Others added complexity: the Australasian signal in some South American populations, evidence of population replacements in some regions, evidence of deep divergences between North and South American populations that might reflect more complex founding scenarios than originally envisioned.

The Kennewick Man ancient genome, published in 2015, provided another critical data point.

The individual known as Kennewick Man — or Kennewick, or the Ancient One, depending on whose terminology one uses — had been at the center of a heated debate about whether his skull morphology indicated a relationship to ancient populations outside the Americas.

The genome resolved this debate clearly: Kennewick Man was most closely related to modern Native American populations, and specifically to the tribes that had claimed him as an ancestor and sought his repatriation.

The Anzick findings had already suggested this would be the result, given the consistency between the ancient genomes and modern Native American populations; the Kennewick genome confirmed it.