Guts and Glory: Mary Roach Tackles Digestion

A literary exploration of the digestive process.

Mary Roach tackles digestion in her new book "Gulp."

If your last name was Roach, you might not celebrate that fact. You might not, for example, have a website in which a seemingly life-sized illustration of the commonly loathed insect crawls across the page until it rests, antennae still wagging, smack-dab on your name. Not Mary Roach. The outrageously funny science writer who has tackled subjects like cadavers in "Stiff" and sex in "Bonk" has applied her trademark wit and candor to taboo with her latest book: "Gulp," everything you (never) wanted to know about digestion.

Here, she travels the world to canvass the circuitous course that food takes in one's body, from entrance to exit, stopping to survey why, what and how we eat and excrete. And she does this with a tone that's as familiar and often funny as the subject itself. She's arguably at her wittiest in the footnotes peppered throughout the book that read like class-passed notes or an aside by a very funny friend.

To explain how one's tastes reflect one's culture, she documents the predilection for organ meat among the Inuit, or Eskimo, people, as a function of supply and demand. "Organs are so vitamin-rich, and edible plants so scarce, that the former are classified, for purposes of Arctic health education, both as 'meat' and as 'fruits and vegetables,'" she says. In fact, when she visited in 1993, "cucumbers were so expensive that the local sex educator did his condom demonstrations on a broomstick."

[See Teaching Your Kids About Sex: Do's and Don'ts.]

Meanwhile, she enlightens with answers to some of humankind's most persistent and embarrassing questions. For example: "The simplest strategy for bouts of noxious flatus is to not care. Or perhaps to take the advice of a gastroenterologist I know: Get a dog. (To blame.)" She goes on to name foods that one might otherwise avoid, but adds that these offerings—beer, garlic and some spices, among them, include "so many delightful things that a sane person would, I like to think, rather have the gas."

Still, in explaining the capacity of the rectum for smuggling contraband or the success of fecal transplants to rid patients of desperate infections, she writes with unmistakable reverence. "People who understand anatomy are often cowed by the feats of the lowly anus. 'Think of it,' said Robert Rosenbluth, a physician whose acquaintance I made at the start of this book. 'No engineer could design something as multifunctional and find-tuned as an anus. To call someone an a--hole is really bragging him up.'"

Below, she tells U.S. News about her latest excavation:

What were you most astonished to learn about in your research? What were some of the discoveries that really blew your mind?

I was astonished by the extent to which visual information trumps taste and flavor. There's a famous study from a university in Bordeaux, France, in which wine experts are presented with a red and a white wine, and asked to describe them. Then they're given a second set of red and white, but the "red" this time is actually the white, with a red color added. Now the experts used white wine descriptors. [I'm] also amazed by the extent to which we eat with our ears. If you give someone chips to eat and you experimentally alter the frequency of the sound of the chips fracturing, they will say that the chips are stale. This blew my mind: The sound of a chip cracking is a tiny sonic boom in your mouth.

[See Fresh Fish Shouldn't Stink, and Other Rules of Thumb.]

Has your research affected your own choices of what or how you eat? Has it made you squeamish about certain foods or more awed by the digestive process?

Since researching the nose chapter, I use my internal nostrils when I eat or drink wine or gin. (I do like a good martini.) That is, I practice retronasal olfaction, exhaling while I hold the food or drink in my mouth. This wafts the flavor molecules up into the top of the nasal cavity and enhances the experience of what you're consuming. But don't do it too briskly, because you can blast the food or wine up into your nose. The technical term for this, you may be delighted to know, is nasal regurgitation.