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 switch’s 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 human’s 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.”
Thats not quite true, as far as I have been taught. Humans are in fact coded with the ability to produce green, which isnt a variation of blue and brown. Now Hazel can be a variation of blue and brown or brown and green. Its all on how your pigmentation, density and melanin are coded.
Now any color that isnt blue,green or brown are either a mixture of those or a true genetic mutation.
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Yeah. I remember him. He used to live in a mud hut over in shoot holler. We used to call him Old Blue’s Eyes. He was Old Man Brown Eye’s boy. Sharp as a bag of pillows but the girls liked him.
There are also blue people in Kentucky, Ireland and Scotland
Heh.
No. My father is. ;-)
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Thanks decimon for the topic and ping, and thanks CholeraJoe and Fractal Trader for the additional pings. I'm counting out time, Got the whole thing down by numbers. All those numbers... |
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How about the dogs and cats with blue peepers? Have they a common ancestor or does this thing happen now and then? Except to humans where it only happened once.
My money’s on the milkman:) Seriously-don’t know bout brown eyes,but i have heard(don’t know for sure)a blue eyed couple cannot produce a brown eyed child.
I don't know about the animals but I'd like to know why they conclude a single mutation among the humans.
If two blue eyed parents had a brown eyed child then the milkman may have been involved, or some other brown-eyed male.
No...God has blue eyes. ;)
I’d love to be behind Crystal Gayle. Being in front of her would be even better.
“Although not common,two blue eyed parents can produce brown eyed children.”Thanks for the link.Interesting article.
Correction, you both have mutated brown eyes, like me ;-).
This will explain some of that:
Lots of people carry the blue gene, even if it doesn’t show. This covers a lot of territory.
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