Bone chemistry and palaeodiet: Bioarchaeoiogical research at Roonka Flat, lower Murray River, South Australia 1983–1999.

Abstract

The predominance of stone and bone in prehistoric archaeological deposits has resulted in the development of a range of methods to extract information from these important cultural resources. Since the development of radiocarbon dating in the late 1940s, a variety of analytical techniques derived from chemistry have been applied to archaeological research problems. Many of these methods have been employed in the analysis of archaeological skeletal remains, both human and faunal. In addition to providing information about chronology, chemical analyses of bones and teeth offer independent scientific methods to address past diet, climate and ecology that supplement conventional approaches (Price 1989; Schoeninger and Moore 1992; MacFadden and Bryant 1994; Pate 1994, 1997a; Bocherens et al. 1999). During the 1970s and early 1980s a variety of analytical techniques derived from chemistry emerged in the archaeological literature as a means to reconstruct past dietary patterns. The inorganic and organic chemical constituents of bone provide a record of long-term dietary intake. Elements and amino acids liberated by the digestion of foods are incorporated into the inorganic hydroxyapatite, organic collagen, and non-collagenous protein components of bone throughout a vertebrate's lifetime. In contrast, the chemical composition of teeth reflect the early stages of life during dental development. In some cases, chemical concentrations in bones and teeth can be related quantitatively to the chemical composition of past diet. Thus, chemical analyses of archaeological teeth and bones have the potential to provide information about juvenile and long-term dietary patterns, respectively, in both humans and associated fauna. Elemental analyses of inorganic hydroxyapatite focused primarily on strontium (Sr), barium (Ba) and magnesium (Mg). The concentrations of these alkaline earth metals in bone and tooth mineral reflect percentages of meat vs. plant foods and marine vs. terrestrial foods in the diet (Boaz and Hampel 1978; Sillen and Kavanagh 1982; Connor and Slaughter 1984; Klepinger 1984). In addition, strontium isotope ratios in bones and teeth were employed to distinguish marine vs. terrestrial inputs to prehistoric human diets (Ericson 1985). Many of these early elemental studies addressed relationships between dietary variability and mortuary variability as a means to assess past social differentiation (Brown 1974; Gilbert 1977; Lambert et al. 1979; Schoeninger 1979; Blakely and Beck l98 1; Pate 1984). Stable carbon, nitrogen and sulphur isotope ratios in the collagen and non-collagenous protein components of bones and teeth record the relative amounts of marine vs. terrestrial foods and C 3 vs C 4 , plants in individual diets (Schoeninger and DeNiro 1984; Peterson and Fry 1987). Stable carbon and oxygen  isotope ratios in the inorganic carbonate and phosphate portions of bone and tooth apatite can supplement these organic analyses (Krueger and Sullivan 1984; Sponheimer and Lee-Thorp 1999). Initial archaeological applications involved stable carbon isotopes in bone collagen. These studies addressed the relative contribution of photosynthetically distinct plants, e.g. corn (C 3 ) vs. wheat (C 4 ), to prehistoric human diets (van der Merwe and Vogel 1978; Bender et al. 1981; van der Merwe 1982). Subsequent research involved stable carbon and nitrogen isotope analyses of prehistoric human bone collagen to infer relative consumption of marine vs. terrestrial foods (Norr; 1981, 1982; Chisholm et al. 1982; 1983; Schoeninger et al. 1983; Hobson and Collier 1984). More recently, stable oxygen isotopes have been employed to provide information about trophic level and diets based on browsing vs. grazing (Kohn et al. 1996; Wright and Schwarcz 1999). Because of the substantial difficulties associated with quantitative inferences regarding prehistoric human dietary composition from archaeological food remains and artefacts, chemical palaeodietary techniques involving analyses of human and faunal bones and teeth received great attention following their introduction in various parts of the world and became widespread in the archaeological and physical anthropological literature during the 1990s. Â