Instead, it's likely that they just share a smidgeon of DNA from a common primate ancestor.
Ancient humans may not have interbred with Neanderthals, after all
But what if the consensus is wrong? What if those genetic remnants were inherited not from Neanderthals, but from a common ancestor, an evolutionary forebear to both humans and Neanderthals? A newly published study by researchers at the University of Cambridge suggests it's possible.
In a study recounted in the latest issue of Proceedings of the National Academy of Sciences, a team of researchers led by evolutionary biologist Andrea Manica used computer models to simulate the last 500,000 years of population dynamics in Europe and Africa, under the assumption that there were two major migrations out of Africa. In the first migration, the common ancestor to modern humans and Neanderthals spread throughout Africa and Europe. In the process, their vast geographic distribution gave rise to genetic heterogeneity, not only between the continents, but within them, as well.
The model then posits that between 300 and 350 thousand years ago, the European populations became separated from the African ones. Those populations in the European range evolved into Neanderthals, the African populations into anatomically modern humans. Crucially, however, genetic heterogeneity within each continent was maintained. As a result, modern human populations in northern Africa may have retained chunks of their ancestral DNA that those in the southern reaches of the continent did not, genetic information that they shared with the recently evolved Neanderthals of Europe. When the second migration from Africa took place between 60,000 and 70,000 years ago, these northernmost African populations would have carried these genetic remnants into Europe with them; while those populations lacking the ancestral code remained in Africa.