J. F. Eisenberg The University of Florida, Gainesville
I believe we are concerned in this symposium with complex social organizations and thus may disregard aggregations which show only limited coordination and integration. Integrated social organizations are characterized by the following attributes: The members have a complex system of communication; they often have a division of labor based on specialization for role; and the members show a cohesion or tendency to remain together. Some groups may show seasonal changes in composition. In highly social forms a member may be involved with the same set of adult companions for its entire life. Finally, there is a tendency for the group to be relatively impermeable to nonrelated conspecifics ( Eisenberg, 1966).
Because of the unique mode of neonatal nutrition in mammals, namely that only the female lactates and the young are nourished by milk, the bulk of parental care falls to females and often the most cohesive social unit in a mammal society is that composed of a mother and her young. In long-lived species this grouping can be expanded into a unit involving a mother and several age classes of young. Where daughters remain with mothers and males leave, a matriarchy may be formed. The only advance possible beyond this stage of sociality is the inclusion of an adult male in the group as a provisioner or protector of the female-neonatal