Just as we are trying to digest the implications of the draft Neandertal genome (which, by the way, suggests that Neandertals contributed up to 4% of their genomes to non-African modern human populations), a new study published in Nature by David Reich (Harvard Med School) and colleagues reports the genome of an unclassified (all we have is a pinky bone and an isolated tooth) ca. 40,000-year-old hominin from Denisova Cave in southern Siberia. The genome appears distinct both from that of European Neandertals and contemporary modern humans. However, there is evidence that early modern human populations interbred with these “Denisovans” and, in fact, modern Melanesian populations (represented in the paper by genomes from Papua New Guinea and Bougainville) appear to have received approximately 4% of their genomes from this extinct group of humans.
So, taken together, these genetic data seem to indicate that modern Melanesians derive up to 8% of their genomes (4% Neandertal and 4% “Denisovan”) from now-extinct human groups. Pretty cool stuff.
UPDATE 12.23.11. Dr. Hawks is also interviewed in an NPR story from Dec. 23 that summarizes the implications of these data.