THE EVOLUTION OF SELF-REPLICATING COMPUTER ORGANISMS

A computer model is described that explores some of the possible behav ior of biological life during the early stages of evolution. The simul ation starts with a primordial soup composed of randomly generated seq uences of computer operations selected from a basis set of 16 opcodes. With a probability of about 10(-4), these sequences spontaneously gen erate large and inefficient self-replicating ''organisms''. Driven by mutations, these protobiotic ancestors more efficiently generate offsp ring by initially eliminating unnecessary code. Later they increase th eir complexity by adding additional subroutines as they compete for th e system's two limited resources, computer memory and CPU time. The en suing biology includes replicating hosts, parasites and colonies.