Early modern human dispersal from Africa: genomic evidence for multiple waves of migration

• DOI: 10.1186/s13323-015-0030-2
• Publication Date: 2015-11-06T12:02:46Z
• Authors: Francesca Tassi; Silvia Ghirotto; Massimo Mezzavilla; Sibelle Torres Vi...; Lisa De Santi; Guido Barbujani
• Keywords: 0301 basic medicine; 0303 health sciences; 03 medical and health sciences; Research; Admixture; Evolutionary divergence; Human demographic history; Linkage disequilibrium; Migration; Population structure; Human demographic history, Migration, Evolutionary divergence, Admixture, Linkage disequilibrium, Population structure

AbstractBackgroundAnthropological and genetic data agree in indicating the African continent as the main place of origin for modern human. However, it is unclear whether early modern humans left Africa through a single, major process, dispersing simultaneously over Asia and Europe, or in two main waves, first through the Arab peninsula into Southern Asia and Oceania, and later through a Northern route crossing the Levant.ResultsHere we show that accurate genomic estimates of the divergence times between European and African populations are more recent than those between Australo-Melanesia and Africa, and incompatible with the effects of a single dispersal. This difference cannot possibly be accounted for by the effects of hybridization with archaic human forms in Australo-Melanesia. Furthermore, in several populations of Asia we found evidence for relatively recent genetic admixture events, which could have obscured the signatures of the earliest processes.ConclusionsWe conclude that the hypothesis of a single major human dispersal from Africa appears hardly compatible with the observed historical and geographical patterns of genome diversity, and that Australo-Melanesian populations seem still to retain a genomic signature of a more ancient divergence from Africa