This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Studies of maternal investment strategies in primates have focused mainly on the behavior of lactating females and their infants, documenting the frequency of suckling, proximity maintenance, and the dynamics of weaning. To date little is known about the primary form of maternal investment; milk synthesis. This project will address two important questions: (1) How do maternal condition and life history tradeoffs affect lactational investment and subsequent reproduction and (2) How do differences in lactational investment influence infant developmental trajectories? Longitudinal comparisons of lactation performance within and among mothers, and the consequences for infant growth and behavioral development, will demonstrate how mothers manipulate investment in relation to their own, and their infant's, physiological and social condition. This research project will provide the first systematic, longitudinal information investigating all dimensions of mammalian lactation strategies within a single species (milk synthesis, nursing behavior, duration of lactation until weaning, and number and sex-ratio of infants supported during lactation). As such this study will explore fundamental aspects of lactation that have previously not been investigated, and advance our understanding of how selection has shaped maternal investment strategies in a species characterized by a slow life history and complex social organization. Moreover the broader impacts of this research are substantial. The data from this study will directly address critical issues affecting the health of human mothers and their infants. Breastfeeding rates in the US and throughout the world are significantly below optimum, contributing to long-term deleterious developmental and health consequences for infants. Advances in understanding how constraints during lactation influence the nutritional value of the mother's milk and the consequences for infants, under controlled research conditions, will provide insights into similar challenges for human mothers. This research will provide valuable resources, in the form of archived milk samples and public databases, for other researchers studying infant development from ultimate and proximate perspectives. Lastly, the proposed study will incorporate training programs at UC Davis and the California National Primate Research Center. The award will provide partial post-doctoral level support for a young female new investigator as well as employ one full-time technician, one half-time technician, and one undergraduate.
