Writer Mary Roach's bestsellers Stiff and Spook explored the science of corpses and the afterlife. In her latest book Bonk, the investigator examines the science behind sex -- the how, why and what of getting it on. Not content to sit on the edge of the bed, Roach (with her husband Ed) put herself under the microscope, recording the details as a doctor waved an ultrasound wand over the couple while they had sex. Playboy.com contributor Joel Reese talked to the author about the experience, and what she learned while piecing together the ins and outs of everybody's favorite pastime.

Playboy.com: Have you uncovered the secret to helping the average guy with his sex life?
Roach: There was that amazing study by Masters and Johnson in which they brought in gay people, straight people, long-term partners and basically people who hadn't met each other. They looked at who was having the best sex. It seemed that gay partners were having the best sex by just losing themselves in the moment and being aware of how what they were doing affected their partner, and letting that arouse them. In other words, pleasing the other person is what turned them on. It wasn't like, "Ok, first you do me, then I do you." It's hard to put it into a list of tips, but it's basically being more in-tune with your partner.

Playboy.com: Do you believe that men can be multi-orgasmic?
Roach: Yeah, sure. There was a study done at SUNY-Downstate where they talked to, I think, 21 men. These were all multi-orgasmic men, and some had been this way their whole lives, others had come upon it later in life. Because they kept going on behalf of their partner and -- lo and behold! It was pretty well-documented.
 

Playboy.com: Other than the one account of having sex in the lab with your husband, there's very little mention of your own experience.
Roach: That was a "too much information" issue. The book isn't about me, it's about science. And I'm not a scientist. It didn't really seem appropriate, except when I was a subject in a study. That scene where Ed and I are scanned with an ultrasound -- that was a writing challenge. When I turned in the book, my editor said, "I don't even know if this should be in the book. We want people to take you seriously and not think you're trying to be salacious just to sell books." But my agent said, "There's not enough detail here!" So I was trying to draw the line between people's obvious curiosity about what it's like, but not make the reader cringe and think, "You know, I don't need to be following Mary Roach that closely."

Playboy.com: So I take it you didn't have an orgasm during this particular encounter.
Roach: Hell no! [Laughs] First of all, it's like my least favorite position. We were spooning, lying on our sides. As you can see from the ultrasound, it hits you right in the bladder in that position. And the other thing is -- and I've never mentioned this amount of detail to anybody -- I was told to drink some tea because liquid is a good conductor of ultrasound waves. So it was really uncomfortable. I was taking notes, very distracted, just trying to get through it. And Ed had taken a Viagra. 

Playboy.com: So was Ed able to finish the job?
Roach: Yes, he was. After Dr. Deng said, "You can ejaculate now," he then said, "But you don't have to." Ed said, "Do you want me to?" and Dr. Deng said, "Yeah, sure." But we cut that out of the book. My agent said, "Ok, enough with the details."

Playboy.com: Part of the excitement of sex is the mystery. Did studying sex remove that for you?
Roach: That's why I wanted to end on a non-mechanical note. Even though sex is a biological, physiological and even mechanical process, that stuff is not the most important. It has much more to do with the two people who are having it and how in-tune they are and where their heads are at. [The Masters and Johnson study Homosexuality in Perspective] is the only study I could find that dealt with that aspect of it, which I think is hugely important. When I was reading Masters and Johnson's Human Sexual Response, there's so much detail about exactly what happens in all the different body parts. And if you think about that while you're having sex, it's really distracting: "Hmm, am I at that point where the vaginal platform is expanding?" "Is this the part where there is a flush across the chest?" There's a bunch of stuff that's useful and helpful, but it tends to just get you focusing on clinical and mechanical stuff, when you really want to be losing yourself in the moment.

Playboy.com: But you've forgotten it to the point where it doesn't distract you now?
Roach: Yeah, it was a phase that lasted a few weeks. It was specifically that [Masters and Johnson] book, because it's such an amazingly detailed book. You're like, "Holy shit, I didn't know that happened!" For instance, at a certain point of arousal, the clitoris retracts from view. That's a piece of information that could be helpful for a man -- or a woman -- to know. Because it could be confusing: "Hey, where'd it go? I can't find it!" And digging around for it could be sort of uncomfortable.

Playboy.com: You note there are many animal species in which the males have many different partners, and the females are okay with that.
Roach: Yeah, just about all of them. I spent the day at the Yerkes National Primate Research Center, and there are a couple of alpha male monkeys, and a bunch of female monkeys. And the males are mating with anybody who's ovulating, and everybody is fine with it. The females are really just interested in sex when they're ovulating -- otherwise, they completely ignore the males. They don't care who the males are screwing. I think monogamy is the exception.

Playboy.com: So why doesn't that work for humans?
Roach: Oh God, I think that's a whole other book! [Laughs] There are whole books of the evolutionary biology of monogamy and promiscuity -- that's really kind of out of my territory.

Playboy.com: Has Viagra affected the sexual dynamics between men and women?
Roach: When Viagra came out, there were demonstrations -- both overseas and here -- from older post-menopausal women, saying basically, "We deserve a rest! My husband wants to have sex all the time now that he's discovered Viagra!" But there was a study when they looked at the reasons people visited a sexual dysfunction clinic. And it was something like 80 percent of the women were there because of low libido. They had no sex drive, and their husbands were frustrated by it, they were frustrated by it. But that was never the problem with the men -- 62 percent of the men were there because they couldn't get it up. So there's not a lot of overlap. And right there, you've got a recipe for disharmony. And there are plenty of post-menopausal women who are delighted their husbands can now "achieve and maintain," as they say. I would say, if you look at the number of people who look at Viagra as a godsend versus those women who were quoted in Ann Landers saying "We've all earned a rest!," it's probably 10 to 1.