The ever-curious and always bestselling Mary Roach takes us down the hatch on an unforgettable tour of our insides. The alimentary canal is classic Mary Roach terrain: the questions inspired by our insides are as taboo, in their way, as the cadavers in Stiff and every bit as surreal as the universe of zero gravity explored in Packing for Mars. Why is crunchy food so appealing? Why is it so hard to find names for flavors and smells? Why doesn't the stomach digest itself? How much can you eat before your stomach bursts? Can constipation kill you? Did it kill Elvis? We meet scientists who tackle the questions no one else thinks -- or at least has the courage -- to ask. And we go on location to a pet food taste-test lab, a bacteria transplant, and into a live stomach to observe the fate of a meal. Like all of Roach's books, Gulp is as much about human beings as it is about human bodies.