Posted on 01/30/2008 2:10:37 PM PST by decimon
New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of the eye colour of all blue-eyed humans alive on the planet today. What is the genetic mutation
Originally, we all had brown eyes, said Professor Eiberg from the Department of Cellular and Molecular Medicine. But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a switch, which literally turned off the ability to produce brown eyes. The OCA2 gene codes for the so-called P protein, which is involved in the production of melanin, the pigment that gives colour to our hair, eyes and skin. The switch, which is located in the gene adjacent to OCA2 does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the iris effectively diluting brown eyes to blue. The switchs effect on OCA2 is very specific therefore. If the OCA2 gene had been completely destroyed or turned off, human beings would be without melanin in their hair, eyes or skin colour a condition known as albinism. Limited genetic variation
Variation in the colour of the eyes from brown to green can all be explained by the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes. From this we can conclude that all blue-eyed individuals are linked to the same ancestor, says Professor Eiberg. They have all inherited the same switch at exactly the same spot in their DNA. Brown-eyed individuals, by contrast, have considerable individual variation in the area of their DNA that controls melanin production.
Professor Eiberg and his team examined mitochondrial DNA and compared the eye colour of blue-eyed individuals in countries as diverse as Jordan, Denmark and Turkey. His findings are the latest in a decade of genetic research, which began in 1996, when Professor Eiberg first implicated the OCA2 gene as being responsible for eye colour. Nature shuffles our genes
The mutation of brown eyes to blue represents neither a positive nor a negative mutation. It is one of several mutations such as hair colour, baldness, freckles and beauty spots, which neither increases nor reduces a humans chance of survival. As Professor Eiberg says, 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.
Hazel eyes like mine are about what you say, instead of having the code for blue eyes or green being homogenous across the iris you get a hodgepodge of green coded iris cells and brown coded iris cells equally interspersed across the whole iris in varying degrees, sometimes hazel eyes appear close to blue or green while others appear close to brown or amber. In many people with Hazel eyes you get different shades and different colors. My eyes for instance are green and blue with a gray backwash and one brown/black spot. There isnt any real genetic study to explain hazel eyes out there.
The girl who plays Lana Lang on “Smallville” is supposed to be half Chinese and half Dutch, yet her eyes are dark, sort of olive green. If I remember my old biology both of her parents would have to have some light eyed genes. I am not certain tho. Is it possible for a full blooded Chinese to have a green eyed child?
I always like the odds.
Sorry bout the typo. Sometimes I type faster than I think.
Obviously a McCain voter!
Yeah, I always put down brown for my eye color but there are actually several colors depending on the lighting.
bump
Ahem.
When paternity is contested in divorce court, the husband is proven to not be the biological father about 30% of the time.
Just saying.
http://merkel.zoneo.net/Topo/Applet/
That’s kinda my point.
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Recessive gene for you
Unless the hospital swapped babies!
Green is basically a variation of blue eyes. It is very possible for two blue-eyed parents to have a green-eyed child.
The spoise & I both have brown eyes. All our 9 kids have brown eyes. One of our 19 grandkids has blue eyes.
My daughters married blue-eyed guys, but out of their 8 (combined) kids, only one has blue eyes.
Our family’s the opposite: I have blue eyes (but my parents both have green) and hubby has brown.
Our oldest has brown eyes (strange color, though...almost orange), the youngest has my blue.
50-50 chance, and that’s exactly what we got.
Regards,
Green is someother color issue; it’s a color in the fat or something -— so green eyes pop up rather unexpectedly.
That said, I have never been one to chase “ethnic” types — ironic given that I ended up marrying an Army nurse who was 100% born-on-the-reservation Native American -— but the girl from Smallville is the prettiest girl I have ever seen.
the hair and mustache are truly bizarre, forget about the eyes
Green is the color of the Pods. Just sayin'.
If you had brown eyes with two blue-eyed parents, that would mean something was amiss.
Blue-eyed Blonde-hair ping!!!
Interesting that your children were also slow in getting their final eye colors....I was convinced that my oldest (now 12 years old) was going to have green eyes, but at about 3 1/2 they suddenly changed to a strange brown that is almost orange. When I say “suddenly,” I mean within DAYS. It was weird.
Regards,
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