At dawn on a brutally cold January morning, the author crouched in the icy grandeur of the Teton Range. It had been three years since wolves were reintroduced to Yellowstone after a sixty-year absence, and members of a wolf pack were approaching a herd of elk. To the author's utter shock, the elk ignored the wolves as they went in for the kill. The brutal attack that followed—swift and bloody—led him to hypothesize that after only six decades, the elk had forgotten to fear a species that had survived by eating them for hundreds of millennia. The author's fieldwork that frigid day raised important questions that would require years of travel and research to answer: Can naive animals avoid extinction when they encounter reintroduced carnivores? To what extent is fear culturally transmitted? And how can a better understanding of current predator-prey behavior help demystify past extinctions and inform future conservation? This book is the chronicle of the author's search for answers. From Yellowstone's elk and wolves to rhinos living with African lions and moose coexisting with tigers and bears in Asia, the author tracks cultures of fear in animals across continents and climates, engaging readers with a combination of natural history, personal experience, and conservation.