Core questions in domestication research | PNAS

The domestication of plants and animals marks a major evolutionary transition in human history—one with profound and lasting global impacts. The ... Skiptomaincontent PNASMarch17,2015112(11)3191-3198;firstpublishedFebruary20,2015;https://doi.org/10.1073/pnas.1501711112 MelindaA.ZederPrograminHumanEcologyandArchaeobiology,DepartmentofAnthropology,NationalMuseumofNaturalHistory,SmithsonianInstitution,Washington,DC20560FindthisauthoronGoogleScholar FindthisauthoronPubMed Searchforthisauthoronthissite Forcorrespondence: [email protected] ContributedbyMelindaA.Zeder,January26,2015(sentforreviewDecember5,2014;reviewedbyGaryW.CrawfordandFionaB.Marshall) Article Figures&SI Info&Metrics PDF SignificanceDomesticationofplantsandanimalsmarksamajortransitioninhumanhistorythatrepresentsavibrantareaofinterdisciplinaryscientificinquiry.Considerationofthreecentralquestionsaboutdomestication—whatitis,whatitdoes,andwhyithappened—provideaunifyingframeworkfordiverseresearchonthetopic.Domesticationisdefinedintermsofacoevolutionarymutualismbetweendomesticatoranddomesticateandisdistinguishedfromrelatedbutultimatelydifferentprocessesofmanagementandagriculture.Domesticationresultsinarangeofgenotypic,phenotypic,plastic,andcontextualimpactsthatcanbeusedasmarkersofevolvingdomesticatoryrelationships.Aconsiderationofcausalscenariosfindsgreaterempiricalsupportforexplanatoryframeworksgroundedinniche-constructiontheoryoverthosederivedfromoptimalforagingtheory.AbstractThedomesticationofplantsandanimalsisakeytransitioninhumanhistory,anditsprofoundandcontinuingimpactsarethefocusofabroadrangeoftransdisciplinaryresearchspanningthephysical,biological,andsocialsciences.Threecentralaspectsofdomesticationthatcutacrossandunifythisdiversearrayofresearchperspectivesareaddressedhere.Domesticationisdefinedasadistinctivecoevolutionary,mutualisticrelationshipbetweendomesticatoranddomesticateanddistinguishedfromrelatedbutultimatelydifferentprocessesofresourcemanagementandagriculture.Therelativeutilityofgenetic,phenotypic,plastic,andcontextualmarkersofevolvingdomesticatoryrelationshipsisdiscussed.Causalfactorsareconsidered,andtwoleadingexplanatoryframeworksforinitialdomesticationofplantsandanimals,onegroundedinoptimalforagingtheoryandtheotherinniche-constructiontheory,arecompared.domesticationmutualismgeneticimpactsecophenotypicimpactsniche-constructiontheoryThedomesticationofplantsandanimalsmarksamajorevolutionarytransitioninhumanhistory—onewithprofoundandlastingglobalimpacts.Theoriginsofdomestication—whenandwhere,how,andwhyourancestorstargetedplantandanimalspeciesfordomestication—isanenduringandincreasinglyactiveareaofscientificinquiryforresearchersfrommanydifferentdisciplines.Enhancingpresent-dayproductivityoflong-standingandrecentlydomesticatedspeciesandexploringsocialandbiologicalissuessurroundingtheirroleinfeedingrapidlyexpandingglobalpopulationsaretopicsofpressingconcern.Thevolumeandbreadthofdomesticationresearchisunderscoredbyakeywordsearchontheterm“domestication”fortheyear2013whichyieldedatotalof811papersinmorethan350differentjournals(TableS1),including42articlespublishedinPNAS(TableS2).Giventhelargeandgrowingnumberofstudiesondomesticationacrossawidearrayofdisciplines,itisworthwhiletoaddressthreecentralquestions.(i)Isthereadefinitionofdomesticationapplicabletobothplantsandanimalsfromthedistantpasttopresentdaythatdistinguishesdomesticationfromrelatedprocessesofresourcemanagementandagriculture?(ii)Howdoesdomesticationchangeboththedomesticateanddomesticator,andhowcanwetrackthesechangesthroughtime?(iii)Whydidhumansdomesticateplantsandanimals,andaretherecommoncausalfactorsthatunderlietheprocessofdomesticationwhereverittakesplace?DefiningDomesticationandDistinguishingDomesticationfromManagementandAgricultureThereisasurprisinglackofconsensusonhowtodefinedomestication.Beyondagreeingthatitinvolvesarelationshipbetweenadomesticatorandadomesticate,thereislittleagreementonwhatthisrelationshipentailsorhowandwhenitresultsinthecreationofadomesticatedplantoranimal.Domesticationisfrequentlydefinedfromtheperspectiveofthedomesticator,emphasizingtheroleofhumansinseparatingatargetdomesticatefromfree-livingpopulationsandassumingmasteryoverallaspectsofitslifecycle(1).Domesticationhasalsobeenviewedasamutualistic,symbioticrelationshipthatbenefitsbothdomesticatoranddomesticate(2),withdomesticatessometimesconsideredashavingbenefitedmorethantheirhumanpartners(3).Someresearchersseegeneticallydrivenchangeinadomesticate’sphenotypeasthecentraldefiningcharacteristicofdomestication(4).Othersmaintainthatsuchanemphasismisdirectsattentiontoanarrowaspectofdomesticationthatmayvaryfromcasetocase,orseemnottooccuratall(5).Insteadoffocusingontheeffectsofdomestication,somearguethatdomesticationshouldbedefinedintermsoftherelationshipbetweenhumansandtargetspeciesthatcausesgeneticandotherresponses.Thisshiftinfocussometimesresultsinabroadeningofthedefinitionofdomesticationtocoveramuchwiderarrayofhumaninteractionswithplantsandanimals(6),includingdeclaringaspeciesdomesticated“wheneveranotherspeciesknowshowtoharvestit”(5),orproposalsforreplacingthetermdomesticationwithlessprejudicialonessuchas“culturalcontrol”(7).Againstthisconfusingbackdropofconflictingapproachestoconceptualizingdomestication,thefollowingdefinitionisoffered:Domesticationisasustainedmultigenerational,mutualisticrelationshipinwhichoneorganismassumesasignificantdegreeofinfluenceoverthereproductionandcareofanotherorganisminordertosecureamorepredictablesupplyofaresourceofinterest,andthroughwhichthepartnerorganismgainsadvantageoverindividualsthatremainoutsidethisrelationship,therebybenefittingandoftenincreasingthefitnessofboththedomesticatorandthetargetdomesticate.Thisdistinctivekindofmutualismisnotrestrictedtohumansanddomesticcropsandlivestockbutiswelldocumentedinnonhumanspecies,especiallyamonganumberofsocialinsectdomesticatorsandtheirplantandanimaldomesticates(8).Domesticatoryrelationshipsbetweenorganismssuchasleafcutterantsandfungi,however,arisethroughagradualcoevolutionaryprocessofselectionoperatingonmutation-inducedbehavioral,physiological,andmorphologicalchangesinbothpartnersthatarepassedontooffspringthroughthehit-or-missprocessofsexualreproduction.Humans,incontrast,areabletoopportunisticallyinventandmodifybehaviorsthatenhancebenefitsgainedfromcoevolutionaryrelationshipswithtargetspecies,and,mostimportantly,humansareabletotransmitbehaviorsthatmeetperceivedgoalsnotonlytotheiroffspringbutmorewidelytoothersoutsidetheirimmediatekingroupthroughsociallearning(9).Thishumanabilitytochoosebetweengeneticvariantsofpartnerspecies,toleaveonerelationshipinfavorofanother,toconsciouslymanipulateasymbiont’slifehistorytothedomesticator’sbenefit,isthekeyfeaturethatdistinguisheshumandomesticatoryrelationshipsfromthosebetweennonhumanspecies(8).Contraresearcherswhorejecttheroleofdeliberateintentoragencyinearlyhumandomesticatoryrelationships(3,10),itispreciselythiscapacityforgoal-orientedbehaviorthatmakeshuman-drivendomesticationqualitativelydifferentfromthatbetweennonhumanpartners.Clearlythegoalofthesebehaviorswasnottodeliberately,inateleologicalfashion,domesticateanotherspeciesorinventagriculture.However,decisionstomodifyenvironments,moveplantsandanimalstonewenvironments,andselectivelyharvestandbreedcertainspecies—decisionsthatinitiatedandfosteredthedevelopmentofthemutualisticrelationshipsatthecoreofdomestication—were,nonetheless,arrivedatconsciouslywithdefinedgoalsinmindmadepossiblebytheuniquelyhumanabilitytospontaneouslyinventnewbehaviorsandtopassthemontoothers(11).Thedefinitionofferedheredoesnotencompassgeneticorplasticresponsestodomesticationineitherthedomesticatorordomesticate.Definingdomesticationintermsofthesechangesbegsthequestionofhowmanygenesandhowmuchphenotypicchangeisneededtodistinguishbetweendomesticationandotherkindsofadaptiveresponsesthatmightoccurastheresultofmanipulationofaspeciesoritsenvironment.Similarly,definingdomesticationintermsofthedegreetowhichtheplantoranimalisincorporatedintohumansocioeconomicorganization(12)misdirectsattentiontowardaspectsoftherelationshipthatarenotuniversalandawayfromtherelationshipthatmoreproperlyliesatthecenterofanydefinitionofdomestication.Althoughtheproposeddefinitionfocusesontherelationshipbetweenpartnersratherthanonthebiologicalorculturaloutcomesoftherelationship,italsodiffersinsignificantwaysfromdefinitionsthatemphasizethedomesticator’sroleincontrollingorharvestingthedomesticate.Suchdefinitionsareactuallymorerelevanttotheterm“management,”whichforpurposesherecanbedefinedas:themanipulationoftheconditionsofgrowthofanorganism,ortheenvironmentthatsustainsit,inordertoincreaseitsrelativeabundanceandpredictabilityandtoreducethetimeandenergyrequiredtoharvestit.Thisbasic“niche-constructing”behavioriswidelypracticedbyhumansandnonhumanspeciesandisarguedtobeamajordriverofevolutioninboththeniche-constructingspeciesandotherspecieslivingwithintheconstructedniche(13).Someformofmanagementisanessentialprerequisiteofdomestication,butitisnotsufficientforthedevelopmentofadomesticatoryrelationship.Managementthatdoesnotsubstantiallyaltertheselectivepressuresonthemanagedresourcefromthoseexperiencedinafree-livingstateorthatdoesnotpersistoverseveralgenerationsofthemanagedpopulation(i.e.,thatreliesoncontinuousrestockingfromfree-livingpopulationswithoutbreedingorcloningmanagedindividuals)willlikelynotleadtodomestication.Inorderformanagementtoresultindomestication,asustainedmultigenerationalrelationshipmustdevelopbetweenthemanagerandthemanagedfromwhichbothreapmutual,althoughnotnecessarilysymmetrical,benefits.Sustainingtherelationshipoverthelongtermrequiresthatbothpartnersundergomodifications(geneticallydrivenorfacultative)thatenhancethebenefitseachaccrues.Inanevolvinghuman/plantdomesticatoryrelationships,forexample,thedevelopmentofartificialirrigationbenefitsthehumanpartnerbyincreasingtheyieldoftheplant,whilealsoincreasingtheirrigatedplant’sreproductivesuccessoverpopulationssituatedoutsidetheirrigationsystem.Adaptationsthatmightmakeaplantamoreattractivepartnerincludealterationsinphysiologicalfunctionscontrollingripeningsynchronythatbenefithumansbymakingharvestschedulesmorepredictable,whileincreasingtheprobabilitythatindividualsripeningatthesametimedominateseedstockreservedfornextyear’splanting.Suchmodificationsnotonlyincreasemutualbenefitstobothpartners,theymayalsomakeoneorbothmoredependentontheother,limitingopportunitiestoleavethepartnership.Anotherfeaturethatdistinguishesdomesticationfromresourcemanagementisthecapacityofeachpartnertomakemodificationsthathelpsustaintherelationship.Forhumansthismightinvolveassessingwhetherthereturnsofamanagedresourcejustifycontinuinginvestment,especiallyinlightofthereturnsfromotheravailableresourceswhoseexploitationcarrydifferentorperhapsconflictingrequirements.Traitsthatmakeaplantoranimalresponsivetomanagementarekeyprerequisitesinasuccessfuldomesticate.Theabilitytocolonizeopen,disturbedanthropogenichabitatsisonesuchtraitinplants(14);inanimalsthesetraitsincludeahierarchicalsocialstructureand,especially,lowerreactivitytohumans(15).Anotheradaptivefeatureinasuccessfuldomesticateisthecapacityforrapidresponsetoselectivepressuresunderdomestication(geneticallydrivenorplastic)inwaysthatenhancethebenefitstheyandtheirpartnersderivefromtherelationship.Thepathwaysthathumansandtargetspeciesfollowfrominitialmanagementintodomesticationareshapedbyanumberofcontingenciesaffectingbothpartnersandcanbebroadlyclassifiedintothreetypes:(i)acommensalpathwayinwhichtheplantoranimalfirstmovesintoananthropogenichabitatandlaterdevelopsatwo-waypartnershipwithhumans,(ii)apreyorharvestpathwayinitiatedbyahumaninterestinenhancingtheyieldorpredictabilityofaresourceprovidedbytargetspecies,and(iii)adirectedpathwayinwhichhumansdeliberatelysetouttodomesticateaspecies(15).Speciesfollowingthefirsttwopathwaystendtopossessmoretraitsthatmakethemsuitablecandidatesfordomestication.Speciesondirectedpathways,incontrast,likelypossessbarrierstodomesticationthatrequiremoreknowledgeonthepartofhumanstoovercome.Thisisthepathwaytakeninallofthemorerecentdomesticationeffortswheredomesticationmayinvolvemoreadvancedtechnologies(e.g.,artificialinseminationorgeneticmanipulation).Somespecies,moreover,possessbehavioralormorphologicalcharacteristicsthatposeinsurmountablebarrierstodomestication,despitehumaneffortsatmanipulationthatinotherspeciesledtodomestication.AlthoughthereissomeevidenceoftentativestepstowardmanagementofgazelleintheearlyNeolithicofthesouthernLevant(16),forexample,theanimal’swell-developedflightreflexandresistancetocaptivebreedingprecludedtherelationshipbetweenhumansandgazellefrommovingbeyondtheinitialauditionphase(15).Onthehumansideoftheequation,potentialdomesticatesmightbeabandonedinfavorofotherequallyattractivecandidatespeciesthatsubsequentlymoveonbecometofull-fledgeddomesticates.Wildoats,barley,andemmerwheat,forexample,wereeachintensivelyusedandlikelymanagedinsomewayintheLevant,butoatslaggedfarbehindbarleyandemmerindevelopingintoadomesticate(17).Therearealsoexamplesofmultipleindependentdomesticationsofasinglespeciesfollowingverydifferentpathwaysindifferentregions(18,19).Justassomelevelofmanagementisanessentialprecursortodomestication,thepresenceofdomesticatesisaprerequisiteforagriculture.Humanutilizationofoneormoredomesticates,however,doesnotconstituteagriculture.Instead,agricultureisdistinguishedbythedegreeofdependenceondomesticates(20)andisdefinedhereas:aprovisioningsystembasedprimarilyontheproductionandconsumptionofdomesticatedresources.Notonlyaretheterms“domestication”and“agriculture”notinterchangeable,asoftenimplied(10),agricultureisnotanautomaticoutcomeofdomestication.Invirtuallyeveryinstanceofagriculturalemergencethereisalongdelayofuptoathousandyearsormorebetweeninitialdomesticationandthedevelopmentoffullyformedagriculturalsystems(20,21).Low-levelfood-producingeconomiesthatincludeamixofdomesticatesandanarrayoflooselymanagedorentirelyfree-livingresources,moreover,haveexistedformillenniawithouteverdevelopingintoagriculturaleconomies(20).Therearealsoexamplesofsocietiesthatabandonedafullyagriculturalwayoflifeinfavorofbroad-spectrumforagingstrategiespracticedhundredsofyearsearlier(22).Thereis,then,acontinuumbetweenresourcemanagement,domestication,andagriculture.Althoughtheexistenceofeachprecursorcomponentofthecontinuumisessentialforthedevelopmentofthenext,thedevelopmentofanyoneofthesedifferentphenomenadoesnotnecessarilyresultinthedevelopmentofthenext.Itisalsodifficult,alongthiscontinuumofcloselyrelatedphenomena,todrawclearandsharplydefinedthresholdsthatseparateonestagefromthenext.Howmuchinvestmentintendingaplantoranimalorhowmuchgeneticorplasticresponseonthepartoftheplantoranimalisneededbeforeitcanbesaidtohavecrossedtheboundarybetweenmanagedanddomesticated?Whatpercentageofoverallcaloricintakeandlaborinvestmentindomesticatesisneededbeforeaneconomycanbeidentifiedashavingtransitionedfromlow-levelfoodproductiontoagriculture?Focusingonprecisedemarcationofsuchthresholdsandestablishingwhen,exactly,theyhavebeencrossedisalargelyunproductiveexercisethatcreatestheerroneousimpressionofdichotomousstatesbetweenwildanddomestic,foragingandfarming,anddistractsattentionfromtheoftenopaque,butfarmoreinteresting,middle-groundareasthatliebetweenthem.Ratherthantryingtodefinesuchthresholds,itismoreproductivetoconcentrateonthecontextsandprocessesthatshapebehaviorsinvolvedinmanagement,domestication,andagricultureandtheevolutionaryprogressionbetweenthem.Thus,althoughmanagement,domestication,andagriculturehaveoverlappingelements,theyarenonethelessdistinctphenomena.Thedefinitionsproposedherefocusoncoreaspectsofeachinawaythatallowsusefuldistinctionstobedrawnbetweenthem.Management,asdefinedhere,centersontheactionsofthemanagerinattemptingtoenhancethereturnsofaresourceofinterest.Thedefinitionofdomesticationemphasizesthecoevolvingmutualismbetweenthemanagerandthemanagedresourceandtheresponseseachmaketopromotethisrelationship.Agricultureisdefinedasaprovisioningsysteminwhichtheproductionandconsumptionofdomesticatesplaysadominantrole.Definingthesecloselyrelatedtermsinthiswayspotlightsdifferentkeyfeaturesofeach,makingitclearthateachistheproductofdifferentcircumstancesinfluencedbydifferentcausalfactorsandbestmonitoredusingdifferenttypesofmarkers.ImpactsandMarkersAlthoughdomesticationshouldnotbedefinedintermsofitsimpacts,identifyingtheseimpactsandunderstandinghowtheyrelatetotheprocessofdomesticationisessential.Currentresearchondomesticationis,infact,largelyfocusedonidentifyingtheimpactsofdomesticationandusingthemasmarkersofthetimingandnaturethisevolutionarytransitioninthedistantpast,aswellastomonitorongoingeffortsatimprovingexistingdomesticatesandcreatingnewones.Domesticationproducesawidearrayofchangesthatvaryinhowdirectlytheycanbecausallylinkedtotherelationshipbetweendomesticatoranddomesticate.Establishingtheexistenceandrelativestrengthofsuchcause-and-effectlinkagesisimportantindeterminingtheutilityorvalueofdifferentmarkersusedtotracetheinitialdevelopmentandsubsequentevolutionofdomesticationpartnerships.GeneticImpacts.Geneticresponsesthatmaintainandenhancethedomesticatoryrelationshiparethemostproximateresultofdomesticationand,ifclearlylinkedtothisrelationship,areitsmostcompellingindicators.Geneticchangecanoccurinbothpartners,especiallywhennonhumanspeciesarethedomesticators.Whenhumansareinvolved,geneticchangeisalmostalwaysconfinedtotheplantoranimalpartnerspecies,withgeneticimpactsofdomesticationinhumansonlyoccasionallyidentified(23).Geneticresponsestodomesticationaretheresultofanumberofdifferentselectivepressures.Thetwomostimportantoftheseinearlydomesticatesweremostlikelytherelaxationofselectivepressuresexperiencedinafree-livingstateandtheintroductionofnewselectivefactorsarisingfromcloserassociationwithhumans(15,24).Oncehumansbegantoisolatemanagedresourcesfromfree-livingpopulations,especiallywhentheyweremovedoutsideofthenaturalrangeoftheirprogenitors,bothgeneticdriftandfoundereffectscameintoplay.Directedorartificialselectionthroughdeliberatebreedingtoencouragespecifictraitsisthoughttobearelativelylatedevelopmentinmostdomesticatesresponsiblefortheappearanceof“improvementtraits”thatfollowinitialdomestication(25).Itis,however,oftenhardtoisolateanyspecificindividualcausalfactorsthatresultinparticulargeneticresponses,withmultipleselectivepressureslikelyinvolved.Inbothplantsandanimalsthereareconstellationsoftraitsthatmaynotbetheproximateresultanyoftheselectivepressuresassociatedwiththedomesticationprocess,butareinsteadlinkedtosomeotherdirectlyselectedtrait.Inmammalsthis“domesticationsyndrome”includeslopears,mottledcoats,decreasesinbrainsize,andchangesindevelopmentalrates—alltraitsthatmayallbelinkedtostrongselectionforloweredreactivitytoexternalstimuli(15,26).Theappearanceofthispleiotropiccascadeofgeneticallydriventraitsmayresultfrommutationsinsinglegenesresponsiblefortheorchestrationofgeneexpressionduringdevelopment(27).Asaresultonlyasmallnumberofmutationsinregulatorygenesmaybeneededtoaccountformanyoftheevolutionarychangesthatseparatewildfromdomesticatedplantsandanimals.Fullgenomesequencinghasvastlyenhancedourabilitytoidentifygenesresponsibleforphenotypicchangesthatdistinguishdomesticatesfromtheirwildprogenitors,withthegreatestadvancesinvolvingtheidentificationofdomesticationgenesincropplants(28).Discoveringkeygenesresponsibleforbehavioralshiftsindomesticanimalshasprovenmoredifficult,althoughtherehavebeensomepromisingadvancesinthisdirection(29).PerhapsthemostexcitingworkindocumentinggeneticchangeassociatedwithearlydomesticationinvolvesancientDNAextractedfromarchaeobiologicalremainsandtheresultantidentificationofthetimingandsequenceoftheappearanceofkeydomesticationgenesinbothcrops(30)andlivestock(31).Themajorityofgeneticresearchondomesticationhasfocusedonneutralnoncodinggenesusedtotracethephylogenyofdomesticates.Earlyworkconcentratedonthechloroplastgenomeinplantsandmitochondrialgenomeinanimals(32).Studiesofasinglegenomeonlytellonesideofthestory,however,andmorerecentnucleargenomesequencingtechnologyhasprovidedamuchmorecompletepictureoftheheritageofdomesticates.Nucleargenomeresearch,forexample,hasdemonstratedthatwhatseemedtobemultipleindependentdomesticationeventsinvariouslivestockspeciesaremorelikelyattributabletointrogressionbetweenintroduceddomesticatesandindigenouswildpopulations(25).OnceagainthemostsignificantinsightsintothephylogeniesofdomesticatesaregainedthroughtheanalysisofancientDNA,whichpromisesapictureoftheearlydivergenceofdomesticatesfromwildprogenitorsuncloudedbythemillenniaofsubsequentintrogressionanddirectedbreeding(25,33).PhenotypicImpacts.Geneticallydrivenphenotypicchangesinmorphology,physiology,orbehaviorofemergentdomesticatesareonestepremovedfromtheselectivefactorsoperatingonthegenomesofdomesticates.Asaresultthereisasomewhathigherburdenofproofindeterminingwhetherspecificphenotypictraitsindomesticcropsandlivestockare,infact,theproductofthedomesticatoryrelationshipand,ifso,howandwhentheyarose.Thechallengesinusingthesetraitstotracedomesticationpathwaysarecompoundedbythefactthatonlyasmallportionofthephenotypicimpactsofdomesticationarevisibleinthearchaeologicalrecord.Inannualplantsimpactsofdomesticationareseenprimarilyintraitsrelatedtogerminationanddispersal—changesindormancyrates,seedsize,andtestathickness,aswellasinthetimingandmorphologyofdispersalmechanisms(14,34).Ithadbeenthoughtthatthatthemostarchaeologicallyvisibleimpactsofdomesticationinsomeannualplants(i.e.,seedsizeincreasesandthelossofindehiscentstructuresforseeddispersal)wouldappearquitequicklywithsustainedhumansowingandharvesting(35).Recentwork,however,hasshownthattheseresponsesmayappearsubstantiallylaterthanotherphenotypicchanges.TheappearanceofnonshatteringrachisesinNearEasterncereals,forexample,isnot,asonceargued,amarkerofthebeginningofadomesticatoryrelationshipwithhumans,butinsteadanartifactofchangesinharvesttechnologyandtimingthatoccurredlongafterhumanswereactivelyengagedinsowing,cultivating,andharvestingcereals(34).RecentevidencealsoindicatesthatseedsizeincreaseinNearEasternpulsesonlyappearedafterotherresponsestohumancultivationoccurred—theloweringofseeddormancyratesandthedevelopmentofindehiscentseedpods,attributesthatinpulsesarenotgenerallypreservedinarchaeobiologicalassemblages(36).Incontrasttoannualplants,ithasbeenarguedthatdeliberateselectionfordesiredtraitsplayedasignificantearlyroleinthedomesticationofperennialplantsandtreespecies,especiallythoseclonallypropagatedthroughvegetativecuttings(14,37).Phenotypicresponsesinrootcropsandtubers,forexample,arearguedtoincludechangesinthesize,chemical,andstarchcompositionofundergroundorgansthatmadetheseplantsmorepalatableandmoreprofitable(38).Intheabsenceofdecay-resistantdiagnosticparts,especiallyinthehumidtropicswheremanyofthesecropswerefirstdomesticated,researchhasfocusedontherecoveryofstarches,whichseemtodisplaydistinctivephenotypicresponsestodomesticationinbothmorphologyandtheirsize(38).Althoughhighlysusceptibletopostdepositionaldecay,starchescanberecoveredfromthesurfaceandinterstitialcracksinchippedandgroundstoneandpotteryandeveninthecalculusonhumanteeth(39).Phytolithsareanothermicroscopicplantcomponentarguedtohaveundergonegeneticallydrivenphenotypicchangeunderdomestication.Foundinmanyannualandperennialcropplants,theseopalsilicabodiesprovidestructuralsupport,protectagainstpredation,andarehighlyresistanttopostdepositionaldecayundermostconditions(40).Aswithstarches,itisarguedthatthereisadirectrelationshipbetweenselectionforlargerfruitsizeandanincreaseinphytolithsize,sometimesaccompaniedbydistinctivechangesinmorphology—traitsusedasmarkersofdomesticationinanumberofcropplants(41⇓–43).Theutilityofmicrobotanicalremainssuchasstarchesandphytolithsasmarkersofdomesticationistemperedbyanumberoffactors.Theseincludealackofclarityaboutthelinkagebetweenselectionforcesonplantsunderdomesticationandobserveddifferencesinthesizeandmorphologyofstarchesandphytoliths(40),aswellasdifficultyindistinguishingdomesticationtraitsfromthosecausedbyfactorsunrelatedtodomestication(i.e.,pathogens,soilsubstrate,wateravailability,andfoodpreparationtechniques)(44⇓⇓–47).Taphonomicissuessurroundingthepreservationandstratigraphicintegrityofplantmicrofossilsarenotwellunderstood(48).Uncertaintiesaboutthemovementofphytolithsinsoils,inparticular,raisequestionsaboutthereliabilityofindirectdatesofphytolithsrecoveredfromarchaeologicaldeposits,andevendirectradiocarbondatingofphytolithsmaybeaffectedbythesequestrationofoldcarboninphytoliths(49).Inconsistenciesinthedescriptionandquantificationofdistinguishingcriteria,especiallyuncertaintyoverinter-andintrataxavariability(48,50),arecitedasseriousconcernslimitingtheutilityandreliabilityofmicrofossilsindocumentingdomesticationthatcallformoreconscientiouspublicationofimagesofreferencecollectionsandarchaeologicalassemblages(48)andfreeraccesstoassemblagesbyresearchersseekingtoreplicateresults.Inanimalstheearliestandmostuniversalgeneticallydrivenphenotypicimpactsofdomesticationfocusonbehavioralattributes,especiallyonendocrine-controlledbehaviorsthatlowertheanimal’sreactivitytohumansandfacilitateitsadaptationtoananthropogenicenvironment(15).Theseselectivepressuresarearguedtoresultinbrainsizereductionindomesticanimals(51),especiallyinthoseareasofthebraincontrollingendocrinefunction,that,asdiscussedabove,arelinkedtopedomorphismindevelopmentalratesandtheretentionofjuvenilemorphologicalcharacteristicsinadultanimals(15).Theneotonizationofdomesticpiganddogcranialmorphologyattributedtothisprocessisarguedtohavecausedadecreaseinprognathismthat,inturn,isresponsibleforreductioninthesizeofteeth,crowding,andvariationsintoothnumber—traitsusedasmarkersofinitialdomesticationinthesespecies(52,53).Itmaybedifficult,however,totellwhetherthesetraitsaroseduringaninitialcommensalphaseastheseanimalsmovedintoanthropogenicniches,ratherthanasresponsestoalaterphaseofactivedomestication.Oncethoughtamarkerofinitialdomesticationinsheepandgoat,changesinhornmorphology—linkedtoarelaxationoftheselectiveadvantageoflargehornsinmatecompetition,activeselectionagainstlargehornsnolongerusefulinsecuringmates,andperhapsdeliberatedirectedselectionbyhumansagainstaggressivelarge-hornedmales—arenowknowntohaveappearedafterdomesticatesweremovedoutofthenaturalhabitatoftheirwildprogenitors,amillenniaormoreafterclearsignsthattheseanimalsweremanagedinwaysconsistentwithdomesticherds(54).Theutilityofbodysizereduction,onceconsideredanessentiallyinstantaneousproductofdomestication(55),hasalsobeencalledintoquestion.Apparentdecreasesinovi-capridbodysizeatabout10,000yagoarenowknowntobetheresultofdemographicshiftsinthearchaeologicalassemblagesofmanagedanimals(dominatedbysmallerfemales)comparedwithassemblagescomposedofhuntedanimals(dominatedbylargeprime-agemales)(56).Geometricmorphometrics(GMM)isarelativelynewandwidelyheraldedtechniquefordistinguishingbetweentheteethofwildanddomesticpigs(31,57⇓–59).Ratherthantheresultofspecificselectivepressures,itisarguedthatsubtlechangesintoothshapemeasuredbyGMMareproxiesfortheneutralgeneticshiftsusedtotracethephylogenetichistoriesofdomesticanimals(18).Demonstrationisstilllacking,however,ofhowandwhythesechangesintoothshapetrackthegeneticdifferentiationbetweenwildanddomestictaxa(60).Ifshapecantobeshowntobeamarkerofphylogeny,thenextchallengewillbetodeterminehowphylogeneticdifferentiationcausedbydomesticationcanbedistinguishedfromotherprocesses,(i.e.,geographicbarriersorhabitatshifts)thatalsoresultinreproductiveisolationandsubsequentgeneticdifferentiation.Aswithplantmicrofossils,issuesofinteranalystcomparability,quantification,andstandardizationneedtobeaddressedbeforethepotentialofGMMindocumentingdomesticationcanbefullyrealized.PlasticImpacts.Domesticationalsoresultsinplasticresponsesunrelatedtogeneticresponsestothenewselectivepressuresexperiencedunderdomestication,ortheirphenotypicexpression.Nonetheless,plasticresponsestodomesticationmaybebothnumerousanddramaticand,asaresult,canprovidesignificantinformationregardingthedomesticationprocess.Inhumans,these“ecophenotypic”responsesinclude:contractionofzoonoticdiseasescarriedbydomesticanimals;changesinstatureorgrowthrates;increasedprevalenceofdentalcariesowingtogreaterrelianceoncarbohydrate-richcropplants;changesinbonechemistryreflectingdietaryshifts;andbiomechanicalstressesonhumanskeletonsfromtendingdomesticates(61).Inanimalsproposeddomestication-inducedplasticresponsesinclude:dentalirregularities(hypoplasias)causedbynutritionalandotherstressesexperiencedunderhumanmanagement;diseasesthatcauselargefetalandneonatalmortality;bonechemistrychangesowingtoprovisionofforageorchangesinthemobility;andpathologiesarisingfromtethering,useasdraftanimals,riding,orcarryingheavyloads(62⇓⇓–65).Plasticresponsesinplantsthatariseasaconsequenceofhumancultivationarefewerandincludepossibleresponsestoartificialwateringthatincreasetheplumpnessofcerealgrainsoraffectthesizeandaggregationofphytoliths,aswellaschemicalresponsestofieldconditions(66⇓–68).Thelinkageofplasticresponsestodomestication,however,ismoredifficulttodifferentiatefromothercausalfactorsunrelatedtodomestication.Itisalsodifficulttoidentifyatwhatpointtheseresponsesbecomemanifest,withmanyarisingafterdomesticatesbecometheunderpinningsofagriculturaleconomies.ImpactsonNaturalandCulturalContexts.Impactsofdomesticationarealsoseeninthenaturalandculturalsettingsinwhichtheevolvingrelationshiptakesplace.Humanniche-constructingactivitiesdirectedatenhancingtheyieldorpredictabilityofresourcesofeconomicinterestthatareprerequisitesfordomesticationmayhaveprofoundimpactsonnaturalenvironments.Theseactivitiesinclude:modifyingvegetativecommunitiesthroughburningtoincreaseabundanceofherbaceousplantsandanimalsofeconomicimportance;modifyinglandscapestoenhancewaterdeliveryorexpandhabitatzonesofplantsandsessileanimals;broadcastsowingofwildannualsnearwatersources;transplantingperennialfruit-bearingspeciesnearertosettlements;andselectivelycullingcompetingvegetationtoencouragethegrowthoffruit-andnut-bearingtrees(69,70).Increasesintheabundanceofananimalspeciesinthearchaeologicalrecordmayresultfromeffortsthatpromotepopulationgrowth(i.e.,burning),orthroughtheconstructionofstructuresthatfacilitatecapture(i.e.,fishweirsorkites)(69,71).Effortsatenhancingaccesstoeconomicallyimportantanimalsalsofindexpressioninharveststrategiesdesignedtoincreasepreyavailabilitythatmayleadtoactivemanagementofanimalpopulationsanddomestication(54,56).Evolvingrelationshipsbetweenhumansandtargetplantandanimalspeciesalsohaveenduringimpactsontheculturalsettinginwhichtheserelationshipsdeveloped.Tendingplantsandanimalsandstoringresourcestheyproducemayfindexpressioninthebuiltenvironment(appearanceofcorrals,storagepits,orsilos,thepresenceofmanureanditsuseasafuelorbuildingmaterial)thatmaybeusedtotracetheincreasinglycloserelationshipsbetweenhumansandmanagedresources(72,73).Greaterinvestmentinresourcemanagementmaystrengthennotionsofownershipoverresourcesandthecatchmentareasinwhichtheyaregrownandharvested,resultinginmoretightlydefinedanddefendedterritories(74).Alterationsinlaborrelations,inaccesstoresourceswithincommunities,inmechanismsformaintainingcommunitycohesion,andeveninbeliefsabouttherelationshipbetweenhumansandthenaturalworldhaveallaccompaniedincreasinghumaninvestmentinemergentdomesticatesinwaysthathavefoundexpressioninthearchaeologicalrecord(75).Impactsonnaturalandculturalsettings,however,maybeespeciallyhardtolinktodomestication.Theeffectsofresourcemanagementonnaturalsettingsaredifficulttodetectand,ifdetected,difficulttodistinguishfromnaturalforces(70).Argumentsforhumaninvolvementinthemovementofdomesticatesbeyondthegeographicalrangeoftheirwildprogenitorsbasedonmoderndistributionsmaynotreliablyreflectancientdistributions(54,76).Culturalresponsestoincreasingengagementinmanagingplantsandanimalsmayvaryandmayariseintheabsenceofdomesticates.Whereasmanyofthearchaeologicalmarkersresultingfromtheseimpactscanbeusedtodetectresourcemanagement,theyarenotnecessarilyindicativeofthedevelopmentofadomesticatoryrelationshipbetweenhumansandmanagedspecies.Thisrequiresdemonstratingtheexistenceofasustainedcoevolvingmutualismbetweenhumansandtargetspecies.Thisisnottosaythatevidenceofgeneticorresultingphenotypicchangenecessarilytakespriorityoverothermarkers.Thedetectionof“domestication”genescontrollingcoatcoloramongpigsrecoveredfromforagersettlementsinnorthernEurope,forexample,doesnotindicatethatthesehunter-gatherers“possessed”domesticpigsorthatthesewere“theearliestdomesticanimals”inthisregion(57,77).Rather,itindicatesthatthesepigshadsomedegreeofdomesticancestry,likelyacquiredthroughintrogressionbetweenescapeddomesticpigsfromnearbyfarmingcommunitiesandindigenouswildboar(60,78).Inadditiontogeneticmarkers,establishingthedomesticstatusoftheseanimalswouldrequiresomeevidencethatforagerswereengagedinanongoingdomesticatoryrelationshipwiththepigsinquestion,basedon,forexample,harvestprofiles,evidenceofpenning,ornutritionalchangesindicativeofactivehumanmanagement.Noonemarker—genetic,phenotypic,plastic,orcontextual—issufficienttodefinitivelydocumentdomestication.Becausedomesticationisamultifacetedrelationshipinvolvingbothbiologicalandculturalprocesses,documentingitrequireslookingacrossawiderangeofmarkersandtrackinghowandwhentheyaremanifested.Fortunately,methodsfortracingmultiplemarkersofdomesticationupthroughtimehavebeendevelopingatarapidpaceand,asaresult,therearenowrelativelyhigh-resolutionrecordsoftheoriginsandevolutionofplantandanimaldomesticationinanumberofworldareas.Theseincreasinglydetailedregional-scaledevelopmentalsequencesaremakingitpossibleforresearcherstobetteraddressthemostdifficultofthecorequestionsofdomesticationresearch:whytheserelationshipsaroseinthefirstplace.CausalFactorsEarlycausalexplanationsfordomesticationconflateddomesticationandagriculture,andfocusedonidentifyingsinglefactorsthatwerethoughttoaccountforbothphenomena(79).These“prime-mover”explanationscanbegroupedinto“push”and“pull”scenarios.Pushscenariossetdevelopmentsinthecontextofexternalstressesthatforcedpeopletodomesticateandadoptagriculturalpractices—factorssuchasclimatechangeorpopulationincrease.Pullscenarioswereusuallysetinmorebenign,evenbountiful,contexts,emphasizinginternalfactorsthatencouragedhumanstoadoptthesepractices—aninterestinsocialpromotionorcognitivechangesinhowpeopleviewtheirrelationshiptothenaturalworld(75).Suchsingle-factorscenarioswereeasiertoadvancewhentheoutlinesofdomesticationandagriculturaloriginsinvariousworldareaswerepoorlydocumented.Thehigh-resolutionregional-scalerecordsthatarenowbecomingavailable,however,indicatethatthesedevelopmentswereshapedbyanumberofcomplexandlocallycontingentfactorsthatcannotbeaccountedforbysingle-factorexplanatoryframeworks(79).Asaresult,attentionhasshiftedtowardidentifyingbroadercontextualframesofreferencewithinwhichdifferentregionaltrajectoriesofdomesticationandagriculturehaveunfolded.Thelongdelaybetweeninitialdomesticationandthedevelopmentofagricultureindifferentindependentregions(20,76)alsomakesitclearthatasingleexplanatoryframeworkcannotaccountforboththeoriginsofdomesticationandthesubsequentemergenceofagriculture.Althoughthedescriptivegloss“originsofagriculture”or“OA”issometimesstillused(10),almostallcurrentresearchisfocusednotonagriculturaloriginsbutoninitialdomestication(76).Twoalternativeexplanatoryframeworksforinitialdomesticationhaverecentlydrawnconsiderableattention.Althoughbotharecharacterizedasgroundedinevolutionarybiology,theydrawonverydifferentparadigmsandofferoppositionalexplanatoryaccounts.Foroveradecaderesearchersendorsingoptimalforagingtheory(OFT)havearguedthatgoalsofoptimizingenergeticreturnswereprimaryshapingfactorsindomestication(80⇓⇓–83).Characterizedasderivedfromneo-Darwinianevolutionarytheory,OFTisbasedonthepremisethatoptimizingbehaviorsconferaselectiveadvantagetoindividualswhopracticethem.OfthevariousOFTmodelsthathavebeendeveloped,onlythedietbreadthmodel(DBM)hasbeenusedineffortstoexplaininitialdomestication(10).DBMpredictsthatforagerswillalwayschooseresourceswithhighernetenergyreturns,aftersearchandprocessingcosts,overlowerreturnresources.Itemsareaddedtothedietindescendingrankorder,withitemsfallingbelowacertainlevelofreturnalwaysignored,regardlessoftheirabundance,aslongasthereisareasonableexpectationoftheavailabilityofhigher-rankedresources.Themodelfurtherpredictsthatwhenhigh-rankingresourcesareabundant,dietbreadthwillnarrowandforagingefficiencywillincrease.Conversely,whenavailabilityofhigh-rankedresourcesdecreases,dietbreadthwillbroadenbecauseawiderrangeoflower-rankedresourceswillbeaddedtothediettocompensateforreducedaccesstohigher-rankedresources,resultinginanoverallloweringofforagingefficiency.Moreover,underDBMrulesforagerswillonlyoptforresourceswithdelayedreturns(resourcesthatrequiretendingoveragrowthcycle)whenresourcesthatprovideimmediatereturnsarenolongerasplentiful.BecausedomesticationfrequentlyfocusesonresourcesOFTproponentsidentifyaslow-ranking—plantsandsmalltomedium-sizemammals(10)—theadditionofprogenitorsoffuturedomesticatestoforagerdietsisautomaticallycastasaresponsetoloweredavailabilityofhigher-rankingresources(i.e.,largergameanimals).Moreover,becausemanagementoftheseresourcesentailsasystemofdelayedreturns,theimpetusforincreasingengagementinmanagementisalso,bydefinition,aresponsetocontinuedresourcepressurethatprecludesareturntotheimmediate-returnstrategiesfocusedonhigh-rankedresources.SuchDBM-derivedexplanationsforinitialdomesticationrepresentarecentincarnationofstress-basedor“push”prime-movermodels,providingaframeworkinwhichresourcedepression,environmentallyordemographicallyinduced,accountsfortheadditionofdomesticateprogenitorsintothedietandtheirsubsequentdomestication.IndirectoppositiontoDBM-basedexplanatoryframeworks,aculturalnicheconstruction(CNC)explanatoryframeworkforinitialdomesticationisdirectlyderivedfrommacroevolutionarytheory(69,74,76,84⇓–86).Incontrasttoaneo-Darwinianfocusonselection-drivenallelefrequencychangesinindividualorganisms,macroevolutionarytheoryconsidersorganismsasintegratedwholesthatdonotsimplyadapttochangesintheirenvironmentbutthatmay,throughmorehierarchicalandinteractiveprocesses,actuallyshapetheirenvironments(23).Thisisaccomplishedthroughnicheconstructionorecosystemengineering,withorganismsacting“asco-directorsoftheirownandotherspeciesevolution”(87).Althoughmanyorganismsengageinniche-constructingactivities,humans,withtheirabilitytospontaneouslyinventandmodifynewgoal-directedbehaviorsandpassthemonthroughculturaltransmission,areconsideredthe“ultimatenicheconstructors”(84,88).ThesearethebehaviorsthatCNCexplanatoryframeworksholdcentraltothedomesticationofplantsandanimals.WhereasOFTexplanatoryframeworkscasteffortsatmodifyingenvironmentsleadingtodomesticationasadaptiveresponsestoresourcedepression(81,83),CNCexplanatoryframeworksseenicheconstructionasanimportantdriverofevolutionarychangethatdoesnotrequireresourcedepressiontobesetintomotion.Infact,aCNCapproacharguesthatlong-termcommitmentstoniche-constructingactivitiesrequiredfordomesticationaremorelikelytooccurinstableorresource-richenvironments(76,86).So,whereasOFTscenariosplacedomesticationinthecontextofimbalancesbetweenpopulationandaregion’scarryingcapacity(10),CNCexplanatoryframeworksarguethatstabletoresourcerichenvironmentsmadeitpossibleforhumangroupstoabandonmoremobilestrategiesandestablishrelativelypermanentcommunitiesthatservedasthenexusfortheincreaseanddisseminationofinformationabouttheenvironment,eachother,andthebroaderworld(86).Environmentswithabundant,diverseresourcespredictablyfoundwithinwell-definedresourcecatchmentterritoriesprovidedparticularlyproductiveplatformsforthedevelopmentofbroad-basedsubsistenceeconomiescapableofsupportinglargerandmorepermanentcommunities.Stable,resource-richenvironmentsalsoprovidedopportunitiesforexperimentationwithdifferentproductivity-enhancingexploitationtechniques(74,86).Atthesametimeotherspeciestookadvantageofnewlycreatedanthropogenicniches,fosteringnewrelationshipswithhumans.Long-terminvestmentintheseenvironmentsservedasanaddedincentiveforhumangroupstodefendresourcecatchmentterritoriesandcontinuetoenhancethegrowingstoreofecologicalknowledgethatallowedcommunitiestocontinuetoreaptherewardsofpreviousgenerations’investmentinmodifyingandshapingtheseenvironments(74).CNCexplanatoryframeworksaresimilarinsomerespectstoearlierpullscenariosinthat,incontrasttoDBMexplanations,theyincludeanimportantsocialelement—althoughinthiscaseforcesenhancingsocialcohesionareemphasizedoverthosethatpromotedifferentialaccesstoresources.However,unlikeearlierpullexplanationsthattendtocastsocialandideologicalfactorsassoledriversoftheprocessattheexpenseofenvironmentaloreconomicconsiderations,aCNCapproachdemonstrateshow,inthecontextofresource-richenvironments,goalsofpreservingcommunitycohesionandlongevitycombinewithcomplementarygoalsofcreatingasecureandpredictableresourcebase,producingnaturalandculturalcontextsinwhichniche-constructingactivitiesleadtothedevelopmentofdomesticatoryrelationshipsbetweenhumansandtargetplantandanimalspecies.OFT-derivedexplanatoryframeworksfordomesticationhaverecentlybeencharacterizedassuperiortootherexplanatoryapproachesbasedontheirsupposedpurerscientificpedigreeandtheshortcomingsofalternatives,includingthosederivedfromniche-constructiontheory,whicharedescribedasa“hodgepodge”ofinductivelyderivedparticularisticjust-sostoriesthatrepresenta“retreatfromtheory”(10).ExplanationsderivedfromDBMarecharacterizedasprovidingcompellingaccountsfor“agriculturalorigins”(initialdomestication)thatarewellsupportedbyempiricaldataintwooftheworld’sindependentcentersofdomestication,theNeotropicsandsouthwestAsia.AthirdcenterwhereDBMisacknowledgedasfailingtoexplaindomestication,easternNorthAmerica,isarguednonethelesstobeinaccordancewithothermodelsbasedoncoreOFToptimizingprinciples.Closerscrutiny,however,showsthatDBM/OFTexplanatoryframeworkslackempiricalsupportinallthreeofthesecentersofdomestication(76,79,86).IntheNeotropics,forexample,climate-inducedresourcedepressionintheformoflatePleistocenemegafaunalextinctionisidentifiedasforcinghumanforagerstoadaptbyexpandingtheirdiettoincludelower-rankingrootcrops,whichwerethendomesticated(83).Recentresearch,however,indicatesthatmegafaunadisappearedfromnorthernSouthAmericaafull3,000ybeforeinitialhumanoccupationoftheregion,and5,000ybeforetheearliestevidencefordomesticates(76,89).Inaddition,aproposednorthernSouthAmericacenterofdomesticationofmorethanadozenrootcropsissituatednotinthesavanna/dryshrubenvironmentofPleistocenemegafauna,butratherintheseasonaldryforestsofinter-Andeanrivervalleys—environmentsthatdidnotwitnessanyapparentdeclineinresourceavailabilityleadinguptoinitialdomestication(76,90).Similarly,DBM-basedexplanationsfortheincreaseindietarydiversityandresourceintensificationleadinguptoinitialdomesticationintheLevantineregionofsouthwestAsiaarebasedontroublingtautologiesthatinterpretthelossofmobilityasevidenceforthecausalroleofpopulationpackinginthelossofmobility,andthediversificationinthedietaryresourcesasanindicationoftheroleofresourcedepressionincausingresourcediversification(81,91).IntheeasternareasoftheFertileCrescentwherethreemajorlivestockspeciesandanumberofcropplantswereinitiallydomesticated(21),evenOFTproponentsadmitthatthereisnoevidenceforeitherpopulationpackingorresourcedepression(92).Finally,claimsthatOFTpractitionershaveengagedinarigorous“hypothetical-deductive”programof“theoreticallydrivenhypothesistesting”ineasternNorthAmerica,whereDPMpredicationsarenotsupportedbyempiricaldata(10,82),areinsteadexamplesofposthoctheorizinginwhichoneOFT-derivedmodelisreplacedwithanotherwithoutfurthertestingorconsiderationofothermodelsthatlieoutsideOFToptimizingprecepts(76).However,thereisabundantevidencethatwouldsupportalternativeCNC-informedexplanatoryframeworksforinitialdomesticationinallthreeregions(76,79,86).Initialdomesticationineachtakesplaceinthecontextofforagingcommunitiessituatedinrivervalleycatchmentswitheasyaccesstomultipleecozonessupportinganarrayofabundantandpredictablyavailableresources.Thereisalsoampleevidenceforaprotractedperiodofhumanenhancementofenvironmentsthatprecededinitialdomesticationineachregion—evidenceofanthropogenicfiresresultinginshiftsinforestcomposition,aswellasincreasedavailabilityofhigh-valueplantandanimalspeciesthatmovedintonewlycreatedanthropogenicenvironments(76,82,90,93⇓–95).Therelativevalueofthesetwoverydifferentexplanatoryapproachestoinitialdomesticationcannowbedeterminedthroughside-by-sidecomparisoninanexpandingnumberofworldareaswhereenhancedmethodsfortrackingtheimpactsofevolvingdomesticatoryrelationshipsareproducingdetailedempiricalrecordsoftheseevolutionarytransitions(76,86).Advancingourunderstandingofthecausalcontextofdomestication,however,willbebasedonconscientiouscomparisonofalternativeexplanatoryframeworkswithempiricalreality,ratherthanthepolemicsandposturingthatoftenaccompanythedefenseoffavoredparadigms.RelevanceAfinalquestiontobeaddressediswhetherdefiningdomestication,identifyingitsimpacts,andexploringthereasonswhyhumansandcertainplantandanimalspeciesfirstenteredintodomesticatoryrelationshipshasanyrelevancetocurrentpressingissuesconcerningdomesticatesandtheirroleinfeedingtheworld’sgrowingpopulations.Theansweris,quitesimply,yes.Understandinghowplantandanimalspeciesrespondtovaryinglevelsofhumanmanipulationisdirectlyrelevanttoongoingeffortsatimprovingexistingcropsandlivestockandbringingnewandevermorechallengingspecieswithgreaterinnatebarrierstodomesticationunderhumancontrol.Tracingthepathwaythathumanstooktobecomeprimarydriversofearthsystems,usheringintheAnthropocene,beginswithhumaneffortsatecosystemengineeringthatledtoinitialdomesticationofplantsandanimalsmorethan10,000yagoandcreatedtheplatformfortheagriculturaleconomiesthathavetransformedEarth’sbiota,landforms,andatmosphereandthetrajectoryofhumanculturalevolution(96).Alookbackwardatthewaysinwhichhumansandtheirdomesticatepartnerscreatedanthropogeniclandscapesthatbothsustainedandenhancedecosystemsaroundtheworldand,attimes,renderedthemuninhabitablefororganismslivingoutsidehumanecoengineeredsystems,hasdirectrelevanceforunderstandingpresent-dayissuesofsustainabilityandbiodiversityloss.Finally,exploringcoreconceptsofdomesticationprovidesanunparalleledopportunitytoexaminetheinterfacebetweenhumansandthenaturalworldandhowprocessesthatshapehumanculturalevolutioninteractwiththosegoverningbiologicalevolution.Achievingthefullpotentialofdomesticationresearchrequiresabroadlytransdisciplinaryapproachthatbringstogethergenetics,evolutionarybiology,ecology,andanthropologyinwaysthatpromiseexcitingnewinsightsregardingthecoevolutionofcoupledhumanandnaturalsystems.Askingthefundamentalquestionsaboutdomesticationaddressedhere—whatitis,whatisdoes,andwhyithappens—providesaunifyingframeworkthatgroundsdiverseandfar-rangingresearchreachingfromtheinitialstepshumanandplantandanimalpartnersfollowedintodomesticatoryrelationshipsuptothepresentdayandbeyond.AcknowledgmentsIthankGaryCrawford,EdwårdFisher,FionaMarshall,andBruceSmithforhelpfulcommentsonthispaper.Footnotes↵1Email:zederm{at}si.edu.ThiscontributionispartofthespecialseriesofInauguralArticlesbymembersoftheNationalAcademyofScienceselectedin2012.Authorcontributions:M.A.Z.designedresearchandwrotethepaper.Reviewers:G.W.C.,UniversityofTorontoMississauga;andF.B.M.,WashingtonUniversityinSt.Louis.Theauthordeclaresnoconflictofinterest.Thisarticlecontainssupportinginformationonlineatwww.pnas.org/lookup/suppl/doi:10.1073/pnas.1501711112/-/DCSupplemental. References↵ErvynckA,DobneyK,HongoH,MeadowR(2001)Bornfree!:NewevidenceforthestatusofpigsfromÇayönüTepesi,EasternAnatolia.Paléorient27(2):47–73.OpenUrlCrossRef↵O’ConnorT(1997)Workingatrelationships:Anotherlookatanimaldomestication.Antiquity71(271):149–156.OpenUrl↵RindosD(1984)TheOriginsofAgriculture:AnEvolutionaryPerspective(Academic,Orlando,FL).↵FullerD,AllabyR,StevensC(2014)Domesticationasinnovation:Theentanglementoftechniques,technologyandchanceindomesticationofcerealcrops.WorldArchaeol42(1):13–28.OpenUrl↵TerrellJ,etal.(2003)Domesticatedlandscapes:Thesubsistenceecologyofplantandanimaldomestication.JArchaeolMethodTheory10(4):323–368.OpenUrlCrossRef↵HiggsE,JarmanM(1969)Theoriginsofagriculture:Areconsideration.Antiquity43(169):31–41.OpenUrl↵HeckerH(1982)Domesticationrevisited:Itsimplicationsforfaunalanalysis.JFieldArchaeol9(2):217–236.OpenUrlCrossRef↵SchultzT,MuellerU,CurrieC,RehnerS(2005)Reciprocalillumination:acomparisonofagricultureinhumansandinfungus-growingants.EcologicalandEvolutionaryAdvancesinInsect-FungalAssociations,edsVegaF,BalckwellM(OxfordUnivPress,NewYork),pp149–190.↵BoydR,RichersonPJ(1985)CultureandEvolutionaryProcess(UnivofChicagoPress,Chicago).↵GremillionKJ,BartonL,PipernoDR(2014)Particularismandtheretreatfromtheoryinthearchaeologyofagriculturalorigins.ProcNatlAcadSciUSA111(17):6171–6177.OpenUrlAbstract/FREEFullText↵ZederM(2006)Centralquestionsinthedomesticationofplantsandanimals.EvolAnthropol15(3):105–117.OpenUrlCrossRef↵IngoldT(1996)Growingplantsandraisinganimals:Ananthropologicalperspectiveondomestication.TheOriginsandSpreadofAgricultureandPastoralisminEurasia,edHarrisD(SmithsonianInstitution,Washington,DC),pp12–24.↵Odling-SmeeFJ,LalandK,FeldmanM(1996)Nicheconstruction.AmNat147(4):641–648.OpenUrlCrossRef↵SmithBD(2006)Documentingplantdomesticationinthearchaeologicalrecord.DocumentingDomestication:NewGeneticandArchaeologicalParadigms,edsZederM,EmshwillerE,SmithBD,BradleyD(UnivofCaliforniaPress,Berkeley,CA),pp15–24.↵ZederM(2012)Thedomesticationofanimals.JAnthropolRes68(2):161–190.OpenUrlCrossRef↵Rowley-ConwyP,LaytonR(2011)Foragingandfarmingasnicheconstruction:Stableandunstableadaptations.PhilosTransRSocLondBBiolSci366(1566):849–862.OpenUrlAbstract/FREEFullText↵WeissE,KislevME,HartmannA(2006)Autonomouscultivationbeforedomestication.Science312(5780):1608–1610.OpenUrlAbstract/FREEFullText↵OttoniC,etal.(2013)Pigdomesticationandhuman-mediateddispersalinwesternEurasiarevealedthroughancientDNAandgeometricmorphometrics.MolBiolEvol30(4):824–832.OpenUrlAbstract/FREEFullText↵LeeG-A,CrawfordGW,LiuL,SasakiY,ChenX(2011)Archaeologicalsoybean(Glycinemax)inEastAsia:Doessizematter?PLoSONE6(11):e26720.OpenUrlCrossRefPubMed↵SmithB(2001)Lowlevelfoodproduction.JArchaeolRes9(1):1–43.OpenUrlCrossRef↵ZederM(2011)TheoriginsofagricultureintheNearEast.CurrAnthropol54(S4):S221–S235.OpenUrl↵Rowley-ConwyP(2013)Northofthefrontier:EarlydomesticanimalsinnorthernEurope.TheOriginsandSpreadofDomesticAnimalsinSouthwestAsiaandEurope,edsColledgeS,ConolloyJ,DobneyK,ManningK,ShennanS(LeftCoast,WalnutCreek,CA),pp283–312.↵O’BrienM,LalandK(2012)Genes,culture,andagriculture:Anexampleofhumannicheconstruction.CurrAnthropol53(4):434–470.OpenUrlCrossRef↵MarshallFB,DobneyK,DenhamT,CaprilesJM(2014)Evaluatingtherolesofdirectedbreedingandgeneflowinanimaldomestication.ProcNatlAcadSciUSA111(17):6153–6158.OpenUrlAbstract/FREEFullText↵LarsonG,FullerD(2014)Theevolutionofanimaldomestication.AnnuRevEcolEvolSyst45:115–136.OpenUrlCrossRef↵WilkinsAS,WranghamRW,FitchWT(2014)The“domesticationsyndrome”inmammals:Aunifiedexplanationbasedonneuralcrestcellbehaviorandgenetics.Genetics197(3):795–808.OpenUrlAbstract/FREEFullText↵JensenP(2006)Domestication-Frombehaviortogenesandbackagain.ApplAnimBehavSci97(1):3–15.OpenUrlCrossRef↵DoebleyJF,GautBS,SmithBD(2006)Themoleculargeneticsofcropdomestication.Cell127(7):1309–1321.OpenUrlCrossRefPubMed↵CarneiroM,etal.(2014)Rabbitgenomeanalysisrevealsapolygenicbasisforphenotypicchangeduringdomestication.Science345(6200):1074–1079.OpenUrlAbstract/FREEFullText↵FonsecaR,etal.(2015)TheoriginandevolutionofmaizeinthesouthwesternUnitedStates.NaturePlants,10.1038/nplants.2014.3.↵GirdlandFlinkL,etal.(2014)EstablishingthevalidityofdomesticationgenesusingDNAfromancientchickens.ProcNatlAcadSciUSA111(17):6184–6189.↵ZederMA,EmshwillerE,SmithBD,BradleyDG(2006)Documentingdomestication:Theintersectionofgeneticsandarchaeology.TrendsGenet22(3):139–155.OpenUrlCrossRefPubMed↵LarsonG,BurgerJ(2013)Apopulationgeneticsviewofanimaldomestication.TrendsGenet29(4):197–205.OpenUrlCrossRefPubMed↵FullerD,AllenbyR(2009)Seeddispersalandcropdomestication:Shattering,germinationandseasonalityinevolutionundercultivation.AnnualPlantReviews38:238–295.OpenUrl↵HillmanGC,DaviesMA(1990)Domesticationratesinwildwheatsandbarleyunderprimitivecultication.BiolJLinnSocLond39(1):39–78.OpenUrlCrossRef↵TannoK,WilcoxG(2006)TheoriginsofcultivationofCicerarietinumL.andViciafabaL.:EarlyfindsfromTellel-Kerkh,north-westSyria,late10thmillenniumB.P.VegHistArchaeobot15(3):197–204.OpenUrlCrossRef↵ZhengY,CrawfordGW,ChenX(2014)Archaeologicalevidenceforpeach(Prunuspersica)cultivationanddomesticationinChina.PLoSONE9(9):e106595.OpenUrlCrossRefPubMed↵PipernoDR,RanereAJ,HolstI,HansellP(2000)StarchgrainsrevealearlyrootcrophorticultureinthePanamaniantropicalforest.Nature407(6806):894–897.OpenUrlCrossRefPubMed↵HenryAG,BrooksAS,PipernoDR(2011)MicrofossilsincalculusdemonstrateconsumptionofplantsandcookedfoodsinNeanderthaldiets(ShanidarIII,Iraq;SpyIandII,Belgium).ProcNatlAcadSciUSA108(2):486–491.OpenUrlAbstract/FREEFullText↵PipernoD(2006)Phytoliths:AComprehensiveGuideforArchaeologistsandPaleoecologists(AltaMira,Lanham,MD).↵ZhaoZ,PearsallD,BentferRJr,PipernoD(1998)Distinguishingrice(Oryzasativa,Poaceae)fromOryzaspeciesthroughphytolithanalysis,IIfinalisedmethod.EconBot52(2):134–145.OpenUrlCrossRef↵PipernoD,PearsallD(1993)Phytolithsinthereproductivestructuresofmaizeandteosinte:Implicationsforthestudyofmaizeevolution.JArchaeolSci20(3):337–362.OpenUrlCrossRef↵PipernoD(2009)Identifyingcropplantswithphytoliths(andstarchgrains)inCentralandSouthAmerica:Areviewandanupdateoftheevidence.QuatInt193(1-2):146–159.OpenUrlCrossRef↵KistlerL,HaneyJ,NewsomL(2012)ExperimentalinvestigationofpathogenicstressonphytolithformationinCucurbitapepovar.taxana(wildgourd).VegHistArchaeobot22(3):165–170.OpenUrl↵FullerD,etal.(2010)Consilienceofgeneticsandarchaeobotanyintheentangledhistoryofrice.ArchaeolAnthropSci2(2):115–131.OpenUrlCrossRef↵TsartsidouG,etal.(2007)Thephytolitharchaeologicalrecord:StrengthsandweaknessesevaluatedbasedonaquantitativemodernreferencecollectionfromGreece.JArchaeolSci34(8):1262–1275.OpenUrlCrossRef↵CrowtherA(2012)Thedifferentialsurvivalofnativestarchduringcookingandimplicationsforarchaeologicalanalysis:Areview.ArchaeolAnthropolSci4(3):221–235.OpenUrlCrossRef↵ShilltoL(2013)Grainsoftruthortransparentblindfold?Areviewofcurrentdebatesinphytolithanalysis.VegHistArchaeobot22(1):71–82.OpenUrlCrossRef↵SantosG,etal.(2010)Thephytolithc14Cpuzzle:Ataleofbackgrounddeterminationsandaccuracytests.Radiocarbon52(1):113–118.OpenUrl↵FullerD,HarveryE,QinL(2007)Presumeddomestication?EvidenceforwildricecultivationanddomesticationinthefifthmillenniumBCoftheLowerYangtzeregion.Antiquity81(312):316–331.OpenUrlCrossRef↵KruskaD(1988)Mammaliandomesticationanditseffectonbrainstructureandbehavior.IntelligenceandEvolutionaryBiology,edsJerisonH,JerisonI(Springer,NewYork),pp211–250.↵TurnbullP,ReedC(1974)ThefaunafromtheterminalPleistoceneofPalegawraCave.FieldianaAnthropol63:81–146.OpenUrl↵FlanneryK(1983)EarlypigdomesticationintheFertileCrescent:Aretrospectivelook.TheHillyFlanksandBeyond:EssaysonthePrehistoryofSouthwestAsia,edsYoungT,SmithP,MortensenP(UnivofChicago,Chicago),pp163–188.↵ZederM(2006)Acriticalassessmentofmarkersofinitialdomesticationingoats(Caprahircus).DocumentingDomestication:NewGeneticandArchaeologicalParadigms,edsZederM,EmshwillerE,SmithB,BradleyD(UnivofCaliforniaPress,Berkeley,CA),pp181–206.↵UerpmannH-P(1978)MetricalanalysisoffaunalremainsfromtheMiddleEast.ApproachestoFaunalAnalysisintheMiddleEast,edsMeadowR,ZederM(PeabodyMuseum,Cambridge,MA),pp41–45.↵ZederM(2001)Ametricalanalysisofacollectionofmoderngoats(CaprahircusaegargusandCaprahircushircus)fromIranandIraq:Implicationsforthestudyofcaprinedomestication.JArchaeolSci28(1):61–77.OpenUrlCrossRef↵Krause-KyoraB,etal.(2013)UseofdomesticatedpigsbyMesolithichunter-gatherersinnorthwesternEurope.NatCommun4(2348):2348.OpenUrlPubMed↵EvinA,etal.(2013)Thelongandwindingroad:Identifyingpigdomesticationthroughmolarsizeandshape.JArchaeolSci40(1):735–743.OpenUrlCrossRef↵EvinA,etal.(2015)Unravellingthecomplexityofdomestication:AcasestudyusingmorphometricsandancientDNAanalysesofarchaeologicalpigsfromRomania.PhilosTransRSocLondBBiolSci370(1660):20130616.OpenUrlAbstract/FREEFullText↵Rowley-ConwyP,ZederM(2014)Wildboarordomesticpigs?ResponsetoEvinetal.responsetoresponse.WorldArchaeol46(5):835–840.OpenUrlCrossRef↵PinhasiR,StockJ,eds(2011)HumanBioarchaeologyoftheTransitiontoAgriculture(Wiley-Blackwell,Chichester,UK).↵DobneyK,ErvynckA(2000)Interpretingdevelopmentalstressinarchaeologicalpigs:Thechronologyoflinearenamelhypoplasia.JArchaeolSci27(7):597–607.OpenUrlCrossRef↵WheelerJ(1985)Evolutionandoriginofthedomesticatedcamelids.AlpacaRegistryJournal3:1–16.OpenUrl↵MakarewiczC,TurossN(2012)Findingfodderandtrackingtranshumance:IsotopicdetectionofgoatdomesticationprocessesintheNearEast.CurrAnthropol53(4):495–505.OpenUrlCrossRef↵RosselS,etal.(2008)Domesticationofthedonkey:Timing,processes,andindicators.ProcNatlAcadSciUSA105(10):3715–3720.OpenUrlAbstract/FREEFullText↵WillcoxG,ForniteS,HerveuxL(2008)EarlyHolocenecultivationbeforedomesticationinnorthernSyria.VegHistArchaeobot17(3):313–325.OpenUrlCrossRef↵RosenA,WeinerS(1994)Identifyingancientirrigation:Anewmethodusingopalinephytolithsfromemmerwheat.JArchaeolSci21(2):125–132.OpenUrlCrossRef↵StyringAK,FraserRA,BogaardA,EvershedRP(2014)Cerealgrain,rachisandpulseseedaminoacidδ15Nvaluesasindicatorsofplantnitrogenmetabolism.Phytochemistry97:20–29.OpenUrlCrossRefPubMed↵SmithBD(2011)Generalpatternsofnicheconstructionandthemanagementof‘wild’plantandanimalresourcesbysmall-scalepre-industrialsocieties.PhilosTransRSocLondBBiolSci366(1566):836–848.OpenUrlAbstract/FREEFullText↵SmithB(2015)Documentinghumannicheconstructioninthearchaeologicalrecord.MethodandTheoryinPaleoethnobotany,edsMarstonJ,d’AlpoimGuedesJ,WarinnerC(UnivPressofColorado,Boulder,CO),pp355–370.↵Bar-OzG,NadelD(2013)Worldwidelarge-scaletrappingandhuntingofungulatesinpastsocieties.QuatInt297:1–7.OpenUrlCrossRef↵OlsenS(2006)EarlyHorseDomesticationontheEurasianSteppe.DocumentingDomestication:NewGeneticandArchaeologicalParadigms,edsZederM,EmshwillerE,SmithB,BradleyD(UnivofCaliforniaPress,Berkeley,CA),pp245–269.↵StinerMC,etal.(2014)Aforager-herdertrade-off,frombroad-spectrumhuntingtosheepmanagementatAşıklıHöyük,Turkey.ProcNatlAcadSciUSA111(23):8404–8409.OpenUrlAbstract/FREEFullText↵SmithB(2011)Aculturalnicheconstructiontheoryofinitialdomestication.BioTheory6(3):260–271.OpenUrlCrossRef↵ZederM(2012)Religionandtherevolution:TheLegacyofJacquesCauvin.Paléorient37(1):39–60.OpenUrl↵SmithB(2015)Acomparisonofnicheconstructiontheoryanddietbreadthmodelsasexplanatoryframeworksfortheinitialdomesticationofplantsandanimals.JArchaeolResdoi:10.1007/s10814-015-9081-4.OpenUrlCrossRef↵EvinA,etal.(2014)Exploringthecomplexityofdomestication:AresponsetoRowley-ConwyandZeder.WorldArchaeol46(5):825–834.OpenUrlCrossRef↵Rowley-ConwyP,ZederM(2014)MesolithicdomesticpigsatRosenhof–orwildboar?Acriticalre-appraisalofancientDNAandgeometricmorphometrics.WorldArchaeol46(5):813–824.OpenUrlCrossRef↵ZederM,SmithB(2009)Aconversationonagriculture:Talkingpasteachotherinacrowdedroom.CurrAnthropol50:681–691.OpenUrlCrossRef↵KennettD(2006)inBehavioralEcologyandtheTransitiontoAgriculture,edWinterhalderB(UnivofCaliforniaPress,Berkeley,CA).↵StinerMC(2001)Thirtyyearsonthe“broadspectrumrevolution”andpaleolithicdemography.ProcNatlAcadSciUSA98(13):6993–6996.OpenUrlFREEFullText↵GremillionK(2004)SeedprocessingandtheoriginsoffoodproductioninEasternNorthAmerica.AmAntiq69(2):215–233.OpenUrlCrossRef↵PipernoD(2006)TheoriginsofplantcultivationanddomesticationintheNeotropics:abehavioralecologicalapproach.BehavioralEcologyandtheTransitiontoAgriculture,edsKennettD,WinterhalderB(UnivofCaliforniaPress,Berkeley,CA),pp137–166.↵SmithBD(2007)Behavior.Theultimateecosystemengineers.Science315(5820):1797–1798.OpenUrlAbstract/FREEFullText↵CrawfordG(2011)AdvancesinunderstandingearlyagricultureinJapan.CurrAnthropol52(S4):S331–S345.OpenUrlCrossRef↵ZederM(2012)Thebroadspectrumrevolutionat40:Resourcediversity,intensification,andanalternativetooptimalforagingexplanations.JAnthropolArchaeol31(3):241–264.OpenUrlCrossRef↵LalandK,O’BrienM(2010)Nicheconstructiontheoryandarchaeology.JArchaeolMethodTheory17(4):303–322.OpenUrlCrossRef↵Odling-SmeeF,LalandK,FeldmanM(2003)NicheConstruction.MonographsinPopulationBiology(PrincetonUnivPress,Princeton),Vol37.↵BaronskyA,LindseyE(2010)TimingofQuaternarymegafaunalextinctioninSouthAmericainrelationtohumanarrivalandclimatechange.QuatInt217:10–29.OpenUrlCrossRef↵GneccoC,AceitunoF(2006)EarlyhumanizedlandscapesinNorthernSouthAmerica.PaleoindianArchaeology:AHemisphericPerspective,edsMorrowJ,GneccoC(UnivPressofFlorida,Gainesville,FL),pp86–104.↵StinerMC,MunroND,SurovellTA,TchernovE,Bar-YosefO(1999)Paleolithicpopulationgrowthpulsesevidencedbysmallanimalexploitation.Science283(5399):190–194.OpenUrlAbstract/FREEFullText↵StarkovichB,StinerM(2009)HallanÇemiTepesi:HighrankedgameexploitationalongsideintensiveseedprocessingattheEpipaleolithicNeolithictransitioninsoutheasternTurkey.Anthropozoologica44(1):41–61.OpenUrlCrossRef↵PipernoD,PearsallD(1998)TheOriginsofAgricultureintheLowlandNeotropics(Academic,SanDiego).↵YeshurunR,Bar-OzG,Weinstein-EvronM(2009)TheroleoffoxesintheNatufianeconomy:AviewfromMountCarmel,Israel.BeforeFarming2009/1,Article3:1–15.↵AsoutiE,KabuckuC(2014)Holocenesemi-aridoakwoodlandsintheIrano-AnatolianregionofSoutheastAsia:Naturaloranthropogenic?QuatSciRev90:158–182.OpenUrlCrossRef↵SmithB,ZederM(2013)TheonsetoftheAnthropocene.Anthropocene4:8–14.OpenUrlCrossRef PreviousNext Backtotop ArticleAlerts UserName* Password* Submit EmailArticle ThankyouforyourinterestinspreadingthewordonPNAS.NOTE:Weonlyrequestyouremailaddresssothatthepersonyouarerecommendingthepagetoknowsthatyouwantedthemtoseeit,andthatitisnotjunkmail.Wedonotcaptureanyemailaddress. YourEmail* YourName* SendTo* Entermultipleaddressesonseparatelinesorseparatethemwithcommas. Youaregoingtoemailthefollowing Corequestionsindomesticationresearch MessageSubject (YourName)hassentyouamessagefromPNAS MessageBody (YourName)thoughtyouwouldliketoseethePNASwebsite. YourPersonalMessage CAPTCHAThisquestionisfortestingwhetherornotyouareahumanvisitorandtopreventautomatedspamsubmissions. SendMessage CitationTools Corequestionsindomesticationresearch MelindaA.Zeder ProceedingsoftheNationalAcademyofSciencesMar2015,112(11)3191-3198;DOI:10.1073/pnas.1501711112 CitationManagerFormats BibTeX Bookends EasyBib EndNote(tagged) EndNote8(xml) Medlars Mendeley Papers RefWorksTagged RefManager RIS Zotero RequestPermissions Share Corequestionsindomesticationresearch MelindaA.Zeder ProceedingsoftheNationalAcademyofSciencesMar2015,112(11)3191-3198;DOI:10.1073/pnas.1501711112 ShareThisArticle: Copy TweetWidget FacebookLike Mendeley ArticleClassifications SocialSciencesAnthropologyBiologicalSciencesEvolution Seerelatedcontent: ProfileofMelindaA.Zeder -Apr06,2015 Seerelatedcontent: Humanbehavioralecologyneedsarethink -Jun01,2015 ThisarticlehasaLetter.Pleasesee:Optimalforagingtheoryandniche-constructiontheorydonotstandinopposition-June01,2015 TableofContents Submit SignupforthePNASHighlightsnewslettertogetin-depthstoriesofsciencesenttoyourinboxtwiceamonth: SignupforArticleAlerts Signup Jumptosection ArticleAbstractDefiningDomesticationandDistinguishingDomesticationfromManagementandAgricultureImpactsandMarkersCausalFactorsRelevanceAcknowledgmentsFootnotesReferencesFigures&SIInfo&MetricsPDF YouMayAlsobeInterestedin Combconstructioninhoneybees Honeybeesconstructperfectlyhexagonalcombsandsurmountarchitecturalchallengesbyalteringtheirbuildingbehavior. Imagecredit:MichaelL.Smith. Volatilechemicalproductsandozoneformation VolatilechemicalproductsfoundinpersonalcareandcleaningproductsgenerateozoneandarewidespreadincitiesintheUnitedStatesandEurope. Imagecredit:iStock/michalPuchala. PigmentcompositioninNeanderthalpaintings NeanderthalsdevelopedaformofcaveartbeforethearrivalofanatomicallymodernhumansinEurope. Imagecredit:PedroCantalejo-Duarte. InnerWorkings:Astronomersuncovernewwaytomeasurethespeedofstars Newobservationsnowallowtheseeminglyimpossible:measuringthespeedsofsomestarsalongthelineofsightwithoutascertainingtheirDopplershifts. Imagecredit:NASA,H.E.Bond,andE.Nelan(SpaceTelescopeScienceInstitute,Baltimore,MD);M.BarstowandM.Burleigh(UniversityofLeicester,UK);andJ.B.Holberg(UniversityofArizona,Tucson,AZ). JournalClub:Microbesshapehostevolution,increaselong-termfitness Evolutionarymodelssuggestthatpassingthemicrobiomeperfectlyfromparenttooffspringisbeneficialinconstantenvironments. Imagecredit:Shutterstock/FrancesvanderMerwe. SimilarArticles