The DNA of a 45000 year old bone of a Siberian man has been recently examined by the researchers to find out when human and Neanderthals first interbred. On record, this is an oldest genome sequence of Homo sapiens exposing a mysterious population that may once have spanned northern Asia. The study is published in the Nature journal.

The oldest human genome also revealed that the closest extinct relatives of the modern humans were the Neanderthals who lived in Europe and Asia and vanished around 40,000 years ago. The Neanderthals interbred with ancestors of modern humans when modern humans began spreading out of Africa and today 1.5 to 2.1 percent of the DNA of anyone living outside Africa is Neanderthal in origin, study reveals.

“It remains vague when interbreeding between Neanderthals and modern humans happened. But it probably ranged between 37000 to 86000 years ago,” researchers stated.

The researchers examined the bone (human left femur), 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 researchers further examined the carbon and nitrogen isotopes present in the man’s bone proposes that he ate C3 plants, which rule cooler, wetter, cloudier regions such as garlic, eggplants, pears, beans and wheat as well as animals that also dined on C3 plants. Though, the study analysis reveals that he might have eaten aquatic foods like fresh water fish.

The DNA analysis of mans’s bone revealed that the he was 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.

The results of the study propose 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,” Kelso added.