Robert Sapolsky explains how the stress response that evolved to help us escape predators now damages health in the absence of predators, as modern humans activate the same physiological systems in response to traffic jams, work deadlines, and social anxiety. Sapolsky, a neuroscientist and primatologist at Stanford who has spent decades studying stress in baboons, writes with wit and accessibility about glucocorticoids, the hippocampus, and the immune system. Unlike zebras, who experience stress briefly when lions attack and then return to baseline, humans can generate stress responses simply by imagining future threats, rehashing past humiliations, or reading the news. This chronic activation produces the diseases of modernity: cardiovascular problems, immune suppression, depression, impaired memory, even accelerated aging. Sapolsky examines how stress interacts with personality, social status, and childhood experience, explaining why some individuals are more vulnerable than others. He explores why poverty is stressful independent of material deprivation and how lack of control amplifies stress's damage. The book's final chapters examine interventions: exercise, social support, meditation, and the psychological reframing that can modulate stress response. Sapolsky writes for general readers while maintaining scientific rigor, producing a guide to understanding our bodies that is both alarming and empowering.