Analysis of a fossilised tooth (pictured) and finger bone found in a Siberian cave reveals that they came from a recently discovered relative of humans that lived more than 30,000 years ago. DNA showed that this creature is more closely related to Neanderthals than to modern humans.
Credit: National Science Foundation
WASHINGTON: A previously unknown relative to the Neanderthal who lived in Asia 30,000 to 50,000 years ago and interbred with the ancestors of Papua New Guinea inhabitants has been discovered by an international team.
Scientists were able to extract the entire genome of the group known as the Denisovans using only a finger bone and a wisdom tooth found in Siberia's Denisova Cave in 2008.
An earlier mitochondrial genome sequence conducted in March provided little information about the hominid other than it was part of a population long diverged from humans and Neanderthals.
Denisovans and Melanesians interbreeding
The finger bone and tooth are now known to come from a female from the hominid group that shared its ancient origin with the Neanderthal but quickly diverged.
Unlike the Neanderthals, the Denisovans did not contribute to the genetic pool of modern Eurasians, but share up to one twentieth of their DNA with the inhabitants of Papua New Guinea and islands northeast of Australia.
This suggests there was interbreeding between the Denisovans and the ancestors of the Melanesians, the researchers said in a study published in Nature.
Not such a clean-cut story after all
"The story now gets a bit more complicated," said study co-author Richard Green, an assistant professor of biomolecular engineering in the Baskin School of Engineering at the University of California, Santa Cruz.
"Instead of the clean story we used to have of modern humans migrating out of Africa and replacing Neanderthals, we now see these very intertwined story lines with more players and more interactions than we knew of before."
The international research team was led by Svante Paabo of the Max-Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Neanderthals moved west, Denisovans east
Researchers believe the Neanderthals and Denisovans migrated from Africa around half a million years ago.
The Neanderthals moved westward settling in the Middle East and Europe, while the Denisovans traveled to the east and interbred with other humans some 50,000 years ago when they moved to the coasts of southern Asia.
David Reich, a Harvard Medical School geneticist who led the Denisova analysis, said the Denisovans may have migrated from Siberia toward Asia at the end of the Pleistocene Epoch, between 400,000 years ago to 50,000 years ago.
