Biological Exuberance: Animal Homosexuality and Natural Diversity

“Culture” can also involve social behaviors: male caretaking of infants in Japanese Macaques, for example, is characteristic of only certain populations and appears to be a learned behavior, acquired by some individuals or troops and not others. Sexuality—including homosexual activity—can also bear the hallmarks of cultural activity. Scientists studying mounting behavior by females—once again in Japanese Macaques—suggest that whether and how females mount male or other female partners may represent a form of protocultural behavior. Certain mounting positions, for example, seem to become more “popular” in some troops over time, only to wane and be replaced by others. Likewise, masturbation among females appears to be learned through observation or other social channels. Although a capacity for homosexual activity (along with reverse mounting and masturbation) is probably an innate characteristic of the species (as evidenced by at least some level of these activities in most populations), its occurrence between different troops and individuals is highly variable. Key aspects of such activities are apparently being learned and passed on through space and time. This indicates that “traditions” or patterns of sexual activity may be innovated and then transmitted via a web of social interactions, moving between and within population groups, geographic areas, and generations. Sexuality, including aspects of both same-sex and opposite-sex interactions, is also considered to exhibit aspects of cultural traditions in at least two other primates, Stumptail Macaques and Savanna Baboons.⁵²

Not only is sexuality itself a form of cultural behavior, it can also impact and intersect with other sorts of cultural innovations in primates, often in surprising ways. In fact, nonreproductive sexual activities, including homosexual behaviors, may have contributed to the development of a number of significant cultural “milestones”: hallmarks of evolutionary and cultural change that are considered to be defining characteristics of “humanness,” yet which also exist in prototypical form in some of our primate relatives (and presumably also in our protohuman ancestors). In this section we’ll briefly consider the role that sexuality might have played in the development of primate communication systems and the origin of language, in the manufacture and use of tools, and in the creation of social taboos and rituals. Caution must always be exercised in making direct comparisons between animals and people, and most of these areas are only beginning to be studied in any detail. Nevertheless, primate (homo)sexuality and the “traditions” associated with it offer us a striking mirror of some of our most “human” characteristics—and perhaps even a window into our evolutionary past and cultural history.

Language

Bonobos (also sometimes known as Pygmy Chimpanzees) have one of the most varied sexual repertoires of any species, with a wide variety of behaviors and positions used in sexual interactions, both heterosexual and homosexual. As a result, some Bonobos have developed an extraordinary system of gestural communication that is used specifically during sex. First discovered by pioneering ape-language researcher Susan Savage-Rumbaugh and her colleagues in the mid 1970s, this gestural system has far-reaching implications for our understanding of primate communication systems and the development of human language.⁵³

A “lexicon” of about a dozen hand and arm gestures—each with a specific meaning—is utilized by Bonobos to initiate sexual activity and negotiate various body positions with a partner (of the same or opposite sex). For example, one gesture involves flicking the hand back-and-forth sideways from the wrist, meaning (approximately), “Move your genitals around”; this is used to get one’s partner to position his or her genitals so as to facilitate a sexual interaction. Another gesture, lifting the arm with the palm downward, is employed when a Bonobo wants a sexual partner to move into a facing position for copulation. A catalog of some of the other gestures is given in the accompanying illustration. Hand signals may even be strung together in short sequences, and there is some evidence that the order of the gestures is significant.⁵⁴ These manual signs are used during both heterosexual and homosexual activity, although it appears that they may be more prevalent in opposite-sex interactions, and males and females may also employ some of the gestures with different frequencies.