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January 05, 2005

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Publication Date: Wednesday, January 05, 2005

Darwin revised Darwin revised (January 05, 2005)

Stanford biologist challenges long-held theories on evolution

"Evolution's Rainbow: Diversity, Gender, and Sexuality in Nature and People," by Joan Roughgarden; University of California Press; 474 pp.; $27.50.

by Jennifer Dietz Berry

Belief in Darwin is almost as fundamental to some as belief in Jesus is to others.

I can remember as a teenager coming across a "Darwin fish" being hawked by one of the street vendors in Berkeley as an alternative to the "Jesus fish." I bought one and slapped it onto the trunk of my car. It was meant to be funny, but I also put it there to show I believed in reason, logic and science over the type of blind faith I associated with religious fundamentalists.

It never occurred to me that my faith in Darwin might be just as blind. But this is exactly what Stanford Biology Professor Joan Roughgarden suggests in her controversial new book, "Evolution's Rainbow."

This is the first book Roughgarden has written for a general audience, and it has caused a stir both for its science and its politics. Within the first few pages, Roughgarden launches an attack on Darwin, claiming his theory of sexual selection is inaccurate and inadequate, useful only as a historical artifact.

But what may be even more controversial is her conclusion that homosexuality is not, as many have tried to argue an exception to the norm. According to Roughgarden, homosexuality is a behavior that over the course of evolution has been actively selected for both humans and animal species. In other words, homosexuality is natural.

In an environment where scientists often like to be thought of as distant and objective, Roughgarden freely acknowledges the impetus for writing the book is rooted in her personal experience as a transgendered woman. Darwin convinced many of us there was only one natural model for reproduction in the animal kingdom. Females of the species were supposed to be coy, having sex infrequently and choosing only the best males to reproduce with, while males were supposed to be competitive and promiscuous, battling against one another for the right to copulate with as many females as possible.

Unfortunately, it implied that people like herself -- people who don't fit neatly into Darwin's male and female roles -- were somehow "unnatural."

She remembers attending her first Gay Pride Parade in San Francisco back in 1997. Her name was Jonathan then and she was months away from undergoing surgery to become a woman. She was worried about what the future might hold and what impact her decision might have on her Stanford career. But she was also looking at the crowds on Market Street and formulating ideas.

"When we go outside and look at animals we assume the animals are taking actions that are beneficial to them, so if we see homosexuality in a species of primates we don't assume there's something wrong with that species," Roughgarden said. "We assume that the homosexuality within that species has some adaptive function. Otherwise it wouldn't be there."

"That's why it was a red flag to me to see so many people there," she continued. "The statistic of 1 in 10 being gay is an interesting statistic, but it's just a number. When you see a hundred thousand people lining both sidewalks on Market Street going all the way to the ferry building, then you know that, hello!, there's a problem here.

"... If there's a theory that says there's something wrong with so many people, it could be the theory that's wrong."

Part of the reason homosexuality has been considered by some to be "unnatural" is rooted in sexual selection theory. If, as Darwin argues, only those traits that increase "reproductive fitness" are selected, then it becomes difficult to explain why homosexuality should exist at all. From that vantage point, it's easy to see why biologists or physicians might be inclined to think of it as a genetic defect or a pathology -- a disease in need of a cure. However, as Roughgarden surveyed courtship rituals in the animal kingdom, she found there was much more diversity than science classes have led us to believe.

From here, Roughgarden began to wonder if boiling down everything that goes on in the animal kingdom to sexual reproduction might be underestimating the complexity of the societies animals have created. Could it be that certain traits are selected in animals, not because they necessarily improve the animal's sexual fitness, but because it is a trait or a behavior that helps the animal gain acceptance into a group that controls resources or offers a protected environment to reproduce and raise offspring?

Take, for instance, the bonobo. These primates are known to have both heterosexual and homosexual encounters multiple times a day. In this case, homosexuality and promiscuity appear to have an adaptive function. Sex acts are used not only for reproduction, but also as a means of minimizing conflict and encouraging sharing and cooperation among the animals in ways that seem to benefit the entire group.

Roughgarden coined her revisionist view of sexual selection as "social selection theory." And she believes it is only a matter of time, maybe 20 years or so, until sexual selection theory is discarded in favor of something closer to the model she describes. But she also knows her peers in academic and scientific circles aren't likely to toss out Darwin without a fight.

"To a sexual selection researcher, the idea that sexual selection theory is false is like saying the sky isn't blue," Roughgarden says. "It's so counterfactual that it's almost preposterous."

Not surprisingly, Roughgarden's book has received its share of criticism. Some scientists have been uncomfortable with her approach, wondering whether her strong personal views might have hampered Roughgarden's ability to look at the science objectively. Others say there aren't enough exceptions to Darwin's male and female templates to justify throwing out the theory. And still others have challenged Roughgarden to back up her theory with more evidence and more research.

It's a challenge Roughgarden is more than willing to embrace. "You just do what you have to do," she said. "I feel very privileged to be in a position to have done this research. Most of my transgendered brothers and sisters are unemployed or working in the sex trade or something like that, and here I have, still, a professional job. This is not an opportunity I should squander."

Jennifer Dietz Berry is a local freelance writer and former Weekly education reporter. She now works at the Stanford University School of Medicine.


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