Cooperation, Coalition, and Alliances

Abstract

In primates, cooperative acts have been observed such as communal rearing of offspring, cooperative mobbing of predators, supporting others in fights, and grooming others. Grooming builds up a social bond between the partners, helps in repairing relationships, and produces all kinds of benefits for the groomee, such as the reduction of parasites, and of tension. Although the costs for the groomer are low, it has been regarded as an altruistic act and therefore is expected to be preferably directed toward kin or to be repaid by being reciprocated or exchanged for another service (e.g., support in fights, help in rearing offspring in the case of communal breeding systems, or access to some object, such as food, or some individual such as a female, an infant, or members of another group). The formation of coalitions may result in the maintenance or the increase of the dominance of an individual, in the expulsion of certain individuals from a group, in taking over a group, in the defense of the home range against other groups, in getting access to estrus females, and in the protection of an infant or adult female. The degree of cognition involved in coalitions is unclear. Which members of a group cooperate differs from species to species; it may be influenced by genetic relations, by the size and the composition of the group (the sex ratio), the degree of competition, and by the distribution of food.