How it may have developed. Note the comments about brain plasticity which brings up the issue of how does the brain learn to interpret new signals from the retina, if the retinal signals of color are suddenly changed by a mutation?-http://www.the-scientist.com//?articles.view/articleNo/41055/title/The-Rainbow-Connection/-"This suggested that the animals' brains were making use of the new opsin. “I think that's the cool part of it, that [plasticity] is just an intrinsic property of a sophisticated nervous system like a mammal's,” says Nathans."