Chronology of middle Holocene hunter-gatherers in the Cis-Baikal region of Siberia: Corrections based on examination of the freshwater reservoir effect

A dataset of 256 AMS radiocarbon dates on human skeletal remains from middle Holocene cemeteries in the Cis-Baikal region, Siberia, and associated carbon and nitrogen stable isotope values are analyzed for new insights about culture history and processes of culture change. First, based on the typological criteria all dated human burials are assigned to mortuary traditions and typochronological units-Late Mesolithic, Early Neolithic, Late Neolithic and Early Bronze Age. Next, all dates are corrected for the Freshwater Reservoir Effect (FRE) according to the regression equations developed using paired radiocarbon dates on human and terrestrial faunal remains from the same graves and examined for chronological trends using a Bayesian approach. While the entire corrected culture historical sequence is younger by roughly 200-400 years relative to the previous model the shift of the specific period boundaries is not systematic due to the varying proportion of aquatic food in the diets of the relevant groups. Examination of the dataset subdivided into smaller spatio-temporal units provides additional insights. During the Early Neolithic, in the Angara and Southwest Baikal micro-regions there is a chronological trend toward increased reliance on aquatic food. During the Early Bronze Age in the Little Sea micro-region, there appears to be a trend toward increased reliance on the Baikal seal. This shift, however, can also be interpreted as increasing migration over time of new groups from the Upper Lena. The sample from the Early Neolithic Shamanka II cemetery in Southwest Baikal shows two non-abutting phases of use each displaying a trend toward greater consumption of aquatic foods. These findings provide new chronological framework for the study of other cultural changes affecting middle Holocene hunter-gatherers in the region. The results may also allow better correlation with other sequences, cultural and environmental, that are not affected by the FRE.