Nonlinearity in the relationship between bone Sr/Ca and diet: paleodietary implications

Strontium in archaeological human bones is widely, almost paradigmatically, used as a measure of the relative dietary abundances of plants and meat. Quantitative modeling reveals, however, that there is not a simple proportional relationship between bone strontium and the dietary plant/meat ratio. While knowledge of specific foods and their compositions may permit accurate calculation of average bone strontium levels, knowledge of bone strontium does not inversely allow accurate calculation of specific foods. Although bone strontium quantitatively reflects the average dietary Sr/Ca ratio, it is disproportionately sensitive to high-calcium foods and can be easily affected by minor dietary constituents and culinary practices. Bone strontium, and by analogy, barium, should be seen as a reflection of the high-mineral dietary components rather than a quantitative index of trophic position.