Tag: DNA

Scientists used to think that blue-eyes were introduced to Europe by farmers who arrived late to the continent. New research shows that the genes responsible for blue eyes may have already been there amongst dark-skinned hunter-gatherers.

An analysis of the DNA of a 7,000 year old skeleton found in a cave in Spain showed that the male carried the African version of genes responsible for the light skin pigmentation of Europeans—meaning he had dark skin—along with the genetic variation that causes blue-eyes.

Makes me wonder where along the line the genetic variation occurred. I doubt this is the very first blue-eyed person.

I’d always thought it likely that blue-eyes and light skin were a genetic response to the need for less pigmentation due to the weaker sunlight of northern Europe. But maybe not. I’d hardly call Spain a northern climate.

I guess we’ll have to see what future scientific discoveries can tell us.

The article “Blue-eyed humans have a single, common ancestor” in the Innovations Report states that:

“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.”

Unlike green eyes—which, according to the article, are only a variation of brown—blue eyes are not merely a variation of the amount of melanin in the iris. The genetic mutation actually “resulted in the creation of a ‘switch’, which literally ‘turned off’ the ability to produce brown eyes.” The switch doesn’t completely turn off the ability to produce melanin in the iris, but reduces the production of melanin in the iris to the point that brown eye color is completely diluted to blue. Any variation in the amount of melanin in the iris in a blue-eyed person would then only change the shade of blue. Cool.

So, I wonder how that got passed on. The trait is a recessive, meaning you need to get it from both parents. Does that mean that our blue-eyed ancestor had brown-eyed children, and they had brown-eyed children and so on until brown-eyed descendants who carried that gene got together and started producing blue-eyed children and then those blue-eyed children got together…?

I have blue eyes. I’m the product of two blue-eyed parents. However, three of my four grandparents had brown eyes. I have brown-eyed aunts and uncles. In my family just in the last two generations we show the results of chance in genetics. Both my parents just happened to get the blue-eyed gene from their parents. Then they could only pass on the blue-eyed gene…

Makes you think, huh? How has this played out in your family?