Red Hair a Part of Neanderthal Genetic Profile

Oct 25, 08:20 PM

Current Headlines: PHILADELPHIA _ In an unprecedented feat of forensic anthropology, European researchers extracted enough DNA from two Neanderthal skulls to suggest their owners sported red hair and white skin back when they were alive 43,000 and 50,000 years ago.

The hair color of humanity's closest relative might sound trivial but the finding, announced in Friday's issue of the journal Science, stunned anthropologists with the sheer power of genetics to reveal what Neanderthals really looked like, and how they behaved. And that, some say, will change the way humanity views itself.

"We are building an image of these Neanderthal people _ their physical aspects, cognitive abilities, metabolism, immunity _ the range is enormous," said Carles Lalueza-Fox of Barcelona, an author of the paper.

Last week, the same team announced that Neanderthals and today's humans share a gene associated with language.

Until now, our understanding of Neanderthals was limited mostly to bone structure and artifacts. We knew they used stone tools, were stockier than we are and had prominent brow ridges.

Only in the last several years has genetics technology advanced enough to read the much-degraded DNA lodged in Neanderthal bone cells.

"My feeling is this will revolutionize the study of human origins," said Harold Dibble, a curator at the University of Pennsylvania Museum of Archaeology and Anthropology.

Scientists found the first Neanderthal fossils 150 years ago in Germany's Neander Valley. Since then, enough fossils surfaced to show their lineage branched off from ours about 500,000 years ago, in Africa. It's a relatively recent split compared to the one our lineage made from the chimpanzees' line around 6 million years back.

Both human and Neanderthal lineages continued to evolve bigger brains after parting ways. The Neanderthals left behind stone tools, and they almost certainly used fire, but they went extinct about 17,000 years ago, after a considerable overlap without own species.

Anthropologists generally consider Neanderthals to be human _ a member of the human family that may or may not have interbred with our ancestors.

But in the late 20th century the field split over just how similar Neanderthals were to us, said Dibble. He calls the two factions the "smart Neanderthal camp" and the "dumb Neanderthal camp".

The "dumb" camp says Neanderthals were significantly less intelligent than modern man despite a comparable brain size. They lacked language and complex social order and couldn't possibly have interbred with our ancestors.

The "smart" Neanderthal camp says they had comparable intelligence to us, they talked, and otherwise behaved like human beings.

To get past that impasse, a group of scientists led by Svante Paabo of the Max Planck Institute of Evolutionary Anthropology in Germany started attempting to sequence Neanderthal DNA _ a venture many regarded as a long shot.

Most Neanderthal bones are badly contaminated with bacteria and human DNA, so the researchers used fresh samples retrieved with gloves, masks and other precautions, said Lalueza-Fox.

Neanderthal DNA is likely to be 99.5 percent identical to ours, the experts say. In contrast, chimpanzee DNA is about a 96 percent to 98 percent match.

Lalueza-Fox said the team decided to focus on a skin pigment gene, called MC1R, because it was related to one known difference between Neanderthal and modern human history: Neanderthals left for Europe and the Middle East some 400,000 years ago while our ancestors stayed in Africa until about 50,000 years ago.

In Africa, there's huge evolutionary pressure to retain a certain version of this gene that promotes dark pigment, he said. Anyone with a genetic mistake that interfered with that would be left vulnerable to sunburn and skin cancer.

But in Europe, variations of this pigment gene can thrive and even flourish, since light-skinned people more efficiently produce vitamin D in relatively northern regions. One variant of the gene, for example, is common among Irish people and leads to red hair and pale, freckled skin.

Lalueza-Fox and colleagues found a different variant of the same gene in their Neanderthal samples.

But how do they know this new variant led to red-haired, white Neanderthals? Both the Neanderthal and modern versions hold the recipe for a similarly disabled version of a protein, said Hopi Hoekstra, an evolutionary geneticist at Harvard University.

Scientists were able to artificially reproduce the Neanderthal version of this protein in the lab, she said, thus demonstrating that it worked the same way as the one found in some modern redheads.

Another mutation in the MD1R gene turned up in wooly mammoth DNA, she said, suggesting that mammoths may have been blonde.

To make sure they weren't accidentally studying their own DNA, the researchers screened 3,700 people, including themselves, to bolster their case that this was not just a rare human genetic variant but a uniquely Neanderthal one.

"It's like a proof of concept," said Penns' Dibble. The finding bolsters the case that scientists really can sequence the DNA from Neanderthal bones, thus shedding light on dozens of other traits.

One of the traits that most fascinates scientists and the public alike is language. Last week, the same group touched on the big speech question by showing Neanderthals share with us a specific version of a gene called FOXP2, which has been associated with language.

They published that finding in the journal Current Biology.

We humans appear to carry a unique version of this gene, different from those found in other animals, including chimps. A few years ago, geneticists found that people with a mutation in the FOXP2 gene suffered from a language deficit. Some speculated that FOXP2 therefore played a key role in endowing humanity with the capacity to create complex languages.

But the Neanderthal DNA shows they too shared the human version of this gene. The researchers don't claim this as evidence Neanderthals talked, since we don't know exactly how FOX2P contributes to our language capacity or what other genes are involved.

But the newfound ability to compare our genes to those of our extinct relatives could offer powerful new clues to Neanderthal language and much else as well, said Lalueza-Fox. "Our conception of ourselves will be completely different."

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