Genetically speaking, many humans populations aren't all that different from their evolutionary forerunners, the Neanderthals. Evolutionary biologists have known this. Scientists have even estimated that European and Asian people inherited anywhere from 1 to 4 percent of their DNA from Neanderthals.
But questions remained about how it happened. Did some early Homo Sapiens -- just separated from their closest relatives, the Neanderthals -- evolve in isolated pockets of Africa before branching out across the globe? Or did some early humans interbreed with Neanderthal populations?
Now researchers have confirmed that the latter is the most likely scenario, statistically speaking.
"We did a bunch of math to compute the likelihood of two different scenarios," study co-author Laurent Frantz told The Verge. Frantz is an evolutionary biologist at Wageningen University in the Netherlands.
"Our analysis shows that a model that involves interbreeding is much more likely than a model where there was sustained substructure in Africa," he added.
The study, which Frantz produced with his colleague Konrad Lohse, was published this week in the journal Genetics.
Many evolutionary theorists had previously supposed that Neanderthals and other early hominids lost out to humans via violence and/or competitive disadvantages. But this new study suggests that early human evolution was more complicated.
"Some think that we outcompeted [other hominids] or that they were killed by humans, but now we can see that it's not that simple," explained Frantz. He says it's likely early humans recruited some Neanderthals into their population -- not just for a one-night stand, but as a part of the group, living and sharing in daily activities.
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