"The study allows us to conclusively reject an alternate theory that
humans and Neanderthals evolved from the same sub-population,"
scientists said.
The new genome analysis also indicates that modern Europeans and Asians inherited more Neanderthal DNA than previously thought.
"Our
approach can distinguish between two subtly different scenarios that
could explain the genetic similarities shared by Neandertals and modern
humans from Europe and Asia," explained Konrad Lohse, a population
geneticist at the University of Edinburgh.
In the study,
researchers used a different kind of genetic testing they had previously
developed with rare species of European insects and Southeast Asian
pigs.
They compared the genome of a Neanderthal, a European human, an African human, and a chimpanzee.
"The method makes maximum use of the information contained in individual genomes," Lohse added.
"Our
analysis allows us to conclusively reject a model of ancestral
structure in Africa and instead reveals strong support for Neanderthal
admixture in Eurasia at a higher rate (3.4 percent-7.3 percent) than
suggested previously," said co-author Laurent AF Frantz of the
Wageningen University in The Netherlands.
According to Mark
Johnston, editor of the journal Genetics that published the study, "This
work is important because it closes a hole in the argument about
whether Neanderthals interbred with humans".
The method can be
applied to understanding the evolutionary history of other organisms,
including endangered species, he concluded.
In December last year, geneticists sequenced the most complete Neanderthal genome yet.
Neanderthals
are genetically distinct enough from modern humans to earn them their
own species designation, Homo neanderthalensis.
They lived among
Homo sapiens in Europe, the Middle East, and central Asia as recently as
28,000 years ago before either going extinct or being incorporated into
the modern human species.
