The Southern Native American branch encompasses most of the Indigenous populations of Central and South America — again, hundreds of distinct nations speaking diverse languages, occupying environments from tropical rainforest to high-altitude Andean grassland, maintaining cultural traditions as varied as the environments they inhabit.

The Southern Native American branch shares with the Northern branch the basic Beringian founding ancestry, but it carries specific genetic variants that reflect an early divergence from the Northern Native American branch — a divergence that appears to have occurred relatively early in the history of the Americas, as populations spread southward from the founding region in Alaska.

The relationship between these two branches is most simply described as a single early split: the founding Beringian population differentiated into two major groups, one of which spread primarily through North America and one of which spread primarily through Central and South America.

The reality is more complex — there are mixed-ancestry populations in many parts of the Americas, and the specific patterns of gene flow and isolation that shaped the distributions of Northern and Southern Native American ancestry are still being worked out — but the two-branch framework captures the major structure that the genetic evidence reveals.