How does variation in genes generate the beautiful diversity of animal body shapes that fill the world? A series of bizarre mutations in fruit flies led to the discovery that all animals, whether fish, fowl, or fly, share similar architectural control genes called Homeobox genes. These genes instruct early embryos to develop eyes in the head, appendages in the middle, and excretory and sexual organs in the rear. They provide a pattern that evolution can build on to construct organisms of incredible diversity, beauty and complexity. The discovery and study of Homeobox genes has opened a new and beautifully complex window into the development of new life and has led to an understanding of how subtle changes in Homeobox genes can lead to changes in animal form during evolution. Most satisfying, they have revealed a deep and profound kinship between all species, no matter how different they appear on the outside, that was invisible until biologists began to study the genes that control embryonic development.