Since the 1930s, it’s been a generally accepted theory that indigenous Americans are descendants of Siberians who came to the New World by crossing a land bridge into Alaska around 15,000 years ago.

But, the details of that migration remain a source of contention. Did the Asians who trekked across the Bering Strait arrive in one or several waves? Were some of them isolated from the rest, settling on the land bridge until it submerged beneath the water of melting glaciers?

Two new studies—relying on genetic data from living individuals and ancient skeletons—offer possible answers, albeit with different interpretations.

The first research paper, published this week in Nature, suggests that there were two founding populations. The investigating scientists, led by