Baby Blue Eyed Freaks

What does Liv Tyler, Rachel McAdams and Ryan Phillipe have in common?

They are all blue-eyed mutant freaks according to LiveScience.

The Natural color of human irises range from brown, the most common, to blue, which lack pigment. The gene that dictates the color of our eyes also affects hair and skin color. This is why we associate blue eyes, blonde hair or green eyes and red hair.

However, scientists have shown that a genetic mutation is common in all blue eye owners. This mutation is not in the hair-eye-skin color gene itself (technically called OCA2), but in the gene next to it. It then affects OCA2, by literally turning our brown eyes, blue by lessening the amount of pigment in the eyes. This isn't to say that the mutation turns off OCA2; if it did, we'd be albino because we'd have absolutely no pigment.

Illustration:

[neighboring gene]-[OCA2]=unaffected OCA2=pigment=big browns O_O
[mutated neighboring gene]-[OCA-2]= affected OCA2=lesser pigment= baby blues O_O
[somehow messed up OCA2] = turned off OCA2=no pigment at all=crap. you are albino O_O


Now how did they figure this out? Scientists took a bunch of blue-eyed people from all over the world and looked at their mitochondrial DNA, which only comes from your mom. You can imagine that over hundreds of generations, the DNA would have some kind of natural variation in it. However, 799/800 blue eyed people had the same mutation in the same unchanged region of DNA (the 800th person had blue eyes with a brown spot). This means the mutation for blue eyes must be genetically recent--it hasn't been around long enough for variation to be introduced. Also, since all these people share the same region of DNA, there most be a common ancestor...that arose 6-10,000 yrs ago. Scientists imply that before this time, blue eyes simply didn't exist.