10.1 Neanderthal and Denisovan introgression
As modern humans migrated out of Africa 50,000-70,000 years ago, they encountered and intebred with two groups of archaic hominins, the Neanderthals and Denisovans.
Admixture with archaic hominins resulted in introgression of archaic DNA into these migrating populations. These Neanderthal and Denisovan sequences still persist in the genomes of their present-day descendents.
Fig. 1. Ancient encounters between migrating human populations and archaic hominins.