Doctoral Dissertation Research: Assessing weight-gain tendencies in a non-human primates

White adipose tissue (WAT) is involved in energy (fat) storage and related metabolic disorders (e.g., obesity). The high level of WAT in humans, as compared to other primates, is interpreted as an adaptation to the assumed frequent dietary scarcity faced by our hominin ancestors. This concept is central to the idea that human bodies are adapted to face scarcity, and thus that humans are evolutionary predisposed to store energy in the form of fat (the thrifty-genotype and thrifty-phenotype hypotheses). The current obesity epidemic, according to this idea, results from a mismatch between a past environment of scarcity and the contemporary dietary abundance that is found in many places around the globe. If this idea is correct, the obese-tendency trait should be found in humans but not in other primates. However, very few data exist to indicate whether or not other non-human primates present this characteristic. If this trait is present in other non-human primates, it would suggest that a high WAT level is an ancient evolutionary trait and not a recent adaptation to scarcity. This doctoral dissertation project addresses this question by investigating how dietary changes affect body composition in humans and baboons. The study includes a variety of outreach activities, and collaborations with the Great Ape Heart project, which is constituted by a group of experts that aid in understanding and treating cardiac disease in great ape species. To assess whether the obesity-prone tendency of humans is a trait shared with other primates, the researchers: (1) examine how dietary composition correlates with dietary biomarkers in humans; (2) assess body composition and bone mineral density in baboons (Papio anubis) that ate a low fiber but high fat and sugar diet, and (3) compare adipose deposits and lean body mass between species using DiceCT scans. The study informs about the variation in the plasticity of body composition across primate species, providing insights into the evolutionary history of human and non-human primate adiposity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.