by Bill Bryson
The extraordinary fact is that we don’t know which is more likely: a future offering us aeons of perishing frigidity or one giving us equal expanses of steamy heat. Only one thing is certain: we live on a knife edge.
In the long run, incidentally, ice ages are by no means altogether bad news for the planet. They grind up rocks, leaving behind new soils of sumptuous richness, and gouge out freshwater lakes that provide abundant nutritive possibilities for hundreds of species of being. They act as a spur to migration and keep the planet dynamic. As Tim Flannery has remarked: “There is only one question you need ask of a continent in order to determine the fate of its people: ‘Did you have a good ice age?’” And with that in mind, it’s time to look at a species of ape that truly did.
Because ice sheets are mostly in remote places, we tend not to appreciate their massive extent. Altogether, permanent ice covers some six million square miles of the Earth's land—an area roughly the size of South America.
(Credit 27.12)
The haunting face of Homo erectus, recreated by the artist John Gurche. Considered by many to mark the dividing line between apelike beings and modern humans, Homo erectus was the first to hunt, use fire and look after the sick and frail, but it had the mind of a small child. Were you to run into one today, “you’d be prey,” according to the palaeontologist Alan Walker. (Credit 28.1)
THE MYSTERIOUS BIPED
Just before Christmas 1887, a young Dutch doctor with an un-Dutch name, Marie Eugène François Thomas Dubois,1 arrived in Sumatra, in the Dutch East Indies, with the intention of finding the earliest human remains on Earth.
Several things were extraordinary about this. To begin with, no-one had ever gone looking for ancient human bones before. Everything that had been found to this point had been found accidentally, and nothing in Dubois’ background suggested that he was the ideal candidate to make the process intentional. He was an anatomist by training with no background in palaeontology. Nor was there any special reason to suppose that the East Indies would hold early human remains. Logic dictated that if ancient people were to be found at all, it would be on a large and long-populated land mass, not in the comparative fastness of an archipelago. Dubois was driven to the East Indies on nothing stronger than a hunch, the availability of employment and the knowledge that Sumatra was full of caves, the environment in which most of the important hominid fossils had so far been found.2 What is most extraordinary in all this—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 record consisted of very little: five incomplete Neandertal skeletons, one partial jawbone of uncertain provenance and half a dozen ice-age humans recently found by railway workers in a cave at a cliff called Cro-Magnon near Les Eyzies, France. Of the Neandertal specimens, the best preserved was sitting unremarked on a shelf in London. It had been found by workers blasting rock from a quarry in Gibraltar in 1848, so its preservation was a wonder, but unfortunately no-one yet appreciated what it was. After being briefly described at a meeting of the Gibraltar Scientific Society, it had been sent to the Hunterian Museum, where it remained undisturbed but for an occasional light dusting for over half a century. The first formal description 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 the Neander valley in Germany—not unfittingly, as it happens, for by uncanny coincidence Neander in Greek means “new man.” There, in 1856, workmen at another quarry, in a cliff face overlooking the Düssel River, found some curious-looking bones, which they passed to a local schoolteacher, knowing he had an interest in all things natural. To his great credit the teacher, Johann Karl Fuhlrott, saw that he had some new type of human, though quite what it was, and how special, would be matters of dispute for some time.
The partial skull of a Neandertal woman shown in the cave in Krapina, Croatia, where it was discovered. Such remains are extremely rare. The entire stock of prehistoric hominid bones “wouldn’t fill the back of a pickup truck.” (Credit 28.2)
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 were merely those of a Mongolian Cossack soldier who had been wounded while fighting in Germany in 1814 and had crawled into the cave to die. Hearing of this, T. H. Huxley in England drily observed how remarkable it was that the soldier, though mortally wounded, had climbed 60 feet up a cliff, divested himself of his clothing and personal effects, sealed the cave opening and buried himself under 2 feet of soil. Another anthropologist, puzzling over the Neandertal’s heavy brow ridge, suggested that it was the result of long-term frowning arising from a poorly healed forearm fracture. (In their eagerness to reject the idea of earlier humans, authorities were often willing to embrace the most singular possibilities. At about the time that Dubois was setting out for Sumatra, a skeleton found in Périgueux was confidently declared to be that of an Eskimo. Quite what an ancient Eskimo was doing in southwest France 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. He did no digging himself, but instead used fifty convicts lent by the Dutch authorities. For a year they worked on Sumatra, then transferred to Java. And there in 1891, Dubois—or rather his team, for Dubois himself seldom visited the sites—found a section of ancient human cranium now known as the Trinil skullcap. Though only part of a skull, it showed that the owner had had distinctly non-human features but a much larger brain than any ape. Dubois called it Anthropithecus erectus (later changed for technical reasons to Pithecanthropus erectus) and declared it the missing link between apes and humans. It quickly became popularized as “Java Man.” Today we know it as Homo erectus.
Eugène Dubois, who set out in 1887 to find the earliest human remains on Earth. His unerring instinct led him in 1891 to find part of a human skull, which he declared the missing link between apes and humans. His human, popularized as “Java man,” is today known as Homo erectus. (Credit 28.3)
The next year Dubois’ workers found a virtually complete thighbone that looked surprisingly modern. In fact, many anthropologists think it is modern, and has nothing to do with Java Man. If it is an erectus bone, it is unlike any other found since. Nonetheless Dubois used the thighbone to deduce—correctly, as it turned out—that Pithecanthropus walked upright. He also produced, with nothing but a scrap of cranium and one tooth, a model of the complete skull, which also proved uncannily accurate.
In 1895 Dubois returned to Europe, expecting a triumphal reception. In fact, he met nearly the opposite reaction. Most scientists disliked both his conclusions and the arrogant manner in which he presented them. The skullcap, they said, was that of an ape, probably a gibbon, and not of any early human. Hoping to bolster his case, in 1897 Dubois allowed a respected anatomist from the University of Strasbourg, Gustav Schwalbe, to make a cast of the skullcap. To Dubois’ dismay, Schwalbe thereupon produced a monograph that received far more sympathetic attention than anything Dubois had written, and followed it with a lecture tour in which he was celebrated nearly as warmly as if he had dug up the skull himself. Appalled and embittered, Dubois withdrew into an undistinguished position as a professor of geology at the University of Amsterdam and for the next two decades refused to let anyone examine his precious fossils again. He died in 1940, an unhappy man.
Meanwhile, and half a world away, in late 1924 Raymond Dart, the Australian-born head of anatomy at the University of the Witwatersrand in Johannesburg, was sent a small but remarkably complete skull of a child, with an intact face, a lower jaw and what is known as an endocast—a natural cast of the brain—from a limestone quarry on the edge of the Kalahari Desert at a dusty spot called Taung. Dart could see at once that the Taung skull was not of a Hom
o erectus like Dubois’ Java Man, but from an earlier, more apelike creature. He placed its age at two million years and dubbed it Australopithecus africanus, or “southern ape man of Africa.” 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”), to accommodate the find.
The authorities were even less favourably disposed towards Dart than they had been to Dubois. Nearly everything about his theory—indeed, nearly everything about Dart, it appears—annoyed them. To start with, he had proved himself lamentably presumptuous by conducting the analysis himself rather than calling on the help of more worldly experts. 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 15 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 ancestral bones of humans in, say, Missouri. It just didn’t fit with what was known.
The Australian anatomist Raymond Dart photographed in 1978 with the skull of the primate he named Australopithecus africanus, which was discovered in South Africa in 1924. Dart’s claim that the specimen was an early hominid was widely rejected at the time. (Credit 28.4)
Dart’s sole supporter of note was Robert Broom, a Scottish-born physician and palaeontologist 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.
Robert Broom, eccentric but insightful palaeontologist, who supported the controversial findings of his colleague Raymond Dart. (Credit 28.4a)
Broom was an accomplished palaeontologist 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’ 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 called Dragon Bone Hill, which 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 Beecham’s powder. 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.
The bones, beaks and hooves displayed outside this native Chinese apothecary’s stall have been collected to be ground down into powder and used in medicines, a fate that has probably befallen many invaluable specimens of pre-human primates. (Credit 28.5)
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 US 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’ 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 10 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 palaeoanthropologists refined, reworked and squabbled over classifications. The 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. It didn’t last.
After about a decade of comparative calm, paleoanthropology embarked on another period of swift and numerous 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.
Seven skulls vividly convey the long road of human evolution. From left they are: Adapis (50 million years ago), Proconsul (23–15 million years), Australopithecus africanus (3 million years), Homo habilis (2 million years), Homo erectus (1 million years), early Homo sapiens (92,000 years) and Cro-Magnon (20,000 years ago). (Credit 28.6)
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 tantaliz
ing 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 three-hundred-thousand-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 intervals 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.
