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Washington, May 7 (ANI): There’s a Neanderthal in all of us, as according to a study, some of our ancestors interbred with the thick-browed cavemen.

Boffins have produced the first whole genome sequence of the 3 billion letters in the Neanderthal genome, and the initial analysis suggests that up to 2 percent of the DNA in the genome of present-day humans outside of Africa originated in Neanderthals or in Neanderthals’ ancestors.

The international research team, which includes researchers from the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health, reports its findings in the May 7, 2010, issue of Science.

The current fossil record suggests that Neanderthals, or Homo neanderthalensis, diverged from the primate line that led to present-day humans, or Homo sapiens, some 400,000 years ago in Africa.

Neanderthals migrated north into Eurasia, where they became a geographically isolated group that evolved independently from the line that became modern humans in Africa. They lived in Europe and western Asia, as far east as southern Siberia and as far south as the Middle East.

Approximately 30,000 years ago, Neanderthals disappeared. That makes them the most recent, extinct relative of modern humans, as both Neanderthals and humans share a common ancestor from about 800,000 years ago.

In the study, the researchers compared DNA samples from the bones of three female Neanderthals who lived some 40,000 years ago in Europe to samples from five present-day humans from China, France, Papua New Guinea, southern Africa and western Africa. This provided the first genome-wide look at the similarities and differences of the closest evolutionary relative to humans, and maybe even identifying, for the first time, genetic variations that gave rise to modern humans.

“This sequencing project is a technological tour de force,” said NHGRI Director Eric D. Green, M.D., Ph.D. “You must appreciate that this international team has produced a draft sequence of a genome that existed 400 centuries ago. Their analysis shows the power of comparative genomics and brings new insights to our understanding of human evolution.”

The Neanderthal DNA was removed from bones discovered at Vindija Cave in Croatia and prepared in the clean room facility of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, to prevent contamination with contemporary DNA.

To understand the genomic differences between present-day humans and Neanderthals, the researchers compared subtle differences in the Neanderthal genome to the genomes found in DNA from the five people, as well as to chimpanzee DNA. An analysis of the genetic variation showed that Neanderthal DNA is 99.7 percent identical to present-day human DNA, and 98.8 percent identical to chimpanzee DNA. Present-day human DNA is also 98.8 percent identical to chimpanzee.

The comparison between Neanderthal and present-day human genomes has produced a catalog of genetic differences that allow the researchers to identify features that are unique to present-day humans. (ANI)