Archaic human admixture with modern humans
There have been several instances of archaic human admixture with modern humans through interbreeding of modern humans with Neanderthals, Denisovans, and/or possibly other archaic humans over the course of human history. Neanderthal-derived DNA accounts for an estimated 1–4% of the Eurasian genome, but it is significantly absent or uncommon in the genome of most Sub-Saharan African people. In Oceanian and Southeast Asian populations, there is a relative increase of Denisovan-derived DNA. An estimated 4–6% of the Melanesian genome is derived from Denisovans. Recent noncomparative DNA analyses—as no specimens have been discovered—suggest that African populations have a genetic contribution from a now-extinct archaic African hominin population. Nevertheless, there still are some doubts about the recent admixture events among a number of researchers. Ancient subpopulation structure ancestral to modern humans, Neanderthals, Denisovans, and other possible archaic humans has been proposed as an alternative explanation for the observed genetic similarities.