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eds more food and more food means increased risk。
tattersall thinks the rise of a big brain may simply have been an evolutionary accident。 hebelieves with stephen jay gould that if you replayed the tape of life鈥攅ven if you ran it backonly a relatively short way to the dawn of hominids鈥攖he chances are 鈥渜uite unlikely鈥潯hatmodern humans or anything like them would be here now。
鈥渙ne of the hardest ideas for humans to accept；鈥潯e says； 鈥渋s that we are not theculmination of anything。 there is nothing inevitable about our being here。 it is part of ourvanity as humans that we tend to think of evolution as a process that； in effect； wasprogrammed to produce us。 even anthropologists tended to think this way right up until the1970s。鈥潯ndeed； as recently as 1991； in the popular textbook the stages of evolution； c。
loring brace stuck doggedly to the linear concept； acknowledging just one evolutionary deadend； the robust australopithecines。 everything else represented a straightforwardprogression鈥攅ach species of hominid carrying the baton of development so far； then handingit on to a younger； fresher runner。 now； however； it seems certain that many of these earlyforms followed side trails that didn鈥檛 e to anything。
luckily for us； one did鈥攁 group of tool users； which seemed to arise from out of nowhereand overlapped with the shadowy and much disputed homo habilis。 this is homo erectus； thespecies discovered by eug猫ne dubois in java in 1891。 depending on which sources youconsult； it existed from about 1。8 million years ago to possibly as recently as twenty thousandor so years ago。
according to the java man authors； homo erectus is the dividing line： everything thatcame before him was apelike in character； everything that came after was humanlike。 homoerectus was the first to hunt； the first to use fire； the first to fashion plex tools； the first toleave evidence of campsites； the first to look after the weak and frail。 pared with all thathad gone before； homo erectus was extremely human in form as well as behavior； itsmembers long…limbed and lean； very strong （much stronger than modern humans）； and withthe drive and intelligence to spread successfully over huge areas。 to other hominids； homoerectus must have seemed terrifyingly powerful； fleet； and gifted。
erectus was 鈥渢he velociraptor of its day；鈥潯ccording to alan walker of penn stateuniversity and one of the world鈥檚 leading authorities。 if you were to look one in the eyes； itmight appear superficially to be human； but 鈥測ou wouldn鈥檛 connect。 you鈥檇 be prey。鈥�
according to walker； it had the body of an adult human but the brain of a baby。
although erectus had been known about for almost a century it was known only fromscattered fragments鈥攏ot enough to e even close to making one full skeleton。 so it wasn鈥檛until an extraordinary discovery in africa in the 1980s that its importance鈥攐r； at the veryleast； possible importance鈥攁s a precursor species for modern humans was fully appreciated。
the remote valley of lake turkana （formerly lake rudolf） in kenya is now one of theworld鈥檚 most productive sites for early human remains； but for a very long time no one hadthought to look there。 it was only because richard leakey was on a flight that was divertedover the valley that he realized it might be more promising than had been thought。 a teamwas dispatched to investigate； but at first found nothing。 then late one afternoon kamoya kimeu； leakey鈥檚 most renowned fossil hunter； found a small piece of hominid brow on a hillwell away from the lake。 such a site was unlikely to yield much； but they dug anyway out ofrespect for kimeu鈥檚 instincts and to their astonishment found a nearly plete homo erectusskeleton。 it was from a boy aged between about nine and twelve who had died 1。54 millionyears ago。 the skeleton had 鈥渁n entirely modern body structure；鈥潯ays tattersall； in a way thatwas without precedent。 the turkana boy was 鈥渧ery emphatically one of us。鈥�
also found at lake turkana by kimeu was knm…er 1808； a female 1。7 million years old；which gave scientists their first clue that homo erectus was more interesting and plexthan previously thought。 the woman鈥檚 bones were deformed and covered in coarse growths；the result of an agonizing condition called hypervitaminosis a； which can e only fromeating the liver of a carnivore。 this told us first of all that homo erectus was eating meat。
even more surprising was that the amount of growth showed that she had lived weeks or evenmonths with the disease。 someone had looked after her。 it was the first sign of tenderness inhominid evolution。
it was also discovered that homo erectus skulls contained （or； in the view of some； possiblycontained） a broca鈥檚 area； a region of the frontal lobe of the brain associated with speech。
chimps don鈥檛 have such a feature。 alan walker thinks the spinal canal didn鈥檛 have the sizeand plexity to enable speech； that they probably would have municated about as wellas modern chimps。 others； notably richard leakey； are convinced they could speak。
for a time； it appears； homo erectus was the only hominid species on earth。 it was hugelyadventurous and spread across the globe with what seems to have been breathtaking rapidity。
the fossil evidence； if taken literally； suggests that some members of the species reached javaat about the same time as； or even slightly before； they left africa。 this has led some hopefulscientists to suggest that perhaps modern people arose not in africa at all； but in asia鈥攚hichwould be remarkable； not to say miraculous； as no possible precursor species have ever beenfound anywhere outside africa。 the asian hominids would have had to appear； as it were；spontaneously。 and anyway an asian beginning would merely reverse the problem of theirspread； you would still have to explain how the java people then got to africa so quickly。
there are several more plausible alternative explanations for how homo erectus managedto turn up in asia so soon after its first appearance in africa。 first； a lot of plus…or…minusinggoes into the dating of early human remains。 if the actual age of the african bones is at thehigher end of the range of estimates or the javan ones at the lower end； or both； then there isplenty of time for african erects to find their way to asia。 it is also entirely possible that oldererectus bones await discovery in africa。 in addition； the javan dates could be wrongaltogether。
now for the doubts。 some authorities don鈥檛 believe that the turkana finds are homoerectus at all。 the snag； ironically； was that although the turkana skeletons were admirablyextensive； all othererectus fossils are inconclusively fragmentary。 as tattersall and jeffreyschwartz note in extinct humans； most of the turkana skeleton 鈥渃ouldn鈥檛 be pared withanything else closely related to it because the parable parts weren鈥檛 known！鈥潯he turkanaskeletons； they say； look nothing like any asian homo erectus and would never have beenconsidered the same species except that they were contemporaries。 some authorities insist oncalling the turkana specimens （and any others from the same period） homo ergaster。
tattersall and schwartz don鈥檛 believe that goes nearly far enough。 they believe it wasergaster鈥渙r a reasonably close relative鈥潯hat spread to asia from africa； evolved intohomo erectus；and then died out。
what is certain is that sometime well over a million years ago； some new； parativelymodern； upright beings left africa and boldly spread out across much of the globe。 theypossibly did so quite rapidly； increasing their range by as much as twenty…five miles a year onaverage； all while dealing with mountain ranges； rivers； deserts； and other impediments andadapting to differences in climate and food sources。 a particular mystery is how they passedalong the west side of the red sea； an area of famously punishing aridity now； but even drierin the past。 it is a curious irony that the conditions that prompted them to leave africa wouldhave made it much more difficult to do so。 yet somehow they managed to find their wayaround every barrier and to thrive in the lands beyond。
and that； i鈥檓 afraid； is where all agreement ends。 what happened next in the history ofhuman development is a matter of long and rancorous debate； as we shall see in the nextchapter。
but it is worth remembering； before we move on； that all of these evolutionary jostlingsover five million years； from distant； puzzled australopithecine to fully modern human；produced a creature that is still 98。4 percent genetically indistinguishable from the modernchimpanzee。 there is more difference between a zebra and a horse； or between a dolphin anda porpoise； than there is between you and the furry creatures your distant ancestors left behindwhen they set out to take over the world。
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29 THE RESTLESS APESOME
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time about a million and a half years ago； some forgotten genius of the hominidworld did an unexpected thing。 he （or very possibly she） took one stone and carefully used itto shape another。 the result was a simple teardrop…shaped hand axe； but it was the world鈥檚first piece of advanced technology。
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