Biological Exuberance: Animal Homosexuality and Natural Diversity

elaboration of homosexual behavior among our closest relatives in the animal kingdom will be led, eventually, to this conclusion. In fact, primatologist Paul L. Vasey traces the occurrence of homosexuality in primates back to at least the Oligocene epoch, 24-37 million years ago (based on its distribution and characteristics among contemporary primates).⁴⁹ Some of the most organized and developed forms of homosexuality among animals can be found in the more than 30 species of monkeys and apes where this behavior occurs. Bonobos, for instance, engage in both male and female homosexual interactions with disarming frequency and enthusiasm, and they have also developed many unique forms of sexual expression, including a type of lesbian tribadism known as genito- genital rubbing. Similar elaborations of homosexual patterns are found among Stumptail Macaques, Gorillas, Hanuman Langurs, and many other monkey and ape species. In addition to highly developed systems of same-sex interaction and diverse sexual techniques, a number of other aspects of homosexual activity in primates are particularly salient. Among these are various forms of pair-bonding such as consortships, “favorite” partners, or sexual friendships; evidence for exclusive or preferential homosexual activity in some individuals (as discussed in the preceding section); female orgasm in monkeys and apes, in both homosexual and heterosexual contexts; female-centered or matrifocal societies, as well as male alliances and other groups of cooperating males in some species; and the wide range of nonreproductive heterosexual activities found in many primates.⁵⁰

In addition to being part of our evolutionary heritage, homosexuality is also part of our cultural heritage as primates—for same-sex activity in monkeys and apes offers us some startling examples of cultural traditions among animals. Although “culture” is something that we typically associate with human beings, many animals innovate behaviors and then pass them on from generation to generation through learning. Zoologists speak of this as “cultural” behavior in animals—or, if the activity is less well developed, as “precultural” or “protocultural” behavior. Animal cultural traditions are widespread and often highly complex, occurring in many different kinds of species and involving behaviors as diverse as foraging and hunting techniques, communication patterns and song dialects, forms of social organization, response to predators, characteristics and locations of home sites and shelters, and migration patterns.⁵¹ Perhaps the most famous example of animal cultural behavior concerns food-gathering techniques in wild Japanese Macaques: in the mid-1950s, one female invented several ways of accessing novel food items (introduced by investigators), including sweet-potato washing, peanut digging, and “placer mining” for wheat. Within ten years 90 percent of all troop members had acquired these habits, which were being learned spontaneously by younger animals and passed on to subsequent generations.

“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.

Most of the hand signals are iconic, which means that they bear a physical resemblance to the meanings (i.e., body movements) they represent, although some are less transparently representational than others. Thus, the meaning “Turn your body around” can be related to the circular movement of the corresponding gesture, but this meaning is also conventionalized, since the intended action conveyed by the gesture must be agreed upon and understood by both participants for the gesture to be effective. An individual who hasn’t learned the gestural system, for instance, wouldn’t necessarily know what sort of “turning around” is intended by such a gesture. In conjunction with these hand gestures, a variety of positioning movements involving direct touching and placement of a partner’s body or limbs are also used to facilitate sexual interactions. Together with the more abstract manual gestures, a total of at least 25 signals used during sex have been identified. In addition, patterns of eye contact and gaze also appear to have significant communicative value.

DESCRIPTION: Arm is partially extended, hand flicks back and forth with sideways movement from wrist

MEANING : “Move your genitals around”—used to get partner to position his or her genitals to facilitate a sexual interaction

DESCRIPTION: Arm is extended, hand bends at wrist and makes rapid, vigorous circular motions

MEANING: “Turn your body around”—also used as an invitation for a sexual interaction if other methods of initiation have not worked