Michael Baum, a biologist at Boston University, got a more detailed look by studying ferrets, whose biology is well understood. He has shown that the anterior hypothalamuses of gay and straight ferrets—as well as of male and female ferrets—are also of different sizes. The structural distinctions have clear behavioral consequences. Ferrets find their mates primarily by odor. Using a “reporter gene,” Baum proved that a receptor in the anterior hypothalamus responds differently to the same odor depending on the sex of the ferret. Creating a lesion in that part of the brain can make a male ferret approach other males. Baum also finds that administering the right steroids early in life can reverse the animals’ sex response: Female ferrets dosed with testosterone early in life act masculine.
Odor does not affect us as much as it does ferrets, but that is not to say that odor doesn’t influence our sexual response. Ivanka Savic Berglund, a neuroscientist at the Karolinska Institute in Stockholm, put gay men, straight men, and women in a PET scanner (not all at the same time) and watched how their anterior hypothalamus lit up when presented with an odor similar to one found in men’s sweat and one similar to a scent found in women’s urine. The gay men’s brains responded the way the women’s brains did. “I was so pleased when I saw the paper—it kind of made my day,” says Baum. “But I think it would have been great if she had used real sweat.”
So is brain development the final frontier for seeking the source of homosexuality? “At first blush you might think, ‘Well, gosh, maybe gay men didn’t get enough testosterone early in life,” says Marc Breedlove, a neuroscience professor at Michigan State University. “But as we find markers that should tell us about prenatal testosterone, they haven’t shown a consistent pattern.” Such studies are puzzling for Breedlove, who has spent much of his career proving that for animals things really are that simple. Castrated male rats given ovarian steroids as adults go straight for other male rats, while others given testosterone still flirt with females (however futile their propositions). “We can cause animals to be as masculine or feminine as we want by manipulating their exposure to testosterone,” he says. “If I take a female rat pup and I give her just one dose of testosterone, in a few hours that testosterone is gone, and yet for the rest of her life she’s masculine.”
Lab rats are easier to manipulate than people, however. “I love my rats,” says Breedlove, “but they’re not very complicated.” Apparently, humans are unlike the rest of the animal kingdom. Still, low testosterone or high testosterone could up the chance that a boy would grow up to be gay. No experiment has yet ruled that out.
If researchers do prove that testosterone can alter human sexual orientation—gay gene or no gay gene—the possibility of preventing homosexuality will become a reality. Even a hint of that option is enough to provoke an outcry among activists. Recently word got out that Charles Roselli, a physiologist at Oregon Health and Science University, was trying to find out how hormones affect the brains of gay sheep. PETA roped tennis star and lesbian activist Martina Navratilova into writing a letter to the university, calling the research homophobic and cruel. She accused the researchers of trying to find a “prenatal treatment for various sexual conditions.”
What drives the sex researchers (some of whom are openly gay) is most often pure curiosity. They just want to know. “People whose motivations are political don’t comprehend that anyone could be interested in why,” says Ray Blanchard. And that why isn’t just a why for homosexuality but a why for sexuality, period.
“I can’t focus enough on how these are not gay genes—these are straight genes,” Bocklandt says. “If you want to find a gene that makes you see colors, you compare the genes of people who see colors with the genes of people who are color-blind. They’re not genes for color blindness. What we’re talking about here is the most basic thing, the most basic question. Why does a crocodile recognize the opposite sex and want to f**k?”
