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High-altitude conditions on the Tibetan Plateau are often depicted as an inhospitable environment for conventional farming, yet evidence shows that communities in western Tibet grew ecologically hardy crops such as 6-row barley (Hordeum vulgare) by at least the 1st millennium BCE, at locations above 4,000 meters above sea level (masl). However, little is known about the specific cultivation strategies and culinary traditions that these agropastoral communities developed. Stable carbon and nitrogen isotope compositions of grains inform growing conditions and provide much needed insight into the cultivation strategies in such a unique environment. We use δ13C and δ15N values of archaeologically recovered barley remains to investigate past watering and soil-management strategies. Our results infer high labor investment in manuring and watering in barley farming. This suggests an intensive cultivation system in Western Tibet, 1,000 BCE −1,000 CE, despite the high-altitude pastoral landscape.

Stable isotope analysis of plant remains recovered from archaeological sites is becoming more routine. There remains a lack of consensus, however, on how to appropriately select archaeological plant remains for isotopic analysis, how to account for differences in preservation and the effect of potential contamination, and how to interpret the measured isotope values in terms of the conditions in which the plants grew. In this paper, we outline the main issues to be considered when planning and conducting an isotopic study of archaeobotanical remains. These include: (1) setting out the research question(s) that will be answerable using available analytical approaches, (2) considering the archaeological context from which plant remains derive, (3) determining appropriate sample size through consideration of estimate precision, (4) establishing the conditions in which plant remains have been preserved and potential effects on their isotope values, and (5) accounting for possible contamination during deposition. With these issues in mind, we propose some recommendations for researchers to consider when planning and conducting an isotopic study of archaeobotanical remains.

Studies of climate variation commonly rely on chemical and isotopic changes recorded in sequentially produced growth layers, such as in corals, shells, and tree rings, as well as in accretionary deposits—ice and sediment cores, and speleothems. Oxygen isotopic compositions (δ18O) of tooth enamel are a direct method of reconstructing environmental variation experienced by an individual animal. Here, we utilize long-forming orangutan dentitions (Pongo spp.) to probe recent and ancient rainfall trends on a weekly basis over ~3–11 years per individual. We first demonstrate the lack of any consistent isotopic enrichment effect during exclusive nursing, supporting the use of primate first molar teeth as environmental proxies. Comparisons of δ18O values (n=2016) in twelve molars from six modern Bornean and Sumatran orangutans reveal a high degree of overlap, with more consistent annual and bimodal rainfall patterns in the Sumatran individuals. Comparisons with fossil orangutan δ18O values (n=955 measurements from six molars) reveal similarities between modern and late Pleistocene fossil Sumatran individuals, but differences between modern and late Pleistocene/early Holocene Bornean orangutans. These suggest drier and more open environments with reduced monsoon intensity during this earlier period in northern Borneo, consistent with other Niah Caves studies and long-term speleothem δ18O records in the broader region. This approach can be extended to test hypotheses about the paleoenvironments that early humans encountered in southeast Asia.

New stable carbon (δ13C) and nitrogen (δ15N) isotope values of charred plant and bone collagen remains from 6th mill. BCE Halai, central Greece, together with datasets from 6th mill. BCE Kouphovouno, southern Greece, and later 6th/early 5th mill. BCE Makriyalos, northern Greece, demonstrate how early farming communities in mainland Greece adapted mixed farming strategies to distinct local environmental and cultural settings. Intra-site similarities and differences in δ13C and δ15N values of distinct crop species, along with the intra-species variabilities in stable isotopic values, are used to assess the cultivation choices that farmers at the three sites made to fulfil distinct economic goals. At Halai, farmers cultivated multiple crops under variable soil conditions, a strategy likely geared towards minimising overall risk in a relatively arid coastal setting. At better-watered Kouphovouno, by contrast, farmers practiced strategic manuring to maximise the yield of free-threshing wheat, likely grown exclusively for human consumption and rotated with nitrogen-fixing pulses. At Makriyalos, the limited sample size of cereal remains suggests a lack of intensive manuring, in contrast to the two other sites. Assessment of which crops may have been consumed by livestock sheds further light on symbiotic relationships between crop cultivation and animal husbandry. [ABSTRACT FROM AUTHOR]

Studies of climate variation commonly rely on chemical and isotopic changes recorded in sequentially produced growth layers, such as in corals, shells, and tree rings, as well as in accretionary deposits-ice and sediment cores, and speleothems. Oxygen isotopic compositions (δ 18 O) of tooth enamel are a direct method of reconstructing environmental variation experienced by an individual animal. Here, we utilize long-forming orangutan dentitions ( Pongo spp.) to probe recent and ancient rainfall trends on a weekly basis over ~3-11 years per individual. We first demonstrate the lack of any consistent isotopic enrichment effect during exclusive nursing, supporting the use of primate first molar teeth as environmental proxies. Comparisons of δ 18 O values (n=2016) in twelve molars from six modern Bornean and Sumatran orangutans reveal a high degree of overlap, with more consistent annual and bimodal rainfall patterns in the Sumatran individuals. Comparisons with fossil orangutan δ 18 O values (n=955 measurements from six molars) reveal similarities between modern and late Pleistocene fossil Sumatran individuals, but differences between modern and late Pleistocene/early Holocene Bornean orangutans. These suggest drier and more open environments with reduced monsoon intensity during this earlier period in northern Borneo, consistent with other Niah Caves studies and long-term speleothem δ 18 O records in the broader region. This approach can be extended to test hypotheses about the paleoenvironments that early humans encountered in southeast Asia., Competing Interests: TS, MA, CA, JN, MD, TL, PP, PV, Jd, IW, JZ, DG No competing interests declared, (© 2023, Smith et al.)