Wednesday, June 3, 2009

Don't it make my brown eyes blue


All Blue-eyed humans have common ancestors


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 color 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 color 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 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 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 color. 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 color, 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.”





8 comments:

Vicky said...

Wow, I had know idea!! What an interesting piece of research. I was totally humming Crystal Gayle's song while I read this :)

Thom said...

You are a woman of such knowledge. I also have been humming don't it make your brown eyes blue as well...Thanks for the info

Nessa said...

And here I thought all brown eyed people were full of doody and blue eyed people were just cleaned out. Not very scientific, huh?

:-)

A Free Spirit Butterfly said...

You are my personal little encyclopedia (smile)

I've missed you.

Love and hugs
China

Cindy said...

That is so interesting and amazing! Now, I wonder who that common ancestor is!

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jinksy said...

What an intriguing post. Not quite sure where it leaves my grey eyes, but at least they are smiling! Thanks for visitng my corner of Blogland...

A Lady's Life said...

Thanks guys for visiting:)

Welcome back Free Spirit!

I guess the article explains that we are, like the world, constantly changing.
In the future man may end up with pink eyes for all we know lol

We are like the pink flamingoes who turn pink because of what they eat.
As our planet changes, so do we and maybe this is a good thing because we will not have the same issues on race like we do now.

Happy Hunting every one!!!!:)