Toronto Globe and Mail

Why not a third sex? And a fourth, and . . .

By MICHAEL RUSE

UPDATED AT 4:20 PM EDT Saturday, Jul 10, 2004

Evolution's Rainbow: Diversity, Gender, and Sexuality in Nature and People By Joan Roughgarden University of California Press, 474 pages, $43.50

The chief mechanism of evolutionary change, propounded by Charles Darwin in 1859 in his Origin of Species, is natural selection. More organisms are born than can possibly survive and reproduce. There must be a struggle for existence and consequent differential reproduction: Some organisms have offspring and others do not. Success in this process is a function of the characteristics possessed by (and only by) the winners, the fit. This leads to ongoing change and moreover to the evolution of adaptations, things like hands and eyes that help in the struggle.

No one has ever suggested that natural selection is the only mechanism. Darwin himself posited a subsidiary mechanism, sexual selection. This is supposed to take place between members of the same species, and centres on the struggle for mates. Darwin thought that there are two varieties: male combat, leading to such things as the antlers of deer, and female choice, leading to such things as the tail feathers of the peacock.

Sexual selection has had a troubled history. The co-discoverer of natural selection, Alfred Russel Wallace, rejected the notion of female choice. He thought, as many have since, that it is altogether too anthropomorphic. Who is to say that peahens have the same sense of beauty as humans? But far from dismissing or modifying sexual selection, Darwin became increasingly enamoured of the notion, and in his book on our own species -- The Descent of Man -- made much of sexual selection as a cause of human evolution. In particular, he thought it responsible not only for our specific human features (like hairlessness and large brains), but for the major differences between races.

After Darwin, however, the idea lay dormant for many years. Generally, inasmuch as it was discussed at all, it was rolled into natural selection as a minor variant. But in the past three or four decades, with increased interest in animal and human behaviour (so-called "sociobiology"), sexual selection has again found favour. Today, it is considered a major factor in the evolutionary process, for animals and humans.

Joan Roughgarden does not like sexual selection, and her book Evolution's Rainbow: Diversity, Gender, and Sexuality in Nature and People, is a polemic against the idea. Normally, one would not start discussing a person's thesis by talking about the person herself, but in this case it is both legitimate and necessary. As Jonathan Roughgarden, the author had a very distinguished career as an evolutionary ecologist. Then, a few years ago, he made the crossing over the sexual divide. Although Joan Roughgarden denies that this book is a cryptic autobiography -- indeed, one learns that she refused one publisher precisely because this is what they wanted -- it is infused with that history, and moreover has been promoted with much fanfare precisely because the author is writing from a personal standpoint.

In particular, in the body of the work, Roughgarden makes much of her transgendered status. She stresses that her dislike of sexual selection stems not just from the fact that she thinks the notion false, but also that it is morally pernicious because it belittles the status of people like herself. This is not to say that we should judge the content of her book purely in terms of origins, but it is to say that if we find the work to be curiously lopsided -- and I think it is -- then it might just be the case that what we have here is less disinterested scholarship and more special pleading.

Essentially, Roughgarden's objection to sexual selection is that it posits that there are just two sexes, and moreover makes the (hetero)sexual reproduction of these sexes absolutely central to the evolutionary process. She argues that, in the animal and human worlds both, this is false. So false, that sexual selection cannot and should not be redeemed. The human world has a huge number of people like herself who do not fit into the neat male/female dichotomy, and sexual selection ignores or downgrades them.

The same is true also of the animal world. Homosexuality is almost the norm in many species, and thereby blasts a hole right through assumptions about sex and competition for mates. Although Roughgarden frequently warns against assuming that what is true of animals is thereby natural and hence good for humans, she knows the conclusion to be drawn. Darwin was morally biased and scientifically wrong. Time to move on. Time to move on, in fact, to Roughgarden's own theory, which suggests that animals of the same sex universally and naturally copulate together, to forge bonds in facing life's battles.

This sort of stuff goes down well on university campuses, especially in areas like cultural studies that are big into the oppression of the minority by the majority -- the hegemony of heterosexism and all of that sort of thing. But, undoubtedly thereby showing that I am part of the problem, let me say that this all strikes me as complete hogwash. A scientist as brilliant as Roughgarden can only be saying these silly things because she has such a strong, extra-scientific agenda. In fact, her science is as barmy as her theology, as when later in her book she argues that, although St. Paul explicitly condemned men lying with men and women with women, he was not at all against homosexuality. He was a real gay-pride type, apparently, whose true concern was sexually transmitted diseases.

Roughgarden is eager to show that having two sexes is by no means the norm in the animal world. To do this, instead of talking about sex, she talks about gender. She then refers to such well-known phenomena as species having two kinds of male (some big and some small, for instance), and argues that (since these kinds often follow different sexual strategies) such species have two male genders. She concludes that this shows there are many genders and hence, sexual selection cannot apply.

But what about the obvious response, that we have one sex with some members doing one thing and other members doing another thing? What about the objection that gender is exclusively a human concept referring to how we feel about our sexuality, how we identify ourselves, as in: "I was a man trapped in a woman's body." In what sense could a bullfrog (to take one of Roughgarden's examples) possibly have a sense of sexual identification?

More than this. Roughgarden points out that sometimes an animal can have one form at one stage of its life and another later in life. When these differences are connected to different sexual strategies, apparently, the two-gender label applies even here. Can this really be so? Adolescent boys have habits intended to attract females, like showing off and sports and so forth. Men over 40 have rather different habits intended to attract females, like offers of good food and wine and trips to South Sea islands. While there are days when I am quite prepared to argue that adolescents are a non-human species, I doubt they are different genders.

Second, is it not time now to move beyond listing same-sex behaviour in animals and simply labelling it "homosexuality"? According to the (1970s) Kinsey reports, human male homosexuals, particularly, are often if not usually exclusively homosexual in thought and behaviour. They really are not heterosexuals taking an afternoon off from the wife and kids. Yet the whole point of Roughgarden's alternative mechanism to sexual selection is that homosexuality is something that bonds heterosexuals to each other, so that then they can go out in a gang and grab more mates than they could acting alone. Is this really what the bathhouse culture was all about?

Third, even if she disagrees with standard theory, Roughgarden should have taken seriously the arguments of traditional evolutionists about sexual selection. If not sexual selection, then how does one explain the fact that the elephant-seal male is hugely larger than the female? If this is not a function of males competing with each other for the females, then what is it? And why do we have such sexual dimorphism when and only when males compete in this brutal way? Perhaps tradition is wrong, but it deserves a refutation.

I am afraid that sincerity is not enough. Bad arguments are bad arguments, even when written from the heart.

Michael Ruse is Lucyle T. Werkmeister Professor of Philosophy, and program director in the history and philosophy of science, at Florida State University in Tallahassee. He has immense respect for Roughgarden's science. Copyright 2004 Toronto Globe and Mail