The First Americans

by James Adovasio

  This so-called Spokane flood was surely one of the most appalling floods in the continent's existence, but the many floodwaters pouring outof glacial lakes and the glacier itself from about 25,000 to 7,000 years ago had to have been one of the dominant terrors facing any sentient beings present. Woe surely betided any creature downstream of an ice dam when it gave way.

  Given the chance, of course, water will make maximum haste downhill and back to the oceans from whence it came. What had begun as fairly gentle braided streams and rivers issuing out from beneath the advancing glacier would have turned into land-gouging torrents, roaring across the landscape to the sea. The huge Mississippi drainage that extends today from the Rockies to the Appalachians essentially came into being in this period as millions of cubic miles of water were freed from the ice. One source was a vast lake called Lake Agassiz, five times the size of Lake Superior today. Its waters flowed into the Mississippi system and at least once, when some dam of ice or debris gave way, sent a blast of water downstream strong enough to move the giant river into another valley altogether.

  In addition, some excellent real estate on the eastern and western margins of the continent was being inundated by the rising sea levels, and wildlife and people were forced to migrate inland before the tide. As the salt water rose, it filled the mouths of some of the great, rushing rivers, slowing them down and forming marshes and bays large and small. Chesapeake Bay and San Francisco Bay, the two largest bays in the lower forty-eight states, came about at this time. Seawater created sounds, such as Puget Sound, and inland seas that, as the land rose, became landlocked and in due course turned into freshwater lakes. New York's Lake Champlain was one of these. By 10,000 years ago, Beringia was dry land no more, but it persisted for a while under shallow water that could be crossed by large mammals, humans included, when the water seasonally turned to ice. The rate of the oceans' encroachment on land was occasionally slowed by the rising of the earth's crust as it escaped from the weight of the glacier; some places, such as the coast of Maine, are still rising slightly. Elsewhere, the huge pluvial lakes of the Southwest were shrinking, evaporating, leaving increasingly salty waters behind, until most of them were nothing more than a monotonously flat, dead, white, and rapidly diminishing memory in the genes of migratory birds.

  Estimates suggest that as the result of changes in the earth's orbital positionas well as a rise in atmospheric carbon dioxide, solar radiation increased near the southern margin of the ice sheets by about 5 percent over the 5,000 years beginning 15,000 years ago. The increase in temperature not only doomed the glaciers' southern extremities but also led to the evaporation of the pluvial lakes, lower rainfall in the Southwest, greater rainfall over and near the ice, the decay of alpine glaciers, the rise of mountains' tree lines, and a host of other changes that altered the landscape at varying rates and in a patchwork of outcomes.

  One such change took place in the Southwest, where mountains and small chains of mountains are often isolated in the middle of large flat areas in what is called basin and range topography. Here, as the lowlands heated up and approached the status of desert, plants and animals that had thrived in colder, damper times would have been outrun by the climate, unable to migrate northward toward suitably cooler areas fast enough, so they had no place to go but up. As a result, today you can drive up the mountains that loom over Tucson in southern Arizona, for example, where summer temperatures are typically above 100° F., and in the course of an hour pass through five distinct ecological zones ranging from dry Sonoran desert lands to the more humid summit with approximately the same climate and the same vegetation as the lands around Hudson Bay, 2,000 miles to the north. The marmots, Engelmann spruces, and other subarctic life-forms isolated high up on these “sky islands” are direct and literal relics of the Ice Age.

  During the Clovis era, which began about 11,500 years ago and continued for a few hundred years thereafter, the living things of North America were undergoing what was one of the more traumatic times in the history of the earth. For people living here at the time, the world may well have seemed an unstable place. Familiar animals might suddenly disappear, seeking their favored food, which had also gone somewhere else. What might have been a good place for your parents might change into something that would not support you. People would have been on the move.

  The shifts in overall climate, regional weather, and some, but not all, local weather profoundly altered even those stately, semipermanent, and slow-to-react ecosystems called forests. We tend to think of forests as coherent communities consisting of several species of trees, some of which are dominant, even diagnostic. They change very slowly—after all, a mapletree can live for four hundred years, so something that suddenly makes it difficult for maple seeds to germinate may have little immediate effect on a maple forest. But 10,000 years ago, in parts of the Midwest, spruces that had reigned supreme for millennia gave up the ghost in a mere century and a half.

  On the other hand, ponderosa pines, those grand sentinels of our high, parklike forests, spread like weeds from a few cool places in the South to cover the upper reaches of the Rocky Mountains. Deciduous trees—oaks, hickories, maples, beeches—moved north and all about, each species responding in its own time and with its own speed to the changing local conditions. Some trees moved north thanks to windborne seeds, but one of the more efficient tree movers was the jay, which developed the habit of running off with the acorns of oak trees and depositing them in little caches on the edge of the forest, where the sun might raise them into trees. At this time of the world, oak trees moved at the rate of about a thousand feet a year—or two hundred miles in a millennium. In many regions near to and far from the edge of the ice, what appear to have been patchwork quilts of differing plant communities (and, on the edges where two or more plant communities met and mixed, even more complex plant communities) became more uniform. This was, in fact, an unscrambling of plants and their communities back to a previous, preglacial state. The glacier's edge had brought about situations where plants and animals from separate ecosystems had been thrown together; now, in this newest warm period of the many that punctuated the million and a half years of the Pleistocene, they were dispersed again.

  One result was a great many more species going extinct, not unlike what had happened in all the previous interstadials. These ecological changes were driven, of course, by the relatively rapid climate change that brought on the relatively rapid disintegration of the glacial ice: by 7,000 years ago, the ice was about what it is today in extent and location. The particularly important results of the overall climate change under way were the reestablishment of four-season continental climates and the increase in seasonal extremes—colder winters, hotter summers—which unquestionably stressed the creatures that had adapted to somewhat more consistent year-round conditions. There's only so much cold a southern white pine can take, for example, and only so much summer heat a bluespruce can live through. In this chaotic late Pleistocene–early Holocene period, the limits of everyone and everything were being tested. Creatures needed to readjust to new ranges. Among mammals, size transformation proved a more salutary strategy than the conservative one of simply sweating it out: the 350-pound beaver gave way to a successor more like today's, for example, smaller in size and behaviorally more clever. Changing patterns of precipitation (and evaporation) would have created similar challenges. New habitats were being created in virtually every part of North America, a shifting kaleidoscope of ecosystems that meant tremendous change for any creatures present, including humans.

  In many regions, especially in the lands west of the hundredth meridian and east of the Sierras in California, the result of intensifying seasonal extremes was the creation of far less diverse communities—what are called monocultures. The vast plains in the nation's midsection began to sort themselves out into broad, vertically striped regions of long-grass, medium-grass, and short-grass prairies in response to different moisture regimes and seasonal differences. This was all to th
e good for bison, which proliferated along with many other grazers, though it favored smaller animals. The gigantic bison of the late Pleistocene—a huge creature with long horns—gave way to smaller and smaller species until, for a time at least, today's Bison bison became (along with the wildebeests of Africa) one of the most numerous grazing species the world has ever seen. Similarly, the condor that was ancestral to today's California condor, a bird with a ten-foot wingspan, was Teratornis terribilis, twice the size of today's version with a wingspan of twenty feet, one of the largest feathered flying birds ever. Such a bird, soaring overhead spying out a corpse, would have blanked out the sun for a noticeable moment and, for my money, could have been the creature that gave rise to the Thunderbird of American Indian legend.

  All of the Europeans who saw the great herds of bison on the American plains and wrote about them were at a loss for words to describe their numbers, the thunder of their passing, their sheer multitude. One of the earliest European witnesses to the great bison herds was Fray Alonso de Benavides, custodian of missions in New Mexico in the late 1620s. In a Mission (report) to King Philip IV of Spain in which he described this now-thirty-year-old addition to the Spanish empire, he wrote of the bison, “Ihave dwelt on these cattle because they are so numerous and widespread that we have found no end to them.… There are so many of them that they blot out the plains. These cattle by themselves would be enough to make a prince very powerful, if he had or were given a means by which to convey them elsewhere.” That is hardly poetry, but then NASA sent no poets to the moon either. In any event, until they became a market commodity for consumption and use by people other than the local Plains Indian tribes, the vast bison herds, paralleled only by the caribou in the Arctic and Subarctic, were the last truly astonishing wildlife spectacle in temperate America. Even those enormous herds were probably pretty thin soup compared with what the first Americans stumbled onto when they made their way south of the ice. This astonishing animal life of late Pleistocene–early Holocene America was part of the promise—and part of the terror—that the small bands of the first Americans faced. Whenever they got here, at whatever time they arrived, and by whatever route, they found themselves among not only myriad sources of meat on the hoof but also a spectacular array of large, swift predators with which they might have to compete—or from which they would need to escape. In those days, sharing the world with wildlife had a somewhat different connotation from what it might today.

  CHAPTER THREE

  CHARISMATIC MEGAFAUNA

  The mammoth stands in its final agony, the oily black ground giving way under him, sucking at his legs, while a ferocious lion snarls, mouth agape, lethal fangs glistening. Enormous vultures, those handmaidens of death, await the end in solemn congregation, their huge wings folded over their backs. Scenes like this must have taken place often throughout much of the continent over the eons, as well as right here amid the sounds of the internal combustion engines roaring along Wilshire Boulevard between Fairfax and La Brea Avenues in Los Angeles. For this is the site of the La Brea Tar Pits, the single most productive source of the remains of the grand megafauna that roamed the North American continent in the late Pleistocene age. Judging from the museum's confident reconstruction of the mammoth's final hours, as well as numerous museum dioramas elsewhere and countless paintings and illustrations of this late Pleistocene/early Holocene bestiary that have appeared over the years in museum dioramas, books, magazines, and elsewhere, you would guess that there isn't much we don't know about those creatures and their world. But among the many unknowns are why they died out and exactly when. Another unknown is exactly how important a factor these large mammals were for the first Americans, whenever it was that they arrived here.

  For example, it is hard to imagine that the first Americans could easily have avoided the attentions of the several species of lions that stalked theherds of huge bison and other grazers. Or the clutches of the short-faced bear, a predator that stood as high at the shoulder as a moose and could probably run, at least in spurts, as fast as the camels and horses that, among other prey, it ate. Known to science from minimal remains and called Arctodus simus, this graceful monster was almost certainly the most dangerous predator that roamed Ice Age America. Not long ago, a Russian paleontologist visited the Natural History Museum in Utah and was shown the largest short-faced bear femur known—it was longer than an entire human leg. The Russian erupted in exasperation, asking “Why does the United States have the biggest everything on the planet?”

  It is hard to imagine that this gigantic bear, capable of rearing up to some fifteen feet or higher, does not still lurk somewhere in the cultural memory of the first Americans' descendants—in their worst nightmares and perhaps in their stories of myth time. Could they have become the giants that in Navajo histories of the beginning of things had to be killed by the monster-slaying hero twin sons of the sun so that the world could become safe for people? Some scholars of the ice ages, in an only somewhat more scientifically tenable suggestion, have opined that human beings (who have enough trouble killing a brown bear with so rudimentary a weapon as a spear) could not have settled and survived in North America until the short-faced bear went extinct.

  Short-faced bear, Arctodus simus, drawn by Bill Parsons.

  And where are the elephants in American Indian stories? After all, their ancestors—those highly carnivorous people called Clovis—supposedly hunted these great beasts, maybe even to extinction, and made them a principal part of their diet, along with giant ground sloths and the other vast mammals that roamed the warming plains and plowed through the expanding forests and swamps. In fact, there is at least one vestigial tale that suggests a memory of an elephantine presence: the Beothuk people of Newfoundland (who probably were the “skraelings” who harassed Leif Eriksson and the other Vikings when they showed up there out of the northern mists, a millennium ago) had a story about a monstrous quadruped with a long, pendulous nose. But all such speculation about the origins of myths and dreams, though wonderful fun, is just that—speculation—and as lacking in any means of resolution one way or another as are the tenets of Jungian psychology or the disputes of postmodernist literary critics.

  By as early as the 1920s, scientists knew a great deal about the kinds of animals that roamed Ice Age America. Charles Knight painted enormous murals in the American Museum of Natural History in New York, images that are basically fixed in the recesses of the public mind that dwell even briefly on this amazing era. Other images were not long in coming, and still today one sees in popular books, especially for kids, those wondrously crowded landscapes with herds of bison and other grazers, stalked by every kind of predator, and in the cramped, oblong foreground sloths and other bizarre specimens going about their business, mostly oblivious of one another. Probably they weren't really quite so crowded.

  We learn more about such creatures all the time. As this chapter was being written, paleontologists from the Denver Museum of Natural History announced the discovery in Porcupine Cave in Colorado of a particularly rich cache of Pleistocene mammals that dated back more than a million years, including some of the earliest known remains of such animals as cheetahs in North America. Was the cheetah an African beast that spread to here, or vice versa? We don't know all the answers even today. But we do know that the woolly rhinoceros that patrolled Europe and parts of Asia never made it to the New World. To this day no one knows why. Perhaps it was simply a matter of timing, which, when it comes to migrations through glacial environments, was as important as it is in show business.

  AN ICE AGE BESTIARY

  Through the 1.6 million years of the Pleistocene, the glaciers came and went on a schedule of approximately every 100,000 years, with 10,000- to 20,000-year warm interglacials in between. And remember that even during the glacial periods, there were times when things warmed up somewhat.

  Ice Age camel, Camelops herternus.

  A migration from Asia across the Bering Sea needed to take place during glacial tim
es, when the ice lowered the sea level enough to create Beringia (which was open for migratory business during much of the Pleistocene). Even earlier, in a warmer epoch altogether called the Pliocene, local glaciers, though nothing like the huge ice sheets of the Pleistocene, came and went in the north as well as on Antarctica, and a land bridge sometimes emerged between the two continents.

  At various pre-Pleistocene times, then, Old World animals made it across to the New World. Many of these, like ancestral hyenas, were long extinct in the Americas by the time of the last great ice advance. Although North America would become a major zoological melting pot, it did also produce its own originals. Horses originated in North America as small three-toed creatures of the woodlands, and by late Pleistocene times they were much like today's Grevey's zebra, perhaps even with similar markings. Meanwhile, other equine forms—asses, true horses, and the unfortunately named half-asses—had evolved and were passing back and forth between the New World and Old World like commuters, so much so that it is still not clear if true horses and asses arose first in the New World or the Old. Camellike animals had their beginnings in the New World as well, producing three strains—in the ice ages—that were giant forms: camels with one hump like today's dromedary, llamas, and llamalike camels with humps. Gigantic tortoises, larger than those seen in the Galápagos Islands, waddled about, and beavers reached the weight and size of brown bears, some 350 pounds, but acted more like muskrats than dam-building beavers. Sloths were New World creatures and remained so, failing to make it past the ice into Asia. In the meantime, Old World mammals migrated here in great and noticeable quantities.