Are elevated δ 15 N values in herbivores in hot and arid environments caused by diet or animal physiology?

First evidence for human occupation of a lava tube in Arabia: The archaeology of Umm Jirsan Cave and its surroundings, northern Saudi Arabia

Recent advances in interdisciplinary archaeological research in Arabia have focused on the evolution and historical development of regional human populations as well as the diverse patterns of cultural change, migration, and adaptations to environmental fluctuations. Obtaining a comprehensive understanding of cultural developments such as the emergence and lifeways of Neolithic groups has been hindered by the limited preservation of stratified archaeological assemblages and organic remains, a common challenge in arid environments. Underground settings like caves and lava tubes, which are prevalent in Arabia but which have seen limited scientific exploration, offer promising opportunities for addressing these issues. Here, we report on an archaeological excavation and a related survey at and around Umm Jirsan lava tube in the Harrat Khaybar, north-western Saudi Arabia. Our results reveal repeated phases of human occupation of the site ranging from at least the Neolithic through to the Chalcolithic/Bronze Age. Pastoralist use of the lava tube and surrounding landscape is attested in rock art and faunal records, suggesting that Umm Jirsan was situated along a pastoral route linking key oases. Isotopic data indicates that herbivores primarily grazed on wild grasses and shrubs rather than being provided with fodder, while humans had a diet consistently high in protein but with increasing consumption of C3 plants through-time, perhaps related to the emergence of oasis agriculture. While underground and naturally sheltered localities are globally prominent in archaeology and Quaternary science, our work represents the first such combined records for Saudi Arabia and highlight the potential for interdisciplinary studies in caves and lava tubes.

Carbon (δ13C) and nitrogen (δ15N) isotope ratios reveal geographic affinity and dietary status of Ajnala skeletal remains: A forensic anthropological study

Stable isotope analysis from bones and teeth has been widely used to estimate the likely geographic locations and dietary status of individuals whose osseous remains have been retrieved from some forensic or bio-archaeological contexts. The carbon and nitrogen stable isotope signatures can provide insights into geographic affinity and dietary habits. Ajnala skeletal remains represent a serious crime against humanity committed in past by colonial rulers and by amateur archaeologists of modern times. In present study, isotopic concentrations of carbon (δ13C) and nitrogen (δ15N) estimated from 21 mandibular molars have been used to estimate the local or non-local status of badly damaged skeletal remains retrieved from an abandoned well at Ajnala (India). The collagen samples having C/N ratio within range of 2.8-3.6 were considered as well-preserved and non-contaminated ones. The isotope concentrations of carbon and nitrogen varied from -18.7‰ to -22.9‰ and +7.6‰ to +11.7‰, with an average of -20.49 ± 1.2‰ and +9.31 ± 1.1‰, respectively. The analysis of the obtained isotope values reflected the consumption of C3/C4 mixed diet by majority of the individuals, and such type of dietary habits are mainly restricted to the reported Indo-Gangatic plain of India to which slain soldiers reportedly belonged to. These observations corroborated the previous observations about the geographic affinity and dietary status of Ajnala individuals. Though C and N isotopes are by and large not the confirmed/direct indicators of geographic origin, they can provide corroboratory information to support other observations narrowing down the dietary habits of individuals of certain specific geographical regions.

Tooth enamel nitrogen isotope composition records trophic position: a tool for reconstructing food webs

Nitrogen isotopes are widely used to study the trophic position of animals in modern food webs; however, their application in the fossil record is severely limited by degradation of organic material during fossilization. In this study, we show that the nitrogen isotope composition of organic matter preserved in mammalian tooth enamel (δ¹⁵N_enamel) records diet and trophic position. The δ¹⁵N_enamel of modern African mammals shows a 3.7‰ increase between herbivores and carnivores as expected from trophic enrichment, and there is a strong positive correlation between δ¹⁵N_enamel and δ¹⁵N_{bone-collagen} values from the same individuals. Additionally, δ¹⁵N_enamel values of Late Pleistocene fossil teeth preserve diet and trophic level information, despite complete diagenetic loss of collagen in the same specimens. We demonstrate that δ¹⁵N_enamel represents a powerful geochemical proxy for diet that is applicable to fossils and can help delineate major dietary transitions in ancient vertebrate lineages.

Nitrogen palaeo-isoscapes: Changing spatial gradients of faunal δ15N in late Pleistocene and early Holocene Europe

Nitrogen isotope ratio analysis (δ15N) of animal tissue is widely used in archaeology and palaeoecology to investigate diet and ecological niche. Data interpretations require an understanding of nitrogen isotope compositions at the base of the food web (baseline δ15N). Significant variation in animal δ15N has been recognised at various spatiotemporal scales and related to changes both in baseline δ15N, linked to environmental and climatic influence on the terrestrial nitrogen cycle, and animal ecology. Isoscapes (models of isotope spatial variation) have proved a useful tool for investigating spatial variability in biogeochemical cycles in present-day marine and terrestrial ecosystems, but so far, their application to palaeo-data has been more limited. Here, we present time-sliced nitrogen isoscapes for late Pleistocene and early Holocene Europe (c. 50,000 to 10,000 years BP) using herbivore collagen δ15N data. This period covers the Last Glacial-Interglacial Transition, during which significant variation in the terrestrial nitrogen cycle occurred. We use generalized linear mixed modelling approaches for interpolation and test models which both include and exclude climate covariate data. Our results show clear changes in spatial gradients of δ15N through time. Prediction of the lowest faunal δ15N values in northern latitudes after, rather than during, the Last Glacial Maximum is consistent with the Late Glacial Nitrogen Excursion (LGNE). We find that including climatic covariate data does not significantly improve model performance. These findings have implications for investigating the drivers of the LGNE, which has been linked to increased landscape moisture and permafrost thaw, and for understanding changing isotopic baselines, which are fundamental for studies investigating diets, niche partitioning, and migration of higher trophic level animals.

Carbon, nitrogen, and oxygen stable isotopes in modern tooth enamel: A case study from Gorongosa National Park, central Mozambique

The analyses of the stable isotope ratios of carbon (δ13C), nitrogen (δ15N), and oxygen (δ18O) in animal tissues are powerful tools for reconstructing the feeding behavior of individual animals and characterizing trophic interactions in food webs. Of these biomaterials, tooth enamel is the hardest, most mineralized vertebrate tissue and therefore least likely to be affected by chemical alteration (i.e., its isotopic composition can be preserved over millions of years), making it an important and widely available archive for biologists and paleontologists. Here, we present the first combined measurements of δ13C, δ15N, and δ18O in enamel from the teeth of modern fauna (herbivores, carnivores, and omnivores) from the well-studied ecosystem of Gorongosa National Park (GNP) in central Mozambique. We use two novel methods to produce high-precision stable isotope enamel data: (i) the “oxidation-denitrification method,” which permits the measurement of mineral-bound organic nitrogen in tooth enamel (δ15Nenamel), which until now, has not been possible due to enamel’s low organic content, and (ii) the “cold trap method,” which greatly reduces the sample size required for traditional measurements of inorganic δ13Cenamel and δ18Oenamel (from ≥0.5 to ≤0.1 mg), permitting analysis of small or valuable teeth and high-resolution serial sampling of enamel. The stable isotope results for GNP fauna reveal important ecological information about the trophic level, dietary niche, and resource consumption. δ15Nenamel values clearly differentiate trophic level (i.e., carnivore δ15Nenamel values are 4.0‰ higher, on average, than herbivores), δ13Cenamel values distinguish C3 and/or C4 biomass consumption, and δ18Oenamel values reflect local meteoric water (δ18Owater) in the park. Analysis of combined carbon, nitrogen, and oxygen stable isotope data permits geochemical separation of grazers, browsers, omnivores, and carnivores according to their isotopic niche, while mixed-feeding herbivores cannot be clearly distinguished from other dietary groups. These results confirm that combined C, N, and O isotope analyses of a single aliquot of tooth enamel can be used to reconstruct diet and trophic niches. Given its resistance to chemical alteration, the analysis of these three isotopes in tooth enamel has a high potential to open new avenues of research in (paleo)ecology and paleontology.

Herd management and subsistence practices as inferred from isotopic analysis of animals and plants at Bronze Age Politiko-Troullia, Cyprus

The Bronze Age village of Politiko-Troullia, located in the foothills of the copper-bearing Troodos mountains of central Cyprus, was occupied ~2050-1850 cal BCE. Excavated evidence shows that community activities included copper metallurgy (ore processing, smelting and casting), crop cultivation, and rearing of livestock. Faunal analysis reveals day-to-day subsistence practices that included consumption of sheep, goat, cattle, and pig, as well as community-scale ritual feasting focused on fallow deer, Dama dama mesopotamica. In this paper, we present bone collagen stable isotope data from these taxa to infer how these animals were managed. We incorporate stable isotope baselines calculated from modern cereal grains and compare these to archaeological seeds from Politiko-Troullia. Mean values of δ13C and δ15N cluster for livestock consistent with a diet of C3 plants, with a wider range in goats that suggests free-browsing herds. Higher δ15N values in cattle may reflect supplemental feeding or grazing in manured fields. Plant isotope values suggest livestock diets were predominantly composed of cultivated taxa. In contrast, deer and pig bones produce more negative mean δ13C and δ15N values suggesting that the villagers of Politiko-Troullia complemented their management of domesticated animals with hunting of wild deer and feral pigs in the woodlands surrounding their village.

Diversification in Feeding Pattern of Livestock in Early Bronze Age Northwestern China

Animal husbandry has been an indispensable part of human subsistence since the origin of agriculture. Along with the prehistoric cultural exchange, several kinds of major domestic animals diffused and gradually got popularized across the Eurasia. The specific geographic setting makes the Hexi Corridor in northwestern China one of the key regions to converge various types of major crops and livestock, and to witness the deep impact of novel species on local subsistence. Archeological evidence reveals an emergence of early oriental-occidental cultural communication at the opening of the local Bronze Age in Hexi Corridor, resulting in a significant shift of local subsistence. However, due to the lack of more detailed archeological evidence, the initial timing and trajectory of the transformation of livestock feeding patterns remain unclear. In this study, we reported systematic stable isotope and precise radiocarbon dating analyses on faunal remains unearthed from Huoshiliang and Ganggangwa, two Early Bronze Age settlements (ca. 4,000–3,700 BP) in middle Hexi Corridor. Our results show distinct diversification in livestock feeding patterns at ∼3,850 cal BP; in contrast with previous periods, some omnivorous livestock appear to have consumed mainly C3 foodstuff and some herbivorous livestock primarily consumed C4 plants. Combined with published stable isotope data and other archeological findings in the neighboring region, a clearer trajectory of the evolution of livestock feeding patterns has been revealed with diversified strategy amid the transformation during the Early Bronze Age in Hexi Corridor. We argued that the alteration of the local livestock feeding pattern reflects the attempt to achieve more efficient economy and sustainable society, in order to withstand the harsh arid environment in Hexi Corridor.

Evaluating Water Fertilizer Coupling on the Variations in Millet Chaff Size during the Late Seventh Century in Northwest China: Morphological and Carbon and Nitrogen Isotopic Evidence from the Chashancun Cemetery

Stable isotopic analyses of the remains of plants that have been unearthed from archaeological sites are often featured as key indicators of crop cultivation and the living environment. However, systematic archaeobotanical studies have not been applied widely in Chinese historical sites, especially in those from the Tang dynasty. This paper aims to use carbon and nitrogen isotopic analyses to reveal the potential influence of water and fertilizer conditions on the size of millet chaffs that were excavated from the Chashancun cemetery. To achieve this, >3600 uncharred broomcorn and foxtail millet chaff remains were measured. Furthermore, 30 broomcorn millet samples and 30 foxtail millet samples were selected to analyze the carbon and nitrogen isotopes, respectively. The widths and thicknesses of the broomcorn millet chaffs ranged from 1.11 to 2.38 mm and from 0.95 to 2.24 mm, respectively, while those of the foxtail millet chaffs ranged from 0.95 to 1.94 mm and from 0.69 to 1.90 mm, respectively. The δ13C and δ15N values of the broomcorn millet chaffs ranged from −13.0‰ to −12.0‰ and from 15.7‰ to 17.8‰, respectively, while those of the foxtail millet chaffs ranged from −14.0‰ to −12.9‰ and from 15.7‰ to 18.8‰, respectively. The results show correlations between the millet chaff size and the carbon/nitrogen isotopic values, suggesting that water and fertilizer conditions might have significantly affected millet grain yield during the late seventh century in northwestern China.

Isotope data from amino acids indicate Darwin's ground sloth was not an herbivore

Fossil sloths are regarded as obligate herbivores for reasons including peculiarities of their craniodental morphology and that all living sloths feed exclusively on plants. We challenge this view based on isotopic analyses of nitrogen of specific amino acids, which show that Darwin's ground sloth Mylodon darwinii was an opportunistic omnivore. This direct evidence of omnivory in an ancient sloth requires reevaluation of the ecological structure of South American Cenozoic mammalian communities, as sloths represented a major component of these ecosystems across the past 34 Myr. Furthermore, by analyzing modern mammals with known diets, we provide a basis for reliable interpretation of nitrogen isotopes of amino acids of fossils. We argue that a widely used equation to determine trophic position is unnecessary, and that the relative isotopic values of the amino acids glutamate and phenylalanine alone permit reliable reconstructions of trophic positions of extant and extinct mammals.

Localized management of non-indigenous animal domesticates in Northwestern China during the Bronze Age

The movements of ancient crop and animal domesticates across prehistoric Eurasia are well-documented in the archaeological record. What is less well understood are the precise mechanisms that farmers and herders employed to incorporate newly introduced domesticates into their long-standing husbandry and culinary traditions. This paper presents stable isotope values (δ¹³C, δ¹⁵N) of humans, animals, and a small number of plants from the Hexi Corridor, a key region that facilitated the movement of ancient crops between Central and East Asia. The data show that the role of animal products in human diets was more significant than previously thought. In addition, the diets of domestic herbivores (sheep/goat, and cattle) suggest that these two groups of domesticates were managed in distinct ways in the two main ecozones of the Hexi Corridor: the drier Northwestern region and the wetter Southeastern region. Whereas sheep and goat diets are consistent with consumption of naturally available vegetation, cattle exhibit a higher input of C₄ plants in places where these plants contributed little to the natural vegetation. This suggests that cattle consumed diets that were more influenced by human provisioning, and may therefore have been reared closer to the human settlements, than sheep and goats.

Camelid husbandry in the Atacama Desert? A stable isotope study of camelid bone collagen and textiles from the Lluta and Camarones Valleys, northern Chile

Management of camelids in the coastal valleys of the Andes has generated much debate in recent years. Zooarchaeological and isotopic studies have demonstrated that in the coastal valleys of northern and southern Peru there were locally maintained camelid herds. Because of the hyperarid conditions of the northern coast of Chile, this region has been assumed to be unsuitable for the raising of camelids. In this study we report stable carbon and nitrogen isotopic compositions of camelid bone collagen and textiles made from camelid fiber from Late Intermediate Period (LIP) and Late Horizon (LH) occupations in northern Chilean river valleys. The camelid bone collagen isotopic compositions are consistent with these animals originating in the highlands, although there is a significant difference in the camelids dating to the LIP and LH, possibly because of changes made to distribution and exchange networks by the Inca in the LH. There were no differences between the isotopic compositions of the camelid fibers sampled from textiles in the LIP and LH, suggesting that either the production of camelid fiber was unchanged by the Inca or the changes that were made do not present visible isotopic evidence. Several camelid fiber samples from both the LIP and LH present very high δ13C and δ15N values, comparable to human hair samples from one site (Huancarane) in the Camarones Valley. These data suggest that people in the northern valleys of Chile may have kept small numbers of animals specifically for fiber production. Overall, however, the vast majority of the textile samples have isotopic compositions that are consistent with an origin in the highlands. These data suggest that the hyperarid coastal river valleys of northern Chile did not support substantial camelid herds as has been interpreted for northern Peru.

Stoichiometric and stable isotope ratios of wild lizards in an urban landscape vary with reproduction, physiology, space and time

Spatial and temporal variation in stoichiometric and stable isotope ratios of animals contains ecological information that we are just beginning to understand. In both field and lab studies, stoichiometric or isotopic ratios are related to physiological mechanisms underlying nutrition or stress. Conservation and ecosystem ecology may be informed by isotopic data that can be rapidly and non-lethally collected from wild animals, especially where human activity leaves an isotopic signature (e.g. via introduction of chemical fertilizers, ornamental or other non-native plants or organic detritus). We examined spatial and temporal variation in stoichiometric and stable isotope ratios of the toes of Uta stansburiana (side-blotched lizards) living in urban and rural areas in and around St. George, Utah. We found substantial spatial and temporal variation as well as context-dependent co-variation with reproductive physiological parameters, although certain key predictions such as the relationship between δ¹⁵N and body condition were not supported. We suggest that landscape change through urbanization can have profound effects on wild animal physiology and that stoichiometric and stable isotope ratios can provide unique insights into the mechanisms underlying these processes.

Climate stability and societal decline on the margins of the Byzantine empire in the Negev Desert

Understanding past human settlement of inhospitable regions is one of the most intriguing puzzles in archaeological research, with implications for more sustainable use of marginal regions today. During the Byzantine period in the 4^th century CE, large settlements were established in the arid region of the Negev Desert, Israel, but it remains unclear why it did so, and why the settlements were abandoned three centuries later. Previous theories proposed that the Negev was a “green desert” in the early 1^st millennium CE, and that the Byzantine Empire withdrew from this region due to a dramatic climatic downturn. In the absence of a local climate archive correlated to the Byzantine/Early Islamic transition, testing this theory has proven challenging. We use stable isotopic indicators of animal dietary and mobility patterns to assess the extent of the vegetative cover in the desert. By doing so, we aim to detect possible climatic fluctuations that may have led to the abandonment of the Byzantine settlements. The findings show that the Negev Desert was not greener during the time period under investigation than it is today and that the composition of the animals’ diets, as well as their grazing mobility patterns, remained unchanged through the Byzantine/Early Islamic transition. Favoring a non-climatic explanation, we propose instead that the abandonment of the Negev Byzantine settlements was motivated by restructuring of the Empire’s territorial priorities.

Adaptability, resilience and environmental buffering in European Refugia during the Late Pleistocene: Insights from La Riera Cave (Asturias, Cantabria, Spain)

The Upper Palaeolithic in Europe was a time of extensive climatic changes that impacted on the survival and distribution of human populations. During the Late Glacial Maximum (LGM), southern European peninsulas were refugia for flora, fauna, and human groups. One of these refugia, the Cantabrian region (northern Atlantic Spain), was intensively occupied throughout the Upper Palaeolithic. Characterising how climatic events were expressed in local environments is crucial to understand human and animal survival. La Riera Cave (Asturias) has a rich geo-cultural sequence dating between 20.5kyr BP to 6.5kyr BP and represents an ideal location in which to explore this. Stable isotope analysis of red deer and ibex is used alongside other environmental and climatic proxies to reconstruct Late Upper Palaeolithic conditions. Results show that during the LGM, ibex adapted their niche to survive, and became a major prey species for humans. The diverse environmental opportunities offered in the high-relief and coastal environs of La Riera may help to explain the high human population levels in the Cantabrian Region throughout the Late Upper Palaeolithic. Despite fluctuating conditions, herbivores and humans had the flexibility and resilience to adapt, demonstrating the importance of southern European refugia for the survival of different species.

Carbon and nitrogen isotopic signatures of hair, nail, and breath from tropical African human populations

RATIONALE

Stable isotopic analyses are increasingly used to study the diets of past and present human populations. Yet, the carbon and nitrogen isotopic data of modern human diets collected so far are biased towards Europe and North America. Here, we address this gap by reporting on the dietary isotopic signatures of six tropical African communities: El Molo, Turkana (Kerio), Luhya (Webuye), Luhya (Port Victoria), and Luo (Port Victoria) from Kenya, and Baka from Cameroon; representing four subsistence strategies: fishing, pastoralism, agriculturalism, and hunter-gatherer.

METHODS

We used an elemental analyser coupled in continuous-flow mode to an isotope ratio mass spectrometer to measure the carbon and nitrogen isotopic ratios of hair (n = 134) and nail (n = 80) and the carbon isotopic ratios of breath (n = 184) from these communities, as well as the carbon and nitrogen isotopic ratios of some food samples from the Kenyan communities.

RESULTS

We expand on the known range of δ¹³ C values in human hair through the hunter-gatherer Baka, with a diet based on C₃ plants, and through the agriculturalist Luhya (Webuye), with a diet based on C₄ plants. In addition, we found that the consumption of fish from East African lakes is difficult to detect isotopically due to the combined effects of high nitrogen isotopic ratios of plants and the low nitrogen isotopic ratios of fish. Finally, we found that some of the communities studied are markedly changing their diets through increasing sedentism and urbanisation.

CONCLUSIONS

Our findings contribute substantially to the understanding of the environmental, demographic, and economic dynamics that affect the dietary landscape of different tropical populations of Africa. These results highlight the importance of studying a broader sample of human populations and their diet, with a focus on their precise context - from both isotopic and more general anthropological perspectives.

Diet variability among pre-Dogon and early Dogon populations (Mali) from stable isotopes and dental diseases

AIMS AND OBJECTIVES

This article reports on diet variability in the Dogon Country (Mali) through a bio-archeological study of pre-Dogon and early Dogon human remains (7th century to 19th century AD) from collective burial caves in the Bandiagara Escarpment.

MATERIALS AND METHODS

Two hundred and twenty crania from collections curated in Leiden, Paris, and Bamako were studied for dental diseases. In a subset of teeth (n = 175), δ¹³ C and δ¹⁵ N were measured in bulk dentine samples.

RESULTS

δ¹³ C and δ¹⁵ N values vary widely (-15.4 to -6.0‰ for δ¹³ C, 6.0-14.8‰ for δ¹⁵ N, n = 175), and indicate diets dominated by C₄ -based foods with a focus on plants; animal products played a minor role. There are significant differences between the δ¹³ C values from older (pre-Dogon) and younger (Dogon) periods. Frequencies of caries, antemortem tooth loss, and abscesses increase significantly through time. Individuals from northern caves have more positive δ¹³ C and δ¹⁵ N values than southern ones.

DISCUSSION AND CONCLUSIONS

The temporal shifts are probably due to progressive diversification of foods, consistent with archeological evidence showing the addition of rice and vegetables to pearl millet. The geographical disparity is explained by a combination of climatic, environmental, and cultural factors. Last, intersite differences imply that different communities (or subsections thereof) disposed of their dead in different caves. Based on a large sample extending over a wider area and longer time frame than previous work, our study shows that diets in the Dogon Country were neither uniform nor continuous through time, as previously proposed. Our results attest to a complex history of settlement and foodways.

Evolutionary history and palaeoecology of brown bear in North-East Siberia re-examined using ancient DNA and stable isotopes from skeletal remains

Over 60% of the modern distribution range of brown bears falls within Russia, yet palaeoecological data from the region remain scarce. Complete modern Russian brown bear mitogenomes are abundant in the published literature, yet examples of their ancient counterparts are absent. Similarly, there is only limited stable isotopic data of prehistoric brown bears from the region. We used ancient DNA and stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes retrieved from five Pleistocene Yakutian brown bears (one Middle Pleistocene and four Late Pleistocene), to elucidate the evolutionary history and palaeoecology of the species in the region. We were able to reconstruct the complete mitogenome of one of the Late Pleistocene specimens, but we were unable to assign it to any of the previously published brown bear mitogenome clades. A subsequent analysis of published mtDNA control region sequences, which included sequences of extinct clades from other geographic regions, assigned the ancient Yakutian bear to the extinct clade 3c; a clade previously identified from Late Quaternary specimens from Eastern Beringia and Northern Spain. Our analyses of stable isotopes showed relatively high δ¹⁵N values in the Pleistocene Yakutian brown bears, suggesting a more carnivorous diet than contemporary brown bears from Eastern Beringia.

Revisiting the Foraging Ecology and Extinction History of Two Endemic Vertebrates from Tenerife, Canary Islands

We used carbon (δ13C) and nitrogen (δ15N) isotopes to examine the foraging ecology of Tenerife giant rats (Canariomys bravoi) and lizards (Gallotia goliath) in northwestern Tenerife, which until recently, were the island’s largest terrestrial vertebrates. We combined new isotope data for 28 C. bravoi and 14 G. goliath with published regional data for both species and then compared these with data for co-occurring extant taxa and modern C3 plants. Isotope data suggest both extinct species relied primarily on C3 resources and were trophic omnivores. However, the two species appear to have partitioned their resources when living in sympatry. Isotopic overlap between C. bravoi and Rattus spp., and between G. goliath, extant Gallotia galloti, and introduced rabbits (Oryctolagus cuniculus) suggests reliance on similar foods. We radiocarbon dated four C. bravoi and two G. goliath with the most extreme isotope values. These new dates do not settle the question of what triggered the demise of either species. Nevertheless, the data are most consistent with anthropogenically-induced extinction. Temporal isotopic trends contradict expectations if regional climate were responsible, and confidence intervals for radiocarbon dates suggest it is highly likely that both species were present when humans first settled the island.

Jaguar and puma captivity and trade among the Maya: Stable isotope data from Copan, Honduras

From Moctezuma’s zoo to animals kept in captivity at Teotihuacan, there is increasing evidence that Mesoamericans managed wild animals for a myriad of purposes. The present study situates ritualized animal management of highly symbolic fauna in the broader context of Classic Mesoamerica by examining another core site, the Maya center of Copan, Honduras (A.D. 426–822). In this study, we identify two animal populations among the faunal remains from public and private rituals spanning the Copan dynasty. One population, with diets heavily composed of atypically sourced C₄ inputs indicative of artificial feeding, corresponds with the felids interred in Altar Q and Motmot caches. The second population is composed of felids and felid products bearing a predominance of C₃ signatures indicative of a more natural dietary regime. As with Copan deer, species-specific δ¹⁸O variations within these felid populations further substantiates the postulation that an expansive faunal trade network operated throughout the greater Copan Valley and beyond. Animals routed from sites of capture into the mesh of this network would have been processed into pelts, venison and other secondary goods or delivered alive to centers of state power for ritual usage and display. Our data reveal that at Copan, wild animals were routinely brought into intimate contact with human settlements to be managed and physically manipulated in a variety of ways in order to fulfill ritual and symbolic purposes.

Climatic controls on Later Stone Age human adaptation in Africa's southern Cape

Africa's southern Cape is a key region for the evolution of our species, with early symbolic systems, marine faunal exploitation, and episodic production of microlithic stone tools taken as evidence for the appearance of distinctively complex human behavior. However, the temporally discontinuous nature of this evidence precludes ready assumptions of intrinsic adaptive benefit, and has encouraged diverse explanations for the occurrence of these behaviors, in terms of regional demographic, social and ecological conditions. Here, we present a new high-resolution multi-proxy record of environmental change that indicates that faunal exploitation patterns and lithic technologies track climatic variation across the last 22,300 years in the southern Cape. Conditions during the Last Glacial Maximum and deglaciation were humid, and zooarchaeological data indicate high foraging returns. By contrast, the Holocene is characterized by much drier conditions and a degraded resource base. Critically, we demonstrate that systems for technological delivery - or provisioning - were responsive to changing humidity and environmental productivity. However, in contrast to prevailing models, bladelet-rich microlithic technologies were deployed under conditions of high foraging returns and abandoned in response to increased aridity and less productive subsistence environments. This suggests that posited links between microlithic technologies and subsistence risk are not universal, and the behavioral sophistication of human populations is reflected in their adaptive flexibility rather than in the use of specific technological systems.

When maize is not the first choice: advances in paleodietary studies in the Archaeological Site Río Doncellas (Jujuy, Argentina)

In this work we present new values of stable isotopes of carbon (δ13Cco and δ13Cap) and nitrogen (δ15N) measured in a sample of 13 human individuals found in the Río Doncellas Archaeological Site (Late Period or Regional Developments, ca. 1000 AD-1450 AD) located in the Puna of Jujuy, Northwest of Argentina. The skeletal series belong to the collection of Museo E. Casanova, FFyL - UBA and the Instituto Nacional de Antropología y Pensamiento Latinoamericano, being the result of investigations carried out during the decades of 1940 and 1970, respectively. In addition, in this work we present isotopic compositions of food resources (vegetal and fauna) found in the archaeological record as well as gathered in modern farms located in the study area (Abra Pampa, Cochinoca, Jujuy). This information was used for paleodietary inference, allowing us to establish a hierarchy of the resources that were consumed. The results indicate that maize (Zea mays) is less important than other vegetal resources in the diet, which contradicts the expectations generated from the macrobotanical evidence of the site and the cultivated terraces that surround it. On the other hand, camelids seemed to be widely exploited, which is coherent with the current importance of meat production within the region. These results allow us to assert that the growth of cereals did not have a progressive relevance over other resources.

Nitrogen cycling in an extreme hyperarid environment inferred from δ(15)N analyses of plants, soils and herbivore diet

Climate controls on the nitrogen cycle are suggested by the negative correlation between precipitation and δ¹⁵N values across different ecosystems. For arid ecosystems this is unclear, as water limitation among other factors can confound this relationship. We measured herbivore feces, foliar and soil δ¹⁵N and δ¹³C values and chemically characterized soils (pH and elemental composition) along an elevational/climatic gradient in the Atacama Desert, northern Chile. Although very positive δ¹⁵N values span the entire gradient, soil δ¹⁵N values show a positive correlation with aridity as expected. In contrast, foliar δ¹⁵N values and herbivore feces show a hump-shaped relationship with elevation, suggesting that plants are using a different N source, possibly of biotic origin. Thus at the extreme limits of plant life, biotic interactions may be just as important as abiotic processes, such as climate in explaining ecosystem δ¹⁵N values.

Environmental variables across Pan troglodytes study sites correspond with the carbon, but not the nitrogen, stable isotope ratios of chimpanzee hair

Diet influences the stable isotope ratios of carbon and nitrogen (δ(13) C and δ(15) N values) in animal tissue; but here we explore the influences of particular aspects of the local environment on those values in chimpanzees (Pan troglodytes). In this article we present new δ(13) C and δ(15) N values in Gombe chimpanzees using hairs collected from night nests in 1989. Then, we explore the influence of environmental factors by comparing our Gombe data to those from eight additional Pan study sites with previously published stable isotope data. We compare chimpanzee δ(13) Chair and δ(15) Nhar values to specific characteristics of local site ecology (biome and ecoregion) and to local Mean Annual Precipitation (MAP) to test hypotheses based on known effects of these variables on the δ(13) C and δ(15) N values in plant tissues. The comparison shows that hair from chimpanzees living in savanna sites with lower MAP have higher δ(13) Chair values than do chimpanzees living in woodland and forested sites with higher MAP. These results demonstrate the potential of using δ(13) C values in primate tissue to indicate aspects of their local ecology in cases where the ecology is uncertain, such as samples collected early in the last century and in fossil hominins. In contrast to expectations, however, chimpanzee δ(15) Nhair values from some savanna sites with lower MAP are lower, not higher, than those living in more forested areas with higher MAP. It is likely that diet selectivity by chimpanzees affects δ(15) Nhair values to a greater extent than does the influence of precipitation on plants. Am. J. Primatol. 78:1055-1069, 2016. © 2015 Wiley Periodicals, Inc.

Stable Isotope Ratios as Biomarkers of Diet for Health Research

Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment. Consequently, there is a pressing need for more objective biomarkers of diet for use in health research. The stable isotope ratios of light elements are a promising set of candidate biomarkers because they vary naturally and reproducibly among foods, and those variations are captured in molecules and tissues with high fidelity. Recent studies have identified valid isotopic measures of short- and long-term sugar intake, meat intake, and fish intake in specific populations. These studies provide a strong foundation for validating stable isotopic biomarkers in the general US population. Approaches to improve specificity for specific foods are needed; for example, by modeling intake using multiple stable isotope ratios or by isolating and measuring specific molecules linked to foods of interest.

Seasonal variation in stable carbon and nitrogen isotope values of bats reflect environmental baselines

The stable carbon and nitrogen isotope composition of animal tissues is commonly used to trace wildlife diets and analyze food chains. Changes in an animal's isotopic values over time are generally assumed to indicate diet shifts or, less frequently, physiological changes. Although plant isotopic values are known to correlate with climatic seasonality, only a few studies restricted to aquatic environments have investigated whether temporal isotopic variation in consumers may also reflect environmental baselines through trophic propagation. We modeled the monthly variation in carbon and nitrogen isotope values in whole blood of four insectivorous bat species occupying different foraging niches in southern Spain. We found a common pattern of isotopic variation independent of feeding habits, with an overall change as large as or larger than one trophic step. Physiological changes related to reproduction or to fat deposition prior to hibernation had no effect on isotopic variation, but juvenile bats had higher δ13C and δ15N values than adults. Aridity was the factor that best explained isotopic variation: bat blood became enriched in both 13C and 15N after hotter and/or drier periods. Our study is the first to show that consumers in terrestrial ecosystems reflect seasonal environmental dynamics in their isotope values. We highlight the danger of misinterpreting stable isotope data when not accounting for seasonal isotopic baselines in food web studies. Understanding how environmental seasonality is integrated in animals' isotope values will be crucial for developing reliable methods to use stable isotopes as dietary tracers.

δ15N value does not reflect fasting in mysticetes

The finding that tissue δ¹⁵N values increase with protein catabolism has led researchers to apply this value to gauge nutritive condition in vertebrates. However, its application to marine mammals has in most occasions failed. We investigated the relationship between δ¹⁵N values and the fattening/fasting cycle in a model species, the fin whale, a migratory capital breeder that experiences severe seasonal variation in body condition. We analyzed two tissues providing complementary insights: one with isotopic turnover (muscle) and one that keeps a permanent record of variations in isotopic values (baleen plates). In both tissues δ¹⁵N values increased with intensive feeding but decreased with fasting, thus contradicting the pattern previously anticipated. The apparent inconsistency during fasting is explained by the fact that a) individuals migrate between different isotopic isoscapes, b) starvation may not trigger significant negative nitrogen balance, and c) excretion drops and elimination of ¹⁵N-depleted urine is minimized. Conversely, when intensive feeding is resumed in the northern grounds, protein anabolism and excretion start again, triggering ¹⁵N enrichment. It can be concluded that in whales and other mammals that accrue massive depots of lipids as energetic reserves and which have limited access to drinking water, the δ¹⁵N value is not affected by fasting and therefore cannot be used as an indicatior of nutritive condition.

Evidence for a (15)N positive excursion in terrestrial foodwebs at the Middle to Upper Palaeolithic transition in south-western France: Implications for early modern human palaeodiet and palaeoenvironment

The Middle to Upper Palaeolithic transition around 35,000 years ago coincides with the replacement of Neanderthals by anatomically modern humans in Europe. Several hypotheses have been suggested to explain this replacement, one of them being the ability of anatomically modern humans to broaden their dietary spectrum beyond the large ungulate prey that Neanderthals consumed exclusively. This scenario is notably based on higher nitrogen-15 amounts in early Upper Palaeolithic anatomically modern human bone collagen compared with late Neanderthals. In this paper, we document a clear increase of nitrogen-15 in bone collagen of terrestrial herbivores during the early Aurignacian associated with anatomically modern humans compared with the stratigraphically older Châtelperronian and late Mousterian fauna associated with Neanderthals. Carnivores such as wolves also exhibit a significant increase in nitrogen-15, which is similar to that documented for early anatomically modern humans compared with Neanderthals in Europe. A shift in nitrogen-15 at the base of the terrestrial foodweb is responsible for such a pattern, with a preserved foodweb structure before and after the Middle to Upper Palaeolithic transition in south-western France. Such an isotopic shift in the terrestrial ecosystem may be due to an increase in aridity during the time of deposition of the early Aurignacian layers. If it occurred across Europe, such a shift in nitrogen-15 in terrestrial foodwebs would be enough to explain the observed isotopic trend between late Neanderthals and early anatomically modern humans, without any significant change in the diet composition at the Middle to Upper Palaeolithic transition.

Desert tortoise (Gopherus agassizii) dietary specialization decreases across a precipitation gradient

We studied the plant resource use between and within populations of desert tortoise (Gopherus agassizii) across a precipitation gradient in the Sonoran Desert of Arizona. The carbon and nitrogen stable isotope values in animal tissues are a reflection of the carbon and nitrogen isotope values in diet, and consequently represent a powerful tool to study animal feeding ecology. We measured the δ¹³C and δ¹⁵N values in the growth rings on the shells of tortoises in different populations to characterize dietary specialization and track tortoise use of isotopically distinct C₄/CAM versus C₃ plant resources. Plants using C₃ photosynthesis are generally more nutritious than C₄ plants and these trait differences can have important growth and fitness consequences for consumers. We found that dietary specialization decreases in successively drier and less vegetated sites, and that broader population niche widths are accompanied by an increase in the dietary variability between individuals. Our results highlight how individual consumer plant resource use is bounded under a varying regime of precipitation and plant productivity, lending insight into how intra-individual dietary specialization varies over a spatial scale of environmental variability.

Stable isotope analysis in primatology: a critical review

Stable isotope analysis has become an important tool in ecology over the last 25 years. A wealth of ecological information is stored in animal tissues in the relative abundances of the stable isotopes of several elements, particularly carbon and nitrogen, because these isotopes navigate through ecological processes in predictable ways. Stable carbon and nitrogen isotopes have been measured in most primate taxonomic groups and have yielded information about dietary content, dietary variability, and habitat use. Stable isotopes have recently proven useful for addressing more fine-grained questions about niche dynamics and anthropogenic effects on feeding ecology. Here, we discuss stable carbon and nitrogen isotope systematics and critically review the published stable carbon and nitrogen isotope data for modern primates with a focus on the problems and prospects for future stable isotope applications in primatology.

Carbon and nitrogen isotopic survey of northern peruvian plants: baselines for paleodietary and paleoecological studies

The development of isotopic baselines for comparison with paleodietary data is crucial, but often overlooked. We review the factors affecting the carbon (δ(13)C) and nitrogen (δ(15)N) isotopic compositions of plants, with a special focus on the carbon and nitrogen isotopic compositions of twelve different species of cultivated plants (n = 91) and 139 wild plant species collected in northern Peru. The cultivated plants were collected from nineteen local markets. The mean δ(13)C value for maize (grain) was -11.8±0.4 ‰ (n = 27). Leguminous cultigens (beans, Andean lupin) were characterized by significantly lower δ(15)N values and significantly higher %N than non-leguminous cultigens. Wild plants from thirteen sites were collected in the Moche River Valley area between sea level and ∼4,000 meters above sea level (masl). These sites were associated with mean annual precipitation ranging from 0 to 710 mm. Plants growing at low altitude sites receiving low amounts of precipitation were characterized by higher δ(15)N values than plants growing at higher altitudes and receiving higher amounts of precipitation, although this trend dissipated when altitude was >2,000 masl and MAP was >400 mm. For C(3) plants, foliar δ(13)C was positively correlated with altitude and precipitation. This suggests that the influence of altitude may overshadow the influence of water availability on foliar δ(13)C values at this scale.