PhD Dissertations: Brian Stewart Chisholm, 1987

Reconstruction of Prehistoric Diet in British Columbia Using Stable Carbon Isotopic Analysis

Information of prehistoric diet can be extremely useful for understanding human behaviour as it relates to food acquisition. In British Columbia prehistoric diet has been inferred from ethnographic, archaeological and zooarchaeological evidence. However, lack of quantified data makes it difficult to determine the degree to which people relied on marine species for their protein, or to compare people from different sites and time periods.

This study uses a new approach, the application of stable carbon isotope analysis of human bone collagen, to obtain such quantified data. Following investigation of the applicability and variability of the analytical technique, ethnographic and archaeological evidence was used to identify dietary species representing marine and terrestrial alternatives. Samples of those species were taken for each of a number of different locales and environments, and representative isotope ratios determined for both marine- and terrestrial-based diets. Isotope ratios for prehistoric humans were then compared to those for the two alternative diets in order to determine the human's degree of reliance on marine species as a protein source.

Results indicate that prehistoric British Columbian coastal dwellers obtained about 90 ± 10% of their protein from marine species, specifically salmon. People in areas away from major salmon streams obtained some of their protein from marine species although the amount was much less. These proportion do not appear to have changed significantly for the last 5000 years. However, some differences have been observed in results, between females and males, adults and children, and geographic areas.