Neanderthals that have been extinct for 28,000 years live on in human DNA, according to research suggesting the genes may help us better survive cold weather and be linked to some present-day diseases.

The Neanderthal genes make up only about 2 percent to 4 percent of the DNA carried by a given human today, according to a paper published in the journal Science. Even so, it may be linked to the development of our hair and skin, as well as to immune disorders such as Type 2 diabetes, the research found.

New DNA techniques are reshaping knowledge of human evolution just as quickly as theyre sparking the development of medical tests and treatments. Thats allowing scientists to peek into history by comparing modern DNA with the Neanderthal genome, recently reconstructed by scientists using material from the toe bone of a female who lived 50,000 years ago.

Were not as beholden to ancient DNA anymore, said Joshua Akey, an associate professor of genome science at the University of Washington in Seattle, and an author of one of the studies. Rather than excavating bones, we can now excavate DNA from modern individuals.

Akeys study identified the skin and hair traits. A second report yesterday by scientists at Harvard Medical School in Boston and the Broad Institute in Cambridge, Massachusetts, found nine links between Neanderthal DNA and previously identified human genes, some of which affect immune function.

The Neanderthal DNA found in the ancient toe bone was reported in the journal Nature in December. That study suggested inbreeding may have been common for Neanderthals, and may have led to their demise. Earlier studies using less complete genetic profiles determined that Neanderthals probably mated with ancient humans as well.

The latest DNA research supports that conclusion and suggests the Neanderthal genes left behind as a result may have aided humans in adapting to non-African environments, Akey said, adding, Whats striking is you can really look at the distribution of Neanderthal DNA across the entire genome.

Both studies published yesterday identified significant areas within the human genome where no Neanderthal genes appear, more than would be anticipated by chance. That suggests some mutations werent passed on, probably because they didnt help survival.

The shared genes that influence hair and skin traits also influence other things, Akey said. Its possible, for instance, that the Neanderthal genes helped alter pigmentation and moisture retention in humans, helping to increase body warmth in colder climates.

The Harvard study found that genes that are most active in the testes and those in the X chromosome have the least Neanderthal influence, compared to other parts of the genome. The pattern may have been a way for the body to naturally overcome infertility among different species.

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Neanderthal Genes Found in Modern Human DNA, Studies Find