Do Animals Exhibit Homosexuality?
March 2012| Yale Scientific 14
Recent research has found that homosexual behavior in animals may be much more common than previously thought. Although Darwin’s theory of natural selection predicts an evolutionary disadvantage for animals that fail to pass along their traits through reproduction with the opposite sex, the validity of this part of his theory has been questioned with the discoveries of homosexual behavior in more than 10% of prevailing species throughout the world.
Currently, homosexual behavior has been documented in over 450 different animal species worldwide. For instance, observations indicate that Humboldt, King, Gentoo, and Adélie penguins of the same sex engage in “mating rituals like entwining their necks and vocalizing to one another.” In addition, male giraffes have also been observed engaging in homosexual behavior by rubbing their necks against each others’ bodies while ignoring the females. Yet another example is lizards of the genus Teiidae, which can copulate with both male and female mates.
Biologists Nathan W. Bailey and Marlene Zuk from the University of California, Riverside have investigated the evolutionary consequences and implications of same-sex behavior, and their findings demonstrate benefits to what seems to be an evolutionary paradox. For example, their studies of the Laysan albatross show that female-female pairing can increase fitness by taking advantage of the excess of females and shortage of males in the population and provide superior care for offspring. Moreover, same-sex pairing in many species actually alleviates the likelihood of divorce and curtails the pressure on the opposite sex by allowing members to exhibit more flexibility to form partnerships, which in turn strengthens social bonds and reduces competition. Thus, not only do animals exhibit homosexuality, but the existence of this behavior is quite prevalent and may also confer certain evolutionary advantages. (source)
To Western science, homosexuality (both animal and human) is an anomaly, an unexpected behavior that above all requires some sort of “explanation” or “cause” or “rationale.” In contrast, to many indigenous cultures around the world, homosexuality and transgender are a routine and expected occurrence in both the human and animal worlds…[ Bruce Bagemihl, Biological Exuberance: Animal Homosexuality and Natural Diversity(New York: St. Martin’s Press, 1999) 215].
Bonobos, which have a matriarchal society, unusual among apes, are a fully bisexual species—both males and females engage in heterosexual and homosexual behavior, being noted for female-female homosexuality in particular. Roughly 60% of all bonobo sexual activity occurs between two or more females. While the homosexual bonding system in Bonobos represents the highest frequency of homosexuality known in any species, homosexuality has been reported for all great apes (a group which includes humans), as well as a number of other primate species.
Dutch primatologist Frans de Waal on observing and filming bonobos noted that there were two reasons to believe sexual activity is the bonobo’s answer to avoiding conflict. Anything that arouses the interest of more than one bonobo at a time, not just food, tends to result in sexual contact. If two bonobos approach a cardboard box thrown into their enclosure, they will briefly mount each other before playing with the box. Such situations lead to squabbles in most other species. But bonobos are quite tolerant, perhaps because they use sex to divert attention and to defuse tension.
Bonobo sex often occurs in aggressive contexts totally unrelated to food. A jealous male might chase another away from a female, after which the two males reunite and engage in scrotal rubbing. Or after a female hits a juvenile, the latter’s mother may lunge at the aggressor, an action that is immediately followed by genital rubbing between the two adults. (source)
- Joan Roughgarden, Evolutions rainbow: Diversity, gender and sexuality in nature and people, University of California Press, Berkeley, 2004; pp.13-183
- Vasey, Paul L. (1995), Homosexual behaviour in primates: A review of evidence and theory, International Journal of Primatology 16: p 173-204
- Sommer, Volker & Paul L. Vasey (2006), Homosexual Behaviour in Animals, An Evolutionary Perspective. Cambridge University Press, Cambridge.
- Douglas, Kate (December 7, 2009). “Homosexual selection: The power of same-sex liaisons”. New Scientist. Retrieved 2009-12-21.