Simple feather patterns can be predicted using mathematical models called Turing reaction-diffusion equations. As a feather grows, each new cell must decide whether it will receive pigment or not, depending on the pigmentation of its neighboring cells and overlapping chemical gradients. The feather patterns of the Great Argus Pheasant are among the world's most complex. We don't have the math yet to model them, but now we know something of how these amazing patterns self-organize. This program was filmed at the Harvard Museum of Natural History.