Hindlimb cortical bone adaptation and locomotion in primates

University Of Southern California, Los Angeles CA

Investigators

Abstract

This project will examine the strength of leg and foot bones in primates and other mammals in relation to locomotor behaviors. The investigators use high-resolution three-dimensional imaging to quantify internal features of long bones of the hindlimb in a broad sample of living and fossil primates, rodents, and marsupials. Results will contribute new information on how bone responds to forces produced during locomotion, how early primates adapted to arboreal environments, and how the postcranial skeleton evolves in response to similar locomotor regimes in different mammalian groups. The societal impacts of this research include broadening participation of underrepresented groups in science and improving STEM education through integrating research and education. An outcome of this project will be training students traditionally underrepresented in STEM and preparing educational materials to be shared through public outreach events and an online data repository. Leaping is an important behavior for many living primates and is thought to have been vital to the origin of the primate body plan. While it is generally accepted that the earliest primates used some form of leaping locomotion, how and when the primate skeleton adapted to leaping behaviors is not well understood. This research compares species that differ in locomotor behavior to 1) identify form-function links between hindlimb internal bone anatomy and prevalence of leaping behaviors, 2) determine whether leaping primates, rodents, and marsupials share similar hindlimb bone strength adaptations due to their similar ways of moving, and 3) analyze how these measures of hindlimb bone strength evolved in living and extinct primate groups. Using high-resolution micro-computed tomography, cross-sectional geometric properties representing measures of bone strength will be calculated for the calcaneus, navicular, femur and tibia, and compared across species that differ in the amount of time spent leaping versus using quadrupedal behaviors. In addition, phylogenetic comparative methods will be used to evaluate macroevolutionary patterns, adaptive shifts, and convergent evolution of leaping behaviors in a sample of extant and fossil Eocene primates. 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.