Genetic History of the Human Species

Abstract

Abstract A major and continuing issue in anthropology is the recent evolutionary history of the human species. One question is the relationship of early humans ( Homo erectus ) to later larger‐brained hominids often referred to as ‘archaic humans’ and ‘anatomically modern humans’. The major debate is between the recent African origin model and the multiregional model. The recent African origin model proposes that Homo sapiens arose as a separate species in Africa within the past 200 000 years, and then dispersed across the Old World replacing non‐African archaic populations. The multiregional model suggests that human evolution over the past 2 million years has been within a single evolving polytypic species. Genetic data have been used increasingly to address these different models (and different variants of each). Several different approaches have been used: gene trees, genetic diversity within populations, genetic distances between populations, and reconstructions of ancient demography. Much of the genetic data is consistent with a replacement model. However, these data are also compatible with a general multiregional model that postulates genetic input from at least two geographic regions. To date, neither model is supported unequivocally by the genetic evidence. Genetic estimates of ancient population size favor an African origin model, but it is still not clear whether this rules out non‐African archaic genetic input. One possibility is that our species is mostly, but not exclusively, out of Africa.