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Extinction:APlanetinCrisis

ByTomMitchell

Extinctionisanaturalprocessdefinedwhenthelastexistingmemberofaspeciesdies.Scientific

certaintywhen

there

is

not

abreeding

pair

(male

and

female)

of

specie

it

will

become

extinct.

There

are

twotypesofextinction;NaturalandHumanCaused.Generallyextinctionshappenallthetimeinthe

naturalprocess,however,thereareperiodsintimewherelargenumbersofspecies(plantandanimals)

perishduringatimeperiod.Thisisknownasmassextinction.ThishashappenseveraltimesinEarths

historyandmanyscientistsbelieveweareinthemidstofmassextinctionalsoknownastheHolocene

Extinction.TheHoloceneErahasbeendubbedtheHumanCausedExtinctionwithsomescientistsdating

itback50,000yearsagowhenmanleftAfrica.Homosapienswereabletoadapttothedifferent

environmentsthroughouttheworldallowingmantoevolveandgrewdramaticallyinpopulationevento

thisdate.

However,sincethebeginningoftheIndustrialRevolutionmanhasflourishedimmensely.In

1800mansestimatedpopulationwasatonebillionwhichhasgrowntoseventimesthisin200years.

Nolargevertebrateanimalhasgrownthisfastinthehistoryofearth.accordingtotheCenterfor

BiologicalDiversity. Duringthisperiod,theriseinextinctionratesisdirectlyproportionaltothegrowth

ofthehumanrace.Thecontributingfactorsforextinctionareoverpopulation,pollution,global

warming,destructionandfragmentationofhabitat. Manscarbinefootprintnowcovers50%ofEarths

landmasswith40%ofitdevotedtohumanfoodproduction.Thisisupfrom7%in1700.Humans

annuallyconsume42%oftheEarthsterrestrialnetproductivity,30%ofmarineproductivityand50%of

thefresh

water.

Simple

put

man

is

dominating

the

planet

and

is

truly

the

super

predator.

Thehumanimpactonotherspeciescanbeseeninfunctionalextinctionwhenonlyahandfulof

speciesisleftandoddsofreproducingareslim. SomespeciesliketheQuaggahadafunctional

existenceandbecameextinctinzoosthroughouttheworld.Becausetheywelocatedinseparateparts

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oftheworlditwasunlikelythatabreedingpairwouldhaveboreoffspring.Moreoftenthannot,

functionalextinctionoccurstospecieslivinginasmallordefinedecosystem.IntheQuaggascasethey

wereindignanttoSouthernAfricaandwerehuntedtoextinctionbymanformeat,leatherandasa

competitortolivestock. ThelastQuaggaperishedin1883intheAmsterdamZoo.Theextinctionofthe

QuaggawasntknownuntilyearslaterbecausethewordQuaggawasusedforallmembersofthe

Zebrafamily.

Therateoftheextinctionofspeciesisdirectlyproportionaltohumanpopulationas

aforementioned.ThefollowingUSGSgraphdepictsthis:

Thegreatestfactorforextinctionishabitatdegradationcombinedwithhuntingpressure.It

accountsforalmostallextinctionsoccurringinthelastseveralthousandyears.Lossofhabitatand

degradationaffect86%ofallthreatenedbirds,86%ofmammalsand88%ofamphibians.ThePassenger

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Pigeonisagreatexampleofhowdeforestationorlossofhabitatcancauseextinction.ThePassenger

Pigeonwasnumberedinthebillionsandbecameextinctinlessthan200yearsonceEuropeansarrived

inNorthAmerica.Removalofcommunitynestingtreesdisruptedthereproductionoftheillfatedbird

andeventuallymanhuntedthemtoextinction.AsimilarlossofhabitatcausedtheColumbianGrebeto

becomeextinct.IndignanttothewetlandssurroundingBogota,ColumbiatheColumbianGrebebecame

extinctionwiththedestructionofwetlands,siltationandreedharvests.Manandotherpredatory

animalsfoundtheColumbianGrebeeasiertohuntandsoonbecameextinctby1977.

AirPollutionandGlobalWarmingarealsobigcontributorsofanimalextinctions.Inthelast250

yearsatmosphericconditionsinvolvinggreenhousegaseshaveincreasedtheconcentrationlevelsof

CO2(carbonedioxide)by31%,CH4(methane)by151%andNO2(nitrogendioxide)by17%.Humansare

currentlypumpingsixbilliontonsofcarbineemissionsintotheatmosphereinspiteofknowledgeit

promotesclimatechanges.Theburningoffossilfuelsandmodernagriculturepracticesarethe

contributingfactorsfortheelevatedlevelsgreenhousegasesincreasetheplanetstemperatureand

leadstotheextinctionofspecies.TheGoldenToadofCostaRicaandotherCentralAmerican

amphibians

are

prime

examples

of

this.

The

Golden

Toad

thrived

in

a

ten

square

kilometer

area

of

tropicalforestsurroundingMontverde,CostaRica.TheGoldenToadlastbredinnormalnumbersin

1987andin1989itwaslastseen.TheprimarycauseassociatedwiththeGoldenToadsextinctionis

climatechangeandthechytridfungus.Theirhabitatbecamedryer,causingpoolstheybreedintodry

beforetheoffspringcouldhatch.Thechytridfungusismoresuitedforthedryerconditionsandbecame

thetangibletobringtheGoldenToadtoextinction.

Naturalcauses

of

extinction

are

not

so

much

different

than

human

causes,

except

most

take

placeoverthousandsandmillionsofyears.Mostspeciesgoextinctionbecausetheyaremore

susceptibleenvironmentalchangesorarelimitedtoadefinedgeographicalarea.Theybecomemore

pronetodiseasesandclimaticchangesthatmayoccurinthenaturalcycleoftheEarth.Moreoftenthan

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notspeciesgonaturallyextinctbecausetheylacktheabilitytoadapttoachangingenvironment.

CharlesDarwinsTheoryofEvolutionoutlinesthisprocess

DarwinsTheoryofEvolutionpresumesthedevelopmentoflifefromnonlifeandstressesa

purelynaturalistic(undirected)descentwithmodification.Thisistheprocessofrandomgenetic

mutations.Thismutationoccurswithinanorganismsgeneticcodeprovidingalifesavingmutationto

aidsurvivalorbetterknownasnaturalselection.AccordingtoDarwin,Naturalselectionactsonlyby

takingadvantageofslightsuccessivevariations;shecannevertakeagreatandsuddenleap,butmust

advancebyshortandsure,thoughslowsteps." Thisinsuresonlythespecieswiththebestgenetic

designschangeslowlywiththeenvironmentwhileothersbecomeextinct.ThisisalsowhatDarwin

referredtoassurvivalofthefittest.

However,evolutionandgenemutationscantsavespeciesduringamassextinction.Mostmass

extinctionsoccurovermillionsofyears;theexceptionbeingisthePaleoceneerawhenalargeasteroid

struckplanetearth65millionyearsago.Thereisnogeologicalevidencetheremainingmassextinctions

weretheresultsofasteroidsandscientistsuggestanewtheorycausedbygreenhousegasesorbetter

called

Greenhouse

Extinctions.

Paleontologist

and

science

writer

Peter

Ward

believes

there

is

a

correlationbetweenCO2levels,climatechangesandextinctions.Wardstates,"Thekeytoclimate

changeseemstobeboththelevelandtherateatwhichcarbondioxiderisesintheatmosphere."

ThePermianExtinctionoccurred250millionyearsagoandisthoughttobecausedbyvolcanism

activitywhichpumpedtonsofgreenhousegasesintotheatmosphere. Earthsaw90%offspeciesand

nearly97%ofalllivingthingsdie.BenjaminBlack,aMITStudentandexpeditionleaderofarecentvisit

toSiberian

Traps

is

quoted

as

saying

by

Jennifer

Chu

of

MIT

News

Office,

Theres

evidence

that

this

was

arelativelywarm,highcarbondioxideworld,Blacksays.InsomewaystheendPermianenvironment

couldhavebeenverysimilartothekindofenvironmentthatwerecreatingthroughglobalwarming.

BlacksfindingswerepublishedintheJanuary9theditionofjournalofEarthandPlanetaryScience

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letters.Blacksresearchteamsfoundgreenhousegaslevelsthatincludebetween6,300and7,800

gigatonnesofsulfur,between3,400and8,700gigatonnesofchlorine,andbetween7,100and13,700

gigatonnesoffluorinethatwerereleasedfrommagmaintheSiberianTrapsduringtheendofthe

Permianperiod.

Thecommonthreadbetweennaturalextinctionsandhumancausedextinctionappearstobe

globalwarmingcausedbygreenhousegases.Thedifferenceisthetime.Extinctionratesaredirectly

proportionaltothegrowthofhumanpopulation.Thisisdocumentedbyscientificdatapredictsgreater

numbersofextinctiontocome.HarvardbiologistE.O.Wilsonestimatesthat30,000speciesperyear

(orthreespeciesperhour)arebeingdriventoextinction,accordingtotheCenterforBiological

Diversity.Scientistarerelativelyhelplesstopromotechangesinoureconomicpoliticalworldandthe

resultcouldbecatastrophicwithinthenext30to40years.Theonlyquestioniswhenwillnaturedecide

totakebackherplanetandwillmansurvive.

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References

"ATheoryinCrisis."Darwin'sTheoryOfEvolution.AllAboutScience.org,2012.Web.12April2012.

.

Chu,Jennifer."Aneruptionfueledextinction?."MITNews.MITNews,11Jan2012.Web.8May2012.

.

"OverpopulationandExtinction."CenterofBiologicalDiversity.CenterofBiologicalDiversity,201o.

Web.14April2012.

Robinson,B.A.."PossiblelinkageofpastglobalspeciesextinctionswithC02

level:."ReligiousTolerance.org.ReligiousTolerance.org,25Junw2006.Web.14April2012.

.

."SpeciesExtinctionvsHumanPopulationGraph."U.S.DepartmentoftheInterior|U.S.Geological

Survey.U.S.DepartmentoftheInterior|U.S.GeologicalSurvey,2011.Web.12April2012.

Mitchell,Tom."Extinction."Honors380Seminar.UniversityofWisconsinMilwaukee.Milwaukee.April,

18,2012.Lecture.