Biological Exuberance: Animal Homosexuality and Natural Diversity

and typically male activities such as defense of the goslings.³¹

A multiplicity of gender-role mixtures that defy categorization into any of these three types is the norm in species like the Black-headed Gull. Detailed comparisons of both heterosexual and homosexual pairs showed that birds in same-sex pairs exhibit neither stereotypically “male” nor “female” behaviors. Rather, the frequency with which they perform various courtship and pair-bonding activities tends to be distinct from, or intermediate between, that of both males and females in opposite-sex pairs. For example, the maximum rate of “ceremonial encounters” (a type of courtship interaction) in homosexual pairs exceeds that of both partners in heterosexual pairs. On the other hand, rates of “long-calling” and “head-flagging” (other forms of courtship) tend to be intermediate between those of heterosexual males and females, while the rate of courtship “begging” by males in homosexual couples is generally as low as that of males in heterosexual pairs (which itself is generally lower than that of heterosexual females).³² In addition, both males in homosexual pairs usually build the nest (which is a typically “male” activity in heterosexual couples), although there is also variation between individuals in this regard, with only one partner contributing to the nest in some male pairs.

The “pseudoheterosexual” interpretation of animal behavior offers striking parallels to stereotypical views about human homosexuality. Scientific puzzlement over assigning animals “male” or “female” roles echoes the refrain often heard by gay and lesbian people, who are frequently asked, “Which one plays the man (or woman)?” The assumption is that homosexual relationships must be modeled after heterosexual ones—a view that is as narrow a conception of human relationships as it is of animal sexuality. Each partner in a gay or lesbian relationship (or sexual encounter) is thought to “play” one-half of a heterosexual couple. In reality, far more complex and multidimensional expressions of gender categories are involved, even (or perhaps especially) when the partners appear most “heterosexual” to outside observers. Some people do not structure their homosexual interactions along gendered lines at all; others do, but re-create typically “male” and “female” patterns in new configurations. To give just one example: butch-femme lesbian relationships have long been viewed as simplistic imitations of heterosexuality, in which the butch partner is the “man” and the femme partner is the “woman.” Lesbians whose erotic lives are organized along these lines, however, describe eloquently how their actual experiences are far different from this. Neither partner is “copying” heterosexual roles; rather, each is taking elements of masculinity and femininity and alloying them in different combinations and intensities to create female-specific genders. As one lesbian has said about the kind of women she is attracted to, a masculine lesbian is not an imitation man, but a real butch.³³ If even this most superficially “heterosexual” gender presentation is more than what it appears, imagine the possibilities when homosexual interactions are gender-role-defined in other ways, or not at all. Such “possibilities” are in fact everyday realities in the lives of both humans and animals.

Over the past thirty years, a sophisticated analysis of gender categories has been emerging from within the feminist, gay and lesbian, and transgender movements, one that challenges basic notions such as “male” and “female,” “masculine” and “feminine,” “mannish” and “effeminate.” These movements are also calling for a recombining and reimagining of categories such as these, rather than simply their denigration or abolishment. Unfortunately, zoologists for the most part are still operating under an earlier, outmoded conception of gender roles (both heterosexual and homosexual)—one that is inconsistent with the actualities of sexual and gender expression within the animal and human worlds. If any progress is to be made in the study and understanding of animal homosexuality and transgender, scientists and nonscientists alike will need to acquire the sort of multifaceted view of gender and sexuality that is now being articulated within these human liberation movements.

“The Lengths to Which Deprived Creatures Will Go”—Homosexuality as Substitute Heterosexuality

One of the most prevalent myths about animal homosexuality is that it is invariably caused by a shortage of members of the opposite sex. This is typically attributed to skewed sex ratios in the population (more males than females, or vice versa), or the unavailability of opposite-sex partners due to sex segregation, hostility or indifference on the part of potential mates, or other factors. This belief is widespread among nonscientists and is also the most common “explanation” that biologists have proposed for the occurrence of homosexual behavior in animals. In more than 65 species of mammals and birds, for example, same-sex activity is claimed by zoologists to result from individuals being “unable” to mate heterosexually. Sometimes this is attributed to a predominance of one sex over the other in wild or captive populations: the formation of lesbian pairs in Australian Shelducks and Ring-billed Gulls, for instance, is supposedly “caused” by an excess number of females (65 percent females in Shelduck populations, 55 percent females in Ring-billed Gulls).

Homosexual pairs in Mute Swans occurring in populations with unbalanced sex ratios are said to be “examples of the lengths to which deprived creatures will go to satisfy their natural urge to reproduce.” In some cases, homosexual behavior is labeled a “substitute” for heterosexuality or “redirected” heterosexual behavior, resulting from a variety of factors. For example, it is claimed that individuals are “prevented” from mating with (or otherwise having access to) the opposite sex by other (often higher-ranking) animals, or by the overall social organization (e.g., in Mountain Sheep, Bottlenose Dolphins, or Killer Whales). Alternatively, it has been suggested that individuals resort to homosexuality when their heterosexual advances are met with refusal or disinterest (e.g., in White-handed Gibbons, West Indian Manatees, Asiatic Elephants). In a few cases (e.g., Hanuman Langurs, Lions, Sage Grouse) scientists have even suggested that females turn to one another because they have not been “satisfied” or received enough attention from male partners—a version of the widespread stereotype about the “cause” of lesbianism among people.³⁴

The line of reasoning in “explanations” such as these is curious, since it implies that unless there is an adequate supply of the opposite sex, homosexuality will inevitably ensue. This is actually an unintentional assertion of the relative strength of the homosexual urge, or correspondingly, the relative weakness of the heterosexual imperative—for the stronghold of heterosexuality must be tenuous indeed if such factors are capable of upsetting the balance. Besides this, however, unavailability of the opposite sex—what we will call the shortage hypothesis—is simply incompatible with the facts.

Surplus Homosexuality

The shortage hypothesis cannot be a universal explanation for animal homosexuality because of the many examples of animals engaging in same-sex activity when opposite-sex partners are freely available.³⁵ In Orang-utans, Japanese Macaques, Stumptail Macaques, Rhesus Macaques, Common Gulls, Black-headed Gulls, King Penguins, Galahs, and more than 40 other species, scientists have documented individuals either ignoring opposite-sex partners and seeking out same-sex partners instead, or else engaging in homosexual activity more or less concurrently with heterosexual activity (i.e., even when opposite-sex partners are accessible, as already mentioned in the discussion of simultaneous bisexuality).³⁶ In fact, in a surprisingly large number of species, homosexual activity is positively correlated with heterosexual activity: same-sex interactions actually increase as animals gain access to opposite-sex partners and decrease in their absence. This is the exact reverse of what would be expected if homosexuality resulted from a lack of access to heterosexual mating opportunities.

Homosexual activity among male Bottlenose Dolphins in captivity, for instance, actually declined when females were removed from their tank, while aggressive interactions between the males increased. Conversely, female Squirrel Monkeys in one study engaged in virtually no homosexual activity when kept in same-sex groups, yet showed significant rates of homosexual mounting and other activities (along with heterosexual behaviors) when males were introduced into their group. Another study of this species found that females with the most attention from heterosexual partners also engaged in the most homosexual pursuits. In Bonobos, Stumptail Macaques, Savanna (Yellow) Baboons, and West Indian Manatees, same-sex activity is often stimulated by opposite-sex activity (and vice versa), with the result that sessions may involve both heterosexual and homosexual encounters among multiple participants. Homosexual mounting in Pukeko is most prevalent in breeding groups that have the greatest amount of heterosexual activity, while homosexual mounts in Common Murres become more common as promiscuous heterosexual mounts also increase in frequency (although the latter may, ironically, result from a decrease in available females). In some species, individuals that participate in the most heterosexual matings may also engage in the most homosexual ones, as in Sociable Weavers and Bonnet Macaques. Conversely, animals that are the least active heterosexually are often the least active homosexually. In Ruffs, for example, the class of males who do not generally mate with females (known as marginal males) also rarely participate in homosexual matings, while in one study of Japanese Macaques, the only female who did not consort with any other females also failed to