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In recent years, it has become evident that limitations exist in our ability to meaningfully assess palaeodiet using stable isotope compositions. These limitations in part arise because many of the fundamental assumptions about tissue-diet relationships are poorly understood. In order to redress this deficiency, a controlled feeding experiment was undertaken to define the impact of terrestrial- vs. marine-derived dietary protein consumption on consumer tissue carbon isotopic compositions (δ13C). Two generations of pigs were raised on one of five feeds with varying proportions of terrestrial (soy) and marine (fish meal) protein. A comprehensive range of tissues and fluids from 49 pigs was submitted for δ13C analysis. The observed tissue–whole diet and tissue–dietary protein carbon isotopic offsets were found to be highly dependent on the percentage of marine protein in diet. We suggest that the trend in δ13C offsets most likely derives from the increased routing of non-essential amino acids, especially glycine, with the increasing proportion of marine protein in the diet. These findings demonstrate that solely using bulk δ13C compositions not only masks considerable information about diet, but may also lead to erroneous representations of marine and terrestrial resource consumption in the past.

Compound-specific amino acid carbon-isotope compositions have shown particular promise for elucidating dietary behaviors in complex environmental contexts, and may also be able to mitigate the effect of many of the limitations inherent to palaeodietary reconstructions. Here, we investigate the efficacy of compound-specific amino acid isotopic proxies in characterizing the consumption of different dietary protein sources using amino acid carbon-isotope compositions for humans and fauna from Rössberga (Early to Middle Neolithic), Köpingsvik (Mesolithic and Middle Neolithic), and Visby (Medieval Period), Sweden. We also assess the explanatory capabilities of an isotopic mixing model when used with essential amino acid carbon-isotope compositions of humans and local fauna. All three isotopic proxies distinguished among humans from the three sites consistently and informatively, and were able to enhance the broad interpretations made using bulk isotopic compositions. The mixing model palaeodietary reconstruction revealed considerable diversity in relative protein source contributions among individuals at both Köpingsvik and Visby. Comparing the mixing model for bulk carbon- and nitrogen-isotope compositions to the model for essential amino acid isotopic compositions further demonstrated the likelihood of underestimation and overestimation of marine protein consumption for both aquatic-dominant and mixed marine-terrestrial diets when using bulk isotopic compositions.

Of central importance to palaeodietary reconstruction is a clear understanding of relative contributions of different terrestrial (i.e., C3 vs. C4 plants) and aquatic (i.e., freshwater vs. marine) resources to human diet. There are, however, significant limitations associated with the ability to reconstruct palaeodiet using bulk collagen stable isotope compositions in regions where diverse dietary resources are available. Recent research has determined that carbon-isotope analysis of individual amino acids has considerable potential to elucidate dietary protein source where bulk isotopic compositions cannot. Using δ13CAA values for human and faunal remains from Zvejnieki, Latvia (8th – 3rd millennia BCE), we test several isotopic proxies focused on distinguishing freshwater protein consumption from both plant-derived and marine protein consumption. We determined that the Δ13CGly-Phe and Δ13CVal-Phe proxies can effectively discriminate between terrestrial and aquatic resource consumption, and the relationship between essential δ13CAA values and the Δ13CGly-Phe and Δ13CVal-Phe proxies can differentiate among the four protein consumption groups tested here. Compound-specific amino acid carbon-isotope dietary proxies thus enable an enhanced understanding of diet and resource exploitation in the past, and can elucidate complex dietary behaviour.

Stable isotope analysis and AMS dating of human and animal bone from the Bulgarian Black Sea coastal sites of Varna I and Durankulak provide fascinating insights into their spatial development as Neolithic and Aeneolithic (Copper Age/Chalcolithic) cemeteries, their associated chronologies, and the dietary signatures of the individuals buried there. The question of the Black Sea reservoir effect is explored, together with a comparison of dietary signatures with other European populations. The isotopic results suggest the populations of Varna and Durankulak primarily utilised C3, terrestrial--based protein sources, despite their presumed proximity to the Black Sea. No significant correlation was found between the isotopic signatures and the material wealth of individuals at Varna, which may have implications for theories regarding emergent social/economic hierarchies in prehistory. The AMS results suggest the Varna I cemetery was utilised for a short period of 70–155 years (±1σ) in the middle of the fifth millennium BC. Although only a small proportion of the Durankulak burials was dated, evidence suggests the cemetery was in use for at least half a millennium and burials had likely ceased by 4450 BC, in the early part of the Late Aeneolithic, at approximately the same time as those at Varna I. The implications of the AMS dates are discussed in relation to the development of a Black Sea innovation centre in ceramics and metallurgy and the diffusion of these innovations to other parts of the Balkans and the north Pontic zone. Critical issues are identified for Early and Middle Aeneolithic chronology with respect to the dating sequence of the Durankulak cemetery.

We present bone collagen amino acid (AA) δ13C values for a range of archaeological samples representing four “benchmark” human diet groups (high marine protein consumers, high freshwater protein consumers, terrestrial C3 consumers, and terrestrial C4 consumers), a human population with an “unknown” diet, and ruminants. The aim is to establish an interpretive palaeodietary framework for bone collagen AA δ13C values, and to assess the extent to which AA δ13C values can provide additional dietary information to bulk collagen stable isotope analysis. Results are analyzed to determine the ability of those AAs for which we have a complete set, to discriminate between the diet groups. We show that very strong statistical discrimination is obtained for all interdiet group comparisons. This is often obvious from suitably chosen bivariate plots using δ113C values that have been normalized to compensate for interdiet group differences in bulk δ13C values. Bi-plots of non-normalized phenylalanine and valine δ13C values are useful for distinguishing aquatic diets (marine and freshwater) from terrestrial diets. Our interpretive framework uses multivariate statistics (e.g., discriminant analysis) to optimize the separation of the AA δ13C values of the “benchmark”’ diet groups, and is capable of accurately assigning external samples to their expected diet groups. With a growing body of AA δ13C values, this method is likely to enhance palaeodietary research by allowing the “unknown” diets of populations under investigation to be statistically defined relative to the well-characterized or “known” diets of previously investigated populations. Am J Phys Anthropol 2012. © 2012 Wiley Periodicals, Inc.

The relative contribution of marine-derived carbon in the ancient diet is essential for correcting the marine reservoir effect on the radiocarbon age of archaeological human remains. In this study, we evaluated the marine protein consumption of 3 human populations from the Okhotsk culture (about AD 550–1200) in Hokkaido, Japan, based on stable carbon and nitrogen isotopic compositions in bulk bone collagen as well as the nitrogen isotopic composition of glutamic acid and phenylalanine. Despite the similarity of carbon and nitrogen isotopic composition of bulk collagens, nitrogen isotopic composition of their constituent amino acids suggests differences in fur seal contributions among northern Hokkaido (0–24% for Kafukai 1, 0–10% for Hamanaka 2) and eastern Hokkaido (78–80% for Moyoro) populations. It suggests that nitrogen composition of glutamic acid and phenylalanine could provide a detailed picture of ancient human subsistence.

The research team of this new project has begun the precision radiocarbon dating of the super-important Copper Age cemetery at Varna. These first dates show the cemetery in use from 4560-4450 BC, with the possibility that the richer burials are earlier and the poor burials later in the sequence. The limited number of lavish graves at Varna, representing no more than a handful of paramount chiefs, buried over 50-60 years, suggests a stabilisation of the new social structure by the early part of the Late Copper Age.

Stable isotope analyses have been applied to human and faunal bone collagen from the Varna I and Durankulak cemeteries to explore palaeodietary adaptations in the Neolithic and Eneolithic (Copper Age). The results suggest both populations primarily utilised terrestrial, C 3 -based diets, despite their proximity to the Black Sea. The wider δ 15 N range of the Durankulak humans likely indicates the differential utilisation of terrestrial meat sources, which is probably related to the degree to which primary and/or secondary ovicaprid products were consumed, particularly since ovicaprid δ 15 N values differ from other herbivores. The isotopic distribution of Varna I reflects a linear relationship between δ 15 N and δ 13 C, suggesting that a minority of individuals enriched in both isotopic parameters supplemented their diets with marine resources. These burials include the well known ‘chieftain’ (burial 43) and show notable material wealth by way of grave goods. At the population level, however, there is no significant correlation between stable isotope values and material wealth at Varna I, a fact with implications for theories regarding emergent social/economic hierarchies in Balkan prehistory. Five burials at Durankulak were found to have relatively enriched δ 13 C and δ 15 N values with respect to the rest of the population. These burials reflect a prominently marine-based or mixed terrestrial C 3 -based diet that included C 4 inputs, possibly from millet, for which the limitations of stable isotope analysis on bulk collagen are not able to differentiate. AMS dating has shown that these burials belong to a much later period.

In this article we outline some of the key characteristics of the social structure of the Climax Copper Age in the eastern Balkans and the contributions of the Varna cemetery to those developments. We continue by examining the implications of the new series of 21 AMS dates from the Oxford Radiocarbon Laboratory, which represent the first dates for the Varna Eneolithic cemetery on the Bulgarian Black Sea coast. Representing the first phase of the AMS dating project for the Varna I cemetery, these dates have been selected to provide a range of different grave locations, ranges of grave goods, and age/gender associations. We conclude by addressing the question of the unexpectedly early start of the cemetery, as well as its apparently short duration and relatively rapid demise.

Results are presented of a comparison of the amino acid (AA) δ(13)C values obtained by gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS) and liquid chromatography-isotope ratio mass spectrometry (LC/IRMS). Although the primary focus was the compound-specific stable carbon isotope analysis of bone collagen AAs, because of its growing application for palaeodietary and palaeoecological reconstruction, the results are relevant to any field where AA δ(13)C values are required. We compare LC/IRMS with the most up-to-date GC/C/IRMS method using N-acetyl methyl ester (NACME) AA derivatives. This comparison involves the analysis of standard AAs and hydrolysates of archaeological human bone collagen, which have been previously investigated as N-trifluoroacetyl isopropyl esters (TFA/IP). It was observed that, although GC/C/IRMS analyses required less sample, LC/IRMS permitted the analysis of a wider range of AAs, particularly those not amenable to GC analysis (e.g. arginine). Accordingly, reconstructed bulk δ(13)C values based on LC/IRMS-derived δ(13)C values were closer to the EA/IRMS-derived δ(13)C values than those based on GC/C/IRMS values. The analytical errors for LC/IRMS AA δ(13)C values were lower than GC/C/IRMS determinations. Inconsistencies in the δ(13)C values of the TFA/IP derivatives compared with the NACME- and LC/IRMS-derived δ(13)C values suggest inherent problems with the use of TFA/IP derivatives, resulting from: (i) inefficient sample combustion, and/or (ii) differences in the intra-molecular distribution of δ(13)C values between AAs, which are manifested by incomplete combustion. Close similarities between the NACME AA δ(13)C values and the LC/IRMS-derived δ(13)C values suggest that the TFA/IP derivatives should be abandoned for the natural abundance determinations of AA δ(13)C values.

Nitrogen stable isotopes analysis of indi- vidual bone collagen amino acids was applied to archeo- logical samples as a new tool for assessing the composi- tion of ancient human diets and calibrating radiocarbon dates. We used this technique to investigate human and faunal samples from the Kitakogane shell midden in Hokkaido, Japan (5,300-6,000 cal BP). Using compound- specific nitrogen isotope analysis of individual amino acids, we aimed to estimate i) the quantitative contribu- tion of marine and terrestrial protein to the human diet, and ii) the mean trophic level (TL) from which dietary protein was derived from marine ecosystems. Data were interpreted with reference to the amino acid trophic level (TLAA) model, which uses empirical amino acid d 15 N from modern marine fauna to construct mathemati- cal equations that predict the trophic position of organ- isms. The TLAA model produced realistic TL estimates for the Kitakogane marine animals. However, this model was not appropriate for the interpretation of human amino acid d 15 N, as dietary protein is derived from both marine and terrestrial environments. Hence, we devel- oped a series of relevant equations that considered the consumption of dietary resources from both ecosystems. Using these equations, the mean percentage of marine protein in the Kitakogane human diet was estimated to be 74%. Although this study is one of the first system- atic investigations of amino acid d 15 N in archeological bone collagen, we believe that this technique is ex- tremely useful for TL reconstruction, palaeodietary interpretation, and the correction of marine reservoir effects for radiocarbon dating. Am J Phys Anthropol 143:31-40, 2010. V