An exciting new cross-disciplinary field of biocultural research is emerging at the start of the twenty-first century: developmental evolutionary biology. Looking at the behaviorial ontogeny of primates, the authors–leading scholars of biological anthropology, evolutionary biology, developmental psychology, and cognitive neuroscience–pose questions that probe our fundamental understanding of the human species. The authors postulate answers that will change the way we look at how cognition, language, and behavior develop in primates.