All blue-eyed humans have common ancestor

January 30, 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.”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.

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.”

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452 Responses to All blue-eyed humans have common ancestor

  1. Sidionie July 31, 2013 at 4:20 pm #

    What happens if you had bright blue eyes and they changed to green then? lol

  2. Anonymous November 17, 2012 at 10:42 am #

    I have blue eyes and my fiance is black. Her grandfather was white like me and also had blue eyes. Possible blue eyes.

  3. Travis November 15, 2012 at 11:41 pm #

    I found the article informative, but reaching. The study group was extremely small, and the genetic evidence does not stand up to other known genetic phenomon.So, this one individual is a common ancester to entire villages in england, to a majority of scandanavians, danish and germanic peoples? I’ve heard the stories of how conquerors such as genghis khan produced offspring carrying his genetic characteristics from china to hungary, in incredible numbers versus the population sample, but there are not entire countries of young genghis’ out there. So, if the khan, while using what is the equivalent of forced intercourse on entire female populations cannot leave a modern result of entire european and western cities bearing asian features, i find it hard to believe that one, unknown individual from the black sea could’ve sired the worlds greatest lineage. Even if the reproductive attraction of blue eyes could explain its proliferation, it explains nothing of the vast areas of tract that blue eyes not only survived in, but become the lone charateristic, breeding out all other eyes…eyes that are dominant to the blues recessiveness. It just doesn’t add up to scrutiny…interesting thought however…

  4. Biologist October 22, 2012 at 10:31 pm #

    The bible says we have a common ancestor two. Um hello Adam??? The first man created by God. Read the bible you two. Do not be biased in life. Read as much as possible!!!

  5. rubix repeater September 27, 2012 at 12:15 pm #

    1 person that they are all descended from, so 1 man/woman is the great great great great, etc etc, grandad/grandmother

  6. Abby September 27, 2012 at 10:50 am #

    Seriously!! What’s wrong with these religious nuts? Nothing about this article has ANYTHING to do with your stupid religion! Do you have a brain???

  7. OMG August 23, 2012 at 8:40 am #

    shut the fuck up.

  8. charito salinas July 7, 2012 at 10:23 pm #

    what do u mean a single common ancestor?

  9. God's Child April 16, 2012 at 8:49 pm #

    I realize I’m a few months late checking in on this one but I only came to this page to help my daughter with her biology homework. Thank you so much for the info the research will be very helpful for her. But the comments, such a great example of a microcosm of humanity. I LOVE IT. The daily intolerance we put each other through is scientific proof that God’s Word is ABSOLUTELY TRUE. If you get a chance read the Bible alongside ANY science books/journals (page for page or however you can manage to balance the weight of both at the same time) the result will change your life. But as I have said before great research; common ancestor might have been one of Noah’s Boy’s :) 10-6000 years ago…I see what you did there.

  10. terri correnti February 29, 2012 at 6:54 am #

    AMEN to that Jill!!! I totally agree with you!!!!!

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