Humans have eaten earth, on purpose, for more than 2,300 years. They also crave starch, ice, chalk, and other unorthodox items of food. Some even claim they are addicted and "go crazy" without these items, but why? Sifting through extensive historical, ethnographic, and biomedical findings, Sera L. Young creates a portrait of pica, or nonfood cravings, from humans' earliest ingestions to current trends and practices. In engaging detail, she describes the substances most frequently consumed and the many methods (including the Internet) used to obtain them. She reveals how pica is remarkably prevalent (it occurs in nearly every human culture and throughout the animal kingdom), identifies its most avid partakers (pregnant women and young children), and describes the potentially healthful and harmful effects. She evaluates the many hypotheses about the causes of pica, from the fantastical to the scientific, including hunger, nutritional deficiencies, and protective capacities. Never has a book examined pica so thoroughly or accessibly, merging absorbing history with intimate case studies to illuminate an enigmatic behavior deeply entwined with human biology and culture.