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万物简史英文版_比尔·布莱森-第87章

小说: 万物简史英文版_比尔·布莱森 字数: 每页3500字

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 happilyto use neandertal tools鈥攈ardly convincing evidence of overwhelming superiority。 no lesscuriously; acheulean tools are found in the middle east well over a million years ago; but scarcely exist in europe until just 300;000 years ago。 again; why people who had thetechnology didn鈥檛 take the tools with them is a mystery。

for a long time; it was believed that the cro…magnons; as modern humans in europebecame known; drove the neandertals before them as they advanced across the continent;eventually forcing them to its western margins; where essentially they had no choice but tofall in the sea or go extinct。 in fact; it is now known that cro…magnons were in the far west ofeurope at about the same time they were also ing in from the east。 鈥渆urope was a prettyempty place in those days;鈥潯attersall says。 鈥渢hey may not have encountered each other allthat often; even with all their ings and goings。鈥潯ne curiosity of the cro…magnons鈥櫋rrivalis that it came at a time known to paleoclimatology as the boutellier interval; when europewas plunging from a period of relative mildness into yet another long spell of punishing cold。

whatever it was that drew them to europe; it wasn鈥檛 the glorious weather。

in any case; the idea that neandertals crumpled in the face of petition from newlyarrived cro…magnons strains against the evidence at least a little。 neandertals were nothing ifnot tough。 for tens of thousands of years they lived through conditions that no modern humanoutside a few polar scientists and explorers has experienced。 during the worst of the ice ages;blizzards with hurricane…force winds were mon。 temperatures routinely fell to 50 degreesbelow zero fahrenheit。 polar bears padded across the snowy vales of southern england。

neandertals naturally retreated from the worst of it; but even so they will have experiencedweather that was at least as bad as a modern siberian winter。 they suffered; to be sure鈥攁neandertal who lived much past thirty was lucky indeed鈥攂ut as a species they weremagnificently resilient and practically indestructible。 they survived for at least a hundredthousand years; and perhaps twice that; over an area stretching from gibraltar to uzbekistan;which is a pretty successful run for any species of being。

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鈥攖hequintessential 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鈥檚 posture had been misdescribed。 infact; it was the latter。 neandertal vertebrae were not simian at all。 it changed utterly how weviewed neandertals鈥攂ut 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鈥檚 slender and more cerebrally nimble newers; homosapiens。 here is a typical ment from a recent book: 鈥渕odern humans neutralized thisadvantage 'the neandertal鈥檚 considerably heartier physique' with better clothing; better firesand better shelter; meanwhile the neandertals were stuck with an oversize body that requiredmore food to sustain。鈥潯n 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鈥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鈥攖hat 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。

鈥渆xcept that for me there are no homo erectus;鈥潯ays thorne。 鈥渋 think it鈥檚 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。鈥

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鈥攊n 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 鈥渂ushmen鈥

(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 鈥渞hodesian 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。鈥潯n other words black africans were recently descended fromcreatures that were only 鈥渃lose鈥潯o 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。 鈥渢here鈥檚 no reason tosuppose that people only went in one direction;鈥潯e says。 鈥減eople were moving all over theplace; and where they met they almost certainly shared genetic material throughinterbreeding。 new arrivals didn鈥檛 replace the indigenous populations; they joined them。 theybecame them。鈥潯e likens the situation to when explorers like cook or magellan encounteredremote peoples for the first time。 鈥渢hey weren鈥檛 meetings of different species; but of the samespecies with some physical differences。鈥

what you actually see in the fossil record; thorne insists; is a smooth; continuoustransition。 鈥渢here鈥檚 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。鈥

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 鈥渟hoveling鈥潯attern; 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鈥檛more blended。 as one critic put it: 鈥渋f you look at a mule; you don鈥檛 have the front endlooking like a donkey and the back end looking like a horse。鈥

ian tattersall declared it to be nothing more than 鈥渁 chunky modern child。鈥潯e accepts thatthere may well have been some 鈥渉anky…panky鈥潯etween neandertals and moderns; butdoesn鈥檛 believe it could have resulted in reproductively successful offspring。

1鈥渋 don鈥檛 knowof any two organisms from any realm of biology that are that different and still in the samespecies;鈥潯e 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鈥檛 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 鈥渁ll present…day humans aredescended from that population。鈥潯t 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鈥攁lmost too extraordinary to credit really鈥攚as that the 鈥渁fricans鈥潯sed 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

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