Strontium isotopes and concentrations in cremated bones suggest an increased salt consumption in Gallo-Roman diet

Abstract

The high temperatures reached during cremation lead to the destruction of organic matter preventing the use of traditional isotopic methods for dietary reconstructions. Still, strontium isotope (87Sr/86Sr) and concentration ([Sr]) analyses of cremated human remains offer a novel way to assess changing consumption patterns in past populations that practiced cremation, as evidenced by a large amount of new data obtained from Metal Ages and Gallo-Roman human remains from Destelbergen, Belgium. The Gallo-Roman results show significantly higher [Sr] and a narrower interquartile range in 87Sr/86Sr (0.7093–0.7095), close to the value of modern-day seawater (0.7092). This contrasts with the Metal Ages results, which display lower concentrations and a wider range in 87Sr/86Sr (0.7094–0.7098). This typical Sr signature is also reflected in other sites and is most likely related to an introduction of marine Sr in the form of salt as a food preservative (e.g. salt-rich preserved meat, fish and fish sauce). Paradoxically, this study highlights caution is needed when using 87Sr/86Sr for palaeomobility studies in populations with high salt consumption.

Sr analyses from only known Scandinavian cremation cemetery in Britain illuminate early Viking journey with horse and dog across the North Sea

“…Fractions of the bone digested samples were used to determine Sr and Ca content in the sample digests with a Thermo Scientific Element 2 sector field ICP mass spectrometer at the Vrije Universiteit Brussel (VUB), Belgium, in low ( 88 Sr) and medium ( 42 Ca) resolution using Indium (In) as an internal standard and external calibration versus various reference materials (SRM1400, CCB01). The strontium content were calculated by normalizing the calcium data to 40% by weight to account for organic loss (see [ 26 ]). The analytical precision of the procedure outlined above is estimated through repeated digestion and measurement of two internal bioapatite standards (ENF and CBA) and does not exceed 5% (1SD, n = 33 for CBA and n = 5 for ENF).…”

Comparison between strip sampling and laser ablation methods to infer seasonal movements from intra-tooth strontium isotopes profiles in migratory caribou

“…Bioavailable 87 Sr/ 86 Sr is incorporated to mammalian tissues through food and water consumed. During the transfer process from bedrock to animal tissues, 87 Sr/ 86 Sr is subjected to negligible fractionation 15 and thus, values observed in animal tissues should directly reflect the local bioavailable 87 Sr/ 86 Sr of the area where the animal fed during the tissue formation 13 , albeit with some potential influences of differential digestion or other aspects of food selection or preparation 16 – 18 .A recent effort has been made to produce local and global 87 Sr/ 86 Sr isoscapes based on intensive sampling of soil and biological material and/or modelling 14 , 19 , 20 . As 87 Sr/ 86 Sr varies in bedrock on a geological time scale, modern strontium isoscapes are relevant to explore past mobility, although anthropogenic influences that also affect environmental 87 Sr/ 86 Sr (e.g., fertilizers) should be taken into account 14 , 21 .…”