There is evidence for interbreeding between archaic and modern humans during the Middle Paleolithic and early Upper Paleolithic.
The interbreeding happened in several independent events that included Neanderthals, Denisovans, as well as several unidentified hominins respectively.
In Eurasia, interbreeding between Neanderthals and Denisovans 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. Neanderthal-derived and Denisovan-derived ancestry is significantly absent from most modern populations in Sub-Saharan Africa, but archaic alleles consistent with several independent admixture events in the subcontinent have been found.
In Eurasians, the highest rates of archaic admixture overall 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. In certain West African populations, admixture rates appear to be significantly higher than in Eurasians, with an estimated admixture at 13% from a "basal western African" lineage in Mende people found for instance.
Although the narratives of human evolution are often contentious, DNA evidence shows that human evolution should not be seen as a simple linear or branched progression, but a mix of related species. In fact, genomic research has shown that hybridization between substantially diverged lineages is the rule, not the exception, in human evolution. Furthermore, it is argued that hybridization was an essential driving force in the emergence of modern humans.