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DNA change accounts for white skin

den4

先輩
15 Nov 2002
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ttp://www.washingtonpost.com/wp-dyn/content/article/2005/12/15/AR2005121501728_pf.html
(took the h out of http, so it isn't linked directly. replace the h to see the link. added entire story here, in case the link goes bye bye...)

Say what? U mean dat white boy he my brutha? No wunda so many folks be wantin' t' git a tan... :D

although they say not to put "race" into this finding, it will happen....it's human nature to do so :D

Scientists Find A DNA Change That Accounts For White Skin

By Rick Weiss
Washington Post Staff Writer
Friday, December 16, 2005; A01

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.

The discovery, described in today's issue of the journal Science, was an unexpected outgrowth of studies Cheng and his colleagues were conducting on inch-long zebra fish, which are popular research tools for geneticists and developmental biologists. Having identified a gene that, when mutated, interferes with its ability to make its characteristic black stripes, the team scanned human DNA databases to see if a similar gene resides in people.

To their surprise, they found virtually identical pigment-building genes in humans, chickens, dogs, cows and many others species, an indication of its biological value.

They got a bigger surprise when they looked in a new database comparing the genomes of four of the world's major racial groups. That showed that whites with northern and western European ancestry have a mutated version of the gene.

Skin color is a reflection of the amount and distribution of the pigment melanin, which in humans protects against damaging ultraviolet rays but in other species is also used for camouflage or other purposes. The mutation that deprives zebra fish of their stripes blocks the creation of a protein whose job is to move charged atoms across cell membranes, an obscure process that is crucial to the accumulation of melanin inside cells.

Humans of European descent, Cheng's team found, bear a slightly different mutation that hobbles the same protein with similar effect. The defect does not affect melanin deposition in other parts of the body, including the hair and eyes, whose tints are under the control of other genes.

A few genes have previously been associated with human pigment disorders -- most notably those that, when mutated, lead to albinism, an extreme form of pigment loss. But the newly found glitch is the first found to play a role in the formation of "normal" white skin. The Penn State team calculates that the gene, known as slc24a5, is responsible for about one-third of the pigment loss that made black skin white. A few other as-yet-unidentified mutated genes apparently account for the rest.

Although precise dating is impossible, several scientists speculated on the basis of its spread and variation that the mutation arose between 20,000 and 50,000 years ago. That would be consistent with research showing that a wave of ancestral humans migrated northward and eastward out of Africa about 50,000 years ago.

Unlike most mutations, this one quickly overwhelmed its ancestral version, at least in Europe, suggesting it had a real benefit. Many scientists suspect that benefit has to do with vitamin D, made in the body with the help of sunlight and critical to proper bone development.

Sun intensity is great enough in equatorial regions that the vitamin can still be made in dark-skinned people despite the ultraviolet shielding effects of melanin. In the north, where sunlight is less intense and cold weather demands that more clothing be worn, melanin's ultraviolet shielding became a liability, the thinking goes.

Today that solar requirement is largely irrelevant because many foods are supplemented with vitamin D.

Some scientists said they suspect that white skin's rapid rise to genetic dominance may also be the product of "sexual selection," a phenomenon of evolutionary biology in which almost any new and showy trait in a healthy individual can become highly prized by those seeking mates, perhaps because it provides evidence of genetic innovativeness.

Cheng and co-worker Victor A. Canfield said their discovery could have practical spinoffs. A gene so crucial to the buildup of melanin in the skin might be a good target for new drugs against melanoma, for example, a cancer of melanin cells in which slc24a5 works overtime.

But they and others agreed that, for better or worse, the finding's most immediate impact may be an escalating debate about the meaning of race.

Recent revelations that all people are more than 99.9 percent genetically identical has proved that race has almost no biological validity. Yet geneticists' claims that race is a phony construct have not rung true to many nonscientists -- and understandably so, said Vivian Ota Wang of the National Human Genome Research Institute in Bethesda.

"You may tell people that race isn't real and doesn't matter, but they can't catch a cab," Ota Wang said. "So unless we take that into account it makes us sound crazy."
© 2005 The Washington Post Company
 
Amazing how quickly this degenerated into race-baiting comments.

But the target is white people, so that's okay.
 
Well, everything I know about science came from watching Bill Nye, but that was a fascinating article. Speaking as an African-American, I'm all too willing be gracious and inclusive towards my lighter skinned bretheren....even if they are mutants! But then, I read X-Men, so being a mutant isn't all bad! Heh!

:D
 
Let's try to imagine the degree of tolerance if, instead of making light of the article by joking that white people are mutants, someone had instead offered the opinion that blacks are more primitive lifeforms.

How well would such a comment have gone over or been tolerated here?
 
The Part That Catches My Eye......

is the fact that science is slowly unraveling the DNA mystery. I hope it leads to cures to some of our worst medical problems in the future.

Frank

 
mikecash said:
Let's try to imagine the degree of tolerance if, instead of making light of the article by joking that white people are mutants, someone had instead offered the opinion that blacks are more primitive lifeforms.

I stand corrected. Perhaps we shouldn't "go there".
 
Well, I recall not too long ago some Japanese went and tanned themselves all dark so they be black....but I knew it wouldn't be long before "race" got entangled on this topic.... Let's Intolerance! :D
I wonder how long it'll be before the next skin color in fashion will be "yellow" ? :?

I go with Frank....rather than race, we need a cure for diseases :)
 
another media hype

Really not much new here. They found one gene that was partly (!) responsible for "white" skin & say that it's a mutation. So what? We knew all along that races (& other divisions) are created by mutation, & not only one single mutation but a whole range. The only news is that they found one (& only one) of the genes involved.


den4 said:
a finding that helps solve one of biology's most enduring mysteries and illuminates one of humanity's greatest sources of strife.
Mystery? In which world does the author live?

"Almost all the differences used to differentiate populations from around the world really are skin deep."
Crap. Skin colour is only a very minor (& not very decisive) factor in determining race biologically.

others have posited that its novelty and showiness simply made it more attractive to those seeking mates.
Whites being more attractive? Isn't this a bit racist? :p Anyway: novelty? For 50,000 years?

That showed that whites with northern and western European ancestry have a mutated version of the gene.
What about "whites" from India, they can have a fairly dark skin colour?

Scientists Find A DNA Change That Accounts For White Skin
[...]
The Penn State team calculates that the gene, known as slc24a5, is responsible for about one-third of the pigment loss that made black skin white. A few other as-yet-unidentified mutated genes apparently account for the rest.
One or more?

But they and others agreed that, for better or worse, the finding's most immediate impact may be an escalating debate about the meaning of race.
I wonder why "meaning" sneaks into such debates so often. Nature doesn't have a philosophical meaning. But maybe my understanding of "meaning" is limited.

"You may tell people that race isn't real and doesn't matter, but they can't catch a cab," Ota Wang said. "So unless we take that into account it makes us sound crazy."
Ah, yes. That was definitely needed to satisfy the US PC faction.



UFSI said:
white people are all mutants!!
mikecash said:
Amazing how quickly this degenerated into race-baiting comments.
Sorry, but I can't see what's so bad about being a mutant. We all are mutants, without mutation no evolution, without evolution no human beings.
 
bossel said:
Sorry, but I can't see what's so bad about being a mutant. We all are mutants, without mutation no evolution, without evolution no human beings.

That is a pretty simplistic view though, personally I have no problem with the word either.

To many though, the word mutant is an emotional one, and will engender negative feelings and reactions. This is why labelling someone a mutant is a dangerous thing, regardless of the scientific sensibilities behind the phrase.

I am sure you could think of a lot more words that are valid scientifically but unacceptable socially...
 
Gaijin 06 said:
That is a pretty simplistic view though, personally I have no problem with the word either.
Bossel's view might be simplistic, but it is factual.

I didn't take offence at the comment that 'white people are mutants', I found it funny. Good comedy often comes from the ability to laugh at yourself. UFSI made it blatantly obvious that he was having a bit of fun (exclamation mark, smileys), so I don't see the problem.
 
So....if I said blacks are unevolved primitive humans and included a smiley, that would be alright?
 
mikecash said:
So....if I said blacks are unevolved primitive humans and included a smiley, that would be alright?
Of course not. You obviously don't think it's funny, it's obvious to anyone that you're not being light-hearted. 'Mutant' is a word that has humorous, positive connotations in the popular consciousness, as Flashjeff pointed out due largely to X-Men. 'Unevolved primitive humans' does not have the same light-hearted connotations. In fact, 'primitive' usually has negative connotations - for example, it's a popular insult among some teenagers I know. Find a way of saying it that's actually funny and I might not have a problem with it. In the UK we have a show called Goodness Gracious Me that demonstrates well how this kind of humour can be funny.
 
But some people who sincerely believe repugnant racists ideas are also amused by jokes based upon them. That one is light-hearted and thinks what one says is funny is no reliable indicator as to the sincerity with which the comment is made.

I'm not attempting to be politically correct here, just trying to do my little bit to abolish the double standard that exists when it comes to race.

I also fail to see anything humorous or positive in "white people are all mutants!!", regardless of how light-heartedly the comment may have been offered. Maybe instead of "unevolved primitive humans" I should have used a phrase like "jungle bunny" to illustrate my point. After all, "bunny" is a cute word that makes people feel good. So if the first reply to the original post had be "he he he.........black people are all jungle bunnies!!" <smiley smiley smiley> then the obvious light-hearted nature of the comment and the cuteness of having "bunny" in there should preclude anyone taking offense at it. Or does that double standard thing rear its ugly head again?
 
The word 'bunny' might be cute, but the whole phrase 'jungle bunny' is clearly offensive, and that one cute word doesn't excuse it, IMO.

OK, here's another reason the original comment is funny. It's true. White people (and of course all creatures on this planet) really are mutants. Neither of your examples are true, which is probably another reason why they are offensive. Black people aren't unevolved or primitive, and neither do they live in jungles. If someone said those things it would expose not only their insensitivity, but also their ignorance. I don't think it can be a double standard, given at least two differences between the two sets of comments.

Incidentally, am I right in thinking you've disabled smilies? At the risk of taking his choice of smilies too seriously, the particular smilies that UFSI chose showed that he knew he was making a controversial comment, but he was doing it for the sake of humour.
 
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Of course neither of my examples are true. But the world has suffered through centuries of people who would have no trouble embracing them. Who have indeed justified their actions and policies by fervently expounding them. The same sort of people who would look at that report through the other end of the prism from the one that brings forth the pc-acceptable "whites are all mutants!!" and come up with something derogatory to those of darker skin which conveniently also serves to justify their own sense of genetic superiority. And they could say it with great mirth, glee, utter sincerity, and no end of smilies.

But would we as a group have tolerated such a post here on JREF Forums? Why are white people not allowed to take offense at comments that would be race-baiting were the target other than white people? And does standing silent while it happens not implicitly and tacitly accept the premise that whites are somehow superior?
 
It Is Rare........

for Den4 to post serious posts. Seems the thread was ment to be light hearted. Tis the season to be jolly as they say. Seems like a thread hijack to turn it into a lesson in politically correctness based on past attacks. If scientists came up with this stuff, it should be taken with a grain of sugar; next week another group will disprove and discredit it.

Uncle Frank

:eek:
 
I detest political correctness, Uncle Frank, but I detest double standards even more.
 
right, but all humans are mutant monkeys anyway, so WHO CARES? gives a bit of diversity to the world!
 
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