Where'd Ya Get Those Baby Blues?

Geneticists Trace Blue-Eye Gene To Mutation From One Individual

(CBS)  From Paul Newman to Frank Sinatra to Cameron Diaz. From residents of snowy Moscow to Palestinians in Jerusalem.

Danish geneticists say everyone with blue eyes is not just related, but descended from one person, CBS News correspondent Sheila MacVicar reports.

In the basement of the University of Copenhagen, frozen in vats of liquid nitrogen are thousands of DNA samples.

"This is like our secret, our gold mine," said Prof. Jesper Troelsen, a geneticist. "We dig down and find the samples we are going to use and ask specific questions about genetics."

And this time the question was, "what makes blue eyes blue?"

"All people with blue eye color have a special fingerprint," said gene mapper Hans Eiberg.

Brown, they say, is the default color for human eyes ... produced by melanin.

Blue eyes are caused by a genetic switch, programmed to suppress the melanin. It's a genetic mutation.

And in the DNA of hundreds of blue-eyed people tested by the Danish team, they found exactly the same mutation every time.

"And what would the chances of that coming from more than one person? It has to be from one person?" MacVicar asked.

"Yes, we are very sure," Eiberg said.

The first blue eyed person was probably born near the Black Sea just 10,000 years ago when the entire population of the world was less than 50,000.

Those mutant genes spread on a wave of human migration.

Today, nearly 95 percent of Scandinavians have blue eyes.

What scientists don't know is if having blue eyes was some kind of evolutionary advantage … if blue-eyed people could see better in the low winter light of Northern Europe for example. Or, was it just about downright attractiveness?

Genetics really can turn your brown eyes blue, and now, there is a whole new answer to that question: "Where did ya get those eyes?"

[Lettymoreno22]

my parents and grand parents on both sides have dark brown eyes, I don't understand how I got the bluest eyes ever, I am not adopted, the Dr says it just happens.

[lheureblue]

"How can you explain one blue eye and one brown eye, like my 2 cousins? How could one gene be responsible? Did they get half?"

"Scientists have long known that not all the cells in your body necessarily have the same DNA. Many people have some cells with completely different DNA than other regions in their bodies. Or it could be that in one eye, the gene is switched on and in the other it is switched off. Or it could be that their phenotype is different that their genotype. Only a geneticist could tell for sure."

The article says there''s a single mutation...and it''s an off switch, to supress the melanin. But, you''re right, perhaps there is a right or left side override mechanism in my 2 cousins. Ohmigosh, maybe this is an indicator of some inner eye irregularity?? What else is this mechanism overriding??

Why don''t they offer my cousins a free trip to Copenhagen to study them? I think there are other people out there like them. Bring them all to Copenhagen! (Sorry, something inside me has just overridden its mechanism...)

[rushlimpdrug]

So ALL the blue-eyed people came from ONE person that was mutated?

What a KROCK of chit!

ONE person and only one could have had this mutation?

These "scientist" are the most profoundly stupid idiots on the planet.

They''ve been eating to many twinkies.

[tiberius1701]

No one has mentioned that it is easier for brown-eyed people to become snow-blind. In northern europe during a glaciation period brown eyes would be a disadvantage.

[fain6]

DON''T FORGET THAT WHEN 2 RESESSIVE GENE ALLELE "CROSS" A PERSON CAN HAVE NO DOMINENT GENE FOR BROWN EYES EVEN THOUGH THE PARENTS MAY HAVE BROWN OR "HAZEL" EYES. I HAVE BLUE EYES, MY PARENTS HAVE BROWN EYES. AH HA! YOU SAY...WELL, 3 OF MY GRAND PARENTS HAD BLUE EYES GIVING A RECESSIVE GENE TO EACH OF MY PARENTS.THOSE RESESSIVE GENES REPLACED (BY CROSSING OVER) THE DOMINENT BROWN GENE. WHICH IS WHY MY EYES ARE BLUE.

10,000 years to reach six billion from only 50,000 people?

Don''''t think so.

==
That''s about 17 doublings in 10,000 years, or a doubling every 588 years. Sounds quite plausible to me.

[rushlimpdrug]

Posted by markcapik at 11:07 AM

You made my head hurt!

Anyway, I wake up with green eyes but when I go to sleep my eyes are red.

Why is that doctor?

My friend tells me it depends on what girl he takes home as to what colored eyes he wakes up with.

[rf35]

Oh, look. Another Danish study. Is that all those people do?

[connapa]

To follow up on emma''s comment, the first person may have been ostracized from their group, thereby moving outward into the world. repeat this a few hundred times, and eventually you are in scandinavia. Put that together with blue eyed people only reproducing and associating with other blue eyed people, and you get what we currently have.

[oleander8]

"10,000 years to reach six billion from only 50,000 people? Don''t think so."

Try this: your Dad gives you a penny on the first day of the month, the next day he gives you 2 pennies, the next day he gives you 4 pennies, the next day 8 pennies --- and so on, for 30 days. At the end of the month you would have $5,368,709.12 - all in just 30 days.

[markcapik]

Wow, there are really some ill informed (read stupid) people commenting on this

First off, 10000 to six billion is easy. have you actually ever seen a FULL family tree? Each generation can easily double in size. Also, their is usually more than one generation alive at any time.

Second, have you ever seen a punnet square. You could have blue, you significant other could have green, and you could still get the very rare purple eyed child. Genetics is somewhat random. You could have a dominant and recessive gene and come up with some cool endings.

http://en.wikipedia.org/wiki/Punnett_square

Thats for all how don''t know what i am talking about.

And evolution is ran by 3 tenets:

More beings are born than could survive. (humans excluded)
These beings have variations.
Their environments are different.

So evolution says that those beings who''s variations help them survive best in their environment will have kids who most likely will keep their parents variations.

So blue don''t seem to help with survival, but maybe the progenitor had something else that did.

Okay that is enough high school science for you all. I don''t want to make your heads hurt

[emma915]

I wonder if that first blue-eyed person was considered good luck or bad luck to his or her tribe. . . . . (Must have been good luck, ''cuz we''re still here to mutate further. ..)

[dogsoul]

"What world has had less than 50,000 people in it? Are you counting Africa, and China, the original continents we now call north and south America, or simply Caucasia? 10,000 years to reach six billion from only 50,000 people? Don''''t think so."

Huh? Ever hear of exponential growth?

[brianbwb-2009]

The first blue eyed person was probably born near the Black Sea just 10,000 years ago when the entire population of the world was less than 50,000.

What world has had less than 50,000 people in it? Are you counting Africa, and China, the original continents we now call north and south America, or simply Caucasia?

10,000 years to reach six billion from only 50,000 people?

Don''t think so.

[sfray5]

10,000 years ago, the world had very little people. It was due to hunter/gatherers settling down to farm and building civilization that allowed for the rapid increase in population. The surplus in food, clothing, and tools due to specialization in the workforce meant increased population. Actually, the world's population wasn't anywhere near 6 billion 200 years ago. In 1800, there were only 1 billion people on earth. The fact is that we are increasing exponentially and the world is getting overcrowded because of modern advances in technology.

[dogsoul]

What about green eyes? My wife & I have a mix of green & brown - and our daughter was born with blue eyes.... she''s also got wings and can fly.

[extremophil]

So this means that we''re all descended from Paul Neuman??

[excoachken]

Sooooo, Mr. Smartypants, how come I don''t sing like Sinatra?

[biomedart]

Ah ***...both my parents have blue eyes haha!

Great story though! Thanks for having something interesting and uplifting to bring to the table! I feel like the news has been so depressing lately.

[otdky07]

I have blue eyes and so does my wife. The great thing about this is that if we have a child who has brown eyes, I''ll know it''s not mine right away!

[mennowoman]

"How can you explain one blue eye and one brown eye, like my 2 cousins? How could one gene be responsible? Did they get half?"

Scientists have long known that not all the cells in your body necessarily have the same DNA. Many people have some cells with completely different DNA than other regions in their bodies. Or it could be that in one eye, the gene is switched on and in the other it is switched off. Or it could be that their phenotype is different that their genotype. Only a geneticist could tell for sure.