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.”
And a busy boy was he.
Wait...so if two blue eyed people get it on...it’s incest?
(singing)
...and don’t it make my brown eyes
don’t it make my brown eyes, blue.
I’ll play along. I have blue eyes. My parents have brown eyes. Is my father my father? /lol
Ping bleu
Both your parents carried a recessive gene for blue eyes. They had a four in one chance of any child having blue eyes.
I knew there was a song about this! This scientest is way behind Crystal Gayle!
Damn I am a mutant!
Uhhhh....
Here’s your sign.
Interesting. My husband and I have blue eyes.
You are correct. Actually I got my paternal grandmother’s eyes.
Now if both your parents had blue eyes and you had brown eyes, the answer would be no.
Parthenogenesis?
DNA tests?
/lol
So I have blue eyes and my wife has brown eyes. Her mother had blue eyes, her father brown.
I tell her that our future children are going to have brown eyes. That's not quite right, is it?
uh oh... ; )
LOL
There were eight people on the ark, Noah, his wife, the three sons and their wives.
I guess one of them was blue-eyed. At least the time line (6 to 10,000 years ago) is correct.
fishtank, Ph.D.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.