Neanderthals and modern humans met and interbred long ago, an event detailed in 45,000 year-old DNA. Discovery of genetic code from 450 centuries in the past could help researchers map treks taken by our distant ancestors. This is the oldest DNA ever recovered from the bones of a genetically-modern human.
Around 45,000 years ago, a man died near the banks of the Irtyush River, near the settlement of Ust'-Ishim in what is now western Siberia. His femur was discovered accidentally in 2008 by archaeologists.
Collagen within the bone was processed in order to extract DNA from the Ice Age human.
Neanderthals, a subspecies of Homo sapiens, are the closest genetic match to human beings of all extinct species. They lived during the Pleistocene Epoch, between 200,000 and 30,000 years ago. Populations were spread around large areas of Europe and western Asia. The popular image of the species portrays them as primitive, uncivilized proto-humans. Modern research reveals Neanderthals buried their dead, used tools and were able to control fire.
Neanderthals were, on average, slightly shorter than modern humans, with females averaging five feet tall, about five inches shorter than males. Their noses were wider than modern humans, cheekbones were more angled and brow ridges more pronounced. Recent research shows genetic diversity among the species was not as great as Homo sapiens. Their disappearance remains one of the great mysteries in human evolution.
Previous research has shown Neanderthals and genetically-modern humans interbred long ago. Humans in the modern age still possess some genetic code from our distant Neanderthal cousins - between one and four percent. Among most people, this contribution is dependent on ethnicity, so some populations have a larger average percentage of Neanderthal genetic codes than others. Modern Africans are the only population which does not exhibit Neanderthal code within their DNA.
About two percent of the DNA found in the Ust'-Ishim human were shared with Neanderthals, about the same amount as in modern Europeans. However, these chains were longer than those seen in present-day populations.
"This allowed us to estimate that the ancestors of the Ust'-Ishim individual mixed with Neanderthals approximately 7,000-13,000 years before this individual lived or about 50,000 to 60,000 years ago, which is close to the time of the major expansion of modern humans out of Africa and the Middle East," Janet Kelso, head of computer-based analysis for the research team, said.
Study of the ancient DNA could help shed light on how early humans migrated out of Europe and eastern Asia, into the Middle East, as well as southern and southeast Asia.
Discovery of the ancient femur and analysis of the genetic code contained within the artifact was profiled in the journal Nature.