section_path: Homo sapiens/Last Glacial Maximum/Americas
section_name: Americas
paragraph_text: Americas
  
  Paleo-Indians originated from Central Asia, crossing the Beringia land bridge between eastern Siberia and present-day Alaska. Humans lived throughout the Americas by the end of the last glacial period, or more specifically what is known as the late glacial maximum. Details of Paleo-Indian migration to and throughout the American continent, including the dates and the routes traveled, are subject to ongoing research and discussion.
  
  Conventional estimates have it that humans reached North America at some point between 15,000 and 20,000 years ago. The traditional theory is that these early migrants moved when sea levels were significantly lowered due to the Quaternary glaciation, following herds of now-extinct pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets. Another route proposed is that, either on foot or using primitive boats, they migrated down the Pacific coast to South America as far as Chile. Any archaeological evidence of coastal occupation during the last Ice Age would now have been covered by the sea level rise, up to a hundred metres since then. The recent finding of indigenous Australasian genetic markers in Amazonia supports that a coastal route and subsequent isolation did occur with some migrants.