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Thread: Blue-eyed people share a single common Ancestor

  1. #1

    Blue-eyed Humans Have A Single, Common Ancestor

    Blue-eyed Humans Have A Single, Common Ancestor

    ScienceDaily (Jan. 31, 2008) — 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.

    “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...

    http://www.sciencedaily.com/releases...0130170343.htm

  2. #2
    Wisey, if genes mutate spontaneously then the complete eradication of certain traits from the human genome isn't really a possibility correct? Unusual phenotypes can arise within populations that are not genetically coded for them. Fewer individuals would become carriers but it would never stop occuring. For example, the oca2 gene responsible for blue eyes is also implicated in albinism as the existence of blue eyes represents the presence of defective melanin producing genes. And since partial ocular albinism can be found within all populations, blue eyes will always be with us. In other words, it will never be a trait that's exclusive to one group or geographical region.
    Last edited by antiquity; 02-02-2008 at 02:37 PM.

  3. #3
    Senior Member rdf's Avatar
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    Blue-eyed people share a single common Ancestor

    One Common Ancestor Behind Blue Eyes

    People with blue eyes have a single, common ancestor, according to new research.

    A team of scientists has tracked down a genetic mutation that leads to blue eyes. The mutation occurred between 6,000 and 10,000 years ago. Before then, there were no blue eyes.

    "Originally, we all had brown eyes," said Hans Eiberg from the Department of Cellular and Molecular Medicine at the University of Copenhagen.
    The mutation affected the so-called OCA2 gene, which is involved in the production of melanin, the pigment that gives color to our hair, eyes and skin.

    "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," Eiberg said.

    The genetic switch is located in the gene adjacent to OCA2 and rather than completely turning off the gene, the switch limits its action, which reduces the production of melanin in the iris. In effect, the turned-down switch diluted brown eyes to blue.

    continued

    --

    I found this interesting because of some articles I've read on some conservative websites. These articles stated that only 3 or 4 or 5 US Presidents had brown eyes, the point being Obama doesn't have a chance of being elected because of his eye color

    I'm from a family of 7, we all have/had deep blue eyes except my dad, who had green eyes. But my family's eyes can change from deep blue to a dominantly green, blue-green color on occasion, usually because of emotion - mainly melancholy, empathy, anger or being hungover. So I wonder if there is a genetic mutation that accounts for that occasional change of our basic eye color from blue to green, and back...

    I've read recently that only 1 out of 6 Americans now have blue eyes. I thought growing up as a kid that blue was the most common eye color, but I was obviously way off.

    If you have blue eyes, you and I share a great great great great, etc., grandma or grandpa. Just call me cousin bob...
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  4. #4
    Well, cousin bob, all my family has blue eyes except my daughter and me, we have green eyes. But both my sons have blue and my parents and grandparents on my fathers side
    TH 12, 43 years post

  5. #5
    Senior Member rdf's Avatar
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    Quote Originally Posted by woman from Europe
    Well, cousin bob, all my family has blue eyes except my daughter and me, we have green eyes. But both my sons have blue and my parents and grandparents on my fathers side
    Hi Cousin
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  6. #6
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    My parents and sister and I are blue eyed too. I always thought brown eyes were exotic and different growing up. lol And since my husband has blue eyes, so do out kids. SO hi cuz!

    (I get the whole blue/brown eye bit. But what about green and hazel? Are they shades of blue and brown?)
    T7-8 since Feb 2005

  7. #7
    Quote Originally Posted by sjean423
    (I get the whole blue/brown eye bit. But what about green and hazel? Are they shades of blue and brown?)
    I think it's the same as red hair, just another genetic difference. Brown is dominant and blue is recessive; I think green is in the middle of the scale.


  8. #8
    Senior Member Ashley's Avatar
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    great grandma are you in here?
    Courage, it would seem, is nothing less than the power to overcome danger, misfortune, fear, injustice, while continuing to affirm inwardly that life with all its sorrows is good; that everything is meaningful even if in a sense beyond our understanding; and that there is always tomorrow.
    -Dorothy Thompson

  9. #9
    hey, i already posted this but nobody responded. i even asked a question.
    http://sci.rutgers.edu/forum/showthread.php?t=95056

  10. #10
    Senior Member rdf's Avatar
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    Sorry antiquity, I thought I'd searched the first couple of pages before posting. Must have missed your thread.
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