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Complete Denisovan genome offers glimpse of ancient variation

Posted on behalf of Katherine Rowland.

From the fragment of a finger bone found in a Siberian cave, researchers have created the most accurate genetic map yet of an extinct human relative that, before 2010, was not known to exist.

Thanks to innovations in gene-sequencing technology, molecular geneticist Svante Pääbo and his colleagues at the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, and his colleagues have improved their genetic picture of the Denisovans, mapping every position of the genome 30 times over, with an unprecedented level of resolution. “Now we can look at variation,” says Pääbo. “We have a complete catalogue of what makes a fully modern human.”

Yesterday, the researchers released the complete DNA sequence online, with the hopes that the scientific community will start to answer some of the many questions raised by the discovery of this mysterious hominid.

Named after the cave in which the fragment was found (pictured), the Denisovans — pronounced dun-EE-suh-vinz — inhabited Asia at least 30,000 years ago, leaving behind no more than a tiny piece of finger and a wisdom tooth.

But from those scant remains, researchers have been able to map the entire genome. In 2010, the Leipzig team presented their first-draft genome, suggesting that the Denisovans are distinct from the Neanderthals and early modern humans in Eurasia (see ‘Fossil genome reveals ancestral link‘).

But where the preliminary sequence raised a host of questions, the newly released data may begin to provide some answers about who the Denisovans were. The improved resolution allows researchers to spot the differences between gene copies inherited from the mother and from the father.

Richard Edward Green, a biomolecular engineer at the University of California, Santa Cruz, who led the original gene sequencing, says that the new information provides a window into the population genetics of this species. “It’s pretty powerful,” he says of the technologies that transform a fingertip into an evolutionary record. “Every spot on the genome has a unique evolutionary history, and we can now draw comparisons and identify where there were common ancestors.”

Image © MPI for Evolutionary Anthropology


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