Evolutionary theorists have linked humans' long periods of childhood dependency and post-reproductive life to brain development, learning, and distinctively human social structures. However, the patterns in life history variation and paleoanthropological evidence challenge these arguments. How can scholars identify and explain the peculiar features of human life history, such as the rate and timing of processes affecting survival and reproduction? When and why did uniquely human patterns evolve? This volume brings together specialists in the behavioral ecology and demography of hunter-gatherers; human growth, development, and nutrition; paleodemography; human paleontology; primatology; and the genomics of aging to address these questions. In attempting to specify the life history features that distinguish humans from our closest primate relatives, they review alternative explanations and consider multiple lines of evidence for testing them. This volume sets the agenda for future research on this topic.