Interbreeding between archaic and modern humans

Interbreeding between archaic humans (such as Neanderthals and Denisovans) and anatomically modern humans (contemporaneous Homo sapiens) took place during the Middle Paleolithic and early Upper Paleolithic. It has been revealed via genomic sequencing that all modern human populations outside of Africa today carry approximately 1–4% Neanderthal DNA, which is a result of genetic admixture that occurred after modern humans migrated out of Africa.

Source: Wikipedia — Interbreeding between archaic and modern humans (CC BY-SA 4.0)