What does it mean when your stomach rumbles? How do our bodies extract nutrients and vitamins from food? Does what you eat affect your mood? Digestion is an invisible, effortless, unconscious process—and one that, until recently, we knew almost nothing about. On this episode of Gastropod, we follow our food on its journey to becoming fuel, from the filtered blood that helps slide food into the stomach to the velvet walls and rippling choreography of the small intestine to the microbial magic of the colon and out the other end. And we do it by visiting the world’s most sophisticated artificial gut at dinnertime—a plumbing marvel named TIM that chews, swallows, squeezes, farts, and poops just like the real thing.
Before the invention of refrigeration, cadavers that early scientists dissected to learn about human physiology usually had their gut removed, to help reduce the stink. As a result, the digestive system largely remained a black box—food went in; the processed remains came out—until a window opened into that black box in 1822, in the form of a bullet hole in Alexis St. Martin’s stomach. An impoverished French Canadian trapper, St. Martin worked for the American Fur Company until he was accidentally shot. As Mary Roach, the author of Gulp: Adventures on the Alimentary Canal, told Gastropod, a surgeon named William Beaumont discovered that the bullet hole offered a literal opening into the mysterious workings of the stomach, because St. Martin’s “breakfast kind of spilled out.” Roach said it’s unclear whether Beaumont did his best to heal St. Martin: “He says that he did. But, I’m just guessing, maybe he kind of saw an opportunity here.”