Biological and cultural roots of the Native Americans
Dental morphology, genetics, and archaeology show that the biological and cultural roots of the Native Americans lie in northern China and extreme northeast Asia. We do not know when modern humans first settled in China. Although Chinese archaeologists claim that Homo sapiens sapiens evolved independently in the Far East, they have yet to put forward convincing evidence for such a hypothesis. Anatomically modern people were hunting and foraging in the Ordos area of Mongolia by 35,000 years ago. Ten thousand years later, a vast area between Mongolia in the west and the Pacific coast in the east supported a highly varied population of hunter-gatherers exploiting game and plant foods as well as coastal resources. As time went on, their tool kits became progressively smaller and more refined. They produced tiny stone blades used as lethal spear barbs and small scrapers; they also relied on artifacts made of wood and bone. This so-called microblade technology spread widely in northeast Asia, offshore to Japan, and north into Siberia.
The earliest human settlement of extreme northeast Siberia
The earliest human settlement of extreme northeast Siberia, from Lake Baikal eastward, took place late in the Ice Age. This was after the last glacial climax 18,000 years ago, when warmer conditions opened up hitherto uninhabited steppe-tundra. The first settlers were few in number, living off big game, plant foods, and perhaps fish and sea mammals. The middle Aldan River Valley began to support bands of late Ice Age people using microblade technology 15,000 years ago, perhaps earlier. These same people settled as far northeast as the Bering Strait.
A land bridge from about 100,000 to 15,000 years ago
A low-lying land bridge joined Siberia to Alaska during the entire Würm glaciation, from about 100,000 to 15,000 years ago. During glacial maxima, the land bridge was a wide, poorly drained plain, swept by arctic winds. The climate was dry and intensely cold, with only a two-month summer. Low scrub covered the landscape, except in shallow river valleys where some trees and lush grasses grew in spring and summer. During warmer intervals, sea levels rose, flooding much of the plain, leaving but an isthmus between Old World and New. This was the route by which humans settled the Americas.
Claims of very early settlement
Claims of very early settlement are based on a series of cave and rock shelter finds in South America. There are affirmations of humans occupying Boqueirao de Pedra Furada in northeastern Brazil at least 40,000 years ago. Only a few scholars accept this claim or other much heralded occupations said to have occurred between 40,000 and 25,000 years ago. The most widely accepted scenario has small numbers of hunter-gatherers from northeast Asia crossing into Alaska as the land bridge began to flood at the end of the Ice Age some 15,000 years ago. This was not a journey of exploration but rather part of an age-old hunter-gatherer lifeway that had people following migrating game and searching for new clumps of scarce plant foods.
The earliest archaeological evidence
The earliest archaeological evidence for human settlement in Alaska—nothing more than small scatters of stones and bones—dates to about 11,500 years ago. From that date onward, there has been continuous human occupation in the Arctic into modern times. During the height of the Würm glaciation (called the Wisconsin in the New World), northern North America was mantled by two vast ice sheets that extended from Greenland to British Columbia. There may have been a narrow, ice-free corridor between them, but it would not have supported animal or plant life. Most likely, people from Alaska hunted and foraged their way south onto the Great Plains as the ice sheets receded rapidly after 13,000 years ago. Despite occasional occurrences of 12,000-year-old artifacts in North America, the first widespread settlement of the Americas as a whole dates with great consistency to about 11,000 years ago (9000 B.C.E.). Within a few centuries, perhaps no more than 500 years, hunter-gatherer groups had colonized the entire Americas, from ice-free Nova Scotia in the north to Patagonia in the south.
The Clovis people
The Clovis people (named after a site near Clovis, New Mexico) are best known for their characteristic stone projectile points, fluted at the base for mounting in a wooden shaft. These people preyed on game of every size and also foraged plant foods. They hunted large Ice Age animals like the mammoth, mastodon, and large steppe bison, sometimes camping close to a kill while they butchered the carcass. Clovis artifacts have been found throughout North America and deep into Central America, with variants on this culture farther south.
A population boom
It appears that humans literally exploded into the New World, living off a fauna that was unused to such formidable predators. As a result, the human population rose rapidly, then stabilized, as people adapted to a great variety of natural environments, everything from rocky coasts to desert and dense rainforest. By 8800 B.C.E., most large late Ice Age animals except for the bison were extinct, probably as a result of rapid climate change and drought. Some experts believe that human predators helped in the process of extinction by exploiting slow-breeding mammals like the mammoth and mastodon. Whatever the cause of extinction, the disappearance of big game fostered greater cultural diversity among Paleo-Indian groups. They adapted to a rapidly changing world that was not to stabilize to nearmodern conditions until about 4000 B.C.E.