Topic: Denisovan Genome decoded.

[Nemesis]

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Now Pääbo and his colleagues have devised a new method of genetic analysis that allowed them to reconstruct the entire Denisovan genome with nearly all of the genome sequenced approximately 30 times over akin to what we can do for modern humans. Within this genome, researchers have found clues into not only this group of mysterious hominins, but also our own evolutionary past. Denisovans appear to have been more closely related to Neandertals than to humans, but the evidence also suggests that Denisovans and humans interbred. The new analysis also suggests new ways that early humans may have spread across the globe. The findings were published online August 30 in Science

The new research reveals that the Denisovans had low genetic diversity—just 26 to 33 percent of the genetic diversity of contemporary European or Asian populations. And for the Denisovans, the population on the whole seems to have been very small for hundreds of thousands of years, with relatively little genetic diversity throughout their history.

Why were modern humans so successful whereas Denisovans (and Neandertals) went extinct? Pääbo and his co-authors could not resist looking into the genetic factors that might be at work. Some of the key differences, they note, center around brain development and synaptic connectivity. "It makes sense that what pops up is connectivity in the brain," Pääbo noted. Neandertals had a similar brain size–to-body ratio as we do, so rather than cranial capacity, it might have been underlying neurological differences that could explain why we flourished while they died out, he said.