Homosexuality, Animals, Evolution and Morality

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Why would same-sex behavior evolve at all when it runs counter to evolutionary principles? But does it? In fact there are many good reasons for same-sex sexual behavior. Evolutionary biologists Marlene Zuk and Nathan Bailey from the University of California, Riverside suggest that in a species where it is common, it is an important driving force in evolution.

Same-sex behavior is not necessarily synonymous with same-sex preferences, which have been observed in only a handful of animals. Neither can you necessarily infer anything about sexual orientation from same-sex behavior. Orientation is tricky to establish because it requires information about the consistency of partner preferences over a long period of time. Nevertheless, even narrowing the scope to sexual behaviors rather than preferences or orientation leaves a huge evolutionary puzzle. Why would individuals expend time and energy in activities that fail to increase reproductive success? Could the sheer numbers engaging in same-sex behavior mean that it has survival benefits after all?

First, there are the adaptive hypotheses, which provide an explanation for same-sex behavior that would boost the biological fitness of one or more of the individuals involved. For example, several species, including bottlenose dolphins, seem to use same-sex behaviors to promote social bonding. Others may have evolved them as a form of intrasexual conflict. Indirect insemination provides a third possible adaptive advantage, as in the flour beetle where mounting males transfer sperm onto the other males, who then inadvertently inseminate a female with it later on. Then there is the practice hypothesis, that individuals are honing their skills for mating, which seems to hold good for male fruit flies at least.

Several other adaptive sociobiological explanations have been invoked to explain same-sex behavior in humans, including kin selection or inclusive fitness whereby homosexuals reproduce not directly, but indirectly, through aid given to relatives. So rather than expend energy on direct reproduction, homosexuals channel resources toward their kin, giving their families a special advantage; helping to further the genes they share with close family members.

There are also various non-adaptive explanations. Mistaken identity could indeed be one cause. Van Gossum’s damselflies exemplify another idea, known as the prisoner effect, in which depriving individuals of interaction with the opposite sex prompts them to mate with members of their own sex. Then there is the evolutionary by-product hypothesis – selection for some other independent trait, such as high sexual responsiveness, might make individuals more likely to participate in same-sex sexual behavior. It has also been suggested that same-sex behaviors appear when organisms are imperfectly adapted to their environment.

Even without further investigation of these hypotheses there is enough evidence to conclude that same-sex sexual behavior has a wide variety of origins. However, it remains very important to realize that homosexuality in nature is no guide to morality. Fallacious arguments remain fallacious even when used in support of a worthy cause. When the documentary film March of the Penguins came out in 2005, some religious groups tried to exploit it to promote a conservative social agenda. To them, the penguins’ apparent monogamy and selfless parenting affirmed the rightness of traditional family values.

This is a logical error sometimes called the “naturalistic fallacy”: you cannot draw inferences about what is right from what happens in nature. Penguin behavior tells you nothing about human morality. The same applies to same-sex sexual behavior in animals. It might be tempting to use animal examples to refute claims that homosexuality is unnatural and therefore wrong. That would be a mistake. We have no need for fallacious arguments to support basic human rights.

Tags: animals, evolution, homosexuality, morality, same-sex behavior