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.”
All of us still have one brown eye. Sometimes I can make mine blink.
Bright light?
I’d like to see the actor on the right (name escapes me, though I know he’s the “new” James Bond) take over the Martin Cruz Smith character of ‘Arkday Renko’ played by William Hurt in ‘Gorky Park.’
They need to make ‘Wolves Eat Dogs’ (the new Renko story) into a movie. He would be awesome in the lead. :)
(I know this has nothing to do with anything, LOL!)
Not her actual eyes??! ;-)
Both my parents have/had blue eyes. My mother's stunningly so. Mine are green, the same green as the green flecks in my maternal grandfather's brown eyes.
How did Liz get violet eyes?
“Bright light?”
Nah, fear.
I went to college with a guy like that - one blue eye, one brown.
Yeah, but how do you feel?
Nice pic of the Husky. I used to work with a lady who had one brown eye and one blue eye. I once asked her how she filled out her driver’s license information about her eye color. She said she always wrote “Blue” since that was her dominate eye...made sense i guess.
My eyes are similar. They still look mostly brown, but have pools of green throughout the reddish brown. However, as a child, my eyes used to be a very dark brown.
This is also true of my dad and two of my brothers. They started with dark brown eyes when younger. My dad and one brother are almost completely green now and my other brother’s hazel. I’m the youngest, so I figure it will be another 15-20 years until my eyes are green. Weird.
Am I evolving?
Cordio
That’s the funniest thing I have ever read.
Damn Canadians.
I tell her that our future children are going to have brown eyes. That's not quite right, is it?
Nope....odds are 50-50 for blue eyes vs some brown/green combo
Does that mean our daughters don't share our ancestry?
Not at all...
Your husband is a heterozygote with both a blue and brown eye gene....brown eye color is the dominant gene expression. At some point in his family tree he had a blue/green eyed relative.
People with green eyes have a blue eye gene too...the eye color gene is subject to variable penetrance which can lead to different ‘shades’ of color from dark brown to green etc.
Your two daughters eye color has nothing to do with their ‘ancestry’...
each of your children
We all have a single, common ancestor. We have Adam and Eve and we all also have Noah. I wonder about them calling my blue eyes a mutation. Were they not just a distinct variation and recessive in the original brown eyed pair? Why do they think that they were a mutation? What do they actually know and are going on to believe that blue eyes are a mutation? They do not seem to think that all the different intensities and hues of brown and green are mutations or at least they do not label them as such. Is not the melanin turned on and off to all different degrees in these folks?
What was Adam and Eve's daughter's name?
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