To simulate natural selection in an interesting way in the computer ... we should concentrate ... upon simulating non-random deaths. Biomorphs [computer generated animal-like graphics following a defined logic of 'evolution'] should interact, in the computer, with a simulation of hostile environment. Something about their shape should determine whether or not they survive in that environment. Ideally, the hostile environment should include other evolving biomorphs: 'predators', 'prey', 'parasites' 'competitors'. The particular shape of a prey biomorph should determine its vulnerability to being caught, for example, by particular shapes of predator biomorphs. Such criteria of vulnerability should not be built in by the programmer. They should emerge in the same way as the shape themselves emerge. Evolution in the computer would then really take off.

If anybody is clever enough to do it, it would be the programmers who develop those noisy and vulgar arcade games - Space Invaders' derivatives. ... But these programs are small-fry compared to the program that would be written to simulate an emerging arms race between predators and prey, embedded in a complete, counterfeit ecosystem. ... If there is a professional programmer out there who feels like collaborating on the challenge, I should like to hear from him or her.