The recent discovery of an ancient human femur bone is now helping scientists unpack mysteries of our past, including when humans interbred with our extinct relatives, the Neanderthals.
Found along the Irtysh river near the settlement of Ust’-Ishim in western Siberia, the thighbone contained well-preserved DNA that was used to reconstruct the genome of a 45,000-year-old modern human. This is the oldest modern human genome ever.
This find is so important because analysis of the genome showed that the man’s DNA contained 2% Neanderthal DNA – a similar percentage to the DNA composition of people from Asia and Europe today.
Working backwards, scientists found out that this means that interbreeding between Neanderthals and modern humans must have taken place at least 45,000 years ago. Using additional clues and data, such as the length of strands of DNA, the team concluded that that humans and Neanderthals had reproductive sex around 50,000 to 60,000 years ago.
Before these findings were published in the journal Nature this week, the scientific community had a wide range of estimates for when this interbreeding took place – anywhere from 37,000 to 86,000 years ago.
“What we think may be the case is that the ancestors of the Ust’-Ishim man met and interbred with Neanderthals during the initial early admixture event that is shared by all non-Africans at between 50,000 and 60,000 years ago, and perhaps somewhere in the middle East,” Janet Kelso, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, told the Guardian.