Biological Exuberance: Animal Homosexuality and Natural Diversity

Combining these three behavioral categories yields a figure of just over 20 percent: roughly one-fifth of all interactions, on average, are homosexual in mammal and bird species that have at least some form of same-sex courtship, sexual, and/or pair-bonding activities. If one figure could be said to represent the overall frequency of homosexual activity in animals, this would probably be the one—but it is virtually impossible to come up with a truly “representative” number. A figure such as this collapses a multiplicity of behaviors (both between and within species), it represents only a fraction of the animals in which homosexuality has been documented, it glosses over many observational and theoretical uncertainties (not the least of which is widely differing sample sizes), and it misleadingly equates often radically unlike phenomena (different forms of heterosexual and homosexual behaviors, disparate social contexts, and so on). A less satisfying, but ultimately more meaningful, “formula” for understanding frequency is to recognize that there is no one overall frequency, no single formula. As in all aspects of animal homosexuality, different species exhibit an extraordinary range of rates, quantities, periodicities, and proportions of same-sex behavior—a diversity that is equal to the variation in the behaviors themselves. We can make tallies for particular species, develop formulas for certain populations or behaviors, and calculate percentages, time budgets, and so on—thereby trying to gain some overall impressions regarding the prevalence of homosexuality in animals. In the end, though, we must acknowledge that our measures are at best imperfect—and what we are attempting to quantify is, in many senses, incalculable.

Within Genders, Without Genders, Across Genders

The traditional view of the animal kingdom—what one might call the Noah’s ark view—is that biology revolves around two sexes, male and female, with one of each to a pair. The range of genders and sexualities actually found in the animal world, however, is considerably richer than this. Animals with females that become males, animals with no males at all, animals that are both male and female simultaneously, animals where males resemble females, animals where females court other females and males court other males—Noah’s ark was never quite like this! Homosexuality represents but one of a wide variety of alternative sexualities and genders. Many people are familiar with transvestism or transsexuality only in humans, yet similar phenomena are also found in the animal kingdom. Although this book focuses primarily on homosexuality, it is helpful to compare this with related phenomena that are often confused with homosexuality, and to discuss some specific examples of each.

Many animals live without two distinct genders, or with multiple genders. In hermaphrodite species, for instance, all individuals are both male and female simultaneously, and hence there are not really two separate sexes; in parthenogenetic species, all individuals are female and they reproduce by virgin birth. A number of other phenomena in the animal kingdom—for which we will use the cover term transgender—involve the crossing or traversing of existing gender categories: for example, transvestism (imitating the opposite sex, either behaviorally, visually, or chemically), transsexuality (physically becoming the opposite sex), and intersexuality (combining physical characteristics of both sexes).⁴⁶