Scientists have isolated the oldest DNA ever retrieved from a Homo sapiens bone (which was discovered by chance on the banks of a west Siberian river), a feat that helps explain the modern human’s colonization of our planet.  The femur, which was located in 2008, belonged to a man who is believed to have died around 45,000 years ago, scientists said.

In their announcement on Wednesday, the team of researchers explained that the genome they had retrieved contained traces from Neanderthals (the cousin species living alongside the Homo sapiens in Eurasia before mysteriously disappearing). In fact, there is research that shows that Homo sapiens and Neanderthals interbred for a period, causing around 2 percent of humans today to have a tiny Neanderthal imprint (except for Africans).

This discovery is not only unique in itself, it also brings important information to the “Out of Africa” scenario. The theory suggests that Homo sapiens evolved around 200,000 years ago in East Africa and migrated out of the continent. Researchers’ efforts to date when the Homo sapiens and Neanderthals interbred would indicate the moment when Homo sapiens began a key phase of this trek (leaving Eurasia for Southeast Asia).

This new study was published in the journal Nature and was coordinated by Svante Paabo, a renowned geneticist with the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Svante Paabo has also pioneered significant other research projects into Neanderthals.

The bone in question was found at the Irtyush River, near Ust’-Ishim and carries, as researchers noted, a bit more Neanderthal DNA than the non-African population living today. Additionally, the Neanderthal DNA found in this bone is found in relatively long strips as opposed to the Neanderthal DNA in our genome today, which is cut up and dispersed as a result of countless generations of reproduction.

Paabo’s team used this information as a clue for a “molecular calendar” of sorts, which helps date DNA according to its mutations over time. As such, the research team estimate that Neanderthals and Homo sapiens interbred anywhere between 7,000 to 13,000 years before the Siberian individual lived (around 60,000 years ago).

In a comment on the study, Chris Stringer, a professor at Britain’s Natural History Museum, said that this provides a rough date for Homo sapien’s migration into South Asia.

“The ancestors of Australasians, with their similar input of Neanderthal DNA to Eurasians, must have been part of a late, rather than early, dispersal through Neanderthal territory. While it is still possible that modern humans did traverse southern Asia before 60,000 years ago, those groups could not have made a significant contribution to the surviving modern populations outside of Africa, which contain evidence of interbreeding with Neanderthals.”

Stringer said.