Hello, Mutants!
Where the white people come from, by Rick Weiss in The Washington Post:
Scientists said yesterday that they have discovered a tiny genetic mutation that largely explains the first appearance of white skin in humans tens of thousands of years ago, a finding that helps solve one of biology's most enduring mysteries and illuminates one of humanity's greatest sources of strife.The work suggests that the skin-whitening mutation occurred by chance in a single individual after the first human exodus from Africa, when all people were brown-skinned. That person's offspring apparently thrived as humans moved northward into what is now Europe, helping to give rise to the lightest of the world's races.
Leaders of the study, at Penn State University, warned against interpreting the finding as a discovery of "the race gene." Race is a vaguely defined biological, social and political concept, they noted, and skin color is only part of what race is -- and is not.
In fact, several scientists said, the new work shows just how small a biological difference is reflected by skin color. The newly found mutation involves a change of just one letter of DNA code out of the 3.1 billion letters in the human genome -- the complete instructions for making a human being.
"It's a major finding in a very sensitive area," said Stephen Oppenheimer, an expert in anthropological genetics at Oxford University, who was not involved in the work. "Almost all the differences used to differentiate populations from around the world really are skin deep."
The work raises a raft of new questions -- not least of which is why white skin caught on so thoroughly in northern climes once it arose. Some scientists suggest that lighter skin offered a strong survival advantage for people who migrated out of Africa by boosting their levels of bone-strengthening vitamin D; others have posited that its novelty and showiness simply made it more attractive to those seeking mates.
The work also reveals for the first time that Asians owe their relatively light skin to different mutations. That means that light skin arose independently at least twice in human evolution, in each case affecting populations with the facial and other traits that today are commonly regarded as the hallmarks of Caucasian and Asian races.
Several sociologists and others said they feared that such revelations might wrongly overshadow the prevailing finding of genetics over the past 10 years: that the number of DNA differences between races is tiny compared with the range of genetic diversity found within any single racial group.
Even study leader Keith Cheng said he was at first uncomfortable talking about the new work, fearing that the finding of such a clear genetic difference between people of African and European ancestries might reawaken discredited assertions of other purported inborn differences between races -- the most long-standing and inflammatory of those being intelligence.
"I think human beings are extremely insecure and look to visual cues of sameness to feel better, and people will do bad things to people who look different," Cheng said.
I think people are truly more divided by how much money they have or don't have than anything else. Accordingly, I heard Morgan Freeman talking in a 60 Minutes preview last night that he wants to do away with the terms "black" and "white" as ways of describing people. A lady from the NAACP came on saying something along the lines of "He's got enough money that he's no longer black; he's transcended being black."
Hmm. "Single individual"?
Conservationists are telling us repeatedly that a viable population requires quite a few more than that, although this isn't speciation.
It also isn't news.
I wonder why it is, though, that it forbidden to even breathe these differences in "polite" society. Note well that any time we talk about a creature other than Man, we say that the adaptation to the environment was natural and reinforced by circumstances.
Radwaste at December 17, 2005 4:47 PM
A mutation in a single individual is all it takes, if the conditions favour its survival. It will be inherited and would appear to be favoured with increasing latitude. If you don't start with just one gene in one individual, you'd need to have simultaneous identical mutations in how many individuals? I suppose that could come about as a result of, say, a viral infection; but where did the virus get the gene?
A detail I don't understand is how the presence or absence of a particular allele - which is all or nothing - produces a range of skin tones from very dark to very light. Can anyone explain?
Norman at December 18, 2005 6:10 AM
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