Stumptail, and Pig-tailed Macaques being mounted; erection and masturbation by male mountee Rhesus, Pig-tailed, and Crested Black Macaques; thrusting by male Bonobos being mounted; and stimulation of the mountee’s clitoris by her partner’s thrusting in Hanuman Langurs and Japanese Macaques. In addition to direct and indirect genital stimulation during mounting, it is quite likely that male animals being penetrated during anal intercourse also experience stimulation of the prostate gland (which presses against the wall of the rectum). In human males, direct stimulation of the prostate—for instance, during anal intercourse—can be highly arousing and may precipitate or enhance orgasm. A similar capacity is probably present in all male mammals. Although direct evidence (in the form of firsthand accounts) of the pleasurable or arousing nature of this activity is, of course, lacking in nonhuman animals, there is some indirect evidence. A standard technique of inducing erection and ejaculation (for purposes of artificial insemination) in male mammals is through anal and/or prostate stimulation. Known as electroejaculation, this technique involves insertion of an anal probe and stimulation of the rectum—especially in the area of the prostate gland—with a mild electrical current as well as back-and-forth (thrusting) movements of the probe. This technique has proven effective in numerous species of mammals, including virtually all of those in which male homosexual mounting and /or anal penetration occur. For further information on electroejaculation, see Watson, P. F., ed. (1978)
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Hanuman Langur (Srivastava et al. 1991:506–7); for a similar assessment with regard to homosexual activity between males in this species, see Weber and Vogel (1970:77–78). See also Rowell (1967a:23), who states that “sexual” and “dominance” mounts in Savanna (Yellow) Baboons are virtually indistinguishable, and Enomoto (1990:473), who remarks on the difficulty of discriminating between sexual and ritualized dominance mounting in Bonobos because of the gradation between the two. Weinrich (
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Japanese Macaque (Wolfe 1986:268); Rhesus Macaque (Akers and Conaway 1979:78); Greylag Goose (Lorenz 1991:206); Black-winged Stilt (Kitagawa 1989:65, 69) (see also the distinction between same-sex courtship and aggressive/appeasing kantling in Ostriches [Sauer 1972:731; Bertram 1992:15, 50–51]). For species such as these that have a clear distinction between mounts in sexual and nonsexual contexts, only the former are considered (in this book and in most sources) to be homosexual behavior. As noted in chapter 1, some species classified by Dagg (1984) as exhibiting homosexuality (e.g., bush squirrels and degus) are excluded from our roster on the basis of this criterion, because all same-sex mounting in these species appears to fall into this genuinely nonsexual category; see Viljoen, S. (1977) “Behavior of the Bush Squirrel,
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Walrus (Miller 1975:607); Gray Seal (Anderson and Fedak 1985); Oystercatcher (Ens, B. J., and J. D. Goss- Custard [1986] “Piping as a Display of Dominance by Wintering Oystercatchers
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For details of the way that dominance is expressed in these species, see Savanna (Yellow) Baboon (Maxim and Buettner-Janusch 1963:169); Hamadryas Baboon (Stammbach, E. [1978] “On Social Differentiation in Groups of Captive Female Hamadryas Baboons,”
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In some cases, sexual behaviors other than mounting can be correlated with dominance. For example, grooming between males in Nilgiri Langurs and Crested Black Macaques is often performed by a subordinate animal on a more dominant one. Nevertheless, it is apparent that this activity has a clearly sexual component as well: one or both males may become intensely aroused, developing an erection and even ejaculating during the grooming (see Poirier 1970a:334 for Nilgiri Langurs and Poirier 1964:146—47 for Crested Black Macaques). Similarly, adult (dominant) Bonobos often masturbate or massage the genitals of adolescent (subordinate) males, but again, the activity involves clear sexual stimulation (cf. de Waal 1987, 1995, 1997). Also, Squirrel Monkey genital displays are sometimes correlated with dominance, but there are also cases where the association is less than definitive, or where they occur in clearly sexual contexts between animals of the same sex (cf. Talmage-Riggs and Anschel 1973:70; Travis and Holmes 1974:55; Baldwin and Baldwin 1981:295-97; Castell and Heinrich 1971:187-88).
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One cannot help but surmise that it is the heterosexism of many biologists that has led them to focus on mounting behavior to the exclusion of other activities in their appeal to dominance factors—for only in mounting can the positions of the participants be clearly analogized to those of a male and female in a heterosexual interaction. As Fedigan (1982:101 [Japanese Macaque]) points out, underlying the entire discussion of dominance in same-sex interactions is the assumption that homosexual mounting is essentially a transposition from heterosexual copulation—and that males “dominate” females in such interactions. For further evidence against this view, see the discussion of homosexuality as a form of “pseudoheterosexuality” in chapter 4.
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Possible exceptions are same-sex courtship interactions in Mountain Sheep (Geist 1968, 1971), Musk-oxen (Reinhardt 1985), and Cavies (Rood 1972), which have been interpreted as reflecting dominance. Additionally, mounting or other sexual behaviors within a same-sex pair-bond—common in many bird species—does not fit easily into a dominance interpretation, since this usually involves ongoing interaction with only one other animal (rather than the establishment of hierarchical positions within a network of individuals).
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Giraffe (Pratt and Anderson 1985:774—75, 780—81); Crested Black Macaque (Dixson 1977:77-78; Reed et al. 1997:255); Stumptail Macaque (Bernstein 1980:40); Pig-tailed Macaque (Giacoma and Messeri 1992:187); Savanna (Olive) Baboon (Owens 1976:250-51); Squirrel Monkey (Baldwin and Baldwin 1981:295-97; Baldwin 1968:296, 311); Red Squirrel (Ferron 1980:136); Spinifex Hopping Mouse (Happold 1976:147); American Bison (Reinhardt 1985:222-23); Pukeko (Lambert et al. 1994); Sociable Weaver (Collias and Collias 1980:246, 248; in the latter instance, the inconsistency in dominance status was not one of the cases of temporary reversals of dominance that were occasionally seen in this species). In female Squirrel Monkeys, dominance hierarchies are not considered to be a salient feature of social organization in the wild (Baldwin and Baldwin 1981:294-95). However, even when dominance systems appear to develop (e.g., in some captive situations), investigators have found that the rank of females based on their homosexual activities does not agree with other measures of rank (Anschel and Talmage- Riggs 1978:602 [table 1]).
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For some reevaluation and/or critiques of the concept of dominance, see Gartlan, J. S. (1968) “Structure and Function in Primate Society,”
