The First Americans

by James Adovasio

  Scientists have found some seventy-six giant ground sloths in the zoological treasure trove of the La Brea tar pits, and the last—meaning most recent—one perished 13,800 years ago. Called a Glossotherium, this was a huge creature with long forelimbs, massive back legs, and a thick tail. Like the anteater, another edentate to which it is distantly related, it walked on the outsides of its feet, which measured up to nineteen inches in length. An awkward, even clumsy vegetarian of the open grasslands, it was small-eyed and small-brained and most likely would have suffered extinction sooner had it not been for its large claws and the bony nodules that turned its skin into something akin to chain mail. A more recent one was found in Florida, dating to about 10,000 years ago, indicating that these big sloths were not among the first to go in what seems to be a terrifyingly sudden extinctionevent in which almost all the large late Pleistocene mammals of North and South America vanished from the planet forever.

  Earlier by a bit more than two millennia, the short-faced bear disappeared from the fossil record, a vanishing act that seems to coincide with the appearance on the scene of the grizzly bear. Some say the grizzly drove the short-faced bear out, but how a smaller, slower creature overwhelmed a bigger, faster one is not clear. Perhaps the grizzly, and the black bear as well, gained an advantage by being omnivorous, while the short-faced bear was limited to meat. But when Arctodus simus vanished, there were still herds of bison and the horse had not yet gone extinct in the Americas, nor had the mammoths and mastodons. And the vegetarian cave bears of the late Pleistocene, much the same size as the short-faced bear, went extinct at this time as well, in both the Old and New Worlds. So what happened in the kingdom of the bears? What made the world a rotten place for huge bears? We simply don't know.

  Similarly, the stag-moose died out about the same time fossils of today's moose appear; was this a matter of competition for the same ecological niche? And what was it about the moose that made it more successful than the stag-moose? Again there is no answer here, just a correlation. Correlations between events or phenomena are not the same thing as causation. One can show that with the increase in the number of streetlights in cities, the crime rate has gone up, but to suggest that light on the streets at night causes crime might not be a tenable conclusion.

  In all, some thirty-three genera of mostly gigantic late Pleistocene mammals were extinct not too long before or not long after the glaciers had receded into Canada. (A genus—plural, genera—is a classificatory group that includes one or more species, so many more than thirty-three species went out of business in this catastrophic period.) The animals that disappeared were almost entirely large—even extralarge—animals. A handful of rodents and other small mammals were extinguished at around this time, but nothing that would otherwise be noticed against the normal background buzz of extinctions that occur all the time. It is clear that the expiration of these thirty-three genera took place in a fairly compact period of time—largely between 12,000 and 8,000 years ago, an eye blink in geological time, though a very long period for a human lineage with only an oral tradition to keep the past alive. After a couple thousand years, whowould remember the Glossotherium except in a generalized way as a monster of myth time? In any event, pinning down exactly when each of these genera was finally lost to the world is now much more feasible than it was a half-century ago, though it remains tentative. The following table provides a glimpse of some of the devastation:

  COMMON NAME GENUS MOST RECENT DATE BEFORE PRESENT

  CHEETAH Acinonyx 17,000

  PECCARY Platygonus 13,000

  SHORT-FACED BEAR Arctodus 12,600

  PRONGHORN Stockoceros 11,300

  WOODLAND MUSK OX Symbos 11,100

  MAMMOTH Mammuthus 10,500

  MASTODON Mammut 10,400

  LION Panthera 10,400

  HORSE Equus 10,400

  CAMEL Camelops 10,300

  STAG-MOOSE Cervalces 10,200

  GIANT BEAVER Castoroides 10,200

  GIANT GROUND SLOTH Glossotherium 9,800

  SABERTOOTH Smilodon 9,400

  TAPIR Tapirus 9,400

  In this list, as in more complete ones, the apparent extinction dates cluster between 11,000 and 9,500 years ago. This was the time that the climate, local weather, and ecosystems of North America were undergoing a spectacularly rapid upheaval. It is also the time when other creatures that could also be called charismatic megafauna thrived—the hunters of the Clovis culture and the ensuing Folsom culture. Both factors—climatechange and the mighty hunters of Clovis and Folsom—have been indicated in the cataclysmic end of the giant mammals of the New World.

  What was left after the major extinctions had occurred was a host of medium and small mammals ranging from beaver and raccoons to mice and moles; largish prey animals consisting of today's bison, bighorn sheep, mountain goats, pronghorns, mule and whitetail deer, elk, moose, caribou, and musk ox; and predators consisting of polar bears, grizzly and black bears, mountain lions and other relatively small cats—such as ocelots, lynxes, and bobcats—foxes, coyotes, and a handful of wolves. For the first Americans, things had changed dramatically from those grand adrenaline-filled millennia south of the ice sheet when the world was new and terrify-ingly aswarm with giants.

  Because the timing of the extinctions, particularly as they were understood in the 1960s (that is, as almost simultaneous), coincided with the presence of Clovis Man, the conclusion to be drawn was elementary, at least to a certain professor of geochronology at the University of Arizona, Paul S. Martin, and a colleague of his in Tucson, C. Vance Haynes, who would soon become the bêtes noires of anyone who even dreamt of preClovis archaeological sites.

  PLEISTOCENE OVERKILL

  In the late sixties, Paul Martin was a rawboned, crew-cut gent with a high, domed forehead and the squint lines of someone who spends a lot of time out of doors. He boldly announced a theory that pegged Clovis Man, the earliest known progenitor of the American Indians, as the most voracious and insatiably reckless hunter of game the world had ever seen.

  This was a time when the word “ecology” was escaping from the journals of science into the public mind and the American Indian was beginning to be revised into something of a natural ecologist or, as Martin put it in a December 1967 article in the popular magazine Natural History, “the noble savage, a child of nature, living in an unspoiled Garden of Eden until the discovery of the New World by Europeans.” That same year Martin published a technical work, Pleistocene Extinctions, on which his article was based.

  Now, Martin was not the first to point out that a lot of big mammal species had gone extinct toward the end of the Pleistocene, and of course it had been known since the 1930s that Clovis Man had killed at least some mammoths. Indeed, long before Martin, an environmental scholar named Carl Sauer had proposed that early man had wiped out the big-game animals in North America by using fire drives. This was before radiocarbon dating began to pin down the dates, so most people had rejected the idea, based as it was on virtually no evidence except accounts of historic Native Americans burning grasses to hunt and to encourage new growth the following year. Still, the general understanding before Martin's announcement in 1967 was that the extinctions had been caused by sudden climatic change brought on by the retreat of the glaciers. Hotter summers and colder winters would have upset the breeding seasons, with reproduction coming at a season when the young could not survive. Accelerated competitionamong the big mammals would also have occurred, and they would have wiped out their food supply. When Clovis Man showed up, having recently crossed the Bering land bridge, he administered the coup de grâce to the remaining badly depleted herds.

  Ludicrous reconstruction of Clovis hunters confronting an Ice Age bear.

  Paul Martin, however, pointed out that habitat such as grassland appeared to be improving as the Pleistocene ended. Why would such grass-eating species as horses go extinct when there was plenty of grass? Why would spruce-eating mastodons go extinct when spruce forests were extending north
ward, following the receding glacier's edge? The unprecedented snows of severe winters could hardly be blamed for these mass extinctions since numerous tropical species had gone extinct in this period. Indeed, Martin looked at the matter globally, quoting Pleistocene experts as all agreeing that the big climatic changes of the previous 50,000 years had occurred simultaneously around the world. But, he said, the extinctions of large mammals had coincided with only one thing: the arrival of humans on the different continents and islands. Martin pointed out that in Australia, for example, various big marsupials had vanished around 14,000 years ago, just after, it was then thought, people had arrived. Hepointed to the giant birds called moas that had survived the Pleistocene on New Zealand but had been extinguished by the late-arriving Maoris on those islands about a thousand years ago. Examples abounded.

  Clovis hunters sprinting south, leaving a trail of projectile points and dead megafauna.

  “My own hypothesis,” Martin wrote, “is that man, and man alone, was responsible for the unique wave of Late Pleistocene extinction—a case of overkill rather than ‘overchill‘ as implied by the climatic change theory.”

  Africa stood out in most minds at the time as an exception; the great wildlife spectacles of that continent were often billed as comparable to those of America's Ice Age landscape—and of course, humans had been in Africa long before the late Pleistocene extinctions had taken place around the world. Martin explained that some 30 percent of Africa's wildlife had indeed gone extinct in the late Pleistocene—such creatures as giant pigs, giraffes with antlers, and giant sheep. This was a significant extinction, if not as severe as that in the Americas, and Martin ingeniously pegged it to the development of fire as a tool and hunting strategy by African people around that time. As for North America, when people first swept in through the

  melting ice corridor east of the Cordilleras, we can be confident that they were old hands at hunting wooly mammoths and other large Eurasian mammals. In contrast, the New World mammoth and other species of big game had never encountered man, and were unprepared for escaping the strange two-legged creature who used fire and stone-tipped spears to hunt them in communal bands…. In any case, radiocarbon dates indicate that North American extinction followed very closely on the heels of the big game hunters. The Paleo-Indians easily found and hunted the gregarious species that ranged over the grasslands, deserts, or other exposed habitat. As the hunters increased in number and spread throughout the continent, large animals whose low rate of reproduction was insufficient to offset the sudden burden of supporting a “superpredator” soon perished.

  The migration of humans into the Americas soon came to be seen as a blitzkrieg wherein a band of as few as a hundred wandering Eurasians, led by maybe twenty-five male superpredators, burst through the ice-free corridorinto midcontinent. Overnight they invented the Clovis point and, in an unprecedented (among hunting societies) population explosion, swept across the continent at a spectacular pace, reaching the tip of South America—a distance of some six thousand miles—in five hundred years or less, along the way wiping out practically everything that both moved and weighed more than a hundred pounds, as they colonized (and then extinguished) the previously innocent animal kingdoms of North and South America.

  How was it that any big species survived the superpredator? Those that went into the woods—bears, moose, woodland bison, deer—could have evaded Clovis Man, hidden away while Clovis and Folsom hunters slaughtered the last big herbivores in open country. Musk oxen, those shaggy beasts of tundra and snow, were wiped out in Eurasia but survived in North America only, Martin suggested, because part of the population was stranded north of the glacier in what was called the Greenland Refuge when Clovis Man went blitzing through. When the ice finally melted back to its current configuration some six thousand years ago, musk oxen were again exposed to humans. But by that time these humans—mostly Eskimos—had fortunately learned about sustained yield. The wandering superpredators were no more.

  While it never found anything like unanimous agreement among the scholars concerned with that era, the Pleistocene Overkill theory swept the country with Clovis-style speed. Conservative pundits, sportsmen's groups, and right-wingers in particular found it especially useful, while American Indians and their supporters not surprisingly found it totally disagreeable. As late as 1995, Vine Deloria, Jr., the sometime political scientist and full-time activist from the Sioux Nation, railed against the idea. In Red Earth, White Lies, an impassioned (and largely ill-informed) diatribe against the matter of human evolution, the existence of the Bering land bridge, and the continuing failure of the sciences to confirm the creation stories of Native American myth time, he attacked Pleistocene Overkill as merely another politically motivated assault on the moral values of his people. In response to such assaults, he denied the underpinning validity of any and all science, its findings, and its methods, including any result whatsoever from radiocarbon dating—except one he quoted of 38,000 years B.P. that apparently embarrassed scientific dogma. (As we have seen, a carbon-14 date of thatage is by its very nature unreliable.) To unshakeable true believers like Deloria, biblical creationists, and others who are selectively antiscience, there is, of course, simply nothing to say.

  In science, however, theories are put forth as hypothetical explanations of certain observations, not as “facts.” They are then tested against the world in a variety of ways and almost always revised a bit or a lot (or thrown out) in the light of new information—new observations or new light shed on old observations. Science is less a matter of creating facts than a process of reducing ignorance, but some people always prefer the bliss of ignorance. Scientific theories and propositions can be upsetting to established beliefs, and Martin knew from the outset that his idea was going to be upsetting—and not just to Native Americans.

  In the late 1960s, people were beginning to talk about the unfortunate results of importing species of plants and animals into one continent that had evolved elsewhere. Starlings, for example, were brought into New York City by a romantic in the late nineteenth century who had the idea of importing every bird mentioned in Shakespeare to this country. They soon became a terrible menace to native songbirds all across the continent, taking over their territories and nesting sites. Tumbleweeds, the scourge of the arid West, had arrived accidentally as seeds on ships. Mynahs, goats, and other alien animals were eliminating the native fauna of Hawaii. The wisdom of bringing in game animals from places like Africa—such as oryxes—and setting them loose for sportsmen to chase was under serious scrutiny.

  According to Martin, however, the evolution of new species and the extinction of old ones go hand in hand. In normal times, he said, all the available niches are filled, and as a new species evolves, it outcompetes an old one for the same ecological niche and the old one is extinguished. But in North America, with some thirty genera extinguished practically overnight, new species did not evolve to take their place. Thus, he pointed out, when horses were returned to North America by the Spanish and some of them escaped into the wild, they found plenty of room on the grasslands they had once inhabited and formed large wild herds. So perhaps bringing in the likes of oryxes was a good thing, he suggested, filling in niches left empty for millennia by the marauding of Clovis Man.

  The growing number of ecologically minded wildlife biologists andrange managers did not think much of Martin's notion, and it turned out to be a major oversimplification of ecological and evolutionary processes. But that is not our concern here. It is sufficient to point out that what can seem to be merely an academic matter, of little relevance in the real world, can on the contrary have considerable ramifications outside the academy. People in the late sixties and beyond who were resisting the growing environmental movement were happy to see the American Indians—something of an environmentalist icon—discredited as the descendants of ecological ravagers—and this did no one any good.

  H. L. Mencken, who knew very little about science and its methods, said someth
ing wise that applies to science as well as many other fields of endeavor. “For every complex problem,” he wrote, “there is a solution that is simple, neat, and wrong.” By now, the Pleistocene Overkill theory has lost credibility, except, of course, with Martin, who believes it more firmly than ever, and a handful of acolytes who are not attempting its resucitation. However, not everyone in the field bit even in 1967, and virulent disagreement has continued for decades. Martin continued to argue that a small group, bursting on the scene and being well fed by the slaughter of huge and even wasteful amounts of meat on the hoof, could have reproduced at the astonishingly high rate of 3.4 percent annually, thus increasing the overall population size dramatically and far beyond the average rate (0.5 percent) of any ethnographically documented hunter-gatherer group. Not only would they have had to be copulating machines to accomplish this, they would also have had to have much lower infant mortality rates than are typical of hunter-gatherers. If they also managed to migrate on average some ten miles a year, they would have constituted an expanding wave of amazingly efficient and fecund killers that could have reached Tierra del Fuego (and every other part of the hemisphere) in less than a millennium.

  But many scholars wondered how Clovis hunters could in truth have reproduced at a rate so much greater than other hunting and gathering societies are known to reproduce. Martin evidently got his 3.4 percent rate from the experience of the mutineers who fetched up on Pitcairn Island after throwing Captain Bligh off H.M.S. Bounty— and apparently they were copulating machines! (Why Martin chose the Pitcairners is hard to imagine except for the fact that precise data existed about them, whereas itwas harder to come by in the ethnographic literature about tribal people.) Furthermore, hunters and gatherers typically move before all the resources in an area are used up, largely because the obtaining of food becomes arduous enough to make moving worth the extra effort. Also, small groups of people, such as little daughter bands, tend to stay within reach of the mother band so they can reassemble periodically to find mates or to replace those lost to fatal accidents. And of course fatal accidents would be all the more likely among people who hunted mammoths on any regular basis. These animals were almost three times as tall as any Clovis hunter, weighed as much as seven tons, and (if they were anything at all like modern elephants) unpredictable and even vengeful, as well as immensely powerful.