Cellular automata are computers, similar to Turing machines. The main difference is that Turing machines use a one-dimensional tape, whereas cellular automata use a two-dimensional grid. The best-known cellular automaton is the Game of Life, which is a universal computer. It belongs to a family of cellular automata with 262,144 members. Playing the Game of Life generally involves engineering; that is, assembling a device composed of various parts that are combined to achieve a specific intended result. Instead of engineering cellular automata, we propose evolving cellular automata. Evolution applies mutation and selection to a population of organisms. If a mutation increases the fitness of an organism, it may have many descendants, displacing the less fit organisms. Unlike engineering, evolution does not work towards an imagined goal. Evolution works towards increasing fitness, with no expectations about the specific form of the final result. Mutation, selection, and fitness yield structures that appear to be more organic and life-like than engineered structures. In our experiments, the patterns resulting from evolving cellular automata look much like the spots on leopards and the stripes on tigers.