What is needed, specifically, is ancient DNA from northeastern Asian and Beringian populations from the relevant periods — roughly 20,000 to 30,000 years ago — that would allow researchers to directly characterize the genetic diversity of the populations that eventually gave rise to Native Americans.

Collecting such data is extremely challenging: the relevant sites are largely under water (because sea level rise flooded much of the Beringian landscape after the end of the last Ice Age) or in remote and archaeologically difficult locations, and DNA preservation in the cold but wet conditions of much of the relevant region is variable.

Some ancient DNA data from northeastern Asia is available, and it has contributed important evidence to the debate.

Ancient genomes from Siberian populations dating to the relevant period show complex genetic histories that include components related to both East Asian and more western Eurasian populations, with different ancient Siberian individuals showing different proportions.