Phytolith remains of rice (Oryza sativa L.) recovered from the Shangshan site in the Lower Yangtze of China have previously been recognized as the earliest examples of rice cultivation. However, ...because of the poor preservation of macroplant fossils, many radiocarbon dates were derived from undifferentiated organic materials in pottery sherds. These materials remain a source of debate because of potential contamination by old carbon. Direct dating of the rice remains might serve to clarify their age. Here, we first validate the reliability of phytolith dating in the study region through a comparison with dates obtained from other material from the same layer or context. Our phytolith data indicate that rice remains retrieved from early stages of the Shangshan and Hehuashan sites have ages of approximately 9,400 and 9,000 calibrated years before the present, respectively. The morphology of rice bulliform phytoliths indicates they are closer to modern domesticated species than to wild species, suggesting that rice domestication may have begun at Shangshan during the beginning of the Holocene.
Compared with the monistic structure of crop agriculture in Southwest Asia and Mesoamerica, agriculture in ancient China reflects the characteristics of a dualistic structure with millet in the north ...and rice in the south. It is argued that the rice and millet farming modes were mutually exchanged during their development and formed a vast region of mixed farming. However, the time and place of its origin, the routes of dissemination, and the development patterns and possible influence factors of mixed farming remain unclear. This study systematically collected information from 804 sites with millet and rice records and detailed floatation results from 78 mixed farming sites in prehistoric China. Three north–south communication corridors are identified between the upper, middle and lower Yellow and Yangtze River Valleys that began around 5500 BP, 8400 BP and 4600 BP, respectively. Cultural communication accompanied by human migration and the unique natural environment of loess and East Asia monsoons facilitated the interaction between millet and rice farming through these corridors. As a comprehensive reflection of the interaction between millet and rice farming, the crop structure of the four core mixed farming regions is in a continual process of adjustment, with the selection of foxtail millet in the southward spread of millet agriculture and temperate Oryza japonica in the northern spread of rice agriculture.
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•We report one concept for synthesis of atomically dispersed RuO2-graphene quantum dot-graphene.•Ultrasmall RuO2 was atomically dispersed on graphene sheets with a very high Ru ...loading of 4.2%•The intimate contacts achieve to formation of double Schottky heterojunctions at the interfaces.•Ru in hybrid brings an increased capacitance of more than five times of the theoretical value of RuO2.•The study offers one way for synthesis of graphene-based composites with high catalytic activity.
Poor capacity and cycle stability limit many applications of supercapacitors in wearable electronic devices. The study reports synthesis of atomically dispersed RuO2 (AD-RuO2)-tryptophan functionalized graphene quantum dot (Trp-GQD)-graphene (G) hybrid. Trp-GQD was bound to graphene oxide (GO) by π-π stacking and then combined with Ru3+ ion via Ru-N coordination bond to form Ru-Trp-GQD-GO complex. Followed by partial reduction into graphene gel with hydrazine hydrate, thermal reduction in N2 and oxidation in air in sequence. The resulting AD-RuO2-Trp-GQD-G offers well-defined three-dimensional structure and high Ru loading of 4.2%. RuO2 was atomically dispersed on the graphene sheets. The intimate contacts of Trp-GQD with G and RuO2 create the double Schottky heterojunctions at the interfaces and results in an excellent catalytic activity. The AD-RuO2-Trp-GQD-G electrode exhibits high capacitance of 503.7F g−1 at 1 A g−1. The value is much higher than that of graphene electrode (160F g−1) and G-Trp-GQD electrode (192F g−1). This verifies that the introduction of Ru per gram can bring an increased capacitance of 7421.4F, which is more than five times of the theoretical value of RuO2 electrode. The flexible supercapacitor displays high capacitance (354F g−1 at 0.5 A g−1), rate-capacity (186F g−1 at 20 A g−1) and cycling stability (99.6% capacity retention after 10,000 cycles at 10 A g−1). The supercapacitor is able to deliver a power density of up to 52000 W kg−1 and energy density of up to 332 Wh Kg−1 and good application prospect in wearable electronic devices.
Historic human–climate interactions have been of interest to scholars for a long time. However, exploring the long-term relation between prehistoric demography and climate change remains challenging ...because of the absence of an effective proxy for population reconstruction. Recently, the summed probability distribution of archaeological radiocarbon dates has been widely used as a proxy for human population levels, although researchers recognize that such usage must be cautious. This approach is rarely applied in China due to the lack of a comprehensive archaeological radiocarbon database, and thus the relation between human population and climate change in China remains ambiguous. Herein we systematically compile an archaeological 14C database (n = 4656) for China for the first time. Using the summed probability distributions of the radiocarbon dates alongside high-resolution palaeoclimatic records, we show that: 1) the commencement of major population expansion in China was at 9 ka cal BP, occurring after the appearance of agriculture and associated with the early Holocene climate amelioration; 2) the major periods of small population size and population decline, i.e., 46–43 ka cal BP, 41–38 ka cal BP, 31–28.6 ka cal BP, 25–23.5 ka cal BP, 18–15.2 ka cal BP, and 13–11.4 ka cal BP, correspond well with the dating of abrupt cold events in the Last Glacial (LG) such as the Heinrich and Younger Dryas (YD) events, while the major periods of high-level population in the Holocene, i.e., 8.5–7 ka cal BP, 6.5–5 ka cal BP and 4.3–2.8 ka cal BP, occur at the same times as warm-moist conditions and Neolithic cultural prosperity, suggesting that abrupt cooling in the climate profoundly limited population size and that mild climate episodes spurred a growth in prehistoric populations and advances in human cultures; and 3) populations in different regions experience different growth trajectories and that their responses to climate change are varied, due to both regional environmental diversity and the attainment of different levels of adaptive strategies.
•A comprehensive archaeological 14C database from China.•The commencement of major population expansion in China was at 9 ka cal BP.•New insights into the relation between climate change and population size.•Diverse demographic trajectories and various responses to climate change by region.
The in-situ formation, fixation and structural control of metal nanoparticles on graphene sheets are crucial issue to fabricate metal-graphene composite with high electrochemical performance. The ...study reports the synthesis of superparamagnetic NiCo-graphene quantum dot-graphene composite (NiCo-GQD-G). Histidine-functionalized graphene quantum dots (GQDs) were immobilized on graphene sheets of graphite oxide (GO) to form GQD-GO hybrid via π-π stacking. The hybrid are combined with Ni2+ and Co2+ to produce NiCo-GQD-GO complex. Followed by thermal reduction and partial oxidation. The resulting NiCo-GQD-G has a well-defined three-dimensional structure, monodispersity and superparamagnetic. NiCo nanocrystals were covered by NiO and CoO to produce core-shell structure with average particle size of 7.2 nm. The nanostructure can be effectively adjusted by varying the mass ratios of GQD/GO and NiCo/GO. The unique architecture promotes enhanced electron/ion conductivity, catalytic activity and magnetofluid property. The NiCo-GQD-G was adsorbed on nickel foam by magnet to make an electrode without any binder and conductive agent. The electrode exhibits high capacity (1808 F g−1 at 1 A g−1), rate-capacity (1525 F g−1 at 10 A g−1 and 900 F g−1 at 200 A g−1) and cycling stability (99.2% of capacity retention after 5000 cycles at 10 A g−1) in 3.0 M KOH electrolyte. The flow hybrid supercapacitor provides energy density of 247.4 W h kg−1 at power density of 6596 W kg−1 and 111.2 W h kg−1 at power density of 160100 W kg−1. The synthesis can be also used for construction of other metal-graphene composites with excellent dispersion and controllable nanostructure.
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•We reported one concept for synthesis of NiCo-graphene quantum dot-graphene hybrid.•The hybrid offers excellent 3D structure, monodispersity and superparamagnetic.•The hybrid show high electron/ion conductivity, catalytic activity and magnetofluid.•The hybrid exhibits high specific capacitance, rate-capacity and cycling stability.•The flow supercapacitor based on hybrid gives high energy density and power density.
There is a prevalence of multiagent reinforcement learning (MARL) methods that engage in centralized training. These methods rely on all the agents sharing various types of information, such as their ...actions or gradients, with a centralized trainer or each other during the learning. Subsequently, the methods produce agent policies whose prescriptions and performance are contingent on other agents engaging in behavior assumed by the centralized training. But, in many contexts, such as mixed or adversarial settings, this assumption may not be feasible. In this article, we present a new line of methods that relaxes this assumption and engages in decentralized training resulting in the agent’s individual policy. The interactive advantage actor-critic (IA2C) maintains and updates beliefs over other agents’ candidate behaviors based on (noisy) observations, thus enabling learning at the agent’s own level. We also address MARL’s prohibitive curse of dimensionality due to the presence of many agents in the system. Under assumptions of action anonymity and population homogeneity, often exhibited in practice, large numbers of other agents can be modeled aggregately by the count vectors of their actions instead of individual agent models. More importantly, we may model the distribution of these vectors and its update using the Dirichlet-multinomial model, which offers an elegant way to scale IA2C to many-agent systems. We evaluate the performance of the fully decentralized IA2C along with other known baselines on a novel Organization domain, which we introduce, and on instances of two existing domains. Experimental comparisons with prominent and recent baselines show that IA2C is more sample efficient, more robust to noise, and can scale to learning in systems with up to a hundred agents.
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.
•Providing a successive rice domestication process during the Holocene at a sediment core in the Ningshao Plain, the lower Yangtze.•The beginning of rice domestication in the Ningshao Plain was as early as 9,600 cal. yr BP.•Rice domestication was a protracted transition lasting over 3,500 years due to the influence of the marine transgression.
The eastern coastal zone of China is densely populated and widely recognized as a center of rice domestication, which has undergone dramatic sea-level fluctuation during the Holocene epoch. Hemudu ...culture is distributed mainly in the eastern coastal area and was once presumed as a mature agricultural economy based on rice, making it an ideal case for examining the remarkable human-environment interaction in the Lower Yangtze River. Though numerous studies have been conducted on the cultural evolution, ecological environment, and rice domestication of Hemudu culture, the impact of sea-level fluctuation on human settlement and food production remains controversial. In this study, we report high-resolution pollen, phytolith, and diatom records, and accurately measured elevation from the Yushan site, which is the closest site of Hemudu culture to the modern coastline. Based on the data gathered, we suggest that the Hemudu culture and subsequent Liangzhu culture developed in the context of regression and were interrupted by two transgressions that occurred during 6300-5600 BP and 5000-4500 BP. The regional ecological environment of the Yushan site alternated between intertidal mudflat and freshwater wetlands induced by sea-level fluctuations in the mid-late Holocene. Though rice was cultivated in the wetland as early as 6700 BP, this cultivation was subsequently discontinued due to the transgression; thus, full domestication of rice did not occur until 5600 BP in this region. Comprehensive analysis of multiple proxies in this study promote the understanding of the relationship between environmental evolution, cultural interruption, and rice domestication.
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•Hemudu and succedent Liangzhu culture were interrupted by marine transgressions.•Environmental alteration between intertidal mudflat and freshwater wetlands.•Full domestication of rice was protracted until 5600 BP•Dynamic interaction between sea level, cultural interruption and rice domestication.
The response of population and agriculture to abrupt climate events remains a matter of heated debates, especially the societal collapses related to the 4.2 ka event. Long-term interaction between ...regional demography and millet-rice agriculture in China provide a unique opportunity to study this issue. Here using a newly database of radiocarbon dates and archaeobotanical data spanning the Neolithic-Bronze Age from different regions in China, we address the response and resilience of demography and agriculture to the 4.2 ka event. Regional populations show an antipodal pattern of boom in north and northwest (NW) and bust in south and southeast (SE) China during 4300–3500 cal a BP. This pattern coincided with the prosperity and breakdown of millet and rice agricultures contemporaneously, respectively. Our study reveals that drought-induced enlargement of farmland and trans-Eurasian cultural exchange promoted the sustainability of millet agriculture and population in NW China, and combined effects of cooling and flooding events and social crises caused a decline in rice agriculture and population in SE China. The diverse response and resilience of human societies to the 4.2 ka event has been attributed to both climatic anomalies and cultural exchange across different regions. In sum, the complex societies with high stratification and hierarchies were more vulnerable to abrupt climate events than low stratified societies open to exchanges during the middle to late Holocene.
•High-resolution and quantitative proxies of population and agriculture were present.•Antipodal pattern of boom in NW and bust in SE China during the 4.2 ka event.•Diverse resilience was attributed to both climatic anomalies and cultural exchange.•High stratified society was more vulnerable to climate events than open society.
Legumes and cereals, which provide different nutrients, are cultivated as coupled crops in most centers of plant domestication worldwide. However, as the only legume domesticated in China, the ...spatio-temporal distribution of soybeans and its status in the millet- and rice-based agricultural system of the Neolithic and Bronze Ages remains elusive. Here, archaeobotanical evidence of soybeans (n=254), millet (n=462), rice (n=482), and zooarchaeological evidence of fish (n=138) were synthesized to elucidate the phenomenon of coupled or decoupled cereals and legumes in prehistoric China. During the Neolithic and Bronze Ages, soybeans was mostly confined to northern China and rarely found in southern China, serving as a companion to millet. In contrast, fish remains have been widely found in southern China, indicating a continuous reliance on fish as a staple food besides rice. Thus, an antipodal pattern of millet-soybeans and rice-fish agricultural systems may have been established in northern and southern China since the late Yangshao period (6000–5000 cal BP) respectively. These two agricultural systems were not only complementary in terms of diet, but they also exhibited positive interactions and feedback in the coculture system. Consequently, these two systems enabled the sustainable intensification of agriculture and served as the basis for the emergence of complex societies and early states in the Yellow and Yangtze Rivers.
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