,210

loadingsonreactivityfactor,374

methods,207

SUBJECTINDEX

resultsin"wilddogexperiment,"127-2fl

intestschedule,22.24

variancecomponents,361-62,366Legs,mutationforshortness,42Levelsoforganization,inrelationtobehavior,5Lip-licking,inemotionalreactivitytest.

199Litterdifferences

incue-responsetest,242,309

inemotionalreactivity,203

inleash-controltest,301-2

proportionofvarianceassociatedwith,190-91,364-67

inspatial-orientationtest,319Localization,processof,102—4,112

Mammals,socializationin,143-44

Man;seeHuman

Manchesterterrier,chromosomenumber,

53Manipulationtest

breedcomparisons,230-31,361correlationwithtrailingtest,374hybridcomparisons,361loadinginactivitv-successfactor,372method,229-30Mastiff

agonisticbehavior."9history,46Masterlistofexperimentalanimals,10Maternalbehaviordog,169-75.151limitsperiodofsocializationinsheep,

L30weaningtest,173seealsoEpimeleticbehaviorMaternalenvironment

effectsontests.283-85,363onleashtraining,300-301onreactivitytest.317Matings,differencesbetweenanalysisofvariance,29Sincue-responsetest,309inleash-controltest.302-5inreactivityte>t.316-17

inceassociatedwith,190-91,364-66Maturation,interactswithgeneticdiffer-

er.Mazeperformance,rats,effectofemotionalbehavior,6Maz-

behaviordur

Icomparison,234-3"_

correlationwithtrailingtest.374

loadinginactivity-successfactor.172

methods,232-34'

and"positionalhabit"factor,370

variancecomponents,236-37,361Mendeliangenetics,413Merlegene,geneticmanagement,390Mesopotamia,dogin,34,35

domesticationofdogsin,54Methods

analvsis

of'qualitativeinheritance,264-66ofsingle-factorinheritance.262-66ofvariance,159-93,236

breedingplans,7-11

correlational,appliedtogeneticvariance,376-78

cue-responsetest,238-42

delaved-responsetest.242

detourtest,19-20,226-17

diseasecontrol,13-15

dominancetest,155-56

emotionalreactivitvtest,194-97

followingtest,173^74

genetic,7-11,296-97

goal-orientationtest216-17

handlingtest,133-34

leash-trainingtest.207

manipulationtest.229-30

maternalretrievingtest,171

mazetest.232-34

motivationtest.240


nutrition,11-12

obediencetest.211-12

observationofbehaviorpatterns.r"58

observationofdevelopment,15-17

performancetests.19-25

physiquemeasures,340-41

quietingtest.206

retrievingtest.2IS

sanitation.13-14

ofscalinc

socialbehaviortests.17-19

spatialorientation,248-50

statistical

breedcomparisons.1^5-93hvbridcomparisons,297-98

trailingtest,244-45

variancecomponentcomputation,359

weaningtest,173Mexicanhairless.29.400MiddleEast,d\

mentonbreeddifferences,191Moleculargenetics,413

SUBJECTINDEX

463

Molossianhound,56

Monorchidism,inShetlandsheepdog,390

Mortalityrates

breedandhybridcomparisons,405-6

humanprenatal,410Mother-offspringrelationship,dog,169-

75Motivation

breedcomparisons,3S7

effect

offailureon,230-31,256onperformance,3S7-SS,428-29onproblem-solving,230-31methodusedinperformancetests,20-21Motivationtest

breedcomparisons,240

effectofmaternalenvironment,2S5


method,240

staninescaling,188-S9Motorcapacities

injuvenileperiod,108-9

inneonatalperiod,87

insocializationperiod,107Motordevelopment

breedandhybridcomparisons,96

breedandhybridcomparisons,96

Intransitionperiod,94-96Motor-skilltest



hybridperformanceon,221-22

loadinginactivity-successfactor,372

methods,219-20

intestschedule,22,24

variancecomponents,361Multiple-factorinheritance;seePolygenic

inheritanceMutations

accumulationindogs,405-8

basisofvariationindog,51-52

dangerinhumanpopulations,408-9Mutualcarerelationship,indog,154Mutualdefencerelationship,dog,154Myelination,inneonatalperiod,88

Naturalselection

anddegeneration,404,408

roleinhumanpopulations,403,410Neonatalperiod

characterizedbyneonatalnutrition,416

declineofnursingin,170-71

dog,84-89

rearingpracticesfor,384

Newfoundlandbreed,skullmeasurements,40-41"Nicking,"useindogbreeding,392-93NorthAmerica

breeding,392-93NorthAmerica

distributionofcoyotein,31

dogsin,55

stoneagedogsin,35

wolvesin,31Norwegianharehound,skullmeasurements,40-41Nursingbehavior,170-71Nutrition,methodsof,11-12

Obediencetest

breedcomparisons,213-14hybridcomparison,311loadingsinactivity-successandheart-ratefactors,372methods,211-12intestschedule,22,24variancecomponents,361Obesity,inShetlandsheepdog,390,406Observerreliability,inemotionalreactivitytest,196Olfaction,inneonatalperiod,86"One-mandog,"lackofevidencefor,

213-14;223Organizationofbasiccapacities,intraining,222Otocephaly,inbeagle,390Outbreeding,protectsrecessivegenes,405

Palestine,dogin,34Panmixis

effectondogbreeds,399

human,400Parent-offspringcorrelation;seeRegressionanalysisPassive-handlertest

reactionofbasenjis,145

resultsin"wilddogexperiment,"125-26Pekingese,skullmeasurements,40-42Performance,effectsofemotionaland

motivationaldifferences,387-88Performancetests



ofhome-reareddogs,180

loadingsinactivity-successfactor,372-73

methodsof,19-25

motivationin,20-21

noclearpatternsofinheritance,285-86

SUBJECTINDEX

relationshipsbetween,21

scheduleoftesting,22-24Periodsofdevelopment

dog,84-116

andgrowth,326-29

human,113-16

andproblem-solving,224

processesof,416Persistencetest;seeSpatial-orientation

test"Personality"

andbehavioralorganization,80

expressedassocialrelationships,166-67,419-20Physiology,comparative,evidenceondog

origin,44^45Physiologicalgenetics,413Physiologicaltests


heart-ratefactor,372-73Physique

andbehavior,breedandhybridcomparisons,344-47

factoranalysis,346-51

generalsizefactor,348-49,371

generalsizefactor,348-49,371

magnitudeofgeneticeffectson,358-66

methodsofmeasurement,340-41

relationtobehavior,326,333-55,389

variancecomponents,360,362,366Pleiotropy

inbehavior,375

hypothesesconcerning,333,371

limitedoccurrenceof,352

andtypeconcept,353-54Pointers


comparedtowolf,403

history,48

skullmeasurements,40-41Polydactyly,guineapig,333Polygenicinheritance

ofbehaviorpatterns,293

expressionof,262-63

theory,367-68Polymorphism

indogs,wolves,humans,83

usefulinhumansocieties,411-12

wolf,398Poodle

hairlength,29

hairstructure,400

skullmeasurements,40-41Populationconcept

skullmeasurements,40-41Populationconcept

appliedtodogbreeds,393

appliedtodogskeletons,37-44

appliedtohumanpopulations,354-55

ofspecies,30

useintaxonomyandgenetics,351-52Populationgenetics,413-14Populations,wolf,variationin,43Posturalresponses,inheritance,288-92Practice,effectonheritability,254-56Predation;seeHuntingPrehistory,evidenceofdogorigin,33-36Problem-solvingbehavior,224-58

asadaptation,388


dog-humancomparison,257

dualprocesstheoryof,322-23

heritabilityof,321,361,388

motivationand,255,320-21

unitarynatureof,256-57,388-89Problem-solvingtests

scheduleoftesting,22-24

varianceofcomponents,361Processes,ofdevelopment,111-12Psychologicalprocesses,insocialrelationships,151-52Pug

headshape,29

skullmeasurements,40^2Punishment,effectonsocializationprocess,145-46

Qualitativeinheritance,methodofanalysis,264-66Quantitativeinheritance,methodofanalysis,263-64Quietingtest

breedcomparisons,206-7,360

differentiationofbehaviorin,425-26

hybridcomparisons,360

inheritance,287-88


loadinginreactivityfactor,374

method,206

Raccoondog,chromosomenumber,53Raceconcept,inrelationtotypeand

populationconcepts,354-55Races,notequivalenttodogbreeds,82Radiation,effectsonmutation,409Rat

effectofenrichedenvironment,26-27

cflcctsofgeneticsonbehaviorof,5-6

Rattlepinscher,skullmeasurements,40-

41Reactivitytest;secEmotionalreactivity

testRearingpractices,384-87Regressionanalysis

SUBJECTINDEX

465

ofheritability,297-98

ofleash-controlscores,305

ofmotivationtest,30S

ofobediencetest,311Reliability

leash-trainingtest,207

obediencetest.213

obediencetest.213

tial-orientationtest,254-55rch,useofpurebreedsandhvbridsin.394-96Retric-

agonisticbehavior,7S

useofsenses,79Retrievingtest

breedcomparisons,219

criticalperiod.II

methods.218

intestschedule,22.24Retrievingtest(maternal)

breedcomparisons.172-73

method,171Rewardtraining,216-23

asmethodofsocialcontrol,155Rhesusmonkey


effectofrearinginisolation,145Russia,stoneagedogin,35

SaintBernard

jawshape,38,39

size,400

skullmeasurements,40-42

weight,29Saluki

gazellehuntin:

history,51

leglength,29

skullshape.42

useinMiddleEast.

useofsenses,79Sanitation,methodsof,13-14Scaling

methodsof,324

staninesystem,186-89Scheduleoftesting,24Schnauzer,skullmeasurements,40—41Scottishterriers,useofsenses,80Sealvhamterriers,chromosomenumber,

53Segregation,genetic

effectonvariance,357-58

evidencefor,355-58Selection,effectlimitedbyheritability,

391Selectionprocedures,indogbreeding,391-92,396

Sensorycapacities

inneonatalperiod,S6-S7

useinhunting.79Separation,effectsuponsocialization

process,149-50Serologicalrelationships,betweencanidae,

"44-A5Setters

agonisticbehavior.

comparedtowolf,403

history,46

skullmeasurements,40-41Sexdifferences

effectondominance-subordinationrelationship,164-65,419

growthcurves,329-32

noneinemotionalreactivity,202-3Sex-linkedinheritance,2S3

notfoundindata,362Sexualbehavior

dog,62-6S

effectonsocializationindog,130-31

effectonsocializationinsheep,129

home-reareddogs,179

inheritanceofbreedingcycle,278-83



wolf,62-68Sexualrelationship,dog,154Sheep


developmentofflockorganization,417

effectofhumansocializationupon,129-30Sheepdogs


comparedtowolf,403Sheepdogs;seeShedandsheepdogShelter-seekingbehavior

dog,65,73-74

intransitionperiod,92

wolf,65,73-74Sheltie;seeShedandsheepdogShetlandsheepdog

earlylearningin,97

history,50

managementofmerlegenein,390

managementofmerlegenein,390

obesityandmonorchidismin,390

readyhabitformationin,425

sizefactorin,349


stereotypedbehaviorin,237

seealsoBreedcomparisonSingle-factorinheritance,367-68

behaviorpatterns,292-93

methodsofanalysis,262-66

Size

breedandsexdifferences,329-32

correlationwithbehavior,344-51

effectondominance-subordinationrelationship,164-65

inrelationtohairlength,337

variationindog,401Skeleton

dog,37-44

wolf,51Skullmeasurements,wolf,40-41,51Skullshape,ofdogs,wolves,andother

canids,38-44Smell,senseof;seeOlfactionSocialbehaviorpatterns

changesintransitionperiod,89-93

coyote,62-65

dog,57-83

fox,62-65

methodsofmeasuring,17-19

inneonatalperiod,84-86


wolf,57-83Socialcontrol,indog-humanrelationship,

154-55Socialdevelopment,correlatedwithsocialorganization,416-17Socialenvironment,experimentaldesign,

17-18Socialgenetics,subjectmatter,413-33Socialgroups,61-62Socialorganization

incaninesocieties,414-29

correlatedwithsocialdevelopment,416-17

stabilizingeffectongeneticchange,429-30Socialrelationships

classification,152-53

definition,151

developmentindog,151-82,416

differentiationofbehaviorin,152,416

dogandhuman,152-53

effectofheredityupondevelopment,113,421-24

expressionof"personality"in,166-67,419-20

psychologicalprocessesin,151-52Socialrelationship,tests

scheduleof,18-19

variancecomponents,360Socialization,dog-human,optimumtime

for,385Socialization,primary

inants,141-42

inbees,142

inbirds,142-43

indogs,118-41

inmammals,143-44Socializationperiod

characterizedbydevelopmentofsocialrelationships,416

dog,101-8

rearingpracticesin,385

variationinboundaries,120-22Socializationprocess

analysisof,144-47

behavioralmechanisms,129-33

effectsofadoptionupon,149

effectsofgeneticdifferences,133-41

effectsofseparationupon,149-50

largelyindependentofoutsidestimuli,146-47Somatotype

indogandhuman,339-43

evaluationofconcept,351Songsparrow

rapiddevelopmentin,115

socializationin,143Spain,originofspanielin,46Spaniels

chromosomenumber,53

comparedtowolf,403

history,45-48

seealsoCockerspanielSpatial-orientationtest




fearofapparatusin,320

geneticvarianceconstantin,426



methods,248-50

persistencein,250

reliabilityof,254-55

intestschedule,23-24

thresholdeffect,320

timeanderrorsin,251,253-254

variancecomponents,361Specialization

effectofdomesticationupon,402-3

imposeslimitsonadaptation,427-28Species,populationandtypeconcepts

of,30Sport,historicalrecords,45-48Springerspaniel

earlylearningin,97

history,48Staninescalingsvstem,descriptionandprocedure,186-89

SUBJECTINDEX

467

Startleresponse,breedandhybridcomparisonsofdevelopment,94Stereotypedbehavior,inmazetest,237Sterility,inhumanpopulations,410Stoneagedogs

geographicaldistribution,34-35

skullshape,37-38Strainselection,effectofaccidental,283-

84Suckling,effectofsuddenweaningon,90Sucklingbehavior

inneonatalperiod,85

intransitionperiod,89-90"Superman"myth,403,411

T-mazetestapparatus,239

commonvariancewithtrailingtest,377correlationwithtrailingtest,374loadinginactivity-successandheart-ratefactors,372loadinginreactivityfactor,374and"positionalhabitfactor,"370intestschedule,23-24variancecomponents,361,366SeealsoCue-response,motivation,anddelayed-responsetestsTail-wagging


inemotionalreactivitytest,202,313-

15equivalenttosmile,104Tameness,inheritanceof,266-69Taxonomy,evidenceofdogoriginfrom,

30-33Teeth

eruptionoffirstcaninesandincisors,

95-96eruptionofpermanentteeth,108sizevariationindogs,39,41Temperature,controlandrecordingof,

26Terriers

26Terriers

agonisticbehavior,77comparedtowolf,402-3history,46-47seealsoFoxterrierTerritory

dog,62,69,110wolf,61,69,76Test

effectsofmaternalenvironmenton,

283-85seealsoScheduleoftesting,24,andundernameofspecifictest;seealso;Emotionaltests;Performance

tests;Physiologicaltests;Physique,Problem-solvingtests;Socialrelationship;TrainingtestsThresholdeffects

inemotionalreactivitytest,314inspatialorientation,320Timidity,independentofaggressiveness,

369-70Timidityfactor,375-77Trailingtest

breedcomparisons,246-47commonvariancewithT-mazetest,377correlationwithperformancetests,374effectofmaternalenvironment,285fearofapparatusin,246-47loadinginactivity-successfactor,372method,244-45intestschedule,22,24variancecomponents,361,366Trainability,205-23Trainabilitytests,variancecomponents,

360-61Training

effectongeneticvariance,210-11,

213,222-23,254-55effectonobediencetest,213asformofproblem-solving,225Training,forced,reducesexpressionof

geneticvariation,425Traitconcept,inadequacy,427Traits,littlegeneralityof,323-24,375,

378Transitionperiod

characterizedbydevelopmentofadult

behaviorpatterns,416dog,89-101

rearingpracticesfor,385variationinboundaries,120"Tryondistribution,"264,266,270-73,

280-82"Type,"resultofselectionfor,393-94"Type"concept

appliedtobehavior,371

andemotionalreactivity,195

inadequacyof,351-52

littleevidenceforbehavioral"types,"

427relatedtopleiotropy,353-54inrelationtoraceconcept,354-55ofspecies,30useandabuseindogbreeding,389

Undershotjaw

inbasenji,406

inheritance,389UnitedStates,dogsof,432

SUBJECTINDEX

Variance

betweenbreeds,185,190-91,295effectoftrainingongenetic,210-11,

213,254-55proportionattributedtomatings,litters,andindividuals,364-67insegregatingandnon-segregatingpopulations,357-58Variancecomponents

breedandhybridcomparisons,360-67inmazetest,236-37methodofcomputing,359theoreticalanalysis,190-91Variation

extentinformandbehaviorofdog,4,

400-401useindogbreeding,396Visualclifftest,93-94Vocalization

developmentofreactiontostrangepen,

102înemotionalreactivitytest,202inleashtrainingtest,305-6onscale,breedcomparisons,92onscale,loadinginheart-ratefactor,

comparisons,92onscale,loadinginheart-ratefactor,

372onscale,loadinginreactivityfactor,

374onscale,variancecomponents,360instrangeroombybeagles,122

Walking,timeofdevelopment,95Weaning

effectonnon-nutritivesucking,90

processof,101Weaningtest,method,173Weight,gainperweekinpuppies,327Whippet,skullmeasurements,40-41"Wilddogexperiment,"oncriticalperiod

hypothesis,124-29Wildness

development,105

effectofdomesticationupon,402

inheritanceof,266-69

Wire-hairedfoxterrier;seeFoxterrier

Wolf

agonisticbehavior,64,75-78allelomimeticbehavior,63,74-75appearanceandproportions,36-37behaviorpatterns,63-65,383-84behavioralsystems,61-80breedingcycle,278classification,29,31

developmentofpackorganization,416domesticationofdogfrom,54-56dominance-subordinationrelationship

in,77ecologicalniche,397eliminativebehavior,65,68-70epimeleticbehavior,63,70-71et-epimeleticbehavior,63,72fossils,33

huntingbehavior,75-76,78-80hybrids,52-53

Indian,asancestorofdogs,38ingestivebehavior,65,72-73investigativebehavior,63,78-80leader-followerrelationship,175inNorthAmerica,Eurasia,31polymorphism,83,398relationshiptomodemdogbreeds,433resultsofhumansocialization,140-41serologicalrelationshipwithotherca-

humansocialization,140-41serologicalrelationshipwithotherca-

nids,45sexualbehavior,62-68shelter-seekingbehavior,65,73-74skeleton,51skullshapeandmeasurements,38-41,

43,51socialbehavior,57-83socialgroups,61-62,414-15territory,61,69,76

unspecializedcomparedtodog,402-3variationinpopulations,43,51

"Wolfchildren,"148-49

Workingdogs,breedingof,394

Worms,intestinal,controlof,13

Documents

Genetics and the Social Behavior of the Dog - gwern · 2019-03-11 · genetics and schizophrenia. A committee on behavior genetics has been set up by the Social Science Research Council