University of Washington - Department of Statistics
The amount of genetic diversity established and maintained in a population is a function of its demographic history. For most species, there is no information on the long-term history, but for humans there is both substantial historical information and extensive genetic data on current individuals. Studies of Amerindian populations of Central and South America have revealed interesting patterns of presence and absence of genetic polymorphisms of global distribution and also of "Private Polymorphisms," the name given to genetic variants that have achieved substantial frequency in a tribal population or group of tribes, but not found elsewhere.
Analysis shows that much of the observed variation postdates tribal differentiation and incipient agriculture; very few extant variants are likely to have arisen in the long prehistory of Amerindian colonization. More generally, it is found that historical information alone cannot give precise predictions of genetic variation, and that history cannot be inferred from genetic data, but that the two together provide a clearer understanding of the forces that have shaped current patterns of genetic diversity.