Multicomponent analyses of a hydatid cyst from an Early Neolithic hunter-fisher-gatherer from Lake Baikal, Siberia

Calcified biological objects are occasionally found at archaeological sites and can be challenging to identify. This paper undertakes the differential diagnosis of what we suggest is an Echinococcus granulosus hydatid cyst from an 8000-year-old mortuary site called Shamanka II in the Lake Baikal region of Siberia. Echinococcus is a parasitic tapeworm that needs two hosts to complete its life cycle: herbivores and humans are intermediate hosts, and carnivores such as dogs, wolves, and foxes are definitive hosts. In the intermediate host the Echinococcus egg hatches in the digestive system, penetrates the intestine, and is carried via the bloodstream to an organ, where it settles and turns into an ovoid calcified structure called a hydatid cyst. For this object, identification was based on macroscopic, radiographic, and stable isotope analysis. High-resolution computed tomography scanning was used to visualize the interior structure of the object, which is morphologically consistent with the E. granulosus species (called cystic Echinococcus). Stable isotope analysis of the extracted mineral and protein components of the object narrowed down the range of species from which it could come. The stable carbon and nitrogen isotope ratios of the object's protein, and stable carbon isotope ratio of the mineral, closely match those of the likely human host. Additionally, the δ13C protein-to-mineral spacing is very low, which fits expectations for a parasitic organism. To our knowledge this is the first isotopic characterization of a hydatid cyst and this method may be useful for future studies. The hydatid cyst most likely came from a probable female adult. Two additional hydatid cysts were found in a young adult female from a contemporaneous mortuary site in the same region, Lokomotiv. This manuscript ends with a brief discussion the importance of domesticated dogs in the disease's occurrence and the health implication of echinococcal infection for these Early Neolithic hunter-fisher-gatherers.