Kin coalitions and social dominance

Abstract

Two models are presented which examine the relationship between dominance hierarchy and patterns of relatedness within social groups of animals: (1) a three-person game involving coalition formation; (2) a model of optimal compromise among conflicting self-interests. In both models, individuals are assumed to maximize inclusive fitness subject to constraints derived from both limitations on resources and the activities of other group members. Both models predict that closely related individuals will form coalitions to limit resource shares of less closely related individuals. They predict that in general a dominance hierarchy will result from two factors: (1) individual fighting ability; (2) coalitions among individuals more closely related to each other than they are to other group members. When all group members are equally closely related to one another (or all are unrelated), the latter factor will not be present; under these circumstances a greater proportion of the variance in dominance status should be explainable by differences in fighting ability than will be true when some group members are more closely related to each other than they are to other group members.