A new analysis of DNA from ancient modern humans (Homo sapiens) in Europe and Asia has determined, more precisely than ever, the time period during which Neanderthals interbred with modern humans, starting about 50,500 years ago and lasting about 7,000 years — until Neanderthals began to disappear.
That interbreeding left Eurasians with many genes inherited from our Neanderthal ancestors, which in total make up between 1% and 2% of our genomes today.
A more precise timeline for modern human interactions with Neanderthals can help scientists understand when humans emigrated out of Africa and peopled the globe, while understanding the DNA that Neanderthals shared with our ancestors provides information on the role Neanderthal genes play in human health.
The genome-based estimate is consistent with archeological evidence that modern humans and Neanderthals lived side-by-side in Eurasia for between 6,000 and 7,000 years. The analysis, which involved present-day human genomes as well as 58 ancient genomes sequenced from DNA found in modern human bones from around Eurasia, found an average date for Neanderthal-Homo sapiens interbreeding of about 47,000 years ago. Previous estimates for the time of interbreeding ranged from 54,000 to 41,000 years ago. The new dates also imply that the initial migration of modern humans from Africa into Eurasia was basically over 43,500 years ago.
“The timing is really important because it has direct implications on our understanding of the timing of the out-of-Africa migration, as most non-Africans today inherit 1-2% ancestry from Neanderthals,” said Priya Moorjani, an assistant professor of molecular and cell biology at the University of California, Berkeley, and one of two senior authors of the study. “It also has implications for understanding the settlement of the regions outside Africa, which is typically done by looking at archeological materials or fossils in different regions of the world.”