Psychological hedonism - the idea that people tend to act in ways that maximize pleasure and minimize displeasure - has a decidedly poor reputation among academics who study human behavior. Opinions range from outright rejection to those who believe it to be intuitively obvious, but untestable and therefore unhelpful. In this book, the author introduces an empirically testable and useful theory of psychological hedonism based on contemporary theory and research in the emerging field of affective neuroscience. He goes on to argue that people are genetically endowed with a tendency towards psychological hedonism as a function of Darwinian processes. This view of psychological hedonism in light of its Darwinian origins - thereinafter referred to as Darwinian hedonism - is essential to address the growing global epidemic of unhealthy behavior, such as poor diet, physical inactivity, and substance use.