Health and settlement implications of parasites from Pacific Northwest coast archaeological sites (British Columbia)

Rhonda R. Bathurst
Dept. of Anthropology, McMaster University
July, 2005
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The aim of this project was to recover archaeological evidence of human parasite infection from the coastal shell middens of British Columbia, Canada. Although the preservation and recovery of intestinal parasites are not new to ancient disease studies, as yet there has been a paucity of investigation for such forms of evidence at temperate, coastal archaeological sites such as those found on the central coast. The reasons for this are threefold, and address some of the long-held assumptions about ancient subsistence economies, diseases in the Americas, and the degree of preservation in shell midden features. Parasites are often considered a disease of urban societies. Classified on the basis of their subsistence economy, the archaeological populations of the Northwest Coast were non-agrarian hunter-fisher-gatherers. Normative thinking about hunters and gatherers maintain that such cultures were benignly impacted by infectious disease agents. As the level of disease risk is considered low, there has been little expectation of finding pathogen evidence at hunter-gatherer sites. But consistent and quantifiable microscopic evidence of intestinal parasites, some as much as six thousand years old, was successfully recovered from 11 of 15 shell midden sites tested. Auger samples produced preserved eggs of four parasite taxa, including giant human roundworm (Ascaris lumbricoides ) and broad fish tapeworm (Diphyllobothrium spp.), genera relevant to human health. The ecological, epidemiological and cultural significance of these finds are discussed in relation to health, settlement, behaviour patterns and regional culture history. Methodologically, this project demonstrates a replicable and noninvasive process for retrieving parasite evidence from midden sediments. The results of this study contribute to what is known about hunter-gatherer health, broadening the range of parasite species known in the Americas and confirming the antiquity of the human- parasite relationship.