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.”
My husband has dark Teal colored eyes, and I have extremely light Dresden Blue eyes, and we had three children, all of them have Brown eyes. One of them has Brown-Green eyes, but they all are considered to have Brown eyes. I was blonde till I was in my twenties, and my husband had dark brown hair, all of our children have dark brown hair.
It’s perfectly possible for something like that to happen with hair color.
I know someone, who’s hair started with brown, then became blond, and later became ginger. This person also has the same thing going on with her eye color: first blue, then brown, and then green.
my own hair has it’s fun too. I was first a blond, then became brown, later black, and now it’s blond again.
It’s a strange thing, mainly caused by hormons. Genetics work though hormons; By a defect, or the work of an other gen, It’s possible for people the change hair and eye color.
For most of us, this stops after puberty, when the hormones find a correct balance. However, if it’s caused by a different gen, it’s possible that this goes on for the rest of your life.
My husband has dark Teal colored eyes, and I have extremely light Dresden Blue eyes, and we had three children, all of them have Brown eyes. One of them has Brown-Green eyes, but they all are considered to have Brown eyes. I was blonde till I was in my twenties, and my husband had dark brown hair, all of our children have dark brown hair.
no, she cheated
Eh?
Brown eyed parents can of course have blue eyed children but thats because they have the gene for blue eyes in their genotype. Their grandparents or parents or any relative of the sort HAD had to have blue eyes in order for their children to have blue eyes which is a result of a recessive gene. If both parents have the genotype Bb Bb, brown would show up in their eyes (lowercased b inherited from parents) but through a 25% chance that their offspring would have bb then the child would have blue eyes. The blue eyed gene had have to come from somewhere for the newborn to have blue eyes, therefore proving that all blue eyed humans share a common ancestor. So this theory is true. (This is just a response proving to someone that this theory is indeed true)
Brown eyed parents can (and often do) have blue eyed children. Blue eyed parents are not likely (if it’s even possible?) to have brown eyed children.
Yah, having a certain color of hair or skin or eyes can be a sexual advantage. However, blue eyes are not that big of an advantage when it comes to attract a mate. Not all people are attracted to blue eyes. Not all people are attracted to fair skin. Every person is attracted to different things, and genetics can play a role in what someone is attracted to but experiences and situations in that persons life plays a role too. A blue eyed girl may not have an advantage over a green eyed or brown eyed girl if that particular male is more attracted to green eyes or brown eyes, or darker colors in general. Most men are attracted to tan skin these days, blue eyed people are rarely tan. Therefore tan people have an advantage over fair people. On the other hand some men like fair women. In general the sexual attraction thing between coloring evens out. We are diverse in our looks and diverse in what we are attracted to. So, yes I would say that blue eyes is definitley a neutral mutation. It may be useful in certain circumstances but not all, therefore it is neutral. Developing a bigger sized brain, well see that is not neutral because its what put us at the top of the food chain. However, blue eyed people arent at the top of the sex chain.
blue is recessive and brown is dominant…..there would be a zero percent chance of having a blue eyd child.
That is true in most cases. But there are several cases that have a domiant blue, and a ressive brown.
So it is possible.
blue is recessive and brown is dominant…..there would be a zero percent chance of having a blue eyd child.
No, that means nothing. If a brown eyed person (with all brown eyes in ancestry) and a blue eyed person (with all blue eyed ancestors) have a child, that child has a 1 in 4 chance of having blue eyes.