Variability of diet in human populations of the Near East from the Neolithic to the Modern period: an application of stable carbon and nitrogen isotope analysis (2013–2016) (NCN HARMONIA, 2012/06/M/HS3/00272)

Research on stable carbon and nitrogen isotopic proportions in human collagen is a standard tool in investigation of diet and subsistence in past human societies. Proportions of carbon isotopes (13C to 12C) may be used to estimate share in diet of some plants with a specific photosyntesis pathway (like maize, millet, sorghum or sugarcane) or to distinguish between marine and terrestrial diets. Proportions of nitrogen isotopes (15N to 14N) are correlated with the trophic level, so the share of animal-related products in diet may be investigated.

Although research on stable carbon and nitrogen isotopes was introduced to archaeology more than 30 years ago, this method has atracted little attention of archaeologists working in the Near East. The project aims to fill this gap at least partially, providing results of isotopic research on human remains from nine archaeological sites in Northern Mesopotamia. Large dataset including several chronological units from three different ecological zones enabled some insight into changes in diet and subsistence from the Bronze Age to the Modern period.

More specifically, there are two most important results of the project. First, small but significant shift in carbon isotopic values has been observed at many sites during the second millennium BCE. As no new crops were introduced in that time, this shift was most likely the result of wider use of dry steppes for pastures of caprovid flocks. The isotopic bulk signature of wild grasses, different from domesticated cereals, was transferred to humans through animal products in diet. This shift in animal husbandry seems to reflect the broader change in social organization, with higher independence of pastoralists from the state.

Another interesting result is the dating of the large irrigation system in the middle Euphrates valley south of the Khabour confluence. Lower water stress and more extensive plant cultivation on widely irrigated fields changed the nitrogen isotopic values between the Middle Bronze Age and the Neo-Assyrian period and it is most likely that the construction of irrigation canals was a part of Assyrian policy of increasing the agricultural potential of the empire.

All these results are important for better understanding of the social and economic history of ancient Mesopotamia, but can have also broader impact on bioarchaeological methods and theory. For example, observed correlation between nitrogen isotopic values and annual precipitation allows use of the former as the proxy indicator of mobility between more dry and more humid locations.

The impact of the environment on the process of urbanisation in Late Chalcolithic Syria: the analysis of mass burials at Tell Majnuna (2014–2016) (NCN HARMONIA, 2013/10/M/HS3/00554)

Tell Brak is an important archaeological site in Syria, with evidence of early urbanisation as early as in the end of 5th millennium BCE. At one of satellite mounds of this site called Tell Majnuna, a large midden has been found together with several clusters of partially or totally disarticulated human remains as well as a regular cemetery on the top.

At least two largest clusters, with evidence of stress, disarticulation and scavenging, seem to reflect two episodes of increased mortality that could have been caused by warfare, famine or epidemic disease. The project aims to check the hypothesis that the earliest event reflected by the largest cluster of human remains was preceded by a period of environmental stress related to drought and food shortage. To answer this question, several analytical methods are used, as study of micro- and macrodefects in the incremental layers of enamel, analysis of the sequence of oxygen isotopic values in enamel, research on enamel microwear patterns, and radiocarbon dating of human bones from several contexts.

Combined study of enamel defects and oxygen isotopic values produced significant results and at least two periods of prolonged drought and environmental stress were detected. One of them started c. 4.5 years before the event of increased mortality and directly preceded mass death, and another one occured c. 10-15 years before. It means that the early urban society was sensitive to short-term climatic fluctuations and the general level of stress was relatively high, that is indicated also by high frequency of cranial trauma and a case of child abuse found in a bit earlier cemetery at Tell Brak.

The project provided new data for the discussion about the background of rapid urbanization at Tell Brak in late 5th and early 4th millennium BCE. It also introduced some new analytical methods that allow relatively precise reconstruction of environmental history for c. 30-35 years prior to an episode of increased mortality leading to formation of a mass burial.

Pattern of human migrations in Iran from Chalcolithic to the age of great empires (2017–2020) (NCN, HARMONIA, 2016/22/M/HS3/00353)

Human mobility (including mass migrations) is traditionally an important area of research for archaeologists who try to reconstruct behaviour of past human groups. Traditional archaeological toolkit in research on mobility includes search for style influences and analysis of spatial and temporal distribution of particular artifacts, as e.g. famous Naue II swords in the Late Bronze Age and Iron Age Europe. However, the output of these methods is always disputable and speculative. On the other hand, bioarchaeology (and more specifically research on human remains from archaeological sites) offers direct and therefore much more reliable insight into patterns of mobility in the past.

Within the current project we intend to estimate patterns of mobility in three major phases of social and political development in ancient Iran, i.e. early urban development during the Late Chalcolithic and Early/Middle Bronze Age (c. 4000-1800/1500 BCE), the transitional period (c. 1800/1500-700 BCE) and the period when great empires developed in the Near/Middle East (after c. 700 BCE).

The principal method will be the analysis of strontium isotope ratios ( 87 Sr/ 86 Sr ) in human bioapatite against environmental background. As strontium isotopic values differ between locations with different geological background, in many cases it is possible at least to distinguish between individuals that were born in the area where they were buried from people that migrated during their lifetime. Sometimes it is even possible to estimate the area of origin and some transitional locations. As the area of Iran is highly variable in respect on environmental conditions (humidity and available plant resources), also isotopic indicators of diet may be used as the proxy indicator of mobility.

Therefore, the secondary method will be research on carbon ( δ 13 C) and nitrogen ( δ 15 N) stable isotope ratios in human collagen. The isotopic methods are useful in tracing individual mobility. To have also insight into general migrations, we will analyse ancient nuclear and mitochondrial DNA polymorphisms and dental non-metric traits that may offer some insight into general affinities of studied human populations and reveal general directions of mass migrations. Due to large scale of the project (up to 900 individuals studied), its output may contribute a lot to our knowledge of prehistory and early history of Iran.

Advanced methods of diet analysis in past human populations (2016–2019) (MNiSW, 2bH 15 0038 83)

The aim of the project is to develop new methods of diet analysis using bone and dental tissue (bioapatite, collagen and dental calculus). First topic is the seasonal variation of individual diet during the first years of his life based on stable carbon, strontium and oxygen isotope values in incremental layers of tooth enamel. Second topic is the carbon and oxygen isotope analysis of starch granules embedded into human dental calculus. This material is usually not accessible for the isotopic study due to poor preservation of starches in plant remains retrieved from archaeological strata. The analysis of starch granules in dental calculus, which are relatively often present there, may help to fill out this gap. Third topic is the development of a noninvasive method of estimating the organic fraction content in bone tissue using combined neutron and X-ray radiography. In future this method may help to preselect particularly valuable museum materials for a destructive research.

The project allows to develop and test new research tools for reconstructing diet and subsistence in past human populations. The application of a new, high resolution method will allow to conduct more precise study of changes during ontogenesis, including the duration of breastfeeding and weaning age as well as the seasonal variation in diet. The analysis of starch grains in dental calculus will help to understand isotopic variation in consumed plants, e.g. due to their growth conditions. Noninvasive analysis of collagen preservation in bone tissue may support selection of bone samples not only for the analysis of diet, but also for any other research using bone collagen.