Book excerpt: Natural selection has operated as strongly or more so on the early stages of the lifespan as on adulthood. One evolved feature of human childhood is high levels of behavioral, cognitive, and neural plasticity, permitting children to adapt to a wide range of physical and social environments. Taking an evolutionary perspective on infancy and childhood provides a better understanding of contemporary human development, predicting and understanding adult behavior, and explaining how changes in the early development of our ancestors produced contemporary Homo sapiens.