Doctoral Dissertation Research: The energetic costs of motherhood in primates

Mammalian mothers have evolved to produce milk for their infants while maintaining a healthy body condition, but little is known about how wild primate mothers modify their diet and behavior to ensure both infant and mother survival. This dissertation project examines how wild orangutan mothers meet their energetic needs while nursing an infant during extended periods of low fruit and overall caloric availability. The research will provide a comparative model for human ancestors that may also have survived and reproduced through periods of resource uncertainty. In addition, Bornean orangutans are critically endangered, and research findings from this project will support primate conservation efforts. This project will also provide training in data management, behavioral data collection, and lab-based behavioral endocrinology for students from underrepresented groups in the STEM fields. Research focusing on primate reproduction and life-history has revealed that primates have longer gestation and lactation periods, and extended periods of juvenile dependency relative to other mammalian species of similar size. Thus, it is likely that primate mothers, particularly those who nurse for multiple years spanning periods of unpredictable and low food availability, will have evolved a suite of behavioral and physiological adaptions to cope with the long-term energetic demands of motherhood while minimizing risk to her developing infant. This project examines the behavioral and physiological strategies that wild Bornean mother orangutans (Pongo pygmaeus wurmbii) use to maintain homeostasis across periods of infant development. The project utilizes several non-invasive methodologies: behavioral observations of orangutans, macronutrient analysis of food items, and physiological urinary analyses. This will be one of the first studies of a wild primate species to test if mothers modulate their nutritional intake and subsequent energetic status throughout lactation and infant development, and if/how they maintain homeostasis during this energetically costly period.