Evolution of Bit Strings II: A Simple Model of Co-Evolution

In this pap er we present the results of simple co-evolut ionary models that simulate the tempora l development of a populati on of interact ing bit strings . Each bit st ring is decoded into funct ional groups called "genes." The indi vidu als participate in a pro cedure similar to t he Darwini an principle, that is, random int eraction (in which the genes det ermine the fitness of an ind ividual) followed by det ermini stic select ion including random errors during reproducti on. We use three select ion models: selection by sorting and replacing, tourn ament selection, and energy flow. We compare t he result s for each mod el to t hose of a randomselection model to ensure t hat "emergent" (non-t rivial) features are really caused by evolut ionary pro cesses. T he influence of selection is clearly evident when comparing the age dist ributions of individuals and species to t hose of t he random-selection case . While t he age distribution of the individuals shows a systematic deviation from an exponential behavior in the select ion case, the species ages tend to follow a power law when applying non-random select ion . The species show a dynamic of "pu nct uated equilibria" that is similar to the behavior of natural systems.