Fitness is a compound of many parts: ability to digest snippets, speed, parallelizability, etc.
Co-evolution and meta-evolution
Steady-state population model. Evolutionary Strategy (ES). Tournament matching. Brood crossover.
Homology is natural to the Monod genetic model, since programs appear natively divided into proteins. This does not mean that homology is necessary in the Monod model, but that its advantages can be used. This is in stark contrast to traditional approaches to Genetic Programming (GP), where the lack of homology causes, at least, great uneasiness about the crossover operator.