This diversity is consistent with the idea that the ancestral Native American population was itself genetically diverse in ways that could produce descendant populations with different affinities to different parts of the Old World.

But the specific ancient data needed to definitively test the deep ancestral structure model — Beringian genomes from the period just before the American dispersal — are not yet available.

This means that the Population Y debate cannot currently be resolved by direct evidence from the relevant ancestral populations, and that the competing models must be evaluated on the basis of their consistency with the available evidence rather than by direct test.

The Geography of the Signal