How do green and hazel eyes occur?

Question

I've recently read an article that states blue eyes happen(ed) because of a deformity that causes the brown pigment to turn off or something along those lines. Apparently we "all originally had brown eyes." So I'm curious how other eye colors occur?

Answer 1

http://www.youtube.com/watch?v=zCXNsaiiT...

Answer 2

It's all genetics.

Answer 3

You are correct, the original ancestor of humans very likely were homozygous dominate (having two dominate genes -- allele) for brown eye color.  Blue and green eyes came about because mutations (and environmental factors -- natural selection) causing one of the two dominate genes to take on a recessive nature.  It turns out that according to Mendelian inheritance, when two of these recessive genes are transmitted to an offspring, the offspring's eyes are not brown but some other color, generally blue.

Now non-dominate eye color (other than brown) can be pretty variable in color tent as a function of gene expression and environmental factors.  Green eyes is the result of something called "incomplete dominance".  The gene for brown eyes does not completely dominate the recessive gene for blue eyes --- green results.

See: http://en.wikipedia.org/wiki/Autosomal_r...

  

Answer 4

Your father would have to be Kermit the Frog!