Maybe it also helped keep population down.
But, no one has ever been able to explain this to me...
If people with blue eyes reporduced at the same rate as homosexuality, how long before the blue-eye gene died out, and why doesn that exttinction then apply to homosexuality?
It wouldn't die out even if every blued eyed person who is ever born is prevented from procreating.
The genes that dictate blue eyes are recessive, so it is often dormant within the brown-eyed populations.
For example, my father has blue eyes. I have brown eyes. I know I carry the genes necessary to have a blue eyed child becuae that is all I could receive from my father.
The same is true for my wife.
If we assume there are only two genes involved with this trait (there are more, but for the illustation,m we'll just go with a mendellian genotype comparison)
B = brown eyed gene, b = blue eyed gene, both my wife and I have the genotype of Bb.
We a phenotypically brown-eyed, though, because B is dominant.
So when we have children, we each will either pass on a B or a b.
Out of four children ,the genotypes possible are BB, Bb, bB, and bb.
Of these four combination, three will be phenotypically brown eyed: BB, Bb, and bB.
One will have blue eyes: bb.
So while our children have a 75% chance of having brown eyes, they actually have a 75% chance of carrying the gene for blue eyes.
50% of our children would have the chance to be brown eyed with the blue eyed gene so that they don't display the blue eyed trait, but carry on the genes.
If I was breedig with a woman who was genotypically BB, teh results would be:
BB, Bb, BB, and BB
In that case, all children would have brown eyes, there is only a 25% chance that each one would carry the blue eyed gene.
If I was breeding with a woman who was bb the results would be:
bB, bb, bB, bb.
All children would carry the blue-eyed gene, and there would be a 50/50 chance for either eye color.