Biological Exuberance: Animal Homosexuality and Natural Diversity

(Gorilla gorilla beringei).” Primates 28:1-30.

*———(1987b) “Male Life History and the Social Structure of Wild Mountain Gorillas (Gorilla gorilla beringei).” In S. Kawano, J. H. Connell, and T. Hidaka, eds., Evolution and Coadaptation in Biotic Communities, pp. 31-51. Tokyo: University of Tokyo Press.

IDENTIFICATION: A medium-sized ape (adult males generally weigh around 170 pounds) with a long, reddish brown coat; some older males develop prominent cheek pads or “flanges.” DISTRIBUTION: Sumatra, Borneo (Indonesia); vulnerable. HABITAT: Swamps, lowland and mountain rain forests. STUDY AREAS: Ketambe region of North Sumatra, Indonesia, subspecies P.p. abelii, the Sumatran Orang-utan; Regent’s Park Zoo and Singapore Zoological Garden, including subspecies P.p. pygmaeus, the Bornean Orang- utan.

Social Organization

Adult Orang-utans are largely solitary—males and females live separate from each other and interact only when the female is ready to mate. Younger Orangs, however, are more sociable and may actively seek each other’s company and interact in groups. The mating system is polygynous: males copulate with multiple females and no long-lasting heterosexual pairing occurs, although males and females may “consort” together for shorter periods during mating. Males do not participate in parenting.

Description

Behavioral Expression: Orang-utans engage in a variety of homosexual activities, including a range of different sexual techniques and various affectionate and pairing behaviors. Mounting among male Orangs, especially younger adults (10-15 years old) and adolescents (7-10 years old) often develops into full anal intercourse, with erection of the penis, pelvic thrusting, penetration, and ejaculation. In a more unusual type of homosexual penetration, a male sometimes tries to insert his penis into the small hollow formed when his partner’s penis retracts. Another prominent homosexual activity is fellatio (oral- genital contact): one male will lick and suck another’s erect penis. In some cases, males take turns fellating each other. Males occasionally also fondle and touch the erect penis of another male, often examining the organ closely by parting the hairs in the genital region. Lesbian activity in Orangs usually involves one female fondling the genitals of another female, often inserting her fingers (thumb or other digits) into the vagina of the other. Sometimes she also masturbates herself with her foot while she is penetrating the other female. Mounting rarely, if ever, occurs among female Orangs, unlike in many other animals in which females engage in homosexual behavior. Female homosexual encounters may last for up to 12 minutes, comparable to the 10-15 minute duration of most heterosexual copulations. Although Orang-utans are usually willing participants in homosexual encounters, sometimes one animal is more reluctant and the partner will then attempt to restrain him or her, for example by using the feet to hold him or her down. However, this contrasts sharply with heterosexual encounters, in which females often scream and struggle violently while males attempt to forcibly mate with them (see the discussion on heterosexualities below).

Sexual behavior often occurs within a “bonding” or special friendship-like pairing between younger animals of the same sex. Two males or two females may become quite attached, following one another over several days, playing together (including play-wrestling), sharing food, and generally spending a great deal of time together and coordinating their activities. One partner may even throw a “temper tantrum” when the other ventures too far away or fails to wait for its companion. Female Orangs have also been known to compete with males for sexual access to a favorite female partner with whom they later develop a bonded relationship. Same-sex companions demonstrate a number of affectionate behaviors toward each other—females, for example, may embrace, cling to one other, walk in tandem, or groom each other, and males may “kiss” each other. While in some cases this mouth-to-mouth contact may be for the exchange of food or drink, in other cases it appears to be more of an affectionate or greeting gesture. Such companionships also develop between animals of the opposite sex, and indeed they resemble in many ways the “consortships” that sometimes characterize heterosexual mating relations. Companionships, however, need not involve any sexual contact, whether between animals of the same or opposite sex.

Fellatio in two younger male Orang-utans in Sumatra: the male on the lower right is sucking his partner’s penis

Homosexual interactions sometimes also occur between male Orangs and Crab-eating Macaques. These monkeys often associate with Orangs, feeding in the same areas and interacting nonaggressively. Orangs and Crab-eating Macaques may groom each other, and male Orang-utans will occasionally suck the penis of an adult male Crab-eating Macaque.

Transgendered Orang-utans occasionally occur as well: individuals have been found who are physically male yet have a female (XX) chromosome pattern.

Frequency: Approximately 9 percent of all Orang-utan sexual encounters in some populations involve males mounting each other; the proportion of same-sex activity is probably even higher, since male oral-genital contacts and female homosexual encounters are not included in this figure. Females who engage in lesbian activity may do so frequently and repeatedly over several days, similar to the repeated sexual interactions in a heterosexual consortship.

Orientation: Male homosexual behavior is characteristic of younger Orang-utans. Not all younger males engage in same-sex activity, but those who do are probably bisexual, since most such individuals are also involved in heterosexual pursuits. Mature adult males probably have a bisexual potential: although they rarely engage in homosexual activity in the wild, in captivity they often do (even in the presence of females). Female Orangs are probably also bisexual—for example, one female who was sexually active with another female later mated heterosexually and raised young. However, while engaged in homosexual behavior, she was exclusively lesbian, since she completely ignored males and focused her attentions entirely on other females.

Nonreproductive and Alternative Heterosexualities

A wide variety of nonprocreative heterosexual activities are found in Orang-utans. Both males and females often stimulate their partner’s genitals with their mouth or hands, and females may also rub their genitals against the male. The female has a prominent clitoris that is stimulated during intercourse, and she often takes the initiative in heterosexual activity, actually mounting the male, manually guiding his penis into her, and performing pelvic thrusts while he lies on his back. A variety of positions are used for heterosexual copulation, including face- to-face (the most common), front-to-back, and sideways. In almost 30 percent of mounts, vaginal penetration and/or ejaculation do not occur. Anal stimulation can be a component of heterosexual interactions as well: both males and females lick, suck, blow on, insert fingers into, and rub their genitals on their partner’s anus; males have also been known to engage in anal intercourse (penetration) with females. Females may consort and copulate with multiple male partners, and copulation can occur throughout pregnancy up to the time of birth. Masturbation is also common among Orangs—females rub their fingers or foot on their clitoris or insert a finger or toe into their vagina, while males rub their penises with their fist or foot. Both males and females also use inanimate objects or “tools” to masturbate. Males sometimes become sexually aroused and spontaneously ejaculate during long-calling (a courtship and territorial vocalization used by mature males). Mothers frequently engage in incestuous contact with their infants, manually or orally stimulating the penis or clitoris (or being stimulated by the infant), and may even mount the infants.

Heterosexual relations are sometimes characterized by aggression and violence rather than pleasure and consensuality. Younger males often chase, harass, and rape females. During such interactions, which may account for the majority of copulations in some populations, the male may grab, slap, bite, and forcibly restrain the female, who struggles violently while screaming or whimpering. Occasionally (about 7-8 percent of the time) she does