Nitrogen isotopes and the trophic level of humans in archaeology

Human and domesticate animal bone collagen δ¹⁵N values in prehistory differ generally by 3‰ or more from Neolithic to post- Roman times in Northwest Europe, leading to an assumed dietary animal protein fraction of 60–80% using a standard interpretation of δ¹⁵N values. We examine the assumptions on which this model rests and the limitations of our knowledge in the analysis of δ¹⁵N values in archaeology. We have developed a set of models which, with small changes made in assumptions (on the order of 1‰), can produce substantially lower estimates of the dietary animal protein fraction for given δ¹⁵N values. We consider the implications of various dietary animal protein fractions on agricultural carrying capacities and human population densities in prehistory.     

Stable Isotopic Evidence of Ancient Maya Diet at Caledonia,Cayo District,Belize

The skeletal remains of 18 individuals interred at the ancient Maya site of Caledonia (100 to 1000 C.E.), located in the Cayo District of Belize, w ere sampled for stable carbon and nitrogen isotope analysis in order to reconstruct their diet. Stable carbon and nitrogen isotope ratios in 18 bone collagen samples and stable carbon isotope ratios in bioapatite from 15 bone and 6 tooth enamel samples were assessed. Small sample sizes precluded the assessment of dietary variation with respect to age, sex, social status or time period among the Caledonia Maya. However, the sampled individuals consumed a varied diet consisting of maize, supplemented with some C₃ plants, terrestrial herbivores and/or lower order freshwater resources such as snails and molluscs and possibly maize‐fed animals. This dietary variability with an emphasis on maize is unsurprising given the biological diversity surrounding the site and the known importance of this crop to the ancient Maya. As expected, the isotopic values from Caledonia are similar to those from nearby sites from similar time periods. However, four individuals exhibit a marine dietary signature, possibly indicating inland trade of marine resources from coastal sites, or the migration of coastal people to Caledonia. This study demonstrates the validity of sampling small, fragmented collections from minor Maya centres in order to gain valuable insight into ancient Maya dietary practices. Copyright © 2013 John Wiley & Sons, Ltd.     

Dietary Variability During Bronze Age in Central Italy: First Results

This research aims at delineating the dietary practices in Central Italy during the Bronze Age. The study of food choices is a mean for investigating palaeoenvironmental agricultural and economic activities and social relationships, which have been little explored until now in Italy from this specific perspective. Recent researches have showed that the Middle Bronze Age is a crucial period of dietary changes in Italy. Following these first observations, we studied three Bronze Age sites in Tuscany and Latium: Grotta dello Scoglietto, Grotta Misa and Felcetone. Analyses of stable carbon, nitrogen and sulphur isotopes on 38 human and 22 animal collagen samples were performed. The results show three different dietary patterns. Data from Grotta dello Scoglietto (Early Bronze Age) indicate a high‐protein intake, with a probable consumption of fish. Additionally, sulphur results let us infer the presence of some non‐local people. Individuals from Felcetone (Initial phase of the Middle Bronze Age) show a terrestrial diet dominated by plant proteins, which suggests a low δ¹⁵N food intake, namely legumes, as well as C₄ plant, such as millet. Finally, values from Grotta Misa (Middle Bronze Age) highlight a mixed terrestrial diet and the consumption of millet. Given the variety of the obtained results, we are able to conclude that the transition from the Early to the Middle Bronze Age represents a moment of change, which is reflected by the presence of different dietary patterns. Copyright © 2015 John Wiley & Sons, Ltd.     

Diet and mobility in Middle Archaic Florida: stable isotopic and faunal evidence from the Harris Creek archaeological site (8Vo24), Tick Island

We explore diet and mobility in Middle Archaic Florida using human burials and faunal remains from the Harris Creek archaeological site (8Vo24) on Tick Island. We conducted stable carbon and oxygen isotopic (δ¹³C, δ¹⁸O) analyses of 50 human enamel samples and strontium isotopic (⁸⁷Sr/⁸⁶Sr) analysis of a subset of 10. Most individuals (46/50) subsisted on local freshwater and terrestrial resources, with relatively depleted δ¹³C values (C₃) and δ¹⁸O values matching those of central and north Florida water resources within the St. Johns River valley. Eight of 10 burials have local, within valley ⁸⁷Sr/⁸⁶Sr values. Two human burials yield marine δ¹³C and ⁸⁷Sr/⁸⁶Sr values, which we interpret as evidence for across valley movement from the coast. Another two individuals show depleted δ¹⁸O values, likely obtained from northern rivers. We also identified potential food resources and non-local foods from the Harris Creek faunal assemblage. We found six species with estuarine and marine habitat preferences; two of which, whelk and quahog, indicate that people of Harris Creek traveled to or traded with coastal areas.     

Stable carbon- and nitrogen-isotope ratios and electron spin resonance (ESR) g-values of charred bones: changes with heating and a critical evaluation of the utility of g-values for reconstructing thermal history and original isotope ratios

Changes in the stable carbon and nitrogen isotope ratios of modern bone samples heated to a variety of times and temperatures were used to determine the effect of heating on isotope ratios and the retention of organic matter in charred bones. For organic extracts produced by slow demineralization in weak acid, δ¹³C values were unchanged, while δ¹⁵N values increased by up to 5‰ and were primarily determined by heating temperature. Changes in the electron spin resonance (ESR) g-value of whole bone and organic extracts were also measured. For organic extracts from charred bones, the g-value was well-correlated with δ¹⁵N and temperature, suggesting that g-values could be used to estimate the charring temperature and original δ¹⁵N values of charred bones. Thus, g-values from demineralized extracts could be very useful in forensic investigations where it would important to reconstruct the thermal history of burned bones. Isotope ratios and g-values of demineralized extracts from four prehistoric components at three sites that produced cremated human bone were used to test whether the same approach can be applied to archaeological materials. While carbon isotope ratios of the prehistoric samples were similar to those of uncharred specimens, nitrogen isotope ratios were increased and the g-value corrections for nitrogen isotope ratios were not effective.     

Stable isotopes and diet at Ancient Kerma,Upper Nubia (Sudan)

Carbon and nitrogen stable isotope values were measured from bone collagen extracted from archaeological Nubian human (n = 54) and faunal (n = 61) populations from the site of Kerma, Sudan. Collagen suitable for isotopic analysis was extracted from 22 faunal and 48 human samples from the Eastern cemetery site, dated to the Middle Kerma (c. 2050–1750 BC) and Classic Kerma (c. 1750–1500 BC) periods respectively. The isotopic data indicate that the human dietary regimen included a mix of C₃ and C₄ plant-derived components, with a larger C₄ component than previously reported in archaeological Egyptian Nile Valley populations. Elevated δ¹⁵N values are attributed to consumption of dietary resources from a ¹⁵N-enriched terrestrial ecosystem. The faunal isotope data also indicate the consumption of C₃ and C₄ plants. The large range of δ¹³C values measured in both the human and faunal samples supports previous work suggesting that a significant portion of the populations buried at Kerma may have originated elsewhere, further confirming the Nile Valley as a major corridor for population movement in the region.     

Archaeological excavations at Bosutswe,Botswana: cultural chronology,paleo-ecology and economy

Excavations at the site of Bosutswe on the eastern edge of the Kalahari Desert in Botswana have uncovered over 4 m of deposit ranging in age from CE 700 to 1700. Our research has produced quantitative and qualitative measures of the material and ecological dimensions that structured the everyday actions and behaviors through which social identities were constituted, maintained, and transformed during the period when the polities of Toutswe, Mapungubwe, Great Zimbabwe and Khami rose to power. By examining the material dimensions that underlay shifting relations of production, exchange, and social stratification we are able to contextualize the social judgments that ascribed value to material goods and food ways, while specifying the ways these were used to create and naturalize social relationships and power differentials. Stable isotope analyses, combined with evidence of vitrified dung, further enable us to suggest changes in herd management strategies used by the inhabitants of the site to compensate for ecological changes brought about by long-term occupation, while at the same time enabling them to economically tie subordinates to them as social divisions became more rigidly defined after CE 1300. The cultural and economic changes that took place at Bosutswe thus directly impact our understanding of the social transformations that immediately preceded contemporary configurations of ethnicity in Botswana.     

Correlation between modern plant δN values and activity areas of Medieval Norse farms

This further nitrogen isotopic study of Greenlandic Norse archaeological sites provides new evidence of the affect of past human activity on modern plant δ¹⁵N values. Grass samples were taken from a number of spatially defined features at four Norse farms and one site interpreted to be a seasonally occupied herding station (sæter). At the farms, un-naturally high δ¹⁵N values were found for plants from each sampled feature, including those from the likely infields and a churchyard. At the sæter no strong isotopic effect was expected and none was found. Comparing the data from the farms we found that the average plant δ¹⁵N values were similar for features that were functionally alike. We conclude from these observations, that the unusually high plant δ¹⁵N values reflect the strong conservation of the isotopic composition of the nitrogenous materials deposited in the past, and the magnitude of the values reflects the amount of this material admixed in the soil. The results confirm previous exploratory studies of this isotopic effect and further demonstrate its potential value as an archaeological tool.     

Molecular and isotopic traces of cooking and consumption of fish at an Early Medieval manor site in eastern middle Sweden

This paper is a presentation of a comparison between prehistoric food culture signals obtained through analyses of lipid food residues in pottery, i.e. pottery-use, from settlement remains on one hand and bone chemical analyses of human skeletal remains from an adjacent and contemporary cemetery on the other. The materials derive from the Early Medieval site Tuna in Alsike par., Uppland, Sweden. The results show a discrepancy between the two food signals and it is argued that pottery-use do not by necessity reflect everyday diet. But it is also argued that the integration of several food signals together with contextual archaeological data is a fruitful way to begin to understand the complexity of prehistoric cultures of food.     

The consilience of historical and isotopic approaches in reconstructing the medieval Mediterranean diet

During the Middle Ages, the economies of Europe, the religious directives involving dietary requirements, and the general human subsistence base were transformed. These complicated and intertwined issues are starkly revealed in an isotopic study of two inland Italian human populations that are separated by approximately 850 years in time. Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic values observed in human dentin and bone collagen from the sites of early medieval Castro dei Volsci and late medieval Rome are consistent with diets that differed substantially. As the North Atlantic opened to fishing and food preservations methods improved, Mediterranean peoples increased their fish consumption dramatically, and in doing so, met the religious directives of the Catholic Church. By analyzing both teeth and bone collagen within individuals, long-term feeding behaviors are documented, and the utility of last erupted teeth collagen as sources of adult dietary information is established. This study offers the first physical evidence of this new economic reality linking the Atlantic and Mediterranean economies at the end of the Middle Ages.