The americas' earliest humans section 1: peopling the continent



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THE AMERICAS' EARLIEST HUMANS
SECTION 1: PEOPLING THE CONTINENT

The peoples we call the American Indians are the descendants of the original human inhabitants of the American continents. Culturally and physically, they form a set of distinctive groups contrasting with the peoples of the Eurasian, African, and Australian continents. Evidence now available, drawn from the fields of geology, biology, and archaeology, indicates that hunters began moving through the Americas some fourteen thousand years ago, very possibly earlier. Small bands of people continued shifting eastwards and south from the northern continent while earlier settlers increased in population, until by A.D. 1492 there may have been close to fifty million people in North America, from the Inuit (Eskimo) families ranging the Arctic Ocean to the populous nations of Mexico.

There are differing schools of opinion on when the first humans came into the Americas. These schools may be labeled radical, liberal, and conser­vative, according to their estimates of the validity of alleged evidence for early human occupation. All agree that the earliest Americans came from a northern continent covering what is now Eurasia, the present Bering Strait, and western Alaska.

A radical view is that there have been humans in North America for at least one hundred thousand years, and possibly for one million years. Propo­nents of this extreme position argue that there were probably more periods during which the sea level was low enough that today's narrow, shallow chan­nel between Asia and Alaska, the Bering Strait, was above water, and there was a single land mass encompassing the present two continents. The principal problem in accepting this radical view is that there is no evidence of human habitation in what is now northeastern Siberia before approxi­mately thirty-three thousand years ago (as evi­denced at the Dyuktai site there). It is true that most of northeastern Asia is poorly explored archae­ologically, but there have been several well-car­ried-out Soviet investigations into the prehistory of eastern Siberia and a great deal of recent work by Japanese archaeologists in their homeland, which was once part of mainland Asia. Soviet, Japanese, Korean, and American archaeologists are now col­laborating in conferences and in the field. Both the Soviet and Japanese researchers suggest that Asia north of the temperate latitudes was not colonized by humans until the fully modern physical type (Homo sapiens Sapiens) had evolved and had de­veloped the complex technology of the Upper Paleo­lithic penal (approximately 35,000 B.C. to 8500 B.C.). The premodern humans (Homy erectus) and the protomodern humans (Homo Sapiens neandertha­lensis, or Neanderthal) have not been found be­yond southern Siberia and northern China, the edge of the temperate zone.

The radicals base much of their claim for the great antiquity of humans in America upon a site in southern California cal led Calico Mountain. The site is an alluvial fan (a deposit of soil and gravel washed down from a hillside) in the California desert. On and in this deposit are crudely broken sharp-edged rocks and scattered concentrations of bits of charcoal. Those who believe the site repre­sents human occupation one hundred thousand or more years ago think the rocks are the stone tools of Homo erectus and the charcoal from their hearths. Those who do not accept this claim of great antiquity for Calico Mountain are convinced that some of the rocks were naturally fractured while rolling in the flash floods that contributed gravel to the alluvial fan, and that other rocks were quickly made tools abandoned by Indians hunting in the region in the relatively recent past. The charcoal concentrations are said to be the remains of creosote bushes flamed by lightning. The un­prejudiced archaeologist is most disturbed by the unstable nature of the alluvial fan, in which the rocks could have been naturally shifted from their original positions, and by the consequent lack of secure association between the alleged tools (arti­facts) and means of dating them, such as charcoal bits or geological layering.

There are a number of other finds of crude stone artifacts that suffer from problems similar to those of the Calico Mountain site. The artifacts lie on or near the surface on fans or hillside terraces that may in themselves have been formed many thou­sands of years ago, but that on the other hand have been available for camping right up to the present. Crudity alone does not indicate antiquity for a stone tool, since most people-including you, reader-have at some time picked up a handy stone to break or hammer something, then discarded the stone after use. Only if the artifact lies buried under undisturbed layers of soil, and is closely associated with similarly undisturbed means of dating, can antiquity be accepted.

Archaeologists seeking evidence of early hu­mans in Alaska and in the Yukon in Canada en­counter problems similar to those of the Calico Mountain investigators. Logically, the oldest evi­dence of humans in the Americas should be in Alaska and the Yukon because in the late Pleisto­cene Ice Age, this northwestern section of present­day America was more than once part of the northern continent including Siberia. During the coldest phases of the Pleistocene, so much water was frozen in the huge glaciers that sea level was lower than today, and the shallow Bering Strait between what we know as Siberia and Alaska was dry land, called Beringia by geologists.

Animals moved east and west over Beringia, and human hunting bands could have followed over the cold plains of tundra, grass and sage, and occasional forest. Mammoths, giant bison, cari­bou, elk, wild sheep, and horses grazed the Ber­ingian plains. Searching the gravelly outwashes of Yukon rivers, archaeologists have picked up doz­ens of chunks of mammoth bone that look as if they had been chipped like flint into sharp-edged flakes. Evidence for Beringian humans substituting mas­sive mammoth bone for scarce stone in making artifacts? Or natural breakage of the bone, by tram­pling mammoths or in raging floods? To test one possibility, archaeologists threw an elephant bone into a cage of elephants to see whether their tram­pling would break it up into pieces like the Ber­ingian chunks. It didn't, but the single experiment isn't a final answer. We do know that humans butchered mammoths in the Yukon, at Bluefish Cave, but the radiocarbon date for the occupation is 13,500 t3.c., well in line with conservative esti­mates of humans entering America.

Liberal archaeologists assume that the spread of Upper Paleolithic peoples throughout northeastern Asia brought the most far-ranging bands compara­tively quickly (within a few thousand years) through Beringia into North America. They might have come even during periods of higher sea level, since the Bering Strait is only 56 miles (90 kilome­ters) wide. A couple of small islands rising from the middle of the Strait make small boat crossings easier, and in winter, when the shallow Strait freezes, people could walk over on ice. In clear weather, the tar mainland can be seen from the coasts.

Forests may have been a more formidable bar­rier than the Bering Strait. Forests have a low density of game compared to grassy plains, and forests were probably extensive in both Siberia and America from about 60,000 to 23,000 B.C., when increasing cold led to the last major glaciation, about 20,00() to 12,500 B.C. During this last glacia­tion, mountain valleys and great regions of north­ern America and Asia were closed off by glaciers, but there were always areas of Beringia open to game and to humans, so no span of time can be ruled out for human migration.

What frustrates liberal archaeologists is that much of that part of Beringia most favorable to human living is now below the sea. Historically, human populations in the Arctic have been most dense along the seacoasts where sea mammals such as seals, sea birds, fish, and shellfish provide food that can be supplemented by land game such as caribou and by river fish. The only remnant of the ancient Beringian coast preserved today and available for archaeological investigation is the Aleutian Islands. Excavated villages in the Aleu­tians have been dated only back to 7000 B.C.; perhaps earlier settlements were closer to the lower coastline of their time, and have since been flooded by rising sea levels. Underwater archaeology has been attempted off our present coasts, but it seems to work reasonably well only for salvaging historic ships: ancient sites lie under so much mud they can't be found.

That humans migrated south and southeastward from Beringia into America before or during the last glacial maximum is suggested by a number of finds in Central and South America. It is reason­ably certain that people were living at the far tip of South America, Patagonia, by 10,000 B.C. In south­central Chile, Thomas Dillehay excavated butch­ered mastodon (an extinct elephant adapted to temperate climates) and bits of wooden artifacts and house structures, radiocarbon-dated to 1 1,000 B.C., in a site called Monte Verde. Possible crude stone tools and charred wood were uncovered in a lower, older stratum at the site. Richard S. Mac­Neish recovered bones of extinct sloth and horse with crudely chipped stones that might be tools in Pikimachay (Flea Cave) near Ayacucho in the highlands of south-central Peru, where the lowest, oldest occupation layer is dated to 12,000 B.C. Niéde Guidon, an archaeologist experienced in French Paleolithic sites, exposed a series of occu­pation layers with stone artifacts in Pedra Furada, a series of massive rock shelters in northeastern Brazil; radiocarbon dates indicate the oldest of layers may be from 30,000 B.C., but whether any artifacts are that old is much debated. Pedra Furada does have simple but clear paintings, in red, of people and animals on its rock walls, and these, some dated to 12,000 years ago, establish human habitation in eastern South America contempora­neous with that in the south (Chile) and throughout North America.

Sites in Mexico and the United States give support, but not absolute proof, for the liberal estimate of the time depth of human residence in the Americas. Hueyatlaco in the Valsequillo re­gion southeast of the Valley of Mexico contained what appear to be butchered bones of horse, of a llamalike American camel, and of mastodon, as well as stone artifacts. All of these lay in ancient stream gravels rather than in a stable soil "door" of a camp, so they have been difficult to date, although a geologist's estimate of 20,000 B.C. for the time the gravels were laid down seems not unreasonable. Tlapacoya in the Valley of Mexico, in modern Mexico City, has what looks like a briefly-used camp, with a couple of small flakes of chipped stone and a possible hearth, radiocarbon­dated to 21,000 B.C. Meadowcroft Rockshelter in western Pennsylvania near Pittsburgh has its low­est human occupation layer dated to 12,500 B.C. Meadowcroft's archaeologist, James Adovasio, was excited by the possibility of older dates, but critics point out that no extinct animal bones, only deer and other modern fauna, occur in the rockshel­ter layers.

Conservative archaeologists worry that radiocarbon dates have been accepted too readily. Not only do some researchers write as if "10,850 +/­870 B.C." were a historical date rather than what it really is—the median year in the probable span of years (870 years on each side of the median, that is, the 1,740 years between 11,720 B.C. and 9980 B.C.) within which the assayed plant or animal actually lived-researchers may also be too ready to assume evidence of human occupation was con­temporary with the radiocarbonated material. Soil movement through freezing and thawing, through water flow, through animal digging (even worm burrowing can move objects), and the simple weight of objects, causing them to gradually sink through soil, can all shift artifacts and bone and wood fragments from separate places of origin into proximity. Conservatives demand the kind of proof that řest convinced scientists that humans had arrived in America by the end of the Pleisto­cene epoch: a distinctively manufactured artifact indisputably contemporary with independently dated material.

That first accepted proof of human antiquity in America was a Folsom spearpoint stuck between the ribs of an extinct species of bison. Discovered near the town of Folsom in northeastern New Mex­ico in 1926, the find was viewed the next year, 1927, by a blue-ribbon panel of geologists, paleon­tologists, and archaeologists who agreed that the only reasonable explanation for the stone spear­point in the bison carcass was that the animal had been killed by a human hunter some ten thousand years ago. The distinctive style of spearpoint, beautifully chipped into a leaf shape, then attached, tongue-in-groove, to a shaft by removing a few long, thin flakes vertically up from the base of the point and inserting the thinned base into a slot in the shaft, is called Folsom after the first find site. Folsom points are frequently discovered with bison remains, suggesting these animals were a favored prey of the hunters. Through radiocarbon dating of charcoal or bone associated with Folsom points (since stone never breathed in carbon iso­topes, it can't be radiocarbon-dated in itself), the style is known to have been common around 8500 B.C. For a thousand years preceding (from about 9500 B.C.), a similar style of spearpoint except usually larger and with shorter flakes taken in thinning the base—was in use throughout Amer­ica. This earlier style is called Clovis, after another New Mexico site, and is more often found associ­ated with mammoth carcasses than with bison. Both Clovis and Folsom styles require extraordi­nary skill in flintknapping (chipping stone) to achieve the even, rippled surfaces and "fluted"­-looking like fluted columns on buildings—thinned bases.

There is no question that by 9500 B.C., humans were in America well south of the grassy plains of Beringia west of the Pleistocene glaciation. Right along the edge of the continent-wide glacier was a narrow tundra inhabited by caribou and musk-ox. The western half of unglaciated North America had park-like alterations of evergreen and oak forests with grasslands grazed by small camels, antelope, and ground sloth. Northeastern North America had subarctic pine forests with moose and giant beaver, while the Southeast had mostly de­ciduous forests with deer the principal game. The end-Pleistocene hunters of these several great natural zones left campsites testifying to their highly developed technology both in manufactur­ing stone and bone artifacts and in procuring food and raw materials. East of the Rockies, fluted-base Clovis and then Folsom styles were preferred. West of the Rockies, hunters seem to have pre­ferred hafting their spearpoints by narrowing the base into a stem and then inserting it into a shaft slot, rather than creating a tongue-in-groove fit by "fluting." Fort Rock Cave in eastern Oregon is an example of a site where leaf shaped stemmed spearpoints, associated with other stone and bone tools and with butchered game bones, occur dated to around 1 1,000 B.C.

What puzzles archaeologists is that end-Pleis­tocene sites in Beringia lack fluted-base Clovis or Folsom style artifacts. Fluted-base spearpoints were used in Alaska, but apparently later than to the south in the United States. Apparently the "fluted" thinning of spearpoint bases, difficult to achieve, became fashionable in central and eastern America around 9500 B.C.; while west of the Rockies, in Beringia, and in Eurasia, late-Pleisto­cene hunters preferred less-tricky methods of fit­ting spearpoints into their shafts. Putting aside the one unusual American technique of thinning spear­point bases, the technology and economy of American peoples, beginning at least by 9500 B.C. and continuing to the very end of the Pleistocene Ice Age a couple thousand years later, fit into the general pattern of Eurasian Upper Paleolithic cul­tures. In western Beringia-today, easternmost Si­beria-the Ushki site, dated to 12,000 B.C., exemplifies the local variant of Upper Paleolithic hunters, not dissimilar to Paleo-Indian campsites far eastward in America.

Some idea of what life was like for Paleo-Indi­ans can be glimpsed at Debert, a site in central Nova Scotia, Canada. Radiocarbon dates for De­bert place its occupation at around 8500 B.C. The excavator found what appear to be the floors of ten tents, arranged in a roughly semicircular camp, each tent with two or more fire hearths and with the door opening south. A scatter of broken fluted points and tools lay on each floor. An eleventh concentration of chips of stone and tools lay just west of the tents, and was probably a lookout where the men of the camp manufactured their weapon points and tools while watching for game. In this area was a hearth in which blocks of chalcedony, a fine-grained silicate stone especially suited to making sharp-edged artifacts, had been heated to render them easier to chip. These blocks of raw material had been carried to the site from an out­crop sixty miles away. From the chalcedony and from other types of stone, the Debert people had made and discarded or lost at the camp 140 whole or fragmentary fluted projectile points, 1,600 scrapers (for cleaning the flesh from hides or for woodworking), and 1,000 small wedges used to split bone, which then could be made into scrapers, knives, or projectile points. Fluted-point makers' campsites similar to Debert have been found from Maine to Colorado, dating to the same period.

At about 8000 B.C., the effects of a drastic change in climate began to be evident throughout the Northern Hemisphere. For reasons still not understood-although various theories have been put forth in explanation-great ice sheets covering thousands of square miles in Canada and the north­ern United States and in northern Eurasia began to melt more than they accumulated water as ice over the winters. This was not an overnight phenome­non, but one that fluctuated throughout the last lce Age (Pleistocene epoch) and it was particularly noticeable during the period in which fluted points were made. As the continental glaciers (ice sheets) melted, three effects were felt:

1. The runoff from the melting ice raised the sea level, flooding thousands of miles of coastline even in tropical zones, and in places submerg­ing hundreds of square miles of coastal plain and producing a new coast far inland. The Bering region was thus flooded, and the Bering Strait created. A tremendous number of ar­chaeological sites, the habitats of people who lived near the coasts or hunted on the Bering plain during the late Pleistocene epoch are now lost beneath the ocean.

2. The melting ice gradually freed for human use the northern United States and Canada, where formerly only limited areas, mostly in the West, were habitable. Migrations both northward from the United States, and south­eastward from the habitable territories of Ice Age Alaska and Yukon, would be likely. Plants and animals, as well as people, mi­grated north.

3. The lack of ice sheets in formerly glaciated territories, as well as other factors, caused changes in wind and rainfall patterns through­out North America. These changes, with asso­ciated temperature changes, in turn caused changes in the ecology of most regions of North America, not just the north. Forests re­placed grasslands, or deserts developed. Ani­mal populations shifted as their habitats did. Some animals became extinct, especially the large grazing animals such as mammoths, horses, American camels, and a very large race of bison, at least in part because the grasslands on which they foraged became much reduced in extent. The ending of the last cold stage of the Pleistocene epoch, about 8000 B.C., was both beneficial, in opening the northern half of the continent for habitation, and detrimental, in contributing to the extinction of many ex­cellent game species.

The warming trend continued, with minor fluc­tuations, until about 3000 B.C., when winters in North America were in general a little warmer, and overall conditions drier, than at present. The ecological shifts also continued, at a slower pace, after 8000 B.C., with a few mastodon possibly surviving in the Southeast until close to 4000 B.C. (the evidence is debatable), and the High Plains nearly a desert at the climax of the trend to drier and warmer winters. Much of what happened in American prehistory, as throughout the world, can be viewed in an ecological framework as adjustments to changing environmental conditions. Add the need to adjust to increasing populations (which in a sense is another environmental condition for the people in a society), and powerful stimulants to tech­nological and societal developments are visible.

The past ten thousand years (the Holocene, or present, geological era) have seen the human popu­lation of North America rise from perhaps a few hundred thousand to many million, and differenti­ate from a once-universal hunter-gatherer mode of life into hundreds of distinctive life-ways. Most of this population increase and differentiation was the natural growth of reasonably healthy populations in America. There were probably several Holocene migrations across the Bering Strait from Asia into America, the latest perhaps 2000 B.C., but there has been little scholarly interest in determining any but the earlier ones. In addition to migrations of small groups of people in the early and middle Holocene era, there has been definite contact across the Ber­ing Strait throughout the later Holocene era. Since about 4000 B.C., the Bering region has been ex­ploited by sea-mammal hunters and fi7shermen, historically the Inuit (Eskimos), who live on both sides of the channel and on the larger islands in it, and visit and trade across it. Inuit also traded in the interior of Alaska and southward with the British Columbia Indians. Many ideas and inventions could thus have been traded from Asia to America (or the opposite way) during the Holocene era, but, like the later migrations, diffusion of traded items has received relatively little scholarly attention except when, as in the case of burial mounds, it seems possible to refute any derivation from Asia.

Migration of humans into America is custom­arily viewed as taking place during two periods. The first was in the late Pleistocene epoch and brought bands of hunters across the Bering region from northeastern Asia into America, then south­ward and southeastward. This migration is gener­ally assumed to have been largely completed by the time of Clovis, 9500 B.C. American populations then grew by natural internal population increase until A.D.. 1500, when Christopher Columbus sold Europe the idea of America as a New World of opportunity. The second period of migrations then began. The common assumption of only two so widely separated periods of migration is surely overly simple. But it does emphasize the fact that the development of the native American nations was largely independent of Old World influence; it was the result of the intelligence and abilities of the descendants of the late-Pleistocene and early­Holocene migrants from northeastern Asia.



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