Uncovering Hidden Frailty and Disease Risk in Archaeological Populations Via Anicent Oral Microbiome Analysis

Noncommunicable diseases exact devastating physical, social, and economic tolls on communities around the world. Despite the significant impacts of these diseases, little is known about their evolutionary histories or how historical transitions in human lifestyles, environments, and diets have impacted their epidemiological attributes. Tracing the history of these diseases over time has the potential to provide critical insights into prevailing modern health inequalities and may even help in the development of ameliorative strategies for preventing and managing these conditions. However, progress on this front has been limited because, unlike many infectious conditions, noncommunicable conditions are conventionally untraceable in the archaeological record. That is, the vast majority of noncommunicable diseases lack either distinctive pathological agents that could be recovered via ancient DNA analysis or specific diagnostic skeletal lesions observable to biological anthropologists. As such, a different approach is required for studying their evolutionary histories. Based on modern medical evidence linking oral health and noncommunicable diseases, as well as on paleoepidemiological studies associating oral health with elevated morbidity and mortality risk, this dissertation explores the utility of the oral microbiome as an indicator of noncommunicable diseases. The oral microbiome, the collection of microorganisms inhabiting the oral cavity, is intricately linked with both oral and systemic health and is known to be associated with several types of noncommunicable disease. Moreover, the oral microbiome exhibits remarkable preservation in archaeological contexts and can be reconstructed via ancient DNA methods from dental calculus. By showing that the oral microbiome of ancient populations is associated with inflammation-related skeletal characteristics and by exploring the microbial taxa and functions associated with disparate morbidity and mortality traits, this work demonstrates the feasibility of using the ancient oral microbiome as an indicator of hidden noncommunicable disease-associated frailty in past populations.