One of the most striking findings was the pattern of genetic similarity between ancient individuals from geographically distant locations at roughly similar time periods.

The Spirit Cave Man, from Nevada approximately 10,600 years ago, showed genetic affinities with ancient individuals from the Lagoa Santa region of Brazil who lived at roughly the same time — despite being separated by many thousands of miles.

This similarity was not expected under models that assumed slow, gradual diffusion of people southward through the Americas.

It suggested instead that the initial spread of people across the hemisphere had been rapid — fast enough that populations at opposite ends of the continents had not yet had time to diverge significantly from each other.

This pattern — sometimes described as an “out of Beringia” model of rapid southward spread — has important implications for how we understand both the archaeology and the ecology of the first Americans.