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.”
I have eyes that are described as hazel. Somethimes they are gray, sometimes green, and sometimes blue.
Any info on this changing of color would be appreciated. (I’m too lazy to look it up)
Maybe my eyes were brown when I was younger as well, people told me they were brown. When I was about 35 I was looking at my eyes very closely in a mirror and I said “guess what? my eyes are green with brown centers”. I never thought that they might have changed.
Any info on this changing of color would be appreciated. (I’m too lazy to look it up)
I think that's just a matter of lighting and how deep set your eyes are.
Could it be the clothes I wear giving off some kind of reflection?
I notice the colors change more with the color of my clothes but I didn’t want to say that our front lest someone call me crazy.
I guess. That could go along with the lighting.
I was thinking more of degrees of sunlight, fluorescent lighting versus incandescent lighting...stuff like that.
Well the link at the end is what I have found that best describes, to what degree it can,on what I have learned on eye colors and there coding. While semantically you are arguing the density of melanin, I am trying to say that you are specifically coded for your eye color, be it blue, green or polka dotted. Not saying that the color blue or the color green is created, but that your genes are saying produce x and x amount of melanin, which determines the color of your eyes.(BTW blood vessels behind the eyes are red, which is why albinos have red eyes because they have no melanin, while blue eyes do have some melanin but like the sky you only see blue)
http://www.athro.com/evo/gen/geframe.html
Oxygenated blood is red. De-oxygenated blood is blue. In earth’s atmosphere, you will never see de-oxygenated blood outside the body. As soon as blood is in contact with air, it oxygenates.
Um, clear?
Damn Canadians.
Sure, go ahead and laugh.
I’m afraid to check my mail today.
;-)
Looks interesting. Good luck and stay out of trouble over there.
OK, my siblings and I are all blue eyed. WHO is our common ancestor? I’m claiming Adam...
Uh, oh, my oldest grandson looks like Putin...
My father had lovely cornflower blue eyes. We’re all blue eyed but not as bright and beautiful as his were.
I’ve got my eye on you...
My dad had blue eyes, mom’s were more hazel. We’re all blue eyed blonds.
Yes they did! Raping and pillaging their way around France, Ireland, America...
I dunno. Do you bark and eat your food out of a dish on the kitchen floor???
Germany, England, Scotland, Iberia, Northern Africa, Rome, Sicily, Naples, Russia, Ukraine, Byzantium...
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