Eye colour

[chainfire]

Why is there different colours in humans and animals? Is there any difference between the colours or is there a reason (e.g. green can see better in the dark, etc)? Also why is blue a recessive allele compared to brown?
Sorry if the questions don't make any sence.
Thanks in advance.
-Chainfire

[lord molly]

blue is recesive because blue is recessive. nothing else to it

[gen2]

The colour of the iris has no effect on the vision of either humans or animals since light striking the iris does not enter the eye. On the other hand, if the person has a mutation that impairs the ability to produce certain pigments (eg melanin) then that can have an adverse effect on vision and the lack of pigment will also be noticed in the iris. In extreme cases, a total lack of melenin will give very poor vision and pink irises.

[gen2]

Blue is recessive because it is the result of a missing pigment. Any allele that instructs the cells to produce a pigment will have that colour present in the phenotype. Any mutation that disrupts that process will therefore fail to produce that pigment. If both alleles present are such mutations, then no dark pigment will be made in the iris and they will be blue.

[gen2]

There is more information here

[southerngirl]

On a documentary some years ago, about albinos, the guy doing the research said that brown eyes were best adapted to sunlight reflecting off the earth/sand etc and blue eyes for reflected light of f snow and ice. Not sure how that works with the Inuit though as I thought they had brown eyes. However, most blue eyed people live in northern europe where there is more snow and ice and you don't get blue eyed people naturally in Africa and Asia, so maybe the recessive gene found itself a use in northern europe.