Why are our eyes colored?

Why do we have colored eyes?

• Why is the iris coloured in blue, green, black or brown? Since every evolution has a purpose (we have legs to walk, we have voice to communicate), what is the purpose of colored eyes?

• Answer:

  Brown/black eyes are the normal, functional phenotype. Pigments in the eye are meant to block out and absorb excess light from entering the eye, making your vision clearer and protecting you retina from excessive light that can theoretically damage the eye. When the gene encoding the pigment is mutated, the resultant failed protein has a distinct color depending on the nature of the mutation. Since the coloration is not so incredibly important in survival, the selective pressures that might eliminate such mutants normally do not act to eliminate the faulty gene from the gene-pool--especially in places like Northern Europe, where sun light is far less destructive than it is in southern/equatorial latitudes. Additionally, there may be a degree of sexual selection that enhances the degree of blue eyes, if one could establish that blue eyes were seen as favorable in any ancient European sociaties. Some reaon the tendency for fair eyes in those places as being, in women, a trait that affects a more youthful appearance. Since babies are generally born without functioning/activated eye pigmentation, and such pigments come forth only later in life, darkening the eyes, it is reasoned by some that blue eyes tend to give a youthful appearance, with youth being traditionally linked to fertility. there is no hard data that can back this claim up, but it is reasonable that such a process could work within the scope of known evolutionary mechanisms.