The Ice Man's diet as reflected by the stable nitrogen and carbon isotopic composition of his hair.

Establishing the diets of ancient human populations is an integral component of most archaeological studies. Stable isotope analysis of well-preserved bone collagen is the most direct approach for a general assessment of paleodiet. However, this method has been limited by the scarcity of well-preserved skeletal materials for this type of destructive analysis. Hair is preserved in many burials, but is often overlooked as an alternative material for isotopic analysis. Here we report that the stable carbon and nitrogen isotope values for the hair of the 5200 year-old Ice Man indicates a primarily vegetarian diet, in agreement with his dental wear pattern. Whereas previous investigations have focused on bone collagen, the stable isotope composition of hair may prove to be a more reliable proxy for paleodiet reconstruction, particularly when skeletal remains are not well preserved and additional archaeological artifacts are unavailable.     

Investigations into the effect of diet on modern human hair isotopic values

Carbon and nitrogen isotopic analysis of body tissues is one of the few techniques that can furnish quantitative information about the diet of archaeological humans. The study of the effects of various diets on modern human isotopic values can help to refine palaeodietary theories, and such work also enables the testing of palaeodietary theories independent of archaeological remains and interpretations. This report discusses the use of modern human hair as a sample material for isotopic analysis. The biogenic carbon and nitrogen isotopic signal is well preserved in hair, and the isotopic values of the keratin can be related to diet. We show that atmospheric and cosmetic contamination of hair keratin does not appear to affect the measured isotopic values. In a small study of Oxford residents, we demonstrate that the magnitude of the nitrogen isotopic values of hair keratin reflects the proportion of animal protein consumed in the diet: omnivores and ovo-lacto-vegetarians have higher delta15N than vegans. There was an observed relationship between the reported amount of animal protein eaten (either meat or secondary animal products) and the nitrogen isotopic values within the two groups of omnivores and ovo-lacto-vegetarians, indicating that an increasing amount of animal protein in the diet results in an increase in the delta15N of hair keratin. This provides the first independent support for a long-held theory that, for individuals within a single population, a diet high in meat equates to elevated nitrogen isotopic values in the body relative to others eating less animal protein. The implications of such results for the magnitude of the trophic level effect are discussed. Results presented here also permit a consideration of the effects of a change of diet in the short and long term on hair keratin isotopic values.     

The confounding effects of source isotopic heterogeneity on consumer–diet and tissue–tissue stable isotope relationships

Stable isotope analysis of consumer tissues document patterns of resource use because data are linearly related to isotope compositions of their source(s) (i.e., food, water, etc.). Deviations in parameters estimated for these relationships can arise from variations in consumer tissue-diet spacing (Δ(TS)) and the level of isotopic heterogeneity in the source(s). We present a set of simple hypotheses that distinguish between the effects of Δ(TS) and source isotope heterogeneity. The latter may arise via mixed diets, during tissue turnover, or by isotopic routing of dietary components. We apply these concepts to stable carbon and nitrogen isotope relationships between gut contents and body tissues of large mammal herbivores from mixed C(3)/C(4) South African savannas and test predictions based on the compound- and/or time-specific data archived within each material. Predicted effects of source isotope heterogeneity are readily detected in carbon isotope relationships between materials representing different time periods or comprising bulk versus protein-only diet components. Differences in Δ(TS) of carbon isotopes across mammal herbivore species with very different feeding niches (and diet isotope compositions) are likely to be small or non-existent in these habitats. Variations in Δ(TS) estimated for nitrogen isotopes are much greater, leading to inconsistencies that cannot be explained by diet or trophic level effects alone. The effects of source heterogeneity on isotopic relationships generate numerical artefacts that have been misinterpreted as variations in Δ(TS). We caution against generalized application of hypotheses based on assumptions of source isotopic homogeneity, even for single diets commonly used in laboratory studies. More careful consideration of how heterogeneity affects consumer-diet relationships is needed for many field and laboratory systems.     

Protein Retention Assessment of Four Levels of Poultry By-Product Substitution of Fishmeal in Rainbow Trout (Oncorhynchus mykiss) Diets Using Stable Isotopes of Nitrogen (δ15N) as Natural Tracers

This is second part from an experiment where the nitrogen retention of poultry by-product meal (PBM) compared to fishmeal (FM) was evaluated using traditional indices. Here a quantitative method using stable isotope ratios of nitrogen (δ¹⁵N values) as natural tracers of nitrogen incorporation into fish biomass is assessed. Juvenile rainbow trout (Oncorhynchus mykiss) were fed for 80 days on isotopically distinct diets in which 0, 33, 66 and 100% of FM as main protein source was replaced by PBM. The diets were isonitrogenous, isolipidic and similar in gross energy content. Fish in all treatments reached isotopic equilibrium by the end of the experiment. Two-source isotope mixing models that incorporated the isotopic composition of FM and PBM as well as that of formulated feeds, empirically derived trophic discrimination factors and the isotopic composition of fish that had reached isotopic equilibrium to the diets were used to obtain a quantitative estimate of the retention of each source of nitrogen. Fish fed the diets with 33 and 66% replacement of FM by PBM retained poultry by-product meal roughly in proportion to its level of inclusion in the diets, whereas no differences were detected in the protein efficiency ratio. Coupled with the similar biomass gain of fishes fed the different diets, our results support the inclusion of PBM as replacement for fishmeal in aquaculture feeds. A re-feeding experiment in which all fish were fed a diet of 100% FM for 28 days indicated isotopic turnover occurred very fast, providing further support for the potential of isotopic ratios as tracers of the retention of specific protein sources into fish tissues. Stable isotope analysis is a useful tool for studies that seek to obtain quantitative estimates of the retention of different protein sources.     

Exploring the Potential of Laser Ablation Carbon Isotope Analysis for Examining Ecology during the Ontogeny of Middle Pleistocene Hominins from Sima de los Huesos (Northern Spain)

Laser ablation of tooth enamel was used to analyze stable carbon isotope compositions of teeth of hominins, red deer, and bears from middle Pleistocene sites in the Sierra de Atapuerca in northern Spain, to investigate the possibility that this technique could be used as an additional tool to identify periods of physiological change that are not detectable as changes in tooth morphology. Most of the specimens were found to have minimal intra-tooth variation in carbon isotopes (< 2.3‰), suggesting isotopically uniform diets through time and revealing no obvious periods of physiological change. However, one of the two sampled hominin teeth displayed a temporal carbon isotope shift (3.2‰) that was significantly greater than observed for co-occurring specimens. The δ¹³C value of this individual averaged about -16‰ early in life, and -13‰ later in life. This isotopic change occurred on the canine crown about 4.2 mm from the root, which corresponds to an approximate age of two to four years old in modern humans. Our dataset is perforce small owing to the precious nature of hominid teeth, but it demonstrates the potential utility of the intra-tooth isotope profile method for extracting ontogenetic histories of human ancestors.     

Integrating stomach content and stable isotope analyses to quantify the diets of pygoscelid penguins

Stomach content analysis (SCA) and more recently stable isotope analysis (SIA) integrated with isotopic mixing models have become common methods for dietary studies and provide insight into the foraging ecology of seabirds. However, both methods have drawbacks and biases that may result in difficulties in quantifying inter-annual and species-specific differences in diets. We used these two methods to simultaneously quantify the chick-rearing diet of Chinstrap (Pygoscelis antarctica) and Gentoo (P. papua) penguins and highlight methods of integrating SCA data to increase accuracy of diet composition estimates using SIA. SCA biomass estimates were highly variable and underestimated the importance of soft-bodied prey such as fish. Two-source, isotopic mixing model predictions were less variable and identified inter-annual and species-specific differences in the relative amounts of fish and krill in penguin diets not readily apparent using SCA. In contrast, multi-source isotopic mixing models had difficulty estimating the dietary contribution of fish species occupying similar trophic levels without refinement using SCA-derived otolith data. Overall, our ability to track inter-annual and species-specific differences in penguin diets using SIA was enhanced by integrating SCA data to isotopic mixing modes in three ways: 1) selecting appropriate prey sources, 2) weighting combinations of isotopically similar prey in two-source mixing models and 3) refining predicted contributions of isotopically similar prey in multi-source models.     

Sexual differences in the foraging ecology of 19th century beluga whales (Delphinapterus leucas) from the Canadian High Arctic

Marine mammals often exhibit significant sexual segregation in their diet and habitat use but these differences have not been studied systematically in historic or ancient populations due to the difficulties associated with determining the sex of skeletal elements based on gross morphology. Using a combined ancient DNA and stable isotope approach, we document a sexual difference in the foraging ecology of late 19th century beluga whales (Delphinapterus leucas) from the Canadian High Arctic. Using two PCR assays that coamplify fragments of the Y-linked SRY and X-linked ZFX genes, we assigned reproducible sex identities to 35 beluga specimens. This provided a basis for investigating sex-specific differences in foraging ecology using stable carbon and nitrogen isotope analyses of bone collagen. These isotopic data demonstrate that although both males and females primarily consumed Arctic cod, males utilized a wider range of prey than females, feeding on high trophic level benthic prey (sculpins) to a greater extent. Because bone collagen integrates prey isotopic compositions over the course of several years these sex-based differences in beluga bone collagen isotopic compositions reflect long-term and sustained sexual differences in foraging.     

The diet‐body offset in human nitrogen isotopic values: A controlled dietary study

The “trophic level enrichment” between diet and body results in an overall increase in nitrogen isotopic values as the food chain is ascended. Quantifying the diet–body Δ¹⁵N spacing has proved difficult, particularly for humans. The value is usually assumed to be +3–5‰ in the archaeological literature. We report here the first (to our knowledge) data from humans on isotopically known diets, comparing dietary intake and a body tissue sample, that of red blood cells. Samples were taken from 11 subjects on controlled diets for a 30‐day period, where the controlled diets were designed to match each individual's habitual diet, thus reducing problems with short‐term changes in diet causing isotopic changes in the body pool. The Δ¹⁵N_diet‐RBC was measured as +3.5‰. Using measured offsets from other studies, we estimate the human Δ¹⁵N_{diet‐keratin} as +5.0–5.3‰, which is in good agreement with values derived from the two other studies using individual diet records. We also estimate a value for Δ¹⁵N_{diet‐collagen} of ≈6‰, again in combination with measured offsets from other studies. This value is larger than usually assumed in palaeodietary studies, which suggests that the proportion of animal protein in prehistoric human diet may have often been overestimated in isotopic studies of palaeodiet. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.     

Effects of food quality on tissue-specific isotope ratios in the mussel <Emphasis Type="Italic">Perna perna</Emphasis>

Investigations into trophic ecology and aquatic food web resolution are increasingly accomplished through stable isotope analysis. The incorporation of dietary and metabolic changes over time results in variations in isotope signatures and turnover rates of producers and consumers at tissue, individual, population and species levels. Consequently, the elucidation of trophic relationships in aquatic systems depends on establishing standard isotope values and tissue turnover rates for the level in question. This study investigated the effect of diet and food quality on isotopic signatures of four mussel tissues: adductor muscle, gonad, gill and mantle tissue from the brown mussel Perna perna. In the laboratory, mussels were fed one of the two isotopically distinct diets for 3 months. Although not all results were significant, overall δ¹³C ratios in adductor, mantle and gill tissues gradually approached food source signatures in both diets. PERMANOVA analyses revealed significant changes over time in tissue δ¹³C (mantle and gill) with both diets and in δ¹⁵N (all tissues) and C:N ratios (mantle and gill) for one diet only. The percentage of replaced carbon isotopes were calculated for the 3 month period and differed among tissues and between diets. The tissue with the highest and lowest amount of replaced isotopes over 81 days were mantle tissue on the kelp diet (33.89%) and adductor tissue on the fish food diet (4.14%), respectively. Percentages could not be calculated for any tissue in either diet for δ¹⁵N due to the lack of significant change in tissue nitrogen. Fractionation patterns in tissues for both diets can be linked to nutritional stress, suggesting that consumer isotopic signatures are strongly dependent on food quality, which can significantly affect the degree of isotopic enrichment within a trophic level.     

Geographical patterns of human diet derived from stable-isotope analysis of fingernails

Carbon and nitrogen isotope ratios of human fingernails were measured in 490 individuals in the western US and 273 individuals in southeastern Brazil living in urban areas, and 53 individuals living in a moderately isolated area in the central Amazon region of Brazil and consuming mostly locally grown foods. In addition, we measured the carbon and nitrogen isotope ratios of common food items to assess the extent to which these isotopic signatures remain distinct for people eating both omnivorous and vegetarian diets and living in different parts of the world, and the extent to which dietary information can be interpreted from these analyses. Fingernail delta13C values (mean +/- standard deviation) were -15.4 +/- 1.0 and -18.8 +/- 0.8 per thousand and delta15N values were 10.4 +/- 0.7 and 9.4 +/- 0.6 per thousand for southeastern Brazil and western US populations, respectively. Despite opportunities for a "global supermarket" effect to swamp out carbon and nitrogen isotope ratios in these two urbanized regions of the world, differences in the fingernail isotope ratios between southeastern Brazil and western US populations persisted, and appeared to be more associated with regional agricultural and animal production practices. Omnivores and vegetarians from Brazil and the US were isotopically distinct, both within and between regions. In a comparison of fingernails of individuals from an urban city and isolated communities in the Amazonian region, the urban region was similar to southeastern Brazil, whereas individuals from isolated nonurban communities showed distinctive isotopic values consistent with their diets and with the isotopic values of local foods. Although there is a tendency for a "global supermarket" diet, carbon and nitrogen isotopes of human fingernails hold dietary information directly related to both food sources and dietary practices in a region.     

Stable isotope analysis of modern human hair collected from Asia (China,India, Mongolia,and Pakistan)

We report isotopic data (δ²H, δ¹⁸O n = 196; δ¹³C, δ¹⁵N n = 142; δ³⁴S n = 85) from human hair and drinking water (δ²H, δ¹⁸O n = 67) collected across China, India, Mongolia, and Pakistan. Hair isotope ratios reflected the large environmental isotopic gradients and dietary differences. Geographic information was recorded in H and O and to a lesser extent, S isotopes. H and O data were entered into a recently developed model describing the relationship between the H and O isotope composition of human hair and drinking water in modern USA and pre‐globalized populations. This has anthropological and forensic applications including reconstructing environment and diet in modern and ancient human hair. However, it has not been applied to a modern population outside of the USA, where we expect different diet. Relationships between H and O isotope ratios in drinking water and hair of modern human populations in Asia were different to both modern USA and pre‐globalized populations. However, the Asian dataset was closer to the modern USA than to pre‐globalized populations. Model parameters suggested slightly higher consumption of locally producedfoods in our sampled population than modern USA residents, but lower than pre‐globalized populations. The degree of in vivo amino acid synthesis was comparable to both the modern USA and pre‐globalized populations. C isotope ratios reflected the predominantly C₃‐based regional agriculture and C₄ consumption in northernChina. C, N, and S isotope ratios supported marine food consumption in some coastal locales. N isotope ratios suggested a relatively low consumption of animal‐derived products compared to western populations. Am J Phys Anthropol 2010. © 2009 Wiley‐Liss, Inc.     

Effects of elemental composition on the incorporation of dietary nitrogen and carbon isotopic signatures in an omnivorous songbird

The use of stable isotopes to infer diet requires quantifying the relationship between diet and tissues and, in particular, knowing of how quickly isotopes turnover in different tissues and how isotopic concentrations of different food components change (discriminate) when incorporated into consumer tissues. We used feeding trials with wild-caught yellow-rumped warblers (Dendroica coronata) to determine delta15N and delta13C turnover rates for blood, delta15N and delta13C diet-tissue discrimination factors, and diet-tissue relationships for blood and feathers. After 3 weeks on a common diet, 36 warblers were assigned to one of four diets differing in the relative proportion of fruit and insects. Plasma half-life estimates ranged from 0.4 to 0.7 days for delta13C and from 0.5 to 1.7 days for delta15N . Half-life did not differ among diets. Whole blood half-life for delta13C ranged from 3.9 to 6.1 days. Yellow-rumped warbler tissues were enriched relative to diet by 1.7-3.6% for nitrogen isotopes and by -1.2 to 4.3% for carbon isotopes, depending on tissue and diet. Consistent with previous studies, feathers were the most enriched and whole blood and plasma were the least enriched or, in the case of carbon, slightly depleted relative to diet. In general, tissues were more enriched relative to diet for birds on diets with high percentages of insects. For all tissues, carbon and nitrogen isotope discrimination factors increased with carbon and nitrogen concentrations of diets. The isotopic signature of plasma increased linearly with the sum of the isotopic signature of the diet and the discrimination factor. Because the isotopic signature of tissues depends on both elemental concentration and isotopic signature of the diet, attempts to reconstruct diet from stable isotope signatures require use of mixing models that incorporate elemental concentration.     

A food web analysis of the juvenile blue crab, Callinectes sapidus, using stable isotopes in whole animals and individual amino acids

The stable isotope compositions (C and N) of plants and animals of a marsh dominated by Spartina alterniflora in the Delaware Estuary were determined. The study focused on the juvenile stage of the Atlantic blue crab, Callinectes sapidus, and the importance of marsh-derived diets in supporting growth during this stage. Laboratory growth experiments and field data indicated that early juvenile blue crabs living in the Delaware Bay habitat fed primarily on zooplankton, while marsh-dwelling crabs, which were enriched in ¹³C relative to bay juveniles, utilized marsh-derived carbon for growth. In laboratory experiments, the degree to which juvenile blue crabs isotopically fractionated dietary nitrogen, as well as the growth rate, depended on the protein quality of the diet. The range of δ¹³C of amino acids in laboratory-reared crabs and their diets was almost 20‰, similar to the isotopic range of amino acids of other organisms. In laboratory studies, the δ¹³C of nonessential and essential amino acids in the diet were compared to those in juvenile crabs. Isotopic fractionation at the molecular level depended on diet quality and the crabs' physiological requirements. Comparison of whole-animal isotope data with individual amino acid C isotope measurements of wild juvenile blue crabs from the bay and marsh suggested a different source of total dietary carbon, yet a shared protein component, such as zooplankton. Received: 1 July 1998 / Accepted: 15 March 1999     

Hydrogen and oxygen isotope ratios in body water and hair: modeling isotope dynamics in nonhuman primates

The stable isotopic composition of drinking water, diet, and atmospheric oxygen influence the isotopic composition of body water ((2)H/(1)H, (18)O/(16)O expressed as δ(2) H and δ(18)O). In turn, body water influences the isotopic composition of organic matter in tissues, such as hair and teeth, which are often used to reconstruct historical dietary and movement patterns of animals and humans. Here, we used a nonhuman primate system (Macaca fascicularis) to test the robustness of two different mechanistic stable isotope models: a model to predict the δ(2)H and δ(18)O values of body water and a second model to predict the δ(2)H and δ(18)O values of hair. In contrast to previous human-based studies, use of nonhuman primates fed controlled diets allowed us to further constrain model parameter values and evaluate model predictions. Both models reliably predicted the δ(2)H and δ(18)O values of body water and of hair. Moreover, the isotope data allowed us to better quantify values for two critical variables in the models: the δ(2)H and δ(18)O values of gut water and the (18)O isotope fractionation associated with a carbonyl oxygen-water interaction in the gut (α(ow)). Our modeling efforts indicated that better predictions for body water and hair isotope values were achieved by making the isotopic composition of gut water approached that of body water. Additionally, the value of α(ow) was 1.0164, in close agreement with the only other previously measured observation (microbial spore cell walls), suggesting robustness of this fractionation factor across different biological systems.     

Back to the future? Late Holocene marine food web structure in a warm climatic phase as a predictor of trophodynamics in a warmer South‐Western Atlantic Ocean

Stable carbon and nitrogen isotope ratios in the skeletal elements of both ancient and modern marine species from the Beagle Channel were used to compare the structure of Late Holocene and modern food webs, and predict potential changes as a result of a Sea Surface Temperature (SST) increase in the region. Complementary, ancient and modern shells of limpets and mussels were isotopically analysed to explore changes in the isotopic baseline and compare marine food webs through time after an appropriate correction for baseline shifts. Results confirmed a declining pattern of marine primary productivity during the Late Holocene in the Beagle Channel. In general, the isotopic niches overlapped largely in the ancient food web in comparison to the current marine one, with the exception of that of cormorants (Phalacrocorax sp.). Our data suggest that all the species that have undergone intense human exploitation (Arctocephalus australis, Otaria flavescens and Merluccius sp.) significantly increased their trophic levels. The most important finding of this work was the very high isotopic overlap between snoek (Thyrsites atun) and hake (Merluccius sp.) during the Late Holocene. Increasing SST as a result of global warming could favour the recolonization of the southern South‐Western Atlantic Ocean by snoek from the South‐Eastern Pacific Ocean, with a potential impact on the landings of the economically important Argentine and Austral hake. These findings highlight the relevance of using zooarchaeological remains for providing predictions about marine food webs changes in the near future.     

Isotopic Discrimination in the Double-Crested Cormorant (Phalacrocorax auritus)

The diet-tissue discrimination factor is the amount by which a consumer’s tissue varies isotopically from its diet, and is therefore a key element in models that use stable isotopes to estimate diet composition. In this study we measured discrimination factors in blood (whole blood, red blood cells and plasma), liver, muscle and feathers of Double-crested Cormorants (Phalacrocorax auritus) for stable isotope ratios of carbon, nitrogen and sulfur. Cormorants exhibited discrimination factors that differed significantly among tissue types (for carbon and nitrogen), and differed substantially (in the context of the isotopic variation among relevant prey species) from those observed in congeneric species. The Double-crested Cormorant has undergone rapid population expansion throughout much of its historic range over the past three decades, leading to both real and perceived conflicts with fisheries throughout North America, and this study provides an essential link for the use of stable isotope analysis in researching foraging ecology, diet, and resource use of this widespread and controversial species.     

Dietary and physiological controls on the hydrogen and oxygen isotope ratios of hair from mid‐20th century indigenous populations

A semimechanistic model has recently been proposed to explain observed correlations between the H and O isotopic composition of hair from modern residents of the USA and the isotopic composition of drinking water, but the applicability of this model to hair from non‐USA and preglobalization populations is unknown. Here we test the model against data from hair samples collected during the 1930s–1950s from populations of five continents. Although C and N isotopes confirm that the samples represent a much larger range of dietary “space” than the modern USA residents, the model is able to reproduce the observed δ²H and δ¹⁸O values given reasonable adjustments to 2 model parameters: the fraction of dietary intake derived from locally produced foods and the fraction of keratin H fixed during the in vivo synthesis of amino acids. The model is most sensitive to the local dietary intake, which appears to constitute between 60% and 80% of diet among the groups sampled. The isotopic data are consistent with a trophic‐level effect on protein H isotopes, which we suggest primarily reflects mixing of ²H‐enriched water and ²H‐depleted food H in the body rather than fractionation during biosynthesis. Samples from Inuit groups suggest that humans with marine‐dominated diets can be identified on the basis of coupled δ²H and δ¹⁸O values of hair. These results indicate a dual role for H and O isotopic measurements of keratin, including both biological (diet, physiology) and environmental (geographic movement, paleoclimate) reconstruction. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

King eiders use an income strategy for egg production: a case study for incorporating individual dietary variation into nutrient allocation research

The use of stored nutrients for reproduction represents an important component of life-history variation. Recent studies from several species have used stable isotopes to estimate the reliance on stored body reserves in reproduction. Such approaches rely on population-level dietary endpoints to characterize stored reserves (“capital”) and current diet (“income”). Individual variation in diet choice has so far not been incorporated in such approaches, but is crucial for assessing variation in nutrient allocation strategies. We investigated nutrient allocation to egg production in a large-bodied sea duck in northern Alaska, the king eider (Somateria spectabilis). We first used Bayesian isotopic mixing models to quantify at the population level the amount of endogenous carbon and nitrogen invested into egg proteins based on carbon and nitrogen isotope ratios. We then defined the isotopic signature of the current diet of every nesting female based on isotope ratios of eggshell membranes, because diets varied isotopically among individual king eiders on breeding grounds. We used these individual-based dietary isotope signals to characterize nutrient allocation for each female in the study population. At the population level, the Bayesian and the individual-based approaches yielded identical results, and showed that king eiders used an income strategy for the synthesis of egg proteins. The majority of the carbon and nitrogen in albumen (C: 86 ± 18%, N: 99 ± 1%) and the nitrogen in lipid-free yolk (90 ± 15%) were derived from food consumed on breeding grounds. Carbon in lipid-free yolk derived evenly from endogenous sources and current diet (exogenous C: 54 ± 24%), but source contribution was highly variable among individual females. These results suggest that even large-bodied birds traditionally viewed as capital breeders use exogenous nutrients for reproduction. We recommend that investigations of nutrient allocation should incorporate individual variation into mixing models to reveal intraspecific variation in reproductive strategies.     

Using stable isotope analysis to obtain dietary profiles from old hair: a case study from Plains Indians

Stable isotope composition of human tissue reflects that of foods consumed, and can provide information about diet independent of artifactual remains. Here we refine and test this method by analyzing nitrogen (delta(15)N) and carbon (delta(13)C) isotope ratios in historic North American Plains Indians hair. Gas-source isotope-ratio mass spectrometry provides high-precision data for both delta(15)N and delta(13)C (+/-0.2 per thousand, 1 sigma) in single hair strands as short as 2 cm (100-150 mug). Because hair contains more carbon than nitrogen, if only delta(13)C data are needed, shorter strands (<1 cm) can be analyzed. This reduction in sample size opens new opportunities for analysis of small hair fragments found in archaeological excavations, as well as for analysis of seasonal variations in long hair strands. We find distinct isotope profiles (delta(15)N vs. delta(13)C) for two cultural groups, the Lower Brule reservation Sioux of 1892 and the reservation Blackfoot of 1892 and 1935. The resultant dietary profiles indicate a higher consumption of meat by the Blackfoot and a higher consumption of maize (or of animals that had fed on maize or other C(4) plants) by the Lower Brule. The two groups of Blackfoot yield similar isotopic profiles despite the passage of four decades, suggesting a strong role for cultural preference even as food sources change. Such stable isotope profiles can be used to link samples from the same cultural tradition based on their similar diets.     

内蒙古巴彦淖尔市纳林套海汉墓出土人骨的稳定同位素分析

稳定同位素分析技术近年来发展为复原古代民族食物结构、社会经济模式的有效手段。本文应用该技术对内蒙古自治区纳林套海汉代墓葬出土人骨中的C、N同位素比值进行了测定。结果表明, 纳林套海汉代居民日常饮食结构中保持着非常高的动物性食物摄入, 植物类食物的摄入中以C4类植物为主。结合其他相关研究结果, 我们认为西汉王朝通过实施移民屯垦和属国等政策, 大力推动了河套地区的农业和畜牧业生产, 改变了河套地区原有的经济模式和人们的饮食结构。本文的研究结果可以为复原汉代北部边疆的经济模式研究提供有益的线索和证据。