Scientists found genes inherited from Neanderthal relatives when they studied the genes of a man whose 45,000-year-old remains were found in Siberia.
Analysing the genes allowed the researchers to narrow down the date when humans and Neanderthals interbred to between 50,000 and 60,000 years ago.
The work, presented in the international journal Nature, provides insights into the early history of modern humans outside Africa.
Remains of a man found near the settlement of Ust’-Ishim in western Siberia are calculated to be around 45,000 years old and are believed to represent the oldest directly radiocarbon-dated modern human outside Africa and the Middle East.
Janet Kelso of the ax Planck Institute for Evolutionary Anthropology, Germany, and colleagues retrieved, sequenced and analysed the genome of this individual.
They found he carried a similar level of Neanderthal ancestry as present-day Eurasians.
Their analysis indicates Neanderthal gene flowed into the ancestors of the man 7,000 to 13,000 years before he lived.
Previous estimates of the timing of interbreeding between modern humans and Neanderthals range from 37,000 and 86,000 years ago.
However, this study suggests it occurred about 50,000 to 60,000 years ago, coinciding with the expansion of modern humans into Europe and possibly Asia.
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