Blue eyed people have a single, common ancestor
Nature constantly ”shuffles” our genes around in our genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so. Some of these changes represent neither a positive nor a negative mutation or a competitive advantage. One such ’shuffle’ is eye color.
Originally we all had brown eyes. Then about 6-10,000 years ago a genetic mutation in the OCA 2 gene arose causing a ’switch’ which literally switched off our ability to produce brown eyes.
The OCA 2 gene codes for the so-called P gene which is involved in the production of melanin, the pigment that gives color 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. If the OCA2 gene had been completely destroyed or turned off, human beings would be without melanin in their hair, eyes or skin color – a condition known as albinism.
Variation in the color 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 it can be concluded that all blue-eyed individuals are linked to the same ancestor. Blue eyed people 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.
Elaine Warburton www.geneticsandhealth.com
This is so interesting. I remember studying about genetics and eye colour, oh so many years ago, but I haven’t thought about it.
My youngest of three kids has blue eyes and he’s the only one in the immediate family who does. He has a little pie slice of brown in one eye. It’s quite noticeable too.
My husband and two other children have brown eyes and mine are yellow with a hint of green.
It’s funny to look at the breakdown because my parents, my father’s eyes were grey/blue and my mother’s very brown. But both my inlaws had blue eyes (I think).
I love looking at eye colours in families and hair colour. The combinations can be really interesting.
You know, when I was in school, we were just taught that blue eyes were recessive and brown eyes were dominant. A dominant always overshadowed the recessive. That was it.
Isn’t it funny to think how simplistic that sounds when looking at the true nature of genetics?
Great, interesting post!
A mother of mixed race married a white man and has a pale white daughter who married a white man. What are the chances of their child being black? The blood test of the unborn child shows a high percentage of non caucasion blood. What does that mean?Would they have done a comprehensive genetic test at this stage? Can they tell that the unborn child has a dark skin? The grandmother does not appear to be dark skinned at all. This is my nephew and I am curious but don’t want to ask them too many questions.
The one question no one seems to ask is… Who is she… was this Moses wife they are speaking of? It was believed by some that she may have been dark skinned and some believed Mary M to be darked skinned. Lots of questions but where are the answers, you would think they would come forth with such information.
What does Moses wife has to do with any of this???Nothing, if you ask me… Interesting text, I didn’t know there were people with blue eyes and hints of brown in it, sounds cool!
Interesting comment, But I bet you will find you could be mistaken.
There were many ancient belief forms on Moses wife, Jesus, and Mary M… in this very area.
I can admidt when I am wrong. However… I have done years of research in this very area on tons of levels.
I also took heavy genetics courses in college and research. I could go on to conclude the reasoning. But I will leave it up to the experts to string you along for some time until they explain who it is they know this person to be as they claim they do, but have not yet released.
Then If… I am wrong I am a big enough person to admidt it. No worries just means I missed a essencial key in research. None the less.. All is good, I simply enjoy my work!
The reason it was caused by a woman is the gene is only passed down by mothers. See below additional information you may not have been privey to.
Eiberg and colleagues examined DNA from the mitochondria, a cellular compartment passed down only through “mothers”. They also compared eye colour of blue-eyed people from in countries as diverse as Jordan, Denmark and Turkey. The findings are the latest in a decade of genetic research that Eiberg said began in 1996, when he first implicated the OCA2 gene in eye colour.
Final tid bits to assist evolving this story with facts.
Professor Eiberg was the first to implicate the OCA2 gene as being responsible for eye color, among other things. Since that implication, back in 1996, Eiberg has worked hard to reach conclusions such as these.
The mutation in the OCA2 gene effects the production of melanin, the biological pigment that gives color to our hairs, eyes and skin. According to Eiberg the mutation dials down the levels of melanin in our eyes, thus creating the popular blue.
By way of contrast, a human being without any melanin in their body would be an albino.
Eiberg has also managed to place a “best guess” on the location of where this mutation took place. He believes that it originated from the near east or northwest areas of the Black Sea region. This location is where the great agriculture migration to the northern part of Europe took place, during the Neolithic period 6,000 to 10,000 years ago. However, he stresses his unsurely; “That is my best guess,” he said. “It could be the northern part of Afghanistan.”
That genetic switch somehow spread throughout Europe and now other parts of the world.
“The question really is, ‘Why did we go from having nobody on Earth with blue eyes 10,000 years ago to having 20 or 40 percent of Europeans having blue eyes now?” Hawks said. “This gene does something good for people. It makes them have more kids.”
The OCA2 gene is not only passed down by mothers and the gene is not only responsible for eye color. Genetic mutation/variation also causes two diseases Prader-Willi (from the paternal chromosome) and Angelman (from the maternal chromosome) syndromes. Symptoms are hyperphagia and food preoccupations, as well as small stature and learning difficulties.
It also does not cause blue eyes alone. People with the same OCA2 haplotype can have blue, gray, green, hazel or brown eyes. In fact, the variations in the OCA2 exonic sequence are not population/race/color specific. Only in the first intron (not used to make the protein) has an association to blue eye color as well as European descent in general (all eye colors included). Blue eyed people have about a dozen different haplotypes (different nucleotide combinations) in this area, all of which were also in people with every other eye color. This non-coding region which the article above is really about seems to be one of many factors in decreasing or increasing melanin indirectly.
Seeing that eye color is more complicated then a single mutation, I doubt that it came from one person.
why does having blue eyes make people have more kids?
Just looking up this story – I missed it last year. Came across another story that theorized blue eyed women were preferred as mates by blue eyed men because the offspring with blue eyes would be proof of paternity. A weak argument at best. Heard nothing of the Moses mother theory brought up in comments.
Was curious how this fits into the Amazonian Warrior Women legends – there was a Nova I saw on that and they did trace them to Mongolia…