Thesis Defences

Degree of Doctor of Philosophy

Laure Spake

Using anthropometrics and dental formation stages of contemporary children to investigate the impact of biological mortality bias on interpretations of past population health

Friday, 22 May 2020 at 9:00am
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Biological mortality bias is the concept that within a population, the individuals who die (non-survivors) are biologically different from their surviving peers. Because nonsurvivors may have experienced more health insults during their lives than survivors, they may differ from survivors in their biological phenotypes. Thus, if biological mortality bias exists and is substantial in magnitude, interpretations of past population health made from skeletal samples (non-survivors) may not accurately reflect the health of the surviving population.

This dissertation explores biological mortality bias as reflected in the growth of juvenile individuals aged birth to 12 years. Growth is known to be susceptible to environmental influences, and thus has been widely used by bioarchaeologists as a marker of general population health. However, the sensitivity of growth to environmental effects also makes it likely to be affected by biological mortality bias.

The dissertation is composed of four separate scientific papers aimed at examining the effects of biological mortality bias from multiple perspectives. The first paper is a preliminary study contrasting: 1) body length between survivors and non-survivors in a sample of contemporary children; and 2) height and weight between survivors and nonsurvivors in a diseased sample of girls admitted to a historical tuberculosis sanatorium. The following three papers draw data from a sample of full body post-mortem computed tomography (CT) scans of contemporary children. More specifically, the second paper contrasts dental development between survivors and non-survivors using transition analysis. The third paper presents a protocol for anthropological measurement of long bones in CT scans and reports on its accuracy and replicability. The fourth paper makes use of this protocol for data collection to compare long bone length for age between survivors and non-survivors.

Evidence for biological mortality bias is found in linear growth as measured both by full body anthropometrics and long bone lengths, but not in dental development as measured by dental formation stages. These findings reinforce confidence in dental age estimates, but suggest that mortality bias may complicate bioarchaeological analysis of juvenile skeletal remains.

Keywords:  The Osteological Paradox; growth; long bones; dental development; anthropometrics; survivorship

Degree of Master of Arts

Brock Wiederick

Friday, 22 May 2020 at 10:30am
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Archaeological Site Distribution and the Formation of Early Polities in Eastern Tigrai (Agame), Ethiopia  


Archaeological site formation and distribution in Eastern Tigrai, Ethiopia can reveal the characteristics behind the formation of the earliest polities in the Northern Horn of Africa during the past three millennia. Within a landscape archaeology framework, site attributes, landscape attributes, diagnostic artefacts, chi-square analysis, and settlement patterning can be synthesized to understand the socio-political and economic conditions present within the study area, specifically, and Eastern Tigrai, generally, between the Pre-Aksumite (>700 BCE) and Post-Aksumite (<700CE) periods. The unique characteristics present within the archaeological record in Eastern Tigrai during the Pre-Aksumite, Aksumite, Post-Aksumite, and Ethnographic periods indicates that an atypical heterarchical political organization is present within Eastern Tigrai. This atypical political trajectory combined with recent research raises questions about the exact relationship between Eastern Tigrai and the rest of the Aksumite Empire during its influence in the region.

Keywords:  Ethiopia; Settlement; Landscape; Aksumite; Pre-Aksumite; Survey.