【Whydowecry?Themainreasonsayscientistsisbecausewearehuman.Asfarastheycantellnoothercreaturecriesemotionaltearsthewaywehumansdodespiteanumberofreportsofanelephantorgorillanotjustmakingsadsoundsbut】

　　Whydowecry?Themainreasonsayscientistsisbecausewearehuman.

　　Asfarastheycantellnoothercreaturecriesemotionaltearsthewaywehumansdodespiteanumberofreportsofanelephantorgorillanotjustmakingsadsoundsbutactuallyflowingtears.

　　InterestedbyonesuchreportofanIndianelephantcryingafterbeingcaughtCharlesDarwinsentaco-workertocheckitoutbuthecouldn’tconfirmit.

　　Ifemotionaltearsareindeedauniquelyhumanacttheremustbeanevolutionaryadvantagetocryingpossiblyabigonebutwhat?

　　PsychologistRobertR.ProvineattheUS’suniversityofMarylandcarriedoutsomeresearch.InapaperpublishedinthejournalEvolutionaryPsychologyhereportedthattearsmayhaveevolvedtogivemorecharmstofacialexpressionsofemotionsincludingsadness.

　　InanexperimentProvine‘steamasked80collegestudentstoratetheintensity(强度)offacialexpressionsofsadness.Halfofthepicturesshowedapersonwithtearsflowingdownhisorherfacewhiletheotherhalfwerethesamepicturesbutwiththetearsdigitallyremoved.Thesepictureswereshowntothestudentswith“distractor”picturesofpeoplewithotherfacialexpressions.

　　Thestudentsoverwhelminglyrankedthepicturesshowingtearsasrevealingmoresadnessthanthesamefaceswithouttears.

　　Thefactthatanimalsprobablydon’tcryemotionaltearsandthefactthatittakesnewbornsseveralmonthstoaddtearstotheircryingsupporttheresearchers'beliefthatemotionalcryingisarecentevolutionarydevelopment.

　　AndinapaperpublishedinEvolutionaryPsychologyinresponsetoProvine’sworkIsraelievolutionarybiologistOrenHassonatTelAvivUniversitysaidthatemotionaltearsmayalsoactasacallforhelpandforbonding.

　　Butthere’sanotherreasonwhyemotionaltearsmayhaveevolvedsaidWilliamH.FreyaUSbiochemist.Humansevolvedtheabilitytoshedtearsasameanstoreducestressandevolutionfavorsthisbecauseithassurvivalvalue.’，saysFrey.

　　Viewingtearsnotjustascommunicationsignalsbutalsoasstressrelieversmayhelpexplainwhypeopledon’tjustcrywhenthere’sanaudiencebutalsocryalonewhenthere’snobodyaroundtoreceivethecommunication.

　　32.RobertR.Provine