First Advisor

Marian Hamilton

Degree Name

Bachelor of Science

Document Type


Date Created



Obligate bipedal locomotion, mandatorily walking on two legs, is vastly important as it is the fundamental precursor to the human lineage; it precedes tool usage and language. Chimpanzees, our closest living ancestors for the human ancestral condition, are often the proxy and are the dominant subject of human bipedalism studies. There are additional species, such as arboreal Black Spider Monkeys (Ateles paniscus) who habitually travel through the trees bipedally. These facultative bipedal primates (FBP) introduce a new lens to how modern human talus and calcaneus’ mobility has adapted to environmental shifts such as the transition from arboreal to terrestrial habitation. Studying ankle and heel morphology across multiple species with varying levels of bipedalism allows for the opportunity to better understand how lower limb mobility and stability differ as primates become more terrestrial. I provide quantitative and comparative analyses of tarsal morphology in Homo habilis along with various FBPs: chimpanzee (Pan troglodyte), Black Spider Monkey (Ateles paniscus) and Western Gorilla (gorilla gorilla), as well as obligate bipedal primates (Homo sapiens sapiens) by using a visual quantitative method known as geometric morphometrics (GM). GM is a standard in the field of comparative functional anatomy and paleoanthropology. We found that the morphology of the ankle joint will be more similar between early hominins and modern humans than that of FBP. This research continues to improve our understanding of how paleoenvironmental changes in the past 3 million years might have influenced the evolution of bipedalism in primates, particularly in hominins and more recently, humans.

Abstract Format



Biological and Physical Anthropology


functional morphology; facultative bipedal primates; bipedalism; geometric morphometrics; GM


28 pages

Rights Statement

Copyright is held by the author.