Paleosyndemics: A Bioarchaeological and Biosocial Approach to Study Infectious Diseases in the Past

Skeletons drawn from archaeological contexts provide a fund of data for assessing disease in general and timing of epidemics in particular in past societies. The bioarchaeological record presents an especially important perspective on timing of some of the world's most catastrophic diseases, such as leprosy, tuberculosis, plague (Black Death), and treponematosis. Application of new developments in paleogenomics and paleogenetics presents new opportunities to document ancient pathogens' DNA (for example, Black Death), track their history, and assess their beginning and end points. Paleopathological documentation of disease terminus is complex, in part owing to circumstances where past communities experienced overlapping epidemics, such as leprosy and plague. For most settings, these syndemics-whereby there is an interaction between two or more epidemic diseases-both exacerbate and enhance the burden of morbidity in a community or region. Fundamental to understanding the severity and duration of epidemics is the consideration of multiple factors that simultaneously influence the severity and duration of the specific infectious diseases in a community or region, including poor oral health, under-nutrition, iron deficiency anemia, and elevated parasite load. In our view, comprehending the beginning, the middle, and the end of epidemics requires understanding the wider context of syndemics, the multiple challenging circumstances that undermine health and community stability, and how biosocial factors differentially affect the immune competence of individuals. This article provides several examples of the application of bioarchaeology and syndemics theory in achieving an understanding of how epidemics end. Pathogens continue to circulate, even after what appears to be the end. In effect, then, there is no "end," just evolution of opportunistic pathogens and our ability (or not) to mitigate them.