Stable Carbon and Nitrogen Isotope Analysis of Human Diet Change in Prehistoric and Historic Poland

This dissertation uses a well-established tool in anthropology – stable carbon and nitrogen isotope analyses of human bones – to reconstruct past human diet in Poland. Bone collagen and carbonate of 32 animals and 167 human skeletons from North-Central Poland are studied. The sites studied are from Rogowo (2nd c. AD), Kałdus (11th-13 th c.) and Gruczno (12th-14th c.)., all inland sites near the Vistula River, along with four isolated skeletons from the Neolithic and the Iron Age. With this sample I investigate two primary predictions: 1) stable isotope ratios increase through time, reflecting an increase in consumption of marine fish concomitant with religious and economic change, and 2) stable isotope signatures from medieval samples are more heterogeneous than those from pre-medieval samples and are related to status (as estimated by grave goods) and sex. Collagen was extracted by demineralizing cleaned, ground bone particles in hydrochloric acid, followed by a soak in sodium hydroxide to separate humic contaminants and lipids. Carbonate was purified from bone by soaking cleaned, powdered bone in bleach to remove the organic components, and then in acetic acid to remove diagenetic carbonates. Diagenesis of bone mineral was assessed through Fourier transform infrared spectroscopy. Stable isotope analyses were conducted at the Stable Isotope Biogeochemistry Laboratory in the School of Earth Sciences, The Ohio State University. Stable nitrogen isotope ratios of animals are higher than those usually reported for Europe, revealing a different isotopic baseline for North-Central Poland that may result from land management strategies such as manuring and/or burning fields. Human samples show evidence for millet consumption, a uniquely Slavic cultigen in Europe that may be useful in studying Slavic migrations. During the Roman Era, diet was terrestrial-based and included millet and some fish. At the onset of the medieval period, more fish were eaten and diet was highly variable. Contrary to expectations, throughout the medieval period diet became less isotopically varied. Diet at Kałdus was more varied than diet at Gruczno, which likely reflects the different economic functions of the two sites. There are no consistent relationships between burial style and diet, suggesting that differences in diet may not have been drawn on the lines of religion or status. Sex-based differences in stable isotope ratios are observed only in the Roman Era and the latest medieval period, Gruczno site 2, which most closely represents a “true” medieval village. The study samples were intended to isolate temporal diet change and control for regional and between-site variations. However, even in this restricted geographic area, assessing temporal change in diet is not straightforward. Medieval settlements are socioeconomically diverse, complicating simple interpretations of diet change through time. Rather than agreeing with expected, broad trends, diet in this study area was related to local socioeconomic and political circumstances. Local conditions shaping diet in the study area include the shaky foothold of Christianity after state-wide conversion, the Teutonic Order’s influence starting in the 13th c., and the waxing and waning of the medieval sites’ economic importance, independent of trends in Europe at large.