4um: All Blue Eyed People Related to Brad Pitt

Title: All Blue Eyed People Related to Brad Pitt
Source: http://www.spiegel.de/
URL Source: http://www.spiegel.de/international/world/0,1518,532346,00.html
Published: Jan 31, 2008
Author: Andrew Curry in Berlin
Post Date: 2008-02-03 21:55:51 by robin
Keywords: None
Views: 1085
Comments: 55

NEW GENETICS DISCOVERY

All Blue Eyed People Related to Brad Pitt

According to a new paper by a Danish researcher, blue eyes come as the result of a single mutation that occurred 10,000 years ago. Which means that all people with blue peepers have a common ancestor.

What do Frank Sinatra, Cameron Diaz, Brad Pitt and Gwyneth Paltrow have in common? According to a new study, they all share the same ancestor.

The paper, published Thursday by Danish geneticist Hans Eiberg in the journal Human Genetics, links all baby blues to a single mutation that occurred 10,000 years ago.

PHOTO GALLERY: BABY'S GOT BLUE EYES

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(5 Photos)

Eiberg says the mutation shuts off the production of the pigment responsible for brown eye color, resulting in a pure blue iris. Because the mutation is so specific, it can only be explained one way: "There must be a common ancestor for people with blue eye color," Eiberg told SPIEGEL ONLINE.

Eiberg started his search for the elusive mutation close to home. Using the Copenhagen Family Bank, a massive genetic database with detailed information on over 6,000 Danes, Eiberg found a family with three generations of blue-eyes. Looking at DNA from their blood, Eiberg homed in on a single, tiny blip in the genetic code. "All of the family had the same mutation," he said.

Originally, Eiberg says, everyone in the world had brown eyes. But the mutation acts as a switch that shuts off the OCA2 gene, which controls the eye's production of melanin. Melanin is the pigment that gives color to eyes and hair.

The mutation limits the OCA2 gene, restricting production of melanin in the eye. The result: The eye's brown color is diluted, giving people with the mutation pure blue eyes. (Shutting melanin production down entirely would result in albinism, affecting hair and skin color as well.)

People without the off-switch, on the other hand, have eye color ranging from deep brown to blue flecked with brown. (Green-eyed people can thank an entirely different part of the genome for their pretty peepers.)

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The mutation is extremely specific: All people with blue eyes have the exact same genetic variation, and anyone with brown or green eyes do not. As a result, Eiberg said, it must have been passed down from a single person. "It's not a guess," Eiberg says. "It has to be."

To make sure the Danish family wasn't a fluke, Eiberg tested hundreds more samples, including people from Turkey with dark hair, light skin and blue eyes and Jordanians with dark hair, dark skin and blue eyes. They all had the same mutation as the Danes. "I have analyzed 800 samples," Eiberg says. "Out of the 800, 799 eyes are the same."

Eiberg has long been fascinated by the genetics of eye color. In 1996, he discovered the OCA2 gene, which helps control eye color. The blue-eye mutation works directly to turn off the OCA2 gene's production of melanin in the eye.

Eye color is a good example of how research is complicating our understanding of heredity. "Eye color is a textbook example of how genes work in a simple way, and now it turns out it's a bit more complicated than that," said Zoltan Bochdanovits, a statistical geneticist at the Vrije University in Amsterdam. "They do present quite convincing evidence it's a single mutation causing this."

Where and when the mutation occurred is more speculative, but based on the number of people with pure blue eyes in the world today, Eiberg argues that the original Ol' Blue Eyes lived between 6,000 and 10,000 years ago. Existing research on prehistoric population movements suggest that the original blue-eyed babe may have lived around the Black Sea, near modern-day Ukraine or Turkey, and that their descendants migrated to Northern Europe during the Stone Age.

Like freckles, hair color or baldness, there's no real physical advantage to being blue-eyed. Says Eiberg: "It simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so."

That doesn't mean eye color isn't important. After all, that long-distant ancestor managed to get quite a few copies of his or her mutation passed along. "I can very much imagine mate choice depends on eye color in humans," said Vrije University's Bochdanovits. "Personally, I tend to believe if you're blond and blue-eyed you have an advantage, at least in some populations."

Anybody else wonder why the 'l' oddball out of the 800 samples? Why no comments about this exception in the article..........with that quantity of samples, is the one loner suggestive of a flawed interpretation of the findings?

I didn't find anything that answered my question, which was brought up because of this:

The mutation is extremely specific: All people with blue eyes have the exact same genetic variation, and anyone with brown or green eyes do not. As a result, Eiberg said, it must have been passed down from a single person. "It's not a guess," Eiberg says. "It has to be."

Mr. Eiberg is the one saying it is the EXACT same genetic variation; that it HAS TO BE; and that of 800 samples, there was l that IS NOT THE SAME.

I want his explanation for the one exception. One in 800 isn't a lot, but when you're talking millions of people, or billions, the exception can be rather significant I think.

His idea of 'every one' and mine is obviously different, as is my definition of 'exact' different than his.

I believe in studies like this, just as in other medical studies, and in polling, the higher the number of samples the greater degree of accuracy. I'm not questioning whether he was accurate in his sampling, I want to know why he makes statements like those noted, and then has an EXCEPTION that isn't explained. :)

Perhaps a bbgG combination might have fooled them into thinking it was a bbgg. Eye color is defined by more than one gene. And clearly there is more to be learned.

I believe there are other studies with more data samples. And from what I learned elsewhere, he isn't quite right about green/hazel/gray eyes having completely different DNA background. They require a bbgg somewhere in their DNA past.

I have hazel blue eyes, only one other of six siblings in my family had eyes that were not brown. So I find this story interesting.

I wonder which eye color determining genes are dominant and which ones are recessive.

Check the wiki and other link I posted. You will enjoy it. Also how eye color can change, I found that intriguing.

i had always heard that brown is the most dominant eye color gene. my father is sicilian with chestnut brown eyes. my mother's are green. my two sisters and i got mom's greens and only my brother got dad's browns. interestingly too, my father is left handed as are both my brother and son--just the males. all the females in the family are right handed.

NEW GENETICS DISCOVERY

All Blue Eyed People Related to Brad Pitt

PHOTO GALLERY: BABY'S GOT BLUE EYES

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