mutation found that accounts for white skin

Rick Weiss, a staff writer at the Washington Post, recently wrote an article titled Scientists Find A DNA Change That Accounts For White Skin. Here's the beginning of the article. If it interests, you follow the link to read the whole thing.

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.


I find this article interesting for two reasons. First it illustrates just how little change in our DNA is required for a big difference in our appearance. In case you want the technical language for that, genotype is the DNA sequence and phenotype is what we look like.

In the case of this study, published today in Science, a change of only one nucleic acid in a total of over 3 billion helps cause a change in skin color. They figure this one mutation accounts for about a third of the color difference between the original phenotype and the "European white" phenotype.

The second thing I find amazing about the article is how badly it skews the study. The reporter really doesn't get some of the science and makes some really silly "politically correct" statements as a result. For example:

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.


He emphasizes how genetics doesn't really matter and that across the races there's 99.9% correspondence of genotype (homology). That strikes me as missing the point since the article is showing how much of a change one nucleic acid makes. That 0.1% difference across the various groups of people equals over 3 MILLION nucleic acid changes in our DNA. Imagine how much difference that can make!

I think he'd have done better to emphasize how much simpler genetic coding is in phenotypical areas such as the color of skin, eyes, hair et cetera versus the much more complicated coding involved in intelligence or behavior.

This tendency for journalists to create news out of routine scientific papers is worrisome to me. Often the results being reported in the science journals are "tarted up" by the media and become controversial as a result. Most scientists don't encourage media attention and can get caught blindsided when obscure papers are sensationalized by reporters that usually don't understand the experimental results in the first place.

On the other hand, there are scientists that court media exposure--often as a way to receive greater notice and more funding. The mind springs quickly to the Korean scientist, Hwang Woo-suk, and the cloning controversy he's mired in.

In any case, the article that started me down this line of thought is a good illustration of how one successful mutation can change history. Our species originated in Africa where having dark skin was needed to protect us against ultraviolet light. This resulted in a lower efficiency in producing vitamin K but with plenty of sunlight available, that didn't matter.

Once some of our ancestors left Africa for some sightseeing in Europe and Asia this dark skin became an issue. Not having enough vitamin K results in weak bones and improper blood clotting. Having light skin would allow more vitamin K to be produced but wouldn't protect against high exposure to the sun.

This light skin mutation probably occurred a number of times in Africa but there it would be harmful and the child would have probably died of excessive sunburn. But once the location is changed to Europe with it's northern latitude and cloudy skies--skin fit with location. Hello ski vacations! Please excuse me if I make light of this. Ha-ha. Anyway, once the location fit the mutation the child survived and prospered which allowed the mutated gene to spread throughout the population over time. Ta-da.

Comments

Nukapai said…
Ah, now first, I was intrigued and entertained by your excellent post... until I saw... a SQUIRREL! DIE! DIE!

Ahem.
Juggling Mother said…
Oh what a sensible take on evolution!

The mutation probably happened lots of times, but only became dominant when the environment changed.

If only everyone could understand that simple explanation we might not have so many problems in the world.

I regularly get mired in evolution discussions on blogs (it's a pet hobby you know), and their inability to grasp the fundemental concept of evolution so concisely put by you baffles me!
Oreo said…
OOOOHHHH, an albino squirrel, I wonder what he would taste like.....
Aginoth said…
Apparently grey squirrels are the best to eat, and Red squirrels taste horrible.
HI! Came on over here from Oreo's blog when you mentioned the albino squirrels. We've got those in our neighborhood too! Nearly invisible against the snow here in Minnesota, but they sure are easy to spot in the summer.
Ditsy Chick said…
Isn't if funny that people's ideas about race come down to such a tiny little mistake?
queenofsass said…
Thank goodness the mystery is solved...we are all just freaks of nature.
magz said…
I like the way ya think David, it's why I keep coming back here, for you rarely fail to set me off on some sort of tangent that stretches my brain.

You're the True Cool amongst bloggers; a man with designer genes.

Best O the Season to you and yours my friend.. want I should ship ya a chicken or 5 for Xmas?
Diane Mandy said…
Anoher interesting post. I actually caught a story on this on NPR. Thanks for shedding more insight!
Lora said…
Interesting I never gave it much thought, but then we would have to find some logical explainations for such differences. Now that we are a more mobile society that has vitamins evailable in pill for I wonder if it makes one wit of difference anymore.
Michelle said…
Fabulous post Dave. I read the full article and 100% agree the person reporting is no scientist.
Fascinating stuff.
utenzi said…
Lora! You're still with us. It's great to see you visiting.

Michelle, thanks for the confirmation. Sometimes I read too much into stuff.

Diane, thanks! Have a great trip...it's only a few days now.

Maggie, I keep trying to find tangents for you to think about.

D. Chick, well--that one nucleic acid just accounts for a third of the color difference. Therre's more to it than just that but more important is that this is only skin color we're talking about. There's a lot more to race than just skin color.
nancy said…
I find this kind of stuff fascinating..... Good post.

Wishing you a Very Merry Christmas!
No_Newz said…
This just makes me happy to be black. You poor white folks are just mutants. hhahaha!
Merry Christmas if I don't "see" you before it comes.
Love, your soul sista,
Lois Lane
Plain Jane said…
All I know is that I am one white "cracker" according to my spousal. *laughs* Here from Michele's.

~ pj ~
That was extremely interesting! (And I normally would not say that) Thanks for putting it into laymen terms for those of us who don't understand Scientific speak, very much.

Wanted to take this chance to wish you and yours a Very Merry Christmas and Happy New Years Utnezi! :-) Headed out of town unti after the New Year. So I'll catch up with you, in 2006!

:-)3T
Pearl said…
Always glad to hear about genetics. Interesting findings.

I'm wary of any news these days because every minutae is tarted up, scientific or not. (There can't even be a vehicle accident, a truck has to slam into a bus on year ago today.)
Miss Ann Thrope said…
backatcha
That was deep, skin deep! :)

Hi, you sent me!

Thanks for visitng my blog! I've been reading Michele for a while before I started blogging, and never have I thought that she could be SCA. I wonder if SCA was Michele's Mr. wonderful?

Have a Merry Christmas, Utenzi!
Michele sent me, HOURS Ago...I got interupted by a wonderful visitor who just left a few minutes ago...Very interesting post...I had never heard this before but it sure makes senseAnd of course, as you said there is a lot more to race than pigmentation...
Grace said…
Interesting article.

In anthroplogy we learned race is a cultural construct. the comment "from dunbaris" posted here describes the theory:
http://www.livejournal.com/users/metahara/25035.html

If we were all blind we would not divide by color. there are other genetic differences we could divide eachother by. Would a blind man know Eminem, Elvis & Tina Marie were "white" if we didn't make a huge issue of it? Would that music exist had slavery not existed?

as for the article- journalists are good at PR these days more than at reporting investigated facts.
Lish said…
You always have interesting and informative things to share with us Utenzi.
poopie said…
Heh. Perhaps if the "journalist" had spent days breeding fruit flies in genetics 101 he or she would have a firmer grasp on the whole thing. My flies never did co-operate.
Oreo said…
HEHEHE HEHEHE Go see what I gave Mom for Christmas......HEHEHE
Nancy said…
Wishing you a Very Merry Christmas.
phoenix said…
Merry Christmas Utenzi!! May your day be all that you could wish for!

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