Doctoral Dissertation Research: How primates assess risk while moving in the trees

Most primate species live and move in trees, and there is a wealth of research on how the shape of primate skeletons and the way they move allows primates to navigate branches that can be steep, thin, spread out, and bend underneath their weight. This doctoral dissertation research project assesses how primate cognition may allow these animals to stay safe while navigating potential risks in their environment. The first part of this research analyzes video footage of primates moving in their wild habitats to assess whether they change way they move when crossing gaps or when moving at different heights in trees. The second part of this research studies how day-living and night-living primates collect information about the safety of potential supports for movement when different amounts of light are available. The results of this research help us better understand how anatomy and decision making help our close relatives navigate their environments. This project supports K-12 STEM education and public outreach through short courses and internships for high school students. Arboreal locomotion is particularly difficult, given that supports are discontinuous and vary in size, orientation, and compliance. Most previous studies on primate locomotor adaptation have adopted a framework that directly connects variation in postcranial morphology with locomotor performance to assess whether primates are uniquely suited to this challenging environment. However, previous work has largely bypassed the sensory and cognitive processes that may also influence behavior. This project uses analytical tools novel to the field of primate locomotor biomechanics to investigate how primates assess risk in arboreal environments, focusing on three integrated projects to analyze recordings of primates moving in their environments, designed to 1) assess baseline performance of primates in simulated arboreal environments, performance under varying light conditions, and how these variables influence path choice, and 2) quantifying behavioral profiles of several different nonhuman primate species as they make decisions on how to move on varied supports in their wild habitats. The results of this research contribute to a better understanding of primate adaptation and evolution, and specifically inform ideas regarding the sensory and cognitive processes that go into maintaining safety while moving in the trees. 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.