A Short History of Nearly Everything-第101章

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quite　who　they　were　and　what　they　were　like　remain　matters　of　disagreement　anduncertainty。　right　up　until　the　middle　of　the　twentieth　century　the　accepted　anthropologicalview　of　the　neandertal　was　that　he　was　dim；　stooped；　shuffling；　and　simian—thequintessential　caveman。　it　was　only　a　painful　accident　that　prodded　scientists　to　reconsiderthis　view。　in　1947；　while　doing　fieldwork　in　the　sahara；　a　franco…algerian　paleontologistnamed　camille　arambourg　took　refuge　from　the　midday　sun　under　the　wing　of　his　lightairplane。　as　he　sat　there；　a　tire　burst　from　the　heat；　and　the　plane　tipped　suddenly；　striking　hima　painful　blow　on　the　upper　body。　later　in　paris　he　went　for　an　x…ray　of　his　neck；　and　noticedthat　his　own　vertebrae　were　aligned　exactly　like　those　of　the　stooped　and　hulking　neandertal。

either　he　was　physiologically　primitive　or　neandertal’s　posture　had　been　misdescribed。　infact；　it　was　the　latter。　neandertal　vertebrae　were　not　simian　at　all。　it　changed　utterly　how　weviewed　neandertals—but　only　some　of　the　time；　it　appears。

it　is　still　monly　held　that　neandertals　lacked　the　intelligence　or　fiber　to　pete　onequal　terms　with　the　continent’s　slender　and　more　cerebrally　nimble　newers；　homosapiens。　here　is　a　typical　ment　from　a　recent　book：　“modern　humans　neutralized　thisadvantage　＇the　neandertal’s　considerably　heartier　physique＇　with　better　clothing；　better　firesand　better　shelter；　meanwhile　the　neandertals　were　stuck　with　an　oversize　body　that　requiredmore　food　to　sustain。”　in　other　words；　the　very　factors　that　had　allowed　them　to　survivesuccessfully　for　a　hundred　thousand　years　suddenly　became　an　insuperable　handicap。

above　all　the　issue　that　is　almost　never　addressed　is　that　neandertals　had　brains　that　weresignificantly　larger　than　those　of　modern　people—1。8　liters　for　neandertals　versus　1。4　formodern　people；　according　to　one　calculation。　this　is　more　than　the　difference　betweenmodern　homo　sapiens　and　late　homo　erectus　；　a　species　we　are　happy　to　regard　as　barelyhuman。　the　argument　put　forward　is　that　although　our　brains　were　smaller；　they　weresomehow　more　efficient。　i　believe　i　speak　the　truth　when　i　observe　that　nowhere　else　inhuman　evolution　is　such　an　argument　made。

so　why　then；　you　may　well　ask；　if　the　neandertals　were　so　stout　and　adaptable　andcerebrally　well　endowed；　are　they　no　longer　with　us？　one　possible　（but　much　disputed）answer　is　that　perhaps　they　are。　alan　thorne　is　one　of　the　leading　proponents　of　an　alternativetheory；　known　as　the　multiregional　hypothesis；　which　holds　that　human　evolution　has　beencontinuous—that　just　as　australopithecines　evolved　into　homo　habilis　and　homoheidelbergensis　became　over　time　homo　neanderthalensis；　so　modernhomo　sapiens　simplyemerged　from　more　ancient　homo　forms。homo　erectus　is；　on　this　view；　not　a　separate　speciesbut　just　a　transitional　phase。　thus　modern　chinese　are　descended　from　ancient　homo　erectusforebears　in　china；　modern　europeans　from　ancient　european　homo　erectus；　and　so　on。

“except　that　for　me　there　are　no　homo　erectus；”　says　thorne。　“i　think　it’s　a　term　which　hasoutlived　its　usefulness。　for　me；　homo　erectus　is　simply　an　earlier　part　of　us。　i　believe　onlyone　species　of　humans　has　ever　left　africa；　and　that　species　ishomo　sapiens。”

opponents　of　the　multiregional　theory　reject　it；　in　the　first　instance；　on　the　grounds　that　itrequires　an　improbable　amount　of　parallel　evolution　by　hominids　throughout　the　old　world—in　africa；　china；　europe；　the　most　distant　islands　of　indonesia；　wherever　they　appeared。　somealso　believe　that　multiregionalism　encourages　a　racist　view　that　anthropology　took　a　very　longtime　to　rid　itself　of。　in　the　early　1960s；　a　famous　anthropologist　named　carleton　coon　of　theuniversity　of　pennsylvania　suggested　that　some　modern　races　have　different　sources　oforigin；　implying　that　some　of　us　e　from　more　superior　stock　than　others。　this　hearkenedback　unfortably　to　earlier　beliefs　that　some　modern　races　such　as　the　african　“bushmen”

（properly　the　kalahari　san）　and　australian　aborigines　were　more　primitive　than　others。

whatever　coon　may　personally　have　felt；　the　implication　for　many　people　was　that　someraces　are　inherently　more　advanced；　and　that　some　humans　could　essentially　constitutedifferent　species。　the　view；　so　instinctively　offensive　now；　was　widely　popularized　in　manyrespectable　places　until　fairly　recent　times。　i　have　before　me　a　popular　book　published　bytime…life　publications　in　1961　called　the　epic　of　man　based　on　a　series　of　articles　in　lifemagazine。　in　it　you　can　find　such　ments　as　“rhodesian　man　。　。　。　lived　as　recently　as25；000　years　ago　and　may　have　been　an　ancestor　of　the　african　negroes。　his　brain　size　wasclose　to　that　of　homo　sapiens。”　in　other　words　black　africans　were　recently　descended　fromcreatures　that　were　only　“close”　to　homo　sapiens。

thorne　emphatically　（and　i　believe　sincerely）　dismisses　the　idea　that　his　theory　is　in　anymeasure　racist　and　accounts　for　the　uniformity　of　human　evolution　by　suggesting　that　therewas　a　lot　of　movement　back　and　forth　between　cultures　and　regions。　“there’s　no　reason　tosuppose　that　people　only　went　in　one　direction；”　he　says。　“people　were　moving　all　over　theplace；　and　where　they　met　they　almost　certainly　shared　genetic　material　throughinterbreeding。　new　arrivals　didn’t　replace　the　indigenous　populations；　they　joined　them。　theybecame　them。”　he　likens　the　situation　to　when　explorers　like　cook　or　magellan　encounteredremote　peoples　for　the　first　time。　“they　weren’t　meetings　of　different　species；　but　of　the　samespecies　with　some　physical　differences。”

what　you　actually　see　in　the　fossil　record；　thorne　insists；　is　a　smooth；　continuoustransition。　“there’s　a　famous　skull　from　petralona　in　greece；　dating　from　about　300；000　yearsago；　that　has　been　a　matter　of　contention　among　traditionalists　because　it　seems　in　some　wayshomo　erectus　but　in　other　ways　homo　sapiens。　well；　what　we　say　is　that　this　is　just　what　youwould　expect　to　find　in　species　that　were　evolving　rather　than　being　displaced。”

one　thing　that　would　help　to　resolve　matters　would　be　evidence　of　interbreeding；　but　that　isnot　at　all　easy　to　prove；　or　disprove；　from　fossils。　in　1999；　archeologists　in　portugal　found　theskeleton　of　a　child　about　four　years　old　that　died　24；500　years　ago。　the　skeleton　was　modernoverall；　but　with　certain　archaic；　possibly　neandertal；　characteristics：　unusually　sturdy　legbones；　teeth　bearing　a　distinctive　“shoveling”　pattern；　and　（though　not　everyone　agrees　on　it）an　indentation　at　the　back　of　the　skull　called　a　suprainiac　fossa；　a　feature　exclusive　toneandertals。　erik　trinkaus　of　washington　university　in　st。　louis；　the　leading　authority　onneandertals；　announced　the　child　to　be　a　hybrid：　proof　that　modern　humans　and　neandertalsinterbred。　others；　however；　were　troubled　that　the　neandertal　and　modern　features　weren’tmore　blended。　as　one　critic　put　it：　“if　you　look　at　a　mule；　you　don’t　have　the　front　endlooking　like　a　donkey　and　the　back　end　looking　like　a　horse。”

ian　tattersall　declared　it　to　be　nothing　more　than　“a　chunky　modern　child。”　he　accepts　thatthere　may　well　have　been　some　“hanky…panky”　between　neandertals　and　moderns；　butdoesn’t　believe　it　could　have　resulted　in　reproductively　successful　offspring。

1“i　don’t　knowof　any　two　organisms　from　any　realm　of　biology　that　are　that　different　and　still　in　the　samespecies；”　he　says。

with　the　fossil　record　so　unhelpful；　scientists　have　turned　increasingly　to　genetic　studies；in　particular　the　part　known　as　mitochondrial　dna。　mitochondrial　dna　was　only　discoveredin　1964；　but　by　the　1980s　some　ingenious　souls　at　the　university　of　california　at　berkeley　hadrealized　that　it　has　two　features　that　lend　it　a　particular　convenience　as　a　kind　of　molecularclock：　it　is　passed　on　only　through　the　female　line；　so　it　doesn’t　bee　scrambled　withpaternal　dna　with　each　new　generation；　and　it　mutates　about　twenty　times　faster　than　normalnuclear　dna；　making　it　easier　to　detect　and　follow　genetic　patterns　over　time。　by　tracking　therates　of　mutation　they　could　work　out　the　genetic　history　and　relationships　of　whole　groups　ofpeople。

in　1987；　the　berkeley　team；　led　by　the　late　allan　wilson；　did　an　analysis　of　mitochondrialdna　from　147　individuals　and　declared　that　the　rise　of　anatomically　modern　humansoccurred　in　africa　within　the　last　140；000　years　and　that　“all　present…day　humans　aredescended　from　that　population。”　it　was　a　serious　blow　to　the　multiregionalists。　but　thenpeople　began　to　look　a　little　more　closely　at　the　data。　one　of　the　most　extraordinary　points—almost　too　extraordinary　to　credit　really—was　that　the　“africans”　used　in　the　study　wereactually　african…americans；　whose　genes　had　obviously　been　subjected　to　considerablemediation　in　the　past　few　hundred　years。　doubts　also　soon　emerged　about　the　assumed　ratesof　mutations。

by　1992；　the　study　was　largely　discredited。　but　the　techniques　of　genetic　analysiscontinued　to　be　refined；　and　in　1997　scientists　from　the　university　of　munich　managed　toextract　and　analyze　some　dna　from　the　arm　bone　of　the　original　neandertal　man；　and　thistime　the　evidence　stood　up。　the　munich　study　found　that　the　neandertal　dna　was　unlike　anydna　found　on　earth　now；　strongly　indicating　that　there　w