Roach explores the science of chewing and oral processing at Food Valley, a research hub in the Netherlands dedicated to food science. Her investigation begins with Andries van der Bilt, an oral physiologist who studies mastication using silicone cubes that research subjects chew to measure their individual chewing effectiveness. Roach discovers that people possess unique chewing patterns as distinctive as fingerprints, with some individuals requiring as few as 17 chews to eat peanuts while others need 110.

Van der Bilt’s research reveals the remarkable sophistication of human jaw mechanics. The jaw muscles represent the body’s strongest muscles in terms of pressure, yet they possess an intricate protective system that prevents self-injury. When crushing food, the jaw automatically reduces force the instant an object breaks, preventing teeth from colliding destructively. This reflex, called the “silent period,” demonstrates extraordinary sensitivity: Human teeth can detect particles as small as 10 microns in diameter.

The chapter examines the broader field of oral processing research, which studies how food transforms into a “bolus”—the chewed, saliva-moistened mass ready for swallowing. Roach notes that this scientific area faces declining interest, partly due to the unappetizing nature of studying partially processed food. She illustrates this disgust through the historical case of Tom Little, an Irish-American man who suffered an esophageal injury as a child and spent his life chewing food but spitting it into a funnel connected to his stomach.

Roach explores dysphagia, a swallowing disorder that affects stroke patients and others with neurological conditions. The research has practical applications for creating safer foods for people with swallowing difficulties. The chapter also addresses the psychology of texture preferences, explaining why humans crave crispy foods. Ton van Vliet, a food physicist, explains that crispiness signals freshness through cellular structure—fresh foods contain air-filled cells that burst audibly when bitten, creating the satisfying crunch that indicates quality and safety to humans’ evolutionary-trained senses.

Roach explores the biological possibility of surviving inside a whale’s digestive system, using the biblical story of Jonah as her starting point. She examines whether different whale species could actually swallow and sustain a human being.

Roach explains that baleen whales, despite their enormous mouths, possess extremely narrow throats that make swallowing humans impossible. Sperm whales, however, have gullets wide enough to accommodate a person and feed through powerful suction rather than chewing. This anatomical difference makes them the only viable candidates for such scenarios.

The author investigates the famous 1896 case of James Bartley, a sailor allegedly swallowed by a sperm whale near the Falkland Islands and recovered alive after 36 hours. Though this story appeared in the New York Times and became popular among religious fundamentalists, historian Edward Davis later proved it completely fabricated through extensive research.

Roach then examines the physiological challenges of surviving inside a whale’s stomach. While sperm whale stomachs are spacious enough to house a human, they function like powerful grinding mechanisms, exerting crushing forces comparable to bird gizzards. French scientist René Réaumur’s 18th-century experiments with birds demonstrated that gizzards generate nearly 500 pounds of pressure, sufficient to crush glass and metal tubes.

The chapter addresses the persistent myth that living tissue possesses some protective force against digestive acids. Eighteenth-century anatomist John Hunter theorized that living organisms couldn’t be digested while alive, but French physiologist Claude Bernard disproved this through experiments involving live frogs and dogs. Roach explains that stomachs avoid self-digestion not through mystical protection but by constantly regenerating their protective lining every three days.

Finally, Roach examines historical medical cases of patients claiming to harbor live animals in their stomachs—snakes, frogs, and lizards allegedly consumed from contaminated water sources. These phenomena, popular from the 17th through 19th centuries, were typically misdiagnosed digestive disorders. Physicians like J. C. Dalton conducted experiments proving that slugs and salamanders died within minutes of entering digestive systems, debunking these persistent medical myths that combined psychological delusion with ordinary gastrointestinal symptoms.