Final answer:
Genetic evidence reveals that modern humans interbred with Neanderthals and Denisovans, as seen in the DNA of modern populations. This gene flow signifies a common history of interbreeding among various hominin species. Discoveries of first-generation hybrids and Denisovan DNA in modern humans further support this theory.
Step-by-step explanation:
Genetic data has provided substantial evidence indicating that modern humans interbred with earlier hominins such as Neanderthals and Denisovans. Recovery of DNA from fossilized bones has revealed that there are similarities between the DNA of Neanderthals and modern European-derived populations. In addition, genetic research has unveiled the existence of a first-generation hybrid individual, Denisova 11, who had a Denisovan father and a Neanderthal mother. This finding, along with others, supports the notion that interbreeding was a common occurrence when these groups met.
Modern European and Middle Eastern populations contain about 1 to 4 percent Neanderthal DNA, and studies have suggested that additional DNA may derive from unknown archaic hominins, referred to as 'ghost populations.' For example, indications that West African populations may have inherited DNA from an unrecognized archaic hominin species. Moreover, the presence of Denisovan DNA in modern humans providing further evidence of gene flow between Homo sapiens and other hominins like the Denisovans, who are closely related to Neanderthals.
These discoveries provide a new perspective on human evolution, suggesting not only a genetic but also a cultural exchange between the different hominin populations. The implications of such interbreeding are far-reaching and continue to inform our understanding of human history and genetics.