Previously it had been thought that the modern humans and Neanderthals first admixed about 60,000 years ago, but traces of human DNA found in a Neanderthal genome suggest that modern humans started sleeping with our now-extinct relatives 100,000 years ago. The research documenting this new finding is published in the journal Nature.
The specimen they used for the basis of this study was a toe bone found Denisova cave in the Altai Mountains of southern Siberia. The researchers describe how they compared Neanderthal genomes with those from modern Africans who do not carry Neanderthal DNA. They found no trace of modern human DNA in Neanderthals from Spain or Croatia, but the Altai Neanderthal had strands of DNA that closely matched those of the modern Africans.
What this means is some Neanderthals came into contact with modern humans long before others did. Evidence has been mounting that early modern humans were living in the Levant and China over 120,000 years ago. This new study corroborates this finding, revealing that at least one group of modern humans made it all the way to the Altai mountains over 100,000 years ago, where they formed families with the local Neanderthals.