Nitrogen Isotope Data Research Articles

High intraspecific variability in the diet of a deep-sea nematode: Stable isotope and fatty acid analyses of Deontostoma tridentum on Chatham Rise, Southwest Pacific

Small deep-sea organisms may exhibit a high degree of intraspecific variability in diet due to their ability to exploit a wide range of food sources and patchiness in food availability. Trophic interactions of small deep-sea benthic organisms, however, remain poorly understood. Here we describe spatial variation in diet/trophic level of the common deep-sea nematode Deontostoma tridentum on Chatham Rise, Southwest Pacific, using carbon and nitrogen stable isotope and fatty acid analyses. We also analysed sediment organic matter (SOM) and compared the isotopic composition of D. tridentum to other benthic and suprabenthic macrofaunal taxa with a variety of feeding modes. Variability in D. tridentum δ13C and δ15N signatures was high both among sites and within a single site on the southern flank of Chatham Rise. Among-site variation in SOM δ13C signatures was not sufficient to explain variation in nematode isotopic signatures. The presence of a positive correlation between δ13C and δ15N signatures of D. tridentum (both among and within sites) could suggest that differences in trophic level is the cause behind this variation. Nitrogen isotope data suggest the presence of 1–3 trophic levels in this species, which may reflect differences in prey availability, nematode body size, or habitat (benthic versus epizoic). Nematode δ15N values exceeded those of all other taxa we investigated, including other predators, but reasons for this enrichment remain unclear. The fatty acid composition of D. tridentum did not vary substantially between sites and was characterised by relatively high levels of 18:1n9 (15–20%) and polyunsaturated fatty acids (PUFAs; ~22%). Although limited inferences can be made based on fatty acid composition due to the potential impacts of non-dietary factors, high levels of PUFAs indicate that D. tridentum represents a good source of these essential nutrients to higher trophic levels. In conclusion, our results show that (1) some deep-sea organisms exhibit a high degree of intraspecific variability in diet, and (2) nematodes may be an important source of PUFAs for larger animals in deep-sea environments, where the quality of SOM is low.

Lombards on the move--an integrative study of the migration period cemetery at Szólád, Hungary.

In 2005 to 2007 45 skeletons of adults and subadults were excavated at the Lombard period cemetery at Szólád (6th century A.D.), Hungary. Embedded into the well-recorded historical context, the article presents the results obtained by an integrative investigation including anthropological, molecular genetic and isotopic (δ15N, δ13C, 87Sr/86Sr) analyses. Skeletal stress markers as well as traces of interpersonal violence were found to occur frequently. The mitochondrial DNA profiles revealed a heterogeneous spectrum of lineages that belong to the haplogroups H, U, J, HV, T2, I, and K, which are common in present-day Europe and in the Near East, while N1a and N1b are today quite rare. Evidence of possible direct maternal kinship was identified in only three pairs of individuals. According to enamel strontium isotope ratios, at least 31% of the individuals died at a location other than their birthplace and/or had moved during childhood. Based on the peculiar 87Sr/86Sr ratio distribution between females, males, and subadults in comparison to local vegetation and soil samples, we propose a three-phase model of group movement. An initial patrilocal group with narrower male but wider female Sr isotope distribution settled at Szólád, whilst the majority of subadults represented in the cemetery yielded a distinct Sr isotope signature. Owing to the virtual absence of Szólád-born adults in the cemetery, we may conclude that the settlement was abandoned after approx. one generation. Population heterogeneity is furthermore supported by the carbon and nitrogen isotope data. They indicate that a group of high-ranking men had access to larger shares of animal-derived food whilst a few individuals consumed remarkable amounts of millet. The inferred dynamics of the burial community are in agreement with hypotheses of a highly mobile lifestyle during the Migration Period and a short-term occupation of Pannonia by Lombard settlers as conveyed by written sources.

Climate. Greenland deglaciation puzzles.

Nitrogen isotope data help to resolve puzzling observations during the last deglaciation [Also see Report by Buizert et al. ]

Isotope paleoecology of episodic mid-to-late Holocene bison population expansions in the Southern Plains, U.S.A.

We used a XAD-purified AMS radiocarbon method to date 62 bison specimens from different contexts on the very southern extent of the Great Plains of North America to produce a precise chronology of bison population expansions spanning the last 6000 years. Sixty-one of these samples provide stable carbon and nitrogen isotope data indicating relative temperature and moisture conditions during intervals defined by the presence of bison within this time span. This chronology indicates climatic conditions favorable to bison were present in the greater central Texas area, including the uplifted Edwards Plateau and extending to the Coastal Plain during periods from ∼5955 to 5815, ∼3290 to 3130, 2700 to 2150, and 650 to 530 cal BP. However, isotope results suggest climatic conditions differed for each period. The earliest “Calf Creek” period was characterized by cool but dry conditions, the later “Late Archaic 1 & 2” periods were increasingly warmer and wetter, and the latest “Toyah” period was cooler and drier than the Late Archaic periods, but warmer and wetter than Calf Creek. Both the Calf Creek and Toyah periods had higher variability within these overall trends. Comparison with regional records suggests that these periods represent variation within generally cool–dry climates. Human adaptive response to increased bison availability resulted in significant cultural changes across all four periods.

Isotopic studies of the diet of the people of the coast of British Columbia.

In 1982, Chisholm et al. used δ(13) C data for human burials from shell midden sites widely distributed on the coast of British Columbia (BC) to show the extreme dependence of these individuals on high trophic level marine consumers, principally salmon and marine mammals. Here, we present previously unpublished analyses of δ(15) N for some of the same individuals as well as δ(13) C data for additional individuals. Nitrogen isotope data show that the diet was dominated by high trophic level marine fauna including carnivorous fish and marine mammals. Although most burials were found in shell middens, marine mollusks made up of only a minor component of diet. The data for δ(13) C demonstrate that terrestrial faunal foods are undetectable in the diet of the majority of individuals, and seldom constitute more than 10% of the dietary protein of individuals living on the coast although terrestrial fauna were widely available as a potential source of protein. This dietary pattern of exclusion of land-based animals from their diet persisted for almost 6,000 years along a wide expanse of coastline. In contrast, people from the BC interior (100 km or more from the coast) consumed a mixed diet of terrestrial and marine foods including spawning salmon.

Interlaboratory assessment of nitrous oxide isotopomer analysis by isotope ratio mass spectrometry and laser spectroscopy: current status and perspectives.

In recent years, research and applications of the N2O site-specific nitrogen isotope composition have advanced, reflecting awareness of the contribution of N2O to the anthropogenic greenhouse effect, and leading to significant progress in instrument development. Further dissemination of N2O isotopomer analysis, however, is hampered by a lack of internationally agreed gaseous N2O reference materials and an uncertain compatibility of different laboratories and analytical techniques. In a first comparison approach, eleven laboratories were each provided with N2O at tropospheric mole fractions (target gas T) and two reference gases (REF1 and REF2). The laboratories analysed all gases, applying their specific analytical routines. Compatibility of laboratories was assessed based on N2O isotopocule data for T, REF1 and REF2. Results for T were then standardised using REF1 and REF2 to evaluate the potential of N2O reference materials for improving compatibility between laboratories. Compatibility between laboratories depended on the analytical technique: isotope ratio mass spectrometry (IRMS) results showed better compatibility for δ(15)N values, while the performance of laser spectroscopy was superior with respect to N2O site preference. This comparison, however, is restricted by the small number of participating laboratories applying laser spectroscopy. Offset and two-point calibration correction of the N2O isotopomer data significantly improved the consistency of position-dependent nitrogen isotope data while the effect on δ(15)N values was only minor. The study reveals that for future research on N2O isotopocules, standardisation against N2O reference material is essential to improve interlaboratory compatibility. For atmospheric monitoring activities, we suggest N2O in whole air as a unifying scale anchor.

Stable isotope composition of human fingernails from Slovakia

Stable isotope composition of human fingernails has proven to be useful for documenting human dietary information and geographical patterns in archeological, forensic, anthropological and biological studies. Therefore, it is of interest to detect all factors influencing the stable isotopic composition in the certain regions in the world.Carbon and nitrogen isotope data of human fingernail keratin from 52 individuals from Slovakia were reported in this study. The online combustion and continuous flow isotope-ratio mass spectrometer Delta V Advantage was used for δ13C and δ15N analysis of fingernail keratin samples from 24 vegetarian and 28 omnivorous individuals.A group of people with frequent meat consumption showed enrichment in 13C and 15N isotopes in fingernails. A similar trend was observed with increasing seafood in an individual's diet. Moreover a significant difference was revealed between smokers and nonsmokers for both δ13C and δ15N values. These data were compared to previously published δ13C and δ15N fingernail values from across the globe.This study brings new information on the stable isotope signature of individuals from Slovakia and characterizes the Central European region for the first time. The stable isotope composition of fingernails is influenced by the frequency of meat and seafood consumption as well as smoking.

Evidence for benthic–pelagic food web coupling and carbon export from California margin bamboo coral archives

Abstract. Deep-sea bamboo corals (order Gorgonacea, family Isididae) are known to record changes in water mass chemistry over decades to centuries. These corals are composed of a two-part skeleton of calcite internodes segmented by gorgonin organic nodes. We examine the spatial variability of bamboo coral organic node 13C/12C and 15N/14N from 13 bamboo coral specimens sampled along the California margin (37–32° N, 792–2136 m depth). Radiocarbon analyses of the organic nodes show the presence of the anthropogenic bomb spike, indicating the corals utilize a surface-derived food source (pre-bomb D14C values of ∼−100‰, post-bomb values up to 82‰). Carbon and nitrogen isotope data from the organic nodes (δ13C = −15.9‰ to −19.2‰; δ15N = 13.8‰ to 19.4‰) suggest selective feeding on surface-derived organic matter or zooplankton. A strong relationship between coral δ15N and habitat depth indicates a potential archive of changing carbon export, with decreased δ15N values reflecting reduced microbial degradation (increased carbon flux) at shallower depths. Using four multi-centennial-length coral records, we interpret long-term δ15N stability in the California Current. Organic node δ15C values record differences in carbon isotope fractionation dictated by nearshore vs. offshore primary production. These findings imply strong coupling between primary production, pelagic food webs, and deep-sea benthic communities.

Stable isotopes complement focal individual observations and confirm dietary variability in reddish-gray mouse lemurs (Microcebus griseorufus) from southwestern Madagascar.

We examine the ecology of reddish-gray mouse lemurs from three habitats at Beza Mahafaly Special Reserve using focal follows and stable carbon and nitrogen isotope data. Focal observations indicate dietary differences among habitats as well as sexes and seasons. Both sexes consume more arthropods during the rainy season but overall, females consume more sugar-rich exudates and fruit than males, and individuals from riparian forest consume fewer arthropods and more fruit than those in xeric or dry forest. We ask whether these observations are isotopically detectable. Isotope data support differences between seasons and sexes. Nitrogen isotope values are higher during the rainy season when lemurs consume more arthropods, and higher in males than females, particularly during the dry season. However, differences among populations inferred from focal observations are not fully supported. Lemurs from riparian forest have lower isotope values than those in xeric scrub, but isotope data suggest that lemurs from the dry forest eat the least animal matter and that focal observations overestimated dry forest arthropod consumption. Overall, our results suggest that observational and isotopic data are complementary. Isotope data can be obtained from a larger number of individuals and can quantify ingestion of animal matter, but they apparently cannot quantify the relative consumption of different sugar-rich foods. Combined focal and isotope data provide valuable insight into the dietary constraints of reddish-grey mouse lemurs, with implications for their vulnerability to future habitat change.

Nitrogen isotopic response of prokaryotic and eukaryotic phytoplankton to nitrate availability in Sargasso Sea surface waters

Taxon‐specific nitrogen (N) isotope data from the summertime Sargasso Sea have previously suggested reliance of prokaryotic phytoplankton on regenerated N but a greater importance of nitrate assimilation for eukaryotic phytoplankton. To investigate this further, particles collected in the summer from ∼ 100 m at the Bermuda Atlantic Time‐series Study site were incubated in particle‐free, unamended surface seawater (from 4 m and 30 m) with measured ambient nitrate and ammonium concentrations. Preincubation and postincubation particles were sorted using flow cytometry, and the δ15N of separated prokaryotic and eukaryotic phytoplankton was analyzed. In July 2009 and 2010, nitrate was undetectable throughout the euphotic zone (the upper ∼ 100 m). The δ15N of prokaryotic biomass was initially low and remained low upon incubation, with one exception out of six. Preincubation eukaryotic δ15N was higher than or similar to prokaryotic δ15N and decreased or remained low after incubation. These data confirm the expectation that, in nitrate‐deplete water, all phytoplankton shift toward a low δ15N characteristic of recycled N assimilation. In June 2010, the euphotic zone nitrate concentration was anomalously high (∼ 1 µmol L−1), and the δ15N of all populations varied as a function of depth, with highest δ15N in the surface where nitrate was lowest. After incubation in surface water, the δ15N of all sorted phytoplankton increased, suggesting nitrate assimilation by all groups, including Prochlorococcus, the nitrate assimilatory capabilities of which have been debated. This study supports the use of the δ15N of sorted phytoplankton as an indicator of the dominant N source fueling their growth.

Dental calculus is not equivalent to bone collagen for isotope analysis: a comparison between carbon and nitrogen stable isotope analysis of bulk dental calculus, bone and dentine collagen from same individuals from the Medieval site of El Raval (Alicante, Spain)

Palaeodietary reconstruction using the carbon and nitrogen isotope values of bone and dentine collagen is a well-established method and the biochemical processes involved are well known. Researchers have recently explored using bulk samples of dental calculus as a substitute for bone and dentine collagen in dietary analyses, because calculus can be sampled without causing damage to the teeth, and may be useful in situations where more destructive analyses are not possible, or where collagen is poorly preserved. Several questions remain about the use of bulk calculus as a source of carbon and nitrogen isotope data, however. It is not yet clear how much of an individual's life span dental calculus represents, what portions of the diet it records, and how diagenesis effects the carbon and nitrogen isotope values of this material. Most importantly, there have been no comparative studies of collagen and calculus isotope values, which are necessary to establish the value of bulk calculus as a source of accurate isotope values. Here we report the comparison of carbon and nitrogen stable isotope analyses of bulk calculus to those from bone and dentine collagen. These analyses have been performed on individuals from the El Raval Mudéjar Medieval Cemetery (Eastern Iberia, 15th century A.D.). Although calculus isotope values may be broadly similar to expected values at the population level, we report here no correlation between collagen and bulk dental calculus values at the individual level. As a result, we recommend that carbon and nitrogen analysis on bulk dental calculus should only be used as a last resource archaeological dietary marker, if at all.

Dental health, diet, and social transformations in the Bronze Age: Comparative analysis of pastoral populations in northern Kazakhstan

Comparative analyses of human health and diet are often undertaken for consecutive periods of time which exhibit different social formations or material culture. The aim of this research was to test the link between social transformations and corollary shifts in health or diet. Therefore, oral health and dietary intake were examined in successive Bronze Age periods in central Eurasia with very different patterns of settlement and scales of interaction. Researchers have posited that these periods are evidence of an economic shift from agro-pastoral to pastoral patterns of subsistence. Populations from two sites in northern Kazakhstan (52°10′N, 64°32′E; 52°32′N, 62°23′E) were investigated in terms of dental caries, calculus, abscesses, ante-mortem tooth loss and periodontal disease. The results of this study indicate that the types of dental pathological conditions present stayed relatively uniform over time, suggesting similarities in dietary intake for populations at the sites of Bestamak (2032–1639 cal BC) and Lisakovsk (1860–1680 cal BC). The dietary intake of these communities is indicative of a noncariogenic diet with a high protein content and lack of carbohydrates. These findings conform to general patterns for pastoral societies and are consistent with stable carbon and nitrogen isotopic data. While they types of pathological conditions were similar, the severity of these lesions decreased in the later period. Comparatively more pronounced frequencies of pathological conditions during the earlier period are attributed to multiple etiologies including different patterns of consumption, dental cleaning behaviors, or stress. While the archaeological record indicates broad shifts in settlement patterns, demography, and mortuary rituals from the Middle to Late Bronze Ages, there was only a slight shift in dental health.

Large variation in nitrogen isotopic composition of a fertilized legume

Plant nitrogen isotopic compositions are highly variable and are influenced by a diversity of environmental and anthropogenic factors, including the application of animal-derived fertilizers. Legumes that acquire most of their nitrogen from atmospheric N2 (rather than mineralized soil nitrogen) tend to have relatively low δ15N values (consistently around 0‰), and it has been presumed that their δ15N values are largely or wholly unaffected by fertilization. This study presents nitrogen isotopic data from leguminous (garden bean, Phaseolus vulgaris) and non-leguminous (summer squash, Cucurbita pepo) plants subjected to seabird guano fertilization while growing under controlled conditions. Both bean and squash tissue δ15N values were substantially increased by seabird guano fertilization: +16.3 to +19.2‰ for bean and +19.6 to +24.5‰ for squash. The results of this study demonstrate that the enrichment in plant 15N resulting from seabird guano fertilization occurs consistently in non-maize species. Moreover, it demonstrates that under conditions of high soil nitrogen availability, leguminous plants may obtain a substantial portion of their nitrogen through the uptake of inorganic soil nitrogen (ammonium and nitrate), rather than atmospheric N2. In general, where the δ15N values of fertilizers differ substantially from that of endogenous soil nitrogen and mineralized nitrogen derived from the fertilizer is readily available, a significant manuring effect can be expected in leguminous plants.

Stable nitrogen isotope analysis of dentine serial sections elucidate sex differences in weaning patterns of wild chimpanzees (Pan troglodytes)

Offspring provisioning is one of the most energetically demanding aspects of reproduction for female mammals. Variation in lactation length and weaning strategies between chimpanzees (Pan troglodytes), our closest living relative, and modern human societies have been reported. When and why these changes occurred is frequently debated. Our study used stable nitrogen isotope data of tooth root dentine from wild Western chimpanzees (Pan troglodytes verus) in Taï National Park, Côte d'Ivoire, to quantify weaning in these chimpanzees and explore if infant sex plays a role in maternal investment. We analyzed serial sections of deciduous lateral incisor root dentine from four Taï chimpanzees to establish the δ(15) N signal of nursing infants; we then analyzed serial sections of first permanent mandibular molar root dentine from 12 Taï chimpanzees to provide quantitative δ(15) N data on weaning in this population. Up to 2 years of age both sexes exhibited dentine δ(15) N values ≈2-3‰ higher than adult female Taï chimpanzees, consistent with a nursing signal. Thereafter a steady decrease in δ(15) N values consistent with the onset, and progression, of weaning, was visible. Sex differences were also evident, where male δ(15) N values decreased at a significantly slower rate compared to females. Confirmation of sex differences in maternal investment among Taï chimpanzees, demonstrates the viability of using isotope analysis to investigate weaning in non-human primates. Additionally, assuming that behaviors observed in the Taï chimpanzees are illustrative of the ancestral pattern, our results provide a platform to enable the trajectory of weaning in human evolution to be further explored.

Factors influencing stable nitrogen isotope ratios in wing membranes of insectivorous bat species: A field study

Nitrogen stable isotope analysis studies have become a useful tool in dietary studies to quantify differences in diet composition among species or individuals. However, laboratory studies have revealed several factors that influence the nitrogen isotope ratios (δ15N) in animal tissues (e.g. habitat, amount of ingested food, and metabolic rate). The influence of these factors has not been validated for free-ranging bat species, which is important for interpreting nitrogen isotope data in field studies. In this study, we measured δ15N from wing membranes (δ15Nw) and habitat samples (δ15Nh; soil and leaf, or sediment) to test for effects of diet, age, and individual energy demand in three free-living bat species (Myotis daubentonii, Nyctalus noctula and Nyctalus leisleri). We hypothesised that based on differences in diet composition δ15Nw values should increase in the sequence M. daubentonii, N. leisleri, and highest N. noctula. Furthermore, juveniles should have significantly lower δ15Nw compared to their mothers. Thirdly, the δ15Nw values of reproductively active individuals should be significantly higher than those of non-reproductive individuals. Values of δ15Nw were significantly influenced by differences in feeding ecology among species and individual reproductive status, but not by animal age. Our results show that species feeding on primary consumers have lower δ15Nw values than species feeding on secondary and tertiary consumers. Further, independent young did not differ in their δ15Nw values from adults suggesting that their tissues already reflect the insect diet. The effect of reproductive status varied among species which might reflect intra-specific differences in foraging behaviour of generalist vs. specialist species. In this study, we demonstrated that δ15N can provide information on the dietary range of bats, but researchers should account for variation owing to reproductive status, habitat, and species.

Environmental changes in the Late Ordovician-early Silurian: Review and new insights from black shales and nitrogen isotopes

The Late Ordovician (Katian-Hirnantian) through earliest Silurian (Rhuddanian) interval was a time of varying climate and sea level, marked by a peak glacial episode in the early-mid-Hirnantian. Synthesis of recently published data permits global correlation of at least two cycles of glacial advance and retreat with a distinct interglacial period that is recognizable in sequence-stratigraphic and chemostratigraphic records in many parts of the world. A period of warming and sea-level rise during the late Katian is marked by the widespread occurrences of oceanic anoxia in paleotropical and subtropical localities, mostly confined to regions of inferred upwelling and semirestricted marine basins. Nitrogen isotope data show that the regions of oceanic anoxia were marked by intense water-column denitrification in which cyanobacteria were the principal source of fixed N. In the overlying peak glacial interval of the Hirnantian, sedimentary successions from localities representing a wide range of water depths and paleolatitudes indicate that anoxia was restricted during the early-mid-Hirnantian. The shift to more positive N isotope values also suggests less intense water-column denitrification. In the overlying late Hirnantian and early Rhuddanian, the distribution of black shales reaches its greatest extent in the studied interval. Localities showing evidence of anoxia are globally spread over all paleolatitudes and water depths for which data are available, indicating a Rhuddanian ocean anoxic event comparable to examples from the Mesozoic. It is accompanied by a return to intensely denitrifying conditions within the water column, as indicated by the shift to negative N isotope values. The two phases of Hirnantian mass extinction coincide with rapid, climate-driven changes in oceanic anoxia. The first extinction occurred at the onset of glaciation and with the loss of anoxic conditions at the end of the Katian. The second extinction occurred at the demise of glaciation and coincided with the return of anoxic conditions during the late Hirnantian–early Rhuddanian. Integration of our N isotope data with graptolite biodiversity records suggests that the extinctions were profoundly influenced by changes occurring at the base of the marine food web, i.e., redox-driven changes in nutrient cycling and primary producer communities.

Tracing the mobility of individuals using stable isotope signatures in biological tissues: “locals” and “non-locals” in an ancient case of violent death from Central California

Stable isotope analyses of biological tissues that grow during different phases of life can be used to trace the geographic location of individuals during different windows of time. We apply this principle and reexamine three prehistoric skeletons excavated in 1964 from archaeological site CA-YOL-117 in Central California. Field evidence suggests they were killed as part of a single violent event. We report new radiocarbon dates and Strontium, Oxygen, Carbon, and Nitrogen isotopic data from first molars, third molars, and bone to examine circumstances surrounding their death. Data suggest two of the three individuals were born, and all three lived their teenage years, near the site they were buried in. However, as adults they lived elsewhere, likely to the north along the Sacramento River. Around AD 1450, upon returning to the territory of their childhood years, they were killed and placed in a mass grave. The data invite a more nuanced interpretation of how we view “local” and “non-local” individuals archaeologically. Overall, the analysis provides an interesting glimpse into the nature of warfare and violence among pre-contact hunter–gatherers of Northern California.

Stable carbon and nitrogen isotopes as indicators of sedentism and territoriality in late Holocene South Australia

AbstractPrevious research has presented hypotheses concerning the presence of widespread Aboriginal sedentism in coastal and riverine South Australia during the past 5000 years. These hypotheses were based on biological distance data (metric and non‐metric), isotopic analyses at the inland Roonka Flat site and the emergence of large, well‐defined cemeteries throughout the region. Stable carbon and nitrogen isotope data for a large burial population at the Swanport archaeological site in the lower Murray River Basin of South Australia, near the coastal river mouth, provide additional evidence for the presence of hunter–gatherer sedentism and territoriality during the late Holocene. Stable isotope research provides a powerful method to examine subsistence‐settlement systems and social relations in prehistoric populations.

The Late Pleistocene Belotinac section (southern Serbia) at the southern limit of the European loess belt: Environmental and climate reconstruction using grain size and stable C and N isotopes

The Belotinac loess section is one of the southernmost loess-paleosol environmental archives for the Late Quaternary in Serbia. The climate at this site is intermediate between the continental and the Mediterranean realms, which makes this loess archive potentially highly sensitive to past climatic changes. This paper presents new insights into the paleoenvironmental history during the last glacial period in southern Serbia using grain size and isotope proxy data. The grain size parameters from the Belotinac section reveal variations in the paleowind dynamics and weathering intensity, and suggest the nearby valley of the Južna Morava River as an important source of aeolian sediments in this area. Based on a multiproxy dataset, alternating phases of weak interstadials and phases of enhanced loess deposition at this site were identified. Nitrogen isotope data suggest that during Marine Isotope Stage 3, ecosystems of high biomass productivity and rather open N-cycles prevailed. During Marine Isotope Stage 2, productivity was reduced and the N cycle was more strongly closed, probably due to a shorter growing season and more pronounced temperature decline. Carbon isotope data indicate a possible contribution of C4 plants to the Holocene vegetation, but not to the glacial and interstadial ecosystems of the Late Pleistocene. Changes in atmospheric CO2 level are not reflected in the carbon isotope record. These findings are discussed in the light of paleoclimate proxy datasets from the Morava River valley and Carpathian Basin, as well as through comparison of carbon isotope records from loess sections in SE – Central Europe and in the Rhine Valley. Two different loess provinces exist in terms of glacial-interglacial humidity changes: a province of “glacial drying” and a province of “glacial humidification”. The first includes loess sites under more oceanic influence, where loess δ13C records indicate humid interglacials and interstadials and relatively drier glacial periods. The second includes the loess sites of the Carpathian Basin and especially the southern Serbian loess area of Belotinac, where loess δ13C records indicate more intensive aridity during interglacials, but a reduced soil moisture deficit and a more humid climate due to lower evapotranspiration in interstadials, and even more in glacial periods.

Interpreting Oral Pathology at Machu Picchu, Peru

AbstractThis study analyzes oral pathological conditions—caries, antemortem tooth loss, and occlusal macrowear—among adults (N = 70) interred at Machu Picchu, Peru. Previous isotopic diet reconstructions at Machu Picchu suggest substantial early‐life variation that may have narrowed somewhat by the last decade of life. This study seeks to further elucidate the intersection of diet, sex, and health at Machu Picchu by analyzing oral pathological conditions with existing carbon and nitrogen isotopic data. Observed caries prevalence is corrected to control for age and tooth loss, and is described for both anterior and posterior teeth; wear data are scored and reported for individual tooth types. Results indicate caries prevalence consistent with carbohydrate‐rich diets and no significant difference between males and females. However, no significant isotopic parameters are associated with caries prevalence in young adult males, while caries prevalence is significantly associated only with enamel carbonate δ13C in older adult males. Dietary protein sources, but not C4 resources, are associated with caries prevalence in young adult females, and to a lesser degree in older adult females. Significant associations between occlusal wear and caries exist among young adult males and young adult females, but involving different tooth types. These findings suggest differential protein consumption at Machu Picchu between males and females, and separate masticatory and physiological processes shaping caries prevalence between the sexes at the site. This study therefore underscores the role that gender roles may have played in diet variation among this population and the need to account for sex in analyzing oral pathology. Copyright © 2013 John Wiley & Sons, Ltd.