Neither Neandertal nor modern human
Genome of extinct Siberian hominin sheds new light on modern human origins
An international research team led by Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig has sequenced the nuclear genome of an at least 30,000-year-old human finger bone that was excavated in 2008 by archaeologists from the Russian Academy of Sciences in southern Siberia. According to analyses, this human from Denisova was neither Neandertal nor modern human, but a previously unknown hominin form. (Nature, December 23, 2010)
Earlier this year the team showed that the mitochondrial DNA from the finger bone displayed an unusual sequence, suggesting that it came from an as yet unknown ancient hominin form. Using techniques that the researchers developed to sequence the Neandertal genome, they have now sequenced the nuclear genome from the bone. The researchers found that the individual was female and comes from a group of hominins that shared an ancient origin with Neandertals, but subsequently had a distinct history. They call this group of hominins Denisovans. Unlike Neandertals, Denisovans did not contribute genes to all present-day Eurasians. However, Denisovans share an elevated number of genetic variants with modern-day Papuan New Guinean populations, suggesting that there was interbreeding between Denisovans and the ancestors of Melanesians.
In addition, a Denisovan tooth found in the same cave shows a morphology that is distinct from Neandertals and modern humans and resembles much older hominin forms. Bence Viola, a scientist at the Max Planck Institute for Evolutionary Anthropology comments: "The tooth is just amazing. It allows us to connect the morphological and genetic information".
David Reich, an Associate Professor at Harvard Medical School who led the population genetic analysis, says: "The fact that Denisovans were discovered in Southern Siberia but contributed genetic material to modern human populations from New Guinea suggests that Denisovans may have been widespread in Asia during the Late Pleistocene."
Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology remarks: "In combination with the Neandertal genome sequence, the Denisovan genome suggests a complex picture of genetic interactions between our ancestors and different ancient hominin groups".
This study also involved contributions from researchers at the Broad Institute of Harvard and MIT (Massachusetts, USA), the University of California both Santa Cruz and Berkeley (California, USA), the University of Tübingen (Germany), Emory University (Georgia, USA), the University of Montana (Montana, USA), the University of Washington (Washington, USA), the Institute of Evolutionary Biology (Barcelona, Spain), the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (Beijing, China), the University of British Columbia (Vancouver, Canada), and the Institute of Archaeology & Ethnography, Russian Academy of Sciences, Siberian Branch (Novosibirsk, Russia).
Financial support came from Max Planck Society, and the Krekeler Foundation (Germany), the National Institutes of Health (USA), and the National Science Foundation (USA).