A review of selected sociobiological principles: application to hominid evolutionI. The development of group social structure

In summary, weapons had the effect of making the hominid groups more closed, with an extremely well organized dominance-based social structure.

Abstract

The first section of this paper reviews sociobiological theories about: (a) Sex and Mating Systems, (b) Kin selection and Inclusive Fitness, (c) Aggression and Mechanisms of Control, and (d) Dispersal, focusing mainly on terrestrial primates and social carnivores. The second section deals with applications of these principles to hominid evolution. It is suggested that the early hominids, prior to the development of weapons, lived in groups similar in structure to present-day terrestrial primates, with slight modifications caused by selection associated with co-operative hunting. The groups were structured around a stable core of interrelated females with a fairly stable, dominance-based group of associated males. Male emigration was slightly reduced due to the need for male—male co-operation. The early hominids were probably polygynous. With the development of weapons, it became necessary to reduce the expression of aggression with the group. This was accomplished by: Decreasing or eliminating individual transfer between groups, thus increasing the number of adult males; Strengthening the dominance hierarchies and changing the determinants of dominance from physical to social and mental skills; Increasing the length of the females' estrous periods, thereby reducing the males' benefit per copulation and the need for male—male competition. As a result, male—female mating ties become stronger and more long-lasting; and Developing in females as appeasement signals characteristics which mimicked off-spring and mothers. These characteristics, being fitness-related, eventually became attractive to the male and were sexually selected. In summary, weapons had the effect of making the hominid groups more closed, with an extremely well organized dominance-based social structure. Only the more dominant males remained polygynous, with semi-permanent mating ties to several females. Some subordinant males were able to mate, and when they did so, were probably monogamous.