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The two-step green synthesis of highly stable and well-dispersed copper nanoparticles are obtained by the two-step dehydrogenation mechanism of l-ascorbic acid. The copper nanoparticles can be applied in the biomedicine and flexible electronics.

The mechanisms of the origin and dispersal of millet agriculture in northern China are poorly understood. We used plant macroremains, stable isotope compositions of human bone collagen, and pollen records from the Sitai site to reconstruct changes in subsistence strategies and their relationship with the ecological environment from the early to middle Holocene on the Inner Mongolian Plateau in northern China. Charred weed-like seeds, the bones of small mammals, eggshell fragments, together with microliths, indicate the practice of hunter-gatherer subsistence strategies during 10,500–10,200 cal yr BP. Deciduous broadleaved forest-steppe vegetation was present around the Sitai site during the early middle Holocene (8000–7000 cal yr BP). Additionally, isotopic compositions of human bones and plant remains reveal that millet agriculture and hunting-gathering appeared in the early middle Holocene. The spread of millet agriculture on the Inner Mongolian Plateau was likely favored by an increase in precipitation between 8000 and 7000 cal yr BP. The development of millet agriculture on the Inner Mongolia Plateau and the Loess Plateau was the prelude to its subsequent spread to the Tibet Plateau.

Pollen analysis is rarely applied to cave sediments because of the complex range of processes influencing the origin, transport and taphonomy of pollen grains in caves. In order to evaluate the potential of pollen spectra from within caves for vegetation reconstruction, we compared the modern pollen from the interior and exterior of four caves in Guangxi and Guizhou, in southwestern China. The results show that the pollen spectra from within the sack-shaped caves, and from the front and middle of a long, narrow caves, were similar to those outside the caves, and therefore that the pollen spectra from these caves can reliably be used for palaeovegetation reconstruction. Wind is the major transport medium for the pollen entering caves, but animals may be additional transport medium. In addition, cave geometry is likely to be responsible for the observed spatial distribution of pollen concentrations in caves. In long, narrow caves, the entrance is the optimum sampling location for pollen analysis; however, in sack-shaped caves an optimum sampling location cannot be specified due to the gradient in pollen concentration between the entrance and the rear, together with its irregular distribution.

Pollen evidence from a 25.3-m-long section (~2.2–0.41 Ma) in the Jinyuan Cave, Liaodong Peninsula, indicates that from the Early–Middle Pleistocene, the climate showed a trend of gradual cooling and drying, with obvious fluctuations. The vegetation was represented by temperate broad-leaved forest from ca. 2.2 to 1.87 Ma, suggesting a relatively warm and humid climate. The period from 1.87 to 1.82 Ma witnessed an obviously cold and dry event, and coniferous and broadleaved mixed forests developed from 1.82 to 1.76 Ma. From 1.52 Ma to the Mid-Pleistocene Transition (MPT), the vegetation was dominated by forest steppe, and the climate became cold in the later stage. During the 0.59–0.41 Ma period, steppes developed, and the climate was cold and arid. At the same time, with climate variation, the faunal communities also changed obviously and co-evolved with vegetation types. In the early stage of the Early Pleistocene, the warm and humid climate was related to the presence of a wide range of thermophilous animals. From 1.7 to 1.5 Ma, the transition from forest to forest steppe might have promoted the emergence of certain grassland-adapted animals. During the MPT, grassland-adapted animals became dominant due to the flourishing forest steppe vegetation. The Middle Pleistocene witnessed the expansion of steppe and animals adapted to the arid grassland environment at that time.

Recently, rich fossiliferous deposits dated to the late Cenozoic have been discovered from Jinyuan Cave at Luotuo Hill, an extremely large-sized cave site situated within in the Dalian Puwan Economic Zone of Dalian Municipality, Liaoning Province in Northeast China. Abundant and diverse vertebrate fossils unearthed from different fossiliferous layers of Jinyuan Cave, a site of enormous size with a sedimentary thickness of over 40 m and its deposits can be roughly divided into three fossiliferous deposit units, altogether containing six fossiliferous layers belonging to different ages from the Late Pliocene to the Middle Pleistocene. Based on a combination of biostratigraphic and geochronological evidence, the fossil assemblages from Jinyuan Cave can be divided into three successive faunas that span the Late Cenozoic (ca. 3.60–0.35 Ma): the Wanghai fauna from upper faunal unit (Middle Pleistocene, 0.78–0.35 Ma), the Jinyuan fauna from middle-lower faunal unit (Early Pleistocene, 2.60–0.78 Ma) and the Luotuoshan fauna of the bottommost faunal unit (Late Pliocene, 3.6–2.6 Ma). The mammalian faunal evolution of Jinyuan Cave can be divided into four temporal stages during the late Cenozoic. The new discovered Jinyuan Cave provides a unique and nearly-continuous faunal and sedimentary sequence stretching from the Late Pliocene to the Middle Pleistocene, hugely significant for establishing the Quaternary Mammal Fauna Sequence of Northeast China for the first time based on a combination of biostratigraphy, geochronology, and for discussing the environmental background.

Ancient DNA research has developed rapidly over the past few decades due to improvements in PCR and next‐generation sequencing (NGS) technologies, but challenges still exist. One major challenge in relation to ancient DNA research is to recover genuine endogenous ancient DNA sequences from raw sequencing data. This is often difficult due to degradation of ancient DNA and high levels of contamination, especially homologous contamination that has extremely similar genetic background with that of the real ancient DNA. In this study, we collected whole‐genome sequencing (WGS) data from 6 ancient samples to compare different mapping algorithms. To further explore more effective methods to separate endogenous DNA from homologous contaminations, we attempted to recover reads based on ancient DNA specific characteristics of deamination, depurination, and DNA fragmentation with different parameters. We propose a quick and improved pipeline for separating endogenous ancient DNA while simultaneously decreasing homologous contaminations to very low proportions. Our goal in this research was to develop useful recommendations for ancient DNA mapping and for separation of endogenous DNA to facilitate future studies of ancient DNA., Our method for ancient DNA mapping and filtering contamination can decrease the contamination to very low level. We believe that the work we present can facilitate future studies of ancient DNA.

The question of what the ecology communities of the Loess Plateau looked like before the extensive anthropogenic reshaping processes of the late-Holocene has stirred a long debate. A better understanding of these human-induced changes will not only help us understand the extent of paleoeconomic practices, but also inform future conservation actions on this ecologically fragile landscape. This paper presents a systematic study of wood charcoal from a series of archaeological sites, demonstrating that woody plants and woodlands were widely distributed and geographically diverse on the Loess Plateau in response to the East Asian Monsoon. In the Guanzhong Basin, oak ( Quercus spp.) woodlands were associated with a few tropical-subtropical taxa, which changed to oak and pine ( Pinus spp.) mixed forests on the eastern plateau, while on the northern plateau coniferous woodlands were dominant. On the western Loess Plateau, oak and elm ( Ulmus spp.) woodland and spruce ( Picea spp.) forests were widespread. The charcoal results suggest that human impacts on the dominant species might have begun as early as ca. 3500 cal yr BP, with oak replaced by Prunus as the dominant taxon, including many economically significant species, such as peaches ( P. persica) and apricots ( P. armeniaca). Furthermore, the charcoal data show that due to warm and wet climatic conditions in the mid-Holocene, the distribution of tropical-subtropical taxa shifted markedly northwards into the Guanzhong and Tianshui Basins, and the central part of the eastern Loess Plateau, which became characterized by high frequencies of Bamboo.

Wheat and barley evolved from large-seeded annual grasses in the arid, low latitudes of Asia; their spread into higher elevations and northern latitudes involved corresponding evolutionary adaptations in these plants, including traits for frost tolerance and shifts in photoperiod sensitivity. The adaptation of farming populations to these northern latitudes was also a complex and poorly understood process that included changes in cultivation practices and the varieties of crops grown. In this article, we push back the earliest dates for the spread of wheat and barley into northern regions of Asia as well as providing earlier cultural links between East and West Asia. The archaeobotanical, palynological and anthracological data we present come from the Tongtian Cave site in the Altai Mountains, with a punctuated occupation dating between 5,200 and 3,200 calibrated years bp, coinciding with global cooling of the middle–late Holocene transition. These early low-investment agropastoral populations in the north steppe area played a major role in the prehistoric trans-Eurasian exchange. The spread of wheat and barley involves evolutionary and human adaptation but has been difficult to date properly. Findings from a cave site suggest a much earlier transfer of cereal grains across Eurasia.

The nature and dynamics of climate change in central Asia since the late Pleistocene are controversial. Moreover, most of the published studies focus mainly on the evolution of moisture conditions, and there have been few attempts to address changes in seasonality. In this study, records of δ 13Corg, TOC, TN, C/N and grain size were obtained from lacustrine sediments at Yili Basin, Xinjiang, NW China. Our aim was to reconstruct the trend in seasonality of precipitation from the last glaciation to the Holocene. The organic matter content of the sediments is derived predominantly from terrestrial plants. The δ 13Corg values vary from −19.4‰ to −24.8‰, indicating that the vegetation was dominated by C3 plants. Winter-spring precipitation is identified as the factor determining the relative proportions of C3 and C4 plants in the region. A negative trend in δ 13Corg corresponding to an increase in the relative abundance of C3 plants indicate a trend of increasing winter-spring precipitation from the last glaciation to the Holocene. The increased incidence of wintertime storms in the interior of Asia is suggested to result in the increase of winter-spring precipitation in the Holocene.

Supplemental material, Supplementary_material_3 for Forest cover and composition on the Loess Plateau during the Middle to Late-Holocene: Integrating wood charcoal analyses by Hui Shen, Xiaoqiang Li, Robert Spengler, Xinying Zhou and Keliang Zhao in The Holocene

Supplemental material, Supplementary for Water management and wheat yields in ancient China: Carbon isotope discrimination of archaeological wheat grains by Zhou Xinying, Zhu Lin, Robert N Spengler, Zhao Keliang, Liu Junchi, Xu Xing, Bao Yige, John Dodson, Xu Hai and Li Xiaoqiang in The Holocene

We present new pollen data from a drilling core from the North China Plain which illustrate the nature of vegetation evolution in the temperate zone of Asia during an interval containing the Mid-Pleistocene Transition (MPT), ~1.2–0.7 Ma. Results show that, from 1.7–1.2 Ma, closed needle-leaved and broadleaved mixed forest predominated. The most important vegetation change event occurred at 1.2 Ma when there was a decline in coniferous forest and a significant increase in Artemisia, Chenopodiaceae and Poaceae grassland. There was a continued degradation of the regional forest vegetation and its replacement by woody grassland about 0.7 Ma. Patterns of vegetation change correlate closely with the key climate fluctuations of the MPT and coincide with major turnover events of large mammalian fauna (>10 kg) in China. In particular, >50% of large mammalian species became extinct in the course of the forest decline; however, they were replaced by new mammalian species after 0.7 Ma. Comparison of the vegetation and faunal records indicates that the process of forest replacement by grassland in the northern temperate zone during the MPT was associated with an acceleration of the rate of turnover of the large mammalian fauna, in terms of extinction and speciation.

The reconstruction of fruit collection and cultivation based on plant remains plays an important role in understanding the subsistence strategies of ancient societies. Here, we report the identification of fossil charcoal from eight sites in the Hexi Corridor to give a clue to the early exploitation of fruit resources in the period 2300–400 bc. Charcoal assemblages show that millet farmers may have collected some tree fruits including bird cherry (Padus sp.), pear (Pyrus sp.) and whitebeam (Sorbus sp.) in the period 2300–2000 bc. From 2000 to 1500 bc there was continuing utilization of Padus sp., Sorbus sp. and cotoneaster (Cotoneaster sp.), at a time when cereal agriculture of wheat and barley had been introduced from outside. Based on analysis of ecological distribution, reproductive biology and the history of utilization, we infer that these fruits were gathered from the wild rather than cultivated. Later, the cultivation of non-native mulberry (Morus alba) began around 1500 bc in the context of an established high-yield wheat agriculture, probably indicating the earliest sign of horticulture in the Hexi Corridor. As with the beginning of agriculture, the horticulture is associated with cultivation of non-native species. In short, the variations in the presence of charred wood of fruit trees indicate that people might have collected wild fruits over a period of time, and that horticulture occurred much later than the spread of a variety of cereal and other crops in the Hexi Corridor.

Based on identification of fossil charcoals from 11 sites in the Hexi Corridor, we reconstruct the local vegetation community and human impact on it in the period from 4300 to 2400 cal. yr BP. More...

A sediment section retrieved from Luyang Lake, Shaanxi province, China was employed for grain-size, total organic carbon content (TOC) and carbonates (CaCO 3 ) analyses. Based on the Optically Stimulated Luminescence (OSL) chronology, the evolution of Luyang Lake since the last 34,000 years was reconstructed. Then the historical anthropogenic information like populations and arable lands obtained from literature were incorporated into the environmental sequence to demonstrate the linkage of lake evolution with both climatic and anthropogenic forcings. It indicated that the appearance of loessial sediment during ca. 33.4–10.7 ka exhibited a much lower lake level associated with a cold and dry climate setting. The sediment became finer with increasing TOC after ca. 10.7 ka implied the enhanced monsoon rainfall and relatively higher lake level until ca. 4.6 ka. Much higher TOC and lowest CaCO 3 at 7.2–4.6 ka suggested the Holocene Climate Optimum in the region. The rising CaCO 3 and declining TOC at ca. 4.6–2.0 ka revealed the enhanced evaporation/precipitation rate and depressed paleoproductivity, suggesting a drier climate. TOC reached its highest after ca. 2 ka, coinciding with the increasing population and the expanding arable lands since the last 600 years, would suggest the anthropogenic impacts like land reclamation and farming rather than climate forcing. Briefly, the evolution of Luyang Lake was controlled by the monsoon climate through geological times and the intensified anthropogenic interferences since the last 2 ka, especially the last 600 years, would account for the transformation of freshwater lake to a saline lake and wetland environment.

To quantitatively reconstruct Holocene precipitation for particular geographical areas, suitable proxies and faithful dating controls are required. The fossilized seeds of common millet (Panicum miliaceum) are found throughout the sedimentary strata of northern China and are suited to the production of quantitative Holocene precipitation reconstructions: their isotopic carbon composition (δ13C) gives a measure of the precipitation required during the growing season of summer (here the interval from mid-June to September) and allows these seeds to be dated. We therefore used a regression function, as part of a systematic study of the δ13C of common millet, to produce a quantitative reconstruction of mid-Holocene summer precipitation in the Guanzhong Basin (107°40′–107°49′ E, 33°39′–34°45′ N). Our results showed that mean summer precipitation at 7.7–3.4 ka BP was 353 mm, ∼ 50 mm or 17 % higher than present levels, and the variability increased, especially after 5.2 ka BP. Maximum mean summer precipitation peaked at 414 mm during the period 6.1–5.5 ka BP, ∼ 109 mm (or 36 %) higher than today, indicating that the East Asian summer monsoon (EASM) peaked at this time. This work can provide a new proxy for further research into continuous paleoprecipitation sequences and the variability of summer precipitation, which will promote the further research into the relation between early human activity and environmental change.

We reconstructed paleovegetation changes on the Chinese Loess Plateau by applying concepts in palynology and pollination biology to the statistical analysis of the size of Artemisia pollen grains from 26 surface samples, four loess paleosoil profiles, and extant Artemisia species. We found that the size of Artemisia pollen grains varied in different plant communities, and was positively correlated with local habitat quality and population density of local Artemisia communities. The Mean Artemisia Pollen Size (MAPS), which has changed significantly since Marine Isotope Stage 3 (MIS3), reflects integrated ecological changes, including compositional changes and shifts in population density. During MIS3, the high MAPS values indicate that high population densities of Artemisia grassland covered the northern and southern Loess Plateau. During the Last Glacial Maximum (LGM), with much less favorable growing conditions, a low MAPS value indicates that lower-density short grass steppe covered the Loess Plateau at that time. Overall, the results demonstrate that a statistical analysis of the size of fossil pollen grains at genus level can provide useful ecological information, e.g., on changes in the composition and population density of local communities, and thus can lead to a better understanding of the evolution of terrestrial ecosystems.