Shimao City is considered an important political and religious center during the Late Neolithic Longshan period of the Middle Yellow River basin. The genetic history and population dynamics among the Shimao and other ancient populations, especially the Taosi-related populations, remain unknown. Here, we sequenced 172 complete mitochondrial genomes, ranging from the Yangshao to Longshan period, from individuals related to the Shimao culture in northern Shaanxi Province and Taosi culture in southern Shanxi Province, Middle Yellow River basin. Our results show that the populations inhabiting Shimao City had close genetic connections with an earlier population in the Middle Neolithic Yangshao period of northern Shaanxi Province, revealing a mostly local origin for the Shimao Society. In addition, among the populations in other regions of the Yellow River basin, the Shimao-related populations had the closest maternal affinity with the contemporaneous Taosi populations from the Longshan period. The Shimao-related populations also shared more affinity with present-day northern Han populations than with the minorities and southern Han in China. Our study provides a new perspective on the genetic origins and structure of the Shimao people and the population dynamics in the Middle Yellow River basin during the Neolithic period.

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Ancient Mitogenomes Reveal the Origins and Genetic Structure of the Neolithic Shimao Population in Northern China

Societal Impact Statement Combining natural and social science approaches to conduct archeological research on wooden cultural relics is important for exploring major aspects of ancient civilizations. The Forbidden City in Beijing, China, is the largest existing wooden palace complex in the world. We examined ancient DNA of imperial wood “Nanmu” specimens taken from representative structural components of the Forbidden City, in order to provide a new perspective on the long-standing dispute about its species. This allowed us to accurately identify and properly restore these wooden artifacts and improved our understanding of the past interactions between plant distribution, forest resources, and human activities. Summary Exploring the life styles and production methods of past generations using plant resources can help us to improve our understanding of human civilization. Nanmu, known for its high wood quality, was exclusively used for imperial palace construction in the 15th–19th centuries in China, yet its species has been a subject of long-standing debate. Here, we revisit this unresolved problem, using morphology and ancient DNA (aDNA) to analyze 21 centuries-old Nanmu specimens sampled from representative palaces of the Forbidden City. Cytochemical staining demonstrated that endogenous aDNA sporadically occurs in the wood ray parenchyma cells of Nanmu specimens. High-quality plastid genomes were retrieved from archeological woods for the first time via an aDNA capture method, with 90%–100% coverage (137,663–152,805 bp) and sequence depths of 27.05- to 1409.94-fold. Utilizing these ancient genomes, our results demonstrate that Phoebe zhennan and Phoebe hui are most likely the main species of Nanmu in the Forbidden City. This finding diverges from the prevailing view that Nanmu encompasses woods from the whole genus Phoebe and even its close relative Machilus. It also shows that stringent criteria were used when selecting construction materials for the Forbidden City. By combining morphological traits with aDNA analyses, we provide a new solution for identifying the species of timber used for ancient architecture, and we increase our understanding of the way in which forest resources were recognized and utilized by our ancestors despite the lack of a plant taxonomic framework in ancient times. 

Ancient plastid genomes solve the tree species mystery of the imperial wood “Nanmu” in the Forbidden City, the largest existing wooden palace complex in the world

Maternal genetic structure of a neolithic population of the Yangshao culture.

Maternal genetic history of southern East Asians over the past 12,000 years.

The authors achieve a twofold increase in the loading rate of the rare ${}^{39}$Ar in a magneto-optical trap by optically enhancing the metastable production in a plasma source. The result constitutes a significant advance for the use of ${}^{39}$Ar in earth science applications, such as dating alpine ice cores and mapping ocean currents. 

/pdf/optically-enhanced-discharge-excitation-and-trapping-of-mml-3oeuoc8c.pdf

Optically enhanced discharge excitation and trapping of 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Ar</mml:mi><mml:mprescripts /><mml:none /><mml:mn>39</mml:mn></mml:mmultiscripts></mml:math>

Archaeological and ancient DNA studies revealed that Shandong, a multi-culture center in northern coastal China, was home to ancient populations having ancestry related to both northern and southern East Asian populations. However, the limited temporal and geographical range of previous studies have been insufficient to describe the population history of this region in greater detail. Here, we report the analysis of 86 complete mitochondrial genomes from the remains of 9500 to 1800-year-old humans from 12 archaeological sites across Shandong. For samples older than 4600 years before present (BP), we found haplogroups D4, D5, B4c1, and B5b2, which are observed in present-day northern and southern East Asians. For samples younger than 4600 BP, haplogroups C (C7a1 and C7b), M9 (M9a1), and F (F1a1, F2a, and F4a1) begin to appear, indicating changes in the Shandong maternal genetic structure starting from the beginning of the Longshan cultural period. Within Shandong, the genetic exchange is possible between the coastal and inland regions after 3100 BP. We also discovered the B5b2 lineage in Shandong populations, with the oldest Bianbian individual likely related to the ancestors of some East Asians and North Asians. By reconstructing a maternal genetic structure of Shandong populations, we provide greater resolution of the population dynamics of the northern coastal East Asia over the past nine thousand years.

Maternal genetic structure in ancient Shandong between 9500 and 1800 years ago

An isotope enrichment system for 39Ar has been developed at the Institute of Modern Physics, which is designed to increase the abundance of 39Ar in the incident sample gas. With intense Ar+ beams produced by a 2.45 GHz electron cyclotron resonance ion source and a high mass resolution spectrometer system, Ar isotopes are evidently separated on the target plane and selectively collected by an Al target. The separated Ar isotopes have been identified on the target plane, which is consistent with the simulations. According to the recent cross-checked results with atom trap trace analysis, a high enrichment factor of 39Ar has been successfully achieved. This paper will present the design and test results of this system.

An electromagnetic separation system for the enrichment of 39Ar.

The design of a 180° electromagnetic isotope separator with inhomogeneous magnetic field is presented. The optical properties of axially symmetric inhomogeneous sector magnetic field are analyzed in first-order approximation and basic parameters of the separation magnet are determined. A separation magnet with the required optical properties and mass dispersion is designed and the magnetic field distribution also is calculated. The transmission of molybdenum isotopes beam in the designed separator is simulated with Particle-In-Cell (PIC) codes by using three-dimensional (3D) magnetic field. A comparison of the simulation results with the theoretical calculations is presented.

Design of a 180° electromagnetic isotope separator with inhomogeneous magnetic field

A very compact permanent magnet 2.45 GHz electron cyclotron resonance ion source has been designed and developed for various purposes. The microwave power is coupled into the plasma chamber using the coaxial antenna instead of the waveguide, the magnetic field is produced by two NdFeB permanent magnet rings, and the diameter of the source body is only 10 cm. The beam current under different conditions was measured. A maximum of 5.8 mA H+/H2+/H3+ mixed beam could be extracted from a 5.5 mm diameter extraction aperture.

J. L. Liu

Papers

Maternal genetic structure in ancient Shandong between 9500 and 1800 years ago

Maternal genetic structure of a neolithic population of the Yangshao culture.

An electromagnetic separation system for the enrichment of 39Ar.

Design of a 180° electromagnetic isotope separator with inhomogeneous magnetic field

Ion beam production with an antenna type 2.45 GHz electron cyclotron resonance ion source.