教材职称英新增文章.doc

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1、第四十八篇ResearchersDiscoverWhyHumansBeganWalkingUpright　　Mostofuswalkandcarryitemsinourhandseveryday.Theseareseeminglysimpleactivitiesthatthemajorityofusdon’tquestion.Butaninternationalteamofresearchers,includingDr.RichmondfromGW’sColumbianCollegeofArtsandScienc

2、es，havediscoveredthathumanwalkingupright,mayhaveoriginatedmillionsofyearsagoasanadaptationtocarryingscarce,high-qualityresources.TheteamofresearchersfromtheU.S.,England,JapanandPortugalinvestigatedthebehaviorofmodern-daychimpanzeesastheycompetedforfoodresourc

3、es，inanefforttounderstandwhatecologicalsettingswouldleadalargeape—onethatresemblesthe6million-yearoldancestorwesharedincommonwithlivingchimpanzees—towalkontwolegs.　　“Thesechimpanzeesprovideamodeloftheecologicalconditionsunderwhichourearliestancestorsmighthave

4、begunwalkingontwolegs,"，saidDr.Richmond.　　Theresearchfindingssuggestthatchimpanzeesswitchtomovingontwolimbsinsteadoffourinsituationswheretheyneedtomonopolizearesource.Standingontwolegsallowsthemtocarrymuchmoreatonetimebecauseitfreesuptheirhands.Overtime，inten

5、seburstsofbipedalactivitymayhaveledtoanatomicalchangesthatinturnbecamethesubjectofnaturalselectionwherecompetitionforfoodorotherresourceswasstrong.　　TwostudieswereconductedbytheteaminGuinea.ThefirststudywasconductedbytheteaminKyotoUniversity’s“outdoorlaborato

6、ry”inanaturalclearinginBossouForest.Researchersallowedthewildchimpanzeesaccesstodifferentcombinationsoftwodifferenttypesofnut—theoilpalmnut，whichisnaturallywidelyavailable,andthecoulanut,whichisnot.Thechimpanzees’behaviorwasmonitoredinthreesituations:(a)wheno

7、nlyoilpalmnutswereavailable,(b)whenasmallnumberofcoulanutswereavailable，and(c)whencoulanutswerethemajorityavailableresource.　　Whentherarecoulanutswereavailableonlyinsmallnumbers,thechimpanzeestransportedmoreatonetime.Similarly,whencoulanutswerethemajorityreso

8、urce,thechimpanzeesignoredtheoilpalmnutsaltogether.Thechimpanzeesregardedthecoulanutsasamorehighly-prizedresourceandcompetedforthemmoreintensely.　　Insuchhigh-competitionsettings，thefreque