Resolving the question will require ancient genomes from Beringia and northeastern Asia in the period 20,000 to 40,000 years ago — genomes that would directly characterize the ancestral diversity of the populations that eventually founded the Americas.

Collecting such data faces significant practical challenges, both archaeological and genetic, but it is not impossible, and the ongoing development of ancient DNA methods continues to extend the range of what can be recovered.

In the meantime, the Population Y question serves as a reminder that the story of how the Americas were peopled is not a simple story, and that the genomic revolution in human prehistory research is revealing complexity rather than simplicity at every level of analysis.

The ancient people of Lagoa Santa were Native Americans, the descendants of the founding population that crossed Beringia into the Americas.