大象的嗅觉动物界最灵敏 ResearchershavediscoveredthatAfricanElephantshavethelargestnumberofgenesdedicatedtosmellofanymammal. 研究人员发现，非洲大象拥有数量最多的基因，这些基因有利于所有哺乳动物的嗅觉。 Giventhesizeoftheirtrunks, andhowimportantitistotheirsurvival, itisprobablyunsurprisingthatanelephantsnoseisnotonlythelongestintheanimalkingdom, butalsothemosteffective. Incomparison, humansandotherprimateshaveapoorsenseofsmell. Thefunctionsofthesegenesarenotwellknown, buttheyarelikelyimportantforthelivingenvironmentofAfricanelephants, saidauthorDrYoshihitoNiimuraoftheUniversityofTokyo. Apparently, anelephantsnoseisnotonlylongbutalsosuperior. Thesenseofsmelliscriticaltoallmammals, andtheyuseitforsniffingoutfood, avoidingpredators, findingmatesandlocatingtheiroffspring. InastudypublishedinGenomeResearch, scientistsexaminedthe 13 mammalspeciesandfoundthatAfricanElephantshavetwicethenumberofsmellgenesasdogsandfivetimesmorethanhumans. Theyhavearound 2,000 genesalonethatarededicatedtoscent. Humansincomparisonhavejustunder 400 andotherprimateslikechimpanzees, evenless. Thestudyfoundthat 20,000 genesareresponsibleforthesenseofsmellinmammals, ofwhicharoundhalfarefunctional, butthecollectionsdifferforeachspecies. Horseshavearound 1,000 smellgenes, rabbitsaround 750 andratsabout 1,200. Thelargerepertoireofelephantgenesmightbeattributedtoelephantsheavyrelianceonscentinvariouscontexts, includingforaging, socialcommunication, andreproduction, addedDrNiimura