Summary
In "Gulp," Mary Roach takes us on a fascinating and often hilarious journey through the human digestive system. From the moment we inhale the aromas of a delicious meal to the final, unsavory act of excretion, Roach explores the science, history, and cultural quirks of everything that happens to our food once it enters our bodies.
The book begins with the nose, the unsung hero of flavor. Roach visits a sensory analyst who can identify dozens of aromas in a single sniff, demonstrating how much of what we perceive as taste actually comes from our sense of smell. She then delves into the world of pet food, where scientists use "palatants" to entice our furry friends to eat nutritionally complete but otherwise unappetizing kibble. Roach even tries some of these palatants herself, discovering that what tastes good to a cat may not taste good to a human.
Roach explores the cultural influences that shape our food preferences, traveling to the Arctic to meet Inuit elders who consider raw caribou eyes a delicacy. She recounts the U.S. government's attempts to persuade Americans to eat organ meats during World War II, a campaign that ultimately failed due to deeply ingrained cultural biases.
The journey continues through the stomach, where Roach learns about the surprisingly powerful digestive juices that break down our food. She explores the history of digestion research, including the infamous William Beaumont and his experiments on Alexis St. Martin, a man with a permanent hole in his stomach. She then moves on to saliva, revealing its surprising antimicrobial properties and its role in wound healing.
Roach explores the mechanics of chewing and swallowing, visiting an oral processing lab where scientists study bolus formation. She delves into the world of competitive eating, learning how professional eaters can consume massive quantities of food without feeling full. She also investigates the darker side of the digestive system, exploring the use of the alimentary canal for smuggling contraband and the dangers of flammable flatulence.
The final chapters explore the mysteries of constipation and the surprising benefits of gut bacteria. Roach learns about the dangers of autointoxication, a debunked theory that blamed many health problems on the absorption of toxins from the colon. She also visits a gastroenterologist who performs fecal transplants, a surprisingly effective treatment for chronic infections. Roach ends the book with a look at the evolution of the digestive system and its remarkable complexity.
"Gulp" is a captivating exploration of one of the most essential and often overlooked parts of the human body. Roach's engaging writing style, combined with her knack for uncovering unusual stories and fascinating scientific facts, makes this book a truly unforgettable read.