THE ISOTOPIC COMPOSITION AND DIAGENESIS OF HUMAN BONE FROM TEOTIHUACAN AND OAXACA, MEXICO

We analyzed archaeological human bone from Teotihuacan and Oaxaca, dat ing from about 300 BC to 750 AD to distinguish ethnic groups within Te otihuacan using oxygen isotopes. Sixty-eight analyses of bone phosphat e delta(18)O were made of 64 individuals. In addition to oxygen isotop ic analysis, the bones were examined using FTIR spectra, with some add itional DNAA and ICP-MS analyses. Little change occurs in the bone apa tite until the amount of collagen (as combustible organics) has been r educed considerably, when the bone becomes softer and FTIR crystallini ty increases. The delta(18)O of the phosphate (delta(p)) appears to be unaltered even after extensive diagenesis and, probably, solution. On FTIR plots the relative area of the carbonate peak to the main phosph ate peak decreases with diagenetic level. The bones absorb some metals rapidly after burial, for example uranium, which then leach out as di agenesis of the bone apatite progresses. Other metallic elements incre ase irregularly in concentration as alteration proceeds.