Author ORCID Identifier

https://orcid.org/0000-0002-0352-3777

Date of Award

Spring 5-2-2025

Document Type

Thesis (Ph.D.)

Department or Program

Ecology, Evolution, Environment and Society

First Advisor

Jeremy DeSilva

Abstract

Bipedal locomotion is central to the human condition, having shaped our evolutionary trajectory since its early emergence in the hominin lineage. Despite its importance, key questions remain about its origins and evolutionary trajectory. While many studies have focused on locomotor-related anatomies, comparatively less attention has been paid to the knee joint – a structure critical to the primate locomotor repertoire. This dissertation aims to clarify the form-function relationship of the knee in extant primates to better infer the locomotor behaviors of Miocene hominoids and Plio-Pleistocene hominins. To address these questions, this research employs a multifaceted analytical approach, integrating linear measurements, three-dimensional shape analysis, modern kinematic data, and virtual musculoskeletal modeling. Chapter One reviews linear measurements of the distal femur within the hominin genus Australopithecus. Chapter Two presents a 3D shape analysis of the distal femur and proximal tibia across modern humans, extant primates, and fossil hominins, linking variation in shape to patterns of knee flexion during gait. Chapter Three extends the shape analysis to the Miocene apes Sivapithecus, Morotopithecus bishopi, and Danuvius guggenmosi, contextualizing their knee functional morphology within that of extant primates. Chapter Four integrates these datasets using virtual musculoskeletal simulations to evaluate a novel model of early hominin gait: the extended-hip-bent-knee (EHBK) hypothesis. Together, these dissertation findings support a mosaic pattern of knee morphology among Miocene fossil hominoids and highlight variability in bipedal gait mechanics among Plio-Pleistocene hominins, including the presence of moderate knee flexion in early hominin locomotion.

Original Citation

CH.1

Miller, C. K., & DeSilva, J. M. (2024). A review of the distal femur in Australopithecus. Evolutionary Anthropology: Issues, News, and Reviews, 33(1), e22012.

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