Stable carbon and nitrogen isotope ratios of bone collagen: Variations within individuals,between sexes,and within populations raised on monotonous diets

The stable carbon and nitrogen isotope ratios of collagen of seven bones from each of three rabbits raised on a monotonous diet, and of two bones from each of eight female and seven male mink raised on another monotonous diet, were determined. The ranges of δ¹³C values and δ¹⁵N values were 0·5‰ and 0·6‰ for the rabbit bones and 1·0‰ and 1·4‰ for the mink bones. Uncertainties in the δ¹³C and δ¹⁵N values for prehistoric human diets estimated from the isotopic composition of collagen from the small numbers of bones which are typically available for analysis, and thus likely to be of the order of ±1‰.     

The effect of growth on stable nitrogen isotope ratios in subadult bone collagen

Stable nitrogen isotopes have been used to reconstruct infant feeding practices as nursing infants have elevated δ¹⁵N ratios compared with their mothers. However, infancy is also a time of rapid growth, which may alter nitrogen isotope diet‐to‐tissue spacing. Several studies have documented a decrease in δ¹⁵N during growth in tissues with relatively fast accretion rates. This study investigates the effect that the growth of long bones, via collagen accretion, has on δ¹⁵N ratios. Long bones from individuals aged seven to nineteen years were obtained from a protohistoric ossuary in Ontario, Canada. Analysis of juveniles and adolescents permitted the examination of growth in a group who were not also nursing. It is concluded that a nitrogen isotope growth effect is not detectable in bone collagen from juveniles and adolescents, because: (1) δ¹⁵N ratios are not significantly different among the epiphyses, metaphyses and diaphysis of a growing long bone; (2) δ¹⁵N ratios are not significantly different between faster‐growing versus slower‐growing metaphyses; and (3) δ¹⁵N ratios are not significantly different between bones (or areas of a bone) that are still undergoing growth, versus bones that have ceased growing. The relatively slow speed of collagen accretion may explain why a growth effect is not manifested. Ultimately this research lends support to the use of nitrogen isotopes from bone collagen for infant feeding reconstructions. Copyright © 2009 John Wiley & Sons, Ltd.     

The impact of manuring on nitrogen isotope ratios in cereals: archaeological implications for reconstruction of diet and crop management practices

Recent archaeological studies of human diet have used stable nitrogen isotope ratios (δ¹⁵N) from human bone collagen to infer the relative importance of terrestrial plant and animal foods. This approach is based on widely observed enrichment of δ¹⁵N up the food chain, plants having distinctly lower values than the herbivores that consume them. Studies of early farming diets in Britain, Denmark and Germany have tended to detect relatively high δ¹⁵N values (e.g. c. +9‰), interpreted as evidence of a diet largely based on animal products, though archaeobotanical evidence for crop cultivation (e.g. carbonised cereal grain and chaff) is widespread. This paper investigates the impact of manuring on δ¹⁵N values in modern cereals, and of charring on these cereal values. The results from two long-term experiments demonstrate that manuring significantly raises δ¹⁵N in cereal grain and chaff. Depending on manuring levels and frequency, it appears that human diets with a major component of such grain would conventionally be interpreted as indicating a largely animal-based diet or a mixed plant/animal diet. Moreover, preliminary analyses of experimentally charred grain and chaff from manured and unmanured conditions are promising for the extraction of reliable ancient δ¹⁵N values from archaeobotanical cereal remains. The wider implications of these results, and the need for further work, are discussed.     

Paleonutritional and paleodietary survey on prehistoric humans from Las Cañadas del Teide (Tenerife,Canary Islands) based on chemical and histological analysis of bone

The aim of the present study is to perform a paleodietary and paleonutritional survey on 17 individuals buried in accordance with the prehispanic ritual in the central plateau of the island Tenerife, called Las Cañadas del Teide. We recorded hydrogen, nitrogen and carbon isotope compositions of human bone collagen, bone barium and strontium, and histomorphometrically assessed trabecular bone mass (TBM). Bone trace elements and TBM were compared with reference data derived from a modern sample consisting of 13 individuals. In addition, δ¹⁵N and δ¹³C values were determined in several modern indigenous plants, bone collagen of prehistoric domestic animals (goat and pig), and prehistoric wild animals (a giant lizard, Gallotia goliath and a giant rat, Canaryomis bravoi), which represent food sources potentially consumed by the prehistoric population of the Island. The carbon stable isotope composition of bone collagen ranged between ?20.5 and ?18.6‰ (VPDB), indicating a diet based on C₃ plants. Nitrogen isotope values ranged from 8.2 to 12.4‰ (AIR), suggesting a general meat-enriched diet, most likely domestic goats, of higher level consumers. Hydrogen isotope values ranged from ?18 to +4‰, whereas log Ba/Sr was greater than ?0.40 in the vast majority of cases. TBM showed a tendency to osteoporosis in 30% of the individuals analyzed. C-14 dating showed that two burial sites, including 5 individuals, belonged to the post-conquest era (after the 15th century), despite a fully “prehispanic” burial ritual, which lends credenceto the oral tradition that some of the prehispanic population fled to the highlands at the time of the Spanish conquest, and lived there during decades or even centuries. These individuals showed lower δD, δ¹³C and δ¹⁵N, and higher log Ba/Sr values than those buried before the Spanish conquest, suggesting dietary differences between the two groups. Also, women showed a trend to a higher consumption of vegetables than men.     

Dietary reconstruction in Migration Period Central Germany: a carbon and nitrogen isotope study

This study presents bone collagen carbon and nitrogen isotope data from the Migration Period cemeteries (fifth/sixth century AD) of Obermöllern and Rathewitz in Central Germany. The human average δ ¹³C ratios of ?19.8?±?0.3 ‰ and δ ¹⁵N ratios of 9.6?±?0.9 ‰ (n?=?43) reflect a mixed diet in a temperate C3-based ecosystem without significant difference between the two sites. The average offset between human and faunal δ ¹³C and δ ¹⁵N values indicates a significant contribution of plant food to the human diet that has different isotope ratios from the forage of the animals. It furthermore suggests the influence of land management on the δ ¹⁵N values. One adult male from Obermöllern stands out due to his elevated nitrogen isotope ratio, body height, grave goods, and burial position. The collagen isotope data of this study are comparable with data from other central European sites and confirm rather stable communities with moderate variation in the environmental conditions of arable land.     

Calcium isotopes in archaeological bones and their relationship to dairy consumption

The calcium isotope ratios (δ^44/42Ca) of bones from humans and fauna from three archaeological sites, Taforalt, Abu Hureyra, and Danebury, are evaluated in order to assess whether calcium isotope ratios of bones can be used to detect dairy consumption by adult humans. At each site the fauna δ^44/42Ca is the same regardless of species, while the humans have lower δ^44/42Ca than the local animals by 0.24–0.41‰ (site means). However we cannot ascribe this difference to dairy consumption, given this human–faunal difference also occurs in Epipalaeolithic and Mesolithic adult humans, where dairy consumption is unlikely. Rather, this difference appears to be a result of differences in metabolic processes or other aspects of diet between humans and fauna. Minimal isotopic change in sequential acid leaches of bone powders and consideration of the high calcium concentration in bone suggest that bone calcium isotope ratios are not substantially affected by diagenetic change.     

Palaeoenvironmental and chronological investigations of the Magdalenian sites of Goyet Cave and Trou de Chaleux (Belgium), via stable isotope and radiocarbon analyses of horse skeletal remains

Trou de Chaleux and Goyet are caves situated less than 30 km apart in Belgium that contain stratified Magdalenian artefacts and butchered faunal remains. Published radiocarbon dates suggest that both sites were contemporaneously occupied during to the Late-glacial interstadial. It has previously been suggested that the Trou de Chaleux Late-glacial faunal remains might be slightly older than those at Goyet Cave, and that Trou de Chaleux has two phases of occupation during the Late-glacial interstadial. However, the limited number of radiocarbon dates currently available makes it impossible to determine whether the sites are truly contemporaneous, and the assessment of their absolute chronologies is complicated by a plateau in the calibration curve. In this paper, bone collagen δ¹³C and δ¹⁵N signatures of horse bones from the two sites are used to reconstruct local palaeoenvironments. We hypothesise that if occupations at the two sites were contemporaneous, the horse collagen δ¹³C and δ¹⁵N isotope signatures from both sites will be similar, since comparable carbon and nitrogen isotopic values would reflect similar diets, ecologies and environments. To provide clear dating parameters, new AMS radiocarbon determinations are also presented. Results show that horse collagen δ¹³C and δ¹⁵N isotope signatures at the two sites are different, indicating that the populations were not subject to similar diets, ecologies and environments. The new radiocarbon dates confirm that the horse bones from Trou de Chaleux date to the Late-glacial interstadial, but they also show that in Goyet Cave Horizons 1 and 2, older horse remains dating to ca. 32?000–27?000 ¹⁴C yr BP are mixed with Late-glacial horse remains. The δ¹⁵N values of the Goyet Cave horse bones radiocarbon dated to the Pleniglacial are substantially higher than those that have Late-glacial radiocarbon dates. Therefore, we now hypothesise that the majority of the horse bones isotopically analysed from Goyet Cave Horizon 1 are Pleniglacial in age. Statistical analysis of the radiocarbon dates indicates that the Late-glacial occupation at the two sites was contemporaneous, and that while there may appear to be two phases of occupation at Trou de Chaleux, this may be an artefact of the radiocarbon calibration curve.     

Dietary change in Fijian prehistory: isotopic analyses of human and animal skeletal material

We examine evidence for prehistoric diet in the Fiji Islands through the analysis of stable isotope ratios (δ¹³C and δ¹⁵N) for 26 samples of human and animal bones from various archaeological sites, time periods, and local environments. The oldest individuals in this study, dating to about 2700 BP and living on the small island of Waya, consumed a predominantly marine-based diet. Subsequent populations on this island showed reduced consumption of marine resources, with greater reliance on terrestrial ones, throughout the cultural sequence. In contrast, populations of humans and pigs living inland on Viti Levu, the largest island, relied on terrestrial resources since at least 1500 BP. Thus, our results suggest that human and pig diets throughout Fijian prehistory relied variably on marine or terrestrial resources, and this distinction is largely a product of geography. This finding and our analyses provide a model for understanding ancient diets in Remote Oceania.     

The effect of charring and burial on the biochemical composition of cereal grains: investigating the integrity of archaeological plant material

Stable isotope analysis of charred archaeobotanical cereal grains has the potential to provide direct evidence of crop growing conditions in the past and to refine palaeodietary predictions. If isotope values of archaeobotanical material are to be considered robust, it is necessary to characterise the compositional changes associated with their charring and burial. This study used a suite of analytical techniques, including FT-IR and solid state ¹³C NMR, to characterise changes in the biochemical composition of modern einkorn grains with heating at 230 °C for 2 h, 4 h, 8 h and 24 h, encompassing conditions that replicate their undistorted ancient counterparts. The biochemical composition of archaeobotanical charred einkorn grains was also investigated by FT-IR and solid state ¹³C NMR in order to assess the changes in composition which occur during burial. Results of FT-IR and solid-state ¹³C NMR show that heating of modern einkorn grains resulted in Maillard reactions between cereal proteins and starch, forming high molecular weight melanoidins, which contain both alkyl and aromatic carbon. Loss of low molecular weight carbon and nitrogen-containing volatiles resulted in a slight but non-systematic increase in the δ¹³C values and a systematic increase of 0.8‰ in the δ¹⁵N values of the charred einkorn grains. Solid-state ¹³C NMR shows that the ancient charred einkorn grains consisted entirely of aromatic carbon and retained a similar proportion of nitrogen to their modern 24 h charred counterparts, despite a significantly lower concentration of amino acids. This indicates that the amino acid nitrogen in the ancient charred grains was retained in the stable melanoidins whose polymeric structure makes them resistant to subsequent degradation.     

Effect of heating on the stable carbon and nitrogen isotope ratios of bone collagen

The effects of heat on the stable carbon and nitrogen isotopic ratios of collagen in bone were studied. Boiling or roasting did not change the δ¹³C and δ¹³N values by more than 1‰. More extreme heating, such as might occur if bones were burned or a body cremated, shifted δ¹³C and δ¹⁵N values by as much as 5 and 4‰ respectively. These large shifts were accompanied by changes in the atomic carbon-to-nitrogen ratios of the collagen. These results indicate that collagen samples extracted from prehistoric bones which display anomalous atomic carbon-to-nitrogen ratios may have been subjected to heating extreme enough to have altered their ${}^{13}\text{C}{}^{12}\text{C}$ and/or ${}^{15}\text{N}{}^{14}\text{N}$ ratios and therefore should not be used for dietary reconstruction.     

The Whole Tooth and Nothing but the Tooth: Or why Temporal Resolution of Bone Collagen May Be Unreliable

The carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios of human bone collagen have been used extensively over the last 40 years to investigate the diet of past populations. It has become apparent that bone collagen can give an unreliable temporal dietary signature especially in juveniles. With higher temporal resolution sampling of collagen from tooth dentine, it is possible to identify short-term changes in diet previously invisible in bone. This paper discusses the inherent problems of using bone collagen for dietary studies and suggests better sample choices, which can make our interpretations more robust, using breastfeeding and weaning as an example.     

Stable isotope analysis of human and animal remains from the Late Upper Palaeolithic site of Balma Guilanyà, southeastern Pre-Pyrenees,Spain

Stable isotope analysis of carbon (¹³C/¹²C) and nitrogen (¹⁵N/¹⁴N) was performed on collagen extracted from three human and five herbivore bone and tooth samples from the Late Upper Palaeolithic site of Balma Guilanyà (Catalonian Pre-Pyrenees, Spain). Contextual and palaeoecological data as well as radiocarbon dates indicate that the studied occupation phase took placed during the Bolling/Allerod interstadial (GI-1a event). The human remains were co-mingled without any anatomical association, corresponding to a minimum number of three individuals, and it was not possible to determine if the three analyzed samples are from one or more individuals. The mean isotope values obtained from the human remains are δ¹³C = −19.8‰ and δ¹⁵N = 6.7‰, while those of the large herbivores (red deer and wild goat) were −19.8‰ and 1.7‰ for δ¹³C and δ¹⁵N respectively. This indicates that the main source of protein in the diet of the Balma Guilanyà human(s) came from terrestrial herbivores. There is no zooarchaeological or isotopic evidence for the consumption of freshwater or marine resources at the site, which lies 80 km from the present Mediterranean coast. The low δ¹⁵N values observed in both human and animal samples correspond to a trend reported by other researchers working in northwestern Europe: a significant δ¹⁵N reduction in collagen from bones datable within 20,000–10,000 BP, followed by a rise to present values in the Early Holocene. This phenomenon, generally attributed to climatic and/or pedological processes, had not been previously observed in the Mediterranean region and, until now, was thought to be restricted to northern Europe.     

Isotopic evidence for the reconstruction of diet and mobility during village formation in the Early Middle Ages: Las Gobas (Burgos,northern Spain)

Strontium, carbon, and nitrogen isotopes of human bone and tooth remains have been used to reconstruct residential mobility and diet of early medieval populations at Las Gobas from the sixth to eleventh centuries. Most non-local individuals correspond to the tenth to eleventh centuries and were mostly women and infants. This residential mobility coincided with the formation of Laño village and the abandonment of artificial cave settlement. Carbon and nitrogen isotope ratios of bone collagen indicate an omnivorous homogenous diet based on terrestrial plant resources, with few animal-derived proteins from livestock. Millet consumption was restricted to an earlier period of time (seventh to ninth centuries); and in later periods (tenth to eleventh centuries), mainly C₃ plants such as wheat and barley were consumed. In general, there were no dietary differences between individuals according to sex or age. Sex-related dietary differences have only been observed in the tenth to eleventh centuries, when females consumed a more vegetarian diet and less animal protein. The higher δ ¹⁵N values in infants reflect the weaning effect, while the differences in δ ¹⁵N values between young adult men and young adult women can be explained as a physiological factor related to pregnancy or different origins. In a comparison with contemporaneous medieval populations in the northern Iberian Peninsula, both δ ¹³C and δ ¹⁵N values suggest similar foodstuff resources and diet among Christian and Muslim populations.     

Paleodietary analysis of the prehistoric population of the Canary Islands inferred from stable isotopes (carbon,nitrogen and hydrogen) in bone collagen

Nitrogen and carbon isotope compositions were measured in the bone collagen from a total of 86 prehispanic samples of the Canary Islands, and hydrogen in 70, all of them with enough amount of bone collagen, and adequate N and C content. These samples belong to prehistoric population of El Hierro (n = 27), Tenerife (n = 18), and Gran Canaria (n = 41). Isotope compositions were also obtained for prehistoric and modern food resources that were likely consumed by these people. Marked differences were observed among the three islands regarding the three isotopes analyzed: the δ¹⁵N values were highest among the population of Gran Canaria (10.8‰ ± 0.9‰), who also showed the highest δD values (7 ± 8‰). The population of El Hierro showed the highest δ¹³C values (−18.6‰ ± 0.7‰). These data suggest a high consumption of marine products by the population from El Hierro, and also an important consumption of terrestrial meat or marine, piscivore fish, by the population from Gran Canaria, together with domesticated C₃ plants (barley and/or wheat), fruits of Ficus carica and other wild species, and goat products. Additionally, marked differences were observed between men and women, which suggest that women consumed a more vegetal-based diet, a finding which is in agreement with the higher proportion of teeth with carious lesions among women.     

Detecting the medieval cod trade: a new method and first results

This paper explores the potential of stable isotope analysis to identify the approximate region of catch of cod by analysing bones from medieval settlements in northern and western Europe. It measures the δ¹³C and δ¹⁵N values of cod bone collagen from medieval control samples collected from sites around Arctic Norway, the North Sea, the Kattegat and the Baltic Sea. These data were considered likely to differ by region due to, for example, variation in the length of the food chain, water temperature and salinity. We find that geographical structuring is indeed evident, making it possible to identify bones from cod caught in distant waters. These results provide a new methodology for studying the growth of long-range trade in dried cod and the related expansion of fishing effort—important aspects of the development of commercialisation in medieval Europe. As a first test of the method, we analyse three collections of cod bones tentatively interpreted as imported dried fish based on a priori zooarchaeological criteria. The results tentatively suggest that cod were being transported or traded over very long distances since the end of the first millennium AD.     

Stable nitrogen isotope values in arid‐land kangaroos correlated with mean annual rainfall: potential as a palaeoclimatic indicator

Bone collagen stable nitrogen isotope values are reported for modern kangaroos (Macropus spp.) from eight field sites along a 1160 km south–north transect from temperate coastal to arid interior South Australia, in order to investigate δ¹⁵N tissue variability in relation to rainfall and relative humidity. Mean annual rainfall along the transect ranges from 775 mm at Mount Gambier in the southeastern coast to 176 mm at Innamincka in the arid northern interior, while 3pm relative humidity ranges from 73% at coastal Flinders Chase to 36% at Innamincka. In arid habitats (176–238 mm rainfall), the δ¹⁵N values of kangaroo bone collagen become more positive in relation to decreasing mean annual rainfall (r² = 0.98), while there is only a weak correlation with relative humidity (r² = 0.67). In contrast, in temperate and semi‐arid coastal habitats (350–775 mm), there is no correlation between kangaroo bone collagen δ¹⁵N values and rainfall (r² = 0.0011) or between δ¹⁵N values and relative humidity (r² = 0.0035). Thus, in South Australia, kangaroo bone collagen δ¹⁵N values do not show a simple linear correlation with either rainfall or relative humidity across all habitats. These results suggest that stable nitrogen isotope analyses of herbivore bones obtained from archaeological and palaeontological sites may provide a reliable proxy for past rainfall values in arid‐land ecosystems. Copyright © 2007 John Wiley & Sons, Ltd.     

Pig diet in medieval York: carbon and nitrogen stable isotopes

This study investigates bone stable isotopes from pigs from medieval York, to characterise the pigs' diet and to explore their contribution to isotopic values from contemporary human bones. Pig bones from the Swinegate (N?=?9) and Coppergate (N?=?14) sites were used for carbon and nitrogen stable isotope analysis to test the hypothesis that the majority of pigs in medieval York were yard-kept and fed on scraps and fish waste, elevating their nitrogen ratios. The results show that the Swinegate and Coppergate pigs gave nitrogen isotope values similar to contemporary sheep and therefore that animal protein made little or no dietary contribution. One sample showed C and N results consistent with more animal protein in the diet, and we propose that this could have been a yard-kept pig consuming human refuse. The majority of the data indicate that the pigs were eating a largely herbivorous diet and that pigs in medieval York may have been raised in rural or woodland locations rather than in the city.     

Isotopic evidence of dietary variability in subadults at the Usu-moshiri site of the Epi-Jomon culture,Japan

This study reconstructs adult and subadult diets of a hunter-gatherer population of the Epi-Jomon culture (approximately 2300–1700 years BP) in Japan, using the stable isotopic analysis of carbon and nitrogen. The results suggest that the Usu-moshiri adults were highly dependent on marine resources such as seals for their dietary protein intake and that no significant dietary differences existed between the sexes. Among subadults we found two types of diet on the basis of different isotopic signatures. One group consisted of individuals with δ¹³C values below than those of the adult female mean minus two standard deviations and δ¹⁵N values lower than those of subadults in the other groups. These low-δ¹³C subadults indicated relatively less enriched δ¹⁵N values by 3.5 years of age at the latest. They probably consumed more ¹³C-depleted foods during weaning than in the ordinary adult diet. In the other high-δ¹³C group, their enriched δ¹⁵N values start to decline by four years of age and fall within the two-standard-deviations range of the total adult mean around five to six years of age. Isotopic values of children in this high-δ¹³C group suggest that they would have been fed ordinary adult diets during weaning. Perinates could also be divided into two groups on the basis of the similar patterns in their carbon and nitrogen isotope ratios. Our results indicate variabilities in the diets of subadults, and similar variabilities were also seen in ethnographic studies of the Ainu populations.     

Aquatic resources in human diet in the Late Mesolithic in Northern France and Luxembourg: insights from carbon,nitrogen and sulphur isotope ratios

We investigated the contribution of freshwater resources to the diet of seven Late Mesolithic hunter-gatherers (ca. 5300–7000 BC) from Northern France and Luxembourg using stable isotope ratios. In addition to the carbon and nitrogen stable isotope ratios (δ¹³C, δ¹⁵N), we explored the potential of the sulphur isotopic ratios (δ³⁴S) to detect and quantify the proportion of protein derived from aquatic foodstuff. In only two sites, animal remains from an associated settlement were available and subsequently examined to decipher the isotopic differential between terrestrial and freshwater resources. The quantification of their relative contribution was simulated using a Bayesian mixing model. The measurements revealed a significant overlap in δ¹³C values between freshwater and terrestrial resources and a large range of δ¹⁵N values for each food category. The δ³⁴S values of the aquatic and terrestrial animals were clearly distinct at the settlement in the Seine valley, while the results on fish from Belgium demonstrated a possible overlap in δ³⁴S values between freshwater and terrestrial resources. Local freshwater ecosystem likely contributed to ca. 30–40 % of the protein in the diet of the individuals found in the Seine settlement. Out of this context, the isotopic signature and thus contribution of the available aquatic foods was difficult to assess. Another potential source of dietary protein is wild boar. Depending on the local context, collagen δ³⁴S values may contribute to better assessment of the relative contribution of freshwater and terrestrial resources.     

BIOARCHAEOLOGICAL ANALYSIS OF SUBSISTENCE AND HEALTH AT THE LAKE GEORGE SITE,MISSISSIPPI (22YZ557)

Abstract

Bioarchaeological investigations of subsistence and health were conducted on a skeletal population from the Lake George site (22YZ557), a large prehistoric settlement in the lower Yazoo basin of west-central Mississippi. Subsistence is inferred from oral health indicators (including dental caries, calculus, periodontal disease, abscesses, antemortem tooth loss, and macrowear) and stable carbon and nitrogen isotope ratios from bone collagen and apatite. Health is inferred from nonspecific indicators (including cranial porous lesions, enamel hypoplasias, and Harris lines). The sample includes 25 adults and 25 subadults, all of which date to the Coles Creek period (A.D. 700–1200). Frequencies of all pathological conditions are reported for the entire sample and divided by sex and age for adults. Results indicate a heavy pathology load at Lake George, but one that is not dissimilar to other Coles Creek populations. Isotope values indicate a diet that included primarily C3 plants (δ¹³C_Col = ?21.03‰, δ¹³C_Ap-Diet = ?22.06) and terrestrial protein (δ¹⁵N = 9.72‰). The sources of nonspecific pathologies are attributed to stressors associated with increasing population density and cultural complexity that occurred during the Coles Creek period.