题目内容：
A．Whenyourunyourhandsthroughyourlover'shair,you'reprobablynotthinkingaboutyourplaceinthesocialhierarchy(等级制度).Giveyourteam-mateorcolleagueapatonthebackafterfailure,andthechancesareyou'renotconsciouslyseekingtochangethemixofsignallingchemicalsintheirbrain.Itmaynotseemlikeit,butthesesociallyimportantritualsandotherslikethemhasemergedbeforethetimeourspeciesfirstwalkedtheAfricanlargegrassyplain.
B．Humanbehavioursthatinvolvephysicalsocialcontacthavealotmoreincommonwithsocialgrooming(整饰，梳理毛发)activitieswetypicallyassociatewithotherspeciesthanwemightinitiallythink.Whenrhesusmonkeys(恒河猴)orchimpanzees(黑猩猩)pickthroughtheirfriends'fur,they'renotjusthelpingthemremovedirtfromhard-to-reachspots.Thereisundoubtedlyahygienic(卫生的)benefit,butthisbehaviour,whichanimalbehaviourresearcherscall"allogrooming",hasfargreatersignificance.
Allogroomingisthecurrencyofwhatprimatologist(灵长类动物学家)FransdeWaalcallsthe"marketplaceofservices"inchimpanzeelife:itdefinesthesocialhierarchy,whichinturndictatesaccesstofood,sex,andsocialsupport.Forexample,onechimpanzeeismorelikelytosharefoodwithanotherthathaspreviouslygroomedit.Groomingalsoservestoeasetensionsinachimptroopfollowinganaggressivesituation.Oneofthemostcomplexformsofreconciliationamongchimpanzeesoccurswhentworivalmalesreachapointofstalemate(僵局),neitherbackingdownnorincreasingtheaggressiveinteraction.Sometimes,afemalebreaksthestalemateandeasesthetensionbygroomingfirstonemale,andthentheother,untilthetwobecomerelaxedenoughtoendwhatamountedtoanangrystatingcontest.
C．Accordingtoanthropologist(人类学家)RobinDunbar,thisworksbecausegroomingstimulatesthereleaseofendorphins(内啡肽)whichcanbringaboutfeelingsofrelaxationbyloweringtheheartrate,reducingobviousnervousbehaviourslikescratching,andevenbringingonsleep.Femalechimpsthatusegroomingasapeacekeepingstrategymayalsoexperiencetheirownrushofendorphinsandenjoymanyofthesamebenefits.
D．Humans,lackingthefurofourevolutionarycousins,hadtofindareplacementforallogrooming.Likegrooming,gossipestablishesandmaintainsourplaceinthesocialhierarchy.Alsolikegrooming,thesocialinformationthatmakesupgossipisitselfaformofcurrencyinhumanculture.Or,atleast,that'sthetheoryputforwardbyDunbar.Heargued,inhisbookGrooming,GossipandtheEvolutionofLanguage,thatthefacultyoflanguageallowedourspeciestosubstitutegossipforgrooming.
E．Butgrooming,andrelatedformsofsocialphysicalcontact,hasn'tgoneawayentirely.Wordsdon'talwaysmakeadequatetoolsforcommunicatingourfeelings.Farmorecanbesaidbyasincerehugorpatontheshoulderafterafriendsuffersthelossofarelativethanthroughwords.Inthesameway,one'sloveanddesireforapartnercanbeconveyedwithatenderstrokefarmoreeffectivelythaneventhewords"Iwantyou"evercould.Indeed,Dunbarwrites,"thephysicalstimulationoftouchtellsusmoreabouttheinnerfeelingsofthe'groomer',andinamoredirectway"thanwordsareable.Andthoseformsoftouchstimulatewithinusthesameendorphinreleasethatchimpanzeesenjoyduringsocialgrooming.
F．Somescientistshaveevengoneasfarascallingtheskina"socialorgan".
Thismakesgoodintuitivesense:webothdesirefortouchandhateitwhenitisunwanted,uninvited,orinappropriate.Evensimple,brieftouchesonahandorarmcanhavetremendouseffects.IndiaMorrisonandcolleaguesatGoteborgUniversity,inSweden,havepresentedalaundrylistofsuchfindings.Hand-on-handtouchesbylibrariansandsalespersonshave,forexample,beenfoundtoleadtomorefavourableimpressionsoflibrariesandshops.Peopleperceiveothersasmoreattractivefollowingevenasimple,non-sexualtouch,andasaresultaremorelikelytoactaltruistically(利他地)byreturningchangeleftinapayphone,givingbiggertipsinrestatlrants,orgivingawayacigarettetoastranger.
G．Andyettheseeffectsmightbethoughtofassimpletrickscomparedtothepowerthattouchhasbetweenlovers,orbetweenparentsandtheirchildren.
Inonestudy,USpsychologistsinvestigatedsocialgroominginhumansbyaskingparticipantstoindicatetheirclosestemotionalrelationshipandreportbehaviourssuchasrunningtheirfingersthroughtheperson'shair,wipingawaytheirtears,scratchingtheirbackandnon-sexualmassage.Theyfoundlevelsofrelationshipsatisfactionandtrustwerebothpositivelycorrelatedwithself-reportedgroomingfrequencyamongromanticpartners.Andonefindinghintedatacausalrelationship:peoplewhoweremoreanxiousabouttheirrelationships"groomed"theirpartnersmoreoftenthanthosewhofeltmoresecurewiththeirpartners,suggestingthatgroomingmayservetoreducerelationship-relatedanxietyandtopromotethedevelopmentofromanticbonds.Thepatternwastruebothformenandwomen.
H．Babiesalsocravetouch.Ithaslongbeenknownamonganimalbehaviourresearchersthatphysicalcontactiscriticalforpropersocialandemotionaldevelopment.WhendevelopmentalpsychologistHarryHarlowpreventinfantrhesusmonkeysfromapproachingamonkeymotherinhis1950sexperimentsattheUniversityofWisconsin-Madison,theybecamewithdrawn,depressed,andanxious.Theyrefusedfood,andenteredintowhathecalleda"stateofemotionalshock".Whenallowedaccesstoasurrogatemother(代理母亲),theinfantmonkeysoverwhelminglychoseadollcoveredbyterryclothoverawiredollthatprovidedfoodandwater.Theyoungmonkeyspreferredthecomfortofevenaninanimatemother'stouchtofood.
L．MorerecentresearchwithratsgotwhatissimilartoHarlow'searlyfindings.
Canadianresearchersfoundthatwheninfantratswerelickedandgroomedmorebytheirmothers,theygrewuptoberelativelywelladjusted.Buttheircounterpartswhowerenotgroomedoftengrewup,likeHarlow'smonkeys,tobeanxiousandfearful.Touch-deprivedratsalsohadweakenedimmunesystems.Itappearsasiftouchhelpstomaintainnotonlysocialandemotionalhealth,butalsophysicalhealth.
J．Allprimates,frommonkeytoman,relyonsocialtouch.Amongnon-humanprimates,groomingisatoolusedtogetfavours,earnsocialstanding,andincreaseaccesstoresources.Gossipmayhavereplaceddirtremovalasamechanismfordefiningandenhancingone'splaceinhumansociety,butthedesiretobetouchediscarvedsodeeplywithinourprimateheritagethatitremainedevenasweshedourfur.
RobinDunbarbelievesthatgroomingcanbringaboutfeelingsofrelaxation.
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