Archaic admixture

There is evidence for interbreeding (admixture) between archaic humans and anatomically modern humans during the Middle Paleolithic and early Upper Paleolithic.

In Eurasia, interbreeding between Neanderthals and Denisovans (both assumed to be derived from Eurasian Homo heidelbergensis) with modern humans took place several times between about 100,000 and 40,000 years ago, both before and after the recent out-of-Africa migration 70,000 years ago. Neanderthal-derived DNA was found in the genome of contemporary populations in Europe and Asia, estimated as accounting for between 1% and 6% of modern genomes. The highest rates of archaic admixture have been found in indigenous Oceanian and Southeast Asian populations, with an estimated 4%–6% of the genome of modern Melanesians being derived from Denisovans.

Neanderthal-derived ancestry is significantly absent from most modern populations in Sub-Saharan Africa. However, archaic alleles consistent with several independent admixture events in the subcontinent have been found.

Through whole-genome sequencing of three Vindija Neanderthals, a draft sequence of the Neanderthal genome was published by a team of researchers led by Richard Green on 7 May 2010 in the journal Science and revealed that Neanderthals shared more alleles with Eurasian populations (e.g. French, Han Chinese, and Papua New Guinean) than with Sub-Saharan African populations (e.g. Yoruba and San). According to Green et al. (2010), the observed excess of genetic similarity is best explained by recent gene flow from Neanderthals to modern humans after the migration out of Africa. Green et al. (2010) estimated the proportion of Neanderthal-derived ancestry to be 1–4% of the Eurasian genome. The proportion was estimated to be 1.5–2.1% in Prüfer et al. (2013), but it was later revised to a higher 1.8–2.6% by in Prüfer et al. (2017). The same study noted that East Asians carry more Neandertal DNA (2.3–2.6%) than Western Eurasians (1.8–2.4%) Lohse and Frantz (2014) infer an even higher rate of 3.4–7.3%.

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