Amy Styring | Goethe-Universität Frankfurt am Main (original) (raw)
Papers by Amy Styring
Vegetation History and Archaeobotany, 2019
The nitrogen isotope compositions of charred wheat and barley grains reflect manuring intensity a... more The nitrogen isotope compositions of charred wheat and barley grains reflect manuring intensity and have been used to
reconstruct past manuring practices at archaeological sites across Europe and western Asia. To assess whether this analytical
method can be applied to a staple crop in the West African Sahel, the nitrogen isotope values of Pennisetum glaucum
grains in this region were determined and the effect of charring ascertained. Pennisetum glaucum ears were collected from
fields in northeast Senegal, where the fertilisation histories of the plots (manure and/or household waste) were known. The
nitrogen isotope values of these millet grains provide an insight into the values to expect for P. glaucum grains grown with
low to moderate addition of manure/household waste in a semi-arid climate. Charring of P. glaucum grains by heating at
215–260 °C for 4–24 h increases their nitrogen isotope values by a maximum of 0.34‰. In light of these modern data, the
nitrogen isotope values of millet grains recovered from the archaeological settlement mound of Tongo Maaré Diabal, Mali,
can be interpreted as evidence for modest levels of manure/household waste input throughout the occupation of the site
from cal ad 500–1150. This study demonstrates the potential for nitrogen isotope values of P. glaucum grains to shed light
on past farming practices in West Africa.
We integrate functional weed ecology with crop stable carbon and nitrogen isotope analysis to as... more 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 .
"This study sheds light on the agricultural economy that underpinned the emergence of the first u... more "This study sheds light on the agricultural economy that underpinned the emergence of the first urban centres in northern Mesopotamia. Using δ 13 C and δ 15 N 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 centralization. The shift towards lower-input farming most plausibly developed gradually at a household level, but 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 urbanization."
The high-quality organic preservation at Alpine lakeshore settlement sites allows us to go beyond... more 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.
In this paper we develop an integrated perspective on land use, economy and diet at the LBK site ... more 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.
Agriculture has played a pivotal role in shaping landscapes, soils and vegetation. Developing a b... more 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.
Vegetation History and Archaeobotany, 2015
This investigation combines two independent methods of identifying crop growing conditions and hu... more 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.
The spread of farming from western Asia to Europe had profound long-term social and ecological im... more 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 δ 15 N values have systematically underestimated the contribution of crop-derived protein to early farmer diets. agriculture | prehistoric | husbandry | paleodiet
Journal of Archaeological Science, 2013
Stable isotope analysis of charred archaeobotanical cereal grains has the potential to provide di... more Stable isotope analysis of charred archaeobotanical cereal grains has the potential to provide direct evidence of crop growing conditions in the past and to refine palaeodietary predictions. If isotope values of archaeobotanical material are to be considered robust, it is necessary to characterise the compositional changes associated with their charring and burial. This study used a suite of analytical techniques, including FT-IR and solid state 13C NMR, to characterise changes in the biochemical composition of modern einkorn grains with heating at 230 C for 2 h, 4 h, 8 h and 24 h, encompassing conditions that replicate their undistorted ancient counterparts. The biochemical composition of archaeobotanical
charred einkorn grains was also investigated by FT-IR and solid state 13C NMR in order to assess the changes in composition which occur during burial. Results of FT-IR and solid-state 13C NMR show that heating of modern einkorn grains resulted in Maillard reactions between cereal proteins and starch, forming high molecular weight melanoidins, which contain both alkyl and aromatic carbon. Loss of low molecular weight carbon and nitrogen-containing volatiles resulted in a slight but non-systematic increase in the d13C values and a systematic increase of 0.8 per mil in the d15N values of the charred einkorn grains. Solid-state 13C NMR shows that the ancient charred
einkorn grains consisted entirely of aromatic carbon and retained a similar proportion of nitrogen to their modern 24 h charred counterparts, despite a significantly lower concentration of amino acids. This indicates that the amino acid nitrogen was retained in the stable melanoidins whose polymeric structure makes them resistant to subsequent degradation.
The aim of this study is to assess the potential of charred archaeobotanical cereal grain and pul... more The aim of this study is to assess the potential of charred archaeobotanical cereal grain and pulse seed δ13C and δ15N values to provide evidence of crop growing conditions and as a potential component of palaeodietary studies. In order to reliably interpret archaeobotanical δ13C and δ15N values it is necessary to take into account the impact of charring, burial and laboratory pre-treatment procedures. We examine the effects of charring and burial on bulk δ13C, δ15N, %C, %N and C:N ratios in modern cereal and pulse material, and of cleaning by acid–base–acid (ABA) pre-treatment on modern and archaeobotanical charred material. Our study utilised bulk grain and seed samples to help account for within-ear/pod and between-plant variability in δ13C and δ15N values. Heating at relatively low temperatures and for prolonged times (230 °C for up to 24 h) is conducive to the formation of well preserved, undistorted charred cereal grain and pulse seed. Heating for 24 h has a systematic and predictable effect on δ15N values, with increases of around 1‰ on average in cereal grains and pulse seeds, and no consistent impact on δ13C values. Increases in δ15N are likely due to the loss of lighter 14N via N-containing volatiles. Burial (for up to 2 years) and ABA pre-treatment have no significant effects on δ13C or δ15N values. After pre-treatment, however, the %C and %N contents of the archaeobotanical material more closely resembles that of the modern charred grains and seeds, suggesting that archaeobotanical remains accumulate non-structural material during burial but retain their original carbon and nitrogen content. Therefore %C, %N contents and C:N ratios can provide useful criteria for assessing archaeobotanical preservation.
Journal of Archaeological Science, 2011
This paper explores the impact of animal manure application on the δ 15 N values of a broad range... more This paper explores the impact of animal manure application on the δ 15 N 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 δ 15 N values in archaeobotanical crop remains as evidence of past growing conditions and husbandry practices. The results confirm the potentially radical impact of manuring on δ 15 N 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 δ 15 N 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 δ 15 N values as evidence of land use practices and (together with analysis of bone collagen/tooth enamel in potential consumers) palaeodiet.
Amino acid nitrogen isotope values by Amy Styring
Phytochemistry, 2014
a b s t r a c t Amino acid d 15 N values of barley (Hordeum vulgare) and bread wheat (Triticum ae... more a b s t r a c t Amino acid d 15 N values of barley (Hordeum vulgare) and bread wheat (Triticum aestivum) grains and rachis and broad bean (Vicia faba) and pea (Pisum sativum) seeds, grown in manured and unmanured soil at the experimental farm stations of Rothamsted, UK and Bad Lauchstädt, Germany, were determined by GC-C-IRMS. Manuring was found to result in a consistent 15 N-enrichment of cereal grain amino acid d 15 N values, indicating that manuring did not affect the metabolic routing of nitrogen (N) into cereal grain amino acids. The increase in cereal grain d 15 N values with manuring is therefore due to a 15 N-enrichment in the d 15 N value of assimilated inorganic-N. Greater variation was observed in the 15 N-enrichment of rachis amino acids with manuring, possibly due to enhanced sensitivity to changes in growing conditions and higher turnover of N in rachis cells compared to cereal grains. Total amino acid d 15 N values of manured and unmanured broad beans and peas were very similar, indicating that the legumes assimilated N 2 from the atmosphere rather than N from the soil, since there was no evidence for routing of 15 N-enriched manure N into any of the pulse amino acids. Crop amino acid d 15 N values thus provide insights into the sources of N assimilated by non N 2 -fixing and N 2 -fixing crops grown on manured and unmanured soils, and reveal an effect of manure on N metabolism in different crop species and plant parts.
Geochimica et Cosmochimica Acta, Jan 1, 2010
Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and troph... more Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and trophic positions within contemporary and ancient ecosystems. In order to assess more fully the dietary contributions to human tissue isotope 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 (n = 12 and 11, respectively), 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 collagens were hydrolysed and δ15N values of their constituent amino acids determined as N-acetylmethyl esters (NACME) via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The analytical approach employed accounts for 56% of bone collagen nitrogen. Reconstruction of bulk bone collagen δ15N values reveals a 2‰ offset from bulk collagen δ15N values which is attributable to the δ15N value of the amino acids which cannot currently be determined by GC-C-IRMS, notably arginine which comprises 53% of the nitrogen unaccounted for (23% of the total nitrogen). 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 similarity in the δ15N values of alanine, glutamate, proline and hydroxyproline reflects the common origin of their amino groups from glutamate. The depletion in the δ15N value of threonine with increasing trophic level indicates a fundamental difference between the biosynthetic pathway of threonine and the other amino acids. The δ15N value of phenylalanine does not change significantly with trophic level, reflecting its conservative nature as an essential amino acid, and thus represents the isotopic composition of the nitrogen at the base of the food web. Δ15NGlu-Phe values in particular are shown to reflect trophic level nitrogen sources within a food web. In relation to the reconstruction of ancient human diet the contribution of marine and terrestrial protein are strongly reflected in Δ15NGlu-Phe values. 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.
RATIONALEStable nitrogen isotope (δ15N) values of bone collagen are routinely used to inform inte... more RATIONALEStable 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.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.METHODSIn this study we present a methodology for the measurement of amino acid δ15N values using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Amino acid standards of known δ15N values were derivatised to their N-acetylisopropyl (NAIP) esters and purified through Dowex ion-exchange resin to determine any isotopic fractionation associated with derivatisation and ion-exchange chromatography. The effect of starch on AA δ15N values was also determined by hydrolysing bone collagen with and without the presence of starch.In this study we present a methodology for the measurement of amino acid δ15N values using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Amino acid standards of known δ15N values were derivatised to their N-acetylisopropyl (NAIP) esters and purified through Dowex ion-exchange resin to determine any isotopic fractionation associated with derivatisation and ion-exchange chromatography. The effect of starch on AA δ15N values was also determined by hydrolysing bone collagen with and without the presence of starch.RESULTSThe amino acids derivatised to their NAIP esters give values within ±0.8‰ of their δ15N values measured separately by elemental analyser (EA)-IRMS, with a precision of better than 0.8‰. The δ15N values of AAs after Dowex ion-exchange chromatography were within ±0.9‰ of their values prior to ion-exchange chromatography. The AA δ15N values of bone collagen hydrolysed with and without starch were within ±0.8‰.The amino acids derivatised to their NAIP esters give values within ±0.8‰ of their δ15N values measured separately by elemental analyser (EA)-IRMS, with a precision of better than 0.8‰. The δ15N values of AAs after Dowex ion-exchange chromatography were within ±0.9‰ of their values prior to ion-exchange chromatography. The AA δ15N values of bone collagen hydrolysed with and without starch were within ±0.8‰.CONCLUSIONSHydrolysis of lipid-extracted plant material followed by purification of AAs using Dowex ion-exchange resin and derivatisation to their NAIP esters is a suitable protocol for the accurate determination of individual plant and animal AA δ15N values by GC-C-IRMS. Copyright © 2012 John Wiley & Sons, Ltd.Hydrolysis of lipid-extracted plant material followed by purification of AAs using Dowex ion-exchange resin and derivatisation to their NAIP esters is a suitable protocol for the accurate determination of individual plant and animal AA δ15N values by GC-C-IRMS. Copyright © 2012 John Wiley & Sons, Ltd.
Natural abundance d 15 N values of plant tissue amino acids (AAs) reflect the cycling of N into a... more Natural abundance d 15 N values of plant tissue amino acids (AAs) reflect the cycling of N into and within plants, providing an opportunity to better understand environmental and anthropogenic effects on plant metabolism. In this study, the AA d 15 N values of barley (Hordeum vulgare) and bread wheat (Triticum aestivum) grains and rachis and broad bean (Vicia faba) and pea (Pisum sativum) seeds, grown at the experimental farm stations of Rothamsted, UK and Bad Lauchstädt, Germany, were determined by GC-C-IRMS. It was found that the d 15 N values of cereal grain and rachis AAs could be largely attributed to metabolic pathways involved in their biosynthesis and catabolism. The relative 15 N-enrichment of phenylalanine can be attributed to its involvement in the phenylpropanoid pathway and glutamate has a d 15 N value which is an average of the other AAs due to its central role in AA-N cycling. The relative AA d 15 N values of broad bean and pea seeds were very different from one another, providing evidence for differences in the metabolic routing of AAs to the developing seeds in these leguminous plants. This study has shown that AA d 15 N values relate to known AA biosynthetic pathways in plants and thus have the potential to aid understanding of how various external factors, such as source of assimilated N, influence metabolic cycling of N within plants.
Journal of Archaeological Science, 2015
An established method of estimating the trophic level of an organism is through stable isotope an... more An established method of estimating the trophic level of an organism is through stable isotope analysis of its tissues and those of its diet. This method has been used in archaeology to reconstruct past human diet from the stable nitrogen isotope (d 15 N) values of human and herbivore bone collagen. However, this approach, using the 15 N-enrichment of human bone collagen d 15 N values over associated herbivore bone collagen d 15 N values to predict the relative importance of animal protein, relies on the assumptions that: (i) the d 15 N values of plants consumed by humans and herbivores are identical, and (ii) the 15 Nenrichment between diet and consumer is consistent. Bone collagen amino acid d 15 N values have the potential to tackle these uncertainties, as they constrain the factors influencing bone collagen d 15 N values. In this study, the d 15 N values of glutamic acid and phenylalanine in human and herbivore bone collagen isolates from Neolithic sites in Germany, Greece and Turkey were determined by gas chromatography-combustion-isotope ratio mass spectrometry. The fraction of animal protein in total dietary protein consumed by the humans was estimated by: (i) comparing bulk human and herbivore collagen d 15 N values, (ii) comparing bulk human and herbivore collagen and ancient charred cereal grain d 15 N values, (iii) comparing human bone collagen d 15 N Glutamic acid and d 15 N Phenylalanine values, and (iv) comparing d 15 N Glutamic acid values of human and herbivore bone collagen and estimated d 15 N Glutamic acid values of ancient charred cereal grains. Where determined cereal grain d 15 N values are higher than estimated herbivore forage values, estimates of animal protein consumption are significantly lower, emphasising the importance of the plant nitrogen contribution to human bone collagen. This study also highlights the need for further investigation into: (i) the D 15 N Consumer-Diet values of glutamic acid and phenylalanine in terrestrial ecosystems, and (ii) D 15 N Glutamic acid-Phenylalanine values of common plant foods in order to improve the accuracy and more widespread applicability of amino acid-based methods for palaeodietary reconstruction.
Vegetation History and Archaeobotany, 2019
The nitrogen isotope compositions of charred wheat and barley grains reflect manuring intensity a... more The nitrogen isotope compositions of charred wheat and barley grains reflect manuring intensity and have been used to
reconstruct past manuring practices at archaeological sites across Europe and western Asia. To assess whether this analytical
method can be applied to a staple crop in the West African Sahel, the nitrogen isotope values of Pennisetum glaucum
grains in this region were determined and the effect of charring ascertained. Pennisetum glaucum ears were collected from
fields in northeast Senegal, where the fertilisation histories of the plots (manure and/or household waste) were known. The
nitrogen isotope values of these millet grains provide an insight into the values to expect for P. glaucum grains grown with
low to moderate addition of manure/household waste in a semi-arid climate. Charring of P. glaucum grains by heating at
215–260 °C for 4–24 h increases their nitrogen isotope values by a maximum of 0.34‰. In light of these modern data, the
nitrogen isotope values of millet grains recovered from the archaeological settlement mound of Tongo Maaré Diabal, Mali,
can be interpreted as evidence for modest levels of manure/household waste input throughout the occupation of the site
from cal ad 500–1150. This study demonstrates the potential for nitrogen isotope values of P. glaucum grains to shed light
on past farming practices in West Africa.
We integrate functional weed ecology with crop stable carbon and nitrogen isotope analysis to as... more 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 .
"This study sheds light on the agricultural economy that underpinned the emergence of the first u... more "This study sheds light on the agricultural economy that underpinned the emergence of the first urban centres in northern Mesopotamia. Using δ 13 C and δ 15 N 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 centralization. The shift towards lower-input farming most plausibly developed gradually at a household level, but 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 urbanization."
The high-quality organic preservation at Alpine lakeshore settlement sites allows us to go beyond... more 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.
In this paper we develop an integrated perspective on land use, economy and diet at the LBK site ... more 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.
Agriculture has played a pivotal role in shaping landscapes, soils and vegetation. Developing a b... more 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.
Vegetation History and Archaeobotany, 2015
This investigation combines two independent methods of identifying crop growing conditions and hu... more 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.
The spread of farming from western Asia to Europe had profound long-term social and ecological im... more 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 δ 15 N values have systematically underestimated the contribution of crop-derived protein to early farmer diets. agriculture | prehistoric | husbandry | paleodiet
Journal of Archaeological Science, 2013
Stable isotope analysis of charred archaeobotanical cereal grains has the potential to provide di... more Stable isotope analysis of charred archaeobotanical cereal grains has the potential to provide direct evidence of crop growing conditions in the past and to refine palaeodietary predictions. If isotope values of archaeobotanical material are to be considered robust, it is necessary to characterise the compositional changes associated with their charring and burial. This study used a suite of analytical techniques, including FT-IR and solid state 13C NMR, to characterise changes in the biochemical composition of modern einkorn grains with heating at 230 C for 2 h, 4 h, 8 h and 24 h, encompassing conditions that replicate their undistorted ancient counterparts. The biochemical composition of archaeobotanical
charred einkorn grains was also investigated by FT-IR and solid state 13C NMR in order to assess the changes in composition which occur during burial. Results of FT-IR and solid-state 13C NMR show that heating of modern einkorn grains resulted in Maillard reactions between cereal proteins and starch, forming high molecular weight melanoidins, which contain both alkyl and aromatic carbon. Loss of low molecular weight carbon and nitrogen-containing volatiles resulted in a slight but non-systematic increase in the d13C values and a systematic increase of 0.8 per mil in the d15N values of the charred einkorn grains. Solid-state 13C NMR shows that the ancient charred
einkorn grains consisted entirely of aromatic carbon and retained a similar proportion of nitrogen to their modern 24 h charred counterparts, despite a significantly lower concentration of amino acids. This indicates that the amino acid nitrogen was retained in the stable melanoidins whose polymeric structure makes them resistant to subsequent degradation.
The aim of this study is to assess the potential of charred archaeobotanical cereal grain and pul... more The aim of this study is to assess the potential of charred archaeobotanical cereal grain and pulse seed δ13C and δ15N values to provide evidence of crop growing conditions and as a potential component of palaeodietary studies. In order to reliably interpret archaeobotanical δ13C and δ15N values it is necessary to take into account the impact of charring, burial and laboratory pre-treatment procedures. We examine the effects of charring and burial on bulk δ13C, δ15N, %C, %N and C:N ratios in modern cereal and pulse material, and of cleaning by acid–base–acid (ABA) pre-treatment on modern and archaeobotanical charred material. Our study utilised bulk grain and seed samples to help account for within-ear/pod and between-plant variability in δ13C and δ15N values. Heating at relatively low temperatures and for prolonged times (230 °C for up to 24 h) is conducive to the formation of well preserved, undistorted charred cereal grain and pulse seed. Heating for 24 h has a systematic and predictable effect on δ15N values, with increases of around 1‰ on average in cereal grains and pulse seeds, and no consistent impact on δ13C values. Increases in δ15N are likely due to the loss of lighter 14N via N-containing volatiles. Burial (for up to 2 years) and ABA pre-treatment have no significant effects on δ13C or δ15N values. After pre-treatment, however, the %C and %N contents of the archaeobotanical material more closely resembles that of the modern charred grains and seeds, suggesting that archaeobotanical remains accumulate non-structural material during burial but retain their original carbon and nitrogen content. Therefore %C, %N contents and C:N ratios can provide useful criteria for assessing archaeobotanical preservation.
Journal of Archaeological Science, 2011
This paper explores the impact of animal manure application on the δ 15 N values of a broad range... more This paper explores the impact of animal manure application on the δ 15 N 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 δ 15 N values in archaeobotanical crop remains as evidence of past growing conditions and husbandry practices. The results confirm the potentially radical impact of manuring on δ 15 N 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 δ 15 N 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 δ 15 N values as evidence of land use practices and (together with analysis of bone collagen/tooth enamel in potential consumers) palaeodiet.
Phytochemistry, 2014
a b s t r a c t Amino acid d 15 N values of barley (Hordeum vulgare) and bread wheat (Triticum ae... more a b s t r a c t Amino acid d 15 N values of barley (Hordeum vulgare) and bread wheat (Triticum aestivum) grains and rachis and broad bean (Vicia faba) and pea (Pisum sativum) seeds, grown in manured and unmanured soil at the experimental farm stations of Rothamsted, UK and Bad Lauchstädt, Germany, were determined by GC-C-IRMS. Manuring was found to result in a consistent 15 N-enrichment of cereal grain amino acid d 15 N values, indicating that manuring did not affect the metabolic routing of nitrogen (N) into cereal grain amino acids. The increase in cereal grain d 15 N values with manuring is therefore due to a 15 N-enrichment in the d 15 N value of assimilated inorganic-N. Greater variation was observed in the 15 N-enrichment of rachis amino acids with manuring, possibly due to enhanced sensitivity to changes in growing conditions and higher turnover of N in rachis cells compared to cereal grains. Total amino acid d 15 N values of manured and unmanured broad beans and peas were very similar, indicating that the legumes assimilated N 2 from the atmosphere rather than N from the soil, since there was no evidence for routing of 15 N-enriched manure N into any of the pulse amino acids. Crop amino acid d 15 N values thus provide insights into the sources of N assimilated by non N 2 -fixing and N 2 -fixing crops grown on manured and unmanured soils, and reveal an effect of manure on N metabolism in different crop species and plant parts.
Geochimica et Cosmochimica Acta, Jan 1, 2010
Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and troph... more Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and trophic positions within contemporary and ancient ecosystems. In order to assess more fully the dietary contributions to human tissue isotope 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 (n = 12 and 11, respectively), 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 collagens were hydrolysed and δ15N values of their constituent amino acids determined as N-acetylmethyl esters (NACME) via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The analytical approach employed accounts for 56% of bone collagen nitrogen. Reconstruction of bulk bone collagen δ15N values reveals a 2‰ offset from bulk collagen δ15N values which is attributable to the δ15N value of the amino acids which cannot currently be determined by GC-C-IRMS, notably arginine which comprises 53% of the nitrogen unaccounted for (23% of the total nitrogen). 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 similarity in the δ15N values of alanine, glutamate, proline and hydroxyproline reflects the common origin of their amino groups from glutamate. The depletion in the δ15N value of threonine with increasing trophic level indicates a fundamental difference between the biosynthetic pathway of threonine and the other amino acids. The δ15N value of phenylalanine does not change significantly with trophic level, reflecting its conservative nature as an essential amino acid, and thus represents the isotopic composition of the nitrogen at the base of the food web. Δ15NGlu-Phe values in particular are shown to reflect trophic level nitrogen sources within a food web. In relation to the reconstruction of ancient human diet the contribution of marine and terrestrial protein are strongly reflected in Δ15NGlu-Phe values. 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.
RATIONALEStable nitrogen isotope (δ15N) values of bone collagen are routinely used to inform inte... more RATIONALEStable 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.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.METHODSIn this study we present a methodology for the measurement of amino acid δ15N values using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Amino acid standards of known δ15N values were derivatised to their N-acetylisopropyl (NAIP) esters and purified through Dowex ion-exchange resin to determine any isotopic fractionation associated with derivatisation and ion-exchange chromatography. The effect of starch on AA δ15N values was also determined by hydrolysing bone collagen with and without the presence of starch.In this study we present a methodology for the measurement of amino acid δ15N values using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Amino acid standards of known δ15N values were derivatised to their N-acetylisopropyl (NAIP) esters and purified through Dowex ion-exchange resin to determine any isotopic fractionation associated with derivatisation and ion-exchange chromatography. The effect of starch on AA δ15N values was also determined by hydrolysing bone collagen with and without the presence of starch.RESULTSThe amino acids derivatised to their NAIP esters give values within ±0.8‰ of their δ15N values measured separately by elemental analyser (EA)-IRMS, with a precision of better than 0.8‰. The δ15N values of AAs after Dowex ion-exchange chromatography were within ±0.9‰ of their values prior to ion-exchange chromatography. The AA δ15N values of bone collagen hydrolysed with and without starch were within ±0.8‰.The amino acids derivatised to their NAIP esters give values within ±0.8‰ of their δ15N values measured separately by elemental analyser (EA)-IRMS, with a precision of better than 0.8‰. The δ15N values of AAs after Dowex ion-exchange chromatography were within ±0.9‰ of their values prior to ion-exchange chromatography. The AA δ15N values of bone collagen hydrolysed with and without starch were within ±0.8‰.CONCLUSIONSHydrolysis of lipid-extracted plant material followed by purification of AAs using Dowex ion-exchange resin and derivatisation to their NAIP esters is a suitable protocol for the accurate determination of individual plant and animal AA δ15N values by GC-C-IRMS. Copyright © 2012 John Wiley & Sons, Ltd.Hydrolysis of lipid-extracted plant material followed by purification of AAs using Dowex ion-exchange resin and derivatisation to their NAIP esters is a suitable protocol for the accurate determination of individual plant and animal AA δ15N values by GC-C-IRMS. Copyright © 2012 John Wiley & Sons, Ltd.
Natural abundance d 15 N values of plant tissue amino acids (AAs) reflect the cycling of N into a... more Natural abundance d 15 N values of plant tissue amino acids (AAs) reflect the cycling of N into and within plants, providing an opportunity to better understand environmental and anthropogenic effects on plant metabolism. In this study, the AA d 15 N values of barley (Hordeum vulgare) and bread wheat (Triticum aestivum) grains and rachis and broad bean (Vicia faba) and pea (Pisum sativum) seeds, grown at the experimental farm stations of Rothamsted, UK and Bad Lauchstädt, Germany, were determined by GC-C-IRMS. It was found that the d 15 N values of cereal grain and rachis AAs could be largely attributed to metabolic pathways involved in their biosynthesis and catabolism. The relative 15 N-enrichment of phenylalanine can be attributed to its involvement in the phenylpropanoid pathway and glutamate has a d 15 N value which is an average of the other AAs due to its central role in AA-N cycling. The relative AA d 15 N values of broad bean and pea seeds were very different from one another, providing evidence for differences in the metabolic routing of AAs to the developing seeds in these leguminous plants. This study has shown that AA d 15 N values relate to known AA biosynthetic pathways in plants and thus have the potential to aid understanding of how various external factors, such as source of assimilated N, influence metabolic cycling of N within plants.
Journal of Archaeological Science, 2015
An established method of estimating the trophic level of an organism is through stable isotope an... more An established method of estimating the trophic level of an organism is through stable isotope analysis of its tissues and those of its diet. This method has been used in archaeology to reconstruct past human diet from the stable nitrogen isotope (d 15 N) values of human and herbivore bone collagen. However, this approach, using the 15 N-enrichment of human bone collagen d 15 N values over associated herbivore bone collagen d 15 N values to predict the relative importance of animal protein, relies on the assumptions that: (i) the d 15 N values of plants consumed by humans and herbivores are identical, and (ii) the 15 Nenrichment between diet and consumer is consistent. Bone collagen amino acid d 15 N values have the potential to tackle these uncertainties, as they constrain the factors influencing bone collagen d 15 N values. In this study, the d 15 N values of glutamic acid and phenylalanine in human and herbivore bone collagen isolates from Neolithic sites in Germany, Greece and Turkey were determined by gas chromatography-combustion-isotope ratio mass spectrometry. The fraction of animal protein in total dietary protein consumed by the humans was estimated by: (i) comparing bulk human and herbivore collagen d 15 N values, (ii) comparing bulk human and herbivore collagen and ancient charred cereal grain d 15 N values, (iii) comparing human bone collagen d 15 N Glutamic acid and d 15 N Phenylalanine values, and (iv) comparing d 15 N Glutamic acid values of human and herbivore bone collagen and estimated d 15 N Glutamic acid values of ancient charred cereal grains. Where determined cereal grain d 15 N values are higher than estimated herbivore forage values, estimates of animal protein consumption are significantly lower, emphasising the importance of the plant nitrogen contribution to human bone collagen. This study also highlights the need for further investigation into: (i) the D 15 N Consumer-Diet values of glutamic acid and phenylalanine in terrestrial ecosystems, and (ii) D 15 N Glutamic acid-Phenylalanine values of common plant foods in order to improve the accuracy and more widespread applicability of amino acid-based methods for palaeodietary reconstruction.