Danny Hillis' genetic algorithm experiments with his Connection Machine led to his formulating the Red Queen Hypothesis. Basically it is a coevolutionary model. GAs traverse a fitness space and find maxima in that space; and the problem, as Hillis observed, was that genetic algorithms/systems have the propensity to get stuck at a local maxima. It makes perfect sense in hindsight, if you think about it. To remedy the situation, he introduced another GA type (a 'parasite' species) to compete with the original type. The introduction of the predators destabilized the system and provided impetus for the original type to actually descend from a local peak and thus (possibly) find a better relative (or possibly absolute) maxima in that space. These flies were isolated. The system was homogeneous. The longer hair and more eggs are a local maxima.