It seems no surprise that modern humans and Neanderthals interbred as most of the Eurasian population is, genetically, 1.6% to 2.1% Neanderthal. The question has long been when they did, with a wide estimate putting it between 37,000 and 86,000 years ago based on the DNA of people alive today. But the recent study revealed that modern humans and Neanderthals interbred around 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.
The researchers examined thigh bone of a Siberian man, discovered by Nikolai Peristov, an artist and mammoth ivory collector on the left bank of the river Irtysh near the settlement of Ust’-Ishim in western Siberia in 2008. The age of the man’s bone to be is about 45,000 years old, researchers stated.
Janet Kelso, co-author of the study and a computational biologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, told Live Science, “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.”
Formerly, the researchers had proposed modern humans firstly populated Asia by traveling towards southern, coastal route that gave rise to the present-day people of Oceania, while a later, more northern migration, gave rise to mainland Asians. Kelson stated, “the researchers’ evidence for the modern human presence in Siberia 45,000 years ago specifies that the early modern humans were not just migrated to Eurasia through a southern route as previously suggested.”
The genetic analysis of the bone revealed that the it is closely related to present-day Asians and to early Europeans. “From this we conclude that the population to which the Ust’-Ishim individual belonged diverged from the ancestors of present-day Europeans and Asians before, or at around the same time as, these groups diverged from one another,” Kelso said.
The researchers believed that 45,000 years old man carried a similar level of Neanderthal ancestry as present-day Eurasians and the Neanderthal genes moved into the ancestors of this man 7,000 to 13,000 years before he lived.