Quantifying Palaeopathology Using Geometric Morphometrics

Abstract

Palaeopathology is the study of disease and injury in archaeological bone. Traditional methods rely heavily on macroscopic description which can have a high degree of subjectivity and error, as well as limiting the types of research questions possible. Geometric morphometrics are a suite of shape analysis techniques and provide an opportunity to investigate possible relationships between skeletal morphological variation and disease. This thesis aims to demonstrate the potential of applying these methods in palaeopathological research and the results illustrate the benefits of using quantifiable and objective shape analysis methods in palaeopathology. The first half of the thesis discusses the use of geometric morphometrics to investigate skeletal variation to identify possible aetiological factors in the development of Schmorl's nodes and osteoarthritis. There was a strong association found between vertebral morphology and Schmorl's nodes in the lower spine. These findings have great implications for both bioarchaeological interpretation and clinical understanding of the aetiology and pathogenesis of Schmorl's nodes. Joint morphology of the proximal ulna and distal humerus was found to have no identifiable relationship with osteoarthritis, indicating that joint morphology is not a predisposing factor in elbow osteoarthritis, nor does osteoarthritis deform the joints in a systematic manner. A tentative relationship between eburnation and knee joint morphology was identified, although these results need to be verified with future research. If the association can be supported, shape analyses may provide a way for clinicians to monitor the progression of the disease. Geometric morphometrics were also shown to objectively record pathological shape deformation resulting from leprosy and residual rickets. The ability to objectively describe lesions with quantified data will greatly strengthen palaeopathology by decreasing the subjectivity and error inherent in macroscopic based methods. This thesis represents promising groundwork for the incorporation of geometric morphometrics into palaeopathological research.