The Americas are the newest chapter in this global story, and the ancient genome evidence from the Americas is, relative to what exists for Europe and parts of Asia, still in its early stages.

The Population Y debate is one part of this emerging picture — a finding that suggests the ancestral diversity of Native American populations reflects the complex population history of Asia during the period before the American dispersal, carrying the signature of ancient movements and contacts that preceded the founding of the Americas by thousands of years.

In this global context, the Population Y signal is not anomalous.

It is exactly the kind of finding that the genomic revolution has repeatedly produced in other parts of the world — evidence that the populations of any given region carry traces of ancient people and ancient movements that simple models of population history do not capture.