The genetic similarities between certain human populations and Neanderthals are striking. Indeed, many researchers think the Europeans and Asians inherited between 1 and 4 percent of their DNA from Neanderthals, yet scientists have struggled to demonstrate with a high degree of certainty that these genetic similarities are the result of interbreeding between these two species. In the past, genetic similarities between Neanderthals and humans have been associated with two possible scenarios. The first hypothesis puts forth that idea that certain human populations — those that went on to become modern Eurasians — evolved in isolated patches in Africa that allowed them to stay genetically similar to Neanderthals after they split from their shared common ancestor.