The Out of Africa hypothesis and the ancestry of recent humans: Cherchez la femme (et l'homme)

The Out of Africa hypothesis (OOAH) has been a mainstay in the discussion of human evolution since its presentation in the 1980's. However, recent advances in palaeontology and molecular genetics have made it possible to examine the hypothesis in a manner that was inconceivable at the time of its proposal. The palaeontological progress relates to early Homo finds in the Caucasus, Denisova finds in the Altai Mountains and Neanderthal finds in a wide range of localities from the Altai Mountains, the Caucasus, the Levant, Asia Minor, southern and Central Europe and the Iberian Peninsula. The Eurasian location of these finds and recognition of the principle of Last common ancestor (LCA) lend no support to OOAH. The same conclusion is drawn from genomic findings, which (a) have revealed the presence of Denisovan and Neanderthal nuclear DNA, primarily in the genomes of recent Eurasians and (b) have shown genomic introgression from early modern humans into Neanderthals in the Altai Mountains. Similarly, archaeological finds in Sulawesi and the discovery of approximate to 100,000 years old human teeth in southern China constitute strong independent challenges to OOAH. The genomic and palaeogenomic results and the new palaeontological and archaeological discoveries suggest (a) that the ancestors of modern humans had their origin in a Eurasian (largely Asian) biogeographic region which may also have extended into NE Africa, and (b) that the founders of basal African lineages became separated, geographically and genetically, in the westernmost part of this region and spread from there to different parts of the African continent. (C) 2016 Elsevier B.V. All rights reserved.