Musculoskeletal modeling and simulation of hominin bipedal locomotion

Ragni, Anna, Washington DC

Investigators

Abstract

This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. Under the sponsorship of Dr. Ashley Heers at California State University, Los Angeles, this postdoctoral fellowship award supports an early career scientist creating a computer simulation of how human ancestors may have walked. While walking on two feet may seem mundane, this remarkable ability predates other uniquely human qualities, including a large brain, and separates us and our fossil lineage from other primates. All fossil human ancestors show some indication of walking on two feet, but several species, like 3.2 million-year-old Australopithecus afarensis, may have walked more like an upright chimpanzee than a modern human, or in a unique way all together. Biomechanical modeling and simulation are quantitatively rigorous methods that have the unique ability to address this type of uncertainty. Modeling and simulation allow researchers to create realistic three-dimensional musculoskeletal models whose anatomical parameters can be individually manipulated to explicitly examine form-function relationships. By creating a musculoskeletal model of A. afarensis and bracketing parameters with data on humans and chimpanzees, this project will explore the hypotheses that A. afarensis was capable of chimp-like, human-like, or uniquely in-between bipedal walking, in conjunction with positive, stabilizing, or negative selection. Musculoskeletal modeling and simulation have previously been used to assess certain aspects of hominin locomotion, but a phylogenetically bracketed model based on the most up-to-date reconstructions has not yet been created or tested in a paleoanthropological context. This project will improve our understanding of locomotor potential in “mosaic”, “proto”, or “transitional” taxa during human evolution, and can inform evolutionary scenarios that will impact not only paleoanthropology, but also evolutionary biology. This project will also introduce data for future hypothesis testing, allowing researchers to explore how the locomotion of A. afarensis might have related to paleobiological variables like environment, diet, and social behavior. 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.