An attempt to define the field of evolutionary developmental psychology - the application of the principle of natural selection to explain contemporary human development. The authors point out that an evolutionary-developmental perspective allows one to view gene-environment interactions, the significance of individual differences, and the role of behaviour and development in evolution in much greater depth. The authors also focus on how an evolutionary perspective can foster a better understanding of human development and how developmental processes may have influenced the course of human evolution. There are chapters that explore factors influencing parenting and other aspects of family life; the role of play; and the interacting roles of an extended juvenile period, a big brain, and a complex social structure in human cognitive evolution. The authors present a hybrid approach to evolution and development, pointing out that though underlying assumptions held by evolutionary and developmental psychologists have been at odds, each field has much to offer the other.