Breastfeeding is a biocultural phenomenon: not only is it a biological process, but it is also a culturally determined behavior. As such, it has important implications for understanding the past, present, and future condition of our species. In general, scholars have emphasized either the biological or the cultural aspects of breastfeeding, but not both. As biological anthropologists the editors of this volume feel that an evolutionary approach combining both aspects is essential. One of the goals of their book is to incorporate data from diverse fields to present a more holistic view of breastfeeding, through the inclusion of research from a number of different disciplines, including biological and social/cultural anthropology, nutrition, and medicine. The resulting book, presenting the complexity of the issues surrounding very basic decisions about infant nutrition, will fill a void in the existing literature on breastfeeding.