Paleo-Indians, Paleoindians or Paleo-Americans were the first humans who entered, and subsequently inhabited, the Americas during the final glacial episodes of the late Pleistocene period. The prefix paleo- comes from the Greek adjective palaios (παλαιός) 'old; ancient'. The term Paleo-Indians applies specifically to the lithic period in the Western Hemisphere and is distinct from the term Paleolithic.
Traditional theories suggest that big-animal hunters crossed the Bering Strait from North Asia into the Americas over a land bridge (Beringia). This bridge existed from 45,000 to 12,000 BCE (47,000–14,000 BP). Small isolated groups of hunter-gatherers migrated alongside herds of large herbivores far into Alaska. From c. 16,500 – c. 13,500 BCE (c. 18,500 – c. 15,500 BP), ice-free corridors developed along the Pacific coast and valleys of North America. This allowed animals, followed by humans, to migrate south into the interior of the continent. The people went on foot or used boats along the coastline. The precise dates and routes of the peopling of the Americas remain subjects of ongoing debate. At least two morphologically different Paleo-Indian populations were coexisting in different geographical areas of Mexico 10,000 years ago.
Stone tools, particularly projectile points and scrapers, are the primary evidence of the earliest human activity in the Americas. Archeologists and anthropologists use surviving crafted lithic flaked tools to classify cultural periods. Scientific evidence links Indigenous Americans to eastern Siberian populations. Indigenous peoples of the Americas have been linked to Siberian populations by the distribution of blood types, and genetic composition as indicated by molecular data, such as DNA. There is evidence for at least two separate migrations. From 8000 to 7000 BCE (10,000–9,000 BP) the climate stabilized, leading to a rise in population and lithic technology advances, resulting in a more sedentary lifestyle.
Migration into the Americas[]
Further information on theories of Paleo-Indian migration to and throughout the Americas: Settlement of the Americas Map of early human migrations based on the Out of Africa theory; figures are in thousands of years ago (kya) Researchers continue to study and discuss the specifics of Paleo-Indian migration to and throughout the Americas, including the exact dates and routes traveled. The traditional theory holds that these early migrants moved into Beringia between eastern Siberia and present-day Alaska 17,000 years ago, at a time when the Quaternary glaciation significantly lowered sea levels. These people are believed to have followed herds of now-extinct pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets. An alternative proposed scenario involves migration - either on foot or using boats - down the Pacific coast to South America. Evidence of the latter would have been submerged by a sea-level rise of more than a hundred meters following the end of the last glacial period.
The time range of the peopling of the Americas remains a source of substantial debate. Conventional estimates have it that humans reached North America at some point between 15,000 and 20,000 years ago. The few areas of agreement achieved to date are the origin from Central Asia, with widespread habitation of the Americas during the end of the last glacial period, or more specifically what is known as the late glacial maximum, around 16,000–13,000 years before present.