Also robin's eggs -- have that sky blue shade. Note that I was using "blue" as an example of a natural selection force. We also have the blue-skinned mountain families of the western Virginia. Sky blue is considered by many as a pretty color. Why aren't more female humans sky blue?
Wouldn't the affinity for pretty blue be a selection force? Why haven't the blue-skined mountian folks propagated more?
Are they the melugeons? I remember reading something about them but I forgot what it was.