[LINK] "Neanderthals Lived in Small, Isolated Populations, Gene Analysis Shows"

[rfmcdonald]

This analysis, reported by National Geographic News' Dan Vergino, is fascinating. The sample size is small--three Neanderthals and one Denisovan--but the preliminary conclusions are quite noteworthy. How were ancient humans different from each other? We're learning.

Compared to Neanderthals, humanity appears to have evolved more when it comes to genes related to behavior, suggests a team headed by Svante Pääbo, a pioneer in ancient genetics at Germany's Max Planck Institute for Evolutionary Anthropology. Their study was published today in the Proceedings of the National Academy of Sciences.

They note in particular that genes linked to hyperactivity and aggressive behavior in modern humans appear to be absent in Neanderthals. Also missing is DNA associated with syndromes such as autism.

"The paper describes some very interesting evolutionary dynamics," said paleoanthropologist John Hawks of the University of Wisconsin at Madison.

The Neanderthal genes suggest that sometime after one million to 500,000 years ago, Neanderthal numbers decreased and the population stayed small, Pääbo's group determined. A small population size would have been bad news for Neanderthals, Hawks said, because it would have meant that "natural selection had less power to weed out bad mutations."

Pääbo and colleagues looked at the genes of two ancient Neanderthals, one from Spain and one from Croatia. They compared the DNA of those individuals to that of a third Neanderthal who had lived in Siberia and whose DNA had been analyzed in an earlier study, and to the DNA of several modern humans.