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Blue-eyed Humans Have A Single, Common Ancestor

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  • 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.

    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.”

    Adapted from materials provided by University of Copenhagen.

    University of Copenhagen (2008, January 31). Blue-eyed Humans Have A Single, Common Ancestor. ScienceDaily. Retrieved January 31, 2008, from http://www.sciencedaily.com* /releases/2008/01/080130170343.htm
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  • #2
    Re: Blue-eyed Humans Have A Single, Common Ancestor

    One Common Ancestor Behind Blue Eyes

    31 January 2008

    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, so 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.

    If the OCA2 gene had been completely shut down, our hair, eyes and skin would be melanin-less, a condition known as albinism.

    Depending on the amount of melanin in the iris, a person can end up with eye color ranging from brown to green. Brown-eyed individuals have considerable individual variation in the area of their DNA that controls melanin production. But they found that 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," Eiberg said. "They have all inherited the same switch at exactly the same spot in their DNA."

    http://www.livescience.com/health/080131-blue-eyes.html
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    • #3
      Re: Blue-eyed Humans Have A Single, Common Ancestor

      How one ancestor helped turn our brown eyes blue

      By Roger Highfield, Science Editor
      30/01/2008

      Frank Sinatra, Stephen Hawking, Marie Curie and Stephen Fry all owe their blue eyes to a genetic mutation that likely occurred between 6,000 and 10,000 years ago, researchers say.

      Scientists believe they have tracked down the cause of the eye colour of all blue-eyed humans on the planet today.

      “Originally, we all had brown eyes”, said Prof Hans Eiberg from the University of Copenhagen, who led the team.

      Blue eye colour most likely originated from the near east area or northwest part of the Black Sea region, where the great agriculture migration to the northern part of Europe took place in the Neolithic periods about six–10,000 years ago.

      “That is my best guess,” he said. “It could be the northern part of Afghanistan.”

      The mutation affected a gene called OCA2 and “literally 'turned off' the ability to produce brown eyes”, he says.

      OCA2 is involved in the production of melanin, the pigment that gives colour to hair, eyes and skin.

      The mutation in the adjacent gene does not switch off the OCA gene entirely but limits its action, reducing the production of melanin in the iris of the eye – “diluting” brown eyes to blue.

      If the OCA2 gene had been completely turned off, those who inherited this mutation would be without melanin in their hair, eyes or skin colour - albino.

      For the study, Prof Eiberg’s team examined DNA in blue-eyed individuals in countries as diverse as Jordan, India, Denmark and Turkey.

      His findings are the latest in a decade of genetic research, which began in 1996, when Prof Eiberg first implicated the OCA2 gene as being one of those responsible for eye colour.

      “They have all inherited the same switch at exactly the same spot in their DNA. From this we can conclude that all blue-eyed individuals are linked to the same ancestor,” said Prof Eiberg, who reports the work in the journal Human Genetics.

      http://www.telegraph.co.uk/earth/mai...scieyes130.xml
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      • #4
        Re: Blue-eyed Humans Have A Single, Common Ancestor

        There is common ancestor for all blue, green, brown eyes, haired, tall, short, fat, thin, white, brown, black, yellow skinned ppl. The father is Adam (as) & mother is Hawa.
        Financial freedom is a matter of choice. We came into this world sustenance-guaranteed from our creator. However, it is our choice to be enslaved by money.

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        • #5
          Re: Blue-eyed Humans Have A Single, Common Ancestor

          How one ancestor helped turn our brown eyes blue

          By Steve Connor, Science Editor
          Thursday, 31 January 2008

          Everyone with blue eyes alive today – from Angelina Jolie to Wayne Rooney – can trace their ancestry back to one person who probably lived about 10,000 years ago in the Black Sea region, a study has found.

          Scientists studying the genetics of eye colour have discovered that more than 99.5 per cent of blue-eyed people who volunteered to have their DNA analysed have the same tiny mutation in the gene that determines the colour of the iris.

          This indicates that the mutation originated in just one person who became the ancestor of all subsequent people in the world with blue eyes, according to a study by Professor Hans Eiberg and colleagues at the University of Copenhagen.

          The scientists are not sure when the mutation occurred but other evidence suggested it probably arose about 10,000 years ago when there was a rapid expansion of the human population in Europe as a result of the spread of agriculture from the Middle East.

          "The mutations responsible for blue eye colour most likely originate from the north-west part of the Black Sea region, where the great agricultural migration of the northern part of Europe took place in the Neolithic periods about 6,000 to 10,000 years ago," the researchers report in the journal Human Genetics.

          Professor Eiberg said that brown is the "default" colour for human eyes which results from a build-up of the dark skin pigment, melanin. However, in northern Europe a mutation arose in a gene known as OCA2 that disrupted melanin production in the iris and caused the eye colour to become blue.

          "Originally, we all had brown eyes," said Professor Eiberg. "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."

          Variations in the colour of people's eyes can 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, he said.

          "From this we can conclude that all blue-eyed individuals are linked to the same ancestor. They have all inherited the same switch at exactly the same spot in their DNA," said Professor Eiberg.

          Men and women with blue eyes have almost exactly the same genetic sequence in the part of the DNA responsible for eye colour. However, brown-eyed people, by contrast, have a considerable amount of individual variation in that area of DNA.

          Professor Eiberg said he has analysed the DNA of about 800 people with blue eyes, ranging from fair-skinned, blond-haired Scandinavians to dark-skinned, blue-eyed people living in Turkey and Jordan.

          "All of them, apart from possibly one exception, had exactly the same DNA sequence in the region of the OCA2 gene. This to me indicates very strongly that there must have been a single, common ancestor of all these people," he said.

          It is not known why blue eyes spread among the population of northern Europe and southern Russia. Explanations include the suggestions that the blue eye colour either offered some advantage in the long hours of daylight in the summer, or short hours of daylight in winter, or that the trait was deemed attractive and therefore advantageous in terms of sexual selection.

          http://www.independent.co.uk/news/sc...ue-776170.html
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          • #6
            Re: Blue-eyed Humans Have A Single, Common Ancestor

            Originally posted by Le Croyant View Post
            There is common ancestor for all blue, green, brown eyes, haired, tall, short, fat, thin, white, brown, black, yellow skinned ppl. The father is Adam (as) & mother is Hawa.
            How do you explain the scientific findings then?
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            • #7
              Re: Blue-eyed Humans Have A Single, Common Ancestor

              Originally posted by Le Croyant View Post
              There is common ancestor for all blue, green, brown eyes, haired, tall, short, fat, thin, white, brown, black, yellow skinned ppl. The father is Adam (as) & mother is Hawa.
              yes but doesnt it mean that later on after that, one person's eyes turned blue then the rest of them came from that one's line... but ultimately all from adam alayhi salam, so that includes all the people with dif eye colours

              but this scientific explanation for the blue, does a similar thing apply to green? or no?
              .: Rufaida :.
              .:Fa Firroo Ila-llaah:.
              http://s61.photobucket.com/albums/h6...th_Silence.jpg
              “People praise you for what they suppose is in you,
              but you must blame your soul for what you know is in you.”
              ~ Ibn Atallah

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              • #8
                Re: Blue-eyed Humans Have A Single, Common Ancestor

                Originally posted by .: Anna :. View Post
                but this scientific explanation for the blue, does a similar thing apply to green? or no?
                No the article says green is to do with the melanin so is the same as brown and all varying colours in that spectrum. Just the blue is a seperate ancestor.

                I am assuming grey is with blue.
                Freedom has a thousand charms to show,
                That slaves, howe'er contented, never know.
                -William Cowper

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                • #9
                  Re: Blue-eyed Humans Have A Single, Common Ancestor

                  Originally posted by Arrakis View Post
                  No the article says green is to do with the melanin so is the same as brown and all varying colours in that spectrum. Just the blue is a seperate ancestor.

                  I am assuming grey is with blue.
                  oh okay. i did read it all but i am not that scientific minded so i dnt always get it
                  .: Rufaida :.
                  .:Fa Firroo Ila-llaah:.
                  http://s61.photobucket.com/albums/h6...th_Silence.jpg
                  “People praise you for what they suppose is in you,
                  but you must blame your soul for what you know is in you.”
                  ~ Ibn Atallah

                  Ramadan Activities for Children
                  <button id="tw_schedule_btn" class="tw-schedule-btn" style="padding: 4px 6px;position: absolute;left: 141px;top: 840px;background-color: #F7F7F7; background: linear-gradient(#FFF, #F0F0F0); border: 1px solid #CCC; color: #5F5F5F; cursor: pointer; font-weight: bold; text-shadow: 0 1px #FFF; white-space: nowrap;border-radius: 3px;font-size: 11px; display: none; z-index: 8675309">Schedule</button>

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                  • #10
                    Re: Blue-eyed Humans Have A Single, Common Ancestor

                    Originally posted by Arrakis View Post
                    How do you explain the scientific findings then?
                    how do the scientific findings in this study contradict the idea that all humans share a single ancestor?

                    answer: they dont. he doesn't have to explain anything...
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                    • #11
                      Re: Blue-eyed Humans Have A Single, Common Ancestor

                      Originally posted by .: Anna :. View Post
                      yes but doesnt it mean that later on after that, one person's eyes turned blue then the rest of them came from that one's line... but ultimately all from adam alayhi salam, so that includes all the people with dif eye colours

                      but this scientific explanation for the blue, does a similar thing apply to green? or no?
                      i agree with u... what i meant was we should not be totally surprised by such findings.
                      Financial freedom is a matter of choice. We came into this world sustenance-guaranteed from our creator. However, it is our choice to be enslaved by money.

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