Bone chemistry and prehistoric diet: strontium studies of laboratory rats

Reading children's teeth to reconstruct life history and the evolution of human cooperation and cognition: The role of dental enamel microstructure and chemistry

Studying infants in the past is crucial for understanding the evolution of human life history and the evolution of cooperation, cognition, and communication. An infant's growth, health, and mortality can provide information about the dynamics and structure of a population, their cultural practices, and the adaptive capacity of a community. Skeletal remains provide one way of accessing this information for humans recovered prior to the historical periods. Teeth in particular, are retrospective archives of information that can be accessed through morphological, micromorphological, and biogeochemical methods. This review discusses how the microanatomy and formation of teeth, and particularly enamel, serve as archives of somatic growth, stress, and the environment. Examining their role in the broader context of human evolution, we discuss dental biogeochemistry and emphasize how the incremental growth of tooth microstructure facilitates the reconstruction of temporal data related to health, diet, mobility, and stress in past societies. The review concludes by considering tooth microstructure as a biomarker and the potential clinical applications.

Historical overview and new directions in bioarchaeological trace element analysis: a review

Given their strong affinity for the skeleton, trace elements are often stored in bones and teeth long term. Diet, geography, health, disease, social status, activity, and occupation are some factors which may cause differential exposure to, and uptake of, trace elements, theoretically introducing variability in their concentrations and/or ratios in the skeleton. Trace element analysis of bioarchaeological remains has the potential, therefore, to provide rich insights into past human lifeways. This review provides a historical overview of bioarchaeological trace element analysis and comments on the current state of the discipline by highlighting approaches with growing momentum. Popularity for the discipline surged following preliminary studies in the 1960s to 1970s that demonstrated the utility of strontium (Sr) as a dietary indicator. During the 1980s, Sr/Ca ratio and multi-element studies were commonplace in bioarchaeology, linking trace elements with dietary phenomena. Interest in using trace elements for bioarchaeological inferences waned following a period of critiques in the late 1980s to 1990s that argued the discipline failed to account for diagenesis, simplified complex element uptake and regulation processes, and used several unsuitable elements for palaeodietary reconstruction (e.g. those under homeostatic regulation, those without a strong affinity for the skeleton). In the twenty-first century, trace element analyses have been primarily restricted to Sr and lead (Pb) isotope analysis and the study of toxic trace elements, though small pockets of bioarchaeology have continued to analyse multiple elements. Techniques such as micro-sampling, element mapping, and non-traditional stable isotope analysis have provided novel insights which hold the promise of helping to overcome limitations faced by the discipline.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12520-020-01262-4.

Health risk assessment of heavy metals and strontium in groundwater used for drinking and cooking in 58 villages of Prakasam district, Andhra Pradesh, India

Groundwater is one of the most important sources of water for drinking and cooking in rural India. A total of 382 groundwater samples were collected from 58 villages and analyzed for HMs and Sr by inductively coupled plasma mass spectrometer. The average concentrations of HMs and Sr in water was in the order of strontium (Sr) > arsenic (As) > chromium (Cr) > lead (Pb) > mercury (Hg) > cadmium (Cd). Out of 58 villages, 21, 37, 35, 35, 35 and 39 villages had Cr, As, Cd, Hg, Pb and Sr higher (WHO limit) than their respectively permissible levels. Health risk assessment of HMs and Sr for humans revealed that the non-carcinogenicity hazard quotients (HQ_i+d) for HMs and Sr were higher than unity for adult and children. The hazard index (HI) was 531.066 for adult and 902.926 for children. The HI > 1 was observed in 45 villages for adults and 56 villages for children. The lifetime cancer risk in adult for As_i, As_d, and Pb_i in 36, 25 and 23 villages, whereas in children was 42, 20 and 22 villages, respectively. In conclusion, the health risks arising from consumption of groundwater containing HMs and Sr indicated that there is a significant carcinogenic risks for adult and children. This is the first attempt to provide information on the health risks of Sr in drinking water in India. The present findings can be useful for the development of potential strategies for risk control and management.

Stable isotope and trace element studies on gladiators and contemporary Romans from Ephesus (Turkey, 2nd and 3rd Ct. AD)--mplications for differences in diet

The gladiator cemetery discovered in Ephesus (Turkey) in 1993 dates to the 2^nd and 3^rd century AD. The aim of this study is to reconstruct diverse diet, social stratification, and migration of the inhabitants of Roman Ephesus and the distinct group of gladiators. Stable carbon, nitrogen, and sulphur isotope analysis were applied, and inorganic bone elements (strontium, calcium) were determined. In total, 53 individuals, including 22 gladiators, were analysed. All individuals consumed C₃ plants like wheat and barley as staple food. A few individuals show indication of consumption of C₄ plants. The δ¹³C values of one female from the gladiator cemetery and one gladiator differ from all other individuals. Their δ³⁴S values indicate that they probably migrated from another geographical region or consumed different foods. The δ¹⁵N values are relatively low in comparison to other sites from Roman times. A probable cause for the depletion of ¹⁵N in Ephesus could be the frequent consumption of legumes. The Sr/Ca-ratios of the gladiators were significantly higher than the values of the contemporary Roman inhabitants. Since the Sr/Ca-ratio reflects the main Ca-supplier in the diet, the elevated values of the gladiators might suggest a frequent use of a plant ash beverage, as mentioned in ancient texts.

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

Strontium isotopes are a powerful tool which provide information about provenance directly from the tissues of humans rather than the grave context and burial goods. Geographical variation in strontium isotopes is primarily controlled by the underlying geology but there are many other factors that need to be considered before migratory individuals can be identified. Consequently, despite many studies which have shown that the method works well, it is clear that much remains to be clarified and it will not work for every question or in every place. It rests on the assumption that people were sourcing their food locally and that there is a measurable strontium isotope difference between the place the person migrated from and the place they migrated to. As migrants may deliberately seek out familiar soil types and terrains in their new homeland, some questions surrounding major migration events may prove intractable for this technique. Other factors that can create heterogeneity or homogeneity leading to false positives or false negatives, such as human choices or coastal subsistence, are explored and the metabolism of strontium into human tooth enamel is discussed. Several models of land-use choices by humans are presented to highlight the subtleties inherent in the isotope data and these are used to interpret archaeological human isotope ratios from three studies.

Multielemental accumulation and its intracellular distribution in tissues of some aquatic birds

This study was aimed at determining multielemental concentration and its intracellular distribution in selected tissues of cormorant and waterfowl species. Non-essential elements such as Hg, Tl, Cd, Pb and V in tissues were generally consistent with those in ingested items, indicating the significance of food sources of non-essential metal accumulation in great cormorants and mallards. Great cormorants and four waterfowl species examined reflected natural background levels of toxic metals such as Cd, Hg and Pb as well as some essential elements, indicating no specific metal exposure from local sources. Most of Cu, Zn, Se, Rb, Ag, Cd, Cs, and Hg contents were present in the hepatocytosolic fraction, whereas a large percentage of V and Mo were present in insoluble fraction in great cormorant, mallard, and spot-billed duck. The major role of these subcelluar fractions in elemental regulation accounts for the high percentage contribution of each cellular fraction to the total metal contents. Cadmium and Cu are chiefly sequestered through binding to metallothioneins (MTs) of hepatocytosolic fraction in these three avian species. Both MTs and high-molecular-weight substance (HMWS) for Zn and low-molecular-weight substance (LMWS) for Rb were also involved in their sequestration in cytosolic fractions. Relatively different species-specific cytosolic substances were responsible for varying degrees of Ag, Mn, and Co accumulation. It is worth noting that these intracellular metal levels in birds are closely regulated by metal-associated cellular constituents. Therefore, risk assessment studies of metal accumulation in such wild birds should take intracellular metal distribution and specific cellular constituents into account.

Rickets and soil strontium

The subjects of this study were children aged 6-60 months living in villages in the Ulas Health Region, Sivas. The villages were divided into two groups according to the amount of strontium in the soil: region 1, > 350 ppm, 650 children; region 2, < 350 ppm, 1596 children. Overall, the prevalence of one or more clinical signs of rickets was 22.9%. The prevalence in region 1 was 31.5% and that in region 2, 19.5%. These values were significantly different (p < 0.001). When other variables which may be relevant to the occurrence of rickets were taken into account, the difference in prevalence persisted. The results suggest that in villages where nutrition is mainly based on grain cereals the presence of strontium in the soil will increase the prevalence of rickets significantly. As a preventive measure, a greater proportion of the foods given to children in these villages should be derived from animal origin, and cereals and drinking water supplies should be obtained from villages with a low soil strontium content, or calcium supplements should be given.

The effects of dry ashing on the composition of human and animal bone

Elemental analysis of archaeological bones, particularly for elements such as fluorine, strontium, and zinc, has been carried out for many years, with the aim of determining their age or relating their composition to diet. Bone samples are commonly dry ashed before analysis to remove organic material and render them more readily soluble. In this study, the recoveries of strontium, zinc, and nine other elements are reported for a range of ashing times and temperatures. Recoveries of sodium, potassium, fluorine, chlorine, bromine, and zinc are significantly affected by ashing under some conditions, but recoveries of strontium, calcium, magnesium, and manganese are not.

Bone strontium in pregnant and lactating females from archaeological samples

Because plants and animals consume or absorb different amounts of strontium and calcium, anthropologists are able to use strontium/calcium (Sr/Ca) ratios from archaeologically recovered human bone to estimate the relative contributions of meat and plants to paleodiets. Often females exhibit higher Sr/Ca ratios than males, a fact usually attributed to lower meat intake among women. However, in vivo and in vitro experiments with laboratory animals show that pregnancy and lactation elevate maternal bone strontium and depress maternal bone calcium because 1) strontium is discriminated against in favor of calcium in the transport of ions to the placenta and mammary glands and 2) pregnancy and lactation facilitate absorption of alkaline earth metals from the gut. In this study, bone Sr/Ca ratios and strontium concentrations were compared between reproductive-age females, postmenopausal females, and adult males from two late prehistoric Native American sites in Georgia: the King site (N = 43) and the Etowah site (N = 51). At the King site, the mean Sr/Ca ratio of females was over 14% greater than that of males. At Etowah, the mean strontium level of reproductive-age females exceeded that of postmenopausal females by almost 25%. Most of the difference, it is argued, is due to pregnancy and lactation. A dietary preference among pregnant and lactating women for foods high in alkaline earths, particularly nuts and corn, may also be partially responsible. Until we assess the influence variables other than nutrition exert on trace element concentrations, our reconstructions of paleodiets will be suspect.