Biological Exuberance: Animal Homosexuality and Natural Diversity

In some cases, conflicting verbal assessments of the prevalence of homosexual activity are offered by the same investigators, when the actual quantitative data show a relatively high occurrence. Homosexual courtship/copulation in Pukeko, for example, is described as being both “common” and “relatively rare”—the actual rate of 7 percent of all sexual activity is in fact fairly high compared to other species (and the same-sex courtship rates are even higher). Likewise, a report on Black-headed Gulls states, “Homosexual pairs were also rare,” then a few pages later counterasserts that “male-male bonds occurred rather commonly”—and at approximately 16 percent of all pairs observed, the actual rates support the latter interpretation more than the former.⁵⁶ Not only are these assessments inconsistent and unfair with regard to the observed rates of homosexuality, they also run counter to a standard cross-species measure of heterosexual frequency. Although there is no absolute or universal criterion for what is “rare” or “common,” biologists do recognize a “threshold” of 5 percent as being significant where at least one heterosexual behavior is concerned—polygamy. When this mating system is exhibited by only a minority of the population (as is true in many birds, for example), it is nevertheless considered to be a “regular” feature of the species’ behavioral repertoire when its incidence reaches 5 percent. This is certainly far less than the rate of homosexuality in many species where same-sex behavior is regarded as “uncommon” or “exceptional.”⁵⁷

In a vivid example of the marginalization that often surrounds discussion of animal homosexuality, scientists sometimes find their own descriptions of same-sex activity published with “amendments,” “asides,” or “explanations” inserted by journal or reprint editors who are uncomfortable with the content or appellation. For example, one ornithologist’s description of homosexual activity in House Sparrows and Brown-headed Cowbirds was embellished with a note from the editor of the journal where it appeared, offering several implausible “reinterpretations” of the behavior that eliminated any sexual motivation. Likewise, when descriptions of homosexual activity in Baboons from the 1920s were reprinted nearly half a century later, a scientist who penned the introduction to the new edition felt compelled to annotate the offending passages with the “modern” viewpoint that such activity is not really homosexual. And editors of the journal British Birds scrambled to try to “explain” a case of homosexual pairing in male Kestrels as actually involving a “male-plumaged female” (i.e., a female bird that looked exactly like a male). They added in their published postscript to the article that this putative plumage variation was, in their opinion, “of much more interest than the copulation or attempted one between the two males” that was the primary focus of the author’s report.⁵⁸

In a similar vein, one scientist who observed a pair of female Chaffinches hedged his bets by saying only that “female-plumaged” birds were involved, leaving open the possibility that one might still have been a male (and consequently part of a heterosexual pair)—even though there was absolutely no evidence that either bird could have been a male. He finally had to concede that the birds “were surely females.” Sometimes this strategy backfires, as in the case of an early description of courtship display in Regent Bowerbirds (mentioned previously), in which the presumed “female-plumaged” birds both turned out to be males—and therefore still participants in homosexual activities.⁵⁹ These cases show that scientists are sometimes reluctant even to commit to the sex of the animals they are observing if it seems that homosexuality might be involved—in stark contrast to the haste with which they usually judge (or assume) participants to be opposite-sexed on the scantiest of evidence.

The Love That Dare Not Bark Its Name

Although the first reports of homosexual behavior among primates were published >75 years ago, virtually every major introductory text in primatology fails to even mention its existence.

—primatologist PAUL L. VASEY, 1995⁶⁰