Bill Schutt makes a surprising case: it is teeth that are responsible for the long-term success of vertebrates. The appearance of teeth, roughly half a billion years ago, was an adaptation that allowed animals with backbones, such as fish, amphibians, reptiles, birds, dinosaurs and mammals—including us—to chow down in pretty much every conceivable environment. And it’s not just food. Tusks and fangs have played crucial roles as defensive weapons. Early humans employed their teeth as tools to soften tough fibers and animal hides. Our teeth project information and social status. So much of what we know about life on this planet has come from the study of fossilized teeth. In his signature witty style, he shows us how our continued understanding of teeth may help us humans through current and future crises, from Alzheimer’s disease to mental health issues.