Ever since Darwin, evolutionary biologists have sought to use human-driven evolutionary change as a model for understanding organic evolution. Some of the most profound and rapid changes in character evolution have been driven by farmers, enthusiasts, and plant and animal breeders using artificial selection to modify the phenotypes of hundreds of domesticated species. This type of intense and focused selection has invariably altered the genomes of domesticated species, affording us both an opportunity for understanding patterns of genetic variation in species subject to intense selection as well as the raw material from population samples for identifying genes of large phenotypic effect.