Biological Exuberance: Animal Homosexuality and Natural Diversity

Male Stumptail Macaques manually stimulating each other’s genitals. Mutual or reciprocal sexual behaviors such as this are good examples of homosexual activity that is not “dominance” oriented.

A final indictment of a dominance analysis is that the purported ranking of individuals based on their mounting or other sexual behavior often fails to correspond with other measures of dominance in the species. Male Giraffes, for example, have a well-defined dominance hierarchy in which the rank of an individual is determined by his age, size, and ability to displace other males with specific postures and stares. Homosexual mounting and “necking” behavior is usually claimed to be associated with dominance, yet a detailed study of the relationship between these activities and an individual’s social standing according to other measures revealed no connection whatsoever. Mounting position also fails to reflect an individual’s rank as measured by aggressive encounters (e.g., threat and attack behavior) and other criteria in male Crested Black Macaques, male Stumptail Macaques, and female Pig-tailed Macaques. In only about half of all male homosexual mounts among Savanna (Olive) Baboons is there a correlation between dominance status, as determined in aggressive or playful interactions, and the role of an animal as mounter or mountee. In male Squirrel Monkeys, dominance status affects an individual’s access to food, heterosexual mating opportunities, and the nature of his interactions with other males, yet the rank of males as evidenced by their participation in homosexual genital displays does not correspond in any straightforward way to these other criteria. Among male Red Squirrels, there is no simple relationship between aggressiveness and same-sex mounting: the most aggressive individual in one study population indeed mounted other males the most frequently, yet he was also the recipient of mounts by other males the most often, while the least aggressive male was hardly ever mounted by any other males. This is also true for Spinifex Hopping Mice, in which males typically mount males who are more aggressive than themselves. Similarly, although male Bison fairly consistently express dominance through displays such as chin-raising and head-to-head pushing, these behaviors do not offer a reliable predictor of which will mount the other. Although some mounts between male Pukeko appear to be correlated with the dominance status of the participants (as determined by their feeding behavior, age, size, and other factors), there is no consistent relationship between these measures of dominance and another important indicator of rank—a male’s access to heterosexual copulations (or the number of offspring he fathers). Finally, dominance relations in Sociable Weavers are not always uniform across different measures either: one male, for example, was “dominant” to another according to their mounting behavior, yet “subordinate” to him according to their pecking and threat interactions.⁹²

In fact, multiple nonsexual measures of dominance often fail to correspond even among themselves, and this has led some scientists to suggest that the entire concept of dominance needs to be seriously reexamined, if not abandoned altogether. While it may have some relevance for some behaviors in some species, dominance (or rank) is not a fixed or monolithic determinant of animal behavior. Its interaction with other factors is complex and context-dependent, and it should not be accorded the status of a preeminent form of social organization that it has traditionally been granted.⁹³ Primatologist Linda Fedigan advocates a more sophisticated approach to the role of dominance in animal behavior, eloquently summarized in the following statement. Although her comments are specifically about primates, they are relevant for other species as well:

We often oversimplify the phenomena categorized together as dominance, as well as overestimating the importance of physical coercion in day-to-day primate life … . An additional focus on alliances based on kinship, friendship, consortship, and roles, and on social power revealed in phenomena such as leadership, attention-structure, social facilitation, and inhibition, may help us to better understand the dynamics of primate social interaction. Also it may help us to place competition and cooperation among social primates in proper perspective as intertwined rather than opposing forces, and female as well as male primates in their proper perspective as playing major roles in primate “politics” through their participation in alliance systems.⁹⁴