Adding to these images of hominid activity 1.5 million years ago is a message from the stones themselves. When a stone-knapper strikes flakes from a cobble, the pieces tend to fall in a small area around him or her. This is just what the University of Wisconsin archeologist Ellen Kroll found at site 50: stone-knapping was concentrated at one end of the site. Similarly, the bone pieces—there were parts of giraffe, hippopotamus, an eland-size antelope, and a zebra-like animal, as well as catfish spines—were concentrated in the same place. “We can only speculate what made the northern end of the site a favorite place to do things, but the observed pattern could, for example, imply the existence of a shady tree there,” Isaac and his colleagues wrote. An even more remarkable aspect of the stone flakes was that, like the shattered long bone, some of these too could be reconstructed to form the original whole, a lava cobble.
FIGURE 4.1
Signs of ancient butchery. These small cut marks (indicated by arrows) in the surface of a fossilized animal bone from a 1.5-million-year-old archeological site in northern Kenya show that early humans used sharp stone implements to remove flesh from animal carcasses. (Courtesy of R. Lewin.)
I mentioned in chapter 2 that Nicholas Toth and Lawrence Keeley had performed microscopic analysis of several stone flakes and found indications of butchery, wood whittling, and the cutting of soft plant tissue. Those flakes were from site 50, and the results of the analysis add to the image of a scene of diverse activity 1.5 million years ago. Far from the hydraulic jumble image, the activity at site 50 must have involved hominids bring parts of carcasses there, which were then processed with stone tools made at the site. The demonstration of the deliberate transport of bones and stones to a central place of food-processing activity was a major step in realigning archeological theory, after the theoretical turmoil of the late 1970s. But does this evidence imply that the hominids of site 50, Homo erectus, were hunters or scavengers?
Isaac and his colleagues put it this way: “The characteristics of the bone assemblage invite serious consideration of scavenging rather than active hunting as a prominent mode of meat acquisition.” Had entire carcasses been found at the site, a conclusion of hunting could be drawn. But, as I indicated earlier, the interpretation of patterns of bone assemblages is fraught with potential error. Other lines of evidence, however, have been adduced to imply scavenging as the mode of meat acquisition in early Homo. For instance, Shipman examined the distribution of cut marks on ancient bones and made two observations. First, only about half were indicative of dismemberment; second, many were on bones that bore little meat. Furthermore, a high proportion of cut marks crossed over marks left by carnivore teeth, implying the carnivores got to the bones before the hominids did. This, Shipman concluded, is “compelling evidence for scavenging,” an image of our ancestor she notes is “unfamiliar and unflattering.” It is certainly far from the Man the Noble Hunter image of traditional theory.
I would expect that the meat quest in early Homo would have involved scavenging. As Shipman observed, “Carnivores scavenge when they can and hunt when they must.” But I suspect that the recent intellectual revolution in archeology has gone too far, as often happens in science. The rejection of hunting in early Homo has been too assiduous. I find it significant that Shipman’s analysis of the distribution of cut marks shows so many on bones with little meat. What can be obtained here? Tendons and skin. With these materials it is very easy to make effective snares for catching quite large prey. I would be very surprised if early Homo erectus did not engage in this form of hunting. The humanlike physique that emerged with the evolution of the genus Homo is consistent with a hunting adaptation.
For Isaac the work at site 50 was salutary. Although it confirmed that hominids were transporting bone and stone to a central place, it did not necessarily demonstrate that the hominids used that location as a home base. “I now recognize that the hypotheses about early hominid behavior I have advanced in previous papers made the early hominids seem too human,” he wrote in 1983. He therefore suggested modifying his “food-sharing hypothesis,” making it the “central-place-foraging” hypothesis. I suspect he was being too cautious.
I cannot say that the results of the project at site 50 confirm the hypothesis that Homo erectus lived as hunter-gatherers, moving every few days from one temporary home base to another—bases to which they brought food and where they shared it. How much of the social and economic milieu of Isaac’s original food-sharing hypothesis might have been present at site 50 remains elusive. But in my judgment there is sufficient evidence from the work to dispense with the notion that early Homo was little advanced beyond the chimpanzee grade of social, cognitive, and technological competence. I’m not suggesting that these creatures were hunter-gatherers in miniature, but I’m sure that the humanlike grade of the primitive hunter-gatherer was beginning to be established at this time.
Although we can never know for certain what daily life was like in the earliest times of Homo erectus, we can use the rich archeological evidence of site 50, and our imagination, to re-create such a scene, 1.5 million years ago:
A seasonal stream courses its way gently across a broad floodplain on the east side of a giant lake. Tall acacia trees line the stream’s circuitous banks, casting welcome shade from the tropical sun. For much of the year the stream bed is dry, but recent rains in the hills to the north are working their way down to the lake, slowly swelling the stream. For a few weeks now, the floodplain itself has been ablaze with color, with flowering herbs splashing pools of yellow and purple against the orange earth and low acacia bushes looking like billowing white clouds. The rainy season is imminent.
Here, in a curve in the stream, we see a small human group, five adult females and a cluster of infants and youths. They are athletic in stature, and strong. They are chattering loudly, some of their exchanges obvious social repartee, some the discussion of today’s plans. Earlier, before sunrise, four adult males of the group had departed on a quest for meat. The females’ role is to gather plant foods, which everyone understands are the economic staple of their lives. The males hunt, the females gather: it’s a system that works spectacularly well for our group and for as long as anyone can remember.
Three of the females are now ready to leave, naked apart from an animal skin thrown around the shoulders that serves the dual role of baby carrier and, later, food bag. They carry short, sharp sticks, which one of the females had prepared earlier, using sharp stone flakes to whittle stout twigs. These are digging sticks, which allow the females to unearth deeply buried, succulent tubers, foods denied to most other large primates. The females finally set off, walking along single file as they usually do, toward the distant hills of the lake basin, following a path they know will take them to a rich source of nuts and tubers. For ripe fruit, they will have to wait until later in the year, when the rains have done nature’s work.
Back by the stream, the remaining two females rest quietly on the soft sand under a tall acacia, watching over the antics three youngsters. Too old to be carried in an animal-skin baby carrier, too young either to hunt or to gather, the youngsters do what all human youngsters do: they play games of pretending, games that foreshadow their adult lives. This morning, one of them is an antelope, using branches for antlers, and the other two are hunters stalking their prey. Later, the eldest of the three, a girl, persuades one of the females to show her, again, how to make stone tools. Patiently, the woman brings two lava cobbles together with a swift, sharp blow. A perfect flake flies off. With studied determination, the girl tries to do the same, but without success. The woman takes hold of the girl’s hands and guides them through the required action, in slow motion.
Making sharp flakes is harder than it looks, and the skill is taught mainly through demonstration, not verbal instruction. The girl tries again, her action subtly different this time. A sharp flake arcs off the cobble, and the girl lets out of yelp of triumph. She snatches up the flake, shows it to the smiling woman, and then runs to
display it to her playmates. They pursue their games together, now armed with an implement of adulthood. They find a stick, which the apprentice stone-knapper whittles to a sharp point, and they form a hunting group, in search of catfish to spear.
By dusk, the stream-side campsite is bustling again, the three woman having returned with their animal skins bulging with babies and food, including some birds’ eggs, three small lizards, and—an unexpected treat—honey. Pleased with their own efforts, the women speculate on what the men will bring. On many days, the hunters return empty-handed. This is the nature of the meat quest. But when chance favors their efforts, the reward can be great, and it is certainly prized.
Soon, the distant sound of approaching voices tells the women that the men are returning. And, to judge from the timbre of excitement in the men’s conversation, they are returning successful. For much of the day the men have been silently stalking a small herd of antelope, noting that one of the animals seemed slightly lame. Repeatedly, this individual was left behind by the herd and had to make tremendous efforts to rejoin them. The men recognized the chance to bring down a large animal. Hunters who are equipped with the minimum of natural or artificial weaponry, as our group is, need to rely on cunning. The ability to move quietly and to blend into the environment and the knowledge of when to strike are these hunters’ most potent weapons.
Finally, an opportunity presented itself and, with unspoken agreement, the three men moved into strategic positions. One of them let loose a rock with precision and force, striking a stunning blow; the other two ran to immobilize the prey. A swift stab with a short, pointed stick released a fountain of blood from the animal’s jugular. The animal struggled but was soon dead.
Tired and covered in the sweat and blood of their efforts, the three men were exultant. A nearby cache of lava cobbles provided raw material for making tools that would be necessary for butchering the beast. A few sharp blows of one cobble against another produced sufficient flakes with which to slice through the animal’s tough hide and begin exposing joints, red flesh against white bone. Swiftly, muscles and tendons yielded to skillful butchering, and the men set off for camp, carrying two haunches of meat and laughing and teasing each other over the events of the day and their different roles in them. They know a gleeful reception will greet them.
There’s almost a sense of ritual in the consumption of the meat, later that evening. The man who led the hunting group slices off pieces and hands them to the women sitting around him and to the other men. The women give portions to their children, who exchange morsels playfully. The men offer pieces to their mates, who offer pieces in return. The eating of meat is more than sustenance; it is a social bonding activity.
The exhilaration of the hunting triumph now subsided, the men and women exchange leisurely accounts of their separate days. There’s a realization that they will soon have to leave this congenial camp, because the growing rains in the distant hills will soon swell the stream beyond its banks. For now, they are content.
Three days later the group leaves the camp for the last time to seek the safety of higher ground. Evidence of their evanescent presence is scattered everywhere. Clusters of flaked lava cobbles, whittled sticks, and worked hide speak of their technological prowess. Broken animal bones, a catfish head, eggshells, and remnants of tubers speak of the breadth of their diet. Gone, however, is the intense sociality that is the camp’s focus. Gone, too, are the ritual of meat eating and the stories of daily events. Soon, the empty, quiet camp is flooded gently, as the stream gently laps over its bank. Fine silt covers the litter of five days in the life of our small group, entrapping a brief story. Eventually all but bone and stone decay, leaving the most meager of evidence from which to reconstruct that story.
Many will believe that my reconstruction makes Homo erectus too human. I do not think so. I create a picture of a hunter-gatherer lifestyle, and I impute language to these people. Both, I believe, are justifiable, although each must have been a primitive version of what we know in modern humans. In any case, it is very clear from the archeological evidence that these creatures were living lives beyond the reach of other large primates, not least in using technology to gain access to foods such as meat and underground tubers. By this stage in our prehistory, our ancestors were becoming human in a way we would instantly recognize.
CHAPTER 5
THE ORIGIN OF MODERN HUMANS
Of the four major events in the course of human evolution which I outlined in the preface—the origin of the human family itself, some 7 million years ago; the subsequent “adaptive radiation” of species of bipedal apes; the origin of the enlarged brain (effectively, the beginning of the genus Homo), perhaps 2.5 million years ago; and the origin of modern humans—it is the fourth, the origin of people like us, that is currently the hottest issue in anthropology. Very different hypotheses are vigorously debated, and hardly a month passes without a conference being held or a shower of books and scientific papers being published, each of these putting forward views that are often diametrically opposed. By “people like us” I mean modern Homo sapiens—that is, humans with a flair for technology and innovation, a capacity for artistic expression, an introspective consciousness, and a sense of morality.
As we look back into history just a few thousand years, we see the initial emergence of civilization: in social organization of greater and greater complexity, villages give way to chiefdoms, chiefdoms give way to city-states, city-states give way to nation-states. This seemingly inexorable rise in the level of complexity is driven by cultural evolution, not by biological change. Just as people a century ago were like us biologically but occupied a world without electronic technology, so the villagers of 7000 years ago were just like us but lacking in the infrastructure of civilization.
If we look back into history beyond the origin of writing, some 6000 years ago, we can still see evidence of the modern human mind at work. Beginning about 10,000 years ago, nomadic bands of hunter-gatherers throughout the world independently invented various agricultural techniques. This, too, was the consequence of cultural or technological, not biological, evolution. Go back beyond that time of social and economic transformation and you find the paintings, engravings, and carvings of Ice Age Europe and of Africa, which evoke the mental worlds of people like us. Go back beyond this, however—beyond about 35,000 years ago—and these beacons of the modern human mind gutter out. No longer can we see in the arche-ological record cogent evidence of the work of people with mental capacities like our own.
For a long time, anthropologists believed that the sudden appearance of artistic expression and finely crafted technology in the archeological record some 35,000 years ago was a clear signal of the evolution of modern humans. The British anthropologist Kenneth Oakley was among the first to suggest, in 1951, that this efflorescence of modern human behavior was associated with the first appearance of fully modern language. Indeed, it seems inconceivable that a species of human could possess fully modern language and not be fully modern in all other ways, too. For this reason, the evolution of language is widely judged to be the culminating event in the emergence of humanity as we know it to be today.
When did the origin of modern humans occur? And in what manner did it happen: gradually and beginning a long time ago, or rapidly and recently? These questions are at the core of the current debate.
Ironically, of all the periods of human evolution, that of the past several hundred thousand years is by far the most richly endowed with fossil evidence. In addition to an extensive collection of intact crania and postcranial bones, some twenty relatively complete skeletons have been recovered. To someone like me, whose preoccupation is with an earlier period in human prehistory, in which fossil evidence is sparse, these are paleontological riches in the extreme. And yet a consensus on the sequence of evolutionary events still eludes my anthropological colleagues.
Moreover, the very first early human fossils ever discovered were of Neanderthals (everyone’s favorite car
icature of cavemen), who play an important role in the debate. Since 1856, when the first Neanderthal bones were uncovered, the fate of these people has been endlessly discussed: Were they our immediate ancestors or an evolutionary dead end that slipped into extinction some thirty millennia before the present? This question was posed almost a century and a half ago, and is still unanswered, at least to everyone’s satisfaction.
Before we delve into some of the finer points of the argument over the origin of modern humans, we should outline the larger issues. The story begins with the evolution of the genus Homo, prior to 2 million years ago, and ends with the ultimate appearance of Homo sapiens. Two lines of evidence have long existed: one concerning anatomical changes and the other concerning changes in technology and other manifestations of the human brain and hand. Rendered correctly, these two lines of evidence should illustrate the same story of human evolutionary history. They should indicate the same pattern of change through time. These traditional lines of evidence, the stuff of anthropological scholarship for decades, have recently been joined by a third, that of molecular genetics. In principle, genetic evidence has encrypted within it an account of our evolutionary history. Again, the story it tells should accord with what we learn from anatomy and stone tools.
The Origin of Humankind Page 8