Biological Exuberance: Animal Homosexuality and Natural Diversity

As a matter of fact, in most instances both heterosexual and homosexual acts are equally “uninspired,” involving nothing more exotic than mounting behavior in the front-to-back position typical of mating in most animals. Even considering animals where other mounting positions are used, however, it is overly simplistic to claim that same-sex activity involves more “versatility.” In many species a variety of positions are employed in both heterosexual and homosexual situations. Furthermore, even though their frequency of use differs depending on the context, the major distinctions in mounting positions often lie along lines of gender rather than sexual orientation. The differentiating factor is not whether sexual activity involves partners of the same or opposite sex, but whether it involves males (in either heterosexual or homosexual contexts). For example, a face-to-face position is used for roughly 99 percent of sexual interactions between female Bonobos, but rarely in male-female interactions. However, a face-to-face position is almost equally rare in male homosexual interactions, occurring in only about 2 percent of activity between males. Thus, male homosexuality is more similar to heterosexuality than either is to female homosexuality in terms of the frequency of use of these two basic positions. A similar pattern occurs in Gorillas: although the face-to-face position is virtually absent in heterosexual encounters and much more common in homosexual ones, the two sexes have almost opposite preferences for this position. Almost three-quarters of female homosexual encounters involve the face-to-face position, while more than 80 percent of male homosexual mountings involve the front-to-back position (also preferred for heterosexual encounters). In Hanuman Langurs, male homosexuality is also more similar to heterosexuality than is female homosexuality in terms of the way that interactions are initiated: both males and females typically invite males to mount them by performing a special “head-shaking” display, which is much less characteristic of mounting between females.⁴⁴

In Japanese Macaques, female homosexuality is more similar to heterosexuality than to male homosexuality in terms of the variety of positions used. In contrast, male homosexuality is more similar to heterosexuality than female homosexuality in terms of the frequency that various positions are used. In this species, fully seven different mounting positions can be identified, including four varieties of the front-to-back posture (with the mounting animal sitting, lying, or standing—with or without clasping its partner’s legs—behind the mountee), two types of face-to-face positioning (sitting or lying down), and sideways mounts. All seven of these positions are found in both heterosexual and female homosexual encounters, while male homosexual mounting employs only five of the seven (sitting or lying on the partner in a front-to-back position are not used). However, sexual encounters between females differ from both heterosexual and male homosexual mounts in using the face-to-face position more often, and in using the double-foot-clasp posture less than 20 percent of the time (compared to 75–85 percent of the time for sexual encounters where males are involved, either heterosexual or homosexual).⁴⁵

Other patterns based on the intersection of gender and sexual orientation also occur. In Stumptail Macaques, for example, female homosexual encounters use three basic positions (standing or sitting front-to-back and sitting face-to-face), heterosexual activity uses two of these (standing or sitting front-to-back), while male homosexual activity uses only one of these (standing front-to-back). (Males do, however, employ a wider range of oral and manual forms of genital stimulation in their encounters with each other.) Copulations between female Flamingos generally resemble heterosexual matings more than they do mountings between male Flamingos, but same-sex copulations in birds of either sex differ from heterosexual activity in their lack of a particular “hooking” posture.⁴⁶ Male White-handed Gibbons interact sexually with other males only in a face-to-face position and with females only in a front-to-back position—thus, homosexual and heterosexual interactions are equally “flexible” or “inflexible” in this species, but differ in which position is preferred in each context. Even reciprocal or reverse mounting—in which partners take turns mounting each other—is part of the heterosexual repertoire in more than three-quarters of the species that engage in this activity (in either same-or opposite-sex contexts); it is unique to heterosexual relations in many of these (including Western Gulls and Silvery Grebes) and present in many animals that do not engage in homosexual behavior at all.