Monkey business

You don’t have to delve far into the media to recognise what a difficulty  homosexuality presents for the Christian churches and to society in general. It’s no less a problem for biology.

In terms of Darwinian evolution, being gay seems both maladaptive and inefficient, going against the grain of maximising your contribution to the next generation. And if there were a skerrick of a genetic component to homosexuality, natural selection should have removed it from the gene pool long ago. Yet estimates of homosexuality remain steady at about ten per cent. This is thousands of times higher than the most prevalent of deleterious genes. So how does homosexuality persist, and at such high levels?

The answer, according to Stanford University biologist Prof. Joan Roughgarden, is that the Darwinian analysis is flawed. It rests on two assumptions which biologists almost never question—that organisms must be either male or female, and that the sole biological purpose of sex is reproduction. In Evolution’s Rainbow to be published in May and previewed in New Scientist, Roughgarden takes issue with both contentions. She argues that sex, even homosexual sex, can be evolutionarily adaptive in ways other than directly through reproduction—for instance, through the establishment and maintenance of relationships useful to the successful rearing of offspring. In a broad survey of animals, and particularly our close relatives, the apes, she finds hundreds of examples. They may be heterosexual, such as female monkeys in India which are deliberately promiscuous, hiding the identity of the father, thus providing offspring general protection from predatory adult males; or they may be homosexual, such as the female bonobos who form cooperative groups, the members of which gather food collectively.

Whether you agree with Roughgarden’s analysis or not, it is a fascinating example of how personality and culture affect the genesis of (supposedly) objective scientific ideas. Her thoughts would not, perhaps could not, have occurred to Darwin who spent most of his life as an independently wealthy, middle-class, country gentleman in Victorian England. Darwin had trained for the ministry, wrote books on natural history, and lived with a devoted wife who bore ten children—hardly a man to take issue with conventional church teaching and societal wisdom that sex was solely for procreation.

Roughgarden is from a different milieu. A Harvard graduate, she is an established evolutionary biologist and ecologist at one of America’s most respected research institutions. She is also, in her own words, a ‘transgendered woman’, living in the San Francisco area during a time when it has become a centre of gay awareness and pride. The research into the prevalence of homosexuality throughout the animal kingdom, upon which her argument depends, was undertaken in response to that upsurge of self-confidence. No matter how one may view Roughgarden’s theory, her basic arguments are not trivial. They draw attention to the fact that much of our biological theory was formed by people whose viewpoint and knowledge of the biological world was very different from today’s.

Roughgarden’s ideas have already stirred some controversy in gay and feminist academic communities, because some of the conclusions she draws are eminently debatable. The level of debate will only increase leading up to the release of her book. Not for the first time are the teachings of the church going to be challenged by a scientist. 

Tim Thwaites is a freelance science writer.



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