Paleodiet studies using stable carbon isotopes from bone apatite and collagen: examples from Southern Ontario and San Nicolas Island, California

Abstract

Stable carbon isotope studies using the mineral portion of bone have shown that this is a feasible area of research for providing paleodietary data. Stable carbon isotopes in collagen ( δ 13C CO) reflect primarily the protein portion of diet, whereas stable carbon isotopes in carbonate from bone mineral ( δ 13C CA) reflect the whole diet. While spacing between stable carbon isotopes in carbonate and diet is thought to be constant, spacing between stable carbon isotopes in collagen and diet may be variable depending on whether the carbon isotope value of protein equals that of the whole diet. In order to elucidate these patterns skeletal remains of prehistoric human groups utilizing different subsistence strategies, from southern Ontario and San Nicolas Island, Channel Islands, southern California, were analysed for stable carbon isotopes in both bone carbonate and collagen. Southern Ontario provides an example where C 4 plants are consumed in combination with indigenous C 3 plants and C 3-consuming animals; whereas San Nicolas Island provides an example where marine foods are consumed in combination with terrestrial C 3 foods. Results indicate that, in southern Ontario, maize was consumed at an earlier date than is indicated by the analysis of collagen alone, and that, on San Nicolas Island, marine food consumption did not decrease over time as occurred on nearby Channel Islands. The analysis of stable carbon isotopes from bone carbonate provides additional paleodietary information to the analysis of stable isotopes from collagen. Protein-poor foods will be reflected in carbon isotopes in carbonate when consumed in small amounts, whereas they will be reflected in collagen only when consumed in sizeable proportions.