For someone who never set out to write about science, Mary Roach has certainly proven herself up to the task. More specifically, Roach has become something of an expert at exploring weird, uncomfortable, sometimes taboo questions — from how quickly a cadaver decays to how paraplegics can achieve orgasm — and doing it with an unmistakable combination of candor and comedy.

Her new book, Gulp, takes readers through the alimentary canal to explore the science of human digestion. Along the way, Roach samples rancid olive oil and whale skin, shoves her hand inside a living cow’s stomach, and follows a human fecal transplant (it’s exactly what it sounds like) from donation to insertion. We caught up with Roach to learn more about the ins and outs of science reporting, the weirdest facts about digestion, and how she decides which far-out topics merit the signature Roach approach.

What got you hooked on writing about science, instead of spending your career covering something else?

To be honest, it turned out that science stories were always, consistently, the most interesting stories I was assigned to cover. I didn’t plan it like this, and I don’t have a formal background in science, or any education in science journalism. Actually, I have a bachelor’s degree in psychology. But whenever I got a call about doing a science story, I was always drawn to the assignment. I guess for me, it’s sort of like being in continuing education classes all the time. You’re always learning something new, and that’s what I really like about it.

You just finished Gulp, a book about digestion. What was the weirdest thing you learned in the reporting process?

Keep in mind that I come into these things with no background, so everything I learn is pretty shocking and weird to me. But I was really surprised to find out that we have a second set of nostrils, in the backs of our throats towards our nasal passages. When we chew, some of those [ed: airborne] molecules actually enter this nose and help our brain figure out what we’re eating. I really like wine and gin, so now whenever I drink either one, I try to exhale with my nose when I have some in my mouth. It makes a huge huge difference in what you can taste.

What’s the toughest part about science reporting for you?

"I come into a book with the same sense of awe as my readers."

Hands down, the fact that I don’t have a degree in any type of science. I’m always on thin ice with getting stuff straight. Even if I have the basics, or all the little pieces of a story, I’m always at risk of missing some big part or misstating some important detail. When I’m done a book, I always give it to someone with expertise in the topic and tell them to flag all of my stupid mistakes.

At the same time, this means I come into a book with the same sense of awe as my readers. I’m discovering all of this stuff with them at the same time, this feeling of "holy shit, I cannot believe that!"

You certainly seem to pull it off. Which means other writers want to know: how do you work? What’s a day in the work life of Mary Roach?

I work out of a little office with 11 other writers and a few people in the radio business. We share office space in downtown Oakland, and that’s where I do my research and my writing if I’m not out on a reporting trip. I have a nice little office, with a nice little window in it, but I do basically spend huge amounts of time in what you could consider solitary confinement.

"I’m basically a professional pesterer."

I usually work Monday to Friday, 9-to-5 banker’s hours, but not because it necessarily has to be that way. I guess that just makes it easier, because those tend to be the hours that the rest of the world is working.

I spend a lot of my time on the phone, pestering people. What’s new in your lab? Can I come visit your lab? When can I come visit your lab? I’m basically a professional pesterer.

Your books have run the gamut: space, sex, digestion. How do you decide what topic to devote a book project to?

It’s largely a process of elimination. A lot of interesting topics out there just won’t work for me. People have suggested that I write books about sleep, or drugs, but those are largely internal — a lot is going on inside someone’s body or inside their head — and I have a hard time making that compelling. I like scenes, events, on-the-ground reporting.

"But there’s no magic potion for coming up with the right idea."

A topic really has to be broad enough so that I can cover a bunch of research and a lot of different angles, but it also has to be appealing to a lot of readers, because publishers like selling books. And let’s face it, so do writers. But there’s no magic potion for coming up with the right idea; you can’t just sit down and decide that you’ll find it in the next two hours. It often just pops up right under my nose, or in the case of Gulp, I guess it popped up inside my nose.

If you had to pick, what’s the one scientific breakthrough you most hope to see in your lifetime?

I get really excited about specific therapies, personalized therapies. Like, let’s say taking a piece of someone’s tumor and testing a bunch of treatments in a lab and being able to come up with the right therapy for that specific patient. Right now it’s still really expensive and it might still be a ways off, but I think we’re on the verge of a huge breakthrough right now. Who knows how long it’ll be, but that’ll be a big day. And I think that’ll be pretty amazing.

Speaking of digestion, let’s say you have to pick your last meal. Right now. What is it?

We’ll start with 12 oysters from pretty much anywhere, as long as they’re fresh. Then I’d have to have beef pho, with the raw beef that you put into the soup yourself and let it cook as long as you want it to. And somebody’s gotta do a good job on the broth, because this is my last meal. Then I’d have a few al pastor tacos from the Sinaloa taco truck in Oakland, where I live. And some really good ribs.

For dessert, a perfectly fresh mango and some perfectly fresh cherries. But I don’t care so much about dessert; I’d rather save myself for the main courses.

Finally, a very, very dry martini, because I need to be a little bit drunk before the executioner pushes the button, or whatever he’s going to do to me.

Image credit: Chris Hardy Photography