Asian and American mtDNA Evolution
version 2002 Feb 18
Peter Forster, Antonio Torroni, Colin Renfrew, Arne Röhl
The McDonald Institute for Archaeological Research
University of Cambridge, Cambridge
Dipartimento di Genetica e Microbiologia, Università di Pavia, Pavia
Mathematisches Seminar, Universität Hamburg, Hamburg

We reanalysed published mitochondrial DNA variation (mtDNA) of 826 east Asians and Papuans to date periods of significant colonisation and demographic increase. Living human mtDNA variants, which are maternally inherited, are related by an evolutionary tree, the ancestral nodes of which can be reconstructed and dated assuming a molecular clock. Our analysis dates the out-of-Africa migration of the ancestral mtDNA types that founded all Eurasian (including Papuan) lineages at 54000 years. While the proto-Papuan mtDNA continued expanding at this time along a southern route to Papua New Guinea, the proto-Eurasian mtDNA appears to have drifted genetically and does not show any comparable demographic expansion until 30000 years ago. By this time the east Asian, Indian, and European mtDNA pools seem to have separated from each other, as postulated by the weak Garden of Eden model. The east Asian expansion entered America about 25000 years ago and gave rise to the well-publicised five major mtDNA types which are found in all Amerind-speaking areas today. During the Last Glacial Maximum around 20000 years ago, northerly latitudes were depopulated on both sides of the Pacific, coinciding with a chronological gap in our expansion dates. Repopulation of northern Asian and American latitudes occurred after the Last Glacial Maximum, obscuring the ancestral Siberian gene pool of the first Americans, and, on the American side, giving rise to the ancestral mtDNA types of current Na Dene and Eskimo-Aleut speakers.