Blue eyes origins

[The_simpsons]

Recent findings suggest blue eyes arose from a mutation in some melanin-controlling gene 6000 - 10000 years ago in a population that lived close to the black sea right?

And then it spread from there.

But how did that recessive trait suceed to spread so well?

Im wondering if it was of sexual selection (that it was merely an pysically attractive trait), luck or practically benefiting in survival (i.e improved vision)?

A guy i know argued that blue eyes arose in these more northern people because there is less sunlight, and blue eyes are better at absorbing light, so he was quite certain it came about of practical reasons.

Personally i didn't quite agree, since when did blueeyed people have significanly better vision in darker areas than browneyed people, enough to aid in survival?

That was my thought, i always found it more likely to be because of increased sexual attrativeness or because of a chance event (a successful individual gets the mutation, and also reproduces succesfully indepently of the trait, and the trait just tags along).

 

So folks, what's your opinion concerning why a blue iris came to be so sucessful?

[Mr Skeptic]

It seems blue-eyed men are attracted to blue-eyed women (but not the other way around). Since blue eyes is a recessive trait, any children he has with her are guaranteed to be blue eyed, and any children that are not blue eyed are guaranteed to be someone else's. I doubt that was the only reason though.

[iNow]

Who says that blue eyes offered an advantage? Maybe they are linked to some other trait which does. Not all features present in the population were directly selected for. Sometimes, they are just emergent properties tied to other characteristics which were selected.

[jimmydasaint]

Who says that blue eyes offered an advantage? Maybe they are linked to some other trait which does. Not all features present in the population were directly selected for. Sometimes, they are just emergent properties tied to other characteristics which were selected.

 

Agreed. However, I don't think the Mendelian inheritance of blue eyes is a simple Mendelian trait and may involve some multi-gene epistasis. That is only an opinion because I am too tired to look for a link right now.

[Snare]

Blue (or lightly colored) eyes don't seem to offer much of an advantage.

 

I know an individual with "seafoam" colored eyes. His mother has the same trait. He has to wear sunglasses in intense sunlight otherwise he has a hard time seeing. Perhaps it might be an advantage in areas with lower levels of sunlight, but in my (amateur) opinion it appears to be something that developed as a result of the fact that there is less sunlight in northern environments and thus the trait was not much of a hindrance.

[SkepticLance]

There was a snippet on this in New Scientist some months back. They agreed with the mutation idea, and suggested that the recessive gene became so common due to sexual selection. Remember the song? "Beautiful, beautiful blue eyes."

[Geshenk]

I think it may be more to do with vit D synthesis. Eye colour is linked with skin colour and those with light skin and eye have a selection advantage in climates with reduced sunlight as they can better synthesize the vitamin.