Berlin: Modern humans and Neanderthals first interbred approximately 50,000 to 60,000 years ago, according to scientists who sequenced the genome of a man's thigh bone found in Siberia.
Researchers analysed the shaft of a man's thigh bone found by an artist and mammoth ivory collector, Nikolai Peristov, on the left bank of the river Irtysh near the settlement of Ust'-Ishim in western Siberia in 2008.
The study calculated the age of the man's bone to be about 45,000 years old.
"This is the earliest directly dated modern human outside of Africa and the Middle East, and the oldest modern human [genome] to have been sequenced," study co-author Janet Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, told 'Live Science'.
The scientists found that the man carried a similar level of Neanderthal ancestry as present-day Eurasians. Their research suggests Neanderthal genes flowed into the ancestors of this man 7,000 to 13,000 years before he lived.
These findings suggest modern humans and Neanderthals interbred approximately 50,000 to 60,000 years ago, "which is close to the time of the major expansion of modern humans out of Africa and the Middle East," Kelso said.
Analysis of the carbon and nitrogen isotopes in his bones suggest the man ate so-called C3 plants that dominate cooler, wetter, cloudier regions - examples of which include garlic, eggplants, pears, beans and wheat - as well as animals that also dined on C3 plants.
He may have eaten aquatic foods, probably freshwater fish, something seen in other humans from Europe of about the same time.
Previously, scientists had suggested modern humans colonised Asia first by travelling a more southern, coastal route that gave rise to the present-day people of Oceania, while a later, more northern migration, gave rise to mainland Asians.
The fact the researchers found direct evidence for the presence of a modern human in Siberia 45,000 years ago "indicates that early modern human migrations into Eurasia were not solely via a southern route as has been previously suggested," Kelso said.
The study was detailed in the journal Nature.