Cultivation of Naked Barley by Early Iron Age Agro-pastoralists in Xinjiang,China

ABSTRACT

We report an archaeobotanical analysis of flotation samples taken from Shirenzigou, an Early Iron Age agro-pastoralist site dated between the fourth and first century BC, located on the northern slope of the Tianshan Mountains in Xinjiang, China. The charred macro-botanical assemblage is dominated by naked barley grains with a few broomcorn and foxtail millet grains. In the context of Trans-Eurasian exchange of cereal crops, southwest Asian crops (wheat and barley) and two Asian millets (broomcorn and foxtail) were introduced to Xinjiang a few centuries to a millennium before Shirenzigou was occupied. The choice of barley cultivation in preference to wheat and millet may have been possibly driven by the relatively extreme local environment and the scheduling requirements of mobile pastoralism. Barley is well suited to this environment, and the choice of naked barley in preference to hulled barley may have been driven by the whole grain tradition prevailing in East Asia.     

DNA analysis in charred grains of naked wheat from several archaeological sites in Spain

In the present work we attempt to recover endogenous ancient DNA from cereal grains preserved under different conditions: charred, partially charred and waterlogged. A total of 126 grains from naked wheat and 18 from barley from different sites on the Eastern Iberian Peninsula ranging from the beginning of agriculture in the region to the turn of the Common Era, were studied. Two different extraction protocols were used, a standard phenol–chloroform method and a silica-based DNA extraction procedure implemented for artificially charred seeds. Amplifications were directed to three markers: the large subunit of ribulose 1,5 biphosphate carboxylase (rbcL) and the microsatellite WCT12 in the chloroplast genome and the x and y subunits of the high molecular weight glutenin gene (Glu-1) in the nucleus. The first two were used to assess the preservation status of the samples, while with the third we tried to identify the wheat grains at species level. It was possible to obtain eleven positive amplifications in 8 partially charred seeds but only two amplifications of the Glu-1 gene from a single sample of the Early Bronze age were genome-specific. Different contamination sources were identified and reported. Cloning and alignment of sequenced clones showed a correspondence of the amplified fragment to modern wheat D genome haplotypes. This result suggests that the sample corresponds to hexaploid wheat (Triticum aestivum L.), thus being the first ancient DNA evidence to date for the cultivation of hexaploid wheat in the prehistoric agriculture of the Iberian Peninsula. Moreover, obtained results highlight contamination problems associated to the study of ancient archaeobotanical charred seeds suggest that the combination of a silica-based extraction method together with the amplification of specific targets is a good strategy for recovering endogenous ancient DNA from this kind of material.     

Ancient DNA in archaeological wheat grains: preservation conditions and the study of pre-Hispanic agriculture on the island of Gran Canaria (Spain)

The recovery of ancient DNA from archaeological wheat samples under different preservation conditions was assessed using a number of genetic markers. It was possible to amplify nuclear DNA from desiccated grains but not from charred. The desiccated grain was from a pre-Hispanic grain silo in Gran Canaria and showed excellent DNA preservation, enabling the amplification of the ribosomal DNA markers IGS and ITS, the upstream region of the HMW-glutenin locus and single-locus nuclear microsatellites. Our results demonstrated the presence of both durum and bread wheat in an assemblage of naked grain. We were also able to identify different genotypes in durum wheat and compare these with extant landraces, providing insights into the agrarian practices of the ancient Canarians and the origin of their crops.     

Miliacin in palaeosols from an Early Iron Age in Ukraine reveal in situ cultivation of broomcorn millet

During the archaeobotanical investigation of Scythian–Sarmatian period (Early Iron Age), pits with crop processing waste, discovered in the floodplain of Donets River, eastern Ukraine, and charred remains of cereal grains, dominated by broomcorn millet, were recorded. The grains from the pits were radiocarbon dated to the fifth to first century BC. Those pits are distant from any known contemporaneous settlement. The apparent disconnection of these pits from any local settlement suggests that (1) millet was brought from other locations by mobile groups, or (2) millet was cultivated locally by populations whose settlements have left no discernible archaeological trace. The analysis of molecular biomarkers preserved in palaeosols that are stratigraphically connected to the pits revealed high levels of miliacin, a molecule that can be preserved in ancient soils and sediments, and that is consistent with broomcorn millet (Panicum miliaceum). High levels in miliacin in soils stratigraphically connected to the pits are interpreted as the result of a large biomass of P. miliaceum produced at time of soil formation. Our biogeochemical results applied to a palaeosol thus attest to the in situ cultivation of crops dominated by the broomcorn millet during the early Iron Age in the floodplain of Donets River. Biochemical examination of soils and palaeosols can thus provide useful information on past dynamics of land-use by ancient population, especially when settlements or macrobotanical remains are absent.     

The effect of charring and burial on the biochemical composition of cereal grains: investigating the integrity of archaeological plant material

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 δ¹³C values and a systematic increase of 0.8‰ in the δ¹⁵N 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 in the ancient charred grains was retained in the stable melanoidins whose polymeric structure makes them resistant to subsequent degradation.     

Archaeobotanical investigation of two Scythian-Sarmatian period pits in eastern Ukraine: Implications for floodplain cereal cultivation

Abstract

Two Scythian-Sarmatian period pits dated to the 5th–1st centuries b.c. were discovered while excavating the Chalcolithic site of Zanovskoe, located on a floodplain of the Donets River in the steppe region of eastern Ukraine, Lugansk oblast. No contemporaneous settlement sites are known in the region. Archaeobotanical analysis was conducted on charred plant macrofossils recovered from pits at the site. The crop assemblage consisted of hulled barley and broomcorn millet, from which AMS radiocarbon dates were obtained. Other identified plant species mostly constituted arable weeds and wetland plants. The archaeobotanical assemblage implies floodplain cereal cultivation strategies among the steppe inhabitants during this period.     

Variations in the C/C ratios of modern wheat grain, and implications for interpreting data from Bronze Age Assiros Toumba, Greece

Variations in the ¹³C/¹²C ratios of wheat grain at different spatial and temporal scales are examined by analysis of modern samples, including harvests of einkorn and durum wheat from Greece, and serve as a guide to interpreting data for Bronze Age grains from Assiros Toumba. The normal distribution and low variability of δ¹³C values of einkorn from 24 containers in the Assiros storerooms are consistent with pooling of local harvests, but less likely to represent the harvest of several years or include grain imported from further afield. Correlation between emmer and spelt δ¹³C values provides strong support for other evidence that these were grown together as a maslin crop. ¹³C discrimination (Δ) for the Bronze Age samples is estimated to be 2.5‰ larger than at present, and would be consistent with an intensive, horticultural regime of cereal cultivation, possibly involving some watering.     

山东高青陈庄遗址炭化种子果实研究

通过对山东高青陈庄遗址灰坑等遗迹中出土的炭化植物种子果实进行鉴定和统计分析,探讨了该聚落人类与植物的关系:(1)遗址中出土的丰富的粟、黍和草木犀属植物遗存,可能与马的喂养有关;(2)陈庄聚落西周时期农业是主要的食物来源,农作物包括了文献记载的"五谷",就是粟、黍、小麦、大豆和稻,粟和小麦等旱地作物占的比重最高,水稻可能较少,牛筋草等杂草可能是收获等过程中带入聚落内的;(3)常见的野生植物如野大豆、枣、葡萄以及动物遗骸等可能反映狩猎捕捞仍然作为食物的补充。     

DNA in cremated bones from an early bronze age cemetery cairn

The discovery of polymeric DNA in charred wheat grains and other burnt plant remains prompted us to examine a set of cremated bones for the presence of ancient DNA. Extracts of cremated bones from an early Bronze Age cemetery cairn were analysed by hybridization probing and the polymerase chain reaction. Hybridization with two probes targeting human DNA resulted in strong positive signals. Polymerase chain reactions directed at a multicopy sequence in human nuclear DNA were successful, extracts of five burials giving amplification products of the expected size. Exploitation of ancient DNA in cremated bones could be of great value in archaeology as it may enable information pertaining to sex and kinship to be obtained from fragmented material.     

Molecular markers for the discrimination of Triticum turgidum L. subsp. dicoccum (Schrank ex Schübl.) Thell. and Triticum timopheevii (Zhuk.) Zhuk. subsp. timopheevii

The persistent uncertainty on the classification of the “new” glume wheat found in Neolithic and Bronze Age sites from Greece and other European settlements might be resolved only through analysis of its ancient DNA. Tools able to discriminate among different Triticum species on the basis of scarce, very damaged DNA, are therefore essential. While current attempts concentrate on DNA fragments sequencing and comparison, in some instances PCR-based selective amplification techniques might offer a cheaper and quicker alternative. The purpose of this research was therefore the identification of species-specific primers, able to distinguish caryopses of Triticum timopheevii subsp. timopheevii from those of Triticum turgidum subsp. dicoccum. Primers and their working conditions were defined and optimized using DNA from modern accessions. The ribosomal primers ITS1 tim and ITS2 tim, and the nuclear primer acetyl-coenzyme A tim clearly discriminated the sequences of Triticum timopheevii from other species. Finally, Neolithic charred wheat grains found in the sites of Sammardenchia (Pozzuolo del Friuli, Udine) and La Marmotta (Lago di Bracciano, Roma), belonging to the “new” wheat type or to emmer, were tested with the three selected primers. However, the results were not conclusive, because the samples analysed were apparently too degraded to yield useful DNA.     

Book Reviews

Abstract

Plant macroremains were recovered during the renewed excavation at Grap?eva ?pilja, a cave on the island of Hvar in Croatia. This is the first archaeoboatnical investigation on an eastern Adriatic island to use flotation samples. Samples were taken from layers dating from the Early Neolithic to the Middle Bronze Age (ca. 6000–1500 B.C.). Sixteen radiocarbon dates obtained from wood charcoal date the samples precisely. Detailed archaeobotanical analyses of plant macroremains reveal plant use during the occupation of the cave, with the highest density of plant remains in the Neolithic. Oak acorns were the most abundant plant remains. Finds of two types of juniper berry cones, various parts of gymnosperm cones, and cypress seeds and leaves indicate that the Mediterranean evergreen woodland was exploited. Remains of cultivated plants are rare. A small number of cereal grains, including emmer, einkorn, and possibly bread wheat were recovered from the Neolithic layers, as well as a few wheat grains from later horizons. Remains of typical wild Mediterranean fruits included almond nutshell fragments, a grape pip, and a fig seed. These finds indicate that the occupants of Grap?eva utilized processed crops but also gathered plants from the wild for food, fuel, and perhaps ritual. Fourier Transform Infrared Spectroscopy (FTIR) analysis was performed in order to assess charred versus mineralized preservation. Macroplant remains from Grap?eva were compared to the few available plant analyses from the eastern Adriatic. This comparison provides evidence that caves had different functions both from each other and from open-air sites. The plant remains are discussed in the context of the spread of farming on both sides of the Adriatic.     

Impact of charring on cereal grain characteristics: linking prehistoric manuring practice to δN signatures in archaeobotanical material

Systematic use of animal manure has been demonstrated to be detectable in the plant δ¹⁵N value but evidence of manure affecting isotopic composition is mainly based on studies of fresh plant material. These findings can potentially be applied to archaeobotanical assemblages and thus provide information about prehistoric manuring practice. Prehistoric grains are generally found in a charred state of which the exact charring conditions are unknown but most likely often multifarious. In this study we examined the influence of grain weight and a range of charring conditions with regards duration, temperature, oxygen availability, and manuring. The charring was applied to emmer, spelt and naked barley with assessment of weight loss, N concentration and δ¹⁵N. There were only small and non-systematic variations in δ¹⁵N in relation to grain weight class. We also found that charring did not distort δ¹⁵N in either a systematic or substantial way and conclude that manuring most likely will be detectable in archaeobotanical charred grains. As certain within-grain variability in δ¹⁵N existed, especially in the intensively manured grains, the resolution of this kind of information should be carefully considered. However, despite attempts to deliberately tamper and distort the grain δ¹⁵N signature, the changes observed in this study were too small to be of any consequences for the archaeobotanical applicability of the method. Thus the isotope method offers unique evidence about prehistoric manuring practice.     

Improved methodology for extraction and amplification of DNA from single grains of charred wheat

Comparisons were made between two commonly used methods for the extraction of ancient DNA from charred plant remains. Using artificially charred wheat seeds, we show that silica-binding is the most efficient method for extraction of DNA. We describe a improved silica-binding procedure, including pre-incubation with N-phenacylthiazolium bromide and increased washing of bound DNA, which yields amplifiable DNA from seeds heated at 200 °C for up to 8 h, conditions which promote the formation of Maillard products which often copurify with aDNA and inhibit subsequent PCRs. We believe that this method will be effective in ancient DNA extraction with most types of charred archaeobotanical material. Both cold- and hot-start PCR procedures gave good amplicon yields with extracts prepared in this way, but cold-start PCRs also resulted in synthesis of short artefact products. Addition of bovine serum albumin to PCRs, an inert carrier substance thought to enhance amplification efficiency by binding contaminants, had no advantageous effect and in fact reduced amplicon synthesis.     

Distribution patterns of cultivated plants in the Eastern Alps (Central Europe) during Iron Age

Carbonized fruits and seeds from two recently investigated Iron Age hilltop settlements, one located north and the other south of the main Alpine range, were analyzed and reveal a detailed insight in the subsistence strategies of the Eastern Alps. The results were compared with archaeobotanical data sets from other Iron Age excavation sites in Austria, Eastern Switzerland and Northern Italy. On the basis of variable data from 17 sites it is not possible to detect a geographical pattern through statistical analyses. On the basis of the frequencies, however, it becomes clear that the principal cereals were Hordeum vulgare (hulled six-rowed barley), Triticum dicoccon and T. spelta (emmer and spelt) and Panicum miliaceum (broomcorn millet). In addition, foxtail millet (Setaria italica) as well as naked wheat played some role. Legumes such as Vicia faba (horse bean) and Pisum sativum (pea) also occurred regularly and supplemented the diet of the prehistoric settlers. More systematic research with standardized methods is however urgently needed to corroborate the existing data.     

The oldest agriculture in northern Atlantic Spain: new evidence from El Mirón Cave (Ramales de la Victoria,Cantabria)

Emmer wheat (Triticum diccocum) has been positively identified from the stratigraphically oldest ceramic- and domesticated livestock-bearing level of El Mirón Cave in the Cantabrian Cordillera. The grain is AMS ¹⁴C-dated to 5550±40 BP. This date is congruent with six others from the same layer, higher within which were found other grains of wheat, including einkorn as well as emmer. Although wild ungulates (mainly red deer) were still hunted, abundant ovicaprines, together with small numbers of cattle and pigs, appear in this level-for the first time in the 40,000-year record at El Mirón. Potsherds (undecorated, but of very good quality) also appear abruptly and abundantly. However, the associated lithic assemblage contains specific tool types also found in late Mesolithic contexts in Cantabrian Spain. In addition to the full suite of Neolithic indicators at El Mirón, as confirmed by less unambiguous early agro-pastoral evidence from other sites in the Vasco-Cantabrian region, there are megalithic monuments both in the vicinity of the cave and throughout the region that are similarly dated. All these data tend to suggest that Neolithic adaptations—already present about a millennium earlier not only along the Mediterranean coast, but also much closer, to the southeast of the Cordillera—were quickly adopted as “a package” by Cantabrian Mesolithic foragers, possibly as a consequence of social contacts with Neolithic groups in southern France and/or the upper Ebro basin of north-central Spain.     

Ancient DNA analysis of desiccated wheat grains excavated from a Bronze Age cemetery in Xinjiang

Wheat has been one of the most important crop in Eurasia since the Neolithic period. Understanding the spread of wheat cultivation is crucial to understanding the spread of agriculture as a whole and the interactions between prehistoric populations across the Eurasian continent. However, the routes by which wheat cultivation spread eastwards have been poorly understood to date, due to the scarcity of plant remains recovered from archaeological sites. Desiccated wheat grains excavated from the Xiaohe cemetery in Xinjiang, and dated to the early Bronze Age, show excellent DNA preservation. Here we present an ancient DNA (aDNA) analysis of wheat (Triticum sp.) grains excavated from Xiaohe and provide the first definitive evidence for bread wheat in China during the Bronze Age. The nuclear ribosomal DNA internal transcribed spacer regions (ITS1 and ITS2) and the intergenic spacer region (IGS) were amplified. The IGS region within the D genome of wheat has a 71 bp insertion that is absent from corresponding regions in the A and B genomes. The results showed that the Xiaohe wheat showed most sequence similarity to hexaploid bread wheat (Triticum aestivum), including the characteristic insertion into the D genome. The presence of bread wheat at the Xiaohe cemetery is discussed in relation to it having spread into Xinjiang by the Bronze Age, providing new insight into the origins of bread wheat in East Asia.     

From the modern to the archaeological: starch grains from millets and their wild relatives in China

Starch grains from 31 modern samples of millets derived from the seeds of 7 species within the genus Setaria and 2 species within the genus Panicum were analyzed to determine diagnostic morphological characteristics. Ancient starch grains recovered from a sample of broomcorn millet (Panicum miliaceum) excavated from the Cishan site (10.0-7.6 cal yr BP) in the North China Plain were then subjected to the same analyses to determine the differences in morphologies, if any, between modern and ancient samples. The data indicate that morphological features, and particularly surface and fissure features, will allow for solid identifications of ancient millet starches, while size classes will be helpful, but will not be dependable taxonomic indicators.     

Neolithic and Bronze Age Agriculture in Southern Scandinavia – Recent Archaeobotanical Evidence from Denmark

Abstract

This paper presents archaeobotanical studies from the Danish regions of Thy, northern Schleswig and Djursland. The data are discussed in the light of developments in the landscape and in house architecture; comparisons are made with the contemporary situation in southern Sweden. Pollen analysis reveals that Thy was more or less treeless by the end of the Neolithic, whereas Djursland maintained its forests for a further 1500 years; the situation in northern Schleswig lies somewhere in between. Developments in house architecture are very similar in the three areas. The shift from two-aisled to three-aisled houses occurred in period I/II of the Bronze Age and phosphate analyses suggest that the earliest Danish byre dates from the beginning of period II.

Crop plant assemblages are dominated by naked barley and emmer and remain remarkably stable from the Single Grave Culture to the Late Bronze Age in Thy, from the Middle Neolithic to the middle of the Bronze Age in northern Schleswig, and from the Late Neolithic to the Late Bronze Age on Djursland. Other crops come and go – einkorn, bread wheat, spelt, millet, flax, oats and gold of pleasure. Hulled barley is largely conspicuous by its absence. Well-developed arable weed floras appear first in the Early Bronze Age – arable weeds are very scarce at Neolithic sites. There is evidence of improvement of arable soils using fen peat and household refuse and manure. The situation appears somewhat more complex in Denmark than that described for Sweden. The most striking difference is seen in the behaviour of hulled barley, which becomes massively dominant in Sweden in the course of the Bronze Age, whereas its role in Denmark is much more modest.     

Archaeological and Historical Materials as a Means to Explore Finnish Crop History

ABSTRACT

In Northern Europe, barley (Hordeum vulgare L.) has been cultivated for almost 6000 years. Thus far, 150-year-old grains from historical collections have been used to investigate the distribution of barley diversity and how the species has spread across the region. Genetic studies of archaeobotanical material from agrarian sites could potentially clarify earlier migration patterns and cast further light on the origin of barley landraces. In this study, we aimed to evaluate different archaeological and historical materials with respect to DNA content, and to explore connections between Late Iron Age and medieval barley populations and historical samples of barley landraces in north-west Europe. The material analysed consisted of archaeological samples of charred barley grains from four sites in southern Finland, and historical material, with 33 samples obtained from two herbaria and the seed collections of the Swedish museum of cultural history.

The DNA concentrations obtained from charred archaeological barley remains were too low for successful KASP genotyping confirming previously reported difficulties in obtaining aDNA from charred remains. Historical samples from herbaria and seed collection confirmed previously shown strong genetic differentiation between two-row and six-row barley. Six-row barley accessions from northern and southern Finland tended to cluster apart, while no geographical structuring was observed among two-row barley. Genotyping of functional markers revealed that the majority of barley cultivated in Finland in the late nineteenth and early twentieth century was late-flowering under increasing day-length, supporting previous findings from northern European barley.     

关于夏商周文明形成时期农业经济特点的一些思考

黄河流域地区是粟和黍的起源地, 也是夏商周文明的诞生地, 由此导致了夏商周文明的农业基础应该是以粟和黍为主要粮食作物的传统认识, 但事实是否如此是一个值得认真讨论的问题。结合甲骨文的记载, 并通过对该地区自然生态环境背景、农作物的生长习性以及现有的考古资料的综合分析, 本文认为, 黄河流域地区农业经济的发展在夏商周时期出现了新的变化, 粟和黍的主导地位开始受到冲击, 麦类作物已经传入, 稻谷在夏商周文明形成过程中发挥了重要的作用。