So what did these “experts” have to say? Actually it was two experts — one who refused to give his name and another of uncertain expertise. But more on that later.

“I think the reason for light skin and red hair is that we do not get enough sun and we have to get all the Vitamin D we can,” Alistair Moffat, managing director of ScotlandsDNA, told the Independent. “If the climate is changing and it is to become more cloudy or less cloudy then this will affect the gene. If it was to get less cloudy and there was more sun, then yes, there would be fewer people carrying the gene.”

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As John Upton at the Grist points out, the argument is based on several flawed assumptions.

A single gene mutation codes for red hair and fair skin.

Not so, says Rick Potts, a paleoanthropologist who leads the Smithsonian’s Human Origins Program. “Although geneticists tend to discover individual genes that play a role in hair color and texture, often many genes play a role,” Potts told the Grist. “So the matter may not be as simple as the decrease in a single recessive gene.”

Gene mutation evolved to help Europeans soak up more sun, which is needed to produce more vitamin D in cloudy environments.

Scientists at the University of California at San Francisco recently published research that cast doubt upon that idea. One of the researchers, Peter M. Elias, said the hypothesis was “flawed for many reasons” and “recent studies show that dark-skinned humans make vitamin D after sun exposure as efficiently as lightly-pigmented humans.”

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As the climate changes, the world will see fewer clouds.

Upton points out there is “considerable debate” among climate scientists about the role of global warming in cloud formation.

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As the clouds disappear, so too will the genes that helped humans adapt to cloudy environments — and the redheads who carry those genes.

Finally, Upton notes, modern humans don’t face the same evolutionary pressures as our ancestors. Redheads have sunscreen and Vitamin D supplements to combat the threat the sun allegedly poses to their existence.

Who is this Alistair Moffat anyway?

ScotlandsDNA is one of those Web sites that claims to trace your ancestry if you send them a DNA sample. On the site, he lists his credentials: MA (Hons), M.Phil, Cert.Ed. but doesn’t say anything about a background in genetics. Nevertheless, he writes books on the subject, including “The British: A Genetic Journey” and “The Scots: A Genetic Journey.” You can find out about his other writing, mostly histories of Scotland, on his Web site.