Male Bonds: Afilliative Relationships Among Nonhuman Primate Males

A deductively obtained model concerning the factors that determine male social relationships within the framework of primate social organization is discussed in the light of existing empirical evidence. Tolerance and affiliative bonding are expected to occur less easily between male than between female primates. Whereas females compete for resources such as food, males, in addition compete to obtain fertilizations. Unlike food, fertilizations cannot easily be shared. This undoubtedly hampers the formation of male coalitions and the development of male bonds. Indeed, male tolerance tends to be low especially in species where the spatial and temporal distribution of females is such that individual males may monopolize access to such females, thus facilitating inter-male contest. Nevertheless there are a number of species in which tolerance between adult male group members is remarkable. In some cases forms of coordination and mutual attraction exist that justify the qualification of 'male bonding'. An important factor supposed to conduce to the development of male bonding is the inclusive fitness benefit that support and tolerance between male relatives may bring. This would occur especially where circumstances permit male philopatry. The latter is expected in species where the nature of female competition for basic resources does not lead to strong female-bondedness and female nepotism, allowing females to become allopatric. There is evidence from various species that related males form bonds under the mentioned conditions. A special case of this is the formation of father-son bonds, noted in species with strong intermale contest and corresponding sexual dimorphism. A remarkable alternative, by the way, is the existence of mother-son bonds which last into adulthood and which contribute to a male's position. There are indications for such bonds in two species where males stay with their mother and where sexual dimorphism is low. Still kinship clearly is not a necessary factor for the development of male tolerance and of support between males. The factor does not play a role, for instance, in the short-term coalitions found in baboons. Here opportunism based on mutual or reciprocal benefits seems to play a decisive role. The evidence presented lends support to the idea that there is an order of priorities, in which, first, socioecological factors determine the spatial, hierarchical and affiliative relationships between females. These female relationships then set the scene for the males, in that these determine the options left open for the males to organize their patterns of competition, migration and bonding.