Darwinism is not the only research tradition in evolutionary biology, but to date it is the most empirically successful. This book explores why, and why this is still true. David Depew shows how Darwinian evolutionary biology got off to a bad start by identifying natural selection with survival of the fittest -- which led to persistent misunderstandings; how it got back on track by the mid-twentieth century; and how it faced more difficulties at the turn of the twenty-first century, including challenges about how development, ecology, culture, and genetics are related. The book ends by exploring the promises and perils of genetic biotechnology. Depew's clear and accessible discussion draws on the work of evolutionary biologists, evolutionary anthropologists, historians of biology, and philosophers of biology, and the result is a compelling interdisciplinary guide to the past, present, and future of an immensely powerful concept.