FormingaTheory
Darwinbegantorealizethatthebirds’isolationontheislandsmayhaveresultedinspecialadaptation.Thesechangeshappenedslowlyovertimeuntilnewspecieswereformed.HebelievedthatthefinchesandthemockingbirdseachcamefromacommonancestorinSouth America.
Darwinwasn’ttheonlyscientisttobeformulatingthistheory.Severalnaturalistshadalreadydevelopedthisideabytheendofthe18thcentury.Darwin’sgreatcontributiontosciencewasthathewasabletoexplainhowandwhyevolution occurred.
Españolacactus finch
largeground finch
AllofDarwin’sthinkingcametogetherin1859.ItwasthenthathepublishedabookcalledOntheOriginofSpecies.Init,heproposedthatspeciesevolveandthatalllivingthingscantracetheirdescentbacktoacommon ancestor.
Darwinalsosuggestedamechanismforevolution:naturalselection.Thissaysthatsomeplantsandanimalshavetraitsthatworkbestinaparticularplace.Theselivingthingsaretheonesthatwillsurviveandreproduce.Theypasstheirtraitstotheir offspring.
Overtime,apopulationchanges,orevolves,tobetterfitwhereitis.Itmayevolveinsmallways.Forexample,sizeorfurcolormaychange.However,withenoughtime,anentirelynewspeciescan emerge.
ThesamplesDarwincollectedontheBeagleexpeditionandthethinkingthatcamefromhisobservationscontributedtosignificantchangesinhowpeoplesawthenaturalworld.Hiscontributionstosciencewillalwaysbe remembered.
