GENETICS OF MODERN HUMAN ORIGINS AND DIVERSITY

A major and continuing debate in anthropology concerns the question of whether modern Homo sapiens emerged as a separate species roughly 200,000 years ago in Africa (recent African origin model) or as the consequence of evolution within a polytypic species spread across several regions of the Old World (multiregional model). Genetic data have been used to address this debate, focusing on the analysis of gene trees, genetic diversity within populations, and genetic differences between populations. Although the genetic data do provide support for the recent African origin model, they also are compatible with the multiregional model. The genetic evidence provides little direct inference regarding phylogeny, but it can tell us a great deal about ancient demography. Currently, neither model of modern human origins is unequivocally supported to the exclusion of the other.