Thursday, March 25, 2010

New species of early human found in Siberia

25 March, 2010, 10:45

DNA from a 40-thousand-year-old bone found in a Siberian cave is believed to belong to a previously unknown hominin. The “Hominin-X” joins Neanderthals as a now-extinct evolutionary competitor of modern human.

The fossil finger bone was discovered in 2008 by a team of archaeologists led by Mikhail Shunkov and Anatoly Derevyanko of the Russian Academy of Sciences in Novosibirsk. It was found in the Denisova cave in the Altay Mountains in a layer radiocarbon dated to between 48,000 and 30,000 years ago.

Geneticists Svante Pääbo, Johannes Krause and their colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, sampled the fossil and sequenced DNA from mitochondria. The same team previously sequenced both Neanderthal and prehistoric modern human DNA.

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To their big surprise, DNA found in the Siberian bone did not resemble either, and differed from the genome of the modern human in almost twice as many nucleotide positions as the Neanderthal genome. The scientists believe that the Denisova hominin shares a common ancestor with Homo Sapiens sometime about 1 million years ago.

The lineage of our newly-discovered relative has so far been difficult to trace, and the team is not even giving it a name as yet, calling it Hominin X. They hope to find more clues about its origin after sequencing nuclear DNA from the bone.

The discovery of the new hominin is also interesting because it is the first find based solely on genome analysis and not on reconstruction from fossils.

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