Carbon isotope analysis of separate chemical phases in modern and fossil bone

Abstract

Studies evaluating the distribution of stable carbon isotopes in bone and other tissues of both human and non-human animals have recently been reported^1–6. Those investigations which examined the isotopic composition of bone have concentrated on the analysis of bone collagen and demonstrated that the ¹³C/¹²C ratios in bone collagen are directly related to the ¹³C/¹²C ratios of primary photosynthesizing plants in the diets of the animals concerned^6–8. With regard to archaeological applications, such analyses have been limited to relatively young samples because of the instability of collagen in bone. We have extended the isotopic method of dietary analysis by using both the organic and inorganic phases of bone with equally good results. In the case of material over a few thousand years old, unless special conditions have preserved collagen, analysis of the organic phase of bone is no longer practical due to its deterioration⁹. The technique reported here allows dietary analysis of bone over 10,000 years old by using the inorganic phase, which is more stable in fossil material.