Before they were Native Americans, were they Beringians?

-> Before they were Native Americans, were they Beringians?
When -- and how -- did the ancestors of Native Americans become genetically distinct from Asians who crossed the Bering land bridge into Alaska and the rest of North America?

For one thing, that Bering-crossing population would have had to remain isolated from other Asian populations for many millenniums, scientists say. Now, a research team led by Dennis O'Rourke of the University of Utah is theorizing that the land of Beringia, now largely submerged beneath northern seas, had the climate and plant resources to sustain wildlife and feed a human population for thousands of years.