Draws on the principles of evolutionary biology to formulate a new way of looking at medicine: Darwinian medicine. Nesse, a psychiatrist, and Williams, an ecologist, use this evolutionary approach to offer a new perspective on human vulnerability and to explain how and why we respond to injury and illness. They argue that illness as well as the factors that predispose us toward it are subject to the same laws of natural selection that otherwise make our bodies such miracles of design.