Stable isotope analysis of Pacific rat (Rattus exulans) from archaeological sites in Mangareva (French Polynesia): The use of commensal species for understanding human activity and ecosystem change

Stable carbon and nitrogen isotope analysis was applied to archaeological specimens of the commensal Pacific rat (Rattus exulans) to investigate nutrient fluxes in prehistoric socio-ecosystems on Mangareva (Gambier Islands) and their implications for anthropogenic environmental change. The Pacific rat – ubiquitous in Polynesian archaeological sites – is characterised by low dietary selectivity and a limited home range, making it an ideal candidate for assessing changes in island food webs. Temporal trends in diet-derived bone collagen δ¹³C and δ¹⁵N values are assessed from three sites: The Onemea Site, Taravai Island (TAR-6), Nenega-iti Rockshelter, Agakauitai Island (AGA-3) and Kitchen Cave Rockshelter, Kamaka Island (KAM-1). An overall trend of decreasing δ¹⁵N values in rat bone collagen over time reflects archipelago-wide changes to island socio-ecosystems most likely resulting from seabird population declines. Differences in site function and human activity may have also influenced local rat dietary patterns. Stable isotope analysis of the Pacific rat provides a low-impact line of evidence towards the reconstruction of human-centred food webs and the flow of nutrients within island socio-ecosystems.     

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

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

Isotopic evidence for Middle Horizon to 16th century camelid herding in the Osmore Valley,Peru

Archaeological and zooarchaeological data indicate that camelid pastoralism was a subsistence and economic mainstay of Middle Horizon and more recent cultures in the Osmore region of southern Peru. However, it is not known whether camelids were primarily herded in highland puna pastures or near lower elevation sites in the middle valley or along the coast. This research examines the elevation of archaeological camelid herding in the Osmore Valley using stable isotope analysis. Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios were measured on 28 archaeological camelid bone samples from the Middle Horizon sites of Cerro Baúl and Cerro Mejía, the Late Intermediate site of Yaral and the late pre‐Hispanic to Colonial period site of Torata Alta. Twenty‐three archaeological camelids have δ¹³C and δ¹⁵N values similar to five modern camelids maintained in highland puna pastures. In contrast, three camelids from the high status Wari site of Cerro Baúl, and two from Yaral have unexpectedly high δ¹³C and/or δ¹⁵N values outside the expected range for camelids pastured in highland puna habitats. The results may be explained by differences in foddering practices, altitudinal herding range or climatic conditions. Strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) were also assessed to infer pasture elevation using the camelid remains from Cerro Baúl (n = 11). One individual in this sub‐sample exhibits a non‐local ⁸⁷Sr/⁸⁶Sr value indicative of an origin in the highland puna region east or south of Lake Titicaca. It was not possible to further distinguish between camelids herded in lower to middle elevation habitats outside the Lake Titicaca basin using ⁸⁷Sr/⁸⁶Sr values. This study suggests that multiple isotope proxies may be used to identify animals primarily pastured in lowland coastal versus highland puna (> 4000 masl (meters above sea level)) habitats, but are less useful at distinguishing between animals pastured in lower to middle elevation settings. Copyright © 2010 John Wiley & Sons, Ltd.     

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

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

Modeling Breastfeeding and Weaning Practices (BWP) on the Coast of Northern Chile's Atacama Desert During the Formative Period

Stable isotope analysis of bone collagen is frequently employed as a means of studying the breastfeeding and weaning practices (BWP) of archaeological populations. Such studies are strengthened greatly through the application of statistical models that permit precise and model-bound estimates of weaning age, duration, trophic enrichment, and the isotopic characterization of supplementary foods. Here we present the result of a stable isotope (δ¹⁵N) and Bayesian computational modeling study of bone collagen from human subadults from two coastal cemetery sites located near the mouth of the River Loa in the Atacama Desert. Recent bioarchaeological and paleodemographic research on remains from these marine hunter-gatherer sites, which are contemporary with the Formative Period (1500 BC–AD 400), has found evidence for notably elevated rates of female fertility. Ultimately, we argue that the modeled BWP parameters, which indicate the early introduction of supplementary foods, support an argument of high fertility as gleaned from the bioarchaeological evidence, and that these results provide novel insights into the child-rearing practices of the coastal populations of the Atacama. Indeed, these populations would have seemed to have developed a set of BWP that carefully balanced the biological and economic production/reproduction of the community.     

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

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

Stable hydrogen isotopes of bone collagen in palaeodietary and palaeoenvironmental reconstruction

The stable hydrogen isotope ratios (δD) of bone collagen in archaeological human and animal samples demonstrate a trophic level effect, with increasing δD from herbivores to omnivores to humans, in steps of 10–30‰. In addition the archaeological sites studied (Yarnton, Eton Rowing Lake, Danebury Environs–Suddern Farm, and Windmill Hill in the UK, Balatonszárszó in Hungary, and Huari in Peru) demonstrate geographical variation in δD. The detection of manuring in prehistory by comparison of δ¹⁵N to δD values in humans and a local herbivore (cattle) is also considered. This work is the first to measure δD in a large number and range of archaeological samples, with several animal species and humans. It demonstrates unequivocally that δD is different between species in ancient material, increasing from herbivores to omnivores to carnivores.     

Stable isotopes and human diet in central western Argentina

Central western Argentina is the southern boundary of prehispanic maize in the archaeological record. This paper explores the stable isotope information from human bone (δ¹³C, from collagen and δ¹³C from apatite) and tooth (δ¹³C from enamel) samples in order to characterize the temporal and spatial trends of these isotopes and to understand them in terms of human diet. We analyzed 104 human individuals from the last 6000 years. Using the Kellner and Schoeninger (2007) model the results shows a high variation in human diet with few human individuals with a notably high significance of C₄ plants (probably maize) as an energy source and these samples have a chronology around ca. 1000 years BP. On the other hand a high variation in an individual’s dietary life history is shown by differences between δ¹³C collagen, apatite and enamel.     

Carbon and nitrogen isotope composition of natural pastures in the dry Puna of Argentina: a baseline for the study of prehistoric herd management strategies

This study represents an isotopic survey of modern plants developed to establish baseline isotopic values in order to explore prehistoric herd management strategies employed by the South American camelid herders that occupied the southern Andean highlands during the past 3000 years. We present carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic compositions of natural pastures collected from different plant communities along an altitudinal gradient in the dry Puna of Argentina. Our results show that C₃ plants are the most abundant along the whole altitudinal gradient and that C₃ and C₄ plants exhibit a differential distribution, the latter being less abundant in those sites located above 3900?meters above sea level (masl). At the same time, plants growing at low-altitude sites with low water availability exhibit higher δ¹⁵N values than plants growing at high-altitude sites with higher water availability. These results explain the negative correlation found between altitude and South American camelid bone collagen δ¹³C and δ¹⁵N values published in previous studies. This work represents a fundamental step towards the building of an isotopic ecology for the dry Puna area with the ultimate goal to explore herd management strategies employed by human groups in the past. In this sense, modern plant and South American camelid tissue isotopic compositions would provide a frame of reference to interpret isotopic compositions measured on archaeofaunal remains recovered at pastoral sites, with the aim to explore mobility and pastureland use by prehistoric herders.     

Stable isotope analysis on human remains from the final Early Holocene in the southern Puna of Argentina: The case of Peñas de las Trampas 1.1

In this work are presented the results of isotopic analyses made on bone remains of human individuals (n?=?6) from the southern Puna of Argentina dated to the final Early Holocene (ca. 8230–8000 BP). They were found in structures located in Peñas de las Trampas 1.1, a rockshelter at 3582 m.a.s.l. in Antofagasta de la Sierra, in the southern Argentinian Puna. They contain multiple secondary burials. Bone fragments were recovered from at least six individuals, three in each structure. Stable isotopes of Carbon (δ¹³C) and Nitrogen (δ¹⁵N) analysis were aimed at defining aspects related to the palaeodiet of the six individuals within the palaeo-economic subsistence spectrum typical of hunter–gatherers. It is worth noting that these human remains are among the earliest from North-Western Argentina, where funeral practices are related with the transportation of certain anatomical parts. The palaeodietary inference considers, on the one hand, the extreme aridity of this geographical area and its impact on the isotopic ecology. And, on the other, it takes into account the fact that four of the six individuals under study were breastfed infants. The results are in agreement with the expected values of the period, which has been characterized as the beginning of the arid Altithermal.     

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

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

Calcium isotopes in archaeological bones and their relationship to dairy consumption

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

Introducing δSr analysis in archaeology: a demonstration of the utility of strontium isotope fractionation in paleodietary studies

Isotopic methods are widely used in archaeology to investigate paleodiet. Here, we present a new method to identify trophic level in archaeological human populations and to investigate paleodiet. We demonstrate that strontium isotope compositions (reported as δ^88/86Sr) vary in a mass-dependent manner with increasing trophic level and can elucidate paleodiet in archaeological human populations. We present new mass-dependent strontium isotope data from tooth enamel and bone from individuals buried during the Late Intermediate Period (c. AD 1000–1300) in the large cemeteries of Chiribaya Alta, Chiribaya Baja, San Gerónimo, and El Yaral in the Ilo and Moquegua Valleys of southern Peru. We compare these data to radiogenic strontium isotope data (⁸⁷Sr/⁸⁶Sr) and light stable isotope data (δ¹⁵N_col and δ¹³C_col) from the same individuals to investigate geologic variability in strontium sources as well as marine food consumption among the Chiribaya. Our results demonstrate the utility of measurements of strontium isotope fractionation as a new tool for archaeological investigation of paleodiet. Importantly, this new technique can be used to generate paleodietary (δ^88/86Sr) and paleomobility (⁸⁷Sr/⁸⁶Sr) data from the same specimen, minimizing destructive analyses of invaluable archaeological material, and provides a new way to examine paleodiet through hydroxyapatite, which is particularly important when collagen is poorly preserved.     

A Simple(R) Model to Predict the Source of Dietary Carbon in Individual Consumers

Quantitative individual human diet reconstruction using isotopic data and a Bayesian approach typically requires the inclusion of several model parameters, such as individual isotopic data, isotopic and macronutrient composition of food groups, diet‐to‐tissue isotopic offsets and dietary routing. In an archaeological context, sparse data may hamper a widespread application of such models. However, simpler models may be proposed to address specific archaeological questions. As a consequence of the intake of marine foods, individuals from the first century ad Roman site of Herculaneum showed well‐defined bone collagen radiocarbon age offsets from the expected terrestrial value. Taking as reference these radiocarbon offsets and using as model input stable isotope data (δ¹³C and δ¹⁵N), the performance of two Bayesian mixing model instances (routed and concentration‐dependent model versus non‐routed and concentration‐independent) was compared to predict the carbon contribution of marine foods to bone collagen. Predictions generated by both models were in good agreement with observed values. The model with higher complexity showed only a slightly better performance in terms of accuracy and precision. This demonstrates that under similar circumstances, a simple Bayesian approach can be applied to quantify the carbon contribution of marine foods to human bone collagen.     

Stable isotopes and diet at Ancient Kerma,Upper Nubia (Sudan)

Carbon and nitrogen stable isotope values were measured from bone collagen extracted from archaeological Nubian human (n = 54) and faunal (n = 61) populations from the site of Kerma, Sudan. Collagen suitable for isotopic analysis was extracted from 22 faunal and 48 human samples from the Eastern cemetery site, dated to the Middle Kerma (c. 2050–1750 BC) and Classic Kerma (c. 1750–1500 BC) periods respectively. The isotopic data indicate that the human dietary regimen included a mix of C₃ and C₄ plant-derived components, with a larger C₄ component than previously reported in archaeological Egyptian Nile Valley populations. Elevated δ¹⁵N values are attributed to consumption of dietary resources from a ¹⁵N-enriched terrestrial ecosystem. The faunal isotope data also indicate the consumption of C₃ and C₄ plants. The large range of δ¹³C values measured in both the human and faunal samples supports previous work suggesting that a significant portion of the populations buried at Kerma may have originated elsewhere, further confirming the Nile Valley as a major corridor for population movement in the region.     

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

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

Late Holocene Historical Ecology: The Timing of Vertebrate Extirpation on Crooked Island,Commonwealth of The Bahamas

We report eight new accelerator-mass spectrometer (AMS) radiocarbon (¹⁴C) dates performed directly on individual bones of extirpated species from Crooked Island, The Bahamas. Three dates from the hutia (Geocapromys ingrahami), recovered from a culturally derived bone assemblage in McKay's Bluff Cave (site CR-5), all broadly overlap from AD 1450 to 1620, which encompasses the time of first European contact with the Lucayan on Crooked Island (AD 1492). Marine fish and hutia dominate the bone assemblage at McKay's Bluff Cave, shedding light on vertebrate consumption by the Lucayans just before their demise. A fourth AMS ¹⁴C date on a hutia bone, from a non-cultural surface context in Crossbed Cave (site CR-25), is similar (AD 1465 to 1645) to those from McKay's Bluff Cave. From Pittstown Landing (site CR-14), an open coastal archaeological site, a femur of the Cuban crocodile (Crocodylus rhombifer) yielded an AMS ¹⁴C date of AD ～1050–1250, which is early in the Lucayan cultural sequence. From a humerus in a non-cultural surface context in 1702 Cave (site CR-26), we document survival of the Cuban crocodile on Crooked Island until AD ～1300–1400, which is several hundred years later than the well-documented extinction of Cuban crocodiles on Abaco in the northern Bahamas. We lack a clear explanation of why Cuban crocodiles likely survived longer on Crooked Island than on a larger Bahamian island such as Abaco. One AMS ¹⁴C date on Crooked Island's extinct, undescribed species of tortoise (Chelonoidis sp.) from 1702 Cave is BC 790 to 540 (2740 to 2490 cal BP), which is ～1500–1700 years prior to human arrival. A second AMS ¹⁴C date, on a fibula of this tortoise from McKay's Bluff Cave, is AD 1025 to 1165, thereby demonstrating survival of this extinct species into the period of human occupation.     

Dietary changes and millet consumption in northern France at the end of Prehistory: Evidence from archaeobotanical and stable isotope data

Diachronic changes of dietary human habits between the Neolithic and the Bronze Age are mainly identified through archaeological artefacts and archaeozoological and archaeobotanical studies. This paper aims to demonstrate the importance of a multi-disciplinary approach for palaeodietary studies and to identify the food changes between Neolithic and Bronze Age human groups in northern France. These changes are probably linked to the introduction of new crops, such as millet, and the use of stable isotope analysis on bones and teeth proves to be an effective method for assessing the role of this specific cereal in the diet and the economy. Stable isotope analyses were performed on bone and tooth collagen and apatite from eight humans and five domestic animals from a Late Bronze Age site (LBA; Barbuise; 15th–13th c. BC; Aube). The studied corpus is compared with isotopic data from human and animal bones from a nearby Neolithic site (Gurgy; 5th mill. BC; Yonne) and regional Neolithic to Iron sites located in northern France. Moreover, Barbuise data are supplemented by information from an important archaeobotanical study carried out on 21 LBA and Early Iron Age sites in the region. Neolithic and LBA human collagen isotopic ratios (δ¹³C, δ¹⁵N) differ statistically, as do those of some animals. Carbon isotopic ratios of human apatite corroborate collagen results indicating the consumption of ¹³C enriched food by LBA humans and animals compared to Neolithic samples. The high number of occurrences of plant remains in the Bronze Age settlements near the site points to the consumption of C₄ plants, such as millet, and would account for these results.     

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

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

Intra‐individual variation in stable carbon (δ13C) and nitrogen (δ15N) isotopes in mandibles of modern caribou of Qamanirjuaq (Rangifer tarandus groenlandicus) and Banks Island (Rangifer tarandus pearyi): Implications for tracing seasonal and temporal changes in diet

Intra‐individual variations in carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope measurements of dentine collagen in ungulate teeth can be related to diet and environmental changes at different periods during the life of the animal. A protocol of serial sampling of first, second and third molar roots was applied to modern caribou (17–27 months old) of the Qamanirjuaq herd (Rangifer tarandus groenlandicus), Canada. Based on a previous study, we predicted that M2 would reflect winter, M3 summer and M1 a complete year in terms of the isotopic record. Relatively high δ¹⁵N values (ca. 6 to 8‰), previously attributed to winter stress, were found in different molars of different specimens, reflecting a period of growth between April 1966 to April 1967. Previous results on other teeth from the same population confirmed that a high δ¹⁵N_coll value signal corresponded to the winter of 1966/67. This temporary increase in δ¹⁵N value was probably linked to diet and/or environmental change. Collagen from M1 reflects the first winter whereas M2 and M3 reflect the second winter of life of young caribou. A longer time record including summer is represented by the bone collagen of the mandible. Results obtained on molar roots and mandible bone of the modern caribou of Banks Island herd (Rangifer tarandus pearyi) confirmed this seasonal record. Such collagen isotopic analysis on M1, M2 and M3 roots and jawbone can be applied to reindeer found in archaeological sites. Mandibles retaining deciduous premolars are preferable to avoid the possible loss of the winter tooth signal observed in animals older than 2 years. Copyright © 2010 John Wiley & Sons, Ltd.