Stable isotope analysis of serial samples of third molars as insight into inter- and intra-individual variation in ancient diet

Identification and analysis of faunal and botanical remains provide important insight into paleodiet, but tend to average dietary behaviors over many individuals and large windows of time. Stable isotope analyses of human bone collagen and apatite, while less specific regarding diet, nicely complement faunal and macrobotanical analyses by giving glimpses into the diets of individuals, but still time-average diet over large windows (ca. 5-20 years). Recent advances in micro-sectioning of teeth provide the opportunity to examine intra-individual changes in diet over small windows of time, as small as 1 year or less. We use stable isotope data from human third molar dentin as a window into examining intra-individual variation in diet at a hunter-gatherer archeological site in Central California (CA-SOL-11). Data show significant dietary variation between individuals, suggesting there were many ways that individuals met basic dietary needs at the site. Data also show that some individuals significantly altered their diet in the course of their lives, with pulses of high brackish-water exploitation lasting between 1 and 4 years. We suggest one of three scenarios to explain these fluctuations: that brackish water foods served as fallback resources, that some individuals shifted their place of residence, or that changing trade relations may have caused fluctuations in consumption of brackish-water foods.