[LINK] "The Little Bit of Neanderthal in All of Us"

[rfmcdonald]

Carl Zimmer's New York Times article summarizing two recent studies on the degree and nature of Neanderthal ancestry in modern human beings is interesting, as much for its suggestions as to what Neanderthals did contribute as to what they didn't. They may have been more genetically distinctive than a mere isolated hominid population.

The first draft of the Neanderthal genome was too rough to allow scientists to draw further conclusions. But recently, researchers sequenced a far more accurate genome from a Neanderthal toe bone.

Scientists at Harvard Medical School and the Max Planck Institute for Evolutionary Anthropology in Germany compared this high-quality Neanderthal genome to the genomes of 1,004 living people. They were able to identify specific segments of Neanderthal DNA from each person’s genome.

“It’s a personal map of Neanderthal ancestry,” said David Reich of Harvard Medical School, who led the research team. He and his colleagues published their results in the journal Nature.

Living humans do not have a lot of Neanderthal DNA, Dr. Reich and his colleagues found, but some Neanderthal genes have become very common. That’s because, with natural selection, useful genes survive as species evolve. “What this proves is that these genes were helpful for non-Africans in adapting to the environment,” Dr. Reich said.

[. . .]

Both studies suggest that Neanderthal genes involved in skin and hair were favored by natural selection in humans. Today, they are very common in living non-Africans.

[. . .]

Both teams of scientists also found long stretches of the living human genomes where Neanderthal DNA was glaringly absent. This pattern could be produced if modern humans with certain Neanderthal genes could not have as many children on average as people without them. For example, living humans have very few genes from Neanderthals involved in making sperm. That suggests that male human-Neanderthal hybrids might have had lower fertility or were even sterile.

Overall, said Dr. Reich, “most of the Neanderthal genetic material was more bad than good.”

io9/u> and National Geographic go also have posts discussing the findings.