Bruce Bagemihl - Biological Exuberance

120

Northern Elephant Seal (Le Boeuf 1974:173); Red Deer (Darling 1937:170); Black-headed Gull (van Rhijn 1985:87, 100); Common Garter Snake (Mason and Crews 1985:59).

1

Hutchinson, G. E. (1959) “A Speculative Consideration of Certain Possible Forms of Sexual Selection in Man,” American Naturalist 93:81–91.

2

According to sociobiologist James Weinrich, biological “mistakes” such as genetically transmitted diseases occur at very low rates, roughly 1 in 10,000 or less (Weinrich, J. D. [1987] Sexual Landscapes, p. 334 [New York: Charles Scribner’s Sons]). Moreover, such genetic “defects,” rather than being uniformly detrimental, sometimes confer unique abilities on their carriers. People with the genetic “disorder” of William’s syndrome, for example—which occurs in about 1 in 20,000 people—often display extraordinary musical abilities, remarkable verbal skills, and exceptionally empathetic personalities, although they typically also have low IQs and some medical complications (Lenhoff, H. M., P. P. Wang, F. Greenberg, and U. Bellugi [1997] “William’s Syndrome and the Brain,” Scientific American 277[6]:68—73).

3

As in most other “explanations” of homosexuality, these include both “proximate” and “ultimate” factors (a distinction widely employed in evolutionary biology). “Proximate” explanations focus on the immediate behavioral, social, physiological, demographic, environmental, and other factors that supposedly “trigger” or lead to homosexual activity, while “ultimate” explanations focus on the wider reproductive and evolutionary benefits that supposedly accrue from such activity.

4

Weinrich, Sexual Landscapes; Ruse, M. (1982) “Are There Gay Genes? Sociobiology and Homosexuality,” Journal of Homosexuality 6:5—34; Kirsch, J. A. W., and J. E. Rodman (1982) “Selection and Sexuality: The Darwinian View of Homosexuality,” in W. Paul, J. D. Weinrich, J. C. Gonsiorek, and M. E. Hotveldt, eds., Homosexuality: Social, Psychological, and Biological Issues , pp. 183-95 (Beverly Hills, Calif.: SAGE Publications); Wilson, E. O. (1978) On Human Nature , pp. 142-47 (Cambridge, Mass.: Harvard University Press); Trivers, R. L. (1974) “Parent-Offspring Conflict,” pp. 260—62, American Zoologist 14:249-64. For a critique of these theories as applied to humans, see Futuyama, D. J., and S. J. Risch (1984) “Sexual Orientation, Sociobiology, and Evolution,” Journal of Homosexuality 9:157—68. For specific examples of homosexuality cited as a possible population-regulation mechanism—including nonreproductive sexuality as a stress-induced response to overpopulation in some species, and homosexuality as a form of “birth control” in humans—see Calhoun, J. B. (1962) “Population Density and Social Pathology,” Scientific American 206(2):139-48; von Holst, D. (1974) “Social Stress in the Tree-Shrew: Its Causes and Physiological and Ethological Consequences,” in R. D. Martin, G. A. Doyle, and A. C. Walker, eds., Prosimian Biology , pp. 389-411 (Pittsburgh: University of Pittsburgh Press); Denniston 1980:38 (Squirrel Monkey); Harris, M. (1980) Culture, People, and Nature , p. 208 (New York: Harper and Row). For more on the special “role” of homosexual and transgendered humans in some indigenous cultures, see chapter 6.

5

See the discussion of same-sex parenting in chapter 1.

6

See pp. 206–7 for further discussion of these and other alternate parenting arrangements.

7

For a complete list of bird species with helpers, see Brown, J. L. (1987) Helping and Communal Breeding in Birds , pp. 18—24 (table 2.2) (Princeton: Princeton University Press). Three other species in which homosexual behavior occurs (Ostriches, House Sparrows, and Sociable Weavers) are classified by Brown as having helpers, but it is not clear that these represent genuine cases of helping. Even if they did, however, they would still not support the “helper” theory of homosexuality because homosexuality is either not limited to helpers in these species, or else not all helpers engage in homosexual behavior. In Ostriches “helping” behavior actually consists of foster-parenting by breeding pairs of males and females (ibid., p. 161); homosexuality only occurs in males in this species, and probably nonbreeders at that. In House Sparrows helping occurs occasionally among juveniles, probably of both sexes, and in only some populations (p. 31), while homosexual behavior only occurs in (a few) adult males. And in Sociable Weavers, breeding pairs are assisted in building communal nests, probably by birds of both sexes, but such birds do not help feed their young (see Maclean 1973); homosexuality occurs in both breeders and nonbreeders, but only males. Recently, helping behavior by adolescent males has also been discovered in Greater Rheas; however, this phenomenon is distinct from same-sex coparenting (and sexual activity) in this species, which involves adult males‘(Codenotti and Alvarez 1997:570). For other surveys of the phenomena of communal breeding and helpers in birds, see Skutch, A. F. (1987) Helpers at Birds’ Nests: A Worldwide Survey of Cooperative Breeding and Related Behavior (Iowa City: University of Iowa Press); Stacey, P. B., and W. D. Koenig, eds. (1990) Cooperative Breeding in Birds (Cambridge: Cambridge University Press).

8

See chapters 1 and 4 for discussion of the fact that many cases of homosexuality in animals have probably been missed, overlooked, or remain to be discovered.

9

Moynihan (1990:19) states that homosexual pairing and/or mounting is found among nonbreeding Pied Kingfisher males, but does not further specify which categories of nonbreeders known to exist in this species (primary helpers, secondary helpers, or nonhelpers) are involved. However, the likelihood that they are nonhelpers can be deduced from independent descriptions of the behavior of each of these categories. Homosexuality probably does not take place between breeding males and secondary helpers, since the former are antagonistic to the latter, engaging in “intense and prolonged fights” with them (Reyer 1986:288). Likewise for primary and secondary helpers: the former often attack and fight the latter (Reyer 1986:291). Thus, homosexuality probably occurs largely among nonhelping nonbreeders, or among secondary helpers—the latter is less likely, though, since their attentions are usually focused on feeding females, often as potential mates for the next season (Reyer 1984:1170; Reyer 1980:222). Patterns of helping, breeding, and homosexual participation analogous to the bird examples also occur among mammals. In Red Foxes, for example, same-sex mounting occurs both among younger females (nonbreeders and/or helpers) and between them and older breeding females, but only a subset of each; in Bush Dogs, nonbreeders of both sexes act as helpers (Macdonald 1996:535), yet only males occasionally participate in same-sex mounting.

10

In fact, the only possible cases of adoption by homosexual pairs are in Hooded Warblers (where some male pairs may take over nests abandoned by females after they have been parasitized or robbed by predators), Black-headed Gulls (in which adoption of eggs by male pairs has been suggested [van Rhijn and Groothuis 1985:165-66] but not yet documented), and Cheetahs (in which paired males have occasionally been observed temporarily looking after lost cubs [Caro 1994:45, 91]). Coparenting of adopted pups by two females also occurs in Northern Elephant Seals, Gray Seals, and Spotted Seals, although the two females do not appear to have a “pair-bonded” or sexual relationship with each other.