Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Arts

Program

Anthropology

Supervisor

Nelson, Andrew J.

Abstract

Anthropologists employ biodistance analysis to understand past population interactions and relatedness. The objectives of this thesis are twofold: to determine whether a sample of five mummies from the pilgrimage centre, Pachacamac, on the Central Coast of Peru comprised local or non-local individuals through an analysis of cranial nonmetric traits using comparative samples from the North and Central Coasts of Peru and Chile; and to test the utility of machine-learning-based image segmentation in the image analysis software, Dragonfly, to automatically segment CT scans of the mummies such that the cranial nonmetric traits are visible. Results show that while fully automated segmentation was not achieved, a semi-automated procedure was adequate for visualizing and scoring the skulls and saved time over manual segmentation methods. The sample from Pachacamac was too small to make significant inter-site comparisons, but a broader regional analysis suggests there are significant biological differences between geographical regions along the coast.

Summary for Lay Audience

This thesis focuses on a sample of five mummies from the Pachacamac sanctuary on the Central Coast of Peru. Pachacamac served as a ceremonial centre to which many groups of people travelled to engage in various forms of ritual behavior, indicating that it was a significant cosmopolitan centre throughout multiple Andean cultural phases from the Early Intermediate Period (200 BCE-AD 600) to the Spanish Conquest (AD 1532). The two central objectives of this study are anthropological and methodological. The anthropological objective is to conduct a biodistance analysis of cranial nonmetric traits to assess the dissimilarity between samples from the North and Central Coasts of Peru and the coast of Chile to determine whether the sample from Pachacamac represents the local population or pilgrims drawn from a wide area. Biodistance studies can reveal both genetic and environmental differences between populations by measuring divergence based on polygenic traits.

Because the skulls are inside mummy bundles, or fardos, Computed Tomographic (CT) scans of the mummies were studied using the image analysis software, Dragonfly. The methodological objective of this study is to test the utility of the machine-learning-based image segmentation tools in Dragonfly to automatically segment CT scans of the mummies such that the skulls can be scored for these traits. Image segmentation is the process of separating the components of images into meaningful segments for analysis. Currently, researchers rely on manual segmentation of CT images, a process that is tedious and difficult to replicate.

The findings show that while fully automated segmentation was not achieved, a semi-automated procedure proved adequate for visualization and scoring of the skulls and saved time over manual segmentation methods. The sample from Pachacamac was too small to make significant inter-site comparisons, but a broader regional analysis suggests there are significant biological differences between geographical regions along the coast. Previous studies of cranial nonmetric traits have focused on dry bone. This project is the first to examine these traits on mummified individuals using CT and demonstrates the benefits of investigating more complex methodologies in paleoimaging.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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