Until the 1930s, it generally was believed that the earliest human inhabitants of the Americas had moved from the Alaskan portion of Berengia to what is now known as North America no more than 6000 years ago. Following the development of radioactive carbon dating techniques in the 1940s and 1950s, this date was pushed back an additional 6000 years to the end of the Wisconsin Ice Age, around 12,000 years ago. During this time the most recent interstadial, or regional dissipation of the massive continent-wide glaciers that previously had blocked passage to the south, opened up an inland migratory corridor. Once settled in what is now the upper midwestern United States, it was supposed, these migrants branched out and very slowly made their way overland, down through North, Central, and South America to the Southern Andes and Tierra del Fuego at the southernmost tip of the southern continent.
Some scholars had long suspected that even this projected date of first arrival was too recent, but it wasn’t until the latter 1950s and early 1960s that they began being taken seriously.1 For it was then, slowly but steadily, that human habitation dates of 12,000 B.C. and earlier from the most southerly parts of the hemisphere began turning up in the archaeological record. In addition, dates of 20,000 to 30,000 B.C. were being placed on sites to the north of these, while more problematic dates of 30,000 B.C. in Chile and Brazil and 40,000 to 50,000 B.C. for skeletal remains discovered in southern California were being claimed.2 By the late 1970s it was becoming clear to many archaeologists that regions throughout all of North and South America were inhabited thousands of years earlier than traditionally had been believed, with some scholars suggesting a date of 70,000 B.C. as the possible time of first human entry into the hemisphere.3
Skeptics remained unconvinced, however. Then Monte Verde was discovered—a human habitation site in a remote Chilean forest with unambiguous evidence (including a preserved human footprint) of a complex human community at least 13,000 years old. The excavated site revealed a dozen wooden structures made of planks and small tree trunks, the bones of butchered mammals, clay-lined hearths, mortars and grinding stones, and a variety of plant remains, some of which had been carried or traded from a locale 15 miles distant, that the community’s inhabitants had cultivated and used for nutritional and medicinal purposes.4 Clearly, since no scientists seriously doubt that the first human passage into the Americas was by way of Berengia, this meant that humans must have entered areas to the north of Chile thousands of years earlier, a fact that was at the same time being confirmed by reported datings of 27,000 to 37,000 B.C. from animal remains butchered by humans in Old Crow Basin and Blue-fish Caves in the Yukon, of 17,000 to 19,000 B.C. for human habitation in the Meadowcroft Rock Shelter in Pennsylvania, of 13,000 to 16,000 B.C. for a site in Missouri, of 11,000 B.C. for human activity at Warm Mineral Springs in southwestern Florida, and elsewhere.5
Then, a few years later, at Monte Verde in Chile again, archaeologist Tom D. Dillehay discovered definite human artifacts that dated to at least 30,000 B.C.—an age that corresponds closely to dated charcoal remains from what are believed to have been human hearths at Pedra Furada in northeast Brazil.6 Since it is a truism of archaeological research that the earliest sites discovered today are always unlikely to be anything temporally close to the first sites that actually were inhabited—both because of the degradation of ancient materials and a site discovery process that makes finding a needle in a haystack a comparatively easy task—there increasingly is little doubt from the archaeological evidence that the northerly parts of the Americas had to have been inhabited by humans at least 40,000 years ago, and probably earlier.7
A welcome recent trend in this research is the attention scholars from a variety of other disciplines, including linguistics and genetics, have been paying to data in their fields regarding the first human occupation of North America. As a result, the earliest dates suggested by the archaeological evidence are now receiving independent confirmation. At present the most intense controversies regarding the early settlement of the Americas in these fields surround work that is being done on DNA linkages and language analysis. Geneticists and biochemists who have studied mitochondrial DNA samples from widely separated native American peoples today have come to equally widely separated conclusions: one group of scientists finds a high level of shared heritage, suggesting that the great majority of American Indians are descended from a single population that migrated from Asia up to 30,000 years ago; another group, studying the same type of data from different sources, contends that their findings point to at least thirty different major population movements, by different peoples, extending back about 50,000 years.
A similarly structured debate exists among the linguists. It commonly is agreed that the people living in the Americas prior to 1492 spoke at least 1500 to 2000 different languages, and probably hundreds more that have been lost without a trace. These languages derived from a cluster of more than 150 language families—each of them as different from the others as Indo-European is from Sino-Tibetan.8 (By comparison, there are only 40–odd language families ancestral to Europe and the Middle East.) Some linguists claim, however, to have located a trio of language families, or “proto-languages,” from which that great variety of languages developed: Amerind, Na-Dene, and Eskimo-Aleut. Others contend that these three proto-languages can be further reduced to a single language that was spoken by one ancestral group that entered North America about 50,000 years ago—while still others argue that the multitude of Indian languages cannot be traced to fewer than the 150 known language families, and that there is no way convincingly to link that knowledge to estimates of the earliest human entry into North America.9
Beyond these specific controversies, however, at least one recent study, building on these data and combining language and geographic research, clearly shows that there already was enormous language and geo-cultural diversity in North America south of the glacial mass during the apex of the last Ice Age—that is, between 14,000 and 18,000 years ago. Language isolates only emerge after very long stretches of time, of course, when a once unified people have been divided and separated for a sufficient duration to erase any linguistic common denominator between them. And we now have linguistic maps of North America showing the existence of scores of independent and mutually unintelligible language groups across the entire continent even before the glaciers of the Wisconsin Ice Age began to retreat. Indeed, although the general direction of American Indian migration was from north to south and from west to east, it appears that certain long established, language-identified peoples—such as some Siouan, Caddoan, Algonquian, and Iroquoian speakers—moved north following the glacier ice as it receded. For as the huge frigid barrier slowly melted, invitingly large glacial lakes emerged, their clear waters trapped between the ice to the north and the southerly high ground, while thick, broadleaf deciduous forests spread northward in the wake of the glaciers’ retreat.10
By at least 15,000 B.C., then, native American peoples on the Pacific coast, in the northern plains, and in the woodlands east of the Rocky Mountains, were living in what by then were age-old hunting and gathering societies that sustained themselves on herds of caribou, musk oxen, bison, moose, mammoths, and mastodons, as well as a large variety of fish and plant life. At the same time, more than 5000 miles to the south—separated by deserts, jungles, and mountains, many of them seemingly impassable by foot even today—distant relatives of those northern coast, plains, and woodland peoples had already become well established and long-settled hunters of South American elephants, horses, camelids, deer, and huge ground sloths, and there is even evidence that by this time gardening cultures had emerged as far south as Chile and Peru. Between these two extremes south of the glacial ice, innumerable other linguistically and culturally distinct peoples had fanned out over millions of square miles of North American, Central American, and South American land and by then had been pursuing their independent lives and cultures for generations beyond memory.
For such linguistic and cultural diversity to have been extant among the native peoples of the Americas at this early date, many different culturally unique Indian communities must have existed throughout both the northern and southern continents for previous untold millennia. And for that sort of widespread migration, elaborate social fissioning, and cultural and linguistic evolution to have taken place, the date of first human entry into the Western Hemisphere has to be placed tens of thousands of years before the end of the Wisconsin Ice Age. Indeed, there are only two good reasons for categorical skepticism regarding an entry date prior to 40,000 or 50,000 B.C.: first, the absence of archaeological evidence for human populations in far eastern Siberia at that early date, the assumption being that this was the area that fed the migration to Berengia; and second, the fact that no skeletons other than those of modern humans have ever been found in the Americas, and modern humans did not emerge and replace Neanderthals, it long has been believed, until about 40,000 or 50,000 years ago. Neither of these, however, are incontestable arguments.
As for the first contention, the failure thus far to locate archaeological evidence for sites older than 40,000 B.C. in such a forbidding landscape as that of Siberia does not mean that they do not—or did not—exist. As archaeologist Fumiko Ikawa-Smith has pointed out, given the weather conditions in this region early inhabitants “may have preferred the milder climates close to the shore, and their remains may have been obliterated by subsequent marine transgressions”—as indeed has happened to early human habitation sites throughout the island Pacific.11 Moreover, far eastern Siberia was not necessarily the sole source of the early Berengian migration: during peak glacial eras Berengia extended well to the south and may first have been populated by emigrants from the cave dwelling communities of Pekin.12 The second assertion has similar problems, particularly since it is now known with certainty (as Louis Leakey long ago claimed, but without definitive evidence) that modern humans did not evolve around 40,000 or 50,000 B.C., but rather came into existence at least 100,000 to 130,000 years ago—while some very recent DNA research puts the date of modern humans’ emergence closer to 200,000 B.C. and even earlier. 13 Although no archaeological evidence has yet been uncovered that would indicate the presence of modern humans in the icy realms of northeastern Asia earlier than 40,000 or so B.C., the entire history of the field of archaeology is testament to the truism that absence of evidence for the existence of a phenomenon is not sufficient grounds for categorically declaring it to be or to have been non-existent; site degradation and loss is a very serious problem in regions such as this—and there is always a new discovery to be made. This is an especially relevant consideration when the temporal gap between archaeological evidence for modern humans in northeastern Asia and in other parts of the world has now yawned open to a range of between 60,000 and 90,000—and possibly as much as 150,000—years.
In sum, there is no necessary barrier to the possibility that humans—whether of modern or pre-modern type—entered the Western Hemisphere as early as 60,000 or 70,000 years ago, although the best scientific evidence to date, drawing on coalescent findings from several disciplines, suggests a more prudent estimate would be for an entry date of around 40,000 B.C., or perhaps a little earlier.
In mapping the pre-Columbian native languages of North America, an extraordinarily dense collection of different tongues are found along the western seaboard, especially between present-day southern British Columbia and San Francisco. (California alone was home to at least 500 distinct cultural communities prior to European contact.) Unless the post-Columbian disease holocaust in the Eastern part of the continent was immensely greater than most scholars now believe, resulting in the extinction of many scores of entire language groups before they could be separated out and distinguished by early European explorers and settlers, the especially thick concentration of different languages along the west coast suggests that to have been the path of earliest human dispersal and settlement.
Whether the earliest southward-moving exodus from Berengia, over the course of many thousands of years, was carried out primarily on land or on sea—or whether the path of the earliest population movements down through North America toward Mexico was along the west coast or through a temporary ice-free corridor in what is now America’s northern midwest—are still other controversies that remain unsettled. Traditionally, it has been held that the earliest migrants south from Alaska had to wait for temporary melts to open inland passageways through the glaciers that blocked their way. Such ice-free interstadials occurred at least five times during the Wisconsin era, each one lasting for thousands of years, with the mid-point of the most temporally distant one located about 75,000 years ago. It now appears increasingly likely, however, that early Alaska inhabitants might not have had to follow an inland path, but rather may have made their way south along the Pacific coastline, either overland, along a narrow, unglaciated, but exposed part of the continental shelf, or by sea, in coast-hugging wooden dugouts or skin boats.14
Since it is known that the first human inhabitants of New Guinea and Australia (which, during the Wisconsin glaciation, was a single land mass) had to carry out at least part of their journey to those lands across a sea gap in eastern Indonesia—and since the initial settlement of New Guinea and Australia occurred at least 50,000 years ago, and probably much earlier—it certainly is possible, perhaps likely, that America’s first people had the technological skills to make seaborne, stepping-stone migrations down the western coastline tens of thousands of years before the end of the last Ice Age.15 Moreover, if that was the primary path of migration, it now is forever hidden from archaeological inquiry, because any coastal settlements or villages that may have existed forty, fifty, or sixty thousand years ago were located on the continental shelf that, like the homeland of Berengia, presently is hundreds of feet beneath the ocean’s waves.16
If the evolving scholarly estimates of the date when humans first entered the Western Hemisphere seem dramatic—changing within the past half-century from about 4000 B.C. to around 40,000 B.C., and perhaps even earlier—the proportionate change is at least equally striking for advances in knowledge during that same time regarding the magnitude of human population in the Americas prior to European contact.
The earliest recorded estimates of New World population came from the first Spanish intruders in the late fifteenth and early sixteenth century. While they of course could make no estimates for lands they had not seen, they did produce figures for the areas in which they had traveled. Bartholomé de Las Casas, for example, put the figure for the island of Hispaniola at between 3,000,000 and 4,000,000 at the time of the Spanish arrival, although Las Casas himself did not visit the island until ten years after Columbus’s first voyage, by which time the population was only a fraction—perhaps 10 percent—of what it had been prior to European contact. Gonzalo Fernández de Oviedo, who arrived in the Americas a decade later than Las Casas, claimed that Panama and the adjacent portion of southern Central America originally held around 2,000,000 indigenous people. And even as late as the eighteenth century Francisco Javier Clavijero claimed that Mexico had an abundance of 30,000,000 people prior to the Spanish conquest.17
Because the post-conquest native population collapses in these and other regions were so massive and so sudden, many later writers found these first estimates—and their implications for an originally enormous hemispheric population—impossible to believe. As a result, by the 1920s there was general scholarly agreement that the combined population of North and South America in 1492 was probably no more than 40,000,000 to 50,000,000 people.18 Within a decade, however, prevailing opinion had dropped even those reduced numbers down to less than 14,000,000—and in 1939 anthropologist Alfred L. Kroeber published a highly influential report suggesting that the population of the entire Western Hemisphere in 1492 was only about 8,400,000—with North America accounting for less than 1,000,000 of that total.19
Recognizing that all these estimates were founded upon a great deal of speculation and very little knowledge of local conditions, Kroeber suggested that work begin on detailed region-by-region analyses. The charge was accepted, particularly by a group of scholars from various disciplines at Kroeber’s own University of California at Berkeley, most notably Carl Sauer, Sherburne F. Cook, and Woodrow Borah. The result was a path-breaking revolution in historical demographic technique that in time became known as the “Berkeley School.” Examining enormous amounts of data from a great variety of sources—ranging from church and government archives listing tribute, baptismal, and marriage records, to the environmental carrying capacities of known cultivated lands and much more—these researchers concentrated their efforts at first on California and central Mexico, extending their inquiries later to regions as diverse as New England, the Yucatan, and the island of Hispaniola.20
The results of these efforts were the most detailed and methodologically sophisticated population estimates ever conducted for the pre-European Americas. And the figures they turned up were astonishing: 25,000,000 people for central Mexico alone and 8,000,000 people for Hispaniola are just two of the more striking re-calculations by members of the Berkeley School. By the early 1960s the accumulated body of such studies was sufficient to allow Woodrow Borah to assert that the pre-Columbian population of the Americas was probably “upwards of one hundred million.” Soon after, anthropologist Henry F. Dobyns published a famous watershed analysis of all the major studies that had been conducted up to that time. His conclusion was that North and South America contained between 90,000,000 and more than 112,000,000 people before the coming of the Spanish.21 Comparative figures for selected other parts of the world at this same time put the population of Europe at 60,000,000 to 70,000,000; Russia at 10,000,000 to 18,000,000; and Africa at 40,000,000 to 72,000,000.22
Subsequently, since the mid-1960s, scores of scholars from around the world have published new pre-Columbian population estimates of unprecedented sophistication for nations, tribes, and regions from northernmost Canada to southern Chile—and for most other major habitation sites lying in between. One after another they have confirmed the general principle that the populations of individual locales were much higher in pre-Columbian times than heretofore suspected. Conservative-minded historical demographers have been reluctant to extrapolate from these findings to overall hemispheric projections, but even the more cautious among them generally now concede that the total population of the Americas prior to 1492 was in the neighborhood of 75,000,000 persons, about 10 percent of whom lived north of Mexico. Others—including Dobyns—have begun to suspect that Dobyns’s earlier maximum of more than 112,000,000 may have been too low and that a figure of about 145,000,000 would be a closer approximation of the true number for the hemisphere, with 18,000,000 or so the best estimate for the region that presently constitutes the United States and Canada.23
Among the reasons for some researchers to have concluded recently that all estimates to date have been too low, is the increasingly acknowledged likelihood that European diseases, once introduced into the virgin soil environments of the Americas, often raced ahead of their foreign carriers and spread disastrously into native population centers long before the European explorers and settlers themselves arrived. In other instances, some Europeans may have been on the scene when the initial epidemics occurred, but these people generally were soldiers more interested in conquest than in studying those they were killing. New archaeological studies in particular locales have demonstrated that this previously “invisible” population loss may have been widespread—a phenomenon that also is now being uncovered among post-European contact indigenous peoples as far away from the Americas as New Zealand, the Pacific islands of Fiji, and Hawai‘i.24 If this did indeed happen on a large scale throughout the Americas, as Dobyns and others now contend that it did, even the higher range of current hemispheric population estimates may be too low. This is because the historical consequence of such archaeological research findings is the discovery that time and again the first European observers and recorders in an area arrived only well after it was totally bereft of its long-established human inhabitants, or at the very least that such observers and recorders found—and incorrectly took to be the norm prior to their arrival—only residual populations so small and demoralized that they provided no hint of true previous population magnitude or cultural vitality.25
Even if certain plagues, such as smallpox, did not always precede the appearance of the European disease carriers themselves into certain regions, however, those who still disagree with Dobyns and his supporters on this point acknowledge that population loss among native societies routinely reached and exceeded 95 percent—a rate of decline more than sufficient to account for a pre-Columbian hemispheric population in the neighborhood of 100,000,000 and more.26 Comparative research in South America and Hawai‘i has shown, moreover, that cultural and biological outgrowths of military assault and epidemic disease, such as severe psychological disorientation and high levels of pathogen- and stress-induced infertility, can by themselves be primary agents in population losses of near-extermination magnitude.27 In sum, while debate continues as to the actual population of the Americas prior to the arrival of Europeans at the end of the fifteenth century, few informed scholars any longer contend that it was not at least within the general range of 75 to 100,000,000 persons, with roughly 8,000,000 to 12,000,000 living north of Mexico—while some of the more outstanding scholars in the field have begun to suspect that the true figure was even higher than the highest end of this range.