Content area
Abstract
This study was carried out in order to address two questions concerning the use of strontium as a dietary indicator. First, is it feasible to compare bone strontium levels from different sites within a given region in order to make dietary inferences? That is, can environmental variation in strontium be detected, and if present, controlled for? Second, if valid comparisons can be made, what patterns of dietary change are indicated for Middle and Late Woodland populations in southern Ontario?
Five populations from four sites were chosen for study. The Serpent Mounds site included two components, the mound burials, dated A.D. 100, and the pit burials, dated A.D. 1100. The Fairty ossuary is dated A.D. 1350-1400, the Kleinburg ossuary dates to A.D. 1600 and the early historic Ossossane ossuary is dated A.D. 1636.
Ninety-eight human ribs and nineteen animal bones were analysed for the trace elements strontium, rubidium, zirconium and yttrium. Twenty-five human and eight animal bones were analysed for major elements including calcium, phosphorus, silicon, aluminum, iron, manganese, titanium, magnesium and potassium. Soil samples from each site were analysed for all elements. All analyses were performed using a crystal dispersive x-ray fluorescence spectrometer.
Results indicate little or no variation in available strontium in the antemortem environment. Variation in the postmortem environment can be detected from examining levels of zirconium, calcium and phosphorus, and the ratio of calcium to phosphorus. Zirconium in bone indicates soil contamination, and abnormally high ratios of calcium to phosphorus indicate contamination from calcium carbonate. Once these abnormalities are corrected for, comparisons among sites and dietary inferences can be made.
Among the five populations, the highest strontium levels were found in the Serpent Pits group. The Serpent Mounds people were slightly lower, followed by Fairty, Kleinburg and Ossossane. These findings suggest that with the adoption of maize horticulture, populations became less dependent on strontium rich foods such as nuts and molluscs, and more dependent on low strontium foods such as maize and squash. From a cultural perspective, it appears that the subsistence shift occurred mainly in foods procured by women.
