May 24, 2005

The Peopling of the Americas

A new paper in PLoS Biology estimates the effective population size and time depth of Native Americans, using data on their genetic variation in several gene loci. Usual controversies in the subject of Native American origin revolve around the time of their first arrival, and whether there was a single or multiple Out-of-Asia movements into the Americas. This new paper, supports the idea that the Native Americans are a relatively recent offshoot of the Asian population.

This new research may explain many of the features of the Native Americans, who are undoubtedly Mongoloid, but often differ from Asiatic Mongoloids in having a much reduced frequency of the epicanthic fold, often prominent noses, and yet the familiar facial flatness and "Sinodont" dental pattern. Their appearance could easily be explained if they are descended from a Proto-Mongoloid population of small size, and hence did not partake in the subsequent evolution in Asia, which led to the formation of the complete Mongoloid racial complex.

PLoS Biology Volume 3 | Issue 6 | JUNE 2005

On the Number of New World Founders: A Population Genetic Portrait of the Peopling of the Americas

Jody Hey

The founding of New World populations by Asian peoples is the focus of considerable archaeological and genetic research, and there persist important questions on when and how these events occurred. Genetic data offer great potential for the study of human population history, but there are significant challenges in discerning distinct demographic processes. A new method for the study of diverging populations was applied to questions on the founding and history of Amerind-speaking Native American populations. The model permits estimation of founding population sizes, changes in population size, time of population formation, and gene flow. Analyses of data from nine loci are consistent with the general portrait that has emerged from archaeological and other kinds of evidence. The estimated effective size of the founding population for the New World is fewer than 80 individuals, approximately 1% of the effective size of the estimated ancestral Asian population. By adding a splitting parameter to population divergence models it becomes possible to develop detailed portraits of human demographic history. Analyses of Asian and New World data support a model of a recent founding of the New World by a population of quite small effective size.


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