Abstract: With the emergence and advancements in ancient DNA experimental methods and high-throughput sequencing technology, it is increasingly possible to directly extract and retrieve genetic materials from ancient human fossils. This has led to a series of breakthroughs in the genomic research of archaic humans, including reconstructing the past interactions between archaic humans (i.e. Neanderthals and Denisovans) and modern humans outside Africa. Fossil and ancient DNA evidences indicate that as the early modern humans spread from Africa, they encountered and received genes from archaic humans after some coexistence with them; likewise, the genes of early modern humans affected certain archaic populations, and that the archaic populations had genetic admixture among themselves. Interbreeding among prehistoric humans occurred many times across geography, and has laid down the foundation of the gene pool of modern humans. It is profoundly influencing the way we think about our physiology and morphology as well as the prevalence of diseases in present-day.

Key words: Neanderthals; Denisovans; Early modern humans; Interbreeding; Ancient DNA; High-throughput DNA sequencing technologies