Diet and status at Chalcatzingo: Some empirical and technical aspects of strontium analysis

Abstract

Determination of the levels of particular trace elements preserved in bone provides a potential pathway for reconstructing the diet of extinct primate species and archaic human groups. Strontium is one of the most useful trace elements for dietary reconstruction but several empirical properties of strontium must be considered during the interpretation of results. (1) Strontium is distributed unevenly throughout the physical environment. (2) Plants, in general, do not discriminate against strontium. (3) During ionic transfer across biological membranes, strontium is discriminated against by terrestrial vertebrates. (4) It is unlikely that strontium would be selectively removed from bone mineral during diagenesis. A particular difficulty in trace element analysis is caused by interaction between analytical technique and sample matrix. To assess this problem the skeletal population from Chalcatzingo was analyzed by two techniques: atomic absorption spectrometry and neutron activation analysis. The results from the two techniques compared favorably indicating that the pattern of bone strontium levels could be accepted as an accurate reflection of the distribution of bone strontium within the population. After demonstrating the internal accuracy of the results, the bone strontium level and position of social rank within Chalcatzingo were compared. Ethnographic and archaeological evidence on chiefdoms and states indicate that dietary differences in the amount of meat consumed occur between social ranks. The relative social ranks were reconstructed by using a “pattern analysis” of the burial goods accompanying each individual. The individuals accompanied by jade had the lowest mean bone strontium level (X¯=532). Those individuals buried with a shallow dish had a slightly higher level (X¯=635). A third group, which had no grave goods, had the highest mean bone strontium level (X¯=700) which suggests that their diet contained less meat than was available to the rest of the community.