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.”
I was told brown eyes are dominant. My father had brown eyes, my mother blue. How many offsprings would my mother have to give birth to before me and sister who both had blue eyes were outnumberd by brown eyed syblings?
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I have the most beautiful blue eyes ever…almost like a turquoise color – very unique…I have been complemented on it a lot. I am of Friesen (Northern Holland descent) on both side of my parents. Both my parents have blue eyes. My mothers’ mother had brown eyes while her father had blue. My dad’s mother had blue eyes while his father had brown. I have six other siblings and they all have blue eyes. I am very fair and blonde. My mom’s brother who has brown eyes married a dutch brown eyed women. Three of their kids are brown eyed, brown haired, and one boy is very blonde with blue eyes. Just very interesting how genetics plays a role here…I married a German green-eyed man and my oldest son has green eyes and brown hair, while my younger son has blue eyes, very fair skinned and blonde.
*woosh*
ok he did a study! wahoo..! i think it explains a lot. and if brown eyed people (such as myself) are to stupid to realize the difference between gene codes and being adopted then you shouldn’t be reading this should you!
“Also it’s pretty common to call something “neutral” when it has no direct adaptive value even when it *is* strongly selected for by sexual selection (the phenomenon which drove the evolution of the brilliantly flashy but anti-adaptive peacock tail).”
That doesn’t make sense. Peacock tails (or blue eyes) aren’t “anti-adaptive”. If there’s sexual selection inferring some advantage towards reproduction and passing on your genes, i’d say it’s adaptive! I think it’s interesting he’s found the specific mutation and estimated the time line, but i think the rest of what he’s saying about it being a neutral mutation is complete crap.
My mom has brown eyes. My dad has blue. The first kid my sister had blue. I was second i have hazel they sorta change between blue gray and green. The third kid my brother has bown. the next kid my brother had brown. And the last kid my sister had brown. I did notice that my sister first born with blue eyes has blondish brown hair. I had cold black hair(I had the indian gens in me show more) and darker thicker skin. Tan easy. The rest of the kids with the brown eyes all had started out with blondes hair and as they aged it turn to dark brown. I wonder if the hair color and eye color have any thing to do with each other.
i think this study is very interesting and am certin in the future we will dicover what the true meaning of this trait is. im not one for science, never really did it for me. though i will say there are some facts that cant be ignored. im not of a specfific religon but i think we will find in the far off future that this trait has significant bearing in the world of religon.
compasion and empathy gone awrye…
i think as Carl Jung speperated the human race with his studies that this may very well play into his “theories” as he would praise HSP (highly sensitive persons) and i quote “condemn them in the next. At the same time, their differentness is not visible, potentially
increasing the sense of carrying a secret and being an imposter while others think
they are “normal†due to their persona skills, already described.”
youre an idiot
I have dark brown eyes. My dad has honey brown eyes. My mom has almost black eyes (She is Filipino). My dad’s parents both had dark blue eyes. My mom’s parents both have almost black eyes. My husband has blue eyes his parents and grandparents all have blue eyes. Both of my children have blue eyes. Can anyone tell me how this can be? I get confused and I had Biology as a freshman in college.
Some people are born with brown, green, or hazel eyes that fade to blue as they age. To me this suggests that the genetic changes responsible for introducing blue eyes may be varied. Some people with blue eyes may be born without the requisite melanin and others may have experienced a rapid loss of the pigment, even pre-natally. Since blue eyes can be caused either way it seems more than one genetic variant could be at work.
I thought green eyes were the result of yellow fat deposits in blue eyes. So if you and your sibling have green eyes, and your parents have blue eyes, it’s probably because you’re fat.
The gene for blue eyes might co-occur with some other gene (better ability to tolerate the cold, for instance), and might dominate a gene pool simply by piggy-backing on that other gene which *is* selected for.
Also it’s pretty common to call something “neutral” when it has no direct adaptive value even when it *is* strongly selected for by sexual selection (the phenomenon which drove the evolution of the brilliantly flashy but anti-adaptive peacock tail).
In short, blue eyes could have dominated via sexual selection alone.
wonder why the author makes the point that blue eyes are a neutral mutation – going from a single individual to complete dominance over a large geographical area (Nordic countries) in 10,000 years doesn’t sound like the result of genetic drift to me.
I’m with the last comment there. It is very likely for the mutation to repeat itself on multiple non-related incidences and not have to stem from ONE person.
It is still hard to think outside of the linear path and consider that nature is very dynamic and more like a multi-to-multi system than a one-to-many system.
Is there not a possibility that “a genetic mutation affecting the OCA2 gene” could have occured at another time and place, meaning that there would be more than one ancestor?
If that distant ancestor had utilized a condom-like device we wouldn’t have to put up with those blue-eyed devils today in the land of La Raza.
Back to Europe you foreign devils. La Raza is taking back our land.
This is the age of the Chicano/a and you white devils will be shoved out.
Not disagreeing with the other comments made—some I downright agree with. …But when will the rest of the scientific fields take the time to know what the hell they are talking about? There isn’t anything magical about genes, they are nothing more than instructions for coding proteins.
The nearly infinite factors that influence this protein production aside, eye color isn’t some binary, digital trait. It’s not like the pigment is 1) on 2) off…and there are so many cells in the iris that are responsible for color—each one may be governed by a different gene or set of genes for that matter. Remember the Afghani girl on the cover of National Geographic? Like that.
Get over yourselves, act more like scientists and less like tabloid journalists.
Oh for crying out loud, tell me that you did not just introduce Jungian garble into a discussion about allelic frequencies and phenotypic expression. Heck why not throw some Freud in there while you’re at it, genetic reduction in the amount of melanin produced as a conversion disorder!
You’d think after 150 years the days of you people giving the rest of behavioral psychology a bad name would be over. Maybe you can bring Phrenology back as a discipline if you try really hard! :)
/facepalm
who cares, people having a cry cos they don’t have blue eyes, ohhh im not special cos i’m not mentioned on a science blog, why don’t i have blue eyes?? so on so forth. Doesn’t mean you’re adopted.. but then one can’t rule that out. relax a bit. it’s interesting stuff though. especially to a blue eyed person such as myself. be good if they could pin point where the ancestor hailed from.
Wait… so does that mean… if two blue eyed people get married… is that incestuous of them?