The First Americans

by James Adovasio

  Named Homo ergaster and equipped with a substantially larger body (the males may have reached six feet in height) and a proportionately bigger brain than its predecessor's, this species not only was fully adapted to terrestrial life but could also cope with climatic extremes its predecessors could not survive. Homo ergaster appeared in an Africa where the temperature and precipitation regime was changing from coolish and moister to very warm and very dry. They had attained the same body size as essentially modern humans, had lost the hairy body covering of their predecessors, and were probably the first of our remote ancestors to be able to cope with genuinely arid environments. Indeed, with a few minor differences, Homo ergaster is anatomically modern—but only from the neck down.

  Though still not in our league brainwise, Homo ergaster was nonetheless more than intelligent enough to refine, and thereby transform, the Oldowan tool kit into a more sophisticated technology (called Acheulean) and to carry it to parts of Africa where tool-using hominids had rarely or never gone. (This new “Acheulean” tool kit was named for Saint-Acheul inFrance, where it was first discovered.) More significantly, especially from the perspective of this book, Homo ergaster was probably the first hominid to leave Africa for Europe and the Middle East and initiate the trail that would ultimately end in the New World.

  The timing of the initial exodus from Africa into the uninhabited vastness of Eurasia is a subject at least as contentious as that of the appearance of humans in the New World. Based on controversial data from D'manisi in the Caucasus of Georgia, Longuppo Cave in south-central China, and heavily disputed dates from Java, some authorities argue for a very early dispersal out of Africa, as long as two million years ago, well before Homo ergaster even comes onto the scene.

  A more conservative and traditional view places the first African exodus at about 1 million years ago. This view is based on better-controlled information from Ubeidiya in the Jordan Valley of Israel. However, very few other sites exist anywhere outside Africa that are conclusively as old as Ubeidiya, and sites reliably dated between about 1 million and 800,000 B.P. (before the present) are equally rare. Even if the first diaspora occurred at about 1 million B.P. or even earlier, there is scant evidence for a human presence in much of Eurasia until much later.

  Recent reevaluations of the available European evidence suggest only a limited human presence before about 600,000 to 500,000 years ago, though earlier colonizations that failed may have occurred in Spain and Italy. Similarly, with the exceptions noted before, the human penetration of the farthest reaches of middle- and lower-latitude Asia (north China and Java) are rather younger than 1 million B.P.

  “When they got there” is actually less important than the simple fact that they did get there. It is that arrival that constitutes a watershed event in the evolution of the genus Homo. Whether the first sojourner was Homo habilis at 1.9 million years ago or Homo ergaster at 1.7 million to 1.0 million years ago is less important than the elementary fact that two of these creatures did leave Africa and did occupy areas of far greater topographic and environmental diversity than anything “back home.” That they were able to do so speaks volumes not only to their increasing capacity to use culture—inventions of various kinds—to buffer the variability inherent in new environments, but also to the continuing interplay between cultural behavior and continued increases in brain size and cognitive capacity.

  Three factors were critical to the successful penetration of Eurasia. Only one is found in the archaeological record: more sophisticated stone tools such as hand axes and cleavers used for a wide array of chores, the Swiss Army knives of their day. But those foraging hominids needed the ability to control fire and to make tools of wood, bone, and plant fiber, not just stone. All these innovations were needed for subtropical creatures to survive in environments much more severe than any they had ever experienced before. All were essential where episodes of cold, harsh weather were recurrent features of the region—especially at higher elevations in northern latitudes. If, as seems reasonable, the physical and cultural evolution of Homo habilis and its immediate ancestors in Africa was conditioned by a more varied regimen of rainfall brought on by cyclic (and distant) cold spells, their more modern descendants had to cope all the more directly with the effects of seasonal cold.

  Hand axes and cleavers of stone, the hallmarks of the so-called Acheulean tool kit, were fairly widespread especially after 600,000 years ago, but conclusive indication of the use of fire is vanishingly rare. Given the role fire must have played in coping with colder climates in Europe and Asia, this is surprising. What evidence there is of early use of fire is equivocal at best. All the heat-altered sediments, dispersed ash and charcoal, and burned stone tools that archaeologists have turned up at some early sites could just as easily have been caused naturally, for example by lightning. Presently, the best evidence of the human use of fire is no older than 1.5 million to 1.4 million years ago in east and south Africa. That is well after the proposed (and very controversial) early exit from the continent but considerably before the generally accepted date of human dispersal.

  Outside Africa, evidence of the possible use of fire is problematic before about 500,000 to 250,000 years ago, when unmistakable hearths have been documented at a site called Locality 1 at Zhoukoudian in north China. In France, Spain, and central Europe, scant evidence exists, most of it more recent than 400,000 to 300,000 years ago. Actual hearths or fireplaces appear quite late in Europe and the Near East, but this may well reflect inadequate field recognition and recovery techniques, not a genuine absence of fire. Once again, however, the mere presence of humans in seasonally cold areas says more about the capacity of later hominids to adapt than does the incidence of firepits.

  Even rarer than hearths are indications of nondurable artifacts of wood, bone, or fiber. While this is hardly surprising given the highly friable nature of such artifacts in most archaeological settings, their absence has lent undue importance to the relatively common stone tools. This bias in what has been preserved and what hasn't has in turn helped create (and sustain) an image of Late Pliocene and Early Pleistocene technology that is not only wrong for that time but for virtually all later periods. To be sure, stone was an important component of the tool kits of the first wayfarers outside Africa, but it is virtually certain that stone was always a minority element in their technological suite.

  A dramatic and wholly unexpected glimpse of the nondurable part of early Eurasian tool kits was recently recovered under exceptional preservational circumstances at Schöningen in Germany. There, in lakeside deposits nearly 400,000 years old, a series of carefully made wooden throwing spears (javelins) attest to the role that perishable artifacts must have played in the conquest of midlatitude Europe.

  By no later than 200,000 to 150,000 years ago, descendants of the original hominids who left Africa included a variety of forms ranging from robust proto-Neanderthals in Europe and the Near East to “almost” anatomical moderns in Africa and, perhaps, remarkably conservative (at least in an anatomical sense) hominids in southeast Asia. Whatever their appearance, they had much larger brains than their forefathers and -mothers and increasingly sophisticated durable technology, and in most areas had established themselves in virtually the full range of ice-free habitats available across Eurasia. Notable people-free zones were portions of unglaciated central and eastern Europe as well as interior north-central and northeastern Asia, including Siberia. Here the severity of the Pleistocene climate—even in the absence of glacial ice sheets—still posed a formidable barrier to permanent occupation. While it is likely that scattered bands of humans moved into some of these areas during warmer inter-glacials and milder interstadials, they probably retreated as soon as weather took a downturn.

  Of course, at this time (some 100,000 years ago), no human had set foot in Australia—separated from mainland southeast Asia by sixty-two miles of open water—or any part of the entire New World.

  The penultimate steps in the trail to these virgin landsc
apes would betaken not by any archaic representatives of Homo sapiens (neanderthalensis or otherwise) but by fully modern humans of our own genus (Homo), species (sapiens), and subspecies (sapiens). Paleoanthropologists, archaeologists, and geneticists all disagree intensely over the question of whether we emerged with our current cranial capacity and brainpower, as well as our fully modern physiques, only once in Africa or many times around the world (meaning that one species evolved several times from multiple ancestors in several regions—which is, frankly, pretty hard for some to imagine, perhaps all the more so because it smacks of the nineteenth-century polygenism that was so badly tainted by the contemporary racist world-view). For some scholars, this is a fascinating brouhaha, but it actually has very little to do with the main tale of this book. However many “homes” (or points of origin) our single kind may ultimately be able to claim, it was creatures just like us who constructed the watercraft used to colonize Australia and who ultimately took the first unwitting steps into a new hemisphere.

  Unlike their southern seafaring kin, who wound up among the kangaroos and koalas and tropical forests and deserts of Australia, the populations that initially drifted into northeast Asia and Siberia were true children of the cold. They had been shaped by at least nine glacial cycles, at least since they had left Africa, and, armed with a highly elaborated severe-weather technology, these northern colonists were fully equipped to thrive in places where their predecessors would not or could not have gone. Indeed, they had a number of things in common with the woolly mammoths and other gigantic grazers such as oversized musk oxen and now-extinct elklike animals with racks the size of a small automobile that they unknowingly followed into the New World.

  To the anthropocentric and even more to the nationalistic among us, appearing on the same list as one of those large—and probably pretty stupid, even smelly—beasts might seem close to blasphemy, but human evolution works by much the same forces that have shaped other creatures.

  Many of the creatures that lived in relative proximity to the glaciers were large, even gigantic by today's standards. Large size implies, among other things, plenty of good food at the critical times when the body is in a growth period. The edge of the glacier was a region highly productive of good food, at least seasonally. There were streams of fresh water spreadingall over the place, and waterborne silt and windblown loess replenished soils as faithfully as the flooding Nile replenished Egyptian soils until the Egyptians built the Aswan Dam. These were fresh fields, regularly renewed, unlike the old, relatively inert, leached-out realms of warmer climates such as the tropics. Here were plants of many kinds all heavily engaged in rapid and highly intense reproduction, meaning that there was an abundance of especially nutritious parts such as seeds and flowers and new shoots to feed fast-growing young herbivores. (For obvious reasons, if herbivores start growing big, it behooves predatory carnivores to do the same and vice versa in a kind of escalating war.) But something else was going on besides the achievement of sheer size.

  In a few places in the forests of Sumatra, one may still run across a goatlike animal called a serow. It is apparently little changed from the earliest pre-Pleistocene progenitors of goats and sheep, and it is characterized by short, straight, sharp horns—offensive weapons. On the other hand, the mountain sheep of North America and the Mongolian giant sheep have huge horns curved into spirals—hardly useful for goring an enemy though fine for head butting. If they serve as offensive and defensive weapons, they also serve another important function: letting a potential female know how good a male is at obtaining nourishment. They are what are called “wrestling” weapons for arguments over females, and they have even been called “luxury organs,” meaning that the owner possesses the ability to obtain otherwise scarce resources with such skill that he has some left over to produce what might seem like frivolously elaborate organs such as spiral-shaped horns. (One can think here, as well, of the peacock. It is hard to imagine developing so ludicrously elaborate a feature as its glorious tail on a starvation diet.)

  A sheep's horns or a deer's antlers grow only after the animal has achieved its main bodily growth, and most species shed their antlers annually. This means that there needs to be a period of the year when the environment produces a large excess of food over that needed for maintenance (of adults) and growth (of young). Antler growth also calls for special minerals as well as an excess of food availability. Such conditions were fulfilled by the environments near the southern edges of the glaciers.

  Large body size and among males, if not both sexes, elaborate luxury organs such as horns, antlers, and tusks, occur in mammal species whosefemales produce milk high in solids, promoting rapid growth of young, which tend to be large at birth and capable of running soon after birth. Another aspect of this reproductive “strategy” is that the young tend to remain with the parents for a fairly long time. All this, of course, matches the presence of large, fast-moving predators such as enormous bears and large cats. Deer, such as the white-tailed deer that are (comparatively) small and avoid predators chiefly by hiding in the woods and scrublands, don't need huge size or enormous antlers. The big elk and other cervids of the open lands with their extravagant antlers were also long-legged, speedy, high-endurance animals.

  Another luxury item that evolved in glacial neighborhoods was the accretion of fat. Clearly, a bear that needs to hibernate through a long period has to build up fat reserves. Any herbivore that needs to survive the sparse cupboard called winter, scraping away snow to find a bit of dried-up forage, is likely to starve to death (and often does) without an ample supply of fat developed during times of plenty.

  What does all this—or any of it—have to do with humans? As noted, we went from climatically benign environments that changed little in the short run (though greatly over extended periods) to more severe ones, which varied greatly seasonally, from place to place, and over long periods of time. Our teeth became less for biting as we developed other means of offense and defense. We remain among the largest of the primates, though, until the days of the steroid-laced NFL, one could not call us gigantic in the same sense as the short-faced bear. But we outdid our fellow Ice Age mammals in one area of increasing size: the cerebral cortex. This tended to grow in many Ice Age mammals, becoming an organ permitting far greater sociality among such animals as lions and wolves as well as their prey—herds of horses, bison, mammoths, and so forth. But of course, among humans, this organ became far larger (as a fraction of body size) and far more complex than that of any other terrestrial creature in all of the 3.5 billion or so years that life has existed on the planet. It is this powerful organ that lets us imagine, among other things, that we have slipped past any lowly mammalian origins to become a wholly separate sort of creation.

  Other mammalian “luxury organs” of which we are astonishingly fond came about at the same time. Most of us possess to one minimal degree or another a vestigial mammalian covering of hair called fur, whichgrows only to a certain length and then stops. Fur may have become largely vestigial on hominids during their tropical savanna beginnings. But we have bona fide hair—on our head and, among males, on the lower face— that keeps on growing through life (once it starts). Unique to humans, this is very much a luxury item, calling for a constant amount of nourishment to grow healthily, not to mention vast amounts of attention.

  We also happen to be a very fat species comparatively, and not just the couch potatoes among us. Typically, about 15 percent of the overall body weight of a pretty fit adult male human is fat and 20 percent or more among females—not that we need it to hibernate, though it must have been useful when clothes consisted of crudely sewn together hides, not the high-tech thermal wonders of today's mountain climber or skier. Indeed, specialists now consider mammalian fat to be the equivalent of a bodily organ, not only serving as insulation and padding for feet and eye sockets and providing a hedge against lean times, but helping to regulate such important matters as appetite and the immune system. But human evolution added
to these functions.

  Venus of Willendorf.

  In fit humans, fat is concentrated in three regions—the stomach (whereit provides a readily converted source of energy), the buttocks of both sexes, but especially women's, and the female breasts. These features (which are unique in the animal world—no other mammal has permanently large mammary glands or anything resembling buttocks) are both secondary sexual characteristics, as much sexual attractants as an elk's antlers. They bespeak the ability of a woman to feed an infant that needs to be highly dependent for a very long time—unlike, say, a horse's foal—so that its brain can continue to grow in both size and complexity. If the human infant's brain were near adult size at birth, its head would be far too big for the child ever to make it through the mother's pelvis, and if her pelvis were big enough to accommodate an adult-sized brain at birth, she probably wouldn't be able to walk. Like all design, the evolutionary design of the human being has been a series of compromises. Many of the compromises that led to our present design were as driven by the glaciers as those of the woolly mammoth. Taken together, this unspecialized appetite and this particular reproductive strategy are what zoologists call a “dispersal phenotype,” a body plan designed for colonizing new territory, fresh fields, relatively unpopulated places.

  Another aspect of this type of biological strategy is a considerable plasticity of body type within a species. Zoologists point out that the body type (for example, size) of a deer differs with latitude, typically growing larger and faster in more extreme climates and open lands and smaller and more conservatively in the tropics. Similarly, the human body, over generations, has been highly variable, capable of making extraordinary adaptations to differing environments. Consider the huge lung power of the mountain people of Ecuador or the Sherpas of Nepal. Some Eskimos, now properly called Inuits, live in far more extreme circumstances than the people who lived near the glaciers' edges in the Pleistocene; over time they have developed a circulatory system that provides an increased flow of blood to the hands, feet, and other body parts exposed to the extreme cold. In addition, the Lapps, the reindeer herders of the European Arctic, shunt blood from one artery to another paired one, which results in warm venous blood returning from the extremities to the heart. This means that hands and feet can become seriously reduced in temperature without affecting important organs such as the brain and the heart. A bare-chested Lapp in 40°F weather would complain of the heat.