Biological Exuberance: Animal Homosexuality and Natural Diversity

Conversely, researchers have found hormonal differences between individuals in some species that exhibit homosexual behavior, but not in animals that participate specifically in same-sex activity. Endocrinological studies of Pied Kingfishers, for example, reveal that some males have lowered testosterone levels (as well as smaller gonads), but these individuals constitute one class of nonbreeding “helpers” who assist their parents in raising young. Few, if any, such males are involved in the homosexual pair-bonding or mounting activity that sometimes occurs in this species. Likewise, a certain category of nonbreeding Orang-utans (those with “flanges”) often have elevated estrogen levels—but homosexual activity is neither characteristic of, nor exclusive to, such individuals. In other species scientists have determined that an “unusual” hormonal profile is found in the majority of individuals, but this is not linked to homosexual activity. In Spotted Hyenas, females generally have higher levels of a particular “male” hormone (a type of androgen) than do males, yet only a fraction of them actually participate in same-sex mounting; moreover, pregnant females also have elevated levels of testosterone (regardless of the sex of their fetus) but are not more prone to same-sex mounting. Likewise, all female Western Gulls have high levels of androgens (including testosterone)—nearly equal to those of males—regardless of whether they are in homosexual or heterosexual pairs.¹¹³ These examples illustrate another important point: in many species a portion of the population routinely exhibits hormonal profiles (or other physiological characteristics) that differ from the “norm”—sometimes correlated with nonbreeding—yet only when individuals display overt homosexuality or transgender is the label of abnormality or dysfunction applied.

In most instances where a physiological “explanation” is advocated, this is purely conjectural, not based on any actual hormonal studies of the animals involved, and often highly improbable on independent grounds. For example, the connection between male fetal hormones and a pregnant mother’s behavior—advocated as an “explanation” for mounting among female Takhi—is entirely speculative, since endocrinological profiles were not drawn up for the specific individuals involved in same-sex activity. Moreover, even if there were a connection, it would be at most only a partial explanation for this (and other) species. One Takhi mare mounted males when carrying a male fetus rather than mounting other females and also failed to show similar behavior the next year when she was again pregnant with a male fetus.¹¹⁴ Thus, additional factors must be involved in determining whether such mares participate in homosexual, bisexual, and/or heterosexual (reverse) mounting behavior, if any of these. More generally, this explanation does not have wide applicability to other species. For example, only a fraction of Domestic Horses (which are closely related to Takhi) ever show mounting behavior of any sort when pregnant.¹¹⁵ In addition, homosexual behavior by pregnant females occurs in less than 8 percent of all mammals in which female homosexual mounting has been documented, and in none of these species is the behavior exclusive to pregnant females (or to pregnant females carrying male fetuses). A fetal hormonal “explanation” is irrelevant, as well, for huge segments of homosexual activity, such as same-sex behaviors in animals that do not get pregnant (males of virtually all species and females of egg-laying species, for example).

In addition to being empirically unfounded, physiological explanations are also suspect on conceptual grounds. Almost without exception, hormonal or other pathological accounts of homosexuality focus on the animal exhibiting “gender-atypical” behavior, e.g., the male being mounted or the female doing the mounting. The partners of these individuals are usually considered to be physically “normal” animals whose behavior warrants no further consideration. Yet in many cases the “gender-conforming” partners are equally active participants in homosexual activity, sometimes even initiating same--sex interactions. As we saw in the discussion of “pseudoheterosexual” explanations, this categorization of animals into gender-conforming versus nonconforming, or “truly homosexual” versus “not-quite-homosexual” individuals, is in most cases arbitrary. It reflects not so much any inherent qualities or meaningful behavioral attributes in the animals themselves, but rather the observer’s biases or conceptual categories.¹¹⁶