Genetic trace? in Papuan genomes suggests two expansions out of Africa

Several major studies, published today, concur that virtually all current global human populations stem from a single wave of expansion out of Africa. Yet one has found 2% of the genome in Papuan populations points to an earlier, separate dispersal event - and an extinct lineage that made it to the islands of Southeast Asia and Oceania. Papuans share for most part same evolutionary history as all other non-Africans, but our research shows they may also contain some remnants of a chapter that is also yet to be described. Luca Pagani A new study of human genomic diversity suggests there may have in fact been two successful dispersals out of Africa, and that a 'trace' of the earlier of these two expansion events has lingered in the genetics of modern Papuans. Three major genetic studies are published today in the same issue of Nature. All three agree that, for the most part, the genomes of contemporary non-African populations show signs of only one expansion of modern humans out of Africa: an event that took place sometime after 75,000 years ago. Two of the studies conclude that, if there were indeed earlier expansions of modern humans out of Africa, they have left little or no genetic trace.