by Bill Bryson
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 the analysis himself rather than calling on the help of more worldly experts in Europe. Even his chosen name, Australopithecus , showed a lack of scholarly application, combining as it did Greek 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. If humans had arisen in Africa, why, that would make us Negroid , for goodness sake. It was rather as if someone working today were to announce that he had found the ancestral bones of humans 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 and paleontologist of considerable intellect and cherishably eccentric nature. It was Broom's habit, 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 more tractable patients. When the patients died, which was also often, he would sometimes bury their bodies in his back garden to dig up for study later.
Broom was an accomplished paleontologist, and since he was also resident in South Africa he was able to examine the Taung skull at first hand. He could see at once that it was as important as Dart supposed and spoke out vigorously on Dart's behalf, but to no effect. For the next fifty years the received wisdom was that the Taung child was an ape and nothing more. 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 of the 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 hominid were known-- Homo heidelbergensis, Homo rhodesiensis , Neandertals, and Dubois's Java Man--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 at a 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 to make medicines. We can only guess how many priceless Homo erectus bones ended up as a sort of Chinese equivalent of bicarbonate of soda. The site had been much denuded by the time Black arrived, but he found a single fossilized molar and on the basis of that alone quite brilliantly announced the discovery of Sinanthropus pekinensis , which quickly became known as Peking Man.
At Black's urging, more determined excavations were undertaken and many other bones found. Unfortunately all were lost the day after the Japanese attack on Pearl Harbor in 1941 when a contingent of U.S. Marines, trying to spirit the bones (and themselves) out of the country, was intercepted by the Japanese and imprisoned. Seeing that their crates held nothing but bones, the Japanese soldiers left them at the roadside. It was the last that was ever seen of them.
In the meantime, back on Dubois's old turf of Java, a team led by Ralph von Koenigswald had found another group of early humans, which became known as the Solo People from the site of their discovery on the Solo River at Ngandong. Koenigswald's discoveries might have been more impressive still but for a tactical error that was realized too late. He had offered locals ten cents for every piece of hominid bone they could come up with, then discovered to his horror that they had been enthusiastically smashing large pieces into small ones to maximize their income.
In the following years as more bones were found and identified there came a flood of new names-- Homo aurignacensis, Australopithecus transvaalensis, Paranthropus crassidens, Zinjanthropus boisei, and scores of others, nearly all involving a new genus type as well as a new species. By the 1950s, the number of named hominid types had risen to comfortably over a hundred. To add to the confusion, individual forms often went by a succession of different names as paleoanthropologists refined, reworked, and squabbled over classifications. Solo People were known variously as Homo soloensis, Homo primigenius asiaticus, Homo neanderthalensis soloensis, Homo sapiens soloensis, Homo erectus erectus, and, finally, plain Homo erectus .
In an attempt to introduce some order, in 1960 F. Clark Howell of the University of Chicago, following the suggestions of Ernst Mayr and others the previous decade, proposed cutting the number of genera to just two-- Australopithecus and Homo --and rationalizing many of the species. The Java and Peking men both became Homo erectus . For a time order prevailed in the world of the hominids. * 47 It didn't last.
After about a decade of comparative calm, paleoanthropology embarked on another period of 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 to be a separate species at all. Then came (among many others) Homo ergaster, Homo louisleakeyi, Homo rudolfensis, Homo microcranus, and Homo antecessor , as well as a raft of australopithecines: A. afarensis, A. praegens, A. ramidus, A. walkeri, A. anamensis , and still others. 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 others place some of the australopithecines in a separate genus called Paranthropus , and still others add an earlier group called Ardipithecus . Some put praegens into Australopithecus and some into a new classification, Homo antiquus , but most don't recognize praegens as a separate species at all. There is no central authority that rules on these things. The only way a name becomes 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 genetic variability to the total human stock. Out of this vast number, the whole of our understanding of human prehistory is based on the remains, often exceedingly fragmentary, of perhaps five thousand individuals. "You could fit it all into the back of a pickup truck if you didn't mind how much you jumbled everything up," Ian Tattersall, the bearded and friendly curator of anthropology at the American Museum of Natural History in New York, replied when I asked him 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 and space, 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 the Atlantic edge of Europe to the Pacific side of China, yet if you brought back to life every Homo 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 limb bones. Something as short-lived as our own civilization would almost certainly not be known from the fossil record at all.
"In Europe," Tattersall offers by way of illustration, "you've got hominid skulls in Georgia dated to about 1.7 million years ago, but then you have a gap of almost a million years before the next remains turn up in Spain, right on the other side of the continent, and then you've got another 300,000-year gap before you get a Homo heidelbergensis in Germany--and none of them looks terribly much like any of the others." He smiled. "It's from these kinds of fragmentary pieces that you're trying to work out the histories of entire species. It's quite a tall 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 be regarded as separate species at all."
It is the patchiness of the record that makes each new find look so sudden and distinct from all the others. If we had tens of thousands of skeletons distributed at regular inter
vals through the historical record, there would be appreciably more degrees of shading. Whole new species don't emerge instantaneously, as the fossil record implies, but gradually out of other, existing species. The closer you go back to a point of divergence, the closer the similarities are, so that it becomes exceedingly difficult, and sometimes impossible, to distinguish a late Homo erectus from an early Homo sapiens , since it is likely to be both and neither. Similar disagreements can often arise over questions of identification from fragmentary remains--deciding, for instance, whether a particular bone represents a female Australopithecus boisei or a male Homo habilis .
With so little to be certain about, scientists often have to make assumptions based on other objects found nearby, and these may be little more than valiant guesses. As Alan Walker and Pat Shipman have drily observed, if you correlate tool discovery with the species of creature most often found nearby, you would have to conclude that early hand tools were mostly made by antelopes.
Perhaps nothing better typifies the confusion than the fragmentary bundle of contradictions that 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 males becoming less apelike and more human with time, while females from the same period appear to be moving away from humanness toward greater apeness. Some authorities don't believe habilis is a valid category at all. Tattersall and his colleague Jeffrey Schwartz dismiss it as a mere "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 same genus 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 natural tendency to interpret finds in the way that most flatters their stature. It is a rare paleontologist indeed who announces that he has found a cache of bones but that they are nothing to get excited about. Or as John Reader understatedly observes in the book Missing Links , "It is remarkable how often the first interpretations of new evidence have confirmed the preconceptions of its discoverer."
All this leaves ample room for arguments, of course, and nobody likes to argue more than paleoanthropologists. "And of all the disciplines in science, paleoanthropology boasts perhaps the 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 inadequacies of others, in particular the authors' former close colleague Donald Johanson. Here is a small sampling:
In our years of collaboration at the institute he [Johanson] developed a well-deserved, if unfortunate, reputation for unpredictable and high-decibel personal verbal assaults, sometimes accompanied by the tossing around of books or whatever else came conveniently to hand.
So, bearing in mind that there is little you can say about human prehistory that won't be disputed by someone somewhere, other than that we most certainly had one, what we think we 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 ancestral line as chimpanzees. Virtually nothing is known about the prehistory of chimpanzees, but whatever 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 about on the open savanna.
These were the australopithecines, and for the next five million years they would be the world's dominant hominid species. ( Austral is from the Latin for "southern" and has no connection in this context to Australia.) Australopithecines came in several varieties, some slender and gracile, like Raymond Dart's Taung child, others more sturdy and robust, but all were 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 the least 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-old australopithecine 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 familiarly known as Lucy, after the Beatles song "Lucy in the Sky with Diamonds." Johanson has never doubted her importance. "She is our earliest ancestor, the missing link between ape and human," he has said.
Lucy was tiny--just three and a half feet tall. She could walk, though how well is a matter of some dispute. She was evidently a good climber, too. Much else is unknown. Her skull was almost entirely missing, so little could be said with confidence about her brain size, though skull fragments suggested it was small. Most books describe Lucy's skeleton as being 40 percent complete, though some put it closer to half, and one produced by the American Museum 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 anything but.
A human body has 206 bones, but many of these are repeated. If you have the left femur from a specimen, you don't need the right to know its dimensions. Strip out all the redundant bones, and the total you are left with is 120--what is called a half skeleton. Even by this fairly accommodating standard, and even counting the slightest fragment as a full bone, Lucy constituted 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 he had come up with a figure of 40 percent. Johanson breezily replied that he had discounted the 106 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 those hands and feet to deal with a changing world. At all events, rather less is known about Lucy than is generally supposed. It isn't even actually known that she was a female. Her sex is merely presumed from her diminutive size.
Two years after Lucy's discovery, at Laetoli in Tanzania Mary Leakey found footprints left by two individuals from--it is thought--the same family of hominids. The prints had been made when two australopithecines had walked through muddy ash following a volcanic eruption. The ash had later hardened, preserving the impressions of their feet for a distance of over twenty-three meters.
The American Museum of Natural History in New York has an absorbing diorama that records the moment of their passing. It depicts life-sized re-creations of a male and a female walking side by side across the ancient African plain. They are hairy and chimplike in dimensions, but have a bearing and gait that suggest humanness. The most striking feature of the display is that the male holds his left arm protectively around the female's shoulder. It is a tender and affecting gesture, suggestive of close bonding.
The tableau is done with such conviction that it is easy to overlook the consideration that virtually everything above the footprints is imaginary. Almost every external aspect of the two figures--degree of hairiness, facial appendages (whether they had human noses or chimp noses), expressions, skin color, size and shape of the female's breasts--is necessarily suppositional. We can't even say that they were a couple. The female figure may in fact have been a child. Nor can we be certain that they were australopithecines. They are assumed to be australopithecines because there are no other known candidates.
I had been told that they were posed like that because during the building of the diorama the female figure kept toppling over, but Ian Tattersall insists with a laugh that the story is untrue. "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 close together--close enough to be touching. It was quite an exposed area, so they were probably feeling 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 reconstructing the figures. "It's alwa
ys a problem in making re-creations," he agreed readily enough. "You wouldn't believe how much discussion can go into deciding details like whether Neandertals had eyebrows or not. It was just the same for the Laetoli figures. We simply can't know the details of what they looked like, but we can convey their size and posture and make some reasonable 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 Laetoli creatures, but now many authorities aren't so sure. Although certain physical features (the teeth, for instance) suggest a possible link between us, other parts of the australopithecine anatomy are more troubling. In their book Extinct Humans , Tattersall and Schwartz point out that the upper portion of the human femur is very like that of the apes but not of the australopithecines; so if Lucy is in a direct line between apes and modern humans, it means we must have adopted an australopithecine femur for a million years or so, then gone back to an 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," insists Tattersall. "Only when these hominids had to travel between arboreal habitats would they find themselves walking bipedally, 'forced' to do so by their own anatomies." Johanson doesn't accept this. "Lucy's hips and the muscular arrangement of her pelvis," he has written, "would have made it as hard for her to climb trees as it is for modern humans."
