As scientists peer further back in time and uncover evolutionary relationships in unprecedented detail, their findings are complicating the narrative of human history and rescuing some formerly missing chapters from obscurity.
[Quantitative biologist Adam] Siepel and his team found that around 3% of Neanderthal DNA — and possibly as much as 6% — came from modern humans who mated with the Neanderthals more than 200,000 years ago. The same group who gave rise to modern humans throughout the world also furnished Neanderthals with (at least a little) more DNA than the Neanderthals would later give them. “You think you’re just looking at a Neanderthal,” Siepel said, “but you’re actually looking at a mixture of Neanderthal and modern human.”
Were ancient hominins any better or worse off for carrying more genes from modern ones? So far, his team has found no evidence for either positive or negative selection in the flow of genes from modern humans into Neanderthals 200,000 years ago, which indicates that “most of this gene flow … is just a signature of populations in contact,” according to [paleoanthropologist John] Hawks.
“It suggests that maybe Neanderthals actually are us,” he said. “As different as they are, maybe they’re just another version of us.”
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