Neither Neanderthal nor sapiens: new human relative IDed

[nsane.forums]

At a press conference yesterday, researchers announced the completely unexpected: a Siberian cave has yielded evidence of an entirely unknown human relative that appears to have shared Asia with both modern humans and Neanderthals less than 50,000 years ago. The find comes courtesy of a single bone from individual's hand. Lest you think that paleontologists are overinterpreting a tiny fragment, it wasn't the shape of the bone that indicates the presence of a new species—it was the DNA that it contained.

The paper that describes the finding comes courtesy of the Max Planck Institute's Svante Pääbo, who has been actively pursuing the sequencing of the Neanderthal genome. It seems likely that this particular bone fragment was targeted due to suspicions that it might also provide an additional Neanderthal sequence. The site, called Denisova, is in the Altai Mountains of southern Siberia, an area that has had hominins present as early as 125,000 years ago. The sample itself came from a layer of material that dates from between 30,000 and 50,000 years ago. Neanderthal DNA was found in a sample from the same time period less than 100km away, while artifacts indicate that modern humans were also present in the region by 40,000 years ago.

So, there was no apparent reason to suspect that the bone would yield anything more than a familiar sequence. And in fact, most of the first half of the paper simply describes the methods used to construct a complete sequence of the mitochondrial DNA, including over 150-fold coverage of the genome, and an alignment program designed to account for the errors typical of ancient DNA sequences. About the only surprise here is that Pääbo's group has switched from using 454 sequencing machines to those made by Illumina.

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