Excavations at Knossos have uncovered faunal and archaeobotanical archives spanning the Neolithic and Bronze Age (7th–2nd millennia bce), during which one of Europe’s earliest known farming settlements developed into its first major urban settlement and centre of one of its oldest regional states. Through stable isotope (δ13C, δ15N) analysis of seeds and bones (as evidence for the growing conditions of cereal and pulse crops and for the types of forage consumed by livestock), land use and, ultimately, political economy are explored. Changing husbandry conditions overwrite any effects of long-term aridification. Early (7th–6th millennium bce) Knossian farmers grew intensively managed cereals and pulses (probably in rotation) that were closely integrated (as manured sources of forage) with livestock. Through the later Neolithic and Bronze Age, settlement growth accompanied more extensive cultivation (eventually with cereals and pulses not in rotation) and greater use of rough graze and, by goats, browse. Pasture on cultivated land remained central, however, to the maintenance of sheep, cattle, and pigs. Variable diet of early sheep suggests management at the household level, while thereafter progressive dietary divergence of sheep and goats implies their separate herding. Until the Old Palace phase (early 2nd millennium bce), urban growth was matched by increasingly extensive and probably distant cultivation and herding but somewhat more intensive conditions during the New and Final Palace phases (mid-2nd millennium bce) perhaps reflect greater reliance on surplus from prime land of previously rival centres that now came under Knossian control.

This article discusses the composition of prehispanic diets based on the isotopic composition (δ13C, δ15N) of 10 human samples dated between 3600 and 1300 BP from the Cajón Valley in Northwest Argentina. The sample is the only one available for the time and region considered and covers a 2,300-year range. It shows long-term tendencies in the consumption of food resources during a time when people were experimenting with and eventually domesticating plants and animals in the high-altitude Southern Calchaquíes valleys. Results indicate that animals contributed more to the diet than was expected and plants correspondingly less than expected. This proportion was maintained even during the human occupations associated with the agropastoral villages of Cardonal and Bordo Marcial (ca. 2000 BP) when a greater contribution of plant resources—in particular maize—would be expected. This new evidence demonstrates the diversity of productive strategies used by the societies of Northwest Argentina at the beginning of the Formative period. A variety of resources contributed to daily food intake, minimizing the importance of maize in the diet.

With the popularization of carbon and nitrogen stable-isotope analysis methods used on archaeological samples from Xinjiang, the ancient paleodiet there has been revealed. However, research about isotopic analysis combined with environmental factors is rare, especially in such a variable and complex climate as that of the Tianshan region. We systematically analyzed the δ13C and δ15N results from animals and humans for dietary reconstruction of nomadic pastoralists from the Tianshan region during 3900–1200 cal BP. The δ13C and δ15N values for animals (sheep/goat, horse and cattle; n = 57) have a wide range from –20.8‰ to –14.7‰ for δ13C (–19.2 ± 1.0‰) and 3.2‰ to 9.9‰ for δ15N (7.0 ± 1.2‰). The δ13C and δ15N values from humans range from –19.6 to –12.3‰ (–16.0 ± 1.5‰) and 7.1 to 16.7‰ (–13.6 ± 1.5‰), respectively. The animal δ15N results indicate that the dry environment in the Tianshan region may result in elevated δ15N values. Synthesizing animal and human isotope results suggests that the inhabitants engaged in mobile herding economies subsidized with crops and wild animal meat from the Tianshan Mountains. In conclusion, we found that the regional environment closely relates to crop types, and temporal climate change has an effect on human dietary structure. Therefore, climate condition cannot be ignored when studying human paleodiet.

Differences in the diets of urban and rural avian predators could indicate potential niche vulnerability in a particular habitat. This study compares the core-isotopic niche areas and diet disparity of a declining peri-urban Verreaux’s Eagle Aquila verreauxii population with a stable rural population in South Africa. In addition to stable isotope analyses, the diet of the peri-urban Verreaux’s Eagles was investigated using camera trap footage of prey delivered during the nesting season. Dominant prey consisted of species with a mixed diet of plants with a C3 and/or C4 photosynthetic pathway (browsers and grazers). Rock hyrax Procavia capensis contributed 60% of the total diet composition, scrub hare Lepus saxatilis 26% and Helmeted Guineafowl Numida meleagris 22%. The core-isotopic niche area for each population was calculated using bulk carbon (δ13C) and nitrogen (δ15N) stable isotope values chronological measured along the length of 18 feathers from 21 nests. The isotopic niche of the rural eagle population revealed that they consume prey from multiple trophic levels with a C3-plant-dominated prey base (browsers), likely including small carnivores. In contrast the isotopic niche of the peri-urban Verreaux’s Eagles correlated with the mixed mammalian and avian food-niche determined from camera trapping, confirming that the peri-urban population mainly hunted three abundant species that are all narrowly associated with modified human habitats. The decline in the Magaliesberg Verreaux’s Eagle population is, therefore, unlikely to be due to constraints in their dietary niche, as raptors benefit from the diversity and abundance of human-commensal prey associated with the peri-urban habitats.

A new fossil site in a previously unexplored part of western Madagascar (the Beanka Protected Area) has yielded remains of many recently extinct vertebrates, including giant lemurs (Babakotia radofilai, Palaeopropithecus kelyus, Pachylemur sp., and Archaeolemur edwardsi), carnivores (Cryptoprocta spelea), the aardvark-like Plesiorycteropus sp., and giant ground cuckoos (Coua). Many of these represent considerable range extensions. Extant species that were extirpated from the region (e.g., Prolemur simus) are also present. Calibrated radiocarbon ages for 10 bones from extinct primates span the last three millennia. The largely undisturbed taphonomy of bone deposits supports the interpretation that many specimens fell in from a rock ledge above the entrance. Some primates and other mammals may have been prey items of avian predators, but human predation is also evident. Strontium isotope ratios (87Sr/86Sr) suggest that fossils were local to the area. Pottery sherds and bones of extinct and extant vertebrates with cut and chop marks indicate human activity in previous centuries. Scarcity of charcoal and human artifacts suggests only occasional visitation to the site by humans. The fossil assemblage from this site is unusual in that, while it contains many sloth lemurs, it lacks ratites, hippopotami, and crocodiles typical of nearly all other Holocene subfossil sites on Madagascar.

Various herbivorous invertebrates in seagrass beds are considered to be generalists in food use and their diets may temporally fluctuate according to the availability of food sources. We assessed whether food sources of herbivorous gastropods vary in a subtropical seagrass bed in Nagura Bay, Ishigaki Island, where coexisting seaweeds grow densely in spring but minimally in summer. Abundant gastropods and their possible food sources were collected in spring and summer of 2013 and 2015, and their stable carbon and nitrogen isotope ratios were measured. Between the two seasons, each possible food source had similar isotopic values, but all the herbivorous gastropod species in summer were more enriched in 13C than the gastropod samples in spring. The mixing models in SIAR (Stable Isotope Analysis in R) showed that the total contribution rates of seaweeds, i.e. rhodophytes, phaeophytes and chlorophytes, for all herbivorous gastropod species decreased from spring to summer; in contrast, the contribution rate of seagrasses increased. Linear Mixed Models showed that the seasonal variation in δ13C of the herbivorous gastropods was larger than that of the possible food sources, adding further evidence to the seasonal change in food sources of the herbivorous gastropods. This seasonal change in food use appears to correspond to the change in seaweed biomass, suggesting that herbivorous gastropods flexibly change their diets depending on food availability.

We identified human paleodietary changes from inhabitants of the Guanzhong basin since 8000 BP, based on published carbon and nitrogen isotopic measurements on bones, fauna and plant remains. We also directly measured 14C ages, δ13C and δ15N values from bones unearthed at the Zhouyuan site, west of Guanzhong, in order to reconstruct paleodietary changes of the ancient inhabitants. We found that during the Laoguantai period, animal foods were the main source of nourishment with supplementary plant-derived foods. After this period, plant-derived foods became the main food source, with supplementary animal sources. The development of dry farming led to increased consumption of foxtail millet and broomcorn millet. This trend persisted and marked a fundamental shift from hunting, gathering, and fishing to farming and animal domestication. The dietary trends of the ancient inhabitants also show pronounced regional differences through time. The use of domestic animals was proportionally higher in the eastern part of the Guanzhong region, while wild animals were more common in the west.

This study uses two novel archaeobotanical techniques – crop carbon and nitrogen isotope analysis and functional weed ecology – to determine directly how the intensity of agricultural practice changed from the Neolithic to the Early Iron Age in south-west Germany, with the emergence of fortified hilltop settlements (Fürstensitze or chiefly seats) regarded as the first urban centres in central Europe. The crop isotope and functional weed ecological evidence suggest that surplus cereal production in the Early Iron Age was achieved through sustained use of manure combined with expansion in arable cultivation, both developments that are connected with more widespread use of animal traction. The increased scale of cultivation is broadly apparent across rural as well as fortified hilltop centres in the Early Iron Age, and considerable variability in manuring intensity is consistent with agricultural decision-making at a local level rather than centralised control. Additionally, the more intensive manuring of hulled six-row barley, used in beer production, demonstrates that the political importance of drinking and feasting in Early Iron Age society was reflected in crop husbandry practices. In terms of animal husbandry, faunal isotope data reveal a radical decrease in forest cover, potentially reflecting an expansion in the scale of herding accompanying that of arable cultivation. Site-specific patterning points to a range of herding strategies, from specialised herding of cattle at the Heuneburg to generalised patterns of livestock management at rural sites.

Disentangling trophic interactions among species is important for elucidating mechanisms underlying ecosystem functioning and services. Carabid beetles are an important guild of predators that may regulate pest populations in arable landscapes, but their generalist feeding behavior hinders predictions about their actual contribution to pest control. In order to assess carabids’ potential for pest control, we simultaneously analyzed the carbon and nitrogen stable isotope ratios of a community of 45 co-occurring species in wheat and oilseed rape fields. With the expectation to identify distinct trophic groups based on the mean and the variance of carabid isotopic signatures, we observed a high degree of overlap in trophic positions between species. However, we also observed that species could be successfully categorized into two groups according to whether or not their carbon signatures varied independently from variations in the crop baseline. We interpret these results as differential primary resource uptake or by differential mobility aptitude in foraging. Accordingly, we propose that the isotopic signal can inform us on the presence/absence of links between generalist predators and cultivated plants through the trophic networks they belong to, and consequently on their potential role as pest natural enemies. We therefore suggest the complementarity of stable isotope analysis for obtaining a time-integrated assessment of carabid trophic behavior that may be combined with more direct molecular diet analysis allowing the simultaneous quantification of specific trophic links within agricultural landscapes.

In order to obtain a better knowledge of past oceanographic variability offshore southern Chile, this study reappraises the changes in the sources of nutrients over the last 25 ka based on a detailed comparison of previously published nitrogen isotope and microfossil records (dinoflagellate cysts, coccoliths and diatoms) from ODP Site 1233 (41°S). Our findings support the main conclusions of Martinez et al. (2006) in the sense that both the Subantarctic Surface Water and the Gunther Undercurrent are potential sources for the recorded late Quaternary sedimentary δ15N signatures at Site 1233, with variable contributions of both sources during different time periods. This study indicates that Subantarctic Surface Water forms the main source for nutrients during the last glacial maximum (25–18.6 cal ka BP), the first part of the deglaciation (18.6–15.7 cal ka BP) and the Holocene (9.8 cal ka BP until present). An increased contribution of Equatorial Subsurface Water as a source of nutrients to the photic zone offshore southern Chile is observed between 14.4 and 9.8 cal ka BP, which is indicative for upwelling conditions at least after 13.2 cal ka BP as indicated by the microfossil data.

Previous research on the small mammal population recovered from archeological excavations at the Wasden Site in southeastern Idaho suggests that changing frequency distributions through time represent a shift in climate during the early Holocene from a cooler, wetter regime to a warmer, drier one. This conclusion was re-evaluated using stable carbon and nitrogen isotope analyses of bone collagen from the three species of small mammals examined in the earlier studies: pocket gophers (Thomomys talpoides), pygmy rabbits (Brachylagus idahoensis), and ground squirrels (Spermophilus townsendii). Resulting carbon and nitrogen isotopic values are consistent with known differences in feeding ecology, suggesting high fidelity as proxies for past vegetation (and thus climate) regimes. Patterns of 15N enrichment and increased representation of C4-CAM vegetation observed in the pocket gophers, and to a lesser extent ground squirrels, suggests increasing warmth and/or aridity from the early Holocene until ∼7000 cal yr BP, thus supporting previous hypotheses of climate change on the eastern Snake River Plain. The results highlight the potential contribution of such studies for archeological research by providing additional proxies for environmental conditions that bear on paleoecological adaptations to climatic change, including past human use and occupation of the region.

Presented here are stable nitrogen isotope data from a rock hyrax (Procavia capensis) middens from northwestern Namibia that record a series of rapid aridification events beginning at ca. 3800 cal yr BP, and which mark a progressive decrease in regional humidity across the Holocene. Strong correlations exist between this record and other terrestrial and marine archives from southern Africa, indicating that the observed pattern of climate change is regionally coherent. Combined, these data indicate hemispheric synchrony in tropical African climate change during the Holocene, with similar trends characterising the termination of the ‘African Humid Period’ (AHP) in both the northern and southern tropics. These findings run counter to the widely accepted model of direct low-latitude insolation forcing, which requires an anti-phase relationship to exist between the hemispheres. The combined dataset highlights: 1) the importance of forcing mechanisms influencing the high northern latitudes in effecting low-latitude climate change in Africa, and 2) the potential importance of solar forcing and variations in the Earth's geomagnetic shield in determining both long-term and rapid centennial-scale climate changes, identifying a possible mechanism for the variations marking the AHP termination in both the southern and northern tropics.

Rapid and massive amphibian population declines have been reported throughout upland areas of the Neotropics. The abundance and species richness of Neotropical amphibian communities suggest that losses of this magnitude are likely to have strong effects at the ecosystem level. To improve understanding of the implications of their loss we used stable isotope analysis to examine trophic relationships in an ecosystem in which amphibians are dominant in a second-order forest stream at 750 m asl in Parque Nacional Omar Torrijos Herrera, Panama. We analysed δ13C, δ15N and C:N ratios of major biotic components (basal resources, invertebrates, amphibians, fish and reptiles) in the stream and of the adjacent riparian food web. Tadpoles (mean δ15N = 4.49‰) and adult amphibians (mean δ15N = 5.45‰) were intermediate links in the aquatic and terrestrial food web respectively. High δ15N signatures identified fish as top predators in the aquatic food web and snakes and the toad Bufo as top predators in the terrestrial food web. Isotopic signatures clearly distinguished between trophic groups of tadpoles: microbial feeders (Centrolenidae, δ15N range = 0.91–3.05‰), herbivores (Rana and Hyla, δ15N range = 4.74–5.15‰) and neuston feeders (Colostethus, δ15N range = 5.31–6.40‰). Dependence on autotrophic production was indicated by enriched signatures of carbon isotopes in pool dwellers versus those that reside in faster-flowing sections of the stream. High nitrogen concentrations in detrital matter (average 0.8%, C:N = 10.3) suggested that grazing tadpoles enhanced nitrogen fluxes and improved the quality of organic matter available to detritivores.

Trophic relationships among animals, plants and microflora are the basis for the construction of terrestrial and aquatic food webs, but both the structure and dynamics of food webs remain contentious. Examples of issues include how the overall nutrient status of a system affects the number of trophic levels, whether trophic-level omnivory and intraguild predation are rare or important, if different animal species can be aggregated into functional groups according to their taxonomic affiliation, how large numbers of decomposer animal species can coexist and why there are so many parthenogenetic taxa in soil.

This paper is a first study of duration of breastfeeding using bone stable isotopes in infants in a British palaeopopulation, from the deserted Mediaeval village of Wharram Percy, England. Nitrogen stable isotope analysis suggests cessation of breastfeeding between 1 and 2 years of age. Comparison with Mediaeval documentary sources suggests that recommendations of physicians regarding infant feeding may have influenced common practice in this period.

An experiment was performed to find out whether ectomycorrhizal (ECM) fungi alter the nitrogen (N) isotope composition, δ15N, of N during the transport of N from the soil through the fungus into the plant. Non- mycorrhizal seedlings of Pinus sylvestris were compared with seedlings inoculated with either of three ECM fungi, Paxillus involutus, Suillus bovinus and S. variegatus. Plants were raised in sand in pots supplied with a nutrient solution with N given as either NH4+ or NO3−. Fractionation against 15N was observed with both N sources; it decreased with increasing plant N uptake, and was larger when NH4+ was the source. At high ratios of Nuptake/Nsupplied there was no (NO3−), or little (NH4+), fractionation. There seemed to be no difference in fractionation between ECM and non-mycorrhizal plants, but fungal rhizomorphs were sometimes enriched in 15N (up to 5‰ at most) relative to plant material; they were also enriched relative to the N source. However, this enrichment of the fungal material was calculated to cause only a marginal decrease (−0.1‰ in P. involutus) in δ15N of the N passing from the substrate through the fungus to the host, which is explained by the small size of the fungal N pool relative to the total N of the plant, i.e. the high efficiency of transfer. We conclude that the relatively high 15N abundance observed in ECM fungal species should be a function of fungal physiology in the ECM symbiosis, rather than a reflection of the isotopic signature of the N source(s) used. This experiment also shows that the δ15N of plant N is a good approximation of δ15N of the available N source(s), provided that N is limiting growth.

Natural abundances of 15N and N concentrations of 34 fruit bodies from 24 species of ectomycorrhizal and saprophytic fungi were measured in a temperate Central European mixed forest stand. The fungi of the two life forms are known to be capable of utilizing different types of N sources (organic N compounds from the humus, inorganic N from the soil and N from litter or wood) differing by their 15N natural abundance values. Based on the two life forms and the three different N sources, four functional groups of fungi were distinguished: (1) ectomycorrhizal fungi capable of utilizing organic N from the humus; (2) ectomycorrhizal fungi known to depend on inorganic N compounds in the soil; (3) saprophytes capable of utilizing organic N from the humus; and (4) saprophytes utilizing N from dead wood or litter. Large differences were found between species in the δ15N values (−3.0 to 3.3‰) and in the N concentrations (0.84 to 6.61 mmol eq N g dw−1) of the fruit bodies. In most cases fungi were more enriched in 15N than their respective bulk N source was. Fungi living in humus, and presumably having access to organic N compounds (groups 1 and 3), were significantly more enriched in 15N than fungi which are known to depend on inorganic N (e.g. Laccaria, group 2), or fungi living on litter or wood (group 4), irrespective of whether they were ectomycorrhizal or saprophytic species. Fungi living in humus had significantly higher N concentrations than fungi living on litter or wood.

The natural 15N abundance method for estimating symbiotic biological N2-fixation was tested on legume trees from two rain forests on contrasting soils (oxisols and spodosols) in French Guiana. When possible, the significance of N2-fixing species in the plant community was evaluated in terms of density, biomass and contribution of N2-fixation to the building up of the total nitrogen mass in the leaves. Of the two sites, the rain forest on spodosols was the less favourable for application of the δ15N method: the available soil nitrogen was isotopically similar to fixed-N2. Hence, the results showed that a reliable estimate of N2-fixation could not be obtained. A substantial contribution of fixed-N2 to the nitrogen nutrition of legumes was found on oxisols, with an average value of 54 % Ndfa (Nitrogen derived from the atmosphere). The contribution of the N2-fixing legumes to the biomass of the stand was estimated to be 2 t ha−1 for the leaf biomass and 136 t ha−1 for the total above-ground plant biomass. With 7.5 % of trees in the stand able to fix N2 (462 out of 6156), N2-fixation was estimated to be 7 kg ha−1 y−1. These results are the first use of the δ15N method to estimate nitrogen input by N2-fixing legumes to a natural rain forest. The inter-site variability observed in the δ15N of the non-fixing plants suggested different nitrogen-cycling processes in the two soils. The δ15N of the non-N2-fixing plants could be related to the soil nitrogen availability and be used as an indicator of efficient or non-efficient nitrogen-cycling rain forests. The spatial variability of the δ15N in the plant-available soil nitrogen pool and the nitrogen balance in tropical rain forests are discussed.

The 15N natural abundance and N concentrations of fruit bodies from 70 species (23 genera) of ectomycorrhizal fungi found in boreal forests are presented. Large intraspecific and intrageneric differences were found, e.g. 8·3‰ 15N in the species Dermocybe crocea and 12·6‰ in the genus Cortinarius. In addition, significant differences in both δ15N and %N were found between different parts of fruit bodies, with cap material giving consistently higher values. Proteins and amino acids were enriched by 9·7±0·4‰ (mean±1 SE) relative to chitin, irrespective of the part of the fruit body examined. Chitin had δ15N values similar to that of plant hosts. The higher δ15N and %N values of the caps than of the stipes probably reflect a higher portion of proteins and amino acids in the caps. The δ15N of mycorrhizal fungi can be a function of the N species used (organic N, NH4+, NO3−), the depth of soil at which the mycelium occurs, and metabolic fractionations. The metabolic fractionations, e.g. potential transaminations during the flux of N from the soil through the fungus to the plant, make it difficult, at present, to make inferences about sources of N based on δ15N values alone. No effect of sample drying temperature on δ15N values of fungal material was detected.