The colorful canvas of the butterfly wing is an example of evolutionary innovation and adaptation. Compared with their ansestors, whose wings wore patterns of black, brown, and gray, the Lepidoptera (butterflies and moths) evolved a more varied palette of pigmentation.
I think it is very cool that they were able to evolve. For example, some butterflies use their bright colors to trick preators into thinking they are poisonous. The early butterflies could not do this.
