Doctoral Dissertation Research: Behavioral reconstruction and the effects of habitual activity on the bone-muscle interface

George Washington University, Washington DC

Investigators

Abstract

The skeleton can provide many clues about movement and behavior patterns, and this form-function relationship makes bone an important source of data for reconstructing the evolutionary history and past behaviors of animals and humans. In this dissertation project, the response of bone to habitual activity will be investigated in murine and primate models to improve our understanding of entheses (muscle attachment sites on bone), because the relationship of this particular feature of bone to function is not fully understood. Experimental evidence of enthesis change due to activity will be applicable across a variety of disciplines, including paleoanthropology, biology, clinical medicine and forensic science. All images generated as a result of this work will be made available to other researchers in order to promote further interdisciplinary research. The project will support student research experiences, including for students from groups underrepresented in STEM research, and both traditional and online public science outreach activities. The use of entheses to reconstruct species-level locomotor patterns and individual occupation relies on the premise that bone responds to mechanical loading with remodeling and the accumulation of new bone. However, recent experimental studies have questioned the assumed effect of muscle activity on bone and demonstrated no relationship between exercise and measures of the entheseal surface. This project addresses the methodological issues concerning attachment site biology, taking a multilevel approach to assess if and how entheses can be used for behavioral reconstruction. The first component of this study utilizes a murine model with controlled and elevated running and climbing regimes to test whether increased activity results in corresponding increases to muscle force-generating capacity, bone surface roughness, bone depositional rate, and/or bone cross-sectional geometric properties. The results of this aim will then be applied to an existing sample of primate skeletons in order to observe how different locomotor modes relate to enthesis development. A selection of locomotor-relevant entheses in suspensory, quadrupedal and bipedal primates will be examined with surface and CT scans for patterns of attachment site characteristics by activity. A combined analysis of the macroscopic bone surface and its underlying mechanical environment will provide a comprehensive view of the enthesis region. These data will provide an empirical foundation for the interpretation of enthesis morphology, with the long-term goal of enabling non-destructive behavioral reconstruction on fossil primates using these structures.