Exploring prehistoric variation in human–environmental interaction is critical for understanding the historical patterns and mechanisms of long-term human–land evolution. In this paper we review the ...published radiocarbon and optically stimulated luminescence (OSL) data from Late Paleolithic, Neolithic and Bronze Age sites in China, analyze the spatial–temporal distribution of these sites, and compare it with the results of recent paleoclimatic and archaeological studies. We seek to study the trajectory and influencing factors of human–environmental interactions in late prehistoric China. We detect changing patterns in the relationship between humans and the environment during different phases of the prehistoric era in China. Climate change clearly affected the environment of hunter-gatherer groups between 50,000–10,000 BP (before present, defined as 1950AD), and variation in human population in Neolithic China (∼10,000–4000 BP) was likely influenced primarily by the development of agriculture, in addition to substantial climate events. The spatial scale of human settlements expanded in the Bronze Age (∼4000–2200 BP) in a period of cooling climate. During this time the impact of human activities on the environment increased significantly, primarily caused by technological innovations related to the onset of prehistoric transcontinental cultural exchange in Eurasia.
A late Middle Pleistocene mandible from Baishiya Karst Cave (BKC) on the Tibetan Plateau has been inferred to be from a Denisovan, an Asian hominin related to Neanderthals, on the basis of an amino ...acid substitution in its collagen. Here we describe the stratigraphy, chronology, and mitochondrial DNA extracted from the sediments in BKC. We recover Denisovan mitochondrial DNA from sediments deposited ~100 thousand and ~60 thousand years ago (ka) and possibly as recently as ~45 ka. The long-term occupation of BKC by Denisovans suggests that they may have adapted to life at high altitudes and may have contributed such adaptations to modern humans on the Tibetan Plateau.
Denisovans are members of a hominin group who are currently only known directly from fragmentary fossils, the genomes of which have been studied from a single site, Denisova Cave
in Siberia. They are ...also known indirectly from their genetic legacy through gene flow into several low-altitude East Asian populations
and high-altitude modern Tibetans
. The lack of morphologically informative Denisovan fossils hinders our ability to connect geographically and temporally dispersed fossil hominins from Asia and to understand in a coherent manner their relation to recent Asian populations. This includes understanding the genetic adaptation of humans to the high-altitude Tibetan Plateau
, which was inherited from the Denisovans. Here we report a Denisovan mandible, identified by ancient protein analysis
, found on the Tibetan Plateau in Baishiya Karst Cave, Xiahe, Gansu, China. We determine the mandible to be at least 160 thousand years old through U-series dating of an adhering carbonate matrix. The Xiahe specimen provides direct evidence of the Denisovans outside the Altai Mountains and its analysis unique insights into Denisovan mandibular and dental morphology. Our results indicate that archaic hominins occupied the Tibetan Plateau in the Middle Pleistocene epoch and successfully adapted to high-altitude hypoxic environments long before the regional arrival of modern Homo sapiens.
DFT calculations have been performed to gain insight into the mechanism of formic acid (HCOOH) decomposition into H2 and CO2, catalyzed by a well-defined bifunctional cyclometalated iridium(III) ...complex (a Ir–H hydride) based on a 2-aryl imidazoline ligand with a remote NH functionality. It is shown that the reaction features the direct protonation of the Ir–H hydride by HCOOH with the hydrogen shuttling between the NH group and the carbonyl group of HCOOH. Importantly, the simultaneous presence of two HCOOH molecules is proposed to be important for the dehydrogenation, where one works as a hydrogen source and the other acts as a hydrogen shuttle to assist the long-range intermolecular hydrogen migration. The dehydrogenation mechanism is referred to as HCOOH self-assisted concerted hydrogen migration. With such a mechanism, the energetic span, i.e. the apparent activation energy of the catalytic cycle, is calculated to be 17.3 kcal/mol, which is consistent with the observed rapid dehydrogenation of HCOOH under mild conditions (40 °C). On one hand, the effectiveness of the self-assisted catalytic system is attributed to the d–pπ conjugation between the Ir center and the proximal nitrogen, which increases the electron density at the Ir center and hence promotes the Ir–H bond cleavage. On the other hand, the effectiveness is also closely related to the hydrogen-shared three-center–four-electron (3c-4e) bond between formate and formic acid, which stabilizes the transition states and hence reduces the free energy barriers of the reaction. In addition, calculated results also emphasize the importance of the concerted catalysis of the bifunctional catalyst: when the γ-NH functional group does not participate in the reaction or is replaced by an O atom, the reaction becomes remarkably less favorable. The present work rationalizes the experimental findings and provides important insights into understanding the catalysis of the bifunctional cyclometalated iridium(III) complexes.
Past human genetic diversity and migration between southern China and Southeast Asia have not been well characterized, in part due to poor preservation of ancient DNA in hot and humid regions. We ...sequenced 31 ancient genomes from southern China (Guangxi and Fujian), including two ∼12,000- to 10,000-year-old individuals representing the oldest humans sequenced from southern China. We discovered a deeply diverged East Asian ancestry in the Guangxi region that persisted until at least 6,000 years ago. We found that ∼9,000- to 6,000-year-old Guangxi populations were a mixture of local ancestry, southern ancestry previously sampled in Fujian, and deep Asian ancestry related to Southeast Asian Hòabìnhian hunter-gatherers, showing broad admixture in the region predating the appearance of farming. Historical Guangxi populations dating to ∼1,500 to 500 years ago are closely related to Tai-Kadai and Hmong-Mien speakers. Our results show heavy interactions among three distinct ancestries at the crossroads of East and Southeast Asia.
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•Guangxi region in southern China had distinct East Asian ancestry 11 kya not found today•At least three distinct ancestries were in southern China and SE Asia prior to 10 kya•Three admixed ancestries were present in pre-agricultural Guangxi 9–6 kya•Tai-Kadai- and Hmong-Mien-related ancestry present in Guangxi by 1.5–0.5 kya
Genome-wide analysis of 31 ancient individuals from southern China (Guangxi and Fujian) reveals human population history at the crossroads of East and Southeast Asia from 500–11,000 years ago.
While the catalytic conversion of glucose to 5-hydroxymethyl furfural (HMF) catalyzed by SO3H-functioned ionic liquids (ILs) has been achieved successfully, the relevant molecular mechanism is still ...not understood well. Choosing 1-butyl-3-methylimidazolium chloride C4SO3HmimCl as a representative of SO3H-functioned IL, this work presents a density functional theory (DFT) study on the catalytic mechanism for conversion of glucose into HMF. It is found that the conversion may proceed via two potential pathways and that throughout most of elementary steps, the cation of the IL plays a substantial role, functioning as a proton shuttle to promote the reaction. The chloride anion interacts with the substrate and the acidic proton in the imidazolium ring via H-bonding, as well as provides a polar environment together with the imidazolium cation to stabilize intermediates and transition states. The calculated overall barriers of the catalytic conversion along two potential pathways are 32.9 and 31.0 kcal/mol, respectively, which are compatible with the observed catalytic performance of the IL under mild conditions (100 °C). The present results provide help for rationalizing the effective conversion of glucose to HMF catalyzed by SO3H-functionalized ILs and for designing IL catalysts used in biomass conversion chemistry.
Prehistoric human history on the Tibetan Plateau is a hotly debated topic. Archaeological research on the plateau during the past few decades has enormously improved our understanding of the topic ...and makes it possible for us to consider the processes and mechanisms of prehistoric human migration to the region. By reviewing the published archaeological research on the Tibetan Plateau, we propose that the first people on the plateau initially spread into the He-Huang region from the Chinese Loess Plateau, and then moved to the low elevation Northeastern Tibetan Plateau and perhaps subsequently to the entire plateau. This process consisted of four stages. （1） During the climatic amelioration of the Last Deglacial period （15-11.6 ka BP）, Upper Paleolithic hunter-gatherers with a developed microlithic technology first spread into the Northeastern Tibetan Plateau. （2） In the early-mid Holocene （11.6-6 ka BP）, Epipaleolithic microlithic hunter-gatherers were widely distributed on the northeastern plateau and spread southwards to the interior plateau, possibly with millet agriculture developed in the neigh- boring low elevation regions. （3） In the mid-late Holocene （6-4 ka BP）, Neolithic millet farmers spread into low elevation river valleys in the northeastern and southeastern plateau areas. （4） In the late Holocene （4-2.3 ka BP）, Bronze Age barley and wheat farmers further settled on the high elevation regions of the Tibetan Plateau, especially after 3.6 ka BP. Finally, we sug- gest that all of the reported Paleolithic sites earlier than the LGM on the Tibetan Plateau need further examination.
The excited states of polyatomic systems are rather complex, and often exhibit meta-stable dynamical behaviors. Static analysis of reaction pathway often fails to sufficiently characterize excited ...state motions due to their highly non-equilibrium nature. Here, we proposed a time series guided clustering algorithm to generate most relevant meta-stable patterns directly from ab initio dynamic trajectories. Based on the knowledge of these meta-stable patterns, we suggested an interpolation scheme with only a concrete and finite set of known patterns to accurately predict the ground and excited state properties of the entire dynamics trajectories, namely, the prediction with ensemble models (PEM). As illustrated with the example of sinapic acids, The PEM method does not require any training data beyond the clustering algorithm, and the estimation error for both ground and excited state is very close, which indicates one could predict the ground and excited state molecular properties with similar accuracy. These results may provide us some insights to construct molecular mechanism models with compatible energy terms as traditional force fields.
By performing density functional theory calculations, we have studied the CO pathway and non-CO pathway of methanol oxidation on the PtAu(111) bimetallic surface. CO is shown to possess larger ...adsorption energy on the PtAu(111) surface than that on the pure Pt(111) surface, and the non-CO pathway on the bimetallic surface is found to be energetically more favorable than the CO pathway. These calculated results propose that the improved electrocatalytic activity of PtAu bimetallic catalysts for methanol oxidation should be attributed to the alternation in the major reaction pathway from the CO pathway on the pure Pt surface to the non-CO pathway on the PtAu bimetallic surface rather than the easier removal of CO on PtAu catalysts than on pure Pt catalysts.
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