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

Abstract

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.

Passports from the past: Investigating human dispersals using strontium isotope analysis of tooth enamel

“…discrimination against Sr 2+ in favour of Ca 2+ , at each successive trophic level in both marine and terrestrial environments , Comar et al 1957, Elias et al 1982, 2561. This works well with single-component diets but, in practice, has proved difficult with multi-component diets (Burton and Wright 1995). Mineral metabolism is an extremely complex interaction between many variables that affect trace element bioavailability.…”

“…The ratio of Sr/Ca is widely used in archaeological and modern food chain studies to identify the trophic level, and hence types of food, that an individual exploited (Blum et al 2000, Burton and Wright 1995, Elias et al 1982, Sealy and Sillen 1988. There is a progressive biopurification, i.e.…”

“…Individual strontium metabolism is, therefore, dependent upon many factors and synergisms/antagonisms, only one of which is the amount of calcium in the diet. For example, strontium-uptake is suppressed in high-calcium or protein-rich diets (Aufderheide 1989, Burton and Wright 1995, Lambert and Weydert-Homeyer 1993, Underwood 1977, and due to the low levels in milk, by consumption of dairy produce (Ezzo 1994). Strontium-uptake is increased in high phytate and fibre diets which actively reduce calcium absorption (Lambert and Weydert-Homeyer 1993) and accordingly, herbivorous diets (Alexander andNusbaum 1959, Underwood 1977).…”

Nutritional ecology and diachronic trends in Paleolithic diet and health

“…[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] These proxy data may illuminate trends in dietary diversity during the Paleolithic, including general trends in essential nutrient intake. For example, a tendency in the archeological record away from the consumption of primarily terrestrial mammals toward the consumption of more equal proportions of terrestrial mammals, shellfish, fish, birds, and plants would indicate healthier populations and positively affect demography trend.…”

On the possibilities of ICP-AES for analysis of archaeological bones

“…Several analytical techniques are used in the analysis of archaeological bones: (a) inductively coupled plasma atomic emission spectroscopy (ICP-AES) (see [3,5,10]); (b) atomic absorption spectroscopy (AAS) (see [11][12][13][14]); (c) instrumental neutron activation analysis (INAA) [see [15][16][17][18]; (d) inductively coupled plasma mass spectroscopy (ICP-MS) [19], (e) and more often the combinations of AAS/ICP-AES [20][21][22][23] and ICP-AES/XRF [1,2,7]. The ICP-AES technique (see [1][2][3]) is gaining popularity in the analysis of bone materials.…”