Biological Exuberance: Animal Homosexuality and Natural Diversity

The precise opposite of the “standard” dominance-based system of mounting is often found as well: mountings by subordinates on dominants occur more frequently than the reverse in many species. In Crested Black Macaques, for example, 60—95 percent of mounts are subordinate on dominant, while nearly two-thirds of Bison male homosexual mounts are by subordinates on dominants. To complicate things further, this is often combined with a gender difference in the relationship between mounting and dominance, with female mounts “following” the hierarchy and male mounts going “against” it. For instance, in Pig-tailed Macaques mounting between females is usually by a dominant individual on a subordinate one, but more than three-quarters of mounts between males are just the opposite. Similarly, in both Red Deer and Pukeko, females tend to mount lower-ranking animals while males tend to mount higher-ranking ones. There are often individual or geographic differences as well: in some consortships between female Japanese Macaques, all mounting is done by the lower-ranking individual on the higher-ranking partner, while in some populations of Bighorn Sheep, mounting of dominant rams by subordinates is much more prevalent than in other populations.⁸⁰ Furthermore, homosexual mounting in many species is reciprocal, which means that partners exchange positions—mounter becomes mountee, and vice versa—either in the same mounting session or in alternation over longer periods of time. This behavior, which is found in at least 30 different species, is potent evidence of the irrelevance of dominance for homosexual interactions, since mounting should only occur unidirectionally if it strictly followed the rank of the participating individuals.⁸¹ Finally, in some species mounting can also occur between individuals of the same or close ranks—for example, in Common Chimpanzees, White-faced Capuchins, Musk-oxen, Blackbucks, Cavies, and Gray-capped Social Weavers.⁸²

In a dominance-based view of homosexual mounting, it is often assumed that the animal being mounted is somehow a less willing participant in the interaction, “submitting” to the will of the more dominant individual, who thereby asserts his or her “superiority.” In fact, in more than 30 species the mounted animal actually initiates the interaction, “presenting” its hindquarters to the other individual as an invitation to mount, sometimes even actively facilitating anal penetration (among males) or other aspects of the interaction. Where the presenting animal is subordinate, this could be interpreted as simply a reinforcement of the dominance system, but in a number of species it is actually the more dominant individual who presents and actively encourages the lower-ranking animal to mount.⁸³ In addition, dominance “explanations” often ignore the clear differences between consensual and nonconsensual mounts (or rapes), as well as evidence for sexual arousal and even enjoyment on the part of mounted animals.⁸⁴

The relationship between sexuality and dominance is complex and multifaceted, differing greatly from the frequent simplistic equating of homosexual mounting with nonsexual rank-based or aggressive behavior. In many species a gradation or continuum exists between sexual mounts and dominance mounts, with one type “blending” into the other so that any distinction between the two is essentially arbitrary. Thus, same-sex mounting can have an unmistakable sexual component even when it still follows a dominance pattern. Among Hanuman Langurs, for example, usually only dominant females mount subordinate ones, yet so inextricably linked are signs of sexual excitement with this behavior that scientists have concluded, “It seems virtually impossible to separate ‘sexual mounting’ from ‘dominance mounting.’ … Sexual arousal and dominance are obviously not mutually exclusive in langur females, since mounting between females is related to both dominance and sexuality.”⁸⁵ At the other end of the spectrum, in some species a sharp distinction does in fact exist between two types of mounting, both of which occur between same-sex partners: a nonsexual form associated with dominance and/or aggression, and a clearly sexual form that occurs in other contexts (often within a homosexual pair-bond or consortship). This is true for female Japanese Macaques, Rhesus Macaques, and Black-winged Stilts, and male Greylag Geese, among others.⁸⁶