Ales Hrdlicka 1940

8/2/2019 Ales Hrdlicka 1940

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LOWER JAWI. THE GONIAL ANGLE

11. THE BIGONIAL BREADTH

ALES H R D L I ~ X AU. 8.Nationul Xuseum, Smit l i sonian Inst i tu t ion , Washington, D . C.I. TH E GONIAL ANGLE

lorok, in 1898, called the lower jaw tlie neglected stepchildof anthropometry, and while numerous contributions to thestudy of the bone have been made since, a large majorityof these were so small that to some extent the reproach isstill applicable today. The reasons fo r this remissness wereand still are the concentration of attention in craniology onthe vault and on the upper face; inadequate and often damagedo r otherwise unsatisfactory materials ; difficulties presented tothe student by the extensive variations of the bone, withimperfect landmarks ; and its seemingly secondary interestin the anthropology of recent human groups.

As a matter of fact the human lower jaw-I do not like theterm mandible for the human bone-is both phylogeneti-cally and ontogenetically one of the most interesting parts ofthe human skeleton. A separate loose bone, an appendaget o the rest of the face, it yet possesses a rich evolutionaryand in modern times also involutionary history, shows astonish-ing correlation with the maxilla, the rest of the face and thebase of the skull, presents unique age changes, and differscharacteristically in the two sexes. It carries o r reproducesnow and then long past ancestral features, and is capable ofremarkable functional adaptations. The more attention itreceives the more evident it becomes that its whole statusdeserves well to be restudied and established.

281


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282 ALEB HRDLIEKA

A good example of this need is shown by the item which isthe subject of this paper, the body-ramus, o r simply the gonial,angle. This feature has been taken here because it constitutesa definite morphological unit, offers valuable group, age, sexand other variations, and is one of the easiest to measurefairly accurately by different observers.

The gonial angle is the postero-inferior angle of the bone,formed by the ramus with the body. This separation of thetwo portions of the jaw under different names is howeveranatomically incorrect. It gives the impression of two dis-tinct parts, which is wrong. The old terms of horizontal andascending portions were much better. The bone develops intwo halves, the right and left, and there is but one center ofossification for each half with its ramus. The latter is nota branch at all, but merely the ascending part of each halfof the jaw.

The membrane in which the bone develops overlies in theembryo the MeckeIs cartilage, an almost straight band whichconstitutes the first mandibular arch. I n this there is as yet nobend upward of the posterior part, no ramus; it approachesthe condition of the jaw in the reptilian forms. The bend orangle appears first in the bony jaw, but even here for a timeit is generally but mild, approaching such form as seen in thepinnipedians. Even at birth the gonial angle is still veryobtuse, mostly above 140 or even 150 degrees. As teethdevelop and separate the jaws, the angle grows less, untilin extreme cases it may reach 100 degrees o r even slightlylower; but in these cases the angular par t of the posteriorborder of the ascending branch is overdeveloped.

I n looking over the mandibles of the vertebrates below man,there is found much of interest as t o the angle. Thus in fishes,turtles and saurians there is no ascending branch and noangle, and similarly in birds. In the long-tailed Pangolin,and in the anteaters, the jaw is near horizontal, and there isno ramus or angle, o r only bare indications of the same.In the fur-seal the lower jaw is still near horizontal ormoderately curved, without distinct ascending branch or angle,and in the sea-lion is not much farther in these respects; but


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L O W E R JAW 283in the Indian seal there is already a fairly distinct ramusand a marked angle. I n general and though the ramus may insome species be decidedly underdeveloped, a marked gonialangle is present in all terrestrial mammals. I n most of theungulates the ascending part is largely developed and high,and the angle region is broad, its margin approaching semi-circular. I n all the carnivora, rodents and primates, and inrelated genera, both the ascending part and the angle, thoughvarying, are well developed ;and in the two largest anthropoidapes, the gorilla and the orang, the ramus is huge, thoughin its conformation and in the near-semicircular outline ofits angle region it still resembles that of some of the largelower vertebrates more than it does human. But in the Oldas well as the New World monkeys, in the gibbons, and inthe chimpanzees, both the ascending part and the angleresemble the human. It may however be stated here that thegorilloid angle region, i.e., a broad angle portion with semi-circular margin, occurs occassionally also in the human jaw,particularly it seems in the Eskimo and some AmericanIndians.

From the anthropometric point of view, the gonial angleshould by rights be written the gonial angles, for thesebelong to the originally separate halves of the jaw, and henceare doubled formations that, while closely related, yet inmany individuals differ more o r less on the two sides. It maybe stated at once, however, that the inequalities in all thebilateral features of the lower jaw, in any larger series, tendto balance, or almost so, so that the means of their nieasure-ments will be similar. This for routine work justifies thetaking of measurements on one side only, and that preferablythe left, which is easier. To dentist and surgeon, 011 the otherhand the individual inequalities must be of direct interestand these professions should be aware of the occasionallymarked extent of the inequalities under seemingly non-pathological conditions.

The gonial angle is measured on the classic Broca smandibu-la r goniometer, which with care allows of but little error,so that the records of various observers must be fairly com-


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284 ALE^ H B D L I ~ K A

parable. The only source of error would be to measure thetwo angles simultaneously, which would result in more o r lessvitiation of the result by the obliquity of the condyles andprotrusion backward of their mesial portions.

The recorded data on the gonial angle suffer, however, fromthe prevalent inadequacy and great unevenness of the series.It was to compensate for this, as far as possible, that thewriter has measured the large materials to be reported uponin this paper. But these should be headed by the olderrecords. The older data on adults will be given in a table ; theymay usefully be preceded, however, by Debierres' (1886)records 011 the angle in the anthropoid apes and in fetusesat term.

Gonia l ang le in a p es(Debierre)

6 gorillas: 95" 4 chimpanzees: 103" !? orangs: 104"ANQLE ANGLE AXOLE

99 106 105100 108101 108102102

Gonial angle in h u m a n young(Debierre)(5) Fetuses at term 128, 130, 140, 146, 180"(30) Children 5 months t o 9 years 121, 150'

In the large anthropoid apes the angle, it is seen, is as arule low, approaching the right angle, nevertheless reachingthe lowest adult human.In the human "fetus at term," the angle, though mostly

wide, raries extensively and may in some cases reach thehigher values of the adult.

Tlie older data on human adults, excepting my own, are asfolloms: The data that I have published will be includedwith the new records.

There are doubtless some records that, hidden in general reports, have escapedbeing iaclutled; but they, it would seein, can be of no gr ea t importance. Andthere are some records, particularly those of Rasche ( '13), in which no separationis made of the two sexes. As the angle differs substantially in the male andfemale, and the sex proportions in the series in question are doubtless uncren,tlie rccolds are almost useless.


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LOWER JAW

Goitial (bodg-ramlts) angle. Older data

JYliites (and related) :MediterraneanFrench NeolithicOld FrenchFrench, recentGreat-RussinnSlavSlavTirolean and BavarimGermanAlsatian and 8.W. Germm

(17-70 years)Old Egyptian (XVII I Dyn.)Berber (Biscra)GuanchePariahs MndrasHinduPolynesianMaoriHawaiianGilbert Island

American Inr7ian:Old PeruvianOld Peruvian American Indian American Indian Pecos PuebloCentral American

Other Pellowbrown:EskimoEskimoEskimoEskimoChukchiGiiliakAinoAino

MALE

( 2 0 ) 1 2 1(6) 115.5

(31 ) 122(12 ) 126

(160) 119( 3 ) 1 2 8

(11) 126(30) 126.2

( 5 ) 1 2 1

( 9 4 ) 1 2 1(15) 122

( 5 ) 1 2 4(5) 113.4( 5 ) 1 2 4( 5 ) 1 1 4Sex not givenSex not given

Sex not given

( 7 ) 1 1 9

(6 ) 11 5(26 ) 118( 1 0 ) 1 1 7

?,ex 8 ( 1 5 )(97) 117.7( 6 ) 122.8( 1 ) 115( 2 ) 115.5(2 ) 129Sex ? ( 1 0 )( 1 ) 1 3 4( 4 ) 1 2 1( 3 ) 1 3 0

(64 ) 123

FBNALE

(6) 123( 1 5 ) 1 2 3( 2 7 ) 1 2 2

( 2 ) 1 3 1( 1 2 ) 1 2 9(30) 127.6( 4 3 ) 1 2 4( 1 5 ) 1 2 4

( 3 ) 1 3 1

. . . .

. . . ..( 4 ) 1 2 1

. . . . .( 5 ) 1 2 2( 2 ) 1 2 5(3) 1 25( 1 5 ) 1 1 6

(15) 117.6(10) 111.6

(4 ) 124. ... . . .( 5 ) 1 1 9

121.1(62) 122.9. .. . . . .. . . . . . ..

(4) 132.2( 8 ) 1 2 6123.3( 1 ) 1 2 2( 4 ) 122( 1 ) 1 2 7

( 3 7 ) 1 2 7

285

RenardBrocaRenardBrocaTarenetzkiRenardFrizziTarenetzkiWelckerKieff erRenardRenardBrocaRenardRenardRenardWelckerWelckerWelcker

FrizziRenardRenardWelckerHootonBrocaFrizziBrocaOettekingWelckerOettekingTarenetzkiTarenetzkiKoganei

IGiven by Topinard, 1885, p. 962, same for all other Brocns data.Used a modified method, which may account f o r his lower values.Writers data on the Eskimo (30) are incorporated into his new da ta, q.v.


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286 ALES H R D L I ~ K AGonial (body - r am u s ) angle . Older data-(Cont inu ed)

JapaneseJapaneseChineseChinese (and related)ChineseChineseMongolKalmuckMalayMalaySiamese

Peltowbrown-Wbite (wig.):LappsLapps

Blacks :New CaledonianNew Hebrides Melanesian PapuanAustralianAustralianAustralianHottentotNubianAfrican NegroAfrican NegroAfrican NegroAfrican Negro

YALE

(3) 132( 8 ) 124.3( 5 ) 132(10) 124

Sex ? (10)(27) 119.9(4 ) 116Sex B (10)

Sex P (24)Sex? (5j(4) 121

(84) 122.3(155) 122.6

(17) 111(13) 117Sex B (10)Sex ? (15)(13) 109(6) 124.7

Sex I (10)Sex I (10)Sex ? (15)(10) 120.4(23) 121(7) 125

(3 ) 119

FEMALE

. ..(2) 130(3) 123.3.. . . .

120.8( 7 ) 126.9(4 ) 122(3) 120

118.1118.7121.1

(48) 128(136) 125.2

(5) 112(2) 119(2) 119112

121.2(3) 116.. . . ..

122115.8117(4) 122(11) 120(3) 123

TarenetzkiToldt, Jr.Toldt, Jr.RenardWelckerHabererBrocaWelckerRenardWelckerWelcker

HerberzSchreiner

RenardRenardFrizziWelckerWelokerBrackebushFrizziWelckerWelckerWelckerBrocaRenardFrizzi

The above records on European Whites show much relationand may with advantage be taken collectively, which gives thefollowing figures:

MALE FEMALE FEMALE : ALEEuropean Whites

(collectively) (212) 122.4 (112) 125.3 108.43

I f jaws with extensive loss of teeth are excluded, these datawithin adult life, it has been shown by Debierre and alsoKieffer, would not be materially affected by age and may


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LOWER J.4W 287therefore for the time being serve as standards. Just whatthe conditions a re in the other racial groups can mostly only besuspected-the records are too insufficient and uneven. Thereare, however, strong indications that the gonial angle, ingeneral, is highest in the Whites (and in the Aino), and pre-valently nearly as high in the Negro; that it is materiallylower in the Melanesians and especially, seemingly, in thePolynesians; and that also it is markedly lower in theAmerican Indians.

To the preceding records, thanks to our collections, I am nowable to add considerable new data and that, moreover, datasecured by the same observer, same instrument and samemethod, and taken very largely sequentially, without pro-longed interruptions.

My method is that of Broca, Topinard, and essentially alsoWelcker. It is the simplest and on the whole most satis-factory. Its attempted alterations by Torok, Keilson, Kieffer,were based more or less on theoretical grounds, have lead tono advantage and found no followers. The instrument I useis the classic Brocas mandibular goniometer ; here againthere were attempted in the course of time several innovations(Torok, Hambruch, Black), without improving the instrumentfo r the study of the angle. The instrument, as is well known,consists of a horizontal plane to which is hinged a plane thatcan be moved up and down, and through a slit in which passesa metal arc, the graduation of which shows the angle of in-clination of the movable part. F o r measuring the gonialangle the lower jaw is laid on the basal part with its alaetoward the movable plank, and the side to be measured, to doaway with any possible interference of the mesial end of thecondyle, is moved so that the antero-posterior plane of theramus is at right angles to the movable portion. The jawis held down so that its gonial part on the side measuredtouches the base, the hinged part as well as the bone aremoved until the former touches the most posterior parts ofthe branch that is being measured, and the angle of inclinationis read off. It would be impractical to try to reach some


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288 -4LEg HBDLI6PA

ideal or more satisfactory angle, as has been attempted. Theregion of the angle varies much, but in the long run thesevariations compensate each other and the results obtainedare quite satisfactory. That this is so the observer mayreadily convince himself by subdividing his materials intoseries of twenty-five or fifty and seeing the closeness of theresults. Measuring the angle in this manner is simple andexpeditious. If any extraordinary conditions are met within a specimen-which will be rare-the observer must usehis trained common sense as to what to do, I n the occasionalinstances of rocking jaws, where the inferior border ofthe bone is convex and there is no well defined gonial angle, thebest appears to be to take the angle in the position of thebone when lying on its base and naturally at rest.

The angle, as already mentioned, in most cases differs moreor less on the two sides ; but the differences have failed in anyof our series to show any defi1iit.e significant trend. Jaws withextensive loss of back teeth should always be excluded fromthis measurement.

The data which I am able to present now are as follows :The gon,ial (body-ramzis) a n g le . A u t h o r s d a t a

Anierican Whites Specs(Mise., N. T.) Mean

RangeOld Egyptians(XI1 Dyn.)

Polynesians( H awai i )

hortli Americati ~ 7 i d i r f ? t . ~CaliforniaPueblos( Ne w Mexico and Arizona)Sioux

JIhrrB

(152)123.6

(105-141)119.8

(1O8-132)(42)

(30)117.8(109-133)(131)114.2

(101-126)(100)

(104-129)(38)

113.6

113.8(101-128)

~

FPMALF.

(146128

(111-147)124.2

(111-136)( 5 0 )

(43)123.4(112-135)(200)118.0

(102-133)(100)120.4

(108-129)(25)117.5

(106-131)

FE3CALE: MALE

103.4

103.7

104.7

10.7.1

1042

m . 3


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L O W E R J A W

The gonial ( body -mmus ) angle. Authors d a l e ( C o n t i n u e d )

289

Florida

Arkansas andLouisiana MoundsPotoniac River (Md.)

Lenape

Alaska Indians (collectively)

Peninsula, Kodiak Island,Aleutian Island *

Eskimo

Mongols

Chinese(Canton district workers)African and American Negro

( ullblood)Kaffir

MALE

(200)112.7

(98-127)(67)118.5

(108-131)(60)118.4

(108-130(8)118

(116-121)(37)118.0

(104-136)(120)116.8

(103-134)121

(100-141)1

(109-133)122.1

(108-137)

(391)

(30)

(66)

(24)120.7(110-137)

(4 )(112-119)115.3

-FEXALB

t200)117.3(101-133)

122(109-134)

( 6 5 )

(60)123.7(111-133)

( 6 )127.8(133-131)

(31)125.0(115-135)

122.6(113)(110-138)(411)125.2

(106-143)125(23)

(112-137)(6)127.2

(120-135)(35)126.3

(115-143)

FEMALE : XALE

104.2

103.

104.5

-(heterogeneous)

104.9

103.5

104.4

104.6

Includes five non-Eskimo groups, the means of which range, niale 115.7-119;female 131.7-123.5.

Reducing the above to nearest whole figures and halves,and arranging the data consecutively, there result the follow-ing interesting relations :


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290 ALE^ HRDLIEKAGonial angle

W hites and rela ted:Miscellaneous Ameriean 'WhiteOld EgyptianPolynesian

Pel lowbrowns:ChineseEskimoOuter MongolPotomac River Algonquiiidrkansas and Louisiana Mounds(related to Algonquin)Lenape (related t o Algonquin)Alaska Indians (collectively)Southwestern Alaska (Aleut, etc.)PuebloCalifornianSiouanFloridianAfrican and American (fullblood) NegroBlacks:

MALE

123.512 011 812 21 2 1120118.5118.5118118117115.5114114112.5120.5

FEMALE

128124123.5127125125123.5122125122.5120.5118117.5117.5126

It is seen that the angle is by no means closely alike in allhuman groups, or even in all the groups of one human stock.Between the group highest in the scale and the lowest thereis in both sexes more than 10 degrees of difference, which iscertainly material. But what the meaning is, is not clear. Thefirst consideration would naturally be given to the massof the jaws and the teeth, and the first three items on thelist would seem to support a conclusion that the angle standsin inverse correlation with this factor. The jaw in the meanis perceptibly stronger in the XI1 Dynasty Egyptians thanit is in the American Whites, and is still somewhat strongerin the Polynesians. But this lead breaks down when we con-sider the Yellowbrowns. The largest and heaviest jaws notonly in America but in recent man of the whole world, arethose of the Eskimo and the Florida Indians-yet in theangle the two stand at the opposite ends of the yellowbrownrange. The Mongol jaw is less massive than that of theEskimo, but the angle in the two is practically equal; whilethe Aleuts and other southwestern Alaskans have lower jaws


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LOWER J A W 291much like those of the Eskimo, but their angle is lower.The Negro has a stouter jaw than the White, yet the anglesare closely similar. The Potomac River Algonquins had adecidedly weaker jaw than the related type of people of theArkansas and Louisiana Mounds, but the angle is almostthe same. The Californians and the Sioux did not haveequally massive jaws, nor did the two belong to the samecephalic or stature type of the Indian, but the angle in theirjaw is identical. The Californians and the Sioux were dolicho-and mesocranic, the Floridians and Aleuts highly brachy-cranic, and the Sioux and Aleuts were among Americas mostlow-vaulted, the Floridians among the most high-vaultedstrains-yet all these show a low angle. N or does the anglein individual strong or weak jaws always conform to thestrength of the bone. It is plain that everything about thelower jaw must be much better known before the causes of thedifferences in the angle can be established. There is doubt-less no definite and universal single cause. Yet in the longrun, strength or weakness of the bone do probably affect theangle, as do the time of eruption and the size of the teeth, thepresence or absence of lower third molars, and the activity andmass of the internal pterygoid muscle; heredity, too, in allprobability, already plays a role. A thorough large scalestudy of individual jaws and of groups with widely differingangles will eventually throw light on these problems.

The most obvious and definite fact shown by the new dataand suggested already in the old records, is the generalpresence of low to moderate angle in the American Indians.In this respect they differ from the Eskimo as well as theMongol and Chinese, they differ especially from the Whites,and they show once more their basic unity. As the severalgroups shown here differed considerably in habits of lifethe peculiarity would seem to be already in the Indian ageneralized racial character. A suggestive fact is that thesouthwestern Alaskan groups, who physically approach theIndian rather than the Eskimo, show gonial angles like thoseof the Indians. It is highly desirable that the Russian workers


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292 ALEB H R D L I ~ K A

give us comparable data on the lower jaws of the nativeSiberians.A g e . Since Debierre's (1886) and Kieffer's ( '07) studies

on the gonial angle in relation t o age, it is known that, at leastin one group of Whites, the average gonial angle does notchange from the time the adult life is reached to at least 70,except where there is extensive loss of teeth. This ruleis probably universal, for no convincing exception to it couldbe found in the various series that I have examined. Whatwas observed was that, after elimination of the plainly senilejaws or those having suffered much loss of teeth, the highestangles found, between 140 and 148, occurred in jaws with allor most of the teeth present and in no instance indicatingold age. Moreover such high angles occur in both sexes. Theyare generally associated with a rather subdeveloped ascendingbranch but high symphyseal region, but in no instance withanything senile or pathological. The other extremes, the jawsin which the gonial angle reaches close to or even below loo",occurred without exception in neither the young nor the oldadults but during the fully developed and presenile period. Inthese cases the lower portion of the ascending branch of thebone was in every instance overdeveloped, the gonial regionpresenting a broad convex margin which protruded backward ;and the whole bone was generally strong; but the height ofthe symphyseal portion was in none of these cases excep-tionally high. Such jaws resemble much some of those of thesmaller lower primates, and may possibly mean a form ofreversion.

Within the well-established adult life, therefore, and beforesenility with its extensive loss of teeth sets in, age alone hasapparently n o material influence on the gonial angle.Size. The size of the jaw, alone, seems also to bear but littledefinite relation to the gonial angle. Certainly the largestjaws do not have the lowest nor the smallest bones the highestangles; but it is not possible to say that there is any directconnection. The point can only be settled by special studies.


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LOWER J A W 293

Sez. Throughout the records, the old (where more ample),as well as the new, the gonial angle in the female lower jawis seen to be 3 to 5 degrees higher. The percental female :malerelation, the male being taken as 100, is especially interesting.The data will here be recapitulated.

Goitial angle in fem ale 2'8. male jn i vs (8= ZOO)American Whites (N. ., misc.) 103.4XI1 Dynasty Egyptians 103.7Polynesians (Hawaii) 104.7American Indians and Eskimo

Arkansas and LouisianaCalif oruiaSiouxEskimoFloridaPueblosPueblos-Peeos (Hooton)Potomae RiverS. W. Alaskans

103.-103.1103.3103.5104.2104.2104.4104.5104.9Other groups:

Aino (Koganei) 103.3Mongols 104.4African and American Negroes 104.6

The correspondences are remarkably alike, ranging lessthan two points, and if all the series were equally ample eventhese differencs would probably diminish. Pe t evidently thereare some differences, and these must have their cause orcauses, though these are not obvious. The female jaw ascompared with male is on the average smaller, lighter, andprovided mostly with a smaller dental arch and teeth-factorsall of which may have some influence on the angle. Here againis a need of further special studies.

With these sex differences, however, there is a great dealof overlapping or interdigitation, which, in individual cases,makes the gonial angle of but limited value for sex identifica-tion. All that may be said on this point is that an angle below118" points towards a male, above 128" towards a female;but there are numerous exceptions.


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294 ALE^ H R D L I ~ K ASide. A measurement of the gonial angle on the two sidesreveals some interesting conditions. Taking three of our

main groups the means of the angle on the right and left were :Gonial angle according to side

XALE FEMALERight Left Right Left

American Whites (N . P. isc.) 133.8 123.6 128.- 128.-Eskimo (in general) 120.9 121.1 125.3 125.-Outer Mongol 119.4 121.- 124.9 123.-

I n the averages, it is plain, there is practically no differencein the angle on the two sides, in any of the groups, and this,there are indications, is the general rule. In view of this factit is wholly legitimate to measure the angle on one side only-for greater convenience the left-unless in a given case thereare reasons to the contrary.

Individually, however, the conditions are very different.Taking in many respects our two most opposed series, we findthe following conditions :

Gonia l angle , d i ferences as to aideMALE FEMALE

Spec's 76 % % Spec's lo 76 76U. 8.Whites(N . Y. misc.) (100) 22 40 38 ( 7 7 ) 18 48 34

Western Eskimo (100) '33 39 38 (100) !?G 45 29

There is practically a n identity of showing in the malesof the two series-another one of those basic points which gofar toward the demonstration of the unity of the humanspecies. The females differ somewhat from the males andbetween themselves, but the differences are very moderate.In scarcely one-fourth of the cases in all the categories arethe angles on the two sides equal; in four-tenths of the malesand not far from a half of the females the angle is slightly to


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LOWER JAW 295

Degrees 1 2 3Male (75) 28 34.7 18.7Female (63) 28.6 31.7 25.4

moderately larger-more oblique-on the right ; n nearly thesame proportion (four-tenths) of cases in the males but in adecidedly smaller percentage in the females, the angle islarger on the left. These conditions, too, must have theirsignificance. They possibly are connected with habits ofmastication, but this is a mere thought. Here, once more, thereis need of further studies.

The individual differences in the angle on the two sides aremostly small, but may read as high as 7 or 8 degrees. I n onecase, in fact, a white male, without any perceptible pathologicalcause, the difference reached 10 degrees. Taking well-pre-served jaws of the American (N . Y. misc.) Whites, thereappeared the following conditions :

4 5 Above 58 - 5.3 5.36.3 3.1 4.8

( G o , 698, 10)( G o , 6,7)

Goniul angle on the two sides i n Amaricnn WiiitesAnele larger on one side than on the other, bv

There is no great or characteristic difference in the show-ing. In roughly 60% of the cases where a difference appearedthis was of but 1 or 2 degrees, or rather immaterial. But in18.6% of the male and in 14.2% of the female jaws the dif-ference ranged from 4 to 10 degrees, and these cases call f o rattention. They must have definite causation. They ought toconnect with some corresponding asymmetries in the maxillae,or in the base of the skull. Here is still another point thatdemands further study.Individual variation in the gonial angle, while ample, is

not excessive. For our entire new series the minimum andmaximum, in the males, ranged from 98 to 141, or 43 units;in the females from 101 to 147 degrees, or 46 units, whichwould be approximately 36 and 37% of the general average.But this is excessive. The actual ranges of the better repre-sented series, in percentage of their individual averages, run


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296 ALEB H R D L I ~ K Ain round numbers from 18 to 34 in the males and from 17to 30 in the females, with the general means of 23 for themales and 21 for the females.2

The most variable is the angle in the Eskimo, though this isdoubtless connected with the large number of specimens fromthat stock; the next being that of the Whites. In the femalejaw the variability of the angle tends mostly to be less than inthe male, but there are exceptions. The next table givesthe ranges in the different major groups.

Gonial angle: ndividual variaton (range average)MALE B E M A L E

Indian, Arkansas and Louisiana (67) 19.4Old Egyptian (42) 20.-Indian, Potomac (60) 20.3Hawaiian (30) 20.4Indians : Pueblo (100) 20.8Indians: California (131) 21.9Indians : Sioux (38) 23.7Chinese (66) 23.8Indians : Florida (200) 25.7American Whites (N. Y.) (152) 29.1Eskimo (391) 33.9

20.520.117.818.617.426.321.327.228.129.6

Ad d i t i o n a l i n fl u en ces . It is quite possible that some influenceon the gonial angle may be exerted by such factors as stature,cranial and facial type, habits and occupations. Possibly thesex differences may be found thus explainable. But suchinfluences cannot, it would seem in view of the data, be eithervery potent or clear-cut. All this however remains to betested and determined. Here is a fine chance f o r some youngworker.

a The expression of the variation by this means, i.e., by giving the range inpercentage of the average, is a simple and very useful procedure, if the seriesdealt with are both ample and near equal. This of course is impossible ofrealization for any wider studies in anthropology which depend on skeletalcollections; but even thus such da ta carry a certain amount of desirable andvaluable information.


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LOWER J A W 297SUMMARY

This section renews attention to one of the major featuresof the lower jaw that has hitherto been inadequately coveredand understood.

New data are given on the gonial angle in 3006 adultpresenile lower jaws, 1492 male, 1514 female, principallyWhite, Indian, Eskimo, and Mongol.

The angle is shown to offer definite group and sex differ-ences. It is, in the main, highest (most oblique) in the Whites,lowest (nearest to right angle) in some of the AmericanIndians.

The mean angle is as a rule higher in the females than inthe males. This holds true evidently for all human groups; andthe relation of the values of the angle in the two sexes isremarkably uniform.In many individual jaws, the angle differs more or less onthe two sides. Mostly such differences are small and practically

insignificant; but in a minor proportion of cases they reachfrom 4 to 10 degrees and are worthy of attention. In any largeseries of specimens, however, these differences as to sidebalance each other, so that no special tendency is observable.The causation of the showings, all through, demands furtherinvestigation.

11. THE BIGONIAL BREADTHFollowing the consideration of the gonial angle of the

lower jaw, it appears logical t o devote attention next to thebigonial breadth, though there is no great interdependenceof the two features. And in this connection it will be foundthat the lower jaw of the Eskimo deserves especial attention.I t is the jaw of a people among whom, due to environmentalneeds, the process of mastication of food reached its recentmans maximum, to which were added the further calls forchewing by the women of frozen garments and skins. As aresult the bone among these people reached a high grade of


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298 ALE$ HRDLI~KAdevelopment in bulk, equalled only by that of their neigh-bors who lived under much the same conditions, and by a fewgroups of the American Indians, such as the robust huntersof the Plains, and particularly the Floridians ;but among thelat ter the massiveness of the jaw was due in part to otherreason^.^

The Eskimo lower jaw could well be defined as the greatestfunctional achievement in recent human jaws, and as such itdeserves all possible attention. Fortunately there are nowavailable in the U. S. National Museum extensive and geo-graphically comprehensive collections of the bone, larger thanthose of any other primitive people except the Indian; theyproceed with considerable probability all from fullbloods ;barring occasional scurvy they are free from pathologicalconditions; and in a large majority of cases they are accom-panied by skulls o r even whole skeletons, which make sexualdetermination quite definite. I n fact sex identification of theadult Eskimo jaw, with due experience and care, is in generalnot difficult.

For the measuring of the bigonial breadth we have theGeneva Agreement, with much subsequent experience. Thedirections of the Agreement are as follows :

Bigonial breadthL a n d ma r k s . The gonions, o r points of the angles formed

by the ascending branches with the body of the lower jaw. Theseparation of the angles is measured by applying the compassto their external surface.' xcess of phosphates and carbonates in food consisting largely of mollusks,

which increased the massiveness of the whole skeleton.


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LOWER J A W 299

Iizstrumeizt. The sliding compass. The bigonial diameter isthe maximum external breadth of the lower jaw at the angles.The above definition would leave little to be desired, did it

not mention the gonions. The use of the term gonions inthe Geneva (and especially in subsequent short Martinsdefinitions 4, is confusing, these points often being whollyindefinite and even where better determinable not coincidingalways with the maximum flare of the angles.

Method, Div. Phys. Anthrop., U. S. N. M.: Use stubbranches of the compass. Apply instrument so that the rodrests on each side against the posterior border of the ascend-ing branch at o r just above the angles, while the branches ofthe compass are brought to the most prominent external pointsat or closely about the angles.

Note. The measurement is generally simple, but in somecases offers difficulties. The greatest prominence may be onthe posterior border of the ramus above the angles; or theangle parts may be more or less introverted. Such cases willcall for the trained common sense of the observer, the guidingquery being always : just what do I want to measure?

Discussioiz. The bigonid diameter. The values of the dataon the bigonial diameter secured by different observers, not-withstanding some differences in technique, should be fairlycomparable, for there is but little room f o r gross error. Agreater difficulty is offered by the very uneven and mostlywholly inadequate series of specimens, and this even in thecase of the white peoples. The principal records on themeasurement that could be located are as follows: traightline distance between the two gonia, i.e., the mandibular angles. roni my Pra ctical Anthropometry, W istar Inst., Phila., 1939.

Martin (Lehrbuch, 2nd ed., 11, SWS).


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The bigonial d ia m eter . Previous d a t a

( 7 j 9.5 ( 3 ) 9.0(23) 9.6 (11) 8.9

QROUP

Fr izz iRenard

Whites:Berber (Bisc ra )O ld E g y p t i a n sOld E g y p t ia n s X V I I I D y n.S l a vGrea t Russ ianOld FrenchS p a n i s hMed i te r r anean , misc.Tiro lean and Bavar ianP a r i a h of M a d r a sH in d uL a p pL a p pPolynesian

Yel lo wbrowis:Anlericun IndianOld Peruv ian (Ancon)Old Peruvian ( 9 )St. Rosa Is., Calif .Peeos Pueblo, Calif .' Anier . Indian 'Calif oruia"Anier . Ind ian ' 'K e n tu c k yL e n a p eArk. and La. MoundsSiouxFlo r idaChineseChinese (or r e la ted )M a la yAinoJ a p a n e s eChineseGil iakGreenlandS o u t h n n ~ p t o n s.Snii th SoundGreen l a n d19 groups, Greenland t o

M i x e d :

0 11er Fellow browns

Alaskan Pen .Melasesinn :New Hebr idesNew CaledonianBisninrck Archip.

Aus t r a l ianAus t r a l ianAf r icnu NegroAf r ican Negro

MALE I BEMALE(7) 9.6 1 (3) 8.5(15) 9.6 (15) 8.5

both sexes(5) 9.79.79.79.859.910.19.19.410.410.410.0

9.39.810.010.210.310.410.510.510.510.510.610.75

9.79.810.210.210.510.510.811.511.511.6

9.79.09.19.29.19.39.6

8.69.29.59.79.0

-9.29.29.459.39.1

9.59.69.659.9

-

-

9.49.49.69.69.711.010.710.4

-

-

both sexes (156) 10.97I

[201) 11.42

(13') 9.4(lij 9.5( 3 ) 9.8(11) 10.2' c c i i 106

(199) 10.57

(2) 9.0(5) 8.8(2) 9.4(3) 8.8- -

O B S E R V E R

RenardRenardOet tek ingRenardTarene tzkpTarene tzkpHoyos SainzTarene tzkyFr izziRenardRenardSrhreinerHerberzHerberz

RenardFr izziMat iegkaHootonRenardHrdliEka ('06)FrizziHrdliEka ( '30)HrdliEka ( '16)HrdliEka ( '09)HrdliEka ( '37'and new)HrdliEka ( '22)H a b e r e rRe n a r dRe n a r dK o g a n e iRe n a r dF r i z z iTarene tzkyOet tek ingH r d l i r k a ( '10)HrdliEka ( T O )F u r s t L% H a n s e uHrdliGkn ( '30)Re n a r dRe n a r dFr izz iBraekebushFr izz i

Measured 3000 skulls of S p a in , b u t g iv e s no ind ica t ion as t o the nun iber o flower jaws.

300


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LOWER J A W 301

The above data show that the Eskimo lower jaw in itsbigonial breadth exceeds materially all other jaws on record.Arranging these roughly from the narrowest to broadest inthe males, and taking the mean of the records where multiple,there is obtained the following sequence:

Groups: 22312631221022

India specs. (1)Old Peru (coast) ( 3 2 )Melanesia (33)Old Egypt (15)African Negro ( 3 0 )

1 2 0 0 )Chinese ( 4 2 )Aino (64)Australian (17)Lapp (237)North American Iiidian (30)Eskimo (212)

European White ( a p p r o x

M A L E9.29.29.59.G9.G9.79.x10.210.310.410.411.45

The figures show several items of interest. The lowestvalues-the most subdued bigonial breadth-is seen in Indiaand on the coast in Old Peru, warm regions of short sedentaryand not robust groups ;while the decided maximum is given bythe Eskimo, next t o whom come the Lapp and the North Ameri-can Indian. The Australian, too, has a broad jaw, but theMelanesians unexpectedly are weak in this respect. TheAfrican Negro has, curiously-so f a r as represented-even atrace narrower jaw than the European White, and both standsomewhat below the mean of the range, with the Chinese closeby. There are then some fairly marked differences in thedimension in various parts of the earth, but most of therecorded series are too small o r restricted for definite con-clusions as to the extent o r meaning of the differences.

The preceding records I am now able to supplement withthose on considerable new materials, particularly from Alaskaand on the American Indian. The data on the Eskimo includethose of 1930,8but there are substantial additions.

Anthrop. Survey i n Alaska.


22/28

Ekm(ngaGea

toPnua

Puua(mixueo

EkmaAes

KakIsans

PeKa

Ka

PeAe

Ae YAeuanIsans

AakIna(mny

ElodIna*

M

(Ug

Cn(Core)

Pya(Hw

U.Whe(NYms)

No(mnyAc

fubo P

cynEkm

BigiaBedhAuthospeenda

Y

FMA

1 1 1 1 1 1 1 1 1 9 1 1 9

( ( ( ( ( ( ( ( ( ( ( (

(

(

1 1 1 1 1 9 9 1 9 9 9 9 9

( ( ( ( ( ( ( ( ( (

9

( (7

)

(

0:6

d100)

9 9 9 9 9 9 9 9 9 9 9 9-

R

Or

IN

VAL

IN%OF

A

*Aoohreeboe


23/28

LOWER J A W 303

MALEPre-Koniag (Kodiak) (64) 11.47Koniag (Kodiak) (33) 11.31Eskimo (in general) (369) 11.28Alaska Peninsula

(Eskimo-Aleut) (18) 11.24Pre-Aleut (39) 11.05Alaska Indian (35) 10.82Florida Indian (100) 10.82Aleut (67) 10.81Mongol (33) 10.77Polynesian (Hawaii) (25) 10.28U.S.White (mise., N.Y.) (107) 10.10Chinese (Canton) (60) 9.99Negro (fullblood, mainly

American) (33) 9.89

FRYALE(92) 10.38(20) 10.47(391) 10.54(19) 10.50(23) 10.20(30) 9.95(69) 9.95(40) 9.54(100) 9.43

(100) 10.05(23) 9.71

(9) 9.52(41) 926

The broadest male jaws, it is seen, are those of the Alaskans,the Eskimo in general, and the Old Floridians, followed by theMongols; the least broad are those of the American whitelaborers and especially those of the Chinese and the Negro.The females follow much the same order, except the Eskimo,which stand at the head of the list, and the Florida Indian, inwhom they stand also higher than the males.

As to the causes of the showing, the thought naturally turnsfirst to stature, and to the shape of the skull. The mean statureof the American Whites, the American Negro and the Poly-nesians was above the general human medium of, in male,ca . 165 cm., that of the remaining groups ranged frommedium to submedium. Narrow heads prevailed in the Pre-Koniag, Pre-Aleut, Eskimo, Polynesian, White, Chinese andNegro, decidedly broad head were characteristic of the Koniag,Aleut, Alaska and Florida Indian, and of the majority ofthe Mongols. There is plainly no clear conformity here, eitherwith stature or head form. The bigonial breadth of the lowerjaw must evidently be potently influenced also by otherfactors. These factors are not fa r to seek. A survey of thebroadest jaws in any group shows that they differ from the restparticularly by the development, both internally and ex-


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304 ALE^ HRDLIEKA

ternally, of the par ts that serve for the insertions of thepterygoid muscles, aside of the masseters the main musclesof mastication. They affect the gonial regions both by theirmass and by their activity. They cause a grooving and thick-ening of the bone, in instances increase its spread at theangles, and, especially, lead to the development of irregularexternal elevations about each angle, and more or less of aflare outward of the border of the bone about, not seldomeven above, the angle. It is essentially these conditions, theabove-medium mass and activity of the pterygoid muscles,that enlarge the bigonial breadth of the jaw, and that meansabove-medium mastication. The bigonial breadth, as all 0s-seous dimensions, correlates doubtless basically with stature ;it is affected also, though much less than the bicondylarbreadth of the jaw, by the breadth of the skull; but the mainontogenetic factor which influences it is the function of masti-cation. It is unquestioiiably for this reason that the nativepeoples of the arctic and subarctic, who consume large quanti-ties of raw or but poorly prepared food, have such broadjaws. The Eskimo woman in particular is known for theamount of chewing she had t o do, and she logically heads allthe rest of the females.

There are two groups in which the conditions need furtherexplanation. They are the old Florida Indians, and theNegro. The lower jaw of the Floridians was huge all over,as was that of the Eskimo and other Alaskans. They doubtlessdid also a lot of tough chewing. But in Florida, as has alreadybeen mentioned, due to the excess of carbonates and phos-phates in the food-principally mollusks-the whole skeletongrew thicker and heavier. As to the Negro, both African andAmerican, large jaws are rare, while those of submediumdevelopment-except in length-are fairly common. Themajority of the Negro groups in Africa had no need of heavymastication, and in America they lived always like the poorersouthern white people. Their jaws now and then exceed thoseof the Whites in certain dimensions, to be dealt with later, butnot in bigonial diameter. Contributing cause to this was


25/28

LOWER J A W 305

probably the occasional narrowness of the Negro base of theskull.An interesting side problem is the condition of the Eskimo

jaw, as to the bigonial breadth, in different groups of thesepeople. The next figures will show the facts. They repre-sent practically the whole Eskimo habitat, outside of Labrador,from which collections are still insufficient.

B i y o a ial b r e a d t h among the E ~ k i m o

Barrow RegionSt. Lawrence IslandPoint HopeWestern RiversGreenlandSeward PeninsulaWestern Coast and Islands (Bering Sea)

(122) 11.311.4

(13) 11.4(63) 11.5(22) 11.8

FEYALE

(23) 10.3(59) 10.6(124) 10.6

( 6 6 ) 10.3(21) 10.4(71) 10.6(23) 10.8

These differences show no distinct correlation with eithergeographical or any other known factors. They may to someextent be due to insufficiency and unevenness of the numbersof specimens in the different series. What is plain is that allthe groups had broad jaws.

The female :male relation in the bigonial breadth rangesfrom 90.2 in the Mongols and 90.5 in the Pre-Koniag peopleto 93.4 on the Peninsula and in the Eskimo, and 93.6 in theNegro, where the female jaw relatively to that of the maleis the broadest. There is really a remarkable general similarityin this respect. The differences, which would probably befurther reduced if we had throughout adequate numbers ofspecimens, are doubtless of functional character.

SUMMARYThe older records on the bigonial breadth of the lower jaw

are here supplemented by those on substantial series of speci-mens from the Eskimo, various other groups from Alaska, theAmerican Indian, the Mongol, Chinese, Polynesian, Negro,and miscellaneous American Whites.


26/28

306 ALES H R D L I ~ K A

The breadth shows material differences in the differentgroups aside of such as might be attributed to the influenceof stature or the breadth of the head. The broadest jaws arefound in the arctic and subarctic peoples, the least broad insouthern groups including the Melanesians and the Negro.

There are definite indications that the dimension underconsideration is largely influenced by the development of thepterygoid muscles, which in turn are proportionate to theamount and nature of mastication.The differences in the bigonial breadth of the jaw in dif-ferent human groups may therefore be safely accepted asmainly of ontogenetic, functional, causation.

L I T E R A T U R E C I T E DANNANDALE, . , AND H. C. ROBINSON 1903 Anthropological and Zoological

Results of a n E x p e di ti o n t o P e r a k a n d t h e S i a m es e M a lay s t a te s .Fasc . Malay., sm. 4to (m easure me nts of lower jaws p. 155).Be i t r a g e zur Anatomie des mensclilichen Unterkiefers 1. Ubereinige Ma ss- und Z ahlenverhaltnisse d. U nterkiefers. 2. U b e r d e nProcessus lemur in ious (Sandifor t i i ) . Inaug. Diss. med. Konigsberg,

BRACKEBUSCH,. 1905 Die Austral ierschadel der Sammlung des AnatomischenI n s t i t u t s zu Wittingen Inaug. Diss. , Gtt .

BROCA,P. 1875 Ins tru ct ion s cranialogiques e t craniometr iques M6m. SOC.Anth rop . Par i s , 2 me sbr., I1 a n d 8, Par i s . Measurements of theMandib le pp . 93-96.

DEBIERRE , C. 1886 Sur le dbveloppemen t, 16volution, e t sur Iangle de laml cho ire inf6r ieure. Bull. SOC. nthrop . Lyon, V, 185.FRIZZI,E. 1910 Untersuehungen am menschliehen Un terkiefer m it spezieller

Ber i ick s ich t ignng der Regio mental is . Arch. Anthrop., IX, 252-286.FITRsT,. M., AN D Fa. C. C. HANSEN 1915 Cran ia Groenlandica. Copenhagen,

167 e t seq .GORJANOVIB-KUMBERQER,. 1909 Der Unterk iefer der Eskimos (Gronlander)

als Tr ag er pr imit iver Merkmale. Si tz .-Ber . Preuss . Akad. Wise., LII,

BOSSE,U. 1901

37 PP-

1282-1294.HABEREB,. A. 1902 Schadel und Skeletteile aus Pek ing , Jena .HOOTON,. A. 1930HOYOS SAINZ, ., A N D T. ARAMADI

The India ns of Pecos Pueblo , New H ave n; lower jaw pp .Notes prel iminaires sur l e s Cran ia

68-69.1913

Rispanica. Bull . an d M6m. SOC.Anthr . Paris, IV, 81-94.


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LOWER JAW 307HRDLI~KA,. 1930 Anthropological Survey in Alaska. 46th Ann. Rep. Bur.

1922 The -4nthropology of Florida, Publ. Fla. St. Hist. SOL,1909 Report on an additional collection of skeletal remains from1906 Contribution to the Physical Anthropology of California.1937 The Minnesota Man. Am. J. Phys. Anthrop., XX, 195.1916

Am. Ethnol., Wash.

Delano, Fla., sm. 4to.Arkansas and Louisiana. J. Ac. Nat. Scis. Phila., XIV, 196.

Univ. Calif. PubIs, IV, no. 2, pp. 49-64.Physical Anthropology of the Lenape, etc., Bull. 62, Bur. Am.

Ethnol., Wash., 130 pp. (Lower jaw p. 31.)KEILSON, . 1904 Anatomische und topographische Untersuchungen iiber denCondylus mandibulae und den Meatus auditorius externus. Iiiaug. Diss.Berl.

KIEFFEB, . 1907 Beitrage zur Kenntniss der Veranderungen am Unterkieferund Kiefergelenk des Menschen durch Alter und Zahnverlust. Z.Morphol. & Anthropol., XI, i-82.

IILAATSCH,. 1899 Die fossilen Knochenreste des Menschen und ihre Be-dentung fu r das Abstammungs Problem. Erg. Anat. & Entwickelungs-gesch, I X : Unterkiefer pp. 462-471: (Nothing as to measuring;discussion of characteristics of lower jaws of Early Man known tothat date).

KOGANEI,. 1893 Beitrlge zur pliysischen Anthropologie cler Aino. Tokyo.KURZ, . 1918 Der Unterkiefer des Gxinesen. Arch. Anat. Phys. Anat., Abt. S.

1922 Die Form des Saugetierunterkiefers. Inaug. Diss. Fr an kf ur t173-209.

a. M.MARTIN, . 1905 Die Inlandstamme der malayischen Halbinsel. J ena.MARSELLI,. Sul peso del cranio e della niandibola in rapport0 col sesso.OETTEICIBO,. 1909 Kraniologische Studien an Altagpptern. sin. 4t0, Braun-PUCCIONI,. 1914 Morphologie du maxillaire infkrieur. Anthropologie, Par.,RASCHE,W. 1913 Beitrage zu r Anthropologie des Unterkiefers. Inaug. Diss.

Zurich.RENARD,. 1880 Des variations ethniques du maxillaire inf6rieur. These, Paris,SCHREINER,


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ALES H R D L I ~ K ATARENECKI,. Weitere Beitrage zur Craniologie der Bewohner von Saehalin,

MBm. Acad. Scs St. Petersb., XLI, no. 6.TOLDT,C., JR. 1903 Die Japanerschadel des Miin-scliener anthropologischen

Institutes. Arch. Anthrop., XXVIII, 143 et seq. (Lower jaw p. 180).TOPINARD,. 1885 Elembnts dhnthropologie gBnBrale, Paris 8,Mandible pp.TOR~K, . v. 1898 Ueber Variationen und Correlationen der Neigungsverhalt-WALLISCH,W. 1909 Das kiefergelenk. Arch. Anat. & Physiol., Anat. Part,

WELCKER, . 1902 Die Zugeltorigkeit eines Unterkiefers zu einem bestimmten

1893

960-962.nisse am Unterkiefer. Z. Ethiiol., XXX, 125 et seq.111.

Schadel, etc. Arch. Anthrop., XXVII, 37-106.

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Ales Hrdlicka 1940