Isotope evidence for agricultural extensification reveals how the world’s first cities were fed
A. Styring
, M. Charles, F. Fantone, M. M. Hald, A. McMahon, R. H. Meadow, G. K. Nicholls, A. K. Patel, M. C. Pitre, A. Smith, A. Sołtysiak, G. Stein, J. A. Weber, H. Weiss and A. Bogaard. Nature Plants, 3, 17076.


This study sheds light on the agricultural economy that underpinned the emergence of the first urban centres in northern Mesopotamia. Using δ13C and δ15N values of crop remains from the sites of Tell Sabi Abyad, Tell Zeidan, Hamoukar, Tell Brak and Tell Leilan (6500–2000 cal BC), we reveal that labour intensive practices such as manuring/middening and water management formed an integral part of the agricultural strategy from the seventh millennium BC. Increased agricultural production to support growing urban populations was achieved by cultivation of larger areas of land, entailing lower manure/midden inputs per unit area—extensification. Our findings paint a nuanced picture of the role of agricultural production in new forms of political centralisation. While the shift towards lower input farming most plausibly developed gradually at a household level, the increased importance of land-based wealth constituted a key potential source of political power, providing the possibility for greater bureaucratic control and contributing to the wider societal changes that accompanied urbanisation.

Centralisation and long-term change in farming regimes: Comparing agricultural practices in Neolithic and Iron Age south-west Germany.
A. Styring, M. Rösch, E. Stephan, H.-P. Stika, E. Fischer, M. Sillmann and A. Bogaard. Proceedings of the Prehistoric Society.


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.


Cultivation of choice: new insights into farming practices at Neolithic lakeshore sites
A. Styring, U. Maier, E. Stephan, H. Schlichtherle and A. Bogaard. Antiquity, 90, 95-110.


The high-quality organic preservation at Alpine lakeshore settlement sites allows us to go beyond simplistic reconstructions of farming in the Neolithic. The rich archaeological datasets from these sites may be further complemented by methods such as nitrogen isotope (δ15N) analysis of charred crop remains. At Hornstaad-Hörnle IA and Sipplingen, on the shore of Lake Constance in south-west Germany, this method has been used to provide a unique insight into strategies of cultivation such as manuring on both a spatial and temporal scale.

From traditional farming in Morocco to early urban agroecology in Northern Mesopotamia: combining present-day arable weed surveys and crop isotope analysis to reconstruct past agrosystems in (semi-)arid regions.
A. Bogaard, A. Styring, M. Ater, Y. Hmimsa, L. Green, E. Stroud, J. Whitlam, C. Diffey, E. Nitsch, M. Charles, G. Jones and J. Hodgson. Environmental Archaeology.


We integrate functional weed ecology with crop stable carbon and nitrogen isotope analysis to assess their combined potential for inferring arable land management practices in (semi-)arid regions from archaeobotanical assemblages. Weed and GIS survey of 60 cereal and pulse fields in Morocco are combined with crop sampling for stable isotope analysis to frame assessment of agricultural labour intensity in terms of manuring, irrigation, tillage and hand-weeding. Under low management intensity weed variation primarily reflects geographical differences, whereas under high management intensity fields in disparate regions have similar weed flora. Manured and irrigated oasis barley fields are clearly discriminated from less intensively manured rain-fed barley terraces in southern Morocco; when fields in northern and southern Morocco are considered together, climatic differences are superimposed on the agronomic intensity gradient. Barley δ13C and δ15N values clearly distinguish among the Moroccan regimes. An integrated approach combines crop isotope values with weed ecological discrimination of low- and high-intensity regimes across multiple studies (in southern Morocco and southern Europe). Analysis of archaeobotanical samples from EBA Tell Brak, Syria suggests that this early city was sustained through extensive (low-intensity, large-scale) cereal farming.

Siegeszug der Kulturpflanzen – Anbau und Ernährung im Neolithikum
A. Bogaard and A. Styring. Archäologie in Deutschland, 4, 22-23. [translation by C. Knipper]


Umweltbedingungen und Anbaumethoden der vom Menschen kultivierten Nahrungspflanzen erschloss man bisher anhand der Unkrautflora. Neuerdings liefern Untersuchungen der Kohlenstoff- und Stickstoffisotopen in Überresten verkohlter Kulturpflanzen weiterreichende Informationen. Außerdem geben sie Hinweise für die Rekonstruktion der Ernährung.

The stable carbon and especially nitrogen isotope values of charred crop remains complement evidence of growing conditions and arable land management practices from ancient weed flora. They also provide a step forward in the reconstruction of ancient food webs.

The Bandkeramik settlement of Vaihingen an der Enz, Kreis Ludwigsburg (Baden-Württemberg): an integrated perspective on land use, economy and diet.
A. Bogaard, R.-M. Arbogast, R. Ebersbach, R. A. Fraser, C. Knipper, C. Krahn, M. Schäfer,
A. Styring and R. Krause. Germania, 94, 1-60.


In this paper we develop an integrated perspective on land use, economy and diet at the LBK site Vaihingen an der Enz, an extensively excavated settlement and cemetery of the early Neolithic (later 6th millennium cal BC). We synthesise the results of primary and stable isotope analysis of fauna, humans and botanical remains, interpreted in light of material culture variation across the settlement and through the occupation sequence. Our integrated approach reveals a dynamic relationhip between the changing scale and social geography of the community, on the one hand, and land use, on the other.

Disentangling the effect of farming practice from aridity on crop stable isotope values: A present-day model from Morocco and its application to early farming sites in the eastern Mediterranean.
A. Styring, M. Ater, Y. Hmimsa, R. Fraser, H. Miller, R. Neef, J. Pearson and A. Bogaard. The Anthropocene Review, 3, 2-22.


Agriculture has played a pivotal role in shaping landscapes, soils and vegetation. Developing a better understanding of early farming practices can contribute to wider questions regarding the long-term impact of farming and its nature in comparison with present-day traditional agrosystems. In this study we determine stable carbon and nitrogen isotope values of barley grains from a series of present-day traditionally managed farming plots in Morocco, capturing a range of annual rainfall and farming practices. This allows a framework to be developed to refine current isotopic approaches used to infer manuring intensity and crop water status in (semi-)arid regions. This method has been applied to charred crop remains from two early farming sites in the eastern Mediterranean: Abu Hureyra and ‘Ain Ghazal. In this way, our study enhances knowledge of agricultural practice in the past, adding to understanding of how people have shaped and adapted to their environment over thousands of years.

Combining functional weed ecology and crop stable isotope ratios to identify cultivation intensity: a comparison of cereal production regimes in Haute Provence, France and Asturias, Spain.
A. Bogaard, J. Hodgson, E. Nitsch, G. Jones, A Styring, C. Diffey , J. Pouncett, C. Herbig, M. Charles, F. Ertug, O. Tugay, D. Filipovic and R. Fraser. Vegetation History and Archaeobotany, 25, 57-73.


This investigation combines two independent methods of identifying crop growing conditions and husbandry practices—functional weed ecology and crop stable carbon and nitrogen isotope analysis—in order to assess their potential for inferring the intensity of past cereal production systems using archaeobotanical assemblages. Present-day organic cereal farming in Haute Provence, France features crop varieties adapted to low-nutrient soils managed through crop rotation, with little to no manuring. Weed quadrat survey of 60 crop field transects in this region revealed that floristic variation primarily reflects geographical differences. Functional ecological weed data clearly distinguish the Provence fields from those surveyed in a previous study of intensively managed spelt wheat in Asturias, north-western Spain: as expected, weed ecological data reflect higher soil fertility and disturbance in Asturias. Similarly, crop stable nitrogen isotope values distinguish between intensive manuring in Asturias and long-term cultivation with minimal manuring in Haute Provence. The new model of cereal cultivation intensity based on weed ecology and crop isotope values in Haute Provence and Asturias was tested through application to two other present-day regimes, successfully identifying a high-intensity regime in the Sighisoara region, Romania, and low-intensity production in Kastamonu, Turkey. Application of this new model to Neolithic archaeobotanical assemblages in central Europe suggests that early farming tended to be intensive, and likely incorporated manuring, but also exhibited considerable variation, providing a finer grained understanding of cultivation intensity than previously available.


Refining human palaeodietary reconstruction using amino acid δ15N values of plants, animals and humans.
A. Styring, R. Fraser, R-M. Arbogast, P. Halstead, V. Isaakidou, J. Pearson, M. Schäfer, S. Triantaphyllou, S.M. Valamoti, M. Wallace, A. Bogaard and R. P. Evershed. Journal of Archaeological Science, 53, 504-515.


• Human and faunal bone collagen amino acid (AA) δ15N values were determined.
• We compared 4 diet reconstruction methods using bone collagen and plant δ15N values.
• Different dietary protein estimates are made when grain δ15N values are considered.
• Further investigation is needed into AA δ15N values in terrestrial ecosystems.


The effect of manuring on cereal and pulse amino acid δ15N values.
A. Styring, R. Fraser, A. Bogaard and R. P. Evershed. Phytochemistry, 102, 40-45.


• Manured and unmanured crop amino acid δ15N values were determined by GC-C-IRMS.
• Manuring of cereals increases the δ15N values of all grain and rachis amino acids.
• Manuring does not change the relative δ15N values of cereal grain amino acids.
• Rachis amino acid δ15N values vary more with manuring than grains from the same plots.
• Pulses did not assimilate significant N from manure.

Cereal grain, rachis and pulse seed amino acid δ15N values as indicators of plant nitrogen metabolism.
A. Styring, R. Fraser, A. Bogaard and R. P. Evershed. Phytochemistry, 97, 20-29.


• Plant amino acid δ15N values were determined by GC–C–IRMS.
• Cereal grain amino acid δ15N values reflect known amino acid biosynthetic pathways.
• Cereal rachis amino acid δ15N values reflect known amino acid biosynthetic pathways.
• Relative amino acid δ15N values of broad bean and pea seeds differ.


The effect of charring and burial on the biochemical composition of cereal grains: Investigating the integrity of archaeological plant material.
A. Styring, H. Manning, R. Fraser, M. Wallace, G. Jones, M. Charles, T. Heaton, A. Bogaard and R. P. Evershed. Journal of Archaeological Science, 40, 4767-4779.

Assessing natural variation and the effects of charring, burial and pre-treatment on the stable carbon and nitrogen isotope values of archaeobotanical cereal and pulse remains.
R. Fraser, A. Bogaard, M. Charles, A. Styring, M. Wallace, G. Jones, P. Ditchfield and T. Heaton. Journal of Archaeological Science, 40, 4754-4766.


• These two studies investigate the effect of heating on the δ13C and δ15N values and the biochemical composition of cereal grains.
• They also investigate the effects of the acid-base-acid pretreatment method.
• Charring has negligible effect on δ13C values but can increase δ15N values
• Ancient charred einkorn grains consist of aromatic carbon and retain their nitrogen.

Crop manuring and intensive land management by Europe’s first farmers
A. Bogaard, R. Fraser, T. Heaton, M. Wallace, P. Vaiglova, M. Charles, G. Jones, R. Evershed, A. Styring, N. Andersen, R-M. Arbogast, L. Bartosiewicz, A. Gardeisen, M. Kanstrup, U. Maier, E.Marinova, L. Ninov, M. Schäfer and E. Stephan. Proceedings of the National Academy of Sciences, 110, 12589-12594


The spread of farming from western Asia to Europe had profound long-term social and ecological impacts, but identification of the specific nature of Neolithic land management practices and the dietary contribution of early crops has been problematic. Here, we present previously undescribed stable isotope determinations of charred cereals and pulses from 13 Neolithic sites across Europe (dating ca. 5900–2400 cal B.C.), which show that early farmers used livestock manure and water management to enhance crop yields. Intensive manuring inextricably linked plant cultivation and animal herding and contributed to the remarkable resilience of these combined practices across diverse climatic zones. Critically, our findings suggest that commonly applied paleodietary interpretations of human and herbivore δ15N values have systematically underestimated the contribution of crop-derived protein to early farmer diets.


Practical considerations in the determination of compound-specific amino acid δ15N values in animal and plant tissues by gas chromatography-combustion-isotope ratio mass spectrometry, following derivatisation to their N-acetylisopropyl esters.
A. Styring, A. Kuhl, T. Knowles, R. Fraser, A. Bogaard and R. Evershed. Rapid Communications in Mass Spectrometry, 26, 2328-2334.


Stable nitrogen isotope (δ15N) values of bone collagen are routinely used to inform interpretations of diet and trophic positions within contemporary and ancient ecosystems, yet the underlying physiological and biochemical factors which contribute to the bulk collagen δ15N value remain little understood. Determination of individual amino acid (AA) δ15N values in animal and plant proteins can help to elucidate the cycling of nitrogen and inform predictions of palaeodiet and ecology.

We conclude that hydrolysis of lipid-extracted plant material followed by purification of AAs using Dowex ion-exchange resin and derivatisation to their N-acetylisopropyl esters is a suitable protocol for the accurate determination of individual plant and animal AA δ15N values by GC-C-IRMS.


Manuring and stable nitrogen isotope ratios in cereals and pulses: towards a new archaeobotanical approach to the inference of land use and dietary practices.
R. Fraser, A. Bogaard, T. Heaton, M. Charles, G. Jones, B. Christensen, P. Halstead, I. Merbach, P. Poulton, D. Sparkes and A. Styring. Journal of Archaeological Science, 38, 2790-2804.


This paper explores the impact of animal manure application on the δ15N values of a broad range of crops (cereals and pulses), under a range of manuring levels/regimes and at a series of locations extending from northwest Europe to the eastern Mediterranean. We included both agricultural field experiments and areas where ‘traditional’ farming is practised. Our aim is to ground-truth interpretation of δ15N values in archaeobotanical crop remains as evidence of past growing conditions and husbandry practices. The results confirm the potentially radical impact of manuring on δ15N values in cereals, depending on manuring level, but indicate only a slight effect on pulses, which can fix atmospheric nitrogen. The expected geographical trend towards greater δ15N with increasing climatic aridity is not apparent, probably because the growing conditions for crops are ‘buffered’ through crop management. Each of these observations has fundamental implications for archaeobotanical interpretation of δ15N values as evidence of land use practices and (together with analysis of bone collagen/tooth enamel in potential consumers) palaeodiet.


Resolving the bulk δ15N values of ancient human and animal bone collagen via compound-specific nitrogen isotope analysis of constituent amino acids.
A. Styring, J. Sealy and R. Evershed. Geochimica et Cosmochimica Acta, 74, 241-251.


In order to assess more fully the dietary contributions to human tissue δ15N values, a greater understanding of the complex biochemical and physiological factors which underpin bulk collagen δ15N values is necessary. Determinations of δ15N values of the individual amino acids which constitute bone collagen are necessary to unravel these relationships, since different amino acids display different δ15N values according to their biosynthetic origins.

A range of collagen isolates from archaeological faunal and human bone, representing a spectrum of terrestrial and marine protein origins and diets, were selected from coastal and near-coastal sites at the south-western tip of Africa. The δ15N values of individual amino acids provide insights into both the contributions of various amino acids to the bulk δ15N value of collagen and the factors influencing trophic position and the nitrogen source at the base of the food web. The contributions of marine and terrestrial protein to diet are strongly reflected in Δ15NGlu-Phevalues. Differences in nitrogen metabolism are also shown to have an influence upon individual amino acid δ15N values with Δ15NGlu-Phe values emphasising differences between the different physiological adaptations. The latter is demonstrated in tortoises, which can excrete nitrogen in the form of uric acid and urea and display negative Δ15NGlu-Phe values whereas those for marine and terrestrial mammals are positive. The findings amplify the potential advantages of compound-specific nitrogen isotope analysis in the study of nitrogen flow within food webs and in the reconstruction of past human diets.