Bruce Bagemihl - Biological Exuberance

Orientation: Depending on the population, 20–90 percent of females participate in homosexual mounting and/or consortships. The majority of these females are bisexual, since they also engage in heterosexual activity (either concurrently or during other periods of their lives), and some even alternate between same-sex and opposite-sex activities in the same day. At least some females that are bisexual nevertheless do seem to prefer homosexual activity, since they return to their female consorts even after having mated with males; a female consort may also try to “win” her female partner back whenever she is temporarily with a male. In addition, some individuals participate in lesbian consortships more frequently than others and generally have much less contact with the opposite sex. Females may also be generally more receptive to same-sex advances: in one population, for example, only 6 percent of attempted homosexual mounts were rejected, compared to 29 percent of heterosexual attempts. Many male Rhesus Macaques are bisexual as well, and individuals vary in their participation in homosexual versus heterosexual activity. As with females, though, some individuals do seem to show a “preference” for homosexuality, since males may mount each other while ignoring available females. Moreover, in a detailed study of one male homosexual consortship or sexual “friendship” in captivity, both males preferred each other’s company to that of a female and chose each other as sexual partners when given a preference test (even though both were able to perform heterosexually with a female).

Rhesus Macaques are noted for their nonprocreative heterosexual behaviors. Half or more of all pregnant females engage in sexual behavior (including mating), and 12 percent of all copulations involve pregnant females. Some individual males even seem to prefer mating with females after they conceive, since nearly half of their copulations are with pregnant females. In fact, parturition itself sometimes stimulates sexual activity in attendants and onlookers, who may masturbate themselves or even mount the mother shortly after she gives birth. More than 40 percent of menstruating females also engage in sexual activity. The typical pattern for heterosexual copulation includes a large number of nonreproductive mounts, since the male may mount the female up to 100 or more times as part of each “copulation.” Although penetration may occur during each mount, usually only the final mount in the series involves ejaculation. Females often initiate sexual behavior with males and commonly experience orgasm during heterosexual mating. They may also copulate with several different males—in fact, females typically mate with more consort partners than do males, to such an extent that they experience a phenomenon known as VAGINAL OVERFLOW because of the amount of sperm they receive from such multiple matings. Rhesus Macaque females also sometimes mount males—such REVERSE mountings can account for 2–6 percent of all heterosexual mountings. Males may become sexually stimulated while a female is mounting them, masturbating or ejaculating spontaneously, and she may also achieve orgasm from rubbing during the mount. Males often masturbate to ejaculation on their own, while females have been observed fondling and sucking their own nipples. Sexual activity with nonoptimal partners also occurs: males occasionally mount their mothers or sisters (incestuous activity accounts for 12–15 percent of all sexual interactions in some populations), and adult-juvenile sexuality (primarily mounting but also fellatio, including with infants) may account for more than 15 percent of all sexual activity. A wide range of interspecies sexual interactions in captivity have also been observed (including a female Rhesus soliciting copulations from a Dog).

Male Rhesus Macaques have a yearly hormonal cycle with a distinct nonbreeding period. Females also commonly experience a postreproductive or “menopausal” stage later in their lives, in which they no longer breed but may still be sexually active. They may also continue to be valued members of the troop, even contributing to the care and raising of infants and juvenile monkeys. In addition, females of all ages participate in a type of “baby-sitting,” in which individuals—in—cluding nonbreeding monkeys—look after infants belonging to other females (and also act as “attendants” during their births). These “aunts,” as they are sometimes called (though they need not be genetically related to the mother), often protect and take care of the infants. Males (who generally do not participate in parenting) also occasionally engage in similar behavior and may even adopt orphaned infants. In some cases, though, “aunts” engage in aggressive or sexual interactions with the infants as well and may even try to “kidnap” another female’s baby. Mothers are also sometimes abusive toward their own infants—shoving, biting, and stepping on the baby’s head have all been observed, and one study showed that about 11 percent of infants are abused in their first two years of life. In addition, heterosexual relations are often characterized by aggression: males frequently attack and may severely wound females that they mate or consort with.

*asterisked references discuss homosexuality/transgender

*Akers, J. S., and C. H. Conaway (1979) “Female Homosexual Behavior in Macaca mulatta.” Archives of Sexual Behavior 8:63–80.

*Altmann, S. A. (1962) “A Field Study of the Sociobiology of Rhesus Monkeys, Macaca mulatta.” Annals of the New York Academy of Sciences 102:338-435.

*Carpenter, C. R. (1942) “Sexual Behavior of Free Ranging Rhesus Monkeys ( Macaca mulatta ) . I. Specimens, Procedures, and Behavioral Characteristics of Estrus. II. Periodicity of Estrus, Homosexual, Autoerotic, and Non-Conformist Behavior.” Journal of Comparative Psychology 33:113–62.

Conaway, C. H., and C. B. Koford (1964) “Estrous Cycles and Mating Behavior in a Free-ranging Band of Rhesus Monkeys.” Journal of Mammalogy 45:577–88.

*Erwin, J., and T. Maple (1976) “Ambisexual Behavior with Male-Male Anal Penetration in Male Rhesus Monkeys.” Archives of Sexual Behavior 5:9–14.

*Fairbanks, L. A., M. T. McGuire, and W. Kerber (1977) “Sex and Aggression During Rhesus Monkey Group Formation.” Aggressive Behavior 3:241–49.

*Gordon, T. P., and I. S. Bernstein (1973) “Seasonal Variation in Sexual Behavior of All-Male Rhesus Troops.” American Journal of Physical Anthropology 38:221–26. *

Hamilton, G. V. (1914) “A Study of Sexual Tendencies in Monkeys and Baboons.” Journal of Animal Behavior 4:295–318.

*Huynen, M. C. (1997) “Homosexual Interactions in Female Rhesus Monkeys, Macaca mulatta.” In M. Taborsky and B. Taborsky, eds., Contributions to the XXV International Ethological Conference , p. 211. Advances in Ethology no. 32. Berlin: Blackwell Wissenschafts-Verlag.

Kaufmann, J. H. (1965) “A Three-Year Study of Mating Behavior in a Free-Ranging Band of Rhesus Monkeys.” Ecology 46:500–12.

*Kempf, E. J. (1917) “The Social and Sexual Behavior of Infrahuman Primates With Some Comparable Facts in Human Behavior.” Psychoanalytic Review 4:127–54.

*Lindburg, D. G. (1971) “The Rhesus Monkey in North India: An Ecological and Behavioral Study.” In L. A. Rosenblum, ed., Primate Behavior: Developments in Field and Laboratory Research , vol. 2, pp. 1–106. New York: Academic Press.

Loy, J. D. (1971) “Estrous Behavior of Free-Ranging Rhesus Monkeys ( Macaca mulatta).” Primates 12:1-31.