Mounting evidence from genome analysis of archaic populations has indicated that the various hominin species mated with each other.
When Neanderthal and modern human populations crossed paths, they interbred too. The Neanderthal genome data confirms that there was “leakage of DNA” from these extinct hominins into modern humans.
“Neanderthals live on a little bit in people living outside Africa today,” Pääbo said, making up about two percent of the genome of all humans that don’t originate from Africa.
Collating the genetic material of two related hominin species — the Neanderthals and Denisovans — and comparing it with sequence data of 25 humans, the researchers have triangulated in on a section of the hominin genome that is unique to our species.
“It’s a definitive recipe if you like for making a modern human,” Pääbo said. “We can now start doing experiments to ask what is it that makes modern humans special.”
“There is also an interesting question of what, if anything, Neanderthal and Denisovan DNA may be doing in the people that have it today, and whether it has been of benefit or detriment to our species,” Chris Stringer, a paleoanthropologist at the Natural History Museum in London, who was unconnected with the work, wrote in a comment sent to press.
Further research into what those areas coded for may reveal why we, homo sapiens, lived on while Denisovans, Neanderthals, and scores of our hominin relatives vanished.