28    THE MYSTERIOUS BIPED

JUST BEFORE CHRISTMAS 1887, a young Dutch doctor with an un-Dutch name, MarieEugène Fran?ois Thomas Dubois, arrived in Sumatra, in the Dutch East Indies, with theintention of finding the earliest human remains on Earth.

1Several things were extraordinary about this. To begin with, no one had ever gone lookingfor ancient human bones before. Everything that had been found to this point had been foundaccidentally, and nothing in Dubois’s background suggested that he was the ideal candidate tomake the process intentional. He was an anatomist by training with no background inpaleontology. Nor was there any special reason to suppose that the East Indies would holdearly human remains. Logic dictated that if ancient people were to be found at all, it would beon a large and long-populated landmass, not in the comparative fastness of an archipelago.

Dubois was driven to the East Indies on nothing stronger than a hunch, the availability ofemployment, and the knowledge that Sumatra was full of caves, the environment in whichmost of the important hominid fossils had so far been found. What is most extraordinary in allthis—nearly miraculous, really—is that he found what he was looking for.

At the time Dubois conceived his plan to search for a missing link, the human fossil recordconsisted of very little: five incomplete Neandertal skeletons, one partial jawbone of uncertainprovenance, and a half-dozen ice-age humans recently found by railway workers in a cave at acliff called Cro-Magnon near Les Eyzies, France. Of the Neandertal specimens, the bestpreserved was sitting unremarked on a shelf in London. It had been found by workers blastingrock from a quarry in Gibraltar in 1848, so its preservation was a wonder, but unfortunatelyno one yet appreciated what it was. After being briefly described at a meeting of the GibraltarScientific Society, it had been sent to the Hunterian Museum in London, where it remainedundisturbed but for an occasional light dusting for over half a century. The first formaldescription of it wasn’t written until 1907, and then by a geologist named William Sollas“with only a passing competency in anatomy.”

So instead the name and credit for the discovery of the first early humans went to theNeander Valley in Germany—not unfittingly, as it happens, for by uncanny coincidenceNeander in Greek means “new man.” There in 1856 workmen at another quarry, in a cliff faceoverlooking the Düssel River, found some curious-looking bones, which they passed to alocal schoolteacher, knowing he had an interest in all things natural. To his great credit theteacher, Johann Karl Fuhlrott, saw that he had some new type of human, though quite what itwas, and how special, would be matters of dispute for some time.

Many people refused to accept that the Neandertal bones were ancient at all. August Mayer,a professor at the University of Bonn and a man of influence, insisted that the bones were1Though Dutch, Dubois was from Eijsden, a town bordering the French-speaking part of Belgium.

merely those of a Mongolian Cossack soldier who had been wounded while fighting inGermany in 1814 and had crawled into the cave to die. Hearing of this, T. H. Huxley inEngland drily observed how remarkable it was that the soldier, though mortally wounded, hadclimbed sixty feet up a cliff, divested himself of his clothing and personal effects, sealed thecave opening, and buried himself under two feet of soil. Another anthropologist, puzzlingover the Neandertal’s heavy brow ridge, suggested that it was the result of long-term frowningarising from a poorly healed forearm fracture. (In their eagerness to reject the idea of earlierhumans, authorities were often willing to embrace the most singular possibilities. At about thetime that Dubois was setting out for Sumatra, a skeleton found in Périgueux was confidentlydeclared to be that of an Eskimo. Quite what an ancient Eskimo was doing in southwestFrance was never comfortably explained. It was actually an early Cro-Magnon.)It was against this background that Dubois began his search for ancient human bones. Hedid no digging himself, but instead used fifty convicts lent by the Dutch authorities. For a yearthey worked on Sumatra, then transferred to Java. And there in 1891, Dubois—or rather histeam, for Dubois himself seldom visited the sites—found a section of ancient human craniumnow known as the Trinil skullcap. Though only part of a skull, it showed that the owner hadhad distinctly nonhuman features but a much larger brain than any ape. Dubois called itAnthropithecus erectus (later changed for technical reasons to Pithecanthropus erectus) anddeclared it the missing link between apes and humans. It quickly became popularized as “JavaMan.” Today we know it as Homo erectus.

The next year Dubois’s workers found a virtually complete thighbone that lookedsurprisingly modern. In fact, many anthropologists think itis modern, and has nothing to dowith Java Man. If it is an erectus bone, it is unlike any other found since. Nonetheless Duboisused the thighbone to deduce—correctly, as it turned out—that Pithecanthropus walkedupright. He also produced, with nothing but a scrap of cranium and one tooth, a model of thecomplete skull, which also proved uncannily accurate.

In 1895, Dubois returned to Europe, expecting a triumphal reception. In fact, he met nearlythe opposite reaction. Most scientists disliked both his conclusions and the arrogant manner inwhich he presented them. The skullcap, they said, was that of an ape, probably a gibbon, andnot of any early human. Hoping to bolster his case, in 1897 Dubois allowed a respectedanatomist from the University of Strasbourg, Gustav Schwalbe, to make a cast of the skullcap.

To Dubois’s dismay, Schwalbe thereupon produced a monograph that received far moresympathetic attention than anything Dubois had written and followed with a lecture tour inwhich he was celebrated nearly as warmly as if he had dug up the skull himself. Appalled andembittered, Dubois withdrew into an undistinguished position as a professor of geology at theUniversity of Amsterdam and for the next two decades refused to let anyone examine hisprecious fossils again. He died in 1940 an unhappy man.

Meanwhile, and half a world away, in late 1924 Raymond Dart, the Australian-born head ofanatomy at the University of the Witwatersrand in Johannesburg, was sent a small butremarkably complete skull of a child, with an intact face, a lower jaw, and what is known asan endocast—a natural cast of the brain—from a limestone quarry on the edge of the KalahariDesert at a dusty spot called Taung. Dart could see at once that the Taung skull was not of aHomo erectus like Dubois’s Java Man, but from an earlier, more apelike creature. He placedits age at two million years and dubbed it Australopithecus africanus, or “southern ape man ofAfrica.” In a report to Nature, Dart called the Taung remains “amazingly human” andsuggested the need for an entirely new family, Homo simiadae (“the man-apes”), toaccommodate the find.

The authorities were even less favorably disposed to Dart than they had been to Dubois.

Nearly everything about his theory—indeed, nearly everything about Dart, it appears—annoyed them. First he had proved himself lamentably presumptuous by conducting theanalysis himself rather than calling on the help of more worldly experts in Europe. Even hischosen name, Australopithecus, showed a lack of scholarly application, combining as it didGreek and Latin roots. Above all, his conclusions flew in the face of accepted wisdom.

Humans and apes, it was agreed, had split apart at least fifteen million years ago in Asia. Ifhumans had arisen in Africa, why, that would make us Negroid, for goodness sake. It wasrather as if someone working today were to announce that he had found the ancestral bones ofhumans in, say, Missouri. It just didn’t fit with what was known.

Dart’s sole supporter of note was Robert Broom, a Scottish-born physician andpaleontologist of considerable intellect and cherishably eccentric nature. It was Broom’shabit, for instance, to do his fieldwork naked when the weather was warm, which was often.

He was also known for conducting dubious anatomical experiments on his poorer and moretractable patients. When the patients died, which was also often, he would sometimes burytheir bodies in his back garden to dig up for study later.

Broom was an accomplished paleontologist, and since he was also resident in South Africahe was able to examine the Taung skull at first hand. He could see at once that it was asimportant as Dart supposed and spoke out vigorously on Dart’s behalf, but to no effect. Forthe next fifty years the received wisdom was that the Taung child was an ape and nothingmore. Most textbooks didn’t even mention it. Dart spent five years working up a monograph,but could find no one to publish it. Eventually he gave up the quest to publish altogether(though he did continue hunting for fossils). For years, the skull—today recognized as one ofthe supreme treasures of anthropology—sat as a paperweight on a colleague’s desk.

At the time Dart made his announcement in 1924, only four categories of ancient hominidwere known—Homo heidelbergensis, Homo rhodesiensis, Neandertals, and Dubois’s JavaMan—but all that was about to change in a very big way.

First, in China, a gifted Canadian amateur named Davidson Black began to poke around ata place, Dragon Bone Hill, that was locally famous as a hunting ground for old bones.

Unfortunately, rather than preserving the bones for study, the Chinese ground them up tomake medicines. We can only guess how many priceless Homo erectus bones ended up as asort of Chinese equivalent of bicarbonate of soda. The site had been much denuded by thetime Black arrived, but he found a single fossilized molar and on the basis of that alone quitebrilliantly announced the discovery of Sinanthropus pekinensis, which quickly became knownas Peking Man.

At Black’s urging, more determined excavations were undertaken and many other bonesfound. Unfortunately all were lost the day after the Japanese attack on Pearl Harbor in 1941when a contingent of U.S. Marines, trying to spirit the bones (and themselves) out of thecountry, was intercepted by the Japanese and imprisoned. Seeing that their crates held nothingbut bones, the Japanese soldiers left them at the roadside. It was the last that was ever seen ofthem.

In the meantime, back on Dubois’s old turf of Java, a team led by Ralph von Koenigswaldhad found another group of early humans, which became known as the Solo People from thesite of their discovery on the Solo River at Ngandong. Koenigswald’s discoveries might havebeen more impressive still but for a tactical error that was realized too late. He had offeredlocals ten cents for every piece of hominid bone they could come up with, then discovered tohis horror that they had been enthusiastically smashing large pieces into small ones tomaximize their income.

In the following years as more bones were found and identified there came a flood of newnames—Homo aurignacensis, Australopithecus transvaalensis, Paranthropus crassidens,Zinjanthropus boisei,and scores of others, nearly all involving a new genus type as well as anew species. By the 1950s, the number of named hominid types had risen to comfortably overa hundred. To add to the confusion, individual forms often went by a succession of differentnames as paleoanthropologists refined, reworked, and squabbled over classifications. SoloPeople were known variously as Homo soloensis, Homo primigenius asiaticus, Homoneanderthalensis soloensis, Homo sapiens soloensis, Homo erectus erectus, and, finally, plainHomo erectus .

In an attempt to introduce some order, in 1960 F. Clark Howell of the University ofChicago, following the suggestions of Ernst Mayr and others the previous decade, proposedcutting the number of genera to just two—Australopithecus and Homo —and rationalizingmany of the species. The Java and Peking men both became Homo erectus. For a time orderprevailed in the world of the hominids.

2It didn’t last.

After about a decade of comparative calm, paleoanthropology embarked on another periodof swift and prolific discovery, which hasn’t abated yet. The 1960s produced Homo habilis,thought by some to be the missing link between apes and humans, but thought by others not tobe a separate species at all. Then came (among many others) Homo ergaster, Homolouisleakeyi, Homo rudolfensis, Homo microcranus, and Homo antecessor, as well as a raft ofaustralopithecines: A.afarensis, A. praegens, A. ramidus, A. walkeri, A. anamensis, and stillothers. Altogether, some twenty types of hominid are recognized in the literature today.

Unfortunately, almost no two experts recognize the same twenty.

Some continue to observe the two hominid genera suggested by Howell in 1960, but othersplace some of the australopithecines in a separate genus called Paranthropus , and still othersadd an earlier group called Ardipithecus. Some put praegens into Australopithecus and someinto a new classification, Homo antiquus, but most don’t recognize praegens as a separatespecies at all. There is no central authority that rules on these things. The only way a namebecomes accepted is by consensus, and there is often very little of that.

A big part of the problem, paradoxically, is a shortage of evidence. Since the dawn of time,several billion human (or humanlike) beings have lived, each contributing a little geneticvariability to the total human stock. Out of this vast number, the whole of our understandingof human prehistory is based on the remains, often exceedingly fragmentary, of perhaps fivethousand individuals. “You could fit it all into the back of a pickup truck if you didn’t mind2Humans are put in the lamely Homimdae. Its members, traditionally called hominids, include any creatures(including extinct ones) that are more closely related to us than to any surviving chimpanzees. The apes,meanwhile, are lumped together in a family called Pongidae. Many authorities believe that chimps, gorillas, andorangutans should also be included in this family, with humans and chimps in a subfamily called Homininae.

The upshot is that the creatures traditionally called hominids become, under this arrangement, hominins. (Leakeyand others insist on that designation.) Hominoidea is the name of the aue sunerfamily which includes us.

how much you jumbled everything up,” Ian Tattersall, the bearded and friendly curator ofanthropology at the American Museum of Natural History in New York, replied when I askedhim the size of the total world archive of hominid and early human bones.

The shortage wouldn’t be so bad if the bones were distributed evenly through time andspace, but of course they are not. They appear randomly, often in the most tantalizing fashion.

Homo erectus walked the Earth for well over a million years and inhabited territory from theAtlantic edge of Europe to the Pacific side of China, yet if you brought back to life everyHomo erectus individual whose existence we can vouch for, they wouldn’t fill a school bus.

Homo habilis consists of even less: just two partial skeletons and a number of isolated limbbones. Something as short-lived as our own civilization would almost certainly not be knownfrom the fossil record at all.

“In Europe,” Tattersall offers by way of illustration, “you’ve got hominid skulls in Georgiadated to about 1.7 million years ago, but then you have a gap of almost a million years beforethe next remains turn up in Spain, right on the other side of the continent, and then you’ve gotanother 300,000-year gap before you get a Homo heidelbergensis in Germany—and none ofthem looks terribly much like any of the others.” He smiled. “It’s from these kinds offragmentary pieces that you’re trying to work out the histories of entire species. It’s quite atall order. We really have very little idea of the relationships between many ancient species—which led to us and which were evolutionary dead ends. Some probably don’t deserve to beregarded as separate species at all.”

It is the patchiness of the record that makes each new find look so sudden and distinct fromall the others. If we had tens of thousands of skeletons distributed at regular intervals throughthe historical record, there would be appreciably more degrees of shading. Whole new speciesdon’t emerge instantaneously, as the fossil record implies, but gradually out of other, existingspecies. The closer you go back to a point of divergence, the closer the similarities are, so thatit becomes exceedingly difficult, and sometimes impossible, to distinguish a late Homoerectus from an early Homo sapiens, since it is likely to be both and neither. Similardisagreements can often arise over questions of identification from fragmentary remains—deciding, for instance, whether a particular bone represents a female Australopithecus boiseior a male Homo habilis.

With so little to be certain about, scientists often have to make assumptions based on otherobjects found nearby, and these may be little more than valiant guesses. As Alan Walker andPat Shipman have drily observed, if you correlate tool discovery with the species of creaturemost often found nearby, you would have to conclude that early hand tools were mostly madeby antelopes.

Perhaps nothing better typifies the confusion than the fragmentary bundle of contradictionsthat was Homo habilis. Simply put, habilis bones make no sense. When arranged in sequence,they show males and females evolving at different rates and in different directions—the malesbecoming less apelike and more human with time, while females from the same period appearto be moving away from humanness toward greater apeness. Some authorities don’t believehabilis is a valid category at all. Tattersall and his colleague Jeffrey Schwartz dismiss it as amere “wastebasket species”—one into which unrelated fossils “could be conveniently swept.”

Even those who see habilis as an independent species don’t agree on whether it is of the samegenus as us or is from a side branch that never came to anything.

Finally, but perhaps above all, human nature is a factor in all this. Scientists have a naturaltendency to interpret finds in the way that most flatters their stature. It is a rare paleontologistindeed who announces that he has found a cache of bones but that they are nothing to getexcited about. Or as John Reader understatedly observes in the book Missing Links, “It isremarkable how often the first interpretations of new evidence have confirmed thepreconceptions of its discoverer.”

All this leaves ample room for arguments, of course, and nobody likes to argue more thanpaleoanthropologists. “And of all the disciplines in science, paleoanthropology boasts perhapsthe largest share of egos,” say the authors of the recent Java Man —a book, it may be noted,that itself devotes long, wonderfully unselfconscious passages to attacks on the inadequaciesof others, in particular the authors’ former close colleague Donald Johanson. Here is a smallsampling:

In our years of collaboration at the institute he [Johanson] developed a well-deserved, if unfortunate, reputation for unpredictable and high-decibel personalverbal assaults, sometimes accompanied by the tossing around of books orwhatever else came conveniently to hand.

So, bearing in mind that there is little you can say about human prehistory that won’t bedisputed by someone somewhere, other than that we most certainly had one, what we thinkwe know about who we are and where we come from is roughly this:

For the first 99.99999 percent of our history as organisms, we were in the same ancestralline as chimpanzees. Virtually nothing is known about the prehistory of chimpanzees, butwhatever they were, we were. Then about seven million years ago something major happened.

A group of new beings emerged from the tropical forests of Africa and began to move abouton the open savanna.

These were the australopithecines, and for the next five million years they would be theworld’s dominant hominid species. (Austral is from the Latin for “southern” and has noconnection in this context to Australia.) Australopithecines came in several varieties, someslender and gracile, like Raymond Dart’s Taung child, others more sturdy and robust, but allwere capable of walking upright. Some of these species existed for well over a million years,others for a more modest few hundred thousand, but it is worth bearing in mind that even theleast successful had histories many times longer than we have yet achieved.

The most famous hominid remains in the world are those of a 3.18-million-year-oldaustralopithecine found at Hadar in Ethiopia in 1974 by a team led by Donald Johanson.

Formally known as A.L. (for “Afar Locality”) 288–1, the skeleton became more familiarlyknown as Lucy, after the Beatles song “Lucy in the Sky with Diamonds.” Johanson has neverdoubted her importance. “She is our earliest ancestor, the missing link between ape andhuman,” he has said.

Lucy was tiny—just three and a half feet tall. She could walk, though how well is a matterof some dispute. She was evidently a good climber, too. Much else is unknown. Her skull wasalmost entirely missing, so little could be said with confidence about her brain size, thoughskull fragments suggested it was small. Most books describe Lucy’s skeleton as being 40percent complete, though some put it closer to half, and one produced by the AmericanMuseum of Natural History describes Lucy as two-thirds complete. The BBC television seriesApe Man actually called it “a complete skeleton,” even while showing that it was anythingbut.

A human body has 206 bones, but many of these are repeated. If you have the left femurfrom a specimen, you don’t need the right to know its dimensions. Strip out all the redundantbones, and the total you are left with is 120—what is called a half skeleton. Even by this fairlyaccommodating standard, and even counting the slightest fragment as a full bone, Lucyconstituted only 28 percent of a half skeleton (and only about 20 percent of a full one).

In The Wisdom of the Bones, Alan Walker recounts how he once asked Johanson how hehad come up with a figure of 40 percent. Johanson breezily replied that he had discounted the106 bones of the hands and feet—more than half the body’s total, and a fairly important half,too, one would have thought, since Lucy’s principal defining attribute was the use of thosehands and feet to deal with a changing world. At all events, rather less is known about Lucythan is generally supposed. It isn’t even actually known that she was a female. Her sex ismerely presumed from her diminutive size.

Two years after Lucy’s discovery, at Laetoli in Tanzania Mary Leakey found footprints leftby two individuals from—it is thought—the same family of hominids. The prints had beenmade when two australopithecines had walked through muddy ash following a volcaniceruption. The ash had later hardened, preserving the impressions of their feet for a distance ofover twenty-three meters.

The American Museum of Natural History in New York has an absorbing diorama thatrecords the moment of their passing. It depicts life-sized re-creations of a male and a femalewalking side by side across the ancient African plain. They are hairy and chimplike indimensions, but have a bearing and gait that suggest humanness. The most striking feature ofthe display is that the male holds his left arm protectively around the female’s shoulder. It is atender and affecting gesture, suggestive of close bonding.

The tableau is done with such conviction that it is easy to overlook the consideration thatvirtually everything above the footprints is imaginary. Almost every external aspect of thetwo figures—degree of hairiness, facial appendages (whether they had human noses or chimpnoses), expressions, skin color, size and shape of the female’s breasts—is necessarilysuppositional. We can’t even say that they were a couple. The female figure may in fact havebeen a child. Nor can we be certain that they were australopithecines. They are assumed to beaustralopithecines because there are no other known candidates.

I had been told that they were posed like that because during the building of the dioramathe female figure kept toppling over, but Ian Tattersall insists with a laugh that the story isuntrue. “Obviously we don’t know whether the male had his arm around the female or not,but we do know from the stride measurements that they were walking side by side and closetogether—close enough to be touching. It was quite an exposed area, so they were probablyfeeling vulnerable. That’s why we tried to give them slightly worried expressions.”

I asked him if he was troubled about the amount of license that was taken in reconstructingthe figures. “It’s always a problem in making re-creations,” he agreed readily enough. “Youwouldn’t believe how much discussion can go into deciding details like whether Neandertalshad eyebrows or not. It was just the same for the Laetoli figures. We simply can’t know thedetails of what they looked like, but we can convey their size and posture and make somereasonable assumptions about their probable appearance. If I had it to do again, I think I mighthave made them just slightly more apelike and less human. These creatures weren’t humans.

They were bipedal apes.”

Until very recently it was assumed that we were descended from Lucy and the Laetolicreatures, but now many authorities aren’t so sure. Although certain physical features (theteeth, for instance) suggest a possible link between us, other parts of the australopithecineanatomy are more troubling. In their book Extinct Humans, Tattersall and Schwartz point outthat the upper portion of the human femur is very like that of the apes but not of theaustralopithecines; so if Lucy is in a direct line between apes and modern humans, it meanswe must have adopted an australopithecine femur for a million years or so, then gone back toan ape femur when we moved on to the next phase of our development. They believe, in fact,that not only was Lucy not our ancestor, she wasn’t even much of a walker.

“Lucy and her kind did not locomote in anything like the modern human fashion,” insistsTattersall. “Only when these hominids had to travel between arboreal habitats would they findthemselves walking bipedally, ‘forced’ to do so by their own anatomies.” Johanson doesn’taccept this. “Lucy’s hips and the muscular arrangement of her pelvis,” he has written, “wouldhave made it as hard for her to climb trees as it is for modern humans.”

Matters grew murkier still in 2001 and 2002 when four exceptional new specimens werefound. One, discovered by Meave Leakey of the famous fossil-hunting family at LakeTurkana in Kenya and called Kenyanthropus platyops (“Kenyan flat-face”), is from about thesame time as Lucy and raises the possibility that it was our ancestor and Lucy was anunsuccessful side branch. Also found in 2001 were Ardipithecus ramidus kadabba, dated atbetween 5.2 million and 5.8 million years old, and Orrorin tugenensis, thought to be 6 millionyears old, making it the oldest hominid yet found—but only for a brief while. In the summerof 2002 a French team working in the Djurab Desert of Chad (an area that had never beforeyielded ancient bones) found a hominid almost 7 million years old, which they labeledSahelanthropus tchadensis. (Some critics believe that it was not human, but an early ape andtherefore should be called Sahelpithecus.) All these were early creatures and quite primitivebut they walked upright, and they were doing so far earlier than previously thought.

Bipedalism is a demanding and risky strategy. It means refashioning the pelvis into a fullload-bearing instrument. To preserve the required strength, the birth canal must becomparatively narrow. This has two very significant immediate consequences and one longer-term one. First, it means a lot of pain for any birthing mother and a greatly increased dangerof fatality to mother and baby both. Moreover to get the baby’s head through such a tightspace it must be born while its brain is still small—and while the baby, therefore, is stillhelpless. This means long-term infant care, which in turn implies solid male–female bonding.

All this is problematic enough when you are the intellectual master of the planet, but whenyou are a small, vulnerable australopithecine, with a brain about the size of an orange,3therisk must have been enormous.

3Absolute brain size does not tell you everything-or possibly sometimes even much. Elephants and whales bothhave brains larger than ours, but you wouldnt have much trouble outwitting them in contract negotiations. It isrelative size that matters, a point that is often overlooked. As Gould notes, A. africanus had a brain of only 450cubic centimeters, smaller than that of a gorilla. But a typical africanus male weighed less than a hundredpounds, and a female much less still, whereas gorillas can easily top out at 600 pounds (Gould pp. 181-83).

So why did Lucy and her kind come down from the trees and out of the forests? Probablythey had no choice. The slow rise of the Isthmus of Panama had cut the flow of waters fromthe Pacific into the Atlantic, diverting warming currents away from the Arctic and leading tothe onset of an exceedingly sharp ice age in northern latitudes. In Africa, this would haveproduced seasonal drying and cooling, gradually turning jungle into savanna. “It was not somuch that Lucy and her like left the forests,” John Gribbin has written, “but that the forestsleft them.”

But stepping out onto the open savanna also clearly left the early hominids much moreexposed. An upright hominid could see better, but could also be seen better. Even now as aspecies, we are almost preposterously vulnerable in the wild. Nearly every large animal youcan care to name is stronger, faster, and toothier than us. Faced with attack, modern humanshave only two advantages. We have a good brain, with which we can devise strategies, andwe have hands with which we can fling or brandish hurtful objects. We are the only creaturethat can harm at a distance. We can thus afford to be physically vulnerable.

All the elements would appear to have been in place for the rapid evolution of a potentbrain, and yet that seems not to have happened. For over three million years, Lucy and herfellow australopithecines scarcely changed at all. Their brain didn’t grow and there is no signthat they used even the simplest tools. What is stranger still is that we now know that forabout a million years they lived alongside other early hominids who did use tools, yet theaustralopithecines never took advantage of this useful technology that was all around them.

At one point between three and two million years ago, it appears there may have been asmany as six hominid types coexisting in Africa. Only one, however, was fated to last: Homo,which emerged from the mists beginning about two million years ago. No one knows quitewhat the relationship was between australopithecines and Homo, but what is known is thatthey coexisted for something over a million years before all the australopithecines, robust andgracile alike, vanished mysteriously, and possibly abruptly, over a million years ago. No oneknows why they disappeared. “Perhaps,” suggests Matt Ridley, “we ate them.”

Conventionally, the Homo line begins with Homo habilis, a creature about whom we knowalmost nothing, and concludes with us, Homo sapiens (literally “man the thinker”). Inbetween, and depending on which opinions you value, there have been half a dozen otherHomo species: Homo ergaster, Homo neanderthalensis, Homo rudolfensis, Homoheidelbergensis, Homo erectus, and Homo antecessor.

Homo habilis (“handy man”) was named by Louis Leakey and colleagues in 1964 and wasso called because it was the first hominid to use tools, albeit very simple ones. It was a fairlyprimitive creature, much more chimpanzee than human, but its brain was about 50 percentlarger than that of Lucy in gross terms and not much less large proportionally, so it was theEinstein of its day. No persuasive reason has ever been adduced for why hominid brainssuddenly began to grow two million years ago. For a long time it was assumed that big brainsand upright walking were directly related—that the movement out of the forests necessitatedcunning new strategies that fed off of or promoted braininess—so it was something of asurprise, after the repeated discoveries of so many bipedal dullards, to realize that there wasno apparent connection between them at all.

“There is simply no compelling reason we know of to explain why human brains gotlarge,” says Tattersall. Huge brains are demanding organs: they make up only 2 percent of thebody’s mass, but devour 20 percent of its energy. They are also comparatively picky in whatthey use as fuel. If you never ate another morsel of fat, your brain would not complainbecause it won’t touch the stuff. It wants glucose instead, and lots of it, even if it means short-changing other organs. As Guy Brown notes: “The body is in constant danger of beingdepleted by a greedy brain, but cannot afford to let the brain go hungry as that would rapidlylead to death.” A big brain needs 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—even if you ran it backonly a relatively short way to the dawn of hominids—the chances are “quite unlikely” thatmodern humans or anything like them would be here now.

“One of the hardest ideas for humans to accept,” he says, “is 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.” Indeed, 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—each 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’t come to anything.

Luckily for us, one did—a 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 Eugène 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 complex tools, the first toleave evidence of campsites, the first to look after the weak and frail. Compared 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 “the velociraptor of its day,” according to Alan Walker of Penn StateUniversity and one of the world’s leading authorities. If you were to look one in the eyes, itmight appear superficially to be human, but “you wouldn’t connect. You’d be prey.”

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—not enough to come even close to making one full skeleton. So it wasn’tuntil an extraordinary discovery in Africa in the 1980s that its importance—or, at the veryleast, possible importance—as 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’s 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’s 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’s instincts and to their astonishment found a nearly complete Homo erectusskeleton. It was from a boy aged between about nine and twelve who had died 1.54 millionyears ago. The skeleton had “an entirely modern body structure,” says Tattersall, in a way thatwas without precedent. The Turkana boy was “very emphatically one of us.”

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 complexthan previously thought. The woman’s bones were deformed and covered in coarse growths,the result of an agonizing condition called hypervitaminosis A, which can come 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’s area, a region of the frontal lobe of the brain associated with speech.

Chimps don’t have such a feature. Alan Walker thinks the spinal canal didn’t have the sizeand complexity to enable speech, that they probably would have communicated 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—whichwould 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’t 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 “couldn’t be compared withanything else closely related to it because the comparable parts weren’t known!” The 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’t believe that goes nearly far enough. They believe it wasergaster“or a reasonably close relative” that 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, comparativelymodern, 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’m 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.