Chapter Content
**Chapter 42: The Enigma of Bipedal Beings**
In the lead-up to Christmas of 1887, a young Dutch physician, bearing the decidedly un-Dutch name of Eugène Dubois, set sail for Sumatra, in the Dutch East Indies. His singular quest: to unearth the skeletal remains of the earliest humans to have walked the Earth. (It’s worth noting that Dubois, though Dutch, hailed from a small town – Egisheim - near the French-speaking border in Belgium.)
Dubois' endeavor was remarkable on several fronts. Firstly, no one before had deliberately sought out ancient human remains. Discoveries up until that point had been entirely accidental. Secondly, Dubois himself seemed an unlikely candidate to spearhead such a globally impactful pursuit. He was a trained anatomist, yes, but wholly unversed in the burgeoning field of paleontology. Furthermore, there was no particular reason to believe that the East Indies would hold the key to early human origins. Logically, one might expect to find such relics on the vast continents where human activity stretched back millennia, not on a relatively confined archipelago. Dubois’ motivations were a mixture of intuition, the promise of employment, and the fact that Sumatra possessed numerous caves – the kind of environment where many important hominid fossils had been previously discovered. And yet, against all odds, he found what he was looking for. A stroke of sheer, improbable fortune.
When Dubois conceived his plan to locate the "missing link" between apes and humans, the known fossil record of early humans was meager. It consisted of five incomplete Neanderthal skeletons, a fragment of a jawbone of uncertain provenance, and six Cro-Magnon skeletons, recently unearthed by railway workers in a cave at Les Eyzies, France. The most complete Neanderthal skeleton had, somewhat miraculously, survived demolition and was languishing, unregarded, on a shelf in London. Discovered in 1848 during quarrying operations near Gibraltar, it had been carelessly presented at a local scientific society meeting before being consigned to the Hunterian Museum in London, largely gathering dust for over half a century. A formal description wouldn’t come until 1907, penned by geologist William Sollas, whose anatomical qualifications were, shall we say, "less than stellar."
Thus, the Neander Valley in Germany lent its name – ironically, derived from the Greek for "new man" – to these pioneering human fossils. In 1856, laborers, once again at a quarry, this time along the Düssel River, stumbled upon a collection of peculiar bones. They handed them over to a local schoolteacher, Johann Karl Fuhlrott, knowing of his interest in all things natural. To Fuhlrott’s credit, he recognized the potential significance of the find, though what exactly it meant, and what kind of creature it represented, would be hotly debated for years to come.
Many refused to accept the Neanderthal remains as fossils of an ancient human. August Mayer, an influential professor at Bonn University, posited that they were merely the bones of a Mongolian Cossack soldier, wounded during the Napoleonic Wars in 1814, who had crawled into the cave to die. Upon hearing this, T.H. Huxley, in a fit of sarcasm, imagined the soldier dragging himself up a sixty foot cliff while gravely injured, divesting himself of his clothes and belongings, before burying himself in the cave and covering the entrance with dirt. Another anthropologist attributed the Neanderthal's prominent brow ridge to prolonged frowning resulting from a poorly healed broken arm (In their eagerness to dismiss early hominid theories, authorities often embraced wildly improbable explanations. Around the time Dubois set off for Sumatra, a skeleton found near Périgueux was confidently declared to be that of an Eskimo – with little explanation as to what a prehistoric Eskimo might have been doing in southwestern France. It turned out to be an early Cro-Magnon.)
It was against this backdrop of skepticism and scant evidence that Dubois embarked on his fossil hunt. He wouldn’t do the digging himself, instead employing fifty convicts borrowed from the Dutch authorities. After a year in Sumatra, the team moved to Java. It was there, in 1891, that Dubois – or rather, his team of diggers, as Dubois rarely visited the site himself – discovered a small piece of fossilized skull, now known as the Trinil skullcap. Though fragmentary, it was sufficient to suggest a creature that was not quite human, yet possessed a brain significantly larger than that of any ape. Dubois named it *Pithecanthropus erectus* (later amended to *Homo erectus* for technical reasons), and proclaimed it to be the missing link. It soon became popularly known as "Java Man." Today, we call it *Homo erectus.*
The following year, Dubois' workers unearthed an almost complete femur (thigh bone), strikingly similar to that of modern humans. Indeed, many anthropologists argued that it *was* a modern human bone and had nothing to do with Java Man. Even as a *Homo erectus* bone, it was noticeably different from other specimens. Dubois deduced – correctly, as it turned out – that ape-men walked upright. From a mere skullcap and a tooth, Dubois even reconstructed an entire skull model that later proved remarkably accurate.
Dubois returned to Europe in 1895, expecting a hero's welcome. He received almost the opposite. Most scientists rejected his conclusions and disliked his arrogant manner. They declared the skullcap to be that of an ape, most likely a gibbon, and certainly not an early human. In 1897, hoping to bolster his claims, Dubois commissioned a reconstruction of the skullcap from Gustav Schwalbe, a respected anatomist at the University of Strasbourg. Schwalbe’s resulting paper drew far more attention and support than anything Dubois himself had written, much to Dubois' chagrin. Schwalbe subsequently embarked on a series of well-received lectures, as if he had unearthed the fossil himself. Bitter and disillusioned, Dubois retreated into obscurity, accepting a professorship in geology at the University of Amsterdam. For the next two decades, he forbade anyone from examining his prized fossils, dying in 1940, a man consumed by resentment.
Meanwhile, on the other side of the world, Raymond Dart, an Australian-born professor of anatomy at the University of Witwatersrand in Johannesburg, South Africa, received a remarkably complete skull of a juvenile, complete with face, jaw and endocast – a natural brain cast – from a limestone quarry at a place called Taung, on the edge of the Kalahari Desert in 1924. Dart immediately recognized that it was not a *Homo erectus* like Dubois' Java Man, but something more primitive, more apelike. He estimated its age at around two million years and named it *Australopithecus africanus,* or "Southern Ape of Africa." In his report, published in *Nature*, Dart called the Taung child strikingly similar to humans, and proposed that his discovery needed an entirely new family: the Hominidae (the "Human-apes").
Dart fared even worse than Dubois in the halls of academia. Virtually everything about Dart’s theory – indeed, it seemed, about Dart himself – displeased the establishment. He was perceived as arrogant for undertaking the analysis himself, rather than seeking the counsel of more seasoned experts. Even his choice of name, *Australopithecus* – a hybrid of Greek and Latin roots – betrayed a perceived lack of scholarly rigor. Worst of all, his theory flew in the face of conventional wisdom. The prevailing view held that humans and apes had diverged in Asia at least fifteen million years prior. If humans had emerged from Africa, heavens forbid, might we be related to Negroes? It was akin to someone today claiming to have found the fossil remains of human ancestors in, say, Missouri. It simply didn’t fit the accepted narrative.
Dart’s sole prominent champion was Robert Broom, a Scottish-born physician, physicist and paleontologist of considerable brilliance but also considerable eccentricity. Broom, for example, was known to conduct field work in the nude when the weather was warm, which it often was. He was also rumored to have performed questionable dissections on impoverished patients who died – frequently, it seemed – and then bury the bodies in his garden for later study.
Broom was a skilled paleontologist, and because he resided in South Africa, he was able to examine the Taung skull firsthand. He immediately recognized its significance, and defended Dart tirelessly, to no avail. For the next fifty years, the prevailing opinion remained that the Taung Child was merely an ape, nothing more. Most textbooks omitted it altogether. Dart spent five years writing a monograph, only to find no one willing to publish it, at which point he stopped trying (though he continued fossil hunting). The skull – now considered one of anthropology's most prized treasures – was used as a paperweight on a colleague’s desk for many years.
In 1924, when Dart announced his discovery, only four kinds of ancient humans were known: Heidelberg Man, Rhodesian Man, Neanderthals, and Dubois’ Java Man – but all of this was about to change dramatically.
In China, a Canadian amateur archaeologist named Davidson Black began excavations at a site known as Dragon Bone Hill. The hill was known locally for its ancient fossils, which, tragically, weren’t being collected for scientific study but ground up into powder for use in traditional medicine. We don’t know how many invaluable *Homo erectus* fossils were consumed by locals for their medicinal properties. By the time Black arrived, the site had been extensively ravaged, but he still managed to discover a single molar. From that, he deduced the existence of a new type of hominid: *Sinanthropus pekinensis,* or "Peking Man."
Spurred on by Black’s findings, more vigorous excavations were undertaken, yielding numerous other fossils. Sadly, these were all lost in 1941, on the day after the attack on Pearl Harbor. As a group of American Marines attempted to evacuate the fossils from China, they were intercepted by Japanese soldiers and taken prisoner. The Japanese examined their crates, found nothing but bones, and discarded them by the roadside. They have never been seen since.
Meanwhile, back in the same area where Dubois had discovered Java Man, an expedition led by Ralph von Koenigswald uncovered another collection of early human fossils along the Solo River, in the Ngandong region. These were later named "Solo Man" after their discovery location. Koenigswald’s find would have been more spectacular had he not made a strategic blunder, or perhaps too late. He had promised the locals ten cents for every human fossil they found. To his dismay, he discovered that they were smashing larger fossils into smaller pieces in order to maximize their earnings.
Over the ensuing years, as more and more fossils were discovered and identified, a flurry of new names emerged: Aurignacian, *Australopithecus transvaalensis,* *Paranthropus robustus,* *Zinjanthropus boisei,* and dozens of others, each seemingly warranting a new genus or species. By the 1950s, the number of named hominid species had surpassed one hundred. Adding to the confusion, many names were subsequently subjected to further revision, refinement, and argument by paleoanthropologists. Solo Man, for instance, was variously classified as *Homo soloensis,* *Javanthropus,* *Homo neanderthalensis soloensis,* *Homo sapiens soloensis,* *Homo erectus soloensis,* before finally being simplified to *Homo erectus.*
In 1960, in an attempt to bring order to the chaos of hominid taxonomy, Clark Howell of the University of Chicago, following the recommendations of Ernst Mayr and others in the preceding decade, proposed a reduction to just two genera – *Australopithecus* and *Homo* – and streamlined many of the species classifications. Java Man and Peking Man both became *Homo erectus.* This classification held sway for a while, but didn’t last.(Humans belong to the subfamily Homininae, whose members are traditionally called hominids and include any creature [extinct or otherwise] more closely related to us than to chimpanzees. Apes and hominids together form the superfamily Hominoidea. Many authorities now feel that chimpanzees, gorillas, and orangutans should also be included in this group, and that humans and chimps belong in the same subfamily, called Hominini. According to this system, all traditional hominids become hominoids. [Leakey and others have been holding out.] Hominoidea is then used as the general term for apes, including us.)
After a decade or so of relative calm, paleoanthropology entered a period of accelerated discovery that continues to this day. *Homo habilis,* discovered in the 1960s, was seen by some as filling the gap between apes and humans, but by others as not a separate species at all. Then came (among many others) *Homo ergaster,* *Kenyanthropus platyops,* *Homo rudolfensis,* *Homo antecessor,* *Australopithecus afarensis,* *Australopithecus walkeri,* *Australopithecus anamensis,* *Australopithecus garhi,* and so on. There are now, by some counts, nearly twenty documented species of hominid, though no two experts can agree on which twenty.
Some experts continue to work within Howell’s two-genus framework of 1960, while others elevate certain australopithecines to their own genus, *Paranthropus*, and still others add an even earlier genus, *Ardipithecus*. Some place *praegens* in *Australopithecus*, others in a new genus, *Praehomo.* Most don't accept *praegens* as a distinct species at all. With no widely-regarded authority to reconcile these differing viewpoints, the only way a name becomes accepted is when no one objects to it, which is often difficult to achieve.
To a large extent, however, the problem lies in the paucity of evidence. It's paradoxical. Billions of humans (or proto-humans) have lived since the dawn of humankind, each passing on a slightly different genetic code to all of humanity. Yet, out of this vast population, our knowledge of prehistory rests on the fragmentary remains of only about 5,000 individuals. As Ian Tattersall, a curator at the American Museum of Natural History in New York, told me, "If you weren’t too worried about making a mess, you could pile all the hominid and early human fossils found to date on the back of a pick-up truck."
Even this scarcity wouldn't be so bad if the fossils were evenly distributed through time and space. Of course, they are not. They occur sporadically, creating tantalizing but often unbridgeable gaps. *Homo erectus* existed on Earth for over a million years, inhabiting a range stretching from the Atlantic coast of Europe to the Pacific coast of China, yet if you could resurrect every *Homo erectus* fossil found, they wouldn’t fill a school bus. *Homo habilis* is even more poorly represented: two incomplete skeletons and a handful of isolated limb bones. Some events that lasted as short as our civilization will most certainly never be proven based on the fossil record.
To illustrate, Tattersall explained: “In Europe, you have a hominid skull in Georgia from 1.7 million years ago, then a fossil in Spain, at the other end of the continent, that’s almost a million years younger, then a Heidelberg Man in Germany 300,000 years after that. There's hardly anything in common among them.” He paused with a wry smile. “And that’s what you’re trying to use to generalize about the history of humanity. It’s tough. We really don't know much about the relationships among many ancient species, which ultimately evolved into humans, which went extinct along the way. Some perhaps should not be separate species at all.”
This incompleteness in the record makes each new discovery seem sudden and distinct, radically different from all the others. If millions of fossils were evenly spaced across time, their subtle differences would be clear. As it is, new species seem to spring into being fully formed. The closer you get to any dividing line, the more blurred the distinctions become. Distinguishing a late *Homo sapiens* from an early *Homo erectus*, for example, can be difficult, even impossible, because they are so similar. Similar problems arise when classifying fragmentary remains – deciding whether a particular bone belongs to a female *Australopithecus boisei* or a male *Homo habilis* is a daunting task.
The study of hominid fossils is so fraught with uncertainty that scientists are often forced to make assumptions based on circumstantial evidence found nearby – assumptions that can be little more than educated guesses. As Alan Walker and Pat Shipman observed wryly, if one were to rely on the tools frequently found near fossilized bones, one would be forced to conclude that early stone tools were largely the handiwork of antelope.
Perhaps the most confusing aspect of the fragmentary *Homo habilis* record is the apparent contradictions it presents. In isolation, *Homo habilis* fossils are unrevealing. Placed together, however, they suggest that males and females were evolving at different rates and in different directions. Over time, the males became increasingly distinct from apes, exhibiting more human characteristics, while the females, during the same period, seemed to be evolving toward more apelike traits. Some authorities believe there is no valid reason to classify *Homo habilis* as a separate species at all. Tattersall and his colleague, Jeffrey Schwartz, consider it to be nothing more than a "wastebasket species" – one into which unrelated fossils can be conveniently "tossed." Even those who accept *Homo habilis* as distinct cannot agree whether it belongs within our own genus or a separate, now-extinct, branch.
Finally, and perhaps most importantly, there is the human factor. Scientists are, understandably, inclined to interpret their discoveries in a way that best enhances their reputations. Few paleontologists, upon unearthing a set of bones, are likely to announce that their find is unremarkable. As John Reader observed succinctly in his book, *Missing Links*, "It is always interesting to note how the discoverer's initial interpretation of new evidence tends to confirm whatever he thought beforehand."
All of this inevitably leaves plenty of room for argument, and few relish an argument more than paleoanthropologists. "Of all scientists, paleoanthropologists are perhaps the most prone to inflate their own egos," observe the authors of the recent book, *Java Man.* A notable feature of that book is the extensive and unabashed criticism of others, especially of former friend and colleague Donald Johanson. Here's a taste:
"During our time at the institute, he [Johanson] unfortunately developed a habit of moodiness, loud harangues, sometimes accompanied by violent gestures like flinging books or whatever else was at hand."
So, let us bear firmly in mind that, when it comes to the history of prehistoric humans, there is very little that isn't disputed by someone, somewhere. What we can be most certain about, concerning who we think we are, and where we believe we come from, is as follows:
As organisms, we shared 99.99999 percent of our history with the chimpanzees of Africa. We know virtually nothing of prehistoric African chimpanzees, but whatever their circumstances, our ancestors were much like them. Then, about seven million years ago, something decisive happened. A new group of animals emerged from the African rainforests and began to venture into the open savanna.
Enter the Australopithecines. For the next five million years, they were the dominant hominids on Earth. (Austral is Latin for "southern," and has nothing to do with Australia.) Australopithecines evolved into several distinct branches, some gracile, like the Taung Child discovered by Raymond Dart, others more robust, but all were capable of walking upright. Some of these species survived for over a million years, others for only a few hundred thousand. But it should be made clear, even the shortest lived species history would be greater by multiples than our own.
The most famous Australopithecine remains are those of a 3.18-million-year-old skeleton discovered in 1974 in Hadar, Ethiopia, by a team led by Donald Johanson. Designated A.L. (for Afar Locality) 288-1, it later became affectionately known as "Lucy," after the Beatles song, "Lucy in the Sky with Diamonds." Johanson never doubted her significance. “It was our earliest ancestor. The missing link between apes and men.”
Lucy was small, barely three feet tall, and she walked upright, though whether she did so well remains open to debate. She was clearly an adept climber. Other aspects of her are less certain. Her skull is almost entirely absent, making it difficult to ascertain her brain size with any confidence, though the remaining skull fragments suggest that it was not large. Many books refer to Lucy’s skeleton as being 40 percent complete, others say nearly 50 percent, a book from the American Museum of Natural History said that two thirds were complete, and narration for a BBC Television series *Ape Man* said "a complete skeleton," but the footage shown was not the case.
A human has 206 bones, but many are duplicated. If you have a left femur, you know the size of its missing right femur. When you remove all the duplicates, you have a total of 120 distinct bones - a "hemi-skeleton." Even by that measure, counting even the smallest shard as a complete bone, only 28 percent of Lucy’s hemi-skeleton was recovered (about 20 percent of a complete skeleton).
In his book *Wisdom of the Bones*, Alan Walker recalls asking Johanson how he arrived at the 40 percent figure. Johanson, smiling, confessed that he didn't include the 106 bones of the hands and feet – even though the bones of the hands and feet make up over half of the entire human skeleton, and are an important half because they are how Lucy dealt with an everchanging world. In fact, we know much less about Lucy than we presume. We don't even know that she was female, her sex is only extrapolated by her small stature.
Two years after the discovery of Lucy, at Laetoli in Tanzania, Mary Leakey discovered what are believed to be a string of footprints left by two hominids of the same family. The impressions were made as the two Austrolopithecines walked through volcanic ash after an eruption. The ashes then hardened, and the two kept walking, leaving footprints for over 23 meters.
The American Museum of Natural History in New York has an exhibit displaying a facsimile showing the hominids as they passed by. In a diorama, two hominids, a male and female, shoulder-to-shoulder, cross an ancient African plain; they are hairy, of a similar size to chimpanzees, but their facial expressions and walking posture denote that they are human. The most touching sight of the diorama is the male, with his left arm across the shoulders of the female, protecting her, a gesture that reveals the inter-personal relationship that they have.
It is an emotive scene, so much so that one might easily overlook the fact that virtually everything depicted about these footprints is conjecture. Almost all their external features – the length of their hair, the shape of their facial features (were their noses more human or more gorilla?), their expressions, their skin tone, the size and shape of the woman’s breasts – are pure fabrication. We can’t even be certain that they were a couple. The female may have been a juvenile. We can’t even be sure that they were Australopithecines. They are only assumed to be Australopithecines because we know of no other candidates.
I had been told that their posture was due to the fact that the female was toppling over throughout the installation. However, Ian Tattersall insisted, smiling, that wasn’t the case. “Obviously we have no idea if the man had his arm across the woman’s shoulders, but from measuring their strides, we can tell that they were walking shoulder to shoulder. They were very close together – close enough to touch. It was an open area, so they were probably feeling vulnerable, which is why we’ve given them slightly apprehensive expressions.”
I had asked Tattersall if there were many problems like these when crafting the diorama. He said "It's often problematic when you're recreating. You might not believe how many arguments are started over whether or not Neaderthals had eyebrows. The same is true for the statue in Laetoli. We really don't know what they looked like, but we can ascertain the height, the stance, and make a deduction based on what they may have looked like. If I were to recreate the exhibit, I would make them look a little bit more ape like. They were not human, they were bipedal apes."
Until quite recently, it was believed that we were descendants of Lucy and the creatures from Laetoli, but many authorities today are less certain. While some characteristics (such as their teeth) suggest a link between Australopithecines and us, other aspects of Australopithecine anatomy tell a different story. The upper half of a human femur is quite similar to an ape, and not to those of Austrolopithecines, Tattersall and Schwartz point out in *Extinct Humans*. So if Lucy is a direct ancestor of humans, it means for about a million years we had the same femur as austrolopithecines, before at the next stage of our development, we went back to one more akin to that of an ape. Instead, they believe that Lucy was not only not our ancestor, it is possible that she was not bipedal.
"Lucy and her kin did not walk in the way that modern humans walk" Tattersall stated. "They only walked upright while travelling between the two habitats that they rested in, both of which were trees. Due to the structure of their bone structures, they were forced to walk upright." Johanson disagreed, writing "Because of the contours of Lucy's hips, and how her pelvic muscles grew, it would have been as hard for her to climb trees as it is for a modern human."
Things became muddier with the discovery of four peculiar new fossils in 2001 and 2002. One, discovered near Lake Turkana in Kenya by Meave Leakey (whose family is famous for fossil hunting), was dubbed *Kenyanthropus platyops,* or "Flat-Faced Man of Kenya." Dating from roughly the same period as Lucy, its existence raises the possibility that it, not Lucy, was our ancestor, and that Lucy belongs to a now-extinct branch. 2001 also saw the discovery of two other species, *Ardipithecus ramidus kadabba,* dating from between 5.8 and 5.2 million years ago, and *Orrorin tugenensis,* dating possibly from 6 million years. The later was the oldest hominid to have been discovered - though this record only lasted for a short amount of time. In the summer of 2002, a French team working in the Djurab Desert of Chad (an area where no ancient fossils had been discovered) unearthed a 7-million-year-old hominid, which they named *Sahelanthropus tchadensis* (some believe that this is not human, rather an early hominid, that should be called *Sahelpithecus*). All these creatures are very old, very primitive, and yet all were capable of walking upright. They had been doing so for far longer than anyone imagined.
Bipedalism was a skillful and risky alteration. It meant changing the pelvis structure to support the entire weight of the body. In order to retain the necessary support, the birth passage of the female must become relatively narrow. This change caused three things to happen; two instantly, and one down the line. First, this meant that childbirth became a more painful, with a greater risk of death for the mother and child. Second, for babies to pass through the narrow passage, their brains had to be developed when they were still small - therefore, new babies would need to be dependent on parental care. This meant the relationship between the male and female had to be very strong.
Even today, when you’ve become the most intellectually advanced person on the planet, it is still a big problem. For the small and defenseless Autrolopithecines, a baby born with a brain the size of a mandarin, (Admittedly, sheer brain size doesn't tell the whole story – and sometimes tells very little. Elephants and whales have much larger brains than we do, but they are not smarter than you. Brain size is only a relatively important data point that can often be ignored. As Gould pointed out, the average *Australopithecus africanus* had a brain capacity of only 450 cubic centimeters, less than that of a gorilla. However, an average *Australopithecus africanus* would have weighed less than 45kg, a female even less, while most gorillas have a body mass of 150kg.) the risks would be great.
So, why did Lucy and her kin abandon the trees and venture out of the African rainforests? In all likelihood, they had little choice. The gradual uplift of the Isthmus of Panama, blocking the flow of Pacific waters into the Atlantic, altered the course of warm currents flowing toward the Arctic, triggering a period of exceptional cooling and glaciation in northern latitudes. In Africa, the emergence of seasonal dryness and cooler conditions gradually transformed forests into grasslands. “It was not so much that Lucy and her kin left the forest,” writes John Gribbin, “as that the forest left them.”
But by venturing into open grasslands, the early hominids exposed themselves. Hominids on two feet could see farther, but were also easier to see. Even now, as a species, we are almost ridiculously defenseless in the wild. Virtually all the large animals we can name are stronger, faster, and possess sharper teeth. Faced with an attack, modern humans have just two advantages. We possess relatively large brains, capable of devising solutions, and we have dexterous hands, capable of throwing or wielding lethal objects. We are the only animal capable of killing at a distance, and therefore one which does not fear attack.
All factors would appear to favor rapid brain evolution, but this doesn’t seem to have happened. For over three million years, Lucy and her Australopithecine comrades remained much the same. Their brain size did not increase, nor is there any evidence that they used even the simplest of tools. Oddly, we now know that other early hominids, who lived alongside them for nearly a million years, did use tools, yet the Australopithecines never availed themselves of this useful technology.
Sometime between three and two million years ago, as many as six hominid groups are estimated to have coexisted on the African continent. Only one, however, was destined to endure: *Homo*. They emerged around two million years ago. No one fully understands the relationship between the Australopithecines and *Homo*, only that they coexisted for roughly a million years. Then, about one million years ago, all the Australopithecines, both robust and gracile, vanished mysteriously, or perhaps suddenly. No one knows why. “Perhaps,” suggests Matt Ridley, “we ate them.”
*Homo* is generally believed to have begun with *Homo habilis*, a species about which we know very little, and to have culminated in us, *Homo sapiens* (literally, "wise man"). In between there have been as many as six other *Homo* species depending on what opinion you have: *Homo ergaster,* *Homo neanderthalensis,* *Homo rudolfensis,* *Homo heidelbergensis,* *Homo erectus,* and *Homo antecessor*.
*Homo habilis* (“handy man”) was named by Louis Leakey and his colleagues in 1964. The name was chosen because they were the first hominids known to use tools – albeit very simple ones. They were fairly primitive, more apelike than human, but with a brain capacity roughly 50 percent larger than that of Lucy – not a small margin, and certainly the Einsteins of their time. There is no reason to conclusively state why the brains of hominids began growing all of a sudden two million years ago. For a long time, it was thought that brain development was directly related to bipedalism - that hominids who ventured from the forests had to make more complex plans that furthered the evolution of the brain - and so it was a bit shocking to repeatedly discover so many dumb bipedal animals, making everyone realized there was no obvious correlation between the two.
"There is simply no overwhelming evidence to explain why the brains of humans began increasing" Tattersall said. Giant brains are high-energy organs. They account for only 2 percent of the body's mass, but consume 20 percent of our energy. They are also particular about what they use for energy. Your brain won't complain if you never eat fatty foods, as it isn't interested. However, it does like glucose, and it wants a lot of it, even at the expense of other organs. As Guy Brown put it: “The gluttonous brain is often in danger of starving the body, but it dares not starve itself, because that would quickly lead to death.” The bigger your brain, the more you have to eat, the more you eat, the greater the risk.
Tattersall believes that brain enlargement may have simply been a evolutionary accident. He believes Stephan Jay Gould’s claim that, were you to replay the process of life, even if you started it from the point of time that hominids appeared, the chances that humans, or anything resembling them, would evolve to this point are "utterly negligible."
“One of the hardest things for people to accept,” he says, “is that we are not the culmination of anything. We are here, but it didn’t have to be this way. Partly through human conceit, we tend to view evolution as a process somehow designed to produce us. Even anthropologists did this until the 1970s. Indeed, even as late as 1991, in a widely used textbook called *Stages of Human Evolution*, C. Loring Brace was still rigidly adhering to such a linear view of evolution. He admitted only one evolutionary dead end, the extinction of *Australopithecus robustus*. All the other species represented a straight line of evolution, each species passing the baton to a younger successor. As it is, it now seems clear that many of these early species went down side roads, and became extinct."
We are fortunate that one branch was successful - a group of tool making hominids appeared abruptly, co-existing with the elusive and contested *Homo habilis*: *Homo erectus*, the Java Man found by Eugene Dubois in 1891. It existed from as far back as 1.8 million years ago, to as recently as 200,000 years ago, depending on who you ask.
According to the authors of *Java Man*, *Homo erectus* is a dividing line. Everything before had more features of an ape, everything after, those of a human. *Homo erectus* was the first to hunt, the first to use fire, the first to make complex tools, the first to leave evidence of campsites, the first to care for the weak. More than any previous species, *Homo erectus* looked and behaved like a human, with longer limbs, a leaner body, and enough energy and intellect to successfully colonize a vast range of territory. To other hominids, *Homo erectus* must have seemed large, powerful, agile and capable. Their brains were the most advanced that the world had ever seen.
According to Alan Walker, one of the world's most respected scholars from the Pennsylvania State University, *Homo erectus* was "the velociraptor of his day." If you were to look directly at him, *Homo erectus* could appear like a human, but "you would not want to negotiate with him, you would become his food." According to Walker, they had the bodies of an adult and the brains of a baby.
While *Homo erectus* was discovered nearly a century ago, we were only able to piece together tidbits of fossilized bones- not even a complete skeleton could be made. It wasn't until the 1980's, with the extraordinary discovery in Africa, that the importance, or at least the possible importance, was fully recognized. The remote Lake Turkana region (previously Lake Rudolph) in Kenya is now one of the most fruitful areas in the world for early human fossils, but for a long time, no one thought to look there: it was only after a plane deviated from its course to fly over the area that Richard Leaky realized it might be more promising than previously thought. An expedition was sent to the area, and initially they found nothing. One afternoon, late in the day, Kamoya Kimeu, Leaky’s most renowned fossil hunter, was a short distance from the lake in the mountains when he discovered a small fragment of a hominid brow ridge. He was in a location that was not likely to yield much, but out of respect for Kimeu's instincts, everyone began digging. Shockingly, a near perfect *Homo erectus* skeleton was unearthed. It was of a boy, aged 9-12, who had died 1.54 million years ago. Tattersall stated that the skeleton had "all the body structures of modern humans." In some ways, it was a discovery without equal. "Turkana Boy was clearly one of us."
Kimeu also discovered a 1.7 million year old female skeleton near Lake Turkana, named KNM-ER1800. It was the first time that scientists had a clue, that the *Homo erectus* were more interesting and intricate than previously thought. The female had malformed bones, covered in spots, that showed that she had been suffering from chronic condition called hypervitaminosis A, which is only caused by eating the liver of carnivorous animals. It was the first time we learned that the *Homo erectus* were carnivorous. Even more shockingly, the amount of spots on her bones showed that she had been sick for weeks, maybe months, before passing away. She had been taken care of. It was one of the first signs of compassion found in human evolution.