Human Evolution: Biology, Technology, Culture

Evolution for all animal species occurs at the biological level. When gametes undergo meiosis, chromosomal crossover that occurred in the parents' gonads ensures that offspring are significantly varied while retaining the basic traits of their progenitors. Some species are social, and they may well undergo nuanced cultural evolution which makes things like the dolphin version of rape more or less acceptable among larger groups of dolphins. I am not sure if this actually occurs, but one can certainly imagine that it might occur.