Stable isotope indicators of provenance and demographics in 18th and 19th century North Americans

Abstract

Using stable isotopes to gain insight into individual life histories is a valuable tool for unidentified or incomplete remains lacking historic records. This study analyzed stable carbon, nitrogen, and oxygen isotopes from bones and teeth of 18th–19th century North Americans of known ancestry, social class, and region of origin in an effort to discern qualitative patterns and create a quantitative predictive model of demographic information. The δ13Ccollagen, δ13Cstructural carbonate, and δ18Ostructural carbonate values provide the most overall information for detecting demographic differences, with δ15Ncollagen and δ18Ophosphate to a lesser degree. Region of origin was the most predictable demographic factor with 82% correct classifications based on a two-variable model using δ13Ccollagen and δ18Ometeoric water calculated from δ18Ostructural carbonate, which reflects the influence of dominant local vegetation types and local drinking water. Ancestry was correctly identified in 68% of cases using δ13Ccollagen. Social class was less predictable with correct identification in 60% of cases based on δ13C, δ15N, and δ18O values where the upper class was most distinguishable. Isotope patterns observed in ancestry and social class groups are linked to cultural food preferences and food availability. Certain sample sites, such as military burials and urban cemeteries, show a greater range of isotope values suggesting a variety of individual regional origins and cultural backgrounds. Burials of extreme upper or lower class individuals show greater isotopic homogeneity suggesting reliance on localized food sources or cultural preferences for particular dietary choices.