Svante Pääbo studies the bone belonging to the Ust'-Ishim man (Credit: Bence Viola, MPI EVA)

According to "Nature," biologists have managed to derive DNA from the 45,000-year-old skeletal remains of the Ust'-Ishim man; Ultimately allowing them to establish a firm timetable for human and Neanderthal interbreeding. Originally, we suspected that this took place between 37,000 to 86,000 years ago. Now, that number has dwindled down to 50 thousand years.

Insight into Neanderthal and human sexual relations took a sharp turn for the better back in 2010, when scientists were able to decode the genome from Neanderthal DNA. Upon closer inspection, we learned that, not only was interbreeding successful in many instances, but that the evidence still lurks  in our own genome in the present day.

Tracing Our Roots:

Eurasian-dwelling Neanderthals — those that lived in Europe and Asia, their natural stomping grounds — started dying out tens of thousands of years back, with the creatures becoming extinct about 40,000 years ago (a full 10,000 years sooner than we originally thought). However, the close ancestors that would eventually evolve into modern-day humans did manage to survive (otherwise, we wouldn't be talking about this right now), their fate cemented by the fact that they began breeding with Neanderthals, which, in turn, appears to coincide with their migration out of Africa. Even now, approximately 1.5 to 2.1 % of the DNA of any human from outside of Africa can be traced back to Neanderthals.

Artist rendering of a neanderthal compared to a modern human (via Softpedia)

However, up until now, this information still didn't tell us exactly when interbreeding became commonplace. It took an unlikely discovery made by an ivory collector, named Nikolai Peristov, for that. Back in 2008, Peristov discovered a femur (the shaft of a thighbone) in western Siberia, which has since been dated 45,000 years back. Yes, this small, anciently old bone found on accident helped answer a question that has been a source of contention ever since Darwin presented his once-controversial theory of evolution.

Lessons From The Ust'-Ishim Man:

What's more is that it has revised history too. Before this, we believed that modern-day humans originated from Africa, migrated to Asia, before venturing south and following a coastal route. After which, they headed north, which "gave rise to mainland Asians." Contrarily, the study's author — Janet Kelso, of the Max Planck Institute for Evolutionary Anthropology — notes that the evidence of modern-day humans living in Siberia during this period of time  "indicates that early modern human migrations into Eurasia were not solely via a southern route as has been previously suggested."

To expand:

Moving forward, hopefully we will be able to sequence even more genomes from much older remains. Kelso notes that they are also interested in determining "what functional implications the Neanderthal DNA in present-day people might have had in the adaptation of present-day humans to their new environments."

The findings are set to be published in the Oct. 23 issue of  'Nature.'

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