Blue-eyed humans have a single, common ancestor

[Celebration]

http://www.physorg.com/news120933651.html

Originally, we all had brown eyes”, said Professor Eiberg from the Department of Cellular and Molecular Biology. “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. 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.

[gateley]

1. Jesus. I've seen pictures. nt

[livvy]

2. Thankfully, I am chewing gum instead of drinking anything.

A wad of gum is easily removed from my monitor. A mouthful of soda would not have been so easy to remove.

Too funny...good one, gately!

[Celebration]

4. here is the purpose of this

Teach high school kids genetics--recessive vs. dominant genes.

You remember--

Two blue eyed parents and the kid has blue eyes. This one is easy.

One brown and one blue eyed parent-- 50% chance of blue or brown eyed kid, well it depends if the brown eyed parent has a recessive blue eyed gene. If two dominant brown eyed genes in one parent all the kids have brown eyes.

Two brown eyed kids--DON'T ASK

[Igel]

12. Wouldn't that be humorous.

"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."

Palestine's not so far from Jordan, and we know that there's been a lot of population movement in the last 2k years, some from the northwest and a lot more from the south and southwest.

On the other hand, they don't say the probability of the blue-eyed folk in Jordan having blue-eyed ancestors that date way back, to 3-5k before present. They could have come in from western colonialism, or the more numerous Slavic slaves that were all the rage for hundreds of years, or some of the Ottman Empire's politically-inspired mass relocation programs. Or they could have been dispersed 6k BC.

[eleny]

3. what if you have green eyes rimmed in blue?

that's what i've got. there's always more questions!

thanks for the article. i have lots of family with blue eyes. so this is very interesting. i think my mom was the only one who had brown eyes.

[progressive_realist]

5. Heh. Heh.

If both her parents had blue eyes, then Granddad isn't really Granddad.

:evilgrin:

[eleny]

11. Mom's dad had brown eyes and her mom had blue

Phew!

[Vadem]

8. Eleny, your eyes sound beautiful and very unusual.... you should

post a picture so we can see your very unusual irises. I've never heard of green eyes rimmed in blue! (I have blue eyes, my sister has green eyes and my brother has brown eyes!)

[eleny]

10. Your family is all mixed up like mine!

I always envied my maternal gram and my brother for their blue eyes.

I bet if everyone took a really close look at their eyes they'd be amazed.

[progressive_realist]

6. That means the first blue-eyed person was inbred.

The person who originally got the mutation had brown eyes (1 blue + 1 brown gene). All of that person's children also had brown eyes (half the offspring had 1 blue + 1 brown; the other half had 2 brown genes). Only if two of that person's descendants bred (both carrying the recessive gene) would blue eyes ever show up in the population.

[Occulus]

7. Don't it make my brown eyes blue n/t

[Geoff R. Casavant]

9. Heck, that's nothing.

Read Richard Dawkins's The Ancestor's Tale, where he discusses his concept of the "concestor," the individual who is the most recent common ancestor of any given subset of organisms.

For example, according to calculations by population geneticists, the concestor of all humanity lived in Asia a mere 3500 years ago. I think that may have been a misprint and 35,000 years ago is what they meant, but I haven't yet confirmed this.

In fact, based on the similarity of DNA across all known forms of life, you can just as easily say all life arose from a single, common ancestor, if you're willing to look back far enough.