Genomes of ancient North Americans reveal that Californian, Central and South American populations descend from an admixture of two parallel, terminal Pleistocene lineages.. Human genomes from ancient North Americans.

Previous genomic studies have supported a model in which all Native Central and South Americans descend solely from a Clovis-related source population (the southern branch), while Native North Americans derive most of their genetic ancestry from a source population that split from Clovis before ~15 kya (the northern branch) and the rest from additional, later gene flow from Siberia. Analyses of 91 ancient North American genomes, dating to 4.8-0.2 thousand years ago (kya), show that ancient northern branch populations lack the more recent Siberian component found in northern branch populations today and that southern branch populations derive a significant portion of their ancestry from the ancient northern branch, not just the southern as previously thought. Shifts on the west coast of North America in the proportions of these two ancestries are consistent with an initial coastal migration followed by outward expansions of populations from inside the continent.