Best-selling author Mary Roach made a name for herself by exploring the secret lives of cadavers (in her book Stiff) and science's fascination with the supernatural (in Spook). Now, she's turned to the often-wacky researchers who are obsessed by exactly what happens when Part A goes into Slot B.

In her new book Bonk: The Curious Coupling of Science and Sex, Roach explores topics ranging from the sexual stimulation of Danish pigs and MRI scanner intercourse to bisexual bulls and the 19th century "penile pricking device" (don't ask). What did Roach discover? She tells all in an interview with Wired.com.

Wired: You've written twice before about death and science. What made you decide to look at sex and science?

Mary Roach: I was lying in bed and reading Film Quarterly, which was lying around our house. There was a reference to [sex researchers] Masters and Johnson making films using a tiny camera and a light source inside a moving phallus – the artificial coition machine.

I remember thinking, Holy shit, they made this camera and that's how they did their research – they brought subjects into the lab and documented their sexual response from the inside with a little tiny camera in a "penis."

That's when I said my next book was about sex research. I was despairing that I'd never have another idea, and there it was!

Wired: An artificial coition machine?

Roach: That was a humdinger.

It was very innovative. There were a lot of basic things about female arousal that they didn't know without seeing inside. They were able to answer a lot of questions about things like lubrication and "vaginal tenting," which is when the back part of the vagina pulls away. It was a big mystery, and they were able to literally shine a light on female sexuality.

Wired: What are some myths about sex that scientists have debunked?

Roach: There's the coital interlocking myth, which goes all the way back to Leonardo DaVinci [and his drawings of intercourse]. The idea was that when people had sex, the penis would go all the way inside the cervix, and the cervix would open like Pac-Man. There would be this thing like the space shuttle docking. If you had trouble getting pregnant, you had a bad interlock.

It wasn't until [early 20th-century American gynecologist] Robert Latou Dickinson got out his test tube and did some intravaginal spying that he discovered the penis doesn't hit the cervix but just goes right by it.

Somebody also did research disproving that the bigger your clitoris, the better your orgasms or the more arousable you are.

Wired: What was the most surprising thing you discovered in your exploration of sex research?

Roach: That women get nocturnal clitoral erections. The clitoris is sort of like a little tiny penis … I just love that they actually studied it, that they found women with especially big clitorises and got a big strain gauge and figured it out. You've got to love scientists.

I was also surprised that so many men have multiple orgasms. That was new and interesting, as was the fact that the nose has erectile tissue.

Wired: What did you learn about sex researchers themselves?

Roach: Everybody's heard of Masters and Johnson, but I don't think most people are aware of how thorough they were and just what went on their labs. Not that there's anything wrong with what went on their labs.

[For instance, they] got a woman to come in and have sex with a machine and record what was going on inside her body. And there was another study where they matched people up, assigned them to partners and had them have sex.

Wired: There's a psychoanalyst mentioned in your book named Princess Marie Bonaparte. She was a confidante of Sigmund Freud and a great-grandniece of Napoleon – but what was her role in the history of sex research?

Roach: Marie Bonaparte was extraordinary. She wasn't trained as a physician, but she interviewed all these women, and she measured the distance between the clitoris and the vagina.

She was looking for correlations between their clitorises and whether they had orgasms in the missionary position. She herself never did. She thought of herself as a voluptuous sexual woman, but she never got any satisfaction from sex. Her husband was gay, and that was a complicating factor, but she had a number of affairs and complained about them too.

She knew a surgeon, and to test her theory about the clitoris and the vagina, she had her own clitoris surgically moved closer to her vagina.

It was written up. But it didn't help. It's sad because someone should have taken her aside and said, "Try something else [sexually]." Instead, she went straight to the operating table. Those were different times.

Wired: Sex drives a lot of people bonkers. Does it do the same thing to scientists who try to understand it?

Roach: Sexual response is such an individual thing: There are people who have orgasms when they brush their teeth. There's so much individual difference that it's hard to do what science likes to do and make conclusive statements.

Wired: What do you think science hasn't figured out about sex?

Roach: That whole question of what makes the difference between a woman who easily has orgasms from intercourse and someone who never does. What is the variable? Is it emotional or mental? The G-spot? Nobody knows. There's probably no answer: It's different in different women.

Wired: Some people say that men's sexuality is like an on-and-off switch, while women's is more like an airplane's control panel with dozens of gauges and dials. Is it true that there's simply a lot more to a woman's sexuality?

Roach: That's obviously a generalization. There's a huge range of individual differences. But it's safe to say yes. Women are much more complicated.

Wired: Give me an example.

Roach: My favorite line in [Alfred] Kinsey's work was how when cheese crumbs are spread before a pair of copulating rats, it distracts the female but not the male.

[With women], the phone rings, you've got to start all over again. The conditions are more important with women.

Wired: Is science paying more attention to women now?

Roach: Big time. They've just booted men out on their asses: "We've made enough money off you [through impotence drugs]. There must be something for [women] we can cook up." That's where the attention is now.

Wired: Do you think it will take awhile before there's a Viagra – a drug that works so well in so many men – for women?

Roach: They've given up on a female analog for Viagra. A drug that boosts blood flow down there doesn't work: Women don't perceive themselves as being more aroused, even though there's more blood flow. It's that pesky mind-body disconnect.

Now they're looking at central nervous-system drugs for low libido. There's one called Flibanserin that's making its way through the FDA pipeline now.

Wired: You point out that pharmaceutical companies are taking the lead in funding sex research to treat sexual disorders. Is any kind of sex research getting neglected these days?

Roach: No one funds pure anatomical, physiological research anymore, which is sad no matter what field you're talking about.