Deep inside an underwater cave in Mexico, archaeologists may have discovered the oldest human skeleton ever found in the Americas.Early Native Americans seem to have had higher diversity in appearance than later ones, but this does not really indicate waves of migration from different sources. See Craniofacial shape variation and Native American origins
Dubbed Eva de Naharon, or Eve of Naharon, the female skeleton has been dated at 13,600 years old. If that age is accurate, the skeleton—along with three others found in underwater caves along the Caribbean coast of the Yucatán Peninsula—could provide new clues to how the Americas were first populated.
Clues from the skeletons' skulls hint that the people may not be of northern Asian descent, which would contradict the dominant theory of New World settlement. That theory holds that ancient humans first came to North America from northern Asia via a now submerged land bridge across the Bering Sea (see an interactive map of ancient human migration).
"The shape of the skulls has led us to believe that Eva and the others have more of an affinity with people from South Asia than North Asia," González explained.
This model takes into account a founder population occupying Beringia during the last glaciation characterized by high craniofacial diversity, founder mtDNA and Y-chromosome lineages and some private autosomal alleles. After a Beringian population expansion, which could have occurred concomitant with their entry into America, more recent circumarctic gene flow would have enabled the dispersion of northeast Asian-derived characters and some particular genetic lineages from East Asia to America and vice versa.This is not specific to the Americas: the familiar traits of the three major human races (Caucasoids, Mongoloids, and Negroids) were in existence for a long time before their first attestation. It is a process of diversity-reducing selection, and integration of traits of different origins that has led to the crystallization of the present-day types during the Holocene.