ORGIES can alter the brains of rats. Male rats, that is. No one has taken the time to find out what happens when female rats outdo themselves. And male fruit flies lust at their peril – all that wooing means a life cut short. You may well ask how flirtation and seduction affect female longevity. Er, sorry, not sure. From false penises to orgasm timers in the brain, almost all the really juicy sex stories seem to be about males.
It could have something to do with the way sex has traditionally been studied, says Jill Becker of the University of Michigan in Ann Arbor, who specialises in the neurochemistry of sexual motivation. She puts it down to one thing – male researchers. Becker is one of a new breed of scientists trying to redress the balance. By making females the subject rather than the object of experimentation, they are slowly liberating the world of sex research.
For years experimental biologists assumed that female sexual behaviour was not very interesting. It was basically about being "receptive". When the hormones gripped her, she suddenly found herself stranded in heat, locked into a sort of self-imposed missionary position. Perhaps the misunderstanding stemmed from the simple desire of sympathetic male researchers to make things as comfortable as possible for their subjects. When studying rats, for instance, typically they would start by introducing the male to his new little love nest – a 20-gallon aquarium with a carpet of wood chips – and leave him alone for a while to make himself at home. Then they would toss in a receptive female.
Three parts male fantasy, one part science, the researchers chronicled the activities of the randy rodents. Boldly the male pinned the female down. He copulated with her copiously – about twice a minute for ten minutes. She submitted, the hormone oestrogen forcing her into a reflexive sexual posture called lordosis, found in a lot of lower mammals. Her ears wiggled, her back arched in just the right way, and the male did his thing. And there you have it: rat sex.
"As much as many men I know would like to think it's the whole story, it's not," says James Pfaus at Concordia University in Montreal, who studies what turns sexual behaviour on and off. If you take the rodents out of this artificial rape chamber, and give female animals the opportunity to run away, they do. But it's more complicated than that. Running away turns out to be part of rodent sex play. The deal is, she keeps coming back.
Far from playing a purely passive role in sex, female rats are real teases, soliciting and enticing the males. "They actively approach him, crawl over him, kick him in the face, then run away," says Pfaus. The male then has to catch her. "It starts and ends not with the penis, but with her desire," he says.
This mating game, dubbed "pacing", was first seriously studied two decades ago by Martha McClintock and Norman Adler from the University of Pennsylvania. They showed that by making the male hold off, the female rat gave herself time to allow a neuroendocrine response to kick in, increasing her likelihood of becoming pregnant.
Enlightened researchers have now devised laboratory love nests that cater for the female's needs. At Boston University, Mary Erskine came up with a special two-chamber cage with a Plexiglas wall dividing the two halves. The wall has a hole so small only a female can squeeze through. Erskine found the gals would pop back about every two minutes. Further research revealed that given four holes, she would tramp back a bit more quickly; the single hole was perpetually plugged by the overeager male and she had to waste time dislodging him. Pfaus has developed a two-storey cage with multiple ramps and landings. "The female imposes an interval by running from level to level," he says.
Setups like these allow scientists to study female sexual behaviour more accurately. Pfaus is looking to see how drugs like Haloperidol and Prozac affect sexual behaviour in females; the effects in males, of course, were studied long ago. His preliminary findings suggest that Prozac knocks out lordosis altogether. Becker is sampling the specific brain chemicals sloshing around during female pacing. Alas, as yet there is no rodent model of female orgasm. "I don't think anyone's figured out how to look for it," she says.
But new notions about rodent female sexuality are emerging – that they like to be in control and, more controversially, that they even enjoy sex when they are. Two years ago, for instance, Raul Paredes from the Universidad Autonoma near Mexico City showed that after a female has copulated once in a two-chamber cage, where she sets the pace, and once in a standard cage, where she doesn't, she will go back to the split cage for more. "She tended to prefer copulations that were under her control," says Pfaus.
It is not just rats that have been fundamentally misunderstood all these years, however. Our cousins, the monkeys and apes, also fell victim to badly designed studies. Kim Wallen, a psychologist at Emory University in Atlanta, chalks it up to an accident of economics. For years, the only data on amorous relations between monkeys came from observing a single male and a single female interacting in a small cage – the only setup most institutions could afford. When two monkeys are left alone in a cage, the male takes charge in sexual interactions. The environment skews everything, says Wallen.
He realised there was a problem back in the 1980s when he began observing monkeys in a semi-natural state at Emory's Yerkes Primate Center. There females would actively pursue the males – but only for the few days of their cycle when they could conceive. At other times females tend to ignore males, and hang out with their girlfriends. "The only time a female is within two metres of a male is when she wants to have sex," says Wallen. "What we had done accidentally is put animals in a context where the male thought the female was interested."
Most researchers insist that the situation has improved in the past decade or so. But research into female sexuality is lagging pitifully behind in one species. "If I had to identify an area where we really need a lot more studies on sexuality, it's in humans," says Wallen. Pfaus went to a conference in Taiwan last year and was amazed. "Eighty per cent of the talks were about erections. What about the females?" He points out that most of the research is driven by drugs companies that want to solve male erection problems, not female orgasm problems.
One rare and intriguing study looked at a woman's hormonal state and the percentage of skin showing when she went out on the town. The research found that as a woman neared ovulation, she would expose more flesh. Hormones seem to compel her to take more social risks. And social risk can lead to sex. "The most interesting stuff goes on when people don't have partners," says Wallen. And he points out that almost everything we know about human sexual relations comes from studying heterosexual couples. A single male and a single female trapped in too small a cage, perhaps?