Search

The analysis of wild rice cell structures, tissues, organs, and other morphological characteristics and the development of identification markers for wild rice are the basis for identifying the origins and evolution of prehistorical rice agriculture. However, contemporary wild rice strains are often subject to gene introgression from domesticated rice cultivated by humans during the evolutionary process, which may affect the accuracy of wild rice identification markers. This means that how to eliminate the effects of gene introgression from domesticated rice and other plants on the identification of origin markers, and the purification of the morphological characteristics of wild rice have become critical in research to identify the origin of rice. In this study, we compared and analysed the phytolith morphologies of three common wild rice species ( Oryza rufipogon Griff .) from various habitats and one species of ectopically preserved homozygous common wild rice after six consecutive generations of self-crossing. We found that the morphology of the bulliform phytolith in the homozygous wild rice with reduced domestication gene introgression had three significant differences compared with native wild rice: (1) an overall reduction in size (body length decreased from 41.9 μm in VLnative to 38.6 μm in VLhomozygous); (2) an increase in the proportion of the long-stalked phenotype, with the ratio of B/A decreasing from 1.22±0.47 in B/Anative to 0.92±0.30 in B/Ahomozygous; and (3) a decrease in the number of fish-scale decorations, with the proportion of bulliform phytoliths with ≥9 fish-scale decorations reduced from 53.4% in native wild rice to 37.2% in homozygous wild rice. Thus, this study provides a reliable reference for the identification of rice origins using rice phytolith morphology.

Exploring whether diatom diversity in a lake sediment core is representative of that of the entire lake is important for determining the response of lake diatom diversity to global climatic warming. In this study, Yunlong Lake, an alpine lake located in Yunnan Province, Southwest China, was investigated to explore this question over both space and time. Spatially, we investigated diatom diversity patterns in 62 surface sediment samples from different locations and depth zones of Yunlong lake and found essentially constant diatom diversity across the entire lake basin. Temporally, we studied a well-dated sediment core from the lake center to explore whether long-term water-level changes influenced diatom diversity over the last ~ 100 years. Changes in the annual average sediment accumulation rates indicate that the water level of Yunlong Lake increased substantially after the construction of a dam. However, there is no obvious relationship between diatom diversity and water-level changes, which suggests at this site long-term water-level changes did not influence diatom diversity. Comparative analysis of the results for Yunlong Lake with those for other lakes indicates that for relatively strongly mixed lakes with a simple morphology and uniform shoreline microhabitat, such as Yunlong Lake, differences in water depth and changes in water level may not influence diatom diversity. In such cases, the diatom diversity from a sediment core is likely to be representative of that of the entire lake during specific time intervals. Therefore, such lakes may be optimal for studies of changes in past diatom diversity using sediment cores.

Archaeobotanical studies tend to concentrate on the evidence for specialised agricultural food production, with less attention directed towards the use of plant foods within hunter-gatherer contexts. Here, the authors present evidence for the exploitation of Canarium nuts from four late hunter-gatherer sites in southern China. Canarium nuts contributed to the inhabitants’ diets from as early as 9000 cal BP. They also identify new uses of Canarium, c. 4500–4400 cal BP, as ritual offerings in the context of the introduction of rice and millet farming. The results are examined in the context of Canarium use across the wider Asia-Pacific region.

Phytoliths in the inflorescence of Poaceae plants can be of high taxonomic value in some archaeological contexts and provide insight into plant taxonomy and crop domestication processes. In this study, phytoliths in every inflorescence bract of 38 common Panicoideae weeds and minor crops in China were studied. Based on dissection of the inflorescence into different bracts using a treatment that retained the phytoliths anatomical position, observations of inflorescence phytoliths types and distribution were described in detail. We found that Interdigitating, Blocky amoeboid, Rectangular dentate, and Elongate dendritic with multi tent-like arch tops were of higher taxonomic value than the other types in our studied species. Both morphological and morphometric traits of the Interdigitating were summarized and compared with previous studies; the findings suggested that genus level discrimination of some Paniceae species could be reliable, and tribe/species level discrimination might be feasible. The phytoliths in the involucre of domesticated and wild type Coix lacryma-jobi provided insight into the domestication process of this plant. Our data also indicated that phytolith production in the inflorescence bracts might be under the genetic and molecular control of inflorescence development. Thus, the findings of this study could assist future studies in plant taxonomy and archaeobotany.

International audience; Knowledge of the structures and intensities of past glaciations is crucial for understanding Quaternary palaeoclimatic evolution. Terrestrial molluscs are a reliable proxy of past environmental conditions and can provide specific climatic insights into glacials. Here we compare the climatic evolution of the last two glacials, based on mollusc fossils from the L2 and L1 loess units (equivalent to Marine Isotope Stages (MIS) 6 and 4-2, respectively) of the Xifeng and Luochuan sections of the Chinese Loess Plateau (CLP). The results show that both glacials had a tripartite structure but with different intensities, as indicated by variations in the abundance of the dominant cold-aridiphilous (CA) mollusc species, Vallonia tenera and Pupilla aeoli. The first stage, from~191 to 184 ka for MIS 6, and from~71 to 57 ka for MIS 4, was characterized by a cold, arid climate, as indicated by the abundance of V. tenera and P. aeoli, and the limited occurrence of thermo-humidiphilous (TH) species. The second stage, from~184 to 155 ka for MIS 6, and from~57 to 29 ka for MIS 3, was characterized by a relatively mild, humid climate, indicated bya decrease in V. tenera and P. aeoli, and an increase in TH species. The last stage, from~155 to 130 ka for MIS 6, and from~29 to 11.7 ka for MIS 2, experienced the coldest and driest conditions, as indicated by the dominance of V. tenera and P. aeoli in late MIS 6 and by the reduced occurrence of the grassland biomass, necessary for the growth of CA species, in MIS 2. The climate during MIS 2 was much colder and drier than that during late MIS 6. We suggest that the structures of the glacials were controlled mainly by insolation driven by changing astronomical configurations, amongst which obliquity likely played the major role. The different glacial intensities across the CLP may also have been related to variations in Northern Hemisphere ice sheets and the temperature of the tropical oceans.

The grass subfamily Pooideae originated in a temperate niche during the late Cretaceous; it is the largest Poaceae subfamily, consisting of almost 4,000 species, which are distributed worldwide. Pooideae responses to climate changes at different time scales, and different ecological zones are thus important in understanding Poaceae evolutionary processes and their relationship with climate change. In the study described in this article, we reconstructed Pooideae variability during the early Holocene, as inferred by a phytolith sequence from the Lower Yangtze in subtropical China. The phytolith assemblage was marked by three increases in Pooideae phytoliths, dated to ca 8.4–8.0, 7.8–7.6, and 7.4–7.2 ka BP (before present, 1950 AD), with each representing pronounced increases in Pooideae extent and distribution. All these increases were within age ranges that agreed well with the timing of weak Asian Monsoon events, at 8.2, 7.7, and 7.3 ka BP. The first Pooideae flourishing period in subtropical China was the most significant, lasting for approximately four centuries and being characterized by a double peak, which equated with an event at 8.2 ka. This suggested that cold and/or dry conditions—which occurred over a period of several hundred years and were linked to weakening of the Asian monsoon—probably caused Pooideae to flourish in the Lower Yangtze region. Comparison of two diagnostic trapezoid phytolith types—namely wavy and wavy narrow—which showed different changes between ca 8.4 and 8.0 ka BP, suggested that they responded differently to the climate change represented by the 8.2 ka event. Our phytolith records have provided not only new data clarifying the detailed Pooideae response to the 8.2 ka event but also a reliable index for past cold climates in subtropical China.

Yunlong Lake, a subtropical alpine lake in southwest China, was selected for a sediment trap diatom study between September 2013 and August 2015. Combining the results of meteorological records, wa...

The Peiligang culture is the earliest Neolithic culture in the middle Yellow River valley and represents the emergence of cereal farming in the region. Present records imply the concurrence of millet farming and mixed millet-rice farming in the Peiligang culture, but their spatial distribution pattern is still unknown, because of the there is a lack of comparative studies on crop remains from different sites. Here, we present the results of analyses of phytoliths and plant macroremains in archaeological sediments from four Peiligang culture sites, as well as an integration of crop records from nine other sites. These sites are classified into two types in terms of their geographical locations: those in alluvial plains and those in hilly lands. The results confirm the coexistence of millet and mixed farming in the Peiligang culture, rather than one or the other. Their spatial pattern involved millet farming in the hilly lands, with mixed farming done in the alluvial plains. Compared to the sites in the hilly lands, the sites in the alluvial plains have enough water sources and vast amounts of flat land, making it possible to cultivate rice and conduct mixed farming. In all Peiligang culture sites, regardless of any agricultural modes, common millet ( Panicum miliaceum ) was predominant among the crop assemblages. In the same climate background, the agricultural mode selection in different sites was mainly influenced by landform and hydrology. This spatial pattern of farming also reflects human adaptive subsistence practices, which respond to different natural circumstances.

China is one of the main global centers of origin of agriculture. Foxtail millet ( Setaria italica ), common millet ( Panicum miliaceum ), and rice ( Oryza sativa ) were the first crops to be domesticated in China. There remain many uncertainties and controversies in our current understanding of the chronology, locations, and plant types at the origins and the process of evolution of prehistoric millet and rice farming, and their relationships with climate change and human adaptation. This review summarizes the research progress made by Chinese scientists over the last decade on the origins and evolution of prehistoric agriculture. It highlights novel techniques and methods for identifying early crop remains, including plant macrofossils (carbonized seeds, spikelets), microfossils (phytoliths, calciphytoliths, starch, pollen), and biomarkers; new evidence on the origins, development, and spread of early agriculture; and research related to climate and environmental changes. Further, we pinpoint and discuss existing challenges and potential opportunities for further in-depth investigation of the origins and evolution of agriculture and the adaption of human activities to climate change.

Understanding the process of domestication and its relationship with environmental changes is fundamental to rice domestication research. The lower Yangtze region in China, with varied coastal environments and a flourishing Neolithic culture, was one of the major rice domestication centers in Asia. Here we present the results of 348 phytolith and 87 diatom samples from a 43.88-m-long core HMD1401 in the Ningshao Plain, southern part of the lower Yangtze. The results show that the study site was in a marine condition during the interval of ~10,000–7000 cal. yr BP. Marine regressed after ~7000 cal. yr BP, with occasional influences by sea water and flood. Rice was being domesticated in the Ningshao Plain at ~9600 cal. yr BP, and rice domestication experienced a protracted process that lasted for over 3500 years. The influence of marine condition might contribute to the prolonging of rice domestication. Relatively stable terrestrial condition and intensive human activities promoted rice domestication in the Ningshao Plain. The results provide an improved understanding of the interrelations between early rice domestication and Holocene environmental changes in East Asia.

A significant body of recent research shows that the first east–west transmission of cereal crops, Triticum spp. (wheat) and Hordeum spp. (barley) from the west and millets (Setaria italica, foxtail millet, and Panicum miliaceum, common millet) from the east, took place sometime around the start of the 5th millennium bp, with part of the most likely route lying along the Tianshan mountains in northern Xinjiang, China. Here the dominant economic adaptation is, and was in prehistory, not crop-based agriculture but transhumant pastoralism. The site of Luanzagangzi (ca. 3,300–2,900 cal bp) on the northern slope of the Tianshan is one of only a handful of Bronze Age sites in Xinjiang with evidence for well-established crop cultivation. In this paper, we report on ten samples collected for phytolith analysis from a 4 m deep profile at Luanzagangzi. The results show evidence that a range of cereal crops was being grown (multi-cropping), Triticum spp., Hordeum spp., Setaria italica and Panicum miliaceum. Pooideae, Paniceae woody plants, Phragmites (reed) and Cyperaceae (sedges) were presumably also exploited for subsistence purposes in this area. We speculate that the strategy of growing a range of crops, wheat/barley, common millet and foxtail millet was adopted by the Bronze Age population in this region as a supplement to herding. The findings of this study help us to understand the dispersal of cultivation strategies across the Eurasian steppe via the Xinjiang region, and the communication between China and the West in the late Bronze Age.

Recent studies have shown that the proportion of rice bulliform phytoliths with ≥9 fish-scale decorations can be used as a criterion to differentiate wild rice from its domesticated counterpart. The analysis of rice bulliform phytoliths recovered from 38 samples collected from eight archaeological sites dated to around 10,000–2200 BP suggests that the process of rice domestication in the Lower Yangtze River region lasted for around 6000 years and can be divided into three stages. Stage I was from around 10,000 to 6500 BP. The process of domestication was very slow, and even went backwards. Stage II was between 6500 and 5600 BP, when the process was accelerated. During stage III, from 4500 to 2200 BP, the domestication process eventually resulted in the breed of the modern rice.

Using phytolith analysis from a well-dated and high-resolution sediment sequence in the apex of northern Yangtze Delta, we investigate environmental changes, the rise and decline of rice exploitation and possible impacts of environment on rice exploitation during the early mid-Holocene. The phytolith sequence documents a relatively warm and dry interval during ca.9000 to 8200 cal yr BP, followed by climatic amelioration before 7200 cal yr BP. Phytolith evidence indicates that rice exploitation at the apex of northern Yangtze Delta began at 8200 cal yr BP, flourished by 7700 cal yr BP and ceased after 7400 cal yr BP. The first emergence of marine diatom species approximately 7300 cal yr BP likely indicates an accelerated sea-level rise. The apparent correlation of the initiation of rice exploitation with climatic amelioration during the early mid-Holocene suggests that climatic changes may have played an important role in facilitating rice exploitation. Both the ideal climatic conditions and stable sea level enabled flourishing rice exploitation during 8200 to 7400 cal yr BP. Although the climate remained warm and wet after 7400 cal yr BP, local sea-level rise possibly led to the termination of earlier rice exploitation at this site of the northern Yangtze Delta.

In the last decade, our understanding of rice domestication has improved by new archaeological findings using advanced analytical techniques such as morphological and morphometric analyses on rice grains, spikelet bases and phytoliths, and ancient DNA analysis on rice remains. Previous studies have considered the size of rice bulliform phytoliths as a proxy for tracking the domestication process. These phytoliths are often abundant and well preserved in sediments, and their shape is under the control of numerous genes, which may shift toward larger sizes by genetic mutation in domestication. Therefore, it has been assumed that the bulliforms of domesticated rice are usually larger than those of wild ones; however, morphometric data supporting this assumption are lacking in the literature, thereby requiring additional evidence to test its veracity. In this study, the vertical and horizonal lengths of bulliform phytoliths were measured in four rice species (domesticated Oryza sativa and wild Oryza rufipogon, Oryza officinalis, and Oryza meyeriana) from different regions of southern China. We found that the bulliform morphometric data of wild and domesticated rice overlapped and that there was no statistically significant difference between them. Therefore, bulliform size could not be used as a diagnostic indicator to distinguish domesticated rice from wild species and is a supporting rather than conclusive proxy for determining the domesticated status of rice in archaeological research. We further found that larger rice bulliform sizes likely occurred at the locations with higher temperature, precipitation, and water levels, indicating hydrothermal environment is an alternative factor influencing the size of rice bulliform phytoliths. For further archaeological use of an increasing size trend of bulliform phytoliths to reveal the process of rice domestication, we present some suggestions for controlling the influence of hydrothermal factors. Even so, the combination of bulliform phytolith size with other established criteria is strongly suggested to provide precise identification of wild and domesticated rice in future research.

In this paper, we report late Pleistocene to Holocene changes in the shell size and age structure of the gastropod, Opeas striatissimum, in two loess profiles in the Chinese Loess Plateau, spanning the past 27 ka. During the interval of ~17–8 ka, in response to climatic warming, we observed marked increases in shell dimensions and a more diverse age structure (age classes), as well as a ~20% increase in the number of adult individuals. Shell growth and enhanced survival from juvenile to adult, in turn, resulted in an increase in the population size, which reached a maximum during the interval ~8–3 ka, corresponding to the Holocene Climatic Optimum. We also observed an abrupt decrease in shell height and related significant decreases in the total number of individuals of Opeas striatissimum and adult individuals at the time of the Younger Dryas cold climatic event. We suggest that the observed morphologic and demographic changes observed for Opeas striatissimum reflect changes in the growing season, linked to changes in monsoon rainfall and climate stability, in response to climate fluctuations from the late Pleistocene to the Holocene. Our study provides a long-term perspective that helps refine mechanistic population models of invertebrates in the face of future climate change.

Reconstructing and quantifying human impacts is an important step in understanding how, when, and to what extent humans have changed terrestrial ecosystems via agricultural land use during the Holocene. However, the use of soil-faunal indicators and an associated quantitative model of land use intensity to study anthropogenic disturbance is relatively poorly developed. In this study we collected 139 samples of soil-dwelling snails from urban land and human settlements, cultivated land, modified and natural vegetation mosaics, and natural habitats in northern China, in order to characterize the snail assemblages in human-modified habitats. The results show that cultivated land and planted forest are mainly dominated by snails of Cathaica fasiola, Bradybaena ravida, Vallonia tenera, etc., while natural habitats are characterized by an even distribution of members of the families, such as Ariophantidae, Cochlicopidae, Pupillidae, Subulinidae. Canonical correspondence analysis indicates that human activity (quantified by the human influence index, HII) is one of the most important factors shaping the composition of snail fauna in man-modified habitats. There is a significant relationship between modern snail data and HII, and the transfer function established by weighted-averaging partial least squares (WA-PLS) model for HII exhibits a good statistical performance. We then applied the calibration model to a fossil snail record spanning the last 12 kyr from the Chinese Loess Plateau (CLP). The reconstructed HII increases slightly at ∼5 ka and abruptly at ∼2 ka, coinciding with increases in the human population of the CLP, local cultural development, and human-induced changes in vegetation cover. Our quantitative reconstruction indicates that human activities, via agricultural activity, may have permanently altered natural ecosystems and the soil fauna for at least the last two millennia.

Echinochloa was an important prehistoric food crop of early agriculture in Asia. Macro-remains can be used to identify Echinochloa. However, when few macro-remains are available, phytolith analysis can be performed. In this study, we examined the phytolith morphology of the glumes, lemmas, and paleas from the inflorescence bracts of nine Echinochloa species from different regions of China and obtained diagnostic, morphological, and morphometric characteristics for Echinochloa. Phytoliths in Echinochloa are different from those in most known crops except those in Setaria italica and Panicum miliaceum. We found the following two diagnostic features within an epidermal silica layer that can be used to distinguish Echinochloa sp. from S. italica and P. miliaceum: (1) the β-type undulated patterns with constricted top of the undulation amplitude and (2) the discriminant functions based on the morphometric data of the β-type undulated patterns, which suggested that 94.9 % of the cross-validated data were correctly classified into Echinochloa, S. italica, and P. miliaceum. Thus, we established the phytolith identification criteria for Echinochloa; this could have important implications in plant taxonomy, archaeobotany, and plant domestication.

Domestication of broomcorn millet (Panicum miliaceum) is one of the most significant events in prehistoric East Asia, providing sufficient food supply for the explosive growth of Neolithic populations and the transition into complex societies. However, to date, the process of broomcorn millet domestication is still largely unknown, partly due to the lack of clear diagnostic tools for distinguishing between millet and its related wild grasses in archaeological samples. Here, we examined the percentage of silicified epidermal long-cell undulated patterns in the glume and palea from inflorescence bracts in 21 modern varieties of broomcorn millet and 12 weed/feral-type Panicum ruderale collected across northern China. Our results show that the percentage of ηIII patterns in domesticated broomcorn millet (23.0% ± 5.9%; n = 63) is about 10% higher than in P. ruderale (10.8% ± 5.8%; n = 36), with quartiles of 17.2–28.3% and 5.1–15.5%, respectively. Owing to the increase in ηIII pattern percentage correlates significantly with a decrease in the grain length/width ratio, in the absence of exact wild ancestors of broomcorn millet, the characterization of phytolith differences between P. ruderale and P. miliaceum thus becomes an alternative approach to provide insight into origin of broomcorn millet.

The process of rice domestication has been studied for decades based on changing morphological characteristics in assemblages of both macroremains, such as charred seeds and spikelet bases, and microremains, such as phytoliths, esp. bulliform and double-peaked phytoliths. The applicability of these indicators in determining if a specific assemblage is wild or domesticated, however, is rarely discussed. To understand the significance of these indicators in the determination of domestication, we collected 38 archaeological samples from eight Neolithic sites, dating from 10-2ka BP, in the lower Yangtze River region to analyze and compare the changes of these different indicators over eight thousand years. The data demonstrate that the comprehensive analysis of multiple indicators may be the best method to study the process of rice domestication developed thus far. An assemblage of rice remains can be identified as domesticated forms if they meet the following criteria simultaneously: 1) the proportion of domesticated-type bulliform phytoliths is more than 73%; and 2) the proportion of domesticated-type rice spikelet bases is higher than 75%. Furthermore, we found that each indicator tends to change steadily and gradually over time, and each stabilized at a different time, suggesting that the characteristics of domesticated rice developed slowly and successively. Changes of multiple indicators during the period between 10,000–2,000 yr BP indicate that the process of rice domestication in the lower Yangtze River region lasted as long as ca. 6,000 years during the Neolithic, and can be divided into three stages with the turning points in the middle Hemudu-late Majiabang culture (6,500–5,800yr BP) and the late Liangzhu culture (4,600–4,300yr BP).

Past environmental changes based on diatom relative abundances have been inferred from the maar Lake Erlongwan in northeast China. The limnology of Lake Erlongwan is affected by the strongly seasonal regional climate. The composition of diatom assemblages, in turn, responds to changes in the seasonal duration of ice cover in winter, water-column turnover in spring and autumn, and thermal stratification in summer. Statistical analysis of the sedimentary diatom assemblages reveals three significant stratigraphic zones over the past 1000 yr. The highest abundance of the planktonic speciesDiscostellaspecies occurs between AD 1050 and 1400 and suggests an annual ice-free period of long duration and well-developed summer stratification of the water column. This planktonic diatom peak between ca. AD 1150 and 1200 suggests that this period was the warmest over the past 1000 yr. The interval between AD 1400 and 1800 is marked by a decline in planktonic diatoms and suggests shorter duration of the ice-free season, weaker water stratification and possibly generally cold conditions. After AD 1800 relative abundances of planktonic diatoms, includingPuncticulata praetermissaandAsterionella formosa, increase again, which indicates lengthening of the duration of the annual ice-free period and a stronger overturn of the water column. All these data imply that the pattern of the seasons is different between the MWP and the 20th century.

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. (C) 2011 Elsevier Ltd. All rights reserved.

Rice (Oryza sativa) is regarded as the only grass that was selected for cultivation and eventual domestication in the Yangtze basin of China. Although both macro-fossils and micro-fossils of rice have been recovered from the Early Neolithic site of Shangshan, dating to more than 10,000 years before present (BP), we report evidence of phytolith and starch microfossils taken from stone tools, both for grinding and cutting and cultural layers, that indicating barnyard grass (Echinochloa spp.) was a major subsistence resource, alongside smaller quantities of acorn starches (Lithocarpus/Quercus sensu lato) and water chestnuts (Trapa). This evidence suggests that early managed wetland environments were initially harvested for multiple grain species including barnyard grasses as well as rice and indicate that the emergence of rice as the favoured cultivated grass and ultimately the key domesticate of the Yangtze basin was a protracted process.

Bulliform phytoliths play an important role in researching rice origins as they can be used to distinguish between wild and domesticated rice. Rice bulliform phytoliths are characterized by numerous small shallow fish-scale decorations on the lateral side. Previous studies have shown that domesticated rice has a larger number of these decorations than wild rice and that the number of decorations ≥9 is a useful feature for identifying domesticated rice. However, this standard was established based on limited samples of modern rice plants. In this study, we analyzed soil samples from both wild and domesticated rice paddies. Results showed that, in wild rice soil samples, the proportion of bulliform phytoliths with ≥9 decorations was 17.46% ± 8.29%, while in domesticated rice soil samples, the corresponding proportion was 63.70% ± 9.22%. This suggests that the proportion of phytoliths with ≥9 decorations can be adopted as a criterion for discriminating between wild and domesticated rice in prehistoric soil. This indicator will be of significance in improving the application of fish-scale decorations to research into rice origins and the rice domestication process.

Diatom data of 192 surface sediment samples from the marginal seas in the western Pacific together with modern summer and winter sea surface temperature and salinity data were analyzed. The results of canonical correspondence analysis show that summer sea-surface salinity (SSS) is highly positively correlated with winter SSS and so is summer sea-surface temperature (SST) with winter SST. The correlations between SSSs and SSTs are less positively correlated, which may be due to interactions of regional current pattern and monsoon climate. The correlations between diatom species, sample sites and environmental variables concur with known diatom ecology and regional oceanographic characters. The results of forward selection of the environmental variables and associated Monte Carlo permutation tests of the statistical significance of each variable suggest that summer SSS and winter SST are the main environmental factors affecting the diatom distribution in the area and therefore preserved diatom data from down core could be used for reconstructions of summer SSS and winter SST in the region.

Prehistoric groundstone tools including slabs (metate, mo-pan) and mullers (mano, mo-bang) are often considered to be tools that were used to process cereals in ancient China. Most archaeologists believe that groundstone tools are indicators of an agrarian economy. This study employed starch grain analysis to examine a slab and a muller excavated from the Shangzhai Site (7500-7000 cal a BP), Beijing. Identifiable starch grains recovered from the stone tools were classified into 9 genera and 12 species, most of which were from acorns and foxtail millets. Remains from the oak species Q. mongolicus, Q. acuttssima, and Q. dentate were identified as well as a few starch grains from broomcorn (Panicum miliaseum) and bean (Vigna sp.). Other starch grains were from unidentifiable roots and grasses. A variety of starch grains indicates that the grinding stone tools were used to process not only cereals, but also other seeds or roots that had to be ground or husked, thus bringing into question the aforementioned cereal hypothesis. Because the numbers of starch grains from nuts and millets were so large, both gathering and cultivation might have been important economic patterns before 7000 years ago in Beijing area. Moreover, the starch remains are derived from plants that indicate that the paleoclimate of Beijing was wetter and warmer than today’s.

A large amount of carbonized plant remains were discovered in one of the outer burial pits of the Han Yangling Mausoleum, which was built more than 2000 years ago for the Jing Emperor, Liu, Qi (188—141 cal a BC), the fourth emperor of the Western Han Dynasty. The remains are identified by phytolith analysis and macrofossil morphological features. Seeds from foxtail millet (Setaria italica), broomcorn millet (Panicum miliaceum), rice (Oryza sativa) and chenopod (possible Chenopodium giganteum) are identified, suggesting that these four crops might have been the staple plant foods in the capital area (Guanzhong area), Shaanxi Province during the Early Western Han Dynasty. Chenopods were often considered as weeds since they have only been rarely found as carbonized seeds in prehistoric sites. This is the first time such a large amount of seeds has been found at a site, which provides strong material evidence for chenopod cultivation with a long history in China. Wheat was thought to be promoted and popularized in the Guanzhong area since the Wu Emporor, Liu, Che (156—87 cal a BC), the fifth emperor of the Western Han Dynasty. No wheat was found at this site, which supports the historical document record that wheat was still secondary in the diet and agrarian economy before the Wu Emperor’s reign.

The geographical distribution of dominant plant species in China was georeferenced and climatic variables were interpolated into all grids. Accordingly, the percentage distributions of principal pollen taxa based on 1860 surface pollen sites in China were selected and the related climate values were interpolated with the same method. The geographical and climatic comparison between the two datasets indicated that the climate threshold of most pollen taxa from surface pollen is coherent with plant distributions. The climatic envelopes of dominant plant are mostly accordant with those of pollen taxa at certain levels. However, some distinct offsets of the climate ranges exist between the two datasets for most pollen taxa identified at family level, such as Ericaceae, Asteraceae, Poaceae and Chenopodiaceae. The present study provides for the first time rich information on temperature and precipitation in relation to pollen and plant distribution based on the datasets on a continental scale useful for global ecological modeling and Quaternary palaeoclimate reconstruction.

Fossil rice phytoliths have been identified from a lateglacial to Holocene sequence of epicontinental sediments in the East China Sea that were probably transported by the Yangtze River from its middle and/or lower reaches. The rice phytoliths occurred first in the sequence at about 13 900 cal. yr BP and disappeared during the period of 13 000–10000 cal. yr BP, implying the earliest domesticated cereal crops of the world ever reported. Based on the records of phytoliths, pollen, diatoms and foraminifera from the sequence, the climate between 13 000 and 10 000 cal. yr BP was notably colder (Younger Dryas). The coincidence of disappearance of domesticated rice phytoliths with cold climate conditions may suggest a great climatic influence on human activities during that time. Warmer and wetter conditions during the period 13900 to 13000 cal. yr BP and after 10000 cal. yr BP have probably favoured rice domestication in the area.

We present here the first high-resolution pollen record of vegetation response to interactions of hurricane and fire disturbances over the past 1200 yr from a small lake in Alabama on the Gulf of Mexico coast. The paleo tempestological record inferred from the over wash sand layers suggests that the Alabama coast was directly struck by Saffir–Simpson category 4 or 5 hurricanes twice during the last 1200 yr, around 1170 and 860 cal yr BP, suggesting an annual landfall probability of 0.17% for these intense hurricanes. The charcoal data suggest that intense fires occurred after each of these hurricanes. The pollen data suggest that populations of halophytic plants (Chenopodiaceae) and heliophytic shrubs (Myrica) expanded after the hurricane strikes, probably due to saltwater intrusion into the marshes and soil salinization caused by over wash processes. Populations of pines (Pinussp.) decreased significantly after each intense hurricane and the ensuing intense fire, suggesting that repeated hurricane–fire interactions resulted in high tree mortality and probably impeded recruitment and recovery. Our data support the hypothesis that the likelihood and intensity of fire increased significantly after a major hurricane, producing responses by vegetation that are more complex and unpredictable than if the disturbance agents were acting singly and independently.

Phytoliths represent one of the few available altitudinal vegetation proxies for mountain ecosystems. This study analyzed 41 topsoil phytolith samples collected from five altitudinal zones in the southern Himalaya as far as and beyond, the timberline, from tropical forest (up to 1,000 m a.s.l.) to subtropical forest (1,000–2,000 m a.s.l.), to temperate forest (2,000–3,000 m a.s.l.), to subalpine forest (3,000–4,100 m a.s.l.) and finally to alpine scrub (4,100–5,200 m a.s.l.). The statistical results show a good correlation between phytolith assemblages and these five altitudinal vegetation zones: the five phytolith assemblages identified effectively differentiated these five altitudinal vegetation zones. In particular, coniferous phytoliths accurately indicated the timberline. Additionally, we tested the phytolith index Ic (a proxy for estimating the percentage of Pooideae vis-à-vis the total grass content) as a quantifier of phytolith variety versus altitude. Ic increased along altitude, as expected. An investigation of phytoliths provided an initial basis for the analysis of the composition of gramineous vegetation. Furthermore, redundancy analysis and discriminant analysis also suggested a significant correlation between phytolith assemblages and altitude. Our research therefore provides an up-to-date analogue for the reconstruction of changes to palaeovegetation and palaeoaltitude in mountainous areas.

The history of tea is poorly known, mainly due to the questionable identification of decayed tea plants in archaeological samples. This paper attempts to test the utility of calciphytoliths (calcium oxalate crystals) for the identification of tea in archaeological samples. It provides the first survey of the macropatterns of calciphytoliths in several species of Theaceae and common non-Theaceae plants. Crystals were extracted from 45 samples of tea, Theaceae and common non-Theaceae plants and detected microscopically between crossed polarizers. In tea plants, druse and trichome base are the most distinctive crystals. Druses have the smallest diameter (11.65 ± 3.64 μm) and trichome bases have four distinctive straight and regular cracks, similar to a regular extinction cross. The results provide morphological criteria for distinguishing tea from other plants, specifically the presence of identifiable druses together with calcified trichome bases. The implications are significant for understanding the history of tea and plant exploitation, especially for plants for which the preservation of macrofossils is poor.

Plant specimens are collected from the areas between latitude 27 ° 42′N and 40 ° 57′N, and longitude 88 ° 93′E and 103 ° 24′E, with an altitudinal range from 2210 to 5050 m above the sea level in Qinghai-Tibetan Plateau. The stable carbon isotope analysis indicates that two of Chenopodiaceae and six of Poaceae in the samples are C4 plants. Four of the C4 plants are found in 11 spots with altitudes above 3800 m, and Pennisetum centrasiaticum, Arundinella yunnanensis and Orinus thoroldii are present in six spots above 4000 m, even up to 4520 m. At low CO2 partial pressure, that sufficient energy of high light improving C4 plant’s tolerance of low temperature and precipitations concentrating in growing season probably are favorable for C4 plants growing at high altitude in Qinghai-Tibetan Plateau.

Thirty-four grass species were collected for phytolith analysis from a variety of coastal environments in the southeastern USA (Georgia, Florida, and Louisiana), including salt marshes, freshwater/brackish marshes, pine/oak forests, maritime hardwood forests, and sand dunes. Phytoliths produced by these modern grasses include a large diversity of shapes and types. We propose a preliminary relationship between modern coastal plant communities and their predominant phytolith contents. The dominant grasses of coastal sand dunes, such as Uniola paniculata, produce primarily flat tower and two-horned tower phytoliths. Rondel/ saddle ellipsoid phytoliths are mainly produced by Spartina alterniflora, the most common plant in coastal salt marshes. Rondel and spool/horned tower phytoliths are common in brackish marsh grasses. Plants from interdune meadow produce primarily dumbbell phytoliths, as well as small cross and Cyperaceae-type phytoliths. These results provide a basis for the interpretation of fossil phytolith assemblages and the reconstruction of coastal environmental changes. 2003 Elsevier Ltd. All rights reserved.

Phytolith analysis of grasses is a useful tool in palaeoenvironmental and archaeobotani- cal research. Lobate phytolith is one of the most important morphotypes of grass phytoliths. This study describes morphological variations of diag- nostic lobate phytoliths and produces a tentative classification scheme based on 250 modern grass species from China and the south-eastern U.S.A. Eighty-five grass species were found to contain lobate phytoliths. They are derived mainly from Panicoideae, but also include the Chloridoideae, Oryzoideae and Arundinoideae subfamilies. Twenty-five lobate morphological types were observed from different subfamilies, genera or tribes of grasses, based on two important param- eters: (1) the length of the lobate shank and (2) the shape of the outer margin of the two lobes. The identification of grass tribe or even genus is possible based on the differences in lobate shape parameters or the composition of assemblages. However, not all of the lobate assemblages have a definite relationship with the genera that produce them, because grasses can only produce a limited range of lobate shapes that often over- lap from one genus to another. Several C3 grasses and Chloridoideae subfamily grasses also produce characteristic lobate phytoliths. The variations of lobate morphologies can be related to environmen- tal factors, especially moisture. Typical hygrophytic grasses tend to yield lobate phytoliths with very short shank, whereas typical xerophytic grasses tend to produce lobate phytoliths with a very long shank. The potential link between phytolith morphology, grass taxonomy and environmental conditions opens the possibility that phytolith morphology may be used as a proxy in palaeocli- matic reconstruction.

Mollusk remains are abundant in archaeological sites in the Guanzhong Basin of Northwestern China, providing good opportunities for investigations into the use of mollusks by prehistoric humans. Here we report on freshwater gastropod and bivalve mollusks covering the time interval from about 5600 to 4500 cal. yrs BP from sites of Mid-Late Neolithic age. They are identified as Cipangopaludina chinensis and Unio douglasiae, both of which are currently food for humans. The shells are well preserved and have no signs of abrasion. They are all freshwater gastropods and bivalves found in pits without water-reworked deposits and have modern representatives which can be observed in rivers, reservoirs, and paddy fields in the studied region. Mollusk shells were frequently recovered in association with mammal bones, lithic artifacts, and pottery. These lines of evidence indicate that the mollusks are the remains of prehistoric meals. The mollusk shells were likely discarded into the pits by prehistoric humans after the flesh was eaten. However, these mollusk remains may not have been staple food since they are not found in large quantities. Mollusk shell tools and ornaments are also observed. Shell tools include shell knives, shell reaphooks and arrowheads, whereas shell ornaments are composed of pendants and loops. All the shell tools and ornaments are made of bivalve mollusks and do not occur in large numbers. The finding of these freshwater mollusk remains supports the view that the middle Holocene climate in the Guanzhong Basin may have been warm and moist, which was probably favorable to freshwater mollusks growing and developing in the region.

Carbon isotope ratio (δ13Corg) values of organic matter in lake sediments are commonly used to reconstruct environmental change, but the factors which influence change are varied and complex. Here we report δ13C values for sediments from Erlongwan maar lake in northeast China. In this record, changes in δ13C cannot be explained by simple changes in aquatic productivity. Instead, values were likely influenced by differences in the ratio between planktonic and benthic algae, as indicated by the remains of diatoms. This is because the variation of δ13Corg in algae from different habitats is controlled by the thickness of the diffusive boundary layer, which is dependent on the turbulence of the water. Compared with benthic algae, which grow in relatively still water, pelagic algae are exposed to greater water movement. This is known to dramatically reduce the thickness of the boundary layer and was found to cause even more severe δ13C depletion. In Erlongwan maar lake, low values were linked to the dominance of planktonic diatoms during the period commonly known as the Medieval Warm Period. Values gradually increased with the onset of the Little Ice Age, which we interpret as being driven by an increase in the proportion of benthic taxa, due to effect of the colder climate. The increase in planktonic diatoms at the end of the Little Ice Age, linked to higher temperature and a reduction in ice cover, resulted in a further decline in δ13Corg.

The Peiligang Culture (9000-7000 cal. yr BP) in the Middle Yellow River region, North China, has long been considered representative of millet farming. It is still unclear, however, if broomcorn millet or foxtail millet was the first species domesticated during the Peiligang Culture. Furthermore, it is also unknown whether millet was cultivated singly or together with rice at the same period. In this study, phytolith analysis of samples from the Tanghu archaeological site reveals early crop information in the Middle Yellow River region, China. Our results show that broomcorn millet was the early dry farming species in the Peiligang Culture at 7800 cal. yr BP, while rice cultivation took place from 7800 to 4500 cal. yr BP. Our data provide new evidence of broomcorn millet and rice mixed farming at 7800 cal. yr BP in the Middle Yellow River region, which has implications for understanding the domestication process of the two crops, and the formation and continuance of the Ancient Yellow River Civilization.

Foxtail millet (Setaria italica) is one of the oldest domesticated cereal crops in Eurasia, but identifying foxtail millets, especially in charred grains, and differentiating it from its wild ancestor, green foxtail (Setaria viridis), in the archaeobotanical remains, is still problematic. Phytolithic analysis provides a meaningful method for identifying this important crop. In this paper, the silicon structure patterns in the glumes, lemmas, and paleas from inflorescence bracts in 16 modern plants of foxtail millet and green foxtail from China and Europe are examined using light microscopy with phase-contrast and a microscopic interferometer. Our research shows that the silicon structure of ΩIII from upper lemmas and paleas in foxtail millet and green foxtail can be correspondingly divided into two groups. The size of ΩIII type phytolith of foxtail millet is bigger than that from green foxtail. Discriminant function analysis reveals that 78.4% of data on foxtail millet and 76.9% of data on green foxtail are correctly classified. This means certain morphotypes of phytoliths are relatively reliable tools for distinguishing foxtail millet from green foxtail. Our results also revealed that the husk phytolith morphologies of foxtail millets from China and Eastern Europe are markedly different from those from Western Europe. Our research gives a meaningful method of separating foxtail millet and green foxtail. The implications of these findings for understanding the history of foxtail millet domestication and cultivation in ancient civilizations are significant.

The origin of millet from Neolithic China has generally been accepted, but it remains unknown whether common millet ( Panicum miliaceum ) or foxtail millet ( Setaria italica ) was the first species domesticated. Nor do we know the timing of their domestication and their routes of dispersal. Here, we report the discovery of husk phytoliths and biomolecular components identifiable solely as common millet from newly excavated storage pits at the Neolithic Cishan site, China, dated to between ca. 10,300 and ca. 8,700 calibrated years before present (cal yr BP). After ca. 8,700 cal yr BP, the grain crops began to contain a small quantity of foxtail millet. Our research reveals that the common millet was the earliest dry farming crop in East Asia, which is probably attributed to its excellent resistance to drought.

Foxtail millet (Setaria italica) and Common millet (Panicum miliaceum) are the oldest domesticated dry farming crops in Eurasia. Identifying these two millets in the archaeobotanical remains are still problematic, especially because the millet grains preserve only when charred. Phytoliths analysis provides a viable method for identifying this important crop. However, to date, the identification of millet phytoliths has been questionable, because very little study has been done on their morphometry and taxonomy. Particularly, no clear diagnostic feature has been used to distinguish between Foxtail millet and Common millet. Here we examined the anatomy and silicon structure patterns in the glumes, lemmas, and paleas from the inflorescence bracts in 27 modern plants of Foxtail millet, Common millet, and closely related grasses, using light microscopy with phase-contrast and microscopic interferometer. Our research shows that five key diagnostic characteristics in phytolith morphology can be used to distinguish Foxtail millet from Common millet based on the presence of cross-shaped type, regularly arranged papillae, Omega-undulated type, endings structures of epidermal long cell, and surface ridgy line sculpture in the former species. We have established identification criteria that, when used together, give the only reliable way of distinguishing between Foxtail millet and Common millet species based on their phytoliths characteristics, thus making a methodological contribution to phytolith research. Our findings also have important implications in the fields of plant taxonomy, agricultural archaeology, and the culture history of ancient civilizations.

[1] We present a continuous record of fossil diatoms from Huguang Maar Lake (HML) in southeastern China, spanning the time interval 17,500 to 6000 calendar years (cal years) B.P. The seasonal change in relative abundance of the dominant diatom taxa, Aulacoseira and Cyclotella species, can be used as a proxy of the strength of winter monsoon winds (WMW), which is supported by the results of a sediment trap experiment in HML and by an extensive review of the literature on the autoecologies of these species. In the sediment, high C. stelligera abundance and high-diatom concentration, which indicate warm conditions and low wind-driven turbulence of the water column, characterize an interval equivalent to the Greenland Interstadial 1. This is followed by an interval with low-diatom concentration and with assemblages dominated by Aulacoseira species, which suggests high wind-driven turbulence and therefore strong WMW. This interval corresponds with the Greenland Stadial 1. During the early and middle Holocene, another two episodes with strong WMW are evident from the data between 10,000 and 8500 and between 7000 and 6000 cal years B.P. The diatom record implies that strong winter monsoon episodes not only occurred during the last glacial-Holocene transition but also during the Holocene “thermal maximum.”

A remarkable find allows the reconstruction of the earliest recorded preparation of noodles.

High-resolution analyses of terrestrial mollusks from two loess sequences in the Chinese Loess Plateau provide continuous evidence of paleoecosystem and paleoclimate processes through the recent three glacial-interglacial cycles. Systematic fluctuations in thermal-humidiphilous mollusk type (Punctum orphana) indicate that the strength of the SE Asian summer monsoon is sensitive to orbital forcing at the obliquity and precession periods (41 and 23 kyr, respectively). In contrast, the cold-aridiphilous mollusk (Vallonia tenera and Pupilla aeoli) variability displays a different pattern. The strongest powers are centered at about 100 kyr and 41 kyr periods, which drive the major period of winter monsoon variations in the Chinese loess. These different responses to winter and summer monsoon in the Loess Plateau of China suggest that both of these monsoon systems are tightly coupled in the 41 kyr cycle, but are not coincident relative to the precession (19-23 kyr) and 100 kyr cycles. The relationship between the winter and summer monsoons is not a simple model reflecting a seesaw pattern.