The ancestors of Native Americans are proposed to have inhabited the Bering land bridge (Beringia) for as long as 10,000 years in a Feb. 28, 2014, article in the journal Science based on research by University of Utah anthropologist Dennis O'Rourke, archaeologist John Hoffecker of the University of Colorado at Boulder, and Scott Elias, a paleoecologist at the University of London.
The researchers base their conclusions on ice core evidence taken from the Bering Sea and along the Alaskan coast that contain pollen from trees and shrubs. The results are supported by 25,000 years of geological evidence from the time frame of the movement of glaciers in the area where the first Asians came to the Americas.
The scientists propose that there were habitable regions in Beringia that provided plant and animal food for the first Asians that ventured onto the Bering land bridge. The first Americans are proposed to have moved between the pockets of refuge until the glaciers melted enough to allow them to reach Alaska and spread across the Americas.
The first Native Americans were a mixture of Russian and Chinese people. The 10,000 years these people spent on the Bering land bridge may have provided the necessary interbreeding that produced Native Americans.