Crop water availability in early agriculture: evidence from carbon isotope discrimination of seeds from a tenth millennium BP site on the Euphrates

The analysis of carbon isotope discrimination (Δ) in crop plant remains from archaeological sites may help to assess water availability for early agriculture. This study presents the analysis of Δ in seeds of naked wheat (Triticum aestivum/durum), lentil (Lens orientalis/culinaris), and flax (Linum sp.) found at the archaeological site of Tell Halula in the valley of the Middle Euphrates (Syria). This Neolithic site is the oldest in this region of the Fertile Crescent where the cultivation of domesticated plants has been reported, with seed remains ranging from 9550 to 8465 BP. Most of the seeds analysed showed Δ values greater than 16 ‰, reaching 20 ‰ for some samples of flax. For wheat, Δ values were much higher than those reported in present-day (1996) durum wheat crops cultivated under rainfed conditions in north-west Syria under environments with somewhat higher rainfall than Tell Halula. Similarly, grains of present-day (1997) barley cultivated in the archaeological site also showed lower values than those found in archaeological kernels. An empirical relationship between Δ of mature kernels and total precipitation (plus irrigation where applicable) from heading to maturity (r² = 0.82, n = 11) was established for durum wheat, currently cultivated in different environments of the Mediterranean basin. The resulting relationship was applied to the data on Δ of wheat fossil kernels from Tell Halula to estimate the accumulated water inputs during the time (about 6 weeks) the kernels were produced. Calculated water inputs for wheat during early agriculture were (over 110 mm) at least 5 times higher than current-day rainfall accumulated in Tell Halula during the same phenological period. These results strongly suggest that early agriculture wheat was cultivated at Tell Halula under much wetter conditions than are currently to be found in the area. The presence of flax and its very high Δ values also support this conclusion. Whether such humid conditions during cultivation were due to moister conditions prevailing at this time, by planting in alluvial areas or by irrigation works is discussed.     

Continuity and changes in plant resources during the Neolithic period in western Switzerland

The Neolithic and Bronze Age (4400-1570 B.C.) pile dwellings of Concise-sous-Colachoz on the shore of Lake Neuchatel (Canton of Vaud, western Switzerland), known as an archaeological site for more than 140 years, were recently re-investigated due to rescue excavations. Plant macrofossil analyses were done for several Neolithic occupation phases (3868-2440 B.C. the Cortaillod classique, Cortaillod moyen, Cortaillod tardif and Auvernier periods) with a focus on cereal remains, and additionally, archaeological deposits dating to the Cortaillod moyen culture (3710-3677 B.C.) were studied in detail. The preliminary study of cereal macrofossil remains from all the mentioned Neolithic phases show that the most important cereals were Triticum aestivum/durum/turgidum (naked wheat), T. monococcum (einkorn) and Hordeum vulgare (barley). The preferences for specific crops did obviously not alter significantly through time, but, extraordinarily, significant amounts of einkorn continued to be grown for at least 1400 years during the Neolithic period. Other cultivated plants were Pisum sativum (pea), Linum usitatissimum (flax), and Papaver somniferum (opium poppy). Additionally to the seeds, capsule fragments of opium poppy were found in the Cortaillod moyen deposits. These represent the first finds of uncharred capsule fragments in Europe. Compared with other central European sites, opium poppy was very common during the 38th and 37th cent. B.C. and obviously less appreciated towards the end of the Neolithic in the western part of Switzerland. In central Switzerland the trends seem different: there opium poppy was mainly used during the Late Neolithic period. This may be due to cultural differences within contemporaneous human societies. Wild fruits which were collected as plant resources during the Cortaillod moyen period included Prunus spinosa (sloe), Cornus sanguinea (dogwood), Malus sylvestris (apple), Rubus idaeus/caesius/fruticosus (raspberry/dewberry/blackberry), Fragaria vesca (wild strawberry), Rosa sp. (hip), Quercus sp. (acorn), Corylus avellana (hazelnut), and Fagus sylvatica (beechnut), among others. Compared with other Neolithic sites in westem and central Switzerland the local population of Concise-sous-Colachoz used few sloes, while dogwood fruits were in use throughout the Neolithic period at Lake Neuchatel. Received September 4, 2001 / Accepted May 13, 2002     

西北不同降水区域新石器至青铜时代人类活动与环境变化的关系

中国西北地区史前人类活动与生存环境变化的关系是学术界关注的热点科学问题。本文通过总结分析西北地区新石器至青铜时代遗址¹⁴C测年、动植物遗存以及人骨碳同位素数据,梳理了不同降水量区域人与环境相互作用的时空特征和变化过程,以及可能的影响因素。研究结果表明,10000-6000 BP,人类活动强度较弱且多分布在降水量大于400 mm的区域,人类活动与气候的关系尚不清楚;6000-4000 BP,粟黍农业的强化促进了人类活动空间向西扩散,显著的气候事件导致人类活动强度下降,人类活动对自然环境的影响开始显现;4000-2200 BP,史前跨大陆文化交流带来的农牧业元素促使不同降水量区域生存资料多样化,人类适应和影响环境的能力进一步加强,但该时期人类活动强度存在时空差异性,对环境的影响仅在区域尺度上呈现。     

Water management practices and climate in ancient agriculture: inferences from the stable isotope composition of archaeobotanical remains

Carbon isotope discrimination (Δ¹³C) in charred grains from archaeological sites provides reliable information about water availability of ancient crops. However, as cereals are cultivated plants, they may reflect not only climatic fluctuations, but also the effect on water status of certain agronomic practices, such as sowing in naturally wet soils or irrigation. In this work, we propose a methodological approach to combine Δ¹³C data from different plant species, in order to discriminate between climate-derived and anthropogenic effects on ancient crops. We updated previous models for estimating water inputs from Δ¹³C of cereal grains of Hordeum vulgare and Triticum aestivum/durum, and we applied them to published data from several archaeological sites, including samples from the Neolithic to the present day in northeast and southeast Spain, as well as from the Neolithic site of Tell Halula (northwest Syria). We found an important decrease in water availability from the Neolithic to the present time in the three areas of study, especially clear for the two driest areas (southeast Spain and northwest Syria). Potential differences in water management practices between wheat and barley, as well as between cereal and legume crops (Vicia faba and Lens culinaris), are also discussed on the basis of the comparison of Δ¹³C values across several archaeological sites.     

Pollen and phytolith evidence for rice cultivation during the Neolithic at Longqiuzhuang, eastern Jianghuai, China

Phytolith and pollen analyses were carried out at the archaeological site at Longqiuzhuang in Gaoyou, Jiangsu, southern China. The results indicate that the key morphological phytolith types associated with cultivated rice (Oryza) are common in the Neolithic cultural layers at this site. The evidence strongly suggests that cultivated rice (mainlyO. japonica) was grown locally during the Neolithic. The archaeopalynological record provides information about the impact of human activity and, in particular, farming on the natural vegetation. The evergreen and deciduous broad-leaved forest was substantially altered, and herbaceous taxa, including ruderals, expanded. Based on the results from the phytolith and pollen analyses, two distinct phases of human activity have been recognized, namely (1) phase A (7000-6300 B.P., i.e. early Neolithic) a warm and humid period when arable farming, including rice cultivation, was pursued but the variation in the size of the carbonized rice grains was low, and (2) phase B (6300-5500 B.P., late Neolithic age), a period of relatively cold and/or arid climate when cultivated rice was of major importance and was morphologically similar to present-day rice. Environment, and in particular climate change in the late Neolithic, were important factors affecting the development of rice as a cultivated crop. It was mainly during this period that artificial selection favoured the emergence of forms similar to those of today.     

Évolution de l’exploitation des ressources animales dans la région cantabrique entre 4500 et 2000 cal BC : la grotte de Los Gitanos (Cantabrie,Espagne)

The archaeozoological remains found in the four Neolithic and Chalcolithic sub-levels at the archaeological site of Los Gitanos Cave are analysed. Continuity is seen in the exploitation of the marine environment, while the percentage of domestic ungulates, in comparison with hunted animals, progressively increases. Finally, the site is contextualised in an overview of the use of animal resources in Cantabrian Spain from the fifth to the third millennia.     

Neolithic cultivated plants from Albania

Macroremains of late Neolithic cultivated plants are reported from the archaeological site of Maliq, Korça District, south-eastern Albania. The material comprises einkorn (Triticum monococcum L.), emmer (Triticum dicoccon Schrank), barley (Hordeum vulgare L.), lentil (Lens culinaris Medik.) and bitter vetch (Vicia ervilia (L.) Willd.). These are the first remains of cultivated plants described from an archaeological site in Albania.     

Modelling Mediterranean oak palaeolandscapes using the MaxEnt model algorithm: The case of the NE Iberia under the Middle Holocene climatic scenario

The Mediterranean Basin is a global biodiversity hotspot, and oak tree species play an important role in it. Since the beginning of the Holocene (∼11.4 kyr BP), the distribution of forests has not occurred uniformly, resulting in diverse types of vegetation landscapes. In this study, we used a maximum entropy algorithm (MaxEnt) to obtain the ecological niche model (ENM) of two sub-Mediterranean oak species, Quercus pubescens Willd. (pubescent oak) and Quercus ilex subsp. ilex (holm oak), both in the present day in the Iberian Peninsula and within a Middle Holocene (8.2–4.2 kyr BP) climatic scenario in the NE Iberian Peninsula. Moreover, we used the locations of Neolithic archaeological sites containing anthracological data to analyze the relationship between human occupations and oak habitats. Our results suggest that the two oaks have responded differently to the climatic conditions that have occurred, and show changes in both potential distributions. The palaeolandscape vegetation map shows a denser vegetation cover in the lowlands and a more open landscape in the highlands, with a higher dominance of Quercus pubescens in the septentrional areas, while Quercus ilex was more restricted to certain coastal areas. Temperature and precipitation factors, mainly seasonal climatic conditions, have had a greater impact on the distribution of vegetation than other factors. We found a good overlap between the ENM of the two oaks and the locations of the Neolithic sites analysed, and determined that the distribution of Neolithic archaeological sites is not random. The Neolithic populations in the study area depended heavily on the resources of the deciduous and evergreen sub- Mediterranean forest, although they also exploited the resources of the mountain pine forest. Neolithic sites distribution suggests that Neolithic human groups were aware of the potential of forests and probably gathered woody resources in their surroundings.     

Agriculture and food from the Roman to the Islamic Period in the North-East of the Iberian peninsula: archaeobotanical studies in the city of Lleida (Catalonia, Spain)

The urban archaeological excavations carried out in the city of Lleida (Catalonia, Spain) have opened the way for an interdisciplinary project on the ancient landscape, agriculture and food. Here we present the results of the archaeobotanical study of seeds and fruits from this project, centred on the Roman and Islamic periods of the city, between the 2nd century B.C. and the 11th century A.D. During the whole of this period the cultivation and consumption of cereals was found. The most important cereals were hulled barley and naked wheat. This was already known from the later prehistoric era in the area and is similar to findings at other sites from the same period in the western Mediterranean. These cereals are accompanied by some leguminous crops and the presence of grapes and figs is very significant. The expansion of vine cultivation, together with a certain amount of tree growing was one of the basic contributions of the Roman world to proto-historical (Bronze- and Iron Age) agriculture in western Catalonia, as in other parts of Europe. In the Islamic period, there seems to have been an increase in the number of fruit tree species; however for taphonomical reasons this has to be confirmed by future investigations. Flax, already known in prehistoric times, and Gold-of-pleasure must be added to the finds. Also since the Roman period some other taxa, such as celery or fennel, might have been grown. During the time period considered in this paper, there was a wide range of plants grown and consumed. This clearly contrasts with everything known about earlier periods in western Catalonia, during which the only cultivated plants were cereals and flax.     

Archaeobotanical remains of hulled and naked cereals in the Iberian Peninsula

Archaeobotanical finds in Spain show differences in the representation of the different wheats and barleys. From the beginning of agriculture (around 5000 B.C.) onwards, all wheats and barleys can be found at the sites of the eastern Peninsula. But in later periods of the early Neolithic, free-threshing wheat becomes more important in the northeast and the southeast, compared to the hulled wheats (emmer and einkorn). Nevertheless, both naked and hulled barleys can be found in similar frequencies in this period. Seed analyses in the southeast and the east of Spain show the importance of naked barley compared with hulled barley in the third millenium uncal B.C. This is not the case in the northeast, where hulled barley has a similar frequency in this period until the Iron Age, when both hulled barley and free-threshing wheat are the most important taxa. The substitution of naked barley for hulled barley in the south-east Iberian Peninsula is very significant in the period of greatest growth of the Argar culture. Free-threshing wheat can be found at a similar frequency throughout the study area, and was an important human food source together with the barleys. Hulled wheats seem to have played a secondary role as food in all periods, although they are constantly present in our samples. Nevertheless spelt wheat does not appear until the Roman period, when it is only found on the Cantabrian north coast, where it is important.     

Mitochondrial DNA from El Mirador Cave (Atapuerca,Spain) Reveals the Heterogeneity of Chalcolithic Populations

Previous mitochondrial DNA analyses on ancient European remains have suggested that the current distribution of haplogroup H was modeled by the expansion of the Bell Beaker culture (ca 4,500–4,050 years BP) out of Iberia during the Chalcolithic period. However, little is known on the genetic composition of contemporaneous Iberian populations that do not carry the archaeological tool kit defining this culture. Here we have retrieved mitochondrial DNA (mtDNA) sequences from 19 individuals from a Chalcolithic sample from El Mirador cave in Spain, dated to 4,760–4,200 years BP and we have analyzed the haplogroup composition in the context of modern and ancient populations. Regarding extant African, Asian and European populations, El Mirador shows affinities with Near Eastern groups. In different analyses with other ancient samples, El Mirador clusters with Middle and Late Neolithic populations from Germany, belonging to the Rössen, the Salzmünde and the Baalberge archaeological cultures but not with contemporaneous Bell Beakers. Our analyses support the existence of a common genetic signal between Western and Central Europe during the Middle and Late Neolithic and points to a heterogeneous genetic landscape among Chalcolithic groups.     

Climatic and cultural changes in the west Congo Basin forests over the past 5000 years

Central Africa includes the world''s second largest rainforest block. The ecology of the region remains poorly understood, as does its vegetation and archaeological history. However, over the past 20 years, multidisciplinary scientific programmes have enhanced knowledge of old human presence and palaeoenvironments in the forestry block of Central Africa. This first regional synthesis documents significant cultural changes over the past five millennia and describes how they are linked to climate. It is now well documented that climatic conditions in the African tropics underwent significant changes throughout this period and here we demonstrate that corresponding shifts in human demography have had a strong influence on the forests. The most influential event was the decline of the strong African monsoon in the Late Holocene, resulting in serious disturbance of the forest block around 3500 BP. During the same period, populations from the north settled in the forest zone; they mastered new technologies such as pottery and fabrication of polished stone tools, and seem to have practised agriculture. The opening up of forests from 2500 BP favoured the arrival of metallurgist populations that impacted the forest. During this long period (2500–1400 BP), a remarkable increase of archaeological sites is an indication of a demographic explosion of metallurgist populations. Paradoxically, we have found evidence of pearl millet (Pennisetum glaucum) cultivation in the forest around 2200 BP, implying a more arid context. While Early Iron Age sites (prior to 1400 BP) and recent pre-colonial sites (two to eight centuries BP) are abundant, the period between 1600 and 1000 BP is characterized by a sharp decrease in human settlements, with a population crash between 1300 and 1000 BP over a large part of Central Africa. It is only in the eleventh century that new populations of metallurgists settled into the forest block. In this paper, we analyse the spatial and temporal distribution of 328 archaeological sites that have been reliably radiocarbon dated. The results allow us to piece together changes in the relationships between human populations and the environments in which they lived. On this basis, we discuss interactions between humans, climate and vegetation during the past five millennia and the implications of the absence of people from the landscape over three centuries. We go on to discuss modern vegetation patterns and African forest conservation in the light of these events.     

Palaeogenetic evidence supports a dual model of Neolithic spreading into Europe

The peopling of Europe is a complex process. One of the most dramatic demographic events, the Neolithic agricultural revolution, took place in the Near East roughly 10000 years ago and then spread through the European continent. Nevertheless, the nature of this process (either cultural or demographic) is still a matter of debate among scientists. We have retrieved HVRI mitochondrial DNA sequences from 11 Neolithic remains from Granollers (Catalonia, northeast Spain) dated to 5500 years BP. We followed the proposed authenticity criteria, and we were also able, for the first time, to track down the pre-laboratory-derived contaminant sequences and consequently eliminate them from the generated cloning dataset. Phylogeographic analysis shows that the haplogroup composition of the Neolithic population is very similar to that found in modern populations from the Iberian Peninsula, suggesting a long-time genetic continuity, at least since Neolithic times. This result contrasts with that recently found in a Neolithic population from Central Europe and, therefore, raises new questions on the heterogeneity of the Neolithic dispersals into Europe. We propose here a dual model of Neolithic spread: acculturation in Central Europe and demic diffusion in southern Europe.     

Cultivation with deliberation: cereals and their growing conditions in prehistory

The subject of this study is the evaluation of the relationship between cereals grown in prehistory (ca. 5500 bc–ad 600) and environmental conditions during their cultivation on the land that is now the Czech Republic. Charred cereal macroremains were taken from 84 archaeological sites. The representation of species at individual sites was assessed with regard to site altitude, average temperature, precipitation, length of the growing season, soil types and soil productivity within a 1 km buffer zone around each archaeological site. The suitability of using present day environmental data to describe past environmental differences among archaeological sites was verified by expressing environmental conditions using Ellenberg indication values of macroremains of wild taxa. The results of the cereals-environmental conditions analysis show that the most important factor for the crop choice was the period of time of its cultivation. After eliminating the effect of time and length of the growing season, soil quality and altitude become conclusive variables, however with different importance in various periods. The main differences between the macroremain assemblages are represented by the varying proportions of cultivated wheats and barley. In the Neolithic (Proto–Eneolithic) there was no observable effect of environmental factors on the cereal composition. In the Middle Eneolithic–Middle Bronze Age soil type was the main factor in the selection of barley or emmer. In the Late Bronze–Early Iron Ages precipitation, altitude and Chernozems were the decisive factors influencing cereal cultivation while in the Late Iron Age–Migration Period heat load index, precipitation, and the proportion of Fluvisols were the primary determinants. It seems that prehistoric cereal varieties had ecological needs similar to present-day species and the selection of crops took place with respect to local conditions and an effort to achieve an optimum yield.     

Holocene climatic changes in the Western Mediterranean, from south-east France to south-east Spain

Holocene climatic changes along coastal regions from south-east France to south-east Spain were studied using pollen ratios. Comparing modern pollen rain, vegetation and climate along selected transects from the Atlantic Ocean to the Mediterranean, we obtained threshold values of two different ratios corresponding to the different climatic conditions along the transects. These pollen ratios and threshold values were employed to characterize the Holocene climatic changes from nine Mediterranean coastal sites. The results were compared with data from marine and continental pollen sequences distributed in the western Mediterranean basin, and with additional regional data independent of human activity: lake-level fluctuations, alpine glacier advance and retreat chronology, ¹⁴C anomaly and cooling phases in Eastern France and Central Europe. The role of anthropogenic activities and climate on the changes in vegetation is discussed. Six major changes in vegetation cover were identified. They correspond to aridification phases that occurred around 9500–9000 yr BP (10 900–9700 cal BP), 7500–7000 yr BP (8400–7600 cal BP), 4500–4000 yr BP (5300–4200 cal BP), 3700–3300 yr BP (4300–3400 cal BP), 2600–1900 yr BP (2850–1730 cal BP) and 1300–1000 yr BP (1300–750 cal BP). These arid episodes were regional responses to more global climatic changes and determined the changes in the vegetation cover. Humans undoubtedly enhanced the vegetation changes, but none the less had to adapt to these new climatic conditions.     

Effect of leaf structure and water status on carbon isotope discrimination in field-grown durum wheat

The relationships between leaf and kernel carbon isotope discriminations (Δ) and several leaf structural parameters that are indicators of photosynthetic capacity were studied in durum wheat grown in the field under three water regimens. A set of 144 genotypes were cultivated in two rain-fed trials, and 125 of these were grown under supplementary irrigation before heading. Total chlorophyll and nitrogen (N) contents, the dry mass per unit leaf area (LDM, the reciprocal of specific leaf area) and carbon isotope discrimination (Δ) were measured in penultimate leaves and Δ of mature kernels was also analysed. Both LDM and N per unit area showed significant (P≤ 0.001) negative correlation (r=–0.60 and r=–0.36, respectively) with leaf Δ in the wettest trial. Little or no correlation was found for any structural parameter and leaf Δ in the rain-fed trials. In contrast, in the two rain-fed trials LDM was the parameter with the strongest positive correlation (P≤ 0.001) with kernel Δ (r= 0.47 and 0.30) and grain yield (r= 0.43 and 0.29), whereas no correlation was found in the irrigation trial. These correlations, rather than representing a causal link between the amount of photosynthetic tissue and Δ, were probably indirect associations caused by a parallel effect of water status and phenology on leaf structure, grain Δ and yield. Correlations across trials (i.e. environments) between leaf structure and either Δ and yield were very high, although also spurious. Our results suggest that LDM should be used to cull segregating population differences in leaf Δ based on the internal photosynthetic capacity only in the absence of drought. Selecting for kernel Δ and grain yield on the basis of LDM is worthwhile for rain-fed trials.     

Quantifying relationships between rooting traits and water uptake under drought in Mediterranean barley and durum wheat

In Mediterranean regions drought is the major factor limiting spring barley and durum wheat grain yields. This study aimed to compare spring barley and durum wheat root and shoot responses to drought and quantify relationships between root traits and water uptake under terminal drought.One spring barley（Hordeum vulgare L. cv. Rum） and two durum wheat Mediterranean cultivars（Triticum turgidum L. var durum cvs Hourani and Karim） were examined in soil‐column experiments under well watered and drought conditions. Root system architecture traits, water uptake, and plant growth were measured. Barley aerial biomass and grain yields were higher than for durum wheat cultivars in well watered conditions. Drought decreased grain yield more for barley（47%） than durum wheat（30%, Hourani）. Root‐to‐shoot dry matter ratio increased for durum wheat under drought but not for barley, and root weight increased for wheat in response todrought but decreased for barley. The critical root length density（RLD） and root volume density（RVD） for 90% available water capture for wheat were similar to（cv. Hourani） or lower than（cv. Karim） for barley depending on wheat cultivar. For both species, RVD accounted for a slightly higher proportion of phenotypic variation in water uptake under drought than RLD.     

Europe, the bull and the Minotaur: the biological legacy of a Neolithic love story

The European cattle was domesticated 10 000 years ago in eastern Turkey, 1000 years later pottery-associated milk fats identify cattle-based dairy activity in western Turkey. Subsequently, the Indo-European language, domesticated animals and plants travel as a Neolithic package along two major routes across Europe. A striking south-east to north-west gradient of a mutation in the current European population (lactase persistence into adulthood) documents the expansion of a Neolithic dairy culture into a Mesolithic hunter society. Using oral tradition (myths), archaeological and written historical evidence and biological data, it is asked whether highly transmissible viral diseases like measles and smallpox entered during the Neolithic from domesticated animals into the human population. The bovine origin of paramyxovirus infections is likely; smallpox comes from camels or from rodents via cattle while mycobacteria and Helicobacter infected humans already before the Neolithic. Microbes adapt constantly and quickly to changing ecological situations. The current global environmental changes will lead to another highly dynamic phase of viral transmissions into the human population.     

Tracing the genetic origin of Europe's first farmers reveals insights into their social organization

Farming was established in Central Europe by the Linearbandkeramik culture (LBK), a well-investigated archaeological horizon, which emerged in the Carpathian Basin, in today''s Hungary. However, the genetic background of the LBK genesis is yet unclear. Here we present 9 Y chromosomal and 84 mitochondrial DNA profiles from Mesolithic, Neolithic Starčevo and LBK sites (seventh/sixth millennia BC) from the Carpathian Basin and southeastern Europe. We detect genetic continuity of both maternal and paternal elements during the initial spread of agriculture, and confirm the substantial genetic impact of early southeastern European and Carpathian Basin farming cultures on Central European populations of the sixth–fourth millennia BC. Comprehensive Y chromosomal and mitochondrial DNA population genetic analyses demonstrate a clear affinity of the early farmers to the modern Near East and Caucasus, tracing the expansion from that region through southeastern Europe and the Carpathian Basin into Central Europe. However, our results also reveal contrasting patterns for male and female genetic diversity in the European Neolithic, suggesting a system of patrilineal descent and patrilocal residential rules among the early farmers.     

The origin and colonization history of the barley scald pathogen Rhynchosporium secalis

The origins of pathogens and their past and present migration patterns are often unknown. We used phylogenetic haplotype clustering in conjunction with model-based coalescent approaches to reconstruct the genetic history of the barley leaf pathogen Rhynchosporium secalis using the avirulence gene NIP1 and its flanking regions. Our results falsify the hypothesis that R. secalis emerged in association with its host during the domestication of barley 10,000 to 15,000 years ago in the Fertile Crescent and was introduced into Europe through the migration of Neolithic farmers. Estimates of time since most recent common ancestor (2500-5000 BP) placed the emergence of R. secalis clearly after the domestication of barley. We propose that modern populations of R. secalis originated in northern Europe following a host switch, most probably from a wild grass onto cultivated barley shortly after barley was introduced into northern Europe. R. secalis subsequently spread southwards into already established European barley-growing areas.