Biological Exuberance: Animal Homosexuality and Natural Diversity

interpretation, heterosexual “competence” is apparently so elusive (or difficult to achieve and maintain) that it requires constant, albeit indirect, reinforcement through the help of homosexuality. When we examine the realities of animal behavior we find that in many cases heterosexual mating is far from the automatic or “natural” occurrence that it is commonly assumed to be, and it does require some “practice” (see the next section). However, this “explanation” does a disservice to both heterosexuality and homosexuality in its view of the former as unnecessarily tenuous and the later as necessarily derivative.

Even in species where homosexuality is limited to younger animals or to adult-juvenile interactions, there are often serious discontinuities in participation that challenge a practice interpretation. For example, in the Guianan Cock-of the-Rock, homosexual courtship and mating occur between adolescent and adult males and have been classified as “practice” behavior on the part of the younger males. However, there is a curious gap in the age distribution of participating males: primarily one-year-olds are involved, while two-year-olds almost never participate in such activity. Could it be that once they pass the yearling stage, they no longer need any “practice”? Most definitely not: scientists studying this species report that when males first acquire their own territories, between the ages of three and five, they continue to practice their courtship—but largely without homosexual interactions—thereby gaining valuable experience that they will need before embarking on heterosexual mating.⁴⁷ Why should birds first “practice” using homosexuality as one-year-olds, then cease such practice as two-year-olds, only to resume practice without homosexuality as three-to-five-year-olds, and then once again participate in homosexual “practice” sessions with younger males when they become older? And what exactly is the role of the adult males who willingly participate in all of these “practice” sessions? It seems unlikely that they need to “improve” their skills, too, or that they are simply serving as “mentors” to (probably unrelated) males, altruistically providing them with the opportunity to rehearse their mating skills. Although younger males may gain sexual and courtship experience as an indirect result of homosexual interactions, this appears to be a relatively minor by-product of such activity and is highly problematic as an overall “explanation” for the behavior.⁴⁸

There are other questionable aspects to the notion that homosexual behavior is merely rehearsal for heterosexual behavior. In many species where a “practice” interpretation has been suggested, only a small fraction of the population ever engages in same-sex activity, and often an individual participates only a handful of times. It seems highly unlikely that much sexual experience, or any useful “training,” could be gained from such activity.⁴⁹ Moreover, in many species young animals practice heterosexual behavior by participating directly in heterosexuality, either with adults or with each other. In other animals— including ones in which adults engage in homosexuality—heterosexual practice is accomplished without partners or overt same-sex activity. For example, adolescent male Sage Grouse learn the complex courtship display of their species by imitating older males, practicing the “strutting” movements and sounds while they are gathered in their own groups on the periphery of the breeding grounds. Occasionally an older male joins the group so that he can—in the words of one ornithologist—“demonstrate the fine points of strutting to the rapidly maturing novices,” but no homosexual courtship or copulation takes place, and in fact homosexual activity in this species is limited to adult females. Among Montagu’s harriers and several other species of raptors, young birds are trained in heterosexual courtship displays by parents of both sexes without any homosexual activity.⁵⁰ Even if homosexual behavior were training for heterosexuality, this raises more questions than it answers. Why must some animals “resort” to same-sex practice while others can use opposite-sex interactions (or solo practice)? Why does homosexual “training” in some species involve adults “helping” younger animals, while in other species juveniles only “practice” amongst themselves? And why do some individuals apparently not need to “practice” at all? It is clear from these examples that a “practice” interpretation of homosexuality is at best of limited applicability and explanatory value.⁵¹

Finally, there is a curious gender bias in the application of a “practice” interpretation to homosexuality—in the overwhelming majority of cases, only male animals are said to require such rehearsal.⁵² Where complicated courtship displays are performed only by the male of the species, this is perhaps understandable, but why should it be that no female needs to “practice” sexual activity by engaging in same-sex activity? In many animals, especially primates, females are active participants in heterosexual intercourse, often initiating sexual activity and adopting specific postures, positions, or movements as part of a sexual interaction. In most bird species, heterosexual copulation is impossible without the cooperation and active participation of the female: since most male birds do not have a penis, mating can usually only occur if the female actively facilitates the interaction, for example by positioning herself in such a way as to allow genital contact. Yet in none of these species has it been suggested that females “practice” heterosexual mating via homosexual copulation—not because practice isn’t required, or because lesbian activity could not serve this “function,” but because many scientists still regard the female as an essentially passive participant in sexual activity.⁵³ This is highly revealing—not only of sexist attitudes in biology, but also of the true “utility” of this explanation. It is not applied systematically and carefully to all potentially relevant cases: more often than not, it is simply introduced when most other “explanations” have failed, a convenient tool with which to discount or dismiss homosexual activity.

Homosexuality as a Breeding Strategy

Some nonsexual interpretations of homosexual activity discussed in the previous chapters hinge on the indirect contribution of homosexuality to heterosexuality. For example, it has been suggested that homosexuality reinforces group cohesion and social bonds between individuals, thereby improving their well-being and allowing them, ultimately, to reproduce more successfully. It has also been claimed that homosexual “alliances” between animals improve their chances of gaining heterosexual copulations.⁵⁴ Some scientists have been even bolder in their view of the connection between homosexual and heterosexual activity, regarding the two to be directly related or even essentially continuous: same-sex activity is seen as simply an alternative breeding strategy adopted by some animals, or a way to attract or acquire partners of the opposite sex.⁵⁵ It has been proposed, for example, that female Rhesus Macaques sometimes form homosexual consortships to gain access to a male who is himself consorting with their female partner, or that male Bottlenose Dolphins form pairs with each other to seek out female partners.⁵⁶

Another standard “explanation” for homosexual activity among females, especially mammals, is that it attracts males and stimulates them to mate heterosexually. It has also been suggested that female mammals mount each other primarily when one or both partners are in heat, and hence homosexual activity acts as a signal to males of when females are ready to mate. A variation on the notion of homosexuality as a stimulant for heterosexuality is the speculation that males stimulate their own libidos by engaging in same-sex activity (rather than attracting female partners). For example, erotic fighting in African Elephants (during which both participants become sexually aroused) is claimed to stimulate the males so that they can then go out and seek female partners, while male homosexuality in Greenshanks and Golden Plovers is claimed to stimulate and strengthen the birds’ heterosexual drive.⁵⁷

Most of these rather fanciful speculations are not based on any systematic evidence, and in fact there are many arguments against such interpretations. To begin with, homosexual activity in many species is not restricted to the breeding season (i.e., the time when it could “stimulate” heterosexual mating) or to females who are in heat. In more than a third of the mammals and birds for which information is available concerning the chronology of homosexual activity, it occurs either year-round (i.e., both in the breeding and nonbreeding seasons or in females regardless of whether they are in heat or fertile), or else only during the nonbreeding season.⁵⁸ In some cases, the majority of homosexual activity occurs when females cannot conceive, e.g., when they are pregnant (some populations of Japanese Macaques) or during nonfertilizable stages of their cycle (Hanuman Langurs),⁵⁹ and therefore it cannot contribute to heterosexual mating.

Furthermore, even when homosexual activity does take place during the breeding season or at times when females can conceive, cases where it attracts members of the opposite sex or stimulates heterosexual mating activity are the exception, not the rule. In most species, other animals are entirely disinterested, nonchalant, or “underwhelmed” by any same-sex activity they may happen to observe (as discussed in chapter 2). Members of the opposite sex are often entirely absent from the vicinity (Hanuman Langurs) or may even stay away or leave when homosexual activity is taking place (Guianan Cock-of-the-Rock) or be chased away or ignored when they attempt to interact with animals engaging in homosexual activity (Japanese Macaques, Hanuman Langurs). Moreover, in many species homosexual alliances do not actually “improve” their participants’ chances at gaining opposite-sex partners,