Department of Earth and Environmental Sciences at Nagoya University
By sequential sampling and analyzing tooth enamel, we can read the seasonal variations in stable isotope ratios recorded in teeth. Seasonal variations in the stable carbon (δ13C) and oxygen (δ18O) isotopes can be used to infer what the individual consumed, where, and in what season. In other words, this method is suitable for studying the husbandry strategies from livestock remains. However, in the analysis of an isolated tooth, the term of the obtained variation would be short, and difficult to capture the feature of the variation. Analyzing two teeth per individual can provide long-term variation, although this requires the use of well-preserved archaeological materials.
In our new study, we used this intra-individual sequential isotope analysis with M2 and M3 teeth per individual as far as possible to investigate early husbandry strategies in the southern Caucasus. We analyzed the mandibular tooth enamel of goats, sheep, and cattle (only isolated teeth) from the Neolithic settlements, Göytepe (ca. 5650–5460 cal BC) and Hacı Elamxanlı Tepe (ca. 5950–5800 cal BC) located in western Azerbaijan. As reference samples, we also analyzed modern goat and sheep individuals that are known to have grazed in the vicinity of the sites.
In this region, the first full-fledged Neolithic agro-pastoral economy called the Shomutepe-Shulaveri culture, emerged suddenly around 6000 cal BC. Despite their geographical closeness to each other, this is about 2000 to 3000 years later than the emergence of agro-pastoral practices in the Fertile Crescent. It is important to study the delay in this phenomenon in detail in order to understand the process of diffusion of agro-pastoral economy in human society. Therefore, in this study, we focused on how early agro-pastoral economy was practiced in this region under the peculiar environmental conditions colder in winter, adjacent to mountainous regions, that are uncommon in the Fertile Crescent. Livestock management regarding mobility and migration is a key aspect in understanding agro-pastoral societies. Therefore, we attempted to provide isotopic evidence indicative of early husbandry practices in the southern Caucasus.
The obtained data showed several different patterns that may be explained by different modes of husbandry practices:
Some of the goats and sheep exhibit large amplitudes in δ13C and δ18O variations (see figure above: part a). This was interpreted as a lowland pasturing pattern because the modern goat and sheep showed the same pattern.
A Neolithic goat and three Neolithic cattle samples exhibited relatively small amplitudes and/or inverse cyclical variation patterns (figure b and d). While these patterns may have been caused by multiple factors, such as drinking water and food/fodder, vertical transhumance has also been proposed to result in the similar isotope patterns (e.g., Henton et al., 2010; Tornero et al., 2016). If animals experience seasonal vertical transhumance between lowlands in winter and highlands in summer, it is expected that the δ13C fluctuation range reduces. In addition, the δ13C value of C4 plant feeders is presumed to decrease if they spend summer in highlands where C4 plants are less.
Some individuals illustrated a pattern with a larger amplitude of δ18O seasonal variations but a smaller amplitude of δ13C variations (c). It is likely that some factor reduced the variation of δ13C. We proposed a possibility of the use of fodder (C3 plants) collected in a short term and given to livestock thus dampening the seasonal variation in δ13C.
The factors contributing to the patterns of isotopic variation presented in our study may not be limited to transhumance or the use of fodder but are consistent with such possibilities. To verify these hypotheses, other analytical methods, such as strontium isotope analysis, are required to specify pasturing places in different seasons on the basis of a local and regional isoscape. In any case, at least, these various sequential isotopic patterns suggest that a variety of livestock breeding strategies were already adopted by Neolithic inhabitants in the southern Caucasus. Thus, long-term sequential isotope data from plural teeth per individual would provide us more specific seasonal variation patterns.
This research derives from the Azerbaijani-Japanese Archaeological Mission directed by Prof. Yoshihiro Nishiaki (The University of Tokyo) and Dr. Farhad Guliyev (The National Academy of Science, Azerbaijan). The financial support for this study was provided by the JSPS KAKENHI (No. 17H04534), the MEXT KAKENHI (No. 16H06408 and 20H00026), and The Takanashi Foundation for Historical Science.
Department of History, Shanghai Jiao Tong University, 200240 Shanghai, China
The Xinjiang region is located in far northwestern China neighboring central Asia and Mongolian Steppe. Throughout antiquity it has been a nexus for exchange in ideas, technologies, livestock, or even populations. Although most of its land is covered by severe environments such as the Taklamakan Desert, diverse cultures have been recognised since the early Bronze Age. Near Eastern cultivars such as wheat and barley have been excavated and dated to by the beginning of the second millennium BC in this region. In spite of the appearance of wheat and barley at some sites, did the subsistence of ancient Xinjiang populations really rely on these novel C3 cultivars? The degree to which these Near Eastern cultivars contributed to human dietary intake and how these new food types shaped local subsistence strategies remains poorly understood.
In this research, part of my Humboldt fellowship project hosted by Prof Cheryl Makarewicz at Kiel University, we conducted a regional scale meta-analyses of carbon and nitrogen isotope values measured from humans and animals including cattle, sheep/goats, and deer from sites dating from c. 2000 BC to AD 1000 within the Xinjiang region to examine the degree to which novel cultivars and animal proteins were incorporated into local subsistence system from the perspective of isotopic expression. We notice a narrow gap (1.7-2.7‰) in δ13C values but a wide space (4.5-6.5‰) in δ15N between humans and bovid samples. Meanwhile, we also record a consistent expression of high nitrogen isotope values visible in humans across time, indicating a persistent preference of the Xinjiang people for animal resources (e.g. meat, dairy proteins). This suggests novel cultivars of wheat and barley were not rapidly adopted in Xinjiang highlighting the food dispersal and acceptance across Eurasia during prehistory was a complex process.
Drawing on variations in bioavailable strontium in different environments to provenance biological materials has become increasingly common since its first application in archaeology almost four decades ago, and it is frequently applied to zooarchaeological materials. Provenancing biological materials, including faunal remains, using strontium isotope ratios generally requires a map of bioavailable strontium, commonly known as an isoscape, to compare results with. However, both producing the isoscape and using it to interpret results present methodological challenges that researchers must carefully consider.
To help researchers understand the complexities of strontium analysis, we reviewed current research to produce a critical synthesis and recommend best practices. We addressed sampling the archives needed to build an isoscape, applying the different mapping and modeling methods currently available, and interpreting the results of archaeological analyses against isoscapes. Our critical review is freely available to read and download from Earth-Science Reviews until May 8, 2021
Current research indicates that, while many archives can be analyzed to produce isoscapes, modern plant materials usually provide the best approximation of bioavailable strontium. Modern plants can be used alone or combined with other archives if applying a machine learning approach to mapping. In areas where erosion has significantly shifted the location of surface sediments, modern plants may not provide an appropriate archive for building an isoscape that is applicable to archaeological materials. In these areas, alternative archives such as archaeological rodent remains may be preferable. Archaeologists should also be aware that contemporary soil treatments like fertilizers may affect the bioavailable strontium in soils. Areas used for agriculture should be avoided when sampling.
It is essential to collect appropriate metadata when sampling. Collecting metadata improves the legacy benefits of strontium data by making them more broadly applicable. These metadata and the results of the analyses should be archived in one of several online databases to maximize their usefulness.
Mapping and modeling
We found that domain mapping currently produces the most accurate, most interpretable isoscapes for most research questions. However, machine learning approaches are also powerful and promise to provide more accurate and geographically wide-ranging isoscapes over time. Machine learning is computationally intensive and may not currently be an option for many researchers, but will be more widely available in the future.
Strontium isoscapes that are both appropriate and sufficiently high resolution to answer specific research questions do not exist for most parts of the world. Researchers intending to incorporate strontium analysis into their research designs should expect to conduct primary sampling and analysis to create appropriate isoscapes or refine existing ones, which should themselves not be utilized uncritically.
Strontium isotope analysis is currently the best developed and understood provenance tool. However, because isotope data can only exclude options of possible origin, the development of multi-isotope methods provides the route to a more powerful future approach. Using strontium isotope analysis for provenancing is most successful when combined with other isotopes and/or trace elements as part of a likelihood approach.
In the future, we expect that increasing amounts of primary data and the increasing application of machine learning approaches to mapping will mean that strontium analysis continues to improve as a method of provenancing.
The use of forests for pasturing and fodder resources remains globally an important, preventing over-grazing and providing complementary fodder in times of poor pasture. Traditionally, forests in Europe were a rich source of collected forage (leafy hay) in the form of branches and leaves. At the same time, herd animals can have a negative impact on forests, where grazing is unchecked. The first herders of Central and Northern Europe experienced a landscape ‘Bristling with forests and foul swamps’ as described by Tacitus in 98AD . The impact of animals on forests has been a focus of archaeologists for over 40 years. For example, Iversen  highlighted the importance of cattle in the expansion of the initial Neolithic settlements in his landam theory. The elm decline was initial contributed to increased use of leafy hay as animal forage.
How can we study forest pasture and foddering via stable carbon isotopes?
The canopy effect is where plants growing under dense forest canopies will exhibit depleted δ13C values. This is due to a combination of carbon -13 depletion of atmospheric CO2 under the canopy caused by CO2 respired by decaying organic matter and low light intensity at the forest floor decreasing photosynthesis efficiency. Consequently, animals browsing and grazing under heavy forest canopies or being fed leafy hay from these environments will exhibit low carbon isotope values in their tissues. Using this principal, researchers such as Dorothee Drucker and Rhiannon Stevens have explored the use of forests by wild ruminants past and present.
A cautionary note
The issue of equifinality can arise with the interpretation of stable isotopic values because different growing environments can produce similar effects on the stable isotopic ratios of plants. These continue up the food chain. For example, waterlogged environments can have a similar impact on δ13C values of plant communities as a dense forest canopy. Lynch and colleagues interpreted depleted δ13C values observed in British aurochs as a reflection of animals feeding on plants from waterlogged environments. Whereas, a similar study by Noe-Nygaard and colleagues of Scandinavian aurochs suggested these animals were forest dwellers. This is why it is key prior to the interpretation of stable isotopic results that robust interpretative frameworks using paleoenvironmental are created for testing hypotheses.
Independent methods for determining forest foddering
Compound-specific stable nitrogen isotope analysis of collagen amino acids provides an independent means for identifying consumption of woody plants, such as leafy hay. Developed by researchers at University of Bristol, direct evidence of the plant composition of animal fodder (woody/herbaceous) can be uncovered using the dietary β values based on δ15N CSIA of amino acids from incremental samples of dentine from cattle molars. These values represent the Δ15NGlx-Phe values of the plants at the base of the food web, using a known trophic offset of −4.0‰ between cattle and their diet. The dietary β values are then be compared with established ranges of Δ15NGlx-Phe values expected for herbaceous (−5.4±2.1‰) and woody plants (−9.3±1.6‰), based on modern references. Combining incremental analysis of enamel bioapatite and CSIA-AA of dentine of the same tooth provides a powerful method to identify forest pasturing and seasonal use of leafy-hay.
Look out for upcoming papers by myself and colleagues from University of Bristol, and European institutions from Hungary, Poland, France and Germany, discussing the role of forests in LBK cattle husbandry uncovered during the NeoMilk project (ERC-advance awarded to Prof. Richard Evershed).
1. Bogucki, P., 1988. Forest farmers and stockholders. Early agriculture and its consequences in North-Central Europe. Cambridge: Cambridge press.
2. Iversen, J., 1969. The influence of prehistoric man on vegetation, in The Neolithisation of Denmark: 150 years of debate., A. Fischer and K. Kristiansen, Editors. Sheffield Archaeological Monographs: Sheffield. p. 105-16.
Emily Lena Jones is an assistant professor of Anthropology at the University of New Mexico, Cyler Conrad is a Ph.D. graduate student in the Department of Anthropology at the University of New Mexico, and Seth Newsome is an assistant professor of Biology at the University of New Mexico. This post describes their collaborative research at the UNM Center for Stable Isotopes on prehistoric turkey husbandry in the American Southwest.
Maize Fed or Wild Diet?
Turkeys (Meleagris gallopavo) were used for a variety of economic purposes in the prehistoric American Southwest (Lang and Harris 1984). Turkeys were eaten; their feathers were used for blanket production; and their eggs were both consumed for food and used as binders in paint tempera formation. Ancient DNA evidence indicates prehistoric Southwesterners made use of both the wild Merrriam’s turkey (Meleagris gallopavomerriami) and a domestic turkey, which was genetically distinct from both Merriam’s and the Mexican domestic turkey (Speller et al. 2010).
Previous stable carbon (δ13C) and nitrogen (δ15N) isotope studies of Southwestern turkeys suggest that prehistorically, turkeys were predominately fed maize (Kellner et al. 2010; McCaffery et al. 2014; Rawlings and Driver 2010). Maize is a C4 plant, and the turkey bones so far sampled display a strong C4 signal (Figure 2).
Stable Isotope Research
Although previous studies have shown a remarkably consistent picture of turkey husbandry, the sample size from these studies is still relatively small.In addition, most of these studies have focused on sites in the Four Corners region or in Northern New Mexico. We are working to expand this sample to include turkeys from sites from the Middle Rio Grande Valley as well as more sites from high elevations or other “marginal” areas. We are analyzing both turkey bone collagen and apatite to understand the spacing and relationship between organic and inorganic isotope systems (Figure 3). Our data, from sites including Tijeras Pueblo (LA 581), Arroyo Hondo Pueblo (LA 12), and Chamisal Pueblo (LA 22765), suggests a more complex pattern of turkey husbandry practices than has been previously documented for the American Southwest. Within at least some contexts there appears to be a mix of maize-fed and wild-diet turkeys. We look forward to processing more samples and sharing our results in future publications and posts!
Kellner, Corina M., Margaret J. Schoeninger, Katherine Spielmann and Katherine Moore. 2010. Stable Isotope Data Show Temporal Stability in Diet at Pecos Pueblo and Diet Variation among Southwest Pueblos. In Morgan, Michèle E. (ed.) Pecos Pueblo Revisited: The Biological and Social Context. Cambridge, Peabody Museum of Archaeology and Ethnology.
Lang, Richard and Arthur Harris. 1984. The Faunal Remains From Arroyo Hondo Pueblo, New Mexico: A Study in Short- Term Subsistence Change. Santa Fe, School of American Research Press.
McCaffery, Harlan, Robert H. Tykot, Kathy Durand Gore and Beau R. DeBoer. 2014. Stable Isotope Analysis of Turkey (Meleagris Gallopavo) Diet from Pueblo II and Pueblo III Sties, Middle San Juan Region, Northwest New Mexico. American Antiquity 79(2): 337-352.
Rawlings, Tiffany A. and Jonathan C. Driver. 2010. Paleodiet of domestic turkey, Shields Pueblo (5MT3807), Colorado: isotopic analysis and its implications for care of a household domesticate. Journal of Archaeological Science 37: 2433-2441.
Speller, Camilla F., Brian M. Kemp, Scott D. Wyatt, Cara Monroe, William D. Lipe, Ursula M. Arndt and Dongya Y. Yang. 2010. Ancient mitochondrial DNA analysis reveals complexity of indigenous North American turkey domestication. Proceedings of the National Academy of Sciences 107(7): 2807-2812.
Christine Bassett is currently a graduate student working with Fred Andrus in the Department of Geological Sciences at the University of Alabama and holds a B.A. in Anthropology and a B.S. in Geology from the University of Georgia, US. This post is based on research for her M.S. in Geology at Alabama.
Sclerochronology and Paleoenvironmental Reconstruction in the North Pacific Ocean
The archaeological record reflects fluctuating marine conditions from the Aleutian Islands to the Northwest coast of North America during the Late Holocene (Wanner et al., 2008). Though not widely tested, recent research suggests that conditions may have cooled enough during the Late Holocene cold phase to allow sea ice to accumulate as far south as the Northern Pacific Ocean. My research is focused on establishing sclerochronological analysis of Saxidomus gigantea as a means of detecting differences in sea surface temperatures in the Northern Pacific Ocean. Sclerochronological and isotopic analysis of skeletal carbonates can provide a proxy for sea surface temperatures as well as the length of seasons during the recent geological record. My research will contribute to a larger project focusing on human and animal adaptation to climate change led by Fred Andrus (Univerisity of Alabama), Catherine West (Boston University), and Mike Etnier (Portland State University) by providing an additional proxy for reconstructing environmental conditions in the Late Holocene.
Sclerochronology is the study of the growth of invertebrate skeletons. I work exclusively with bivalves, whose distinct growth lines mark regular biologically and environmentally controlled growth intervals (Hallmann et al., 2009). Isotopic analysis of oxygen (δ18O) from growth lines can identify winter growth bands between successive growing seasons. Nadine Hallman and her colleagues (2009) examined the life history of S. giganteus and compared shell precipitation during the organism’s life with oxygen isotopic analysis. They determined that dark bands (Fig. 1) largely co-occurred with peaks in δ18O (Fig. 2). These dark bands mark the beginning and end of a season of growth and the interval between them represent the length of one growing season.
Measuring and comparing the lengths of seasonal shell growth from shells collected at higher latitudes with shells collected from slightly lower latitudes could provide a means of assessing changes in the length of growth seasons, possibly indicating differential sea surfaces temperatures between latitudes. Applying this method to ancient archaeological shells would allow me to test for changes in the length of growing season and by extension, the presence of cold conditions – and possibly sea ice – in the Northern Pacific Ocean during the Late Holocene.
To accomplish this, I plan to collect samples of Saxidomus gigantea from Alaska and Northern British Columbia (Fig. 3). I will analyze δ18O profiles across the organism’s second or third year of growth, the most ontogenetically reliable period of growth, to determine that winter growth bands correspond to peaks in δ18O so that later sclerochronological analysis can be performed. For sclerochronological analysis, I will prepare acetate peels (Fig. 4) so that I can then count lunar-daily growth lines between winter growth bands to quantitatively measure the length of the growing season. Assuming I can detect a difference in the length of the growing season between samples collected at different latitudes, I will apply the same method to ancient samples from the same regions. If the method tested here is successful, sclerochronological analysis of bivalves may be able to contribute to δ18O data interpretation and comparative studies with other organisms to provide a more comprehensive view of changes in SST through recent geological history. Understanding climate in the past contributes greatly to archaeological research that seeks to understand how human behavior, particularly the exploitation of floral and faunal resources, changes as components of the environment change.
Hallmann, N., Burchell, M., Schone, B.R., Irvine, G.V., Maxwell, D., 2009, High-resolution sclerochronological analysis of the bivalve mollusk Saxidomus gigantea from Alaska and British Columbia: techniques for revealing environmental archives and archaeological seasonality. Journal of Archaeological Science, v. 36, pp. 2353-2364.
Wanner, H., Beer, J., Butikofer, J., Crowley, T.J., Cubasch, U., Fluckiger, J., Goosse, H., Grosjean, M., Joos, F., Kaplan, J.O., Kuttel, M., Muller, S.A., Prentice, C., Solomina, O., Stocker, T.F., Tarasov, P., Wagner, M., and Widmann, M., 2008, Mid- to Late Holocene climate change: an overview. Quaternary Science Reviews, v. 27, no. 19-20, pp. 1791-1828.
Planning is currently underway, and further information regarding abstract submission, registration, and travel will be available via the conference website, currently in development.
If you have any questions or would like to be involved in organization, please don’t hesitate to get in touch with the group coordinators, Suzanne Pilaar Birch (sepbirch[at]uga.edu) and Catherine West (cfwest[at]bu.edu).
The 12th International Council for Archaeozoology meeting took place just a little over a month ago in San Rafael, Argentina. I submitted a report on the results of the Stable Isotopes in Zooarchaeology Working Group meeting for the Fall 2014 edition of the ICAZ newsletter, due out shortly and reproduced below.
The meeting was a great success, with lots of interesting papers combining stable isotope methods with a variety of osteological analyses. One of the sessions I gave a paper in was “Stories Written in Teeth”, organized by Florent Rivals, which had papers ranging from serial and bulk sampling of teeth for stable isotope analysis, meso- and microwear studies, cementochronology, and oral pathology, among others. I also attended “Recent Advances in Biomolecular Archaeology”, which also had some good stable isotope papers in addition to DNA-focused ones, and was organized by Jessica Metcalf and Ross Barnett. The opening reception and banquet dinner were highlights. And of course, no conference would be complete without a stop at the local natural history museum.
For those who follow the working group but aren’t ICAZ members (recommended!) I’m reproducing that text here:
Members of the Stable Isotopes in Zooarchaeology (SIZ) Working Group came together for the first time since the group’s formation as a result of the “Integrating Zooarchaeology and Stable Isotope Analyses” conference held at Cambridge University in June 2012. We’ve grown to just about 100 members, and welcomed Catherine West (Department of Archaeology, Boston University) on board as a joint group coordinator. We discussed the development of our existing group website, including the addition of a “Project Page” that will highlight ongoing research projects integrating zooarchaeology and stable isotope analyses and will serve as a resource for students and potential research collaborators. In addition, the website already features a blog, which is always open to new content! [We’re currently looking for submissions, so please do get in touch!]
Another main point of discussion was the date and venue for the upcoming working group meeting, slated for early in 2016. Keep an eye out for an announcement in the Spring newsletter with further details! Finally, the formation of a Faunal Stable Isotope Database, to be integrated with the Neotoma Paleoecology Database (neotomadb.org), was discussed. At this point in time the discussion concerns types of data to be included, data format, and protocols surrounding submission to the database. Interested members of the working group will be involved in these larger issues, while 2-3 data stewards would be directly involved in data management as development progresses.
The Stable Isotopes in Zooarchaeology Working Group will be having a meeting during the upcoming ICAZ conference in San Rafael, Argentina, 22-27 September 2014. We will meet on Wednesday afternoon, from 17:50 – 19:10 (5:50 PM-7:10 PM) in Auditorio B at the Convention Center. Points to be discussed include future working group meetings, group organization, and the creation and management of a stable isotope database that will be linked to the Neotoma Paleoecology Database (Geochemistry and Isotopes Workgroup). See you there!