How do we make decisions? Conventional decision theory tells us only which behavioral choices we ought to make if we follow certain axioms. In real life, however, our choices are governed by cognitive mechanisms shaped over evolutionary time through the process of natural selection. Evolution has created strong biases in how and when we process information, and it is these evolved cognitive building blocks--from signal detection and memory to individual and social learning--that provide the foundation for our choices. An evolutionary perspective thus sheds necessary light on the nature of how we and other animals make decisions. This volume--with contributors from a broad range of disciplines, including evolutionary biology, psychology, economics, anthropology, neuroscience, and computer science--offers a multidisciplinary examination of what evolution can tell us about our and other animals' mechanisms of decision making. Human children, for example, differ from chimpanzees in their tendency to over-imitate others and copy obviously useless actions; this divergence from our primate relatives sets up imitation as one of the important mechanisms underlying human decision making. The volume also considers why and when decision mechanisms are robust, why they vary across individuals and situations, and how social life affects our decisions.