Revised dating of the Liujiang skeleton renews understanding of human occupation of China

The emergence of Homo sapiens in Eastern Asia has long been a subject of intense research interest, with the scarcity of well-preserved and dated human fossils posing significant challenges.

Tongtianyan cave, located in the Liujiang District of Liuzhou City, Southern China, has been a focal point of this research, housing one of the most significant fossil finds of Homo sapiens. However, the age of the fossils found within has been a matter of debate -- until now.

In a new international study in Nature Communications, with contributions by Griffith University, researchers have provided new age estimates and revised provenance information for the Liujiang human fossils, shedding light on the presence of Homo sapiens in the region.

Using advanced dating techniques including U-series dating on human fossils, and radiocarbon and optically stimulated luminescence dating on fossil-bearing sediments, the study revealed new ages ranging from approximately 33,000 to 23,000 years ago. Previously, studies had reported ages of up to 227,000 years of age for the skeleton.

"These revised age estimates align with dates from other human fossils in northern China, suggesting a geographically widespread presence of H. sapiens across Eastern Asia after 40,000 years ago," said Professor Michael Petraglia, study co-author and Director of Griffith's Australian Research Centre for Human Evolution.

Dr Junyi Ge, of the Chinese Academy of Sciences, and lead author of the study, said: "This finding holds significant implications for understanding human dispersals and adaptations in the region. It challenges previous interpretations and provides insights into the occupation history of China."

The Liujiang skeletal remains, discovered in 1958, have long been considered among the most significant human fossils from Eastern Asia.

With their excellent preservation, the cranial, dental, and postcranial remains have been the subjects of extensive biological and morphological comparisons across Eurasia.

Dr Qingfeng Shao, of the Nanjing Normal University added: "The findings of this study overturn earlier age estimates and palaeoanthropological interpretations, emphasising the need for robust dating methods and proper provenance documentation in the study of human evolution."

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Causes of the Qing Dynasty's collapse: Parallels to today's instability

The Qing Dynasty in China, after over 250 years, crumbled in 1912. Led by the Complexity Science Hub (CSH), an international research team has pinpointed key reasons behind the collapse, revealing parallels to modern instability and offering vital lessons for the future.

China is considered today to be the world's largest economy (in terms of PPP). However, this position is not new. In 1820, China's economy already held the top spot, accounting for 32.9% of the global GDP. In the interim, there was a period of decline followed by a resurgence. In 1912, after over 250 years in power, the Qing Dynasty collapsed despite being considerably wealthier at the time than modern-day China. "This clearly demonstrates that any economy must be vigilant as circumstances can change, and sometimes rather rapidly," emphasizes Georg Orlandi, the study's first author.

SIMILAR ROOTS THEN AND NOW

"It's crucial to comprehend the origins of such instabilities. Assuming it's a thing of the past and can't recur would be a mistake. Such changes can indeed happen because the underlying mechanisms bear surprising similarities," CSH researcher Peter Turchin points out.

Scientists have been attempting to pinpoint the causes behind the fall of the Qing Dynasty for two centuries. Various factors had previously been proposed, including environmental disasters, foreign incursions, famines, or uprisings. However, "none of these factors provides a comprehensive explanation," notes Turchin.

THREE MAIN DRIVERS

Hence, in this study, researchers amalgamated various factors and discovered that three elements dramatically heightened socio-political pressures:

Firstly, there was a fourfold population explosion between 1700 and 1840. This resulted in reduced land per capita and caused an impoverishment of the rural populace.

Secondly, this led to increased competition for elite positions. While the number of contenders soared, the number of awarded highest academic degrees declined, reaching its nadir in 1796. Because such a degree was necessary for obtaining a position in the powerful Chinese bureaucracy, this mismatch between the number of positions and those desiring them created a large pool of disgruntled elite aspirants. The leaders of the Taiping Rebellion, perhaps the bloodiest civil war in human history, were all such failed elite-wannabes.

Thirdly, the state's financial burden escalated due to rising costs associated with suppressing unrest, declining per capita productivity, and mounting trade deficits stemming from depleting silver reserves and opium imports.

Collectively, these factors culminated in a series of uprisings that heralded the end of the Qing Dynasty and exacted a heavy toll in terms of Chinese lives lost.

THE QING WERE AWARE

According to the study's findings, social tensions had already peaked between 1840 and 1890. "Assuming that the Qing rulers were unaware of this mounting pressure would be erroneous," explains Turchin. The fact that the dynasty endured until 1912 rather underscores its institutional structures' robustness.

However, many of their attempted solutions proved short-sighted or inadequate to the task; for instance, the government raised the allowable quota for people passing certain degree exams but without increasing the number of available openings. This ended up exacerbating the already-building tensions. With the arrival of potent geopolitical challengers through the late 19th century, the rulers ultimately couldn't avert their downfall.

PREVENT INSTABILITY TODAY

We can draw valuable lessons from this historical process for the contemporary era and the future. Many nations worldwide are grappling with potential instability and conditions that closely resemble those of the Qing Dynasty. For instance, competition for top positions remains exceedingly fierce. Orlandi cautions, "When a large number of individuals vie for a limited number of positions, political decision-makers should view this as a red flag, as it can, at the very least, lead to heightened instability."

"Unfortunately, the corrosive impact of rising inequality and diminishing opportunities develop over longer time scales that make them hard to recognize," adds co-author and CSH Affiliated Researcher Daniel Hoyer, "let alone effectively combat within the short political cycles we see in many countries. Without long-term vision and targeted strategies to relieve these social pressures, many places are at risk of going the way of the Qing."

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An early warning system for joint heat and ozone extremes in China

High temperatures exacerbate ground-level ozone production, resulting in a deadly combination of extreme heat and poor air quality that is especially dangerous for children, seniors, and people suffering from preexisting respiratory illnesses.

Like most of the globe, China is dealing with increasing temperatures and longer and more frequent heat waves. But, because of its rapid, energy-intensive development, it's also seeing increased production of the main precursors of ozone, volatile organic compounds (VOCs) and oxides of nitrogen (NOx). In a country as populous as China, this combination poses a serious threat to human health, especially in large urban areas such as Beijing.

Now, a team of collaborating researchers from the Harvard-China Project at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Hong Kong Baptist University has identified large-scale climate patterns that could be used to predict the co-occurrence of extreme heat and ozone days in China months before they occur. Like predictions for hurricane and wildfire seasons, the forecasts could help the government prepare resources and implement policies to mitigate the severity of the season.

The research was published recently in the Proceedings of the National Academy of Sciences.

"We've already seen record-breaking heat waves around the globe this summer, including in China, where local emissions have led to substantial ozone pollution," said Fan Wang, a visiting fellow at SEAS and the Harvard-China Project, Ph.D. candidate at Hong Kong Baptist University, and co-lead author of the study. "Our research could have important implications in the future that would allow agencies such as the Ministry of Ecology and Environment in China to prepare for high summer heat and ozone in springtime."

The research team, led by Michael McElroy, the Gilbert Butler Professor of Environmental Studies at SEAS and the faculty chair of the Harvard-China Project, and Meng Gao, professor at Hong Kong Baptist University and former postdoctoral researcher at SEAS, looked to past meteorological data and daily ozone levels to spot patterns that could be used to predict the season.

Because of the lack of long-term daily observations of ground-level ozone concentrations, the researchers used a sophisticated machine learning model to reconstruct levels back to 2005. Using this dataset, the team identified patterns in sea surface warming in the western Pacific Ocean, the western Indian Ocean and the Ross Sea, off the coast of Antarctica, that preceded summers with high heat and ozone in northeast China, including Beijing.

Warm sea surface temperatures in these regions lead to a decrease in precipitation, cloud cover and circulation across this region of China, known as the North China Plain, which is home to roughly 300 million people.

"These sea surface temperature anomalies influence precipitation, radiation and more, which modulate the co-occurrence of heat waves and ozone pollution," said Gao, co-first author of the paper and Associate of the Harvard-China Project.

The team's model correlated these anomalies with increases in heat waves and ozone about 80 percent of the time.

Governmental agencies could use these predictions to not only issue warnings for human health and agriculture but to reduce the components of ozone and its precursors in the atmosphere before the extreme heat waves hit.

"The ability to forecast prospects for unusually hot summers and unusually high levels of summertime ozone in China simply on the basis of patterns of temperature observed months earlier in remote regions of the ocean is truly exciting," said McElroy.

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Evidence of Ice Age human migrations from China to the Americas and Japan

Scientists have used mitochondrial DNA to trace a female lineage from northern coastal China to the Americas. By integrating contemporary and ancient mitochondrial DNA, the team found evidence of at least two migrations: one during the last ice age, and one during the subsequent melting period. Around the same time as the second migration, another branch of the same lineage migrated to Japan, which could explain Paleolithic archeological similarities between the Americas, China, and Japan. The study appears May 9 in the journal Cell Reports.

"The Asian ancestry of Native Americans is more complicated than previously indicated," says first author Yu-Chun Li, a molecular anthropologist at the Chinese Academy of Sciences. "In addition to previously described ancestral sources in Siberia, Australo-Melanesia, and Southeast Asia, we show that northern coastal China also contributed to the gene pool of Native Americans."

Though it was long assumed that Native Americans descended from Siberians who crossed over the Bering Strait's ephemeral land bridge, more recent genetic, geological, and archeological evidence suggests that multiple waves of humans journeyed to the Americas from various parts of Eurasia.

To shed light on the history of Native Americans in Asia, a team of researchers from the Chinese Academy of Sciences followed the trail of an ancestral lineage that might link East Asian Paleolithic-age populations to founding populations in Chile, Peru, Bolivia, Brazil, Ecuador, Mexico, and California. The lineage in question is present in mitochondrial DNA, which can be used to trace kinship through the female line.

The researchers scoured over 100,000 contemporary and 15,000 ancient DNA samples from across Eurasia to eventually identify 216 contemporary and 39 ancient individuals belonging to the rare lineage. By comparing the accumulated mutations, geographic locations, and carbon-dated age of each of these individuals, the researchers were able to trace the lineage's branching path. They identified two migration events from northern coastal China to the Americas, and in both cases, they think that the travelers probably set dock in America via the Pacific coast rather than by crossing the inland ice-free corridor (which would not have opened at the time).

The first radiation event occurred between 19,500 and 26,000 years ago during the Last Glacial Maximum, when ice sheet coverage was at its greatest and conditions in northern China were likely inhospitable for humans. The second radiation occurred during the subsequent deglaciation or melting period, between 19,000 and 11,500 years ago. There was a rapid increase in human populations at this time, probably due to the improved climate, which may have fueled expansion into other geographical regions.

The researchers also uncovered an unexpected genetic link between Native Americans and Japanese people. During the deglaciation period, another group branched out from northern coastal China and traveled to Japan. "We were surprised to find that this ancestral source also contributed to the Japanese gene pool, especially the indigenous Ainus," says Li.

This discovery helps to explain archeological similarities between the Paleolithic peoples of China, Japan, and the Americas. Specifically, the three regions share similarities in how they crafted stemmed projectile points for arrowheads and spears. "This suggests that the Pleistocene connection among the Americas, China, and Japan was not confined to culture but also to genetics," says senior author Qing-Peng Kong, an evolutionary geneticist at the Chinese Academy of Sciences.

Though the study focused on mitochondrial DNA, complementary evidence from Y chromosomal DNA suggests that male ancestors of Native Americans also lived in northern China at around the same time as these female ancestors.

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Ancient stone tools from China provide earliest evidence of rice harvesting

A new Dartmouth-led study analyzing stone tools from southern China provides the earliest evidence of rice harvesting, dating to as early as 10,000 years ago. The researchers identified two methods of harvesting rice, which helped initiate rice domestication. The results are published in PLOS ONE.

Wild rice is different from domesticated rice in that wild rice naturally sheds ripe seeds, shattering them to the ground when they mature, while cultivated rice seeds stay on the plants when they mature.

To harvest rice, some sort of tools would have been needed. In harvesting rice with tools, early rice cultivators were selecting the seeds that stay on the plants, so gradually the proportion of seeds that remain increased, resulting in domestication.

"For quite a long time, one of the puzzles has been that harvesting tools have not been found in southern China from the early Neolithic period or New Stone Age (10,000 -- 7,000 Before Present) -- the time period when we know rice began to be domesticated," says lead author Jiajing Wang, an assistant professor of anthropology at Dartmouth. "However, when archaeologists were working at several early Neolithic sites in the Lower Yangtze River Valley, they found a lot of small pieces of stone, which had sharp edges that could have been used for harvesting plants."

"Our hypothesis was that maybe some of those small stone pieces were rice harvesting tools, which is what our results show."

In the Lower Yangtze River Valley, the two earliest Neolithic culture groups were the Shangshan and Kuahuqiao.

The researchers examined 52 flaked stone tools from the Shangshan and Hehuashan sites, the latter of which was occupied by Shangshan and Kuahuqiao cultures.

The stone flakes are rough in appearance and are not finely made but have sharp edges. On average, the flaked tools are small enough to be held by one hand and measured approximately 1.7 inches in width and length.

To determine if the stone flakes were used for harvesting rice, the team conducted use-wear and phytolith residue analyses.

For the use-wear analysis, micro-scratches on the tools' surfaces were examined under a microscope to determine how the stones were used. The results showed that 30 flakes have use-wear patterns similar to those produced by harvesting siliceous (silica-rich) plants, likely including rice.

Fine striations, high polish, and rounded edges distinguished the tools that were used for cutting plants from those that were used for processing hard materials, cutting animal tissues, and scraping wood.

Through the phytolith residue analysis, the researchers analyzed the microscopic residue left on the stone flakes known as "phytoliths" or silica skeleton of plants. They found that 28 of the tools contained rice phytoliths.

"What's interesting about rice phytoliths is that rice husk and leaves produce different kinds of phytolith, which enabled us to determine how the rice was harvested," says Wang.

The findings from the use-wear and phytolith analyses illustrated that two types of rice harvesting methods were used -- "finger-knife" and "sickle" techniques. Both methods are still used in Asia today.

The stone flakes from the early phase (10,000 -- 8,200 BP) showed that rice was largely harvested using the finger-knife method in which the panicles at the top of the rice plant are reaped. The results showed that the tools used for finger-knife harvesting had striations that were mainly perpendicular or diagonal to the edge of the stone flake, which suggests a cutting or scraping motion, and contained phytoliths from seeds or rice husk phytoliths, indicating that the rice was harvested from the top of the plant.

"A rice plant contains numerous panicles that mature at different times, so the finger-knife harvesting technique is especially useful when rice domestication was in the early stage," says Wang.

The stone flakes however, from the later phase (8,000 -- 7,000 BP) had more evidence of sickle harvesting in which the lower part of the plant was harvested. These tools had striations that were predominantly parallel to the tool's edge, reflecting that a slicing motion had likely been used.

"Sickle harvesting was more widely used when rice became more domesticated, and more ripe seeds stayed on the plant," says Wang. "Since you are harvesting the entire plant at the same time, the rice leaves and stems could also be used for fuel, building materials, and other purposes, making this a much more effective harvesting method."

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Collapse of ancient Liangzhu culture caused by climate change

Referred to as "China's Venice of the Stone Age", the Liangzhu excavation site in eastern China is considered one of the most significant testimonies of early Chinese advanced civilisation. More than 5000 years ago, the city already had an elaborate water management system. Until now, it has been controversial what led to the sudden collapse. Massive flooding triggered by anomalously intense monsoon rains caused the collapse, as an international team with Innsbruck geologist and climate researcher Christoph Spötl has now shown in the journal Science Advances.

In the Yangtze Delta, about 160 kilometres southwest of Shanghai, the archeological ruins of Liangzhu City are located. There, a highly advanced culture blossomed about 5300 years ago, which is considered to be one of the earliest proofs of monumental water culture. The oldest evidence of large hydraulic engineering structures in China originates from this late Neolithic cultural site. The walled city had a complex system of navigable canals, dams and water reservoirs. This system made it possible to cultivate very large agricultural areas throughout the year. In the history of human civilisation, this is one of the first examples of highly developed communities based on a water infrastructure. Metals, however, were still unknown in this culture. Thousands of elaborately crafted jade burial objects were found during excavations. Long undiscovered and underestimated in its historical significance, the archaeological site is now considered a well-preserved record of Chinese civilisation dating back more than 5000 years. Liangzhu was declared a UNESCO World Heritage Site in 2019. However, the advanced civilisation of this city, which was inhabited for almost 1000 years, came to an abrupt end. Until today, it remains controversial what caused it. "A thin layer of clay was found on the preserved ruins, which points to a possible connection between the demise of the advanced civilisation and floods of the Yangtze River or floods from the East China Sea. No evidence could be found for human causes such as warlike conflicts," explains Christoph Spötl, head of the Quaternary Research Group at the Department of Geology. "However, no clear conclusions on the cause were possible from the mud layer itself."

Dripstones store the answer

Caves and their deposits, such as dripstones, are among the most important climate archives that exist. They allow the reconstruction of climatic conditions above the caves up to several 100,000 years into the past. Since it is still not clear what caused the sudden collapse of the Liangzhu culture, the research team searched for suitable archives in order to investigate a possible climatic cause of this collapse. Geologist Haiwei Zhang from Xi'an Jiaotong University in Xi'an, who spent a year at the University of Innsbruck as a visiting researcher in 2017, took samples of stalagmites from the two caves Shennong and Jiulong, which are located southwest of the excavation site. "These caves have been well explored for years. They are located in the same area affected by the Southeast Asian monsoon as the Yangtze delta and their stalagmites provide a precise insight into the time of the collapse of the Liangzhu culture, which, according to archaeological findings, happened about 4300 years ago," Spötl explains. Data from the stalagmites show that between 4345 and 4324 years ago there was a period of extremely high precipitation. Evidence for this was provided by the isotope records of carbon, which were measured at the University of Innsbruck. The precise dating was done by uranium-thorium analyses at Xi'an Jiaotong University, whose measurement accuracy is ± 30 years. "This is amazingly precise in light of the temporal dimension," says the geologist. "The massive monsoon rains probably led to such severe flooding of the Yangtze and its branches that even the sophisticated dams and canals could no longer withstand these masses of water, destroying Liangzhu City and forcing people to flee." The very humid climatic conditions continued intermittently for another 300 years, as the geologists show from the cave data.

From Science Daily

Blowing up medieval gunpowder recipes

First used for battle in China in about 900 A.D., gunpowder spread throughout Eurasia by the end of the 13th century, eventually revolutionizing warfare as a propellant in firearms and artillery. Meanwhile, master gunners tinkered with gunpowder formulas, trying to find the ideal concoction. Now, researchers reporting in ACS Omega have recreated medieval gunpowder recipes and analyzed the energies released during combustion, revealing that the evolution of the perfect powder was a slow, trial-and-error process.

Although largely obsolete in modern weaponry, gunpowder, also known as black powder, is still used in historical weapons, fireworks and pyrotechnics. The explosive is a combination of varying ratios of potassium nitrate (or "saltpeter"), sulfur and charcoal. Medieval recipes sometimes included interesting additives, such as camphor, varnish or brandy, with obscure purposes. Dawn Riegner, Cliff Rogers and their team of chemists and historians wanted to analyze the energetics of medieval gunpowder recipes to help understand the intent of master gunners in creating these formulas, as well as to provide important technical information about early gunpowder manufacturing.

To do this, the researchers identified over 20 gunpowder recipes from medieval texts dated 1336 to 1449 A.D. They prepared the powders and measured the energies released just before and during combustion using differential scanning calorimetry and bomb calorimetry. They also tested a few of the recipes at a West Point firing range using a replica of an early 15th-century stone-throwing cannon.

In general, in the period 1338-1400 A.D., the percentage of saltpeter increased and charcoal decreased, causing lower heats of combustion, which could have produced safer recipes for medieval gunners. After 1400 A.D., the percentage of saltpeter (the most expensive ingredient) decreased slightly, while sulfur and charcoal increased, raising the heat of combustion, although not as high as for the earliest recipes. Certain additives, such as the combination of camphor and ammonium chloride, appeared to make gunpowder stronger, whereas others, such as water or brandy, did not show energetic advantages, but might have served other purposes. For example, they might have made the material more stable during transport or storage. Although the researchers have characterized the gunpowders in the lab and in limited experiments on the firing range, more field work must be done to evaluate which formulation would perform the best in historical contexts, they say.

From Science Daily