In1831,ayoung,English naturalistnamedCharlesDarwinboardedashipcalledthe Beagle. Hewasheadedonafive‑yearexpedition.Histask?Tocollectandstudyanimal,plant,androcksamples.Darwinwouldbecomeoneofthemostfamousscientistsofhistime.Hecontributedtothe theory ofevolution.Heproposedthatalllivingthingshavedescendedfromcommon ancestors.

Whatislesswell‑knownaboutDarwinisthathewaspronetoseasickness.Asaresult,Darwinwasalwaysthefirsttogoashoreandthelasttoleaveit.Becauseofthat,hiscollectionofsampleswasbothlargeand diverse.

Darwintookmanynotesandkeptajournal.AlongwiththelogsoftheBeagle’scaptain,RobertFitzRoy,theyhelpustoknowexactlywheretheytraveledandwhatthey collected.

TheBeagle reachedtheGalápagosin1835andspentfiveweeksthere.Darwinvisitedfourofthelargerislands.SanCristóbalwasfirst.Madeupoffourextinctvolcanoes,itishometotheoldestpermanentsettlementofthe islands.

SanCristóbal’sdry,rockycoastwasnotwhatDarwinwasexpecting.Theislandseemeddevoidoflife.Hefoundpatchesofdesertplants.Inapartlyvegetatedlavafield,hefoundtwoenormoustortoises.Theyweregrazingoncactus.Here,Darwincollectedthefirstspeciesthatwouldbecomethefoundationofhistheory,theSanCristóbal mockingbird.

Floreanawasthesecondislandtobeexplored.Darwinspentthreedaysherecollectingsamples.Theseincludedasecondimportantbird,theFloreanamockingbird.ThedistinctdifferencesbetweenthisbirdandtheonefoundonSanCristóbalpromptedDarwintopaycloseattentiontoGalápagos birds.

OnFloreana,DarwinalsometwithafellowEnglishmannamedNicholasLawson.Hewastheactinggovernorfortheisland.LawsontoldDarwinthathecouldidentifywhichislandatortoisecamefrom.How?Bylookingatitsshell.Eachisland’stortoisesweredifferent,hesaid.Darwinwonderedabout that.  

ThevolcanothatisIsabelaIslandwaseruptingwhenDarwinexploredit.Heobservedlavaflowsandsmokecomingoutofcraters.Hetookdetailednotesandcollectedland iguanas.

ItwasSantiagoIslandwhereDarwinstayedthelongest.HerehesawwhatLawsonhaddescribed:Thetortoiseswere different.Darwinhadcollectedvastamountsofsamples.Yet,hedidn’tunderstandwhathewas seeing.

Ofthemockingbirds,hecouldseefourdifferentspecies,eachfromdifferentislands.Thefincheshe’dcollectedseemedtobedifferent, too.

Darwingavethesamplestothe ornithologist JohnGouldtoexamine.Gouldfoundthattheyweredifferentenoughtojustifyatleast14 species.Darwinwouldponderthisfor years.