We have seen that aggression is not a unitary entity, but is rather composed of several different subtypes (Moyer, 1976; Valzelli, 1981). Nevertheless, old aggression can be categorized into three primary areas: predation, territoriality, and dominance. Phylogenetic regression theory assumes that these three parameters of primitive aggression, taken singly or in various combinations, accounts for most aggressive behavior in both animals and humans. In humans, however, the picture is complicated by the elaborating effects of social learning and culture, but it is not uncommon for persons to regress to predatory destructiveness, territorial insularity, or raw dominance-submission relations when adequately stressed or provoked.