A canine surrogacy approach to human paleodietary bone chemistry: Past development and future directions

When archaeological human remains are absent or otherwise unavailable for bone chemistry-based paleodietary reconstructions, dog remains may provide an appropriate surrogate material for approximating ancient human diet. This "canine surrogacy approach" (CSA) has developed over the past thirty years and is becoming more common in archaeological science literature. A dearth of continued innovation in CSA applications as well as recent criticisms of its feasibility may reflect the absence of a cohesive overview of the approach's development, its underlying analogical nature, as well as variation and inconsistency in the ways it has been applied. Considering the CSA's invaluable potential to partially circumvent the destructive analysis of human remains, thereby addressing the increasingly recognized concerns of indigenous groups, such considerations would be timely and germane. Recent research has characterized the role of analogy in CSA applications and devised a framework for making CSA interpretations (Guiry J Archaeol Method Theory 19(3):351-376, 2012a, b). In contrast to, and complementing that work, this paper provides an outline of the CSA's inception and evolution with particular emphasis on identifying the impetuses for, and trends in, its development. In addition to clarifying the CSA's origin as well as where and why it is applied today, this review provides an opportunity to identify future directions for productive methodological innovation. © 2013 Springer-Verlag Berlin Heidelberg

Dogs as Analogs in Stable Isotope-Based Human Paleodietary Reconstructions: A Review and Considerations for Future Use

In contexts where human remains are scarce, poorly preserved, or otherwise unavailable for stable isotope-based paleodietary reconstruction, dog bone collagen as well as other tissues may provide a suitable proxy material for addressing questions relating to human dietary practices. Inferences drawn from applications of this "canine surrogacy approach" (CSA) must be made with caution to ensure the accuracy and transparency of conclusions. This paper shows that CSA applications are essentially analogical inferences which can be divided into two groups that provide specific types of information and may require different levels of substantiation. A framework of three categories of factors is outlined to aid in establishing positive, negative, and neutral elements of comparison of dog and human diets. CSA applications may benefit from explicitly detailing the type and nature of the analogical reasoning employed and from providing a systematic assessment of the degree to which stable isotope values of dogs and humans under comparison are thought to be like, unlike, or of unknown likeness. © 2011 Springer Science+Business Media, LLC

Quality control for modern bone collagen stable carbon and nitrogen isotope measurements

Methods in Ecology and Evolution published by John Wiley & Sons Ltd on behalf of British Ecological Society Isotopic analyses of collagen, the main protein preserved in subfossil bone and tooth, has long provided a powerful tool for the reconstruction of ancient diets and environments. Although isotopic studies of contemporary ecosystems have typically focused on more accessible tissues (e.g. muscle, hair), there is growing interest in the potential for analyses of collagen because it is often available in hard tissue archives (e.g. scales, skin, bone, tooth), allowing for enhanced long-term retrospective studies. The quality of measurements of the stable carbon and nitrogen isotopic compositions of ancient samples is subject to robust and well-established criteria for detection of contaminants and diagenesis. Among these quality control (QC) criteria, the most widely utilized is the atomic C:N ratio (C:NAtomic), which for ancient samples has an acceptable range between 2.9 and 3.6. While this QC criterion was developed for ancient materials, it has increasingly being applied to collagen from modern tissues. Here, we use a large survey of published collagen amino acid compositions (n = 436) from 193 vertebrate species as well as recent experimental isotopic evidence from 413 modern collagen extracts to demonstrate that the C:NAtomic range used for ancient samples is not suitable for assessing collagen quality of modern and archived historical samples. For modern tissues, collagen C:NAtomic falling outside 3.00–3.30 for fish and 3.00–3.28 for mammals and birds can produce systematically skewed isotopic compositions and may lead to significant interpretative errors. These findings are followed by a review of protocols for improving C:NAtomic criteria for modern collagen extracts. Given the tremendous conservation and environmental policy-informing potential that retrospective isotopic analyses of collagen from contemporary and archived vertebrate tissues have for addressing pressing questions about long-term environmental conditions and species behaviours, it is critical that QC criteria tailored to modern tissues are established

Improved quality control criteria for stable carbon and nitrogen isotope measurements of ancient bone collagen

The carbon (δ13C) and nitrogen (δ15N) isotopic compositions of bone and tooth collagen provide a powerful tool for studying past biological, environmental, and cultural phenomena. Collagen has a well-understood chemical composition that has enabled the development of invaluable quality control (QC) criteria for isotopic data – something that is extremely rare among biogeochemical research on ancient biomolecules as a whole. The most important of these collagen QC criteria is atomic C:N ratio (ratio of carbon to nitrogen atoms), which provides an indicator of the extent to which the amount of carbon and nitrogen present in a sample matches the known composition of pure collagen, thereby indicating whether contamination or diagenesis may be influencing a sample's isotopic compositions. We present a model describing the relationship between the carbon and nitrogen isotopic and elemental compositions that accounts for the isotopic composition of the endogenous collagen and exogenous contaminants as well as taxon-specific information about the collagen's amino acid composition. In some cases the traditional C:N QC parameters are applicable, while in others they can result in the inclusion of unreliable (altered) isotopic data primarily due to contamination from humic substances. Using new and previously published data on taxa commonly encountered in ancient studies, we further illustrate how using traditional C:N QC parameters may lead to the inclusion of altered isotopic compositions in real archaeological and paleontological scenarios. We argue that the traditional ‘one size fits all’ approach to the C:N QC criterion should be avoided and we outline new collagen QC criteria specific to certain taxa and environments on the basis of the results of our model. These revised criteria will help to improve the interpretation of isotopic data by more accurately identifying samples with isotopic compositions altered by contamination

Seaweed‐eating sheep show that δ 34 S evidence for marine diets can be fully masked by sea spray effects

RATIONALE: Stable sulfur isotope compositions (δ34 S values) are a useful marker of terrestrial (lower δ34 S) versus marine (higher δ34 S) diets. In coastal areas, 34 S-enriched sea spray can obscure these marine/terrestrial differences. We sought to establish whether δ34 S values of sea spray-affected terrestrial fauna can be distinguished from those of marine-feeding terrestrial fauna. METHODS: We measured bone and dentine collagen δ34 S values, as well as stable carbon (δ13 C) and nitrogen (δ15 N) isotope compositions via continuous flow-elemental analysis/isotope ratio mass spectrometry of 21 sheep (Ovis aries) raised on < 7 km2 island (North Ronaldsay, UK) that had widely divergent access to marine (seaweed) and heavily sea spray-affected terrestrial (grass) food sources. We also analyzed the bone collagen of marine and terrestrial fauna from this island. RESULTS: Sheep bone collagen showed well-defined trends with highly significant correlations between δ13 C and δ15 N values indicative of feeding along a continuum of fully terrestrial to fully marine diets, consistent with other modern baseline data from marine and terrestrial animals in the same area. In contrast, the δ34 S value was generally elevated for all sheep and was not significantly correlated with either δ13 C or δ15 N. CONCLUSIONS: Our findings demonstrate that δ34 S values are poorly suited to differentiate marine and terrestrial diets in terrestrial animals in areas with pronounced sea spray effects. Care must be taken to characterize the isotopic compositions of potential food items before the δ34 S value is used as a marker of the reliance on marine protein in modern and ancient contexts

Domestic dog (canis familiaris) diets among coastal late archaic groups of northeastern north america: A case study for the canine surrogacy approach

The Canine Surrogacy Approach (CSA) is a form of analogy in which stable isotope information from dog remains is used as a proxy for associated human keepers. The approach has garnered increasing attention in recent years due to its capacity to provide information on human diets in contexts where human remains are limited or unavailable. CSA applications have often been conducted on an ad hoc basis and rarely has the human-dog analogy been treated systematically or cohesively. This case study aims to remedy this issue. Using a recently developed CSA interpretive framework (Guiry, 2012), we test the feasibility of using dog bone collagen stable carbon and nitrogen isotope signatures as a proxy for their human keepers among two similar marine oriented Late Archaic populations that occupied the northeastern coast of North America. After characterizing the feasibility of CSA applications in these archaeological contexts, the CSA is then used to reconstruct diet at a culturally related site at which no human remains have been recovered. © 2013 Elsevier Inc

Stable-Isotope Bone Chemistry and Human/Animal Interactions in Historical Archaeology

Stable isotope–based paleodietary work is ideally suited for answering questions about a wide variety of human/animal relationships in historical archaeological contexts in northeastern North America and farther afield. To date, very few published studies have approached historical animal husbandry and trade from an isotopic perspective. We advocate for increased attention to the possibilities of stable-isotope work by (1) explaining why the technique is well suited to address some problems of human/animal relations encountered by historical archaeologists, (2) presenting a literature review of previous stable-isotope work on human/ animal interaction in historical North America, and (3) offering a short case study on the dietary life history of an individual pig raised at the archaeological site of Ferryland, Newfoundland, Canada, based on stable carbon- and nitrogen-isotope data from serially sectioned dental collagen

Inferring Human Behaviors from Isotopic Analyses of Rat Diet: a Critical Review and Historical Application

Rat (Rattus spp.) bone collagen stable isotope values are often assumed to reflect an average of food stuffs that were available to archaeological populations. This paper considers the feasibility of using stable isotope evidence from rat remains as a source of proxy information for human food-related social, economic, and sensorial behaviors. First, a literature review of archaeological and modern ecological rat isotope work reveals that, while rat dietary signatures are often a reasonable proxy for human food waste, they will not always record an unbiased average of foods which are available in a given environment. Second, an overview of ethological, biological, and environmental factors that can influence rat diets is given from the perspective of archaeological bone chemistry, to help identify factors that require explicit and critical consideration when rat stable isotope data is taken as a proxy for human food-related behaviors. Finally, rat stable isotope values are considered to provide new evidence about the social and economic responses of an important historical English fishing community at Ferryland (CgAf-02) to conflict and political turmoil at the turn of the eighteenth century. These results also highlight how information on rat diets can provide a counterpoint to other common faunal isotope approaches that focus on dogs and pigs as a proxy for human dietary behaviors

Integrating fish scale and bone isotopic compositions for ‘deep time’ retrospective studies: Longer isotopic retrospectives from integrating fish tissues

Isotopic studies of archived fish scales have tremendous potential to develop long-term retrospectives that provide important insights into how humans have altered aquatic ecosystems. However, fish specimens in museum archives and other repositories typically date to time periods when the impacts of industrial societies may have already caused profound environmental changes. Archaeological fish bones offer an opportunity to bridge this key temporal gap by providing samples spanning from the recent past to as far back as the Pleistocene. Collagen is the primary protein component of both fish scale and bone, but the comparability of isotopic compositions from these tissues has not been established experimentally. To lay the framework for integrating isotopic datasets from these tissues, we compare δ13C and δ15N of bone and scale collagen, as well as other tissues, from fish with life-time controlled diets. Results show that while there is no difference in δ13C between scale and bone collagen, there may be a very slight but meaningful inter-tissue offset in δ15N (<0.3‰). We discuss potential sources of δ15N variation in scale and bone collagen measurements. Because there is no difference in scale and bone δ13C, and the observed offset in δ15N is very small (less than analytical uncertainty in many studies), our findings demonstrate that collagen isotopic compositions from these tissues should be directly comparable when integrating datasets from modern and ancient samples to build more powerful, millennium-scale isotopic times series. In linking isotopic compositions of collagen from modern, historical (scales), and archaeological (bones) fish, our findings open the way for more nuanced contextualization of how ecosystems functioned prior to large-scale exploitation and how they have responded to mounting anthropogenic pressures in the intervening centuries

Mesolithic dietary heterogeneity on the European Atlantic Coastline: Stable isotope insights into hunter-gatherer diet and subsistence in the Sado Valley, Portugal

Stable carbon and nitrogen isotope data from the bone collagen of human remains excavated in the Sado Valley in the Alentejo region of Portugal provide evidence for the existence of two Mesolithic communities living in close proximity along the shores of an estuarine environment with significantly different diets. These findings add to the limited isotope paleodiet data set from this period in southern Europe and offer a valuable contribution to understandings of the wider European Mesolithic along the Atlantic coastline by (1) providing evidence of coastal Mesolithic hunter-gatherers with mainly terrestrial diets in Europe and (2) suggesting the presence of regional heterogeneity, at a small geographical scale, in subsistence choices among coastal Mesolithic groups. These results show the complexity of human subsistence adaptations in the European Mesolithic and have wider-reaching implications for understanding hunter-gatherer group interactions