2022年職稱英語理工類教材新增部分內(nèi)容(八)3

2022年職稱英語理工類教材新增部分內(nèi)容(八)3Ateamofscientiststhatstudiedchimpanzeestrainedtousetreadmillshasgatherednewevidencesuggestingthatourearliestapelikeancestorsstartedwalkingontwolegsbecauseitrequiredlessenergythangettingaroundonallfours.

“Whenourearliestancestorsstartedwalkingontwolegs,theytookthefirststepstowardbecominghuman,“saidleadresearcherMichaelSockolofUCDavis1.“Ourfindingshelpanswerwhy.“Sockolworkedfortwoyearstofindananimaltrainerwillingtocoaxadultchimpstowalkontwolegsandto“knucklewalk“onallfoursonthesortoftreadmillfoundinmostgyms.

Thefivechimpsalsoworefacemasksusedtohelptheresearchersmeasureoxygenconsumption.Whilethechimpsworkedout,thescientistscollectedmetabolicandotherdatathatallowedthemtocalculatewhichmethodoflocomotionusedlessenergyandwhy.Theteamgatheredthesameinformationforfouradulthumanswalkingonatreadmill.

Theresearchersfoundthathumanwalkingusedabout75percentlessenergyandburned75percentfewercaloriesthanquadrupedalandbipedal2walkinginchimpanzees.Theyalsofoundthatforsomebutnotallofthechimps,walkingontwolegswasnomorecostlythanknucklewalking.

“Wewerepreparedtofindthatallofthechimpsusedmoreenergywalkingontwolegs-butthatfindingwouldn”thavebeenasinteresting,“Sockolsaid.“Whatwefoundwasmuchmoretelling.Forthreechimps,bipedalism3wasmoreexpensive,butfortheothertwochimps,thiswasn”tthecase.Onespentaboutthesameenergywalkingontwolegsasonfour.Theotherusedlessenergywalkingupright.“Thesetwochimpshaddifferentgaitsandanatomythantheirknucklewalkingpeers.

Takentogether,thefindingsprovidesupportforthehypothesisthatanatomicaldifferencesaffectinggaitexistedamongourearliestapelikeancestors,andthatthesedifferencesprovidedthegeneticvariationwhichnaturalselectioncouldactonwhenchangesintheenvironmentgavebipedsanadvantageoverquadrupeds.

FossilandmolecularevidencesuggeststheearliestancestorsofthehumanfamilylivedinforestedareasinequatorialAfricainthelateMioceneerasome8to10millionyearsago,whenchangesinclimatemayhaveincreasedindistancebetweenfoodpatches.Thatwouldhaveforcedourearliestancestorstotravellongerdistancesonthegroundandfavoredthosewhocouldcovermoregroundusinglessenergy.

“Thisisn”tthecompleteanswer,“Sockolsaid.“Butit”sagoodpieceofapuzzlehumanshavealwayswonderedabout:Howandwhydidwebecomehuman?Andwhydowealonewalkontwolegs?“(435words)

詞匯：

chimpanzeen.黑猩猩（又作chimp）

calorien.卡（路里），小卡

bipedn二足動(dòng)物

treadmilln.踏輪；踏車；單調(diào)工作

gaitn.步態(tài)，步法

coaxv.哄，哄勸

anat