This volume highlights current research in the field of animal behavior, with an emphasis on evolutionary perspectives. The contributors represent paleontological, field, and experimental approaches. They focus on a series of studies that confront wide-ranging issues, including sexual selection, mate choice, differential parental investment, apparent altruism, cooperative behavior, and the relevance of phylogenetic constraints and historical information. The volume will be of special interest to evolutionary biologists, behavioral ecologists, and paleontologists.