Friday, March 29, 2024

 

Study reveals evidence of violence at a time of crisis in ancient Peru


Analysis of skeletons exhumed at a burial ground dating from the period 500-400 BCE, shortly after the collapse of the Chavín culture, revealed lethal injuries inflicted on men, women and children, as well as signs of material poverty



FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO

Study reveals evidence of violence at a time of crisis in ancient Peru 

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VARIOUS TRAUMATIC INJURIES IN ONE OF THE INDIVIDUALS STUDIED: A) PERIMORTEM PENETRATING FRACTURE IN RIGHT PARIETAL PRODUCED BY BLUNT FORCE TRAUMA; B) CUT MARK IN RIGHT SUPERCILIARY ARCH RELATING TO SHARP FORCE TRAUMA, AND PERIMORTEM INJURY RELATING TO STONE FLAKE, WHICH REMAINS EMBEDDED IN RIGHT WALL OF NASAL PYRIFORM APERTURE; C) HEALED LINEAR PENETRATING FRACTURE AND CUT MARKS IN LEFT ZYGOMATIC BONE RELATING TO SHARP-BLUNT FORCE TRAUMA, AND HEALED NASAL FRACTURE 

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CREDIT: LUIS PEZO-LANFRANCO




The transition from the fifth to the fourth century BCE (Before the Common Era) seems to have been a critical period for the Central Andes, a region now part of Peru. Researchers have found evidence of turbulence during the passage from the Middle Formative period (1200-400 BCE) to the Late Formative period (400-1 BCE). Political disintegration and intergroup violence were apparently part of the context, possibly associated with a shift from theocracy to secular government. A new study, published in the journal Latin American Antiquity, consistently reinforces these suppositions. 

The study was conducted by a team of Peruvian, Colombian and Brazilian researchers led by Peruvian bioarcheologist Luis Pezo-Lanfranco, then affiliated with the Biological Anthropology Laboratory at the University of São Paulo’s Institute of Biosciences (IB-USP) in Brazil. The project was supported by FAPESP via the Grant Program for Young Investigators in Emerging Research Centers. 

“We made a detailed analysis of the skeletal remains of 67 individuals excavated at a burial ground dating from the period 500-400 BCE and located in the Supe Valley region, a few kilometers from Caral, a famous ceremonial center that functioned between 2900 and 1800 BCE. There we detected injury patterns characteristic of repeated events of interpersonal violence. Among the individuals examined, 80% of the adults and adolescents died from inflicted traumatic injuries,” Pezo-Lanfranco told Agência FAPESP. He currently works in the Department of Prehistory at the Autonomous University of Barcelona (UAB) in Spain. 

Perimortem injuries to the skull, face and chest observed in several individuals are compatible with lethal, probably intercommunity, violence, whose victims included children. “Our hypothesis is that a group of strangers came to the community and committed the murders. After the aggressors left, the murder victims were buried by their own people with the usual funeral rites, as suggested by the burial patterns,” he said.

Perimortem means at or near the time of death. Bone damage in perimortem injuries shows no evidence of healing. Bone damage in antemortem injuries shows evidence of healing.

Although perimortem trauma was the most frequent type of injury among the adult skeletons studied, as well as some of the child remains, many examples of antemortem trauma were also found, and several individuals displayed both, suggesting the occurrence of at least two violent events during their lives. The first led to injuries that healed, while the second killed them.

“The markers point to exposure to repetitive and lethal violence during the course of their lives,” Pezo-Lanfranco said. The most frequent injuries were depressed fractures of the cranial vault, other maxillofacial fractures, thoracic fractures (mainly in ribs and scapulae), and “defensive” fractures of the ulna (forearm, indicating an attempt to parry a blow).

Sixty-four of the 67 individuals studied were buried in a fetal position: 12 in dorsal decubitus (lying on their back), four in ventral decubitus (on their stomach), seven in left lateral decubitus (on their left side), and 41 in right lateral decubitus. The fetal position is a recurring burial pattern in prehistoric and ancient communities worldwide. Given its association with the womb, some experts believe it reflects the expectation of rebirth after death. 

Besides the signs of violence, the analysis of the bones showed a high incidence of non-specific stresses and infectious diseases, possibly associated with adverse living conditions due to a combination of a shortage of resources and population growth. The simplicity of most of the grave goods also points to poverty. Many of the skeletons were buried with plain cotton fabric, woven mats and basketry, gourds containing vegetables, cotton seeds and roots, necklaces, and pottery. “Stable isotope studies showed that staple crops were the basis for their subsistence,” Pezo-Lanfranco said.

Competition for scant resources in the Supe Valley region was probably a major factor in the collapse of the Chavín culture, which spread through Peru’s mountains and coast between 1200 and 500 BCE. Its center was Chavín de Huantar, a monumental ceremonial site in northern Peru in the Marañon River basin. The Marañón rises in the Peruvian Andes at about 5,800 m, first flowing northwest and then turning northeast to meet the Ucayali and become the Upper Amazon and Solimões in Brazil.

“The Chavín system reached exhaustion during the Middle to Late Formative transition, around 500-400 BCE. Several ceremonial centers, including Chavín de Huantar, were desacralized and abandoned. Political formations organized around the religious sphere disintegrated, perhaps characterizing the decline of theocracy and the emergence of secular government,” Pezo-Lanfranco said.

The Chavín people worshipped a “zooanthropomorphic” deity resembling a man-jaguar. Gods that combine animal and human attributes are featured in many ancient cultures around the world, including those of Crete, India and Egypt. In a purely speculative approach, some scholars think they may be later re-elaborations of prehistoric shamanic traditions in which the virtues of tutelary animals are syncretized in the figure of the shaman. This hypothesis cannot be confirmed on the basis of existing knowledge.

The name of the Chavín man-jaguar god is unknown. Unlike ancient civilizations in the Old World, the Andean people who worshiped the deity left no written records that could be deciphered to furnish more detailed information. It is worth stressing that the period in question preceded the formal establishment of the Inca Empire by almost 2,000 years. Founded by Pachacuti in 1438 CE (Common Era), the Inca Empire was the ultimate expression of thousands of years of Andean civilizations, yet it lasted for less than 100 years. The Spanish executed the last reigning Inca Emperor, Atahualpa, in 1533, and in 1572 captured and killed Túpac Amaru in Vilcabamba, where he had been leading the resistance. 

For the researchers who conducted the study, the results are particularly important because of what they reveal about an era of ancient Andean history that has so far been poorly documented. Few burial grounds from the period in the Central Andes have been excavated, and still fewer have been found to contain remains as well-conserved as these. Their conservation is due mainly to the dry climate in the region, permitting detailed observation of injuries in almost intact bones. 

“The study belongs to a field we call the ‘bioarcheology of violence”, which helps understand the nature of interpersonal conflict around the middle of the first millennium before the common era. On the other hand, data from the same analysis, to be published soon, offers several answers regarding factors in this society that modulated morbidity and mortality, which developed in the hypothetical context of population pressure and political transition associated with the collapse of belief systems in a highly resource-poor environment,” Pezo-Lanfranco said.

About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

 

UK's summer 2022 drought provides warning for future years


Scientists say improved real-time monitoring and forecasting systems would inform early mitigation measures


UK CENTRE FOR ECOLOGY & HYDROLOGY

Pentwyn Reservoir 2022 

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PENTWYN RESERVOIR DURING THE 2022 DROUGHT

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CREDIT: PHOTO: ALAN HUGHES VIA WIKIMEDIA COMMONS




The UK will be increasingly tested by more droughts like 2022, emphasising the importance of being prepared for similar extreme weather in future, say scientists who have analysed that summer’s events.

The newly published study by the UK Centre for Ecology & Hydrology (UKCEH) outlines how the drought evolved and its impacts on water resources, wildlife and people, comparing the situation with previous droughts and looks at whether it is an indication of future events.

Summer 2022 was the joint hottest (with 2018) and fifth driest since the 1890s. The drought affected large parts of the country and was the worst in some areas since 1976. It was part of wider European drought, believed to be the worst on the continent in 500 years.

The prolonged and extensive exceptional heat, dry soils and low river flows had impacts across much of the UK including water restrictions – with six companies introducing hosepipe bans affecting around 20 million people – and restrictions on waterways navigation.

Extensive challenges for agriculture included low crop and milk yields, as well as dying grass in grazing fields that forced farmers to use winter food stores. During the summer, there were nearly 25,000 wildfires; they spread easily across dry fields and also affected urban areas. Environmental impacts included algal blooms and fish kills.

A Level 4 heat health alert was issued for the first time since its introduction in 2004, and an estimated 2,800 excess deaths of over 65s due to heat between June and August.

That summer’s events underline our continuing vulnerability to intense droughts associated with low spring/summer rainfall alongside very high temperatures – especially given it followed shortly another intense summer drought in 2018.

UKCEH hydrologist Jamie Hannaford, one of the authors of the study, said: “The 2022 drought posed significant challenges to water management and communication with the public given the speed of onset of drought conditions and impacts. It has provided water managers with an important stress test, enabling them to assess our resilience to the kind of extreme event that we will see much more of in future.”

Hydrologists classify 2022 as a summer drought, which developed relatively quickly, as opposed to a multi-year drought driven by successive dry winters. While there is significant uncertainty about how multi-year droughts may evolve in future, scientists are highly confident, based on modelling, that we will be increasingly tested by more droughts like 2022. Human-driven climate warming increases the risk of droughts like 2018 and 2022, associated with drier summers and higher temperatures.

The authors of the study, published in the Royal Meteorological Society journal Weather, say the impacts on water supply were relatively modest in terms of duration and areas affected. Like 2018, this was largely due to wetter winters before and after the drought.

They say droughts like 2022 emphasise the need for improved real-time monitoring and forecasting systems. This would give an indication of the likely impacts that may lie ahead, to help apply mitigation measures – such as restrictions on abstractions or efforts to safeguard the environment like fish rescues – at an early stage.

UKCEH oversees COSMOS-UK, a long-term network of soil moisture monitoring sites, producing live data, which was used for the 2022 drought study.

It is also leading the development of a Floods and Droughts Research Infrastructure (FDRI), funded by UK Research and Innovation (UKRI). The new instruments will produce an extensive range of new measurements across several UK catchments. The data will enable researchers to improve computer models to predict when and where droughts and floods will happen, and how severe they will be. 

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Paper information

Barker et al. 2024. An appraisal of the severity of the 2022 drought and its impacts. Weather. DOI: 10.1002/wea.4531. Open access.

The study was carried out as part of UKCEH work funded by the Natural Environment Research Council, including the National Hydrological Monitoring Programme and CANARI.

Media enquiries

For interviews and more information, please contact Simon Williams, Media Relations Officer at UKCEH, via simwil@ceh.ac.uk or +44 (0)7920 295384.

About the UK Centre for Ecology & Hydrology (UKCEH)

The UK Centre for Ecology & Hydrology is a centre for excellence in environmental science across water, land and air. We have a long history of investigating, monitoring and modelling environmental change, and our science makes a positive difference in the world.

Combining expertise in hydro-meteorology with data derived from national monitoring networks, we measure and model water to accurately predict, mitigate and manage the impacts of floods and droughts. 

The UK Centre for Ecology & Hydrology is a strategic delivery partner for the Natural Environment Research Council, part of UK Research and Innovation.

www.ceh.ac.uk / @UK_CEH / LinkedIn: UK Centre for Ecology & Hydrology

 

 

Movement of crops, animals played a key role in domestication



WASHINGTON UNIVERSITY IN ST. LOUIS
Xinyi Liu 

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XINYI LIU IS AN ARCHAEOLOGIST OF FOOD AND ENVIRONMENT WHO STUDIES PLANT DOMESTICATION, AGRICULTURAL ORIGINS AND PREHISTORIC FOOD GLOBALIZATION.

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CREDIT: WASHINGTON UNIVERSITY IN ST. LOUIS




Archaeologist Xinyi Liu at Washington University in St. Louis teamed up with Martin Jones of the University of Cambridge to write a new paper for the Proceedings of the National Academy of Sciences that explains how recent research is connecting the science of biological domestication to early food globalization.

Liu, an associate professor of archaeology and associate chair of the Department of Anthropology in Arts & Sciences, proposes a new conceptual framework to understand domestication, which is relevant not only to anthropology but other fields such as biology and ecology.

In this Q&A, he also offers his perspective on how understanding the past conditions can help us to forge a vision for the future.

***

The domestication of plants and animals is among the most significant transitions in human history. How has our understanding of domestication changed recently?

Our new article focuses on how we conceptualize domestication. A considerable intellectual legacy has depicted domestication as a series of short-lived, localized and episodic events. Some of the literature, particularly those pieces dating back to the early 20th century, envisioned the process as a transition from humans within nature to humans controlling nature in a revolutionary fashion.

The metaphor there is “revolution.” So, as people described it, there was a “Neolithic Revolution” that functioned in a similar way as the “Industrial Revolution” or the “scientific revolution” — a rapid technological shift followed by changes in societies, according to some narratives.

It is time to reconsider all this. Newly emergent evidence from the last 15 years challenges the idea of rapid domestication. This evidence shows unambiguously that plant and animal domestication in a range of species entailed a more gradual transition spanning a few thousand years across extensive geographies.

How has archaeology contributed to this line of inquiry?

Much of this evidence was brought to light by archaeological and scientific investigations. For example, it took about 5,000 years for the domestication traits of wheat to be fully developed from its wild morphology, according to archaeobotanical work in the Near East. In the lower Yangtze Valley in China, research informed a similar process that ancient communities had cultivated rice for a few millennia before the plant reached domesticated states, in the biological sense.

So domestication has extended in time. But you also argue that it has extended in space. What does that mean?

Over the last 15 years we’ve also seen an improvement in the understanding of how people have moved domesticated plants and animals over continents. In some cases, people moved crops and stocks before the genetic changes associated with domestication were fully fixed within the species. This raises questions about the role translocations played in the domestication process.

Central to our inquiry is the relationship between domesticated crops and stocks and their free-living ancestors, or progenitors. Newer genetic evidence suggests that long-term gene flow between wild and domestic species was much more common than previously appreciated.

It makes sense: At the so-called domestication center, where ancestral varieties were dominant, such gene flow would have been very strong. No meaningful mechanism could have stopped the introgression.

But if farmers took their crops, or herders their stocks, and moved to a new environment beyond the natural distribution of the ancestors, then selection pressures would have changed dramatically. Eventually you are domesticating in a single pathway, with no return. Such a process has been documented genetically and archaeologically in a number of domesticated species, such as maize and wheat.

How do human preferences or traditions factor in?

If crop or stock movements were entangled with the domestication process, the newly introduced species would have to adapt to the new physical environment encountered. But they would have also been adapted to align with new cultural habits. We envision both the physical and cultural adaptation played roles in the fixation of some domestication traits.

Does this research have any implications for modern agriculture?

Understanding the past conditions can help us to forge visions about the future. In that sense, archaeology plays a key role in establishing the historical and community roots of a range of contemporary challenges, such as food security, planetary health and sustainability, providing solutions drawing from humanity at the deepest level.

One such example is the positive impact that archaeogenetic research about millet made on the livelihoods of farmers across the globe. At its 75th session, the United Nations General Assembly declared 2023 the International Year of Millets to raise awareness of the crop’s deep community roots and future potential. There has been considerable recent momentum in understanding the biodiversity and historical geography of millets, which are a diverse group of cereals originating from several continents, including pearl, proso (or broomcorn), foxtail, barnyard, little, kodo, browntop, finger and fonio millets.

Millets can grow on arid lands with minimal inputs and are resilient to changes in climate. They are, therefore, an ideal solution for communities to increase self-sufficiency and reduce reliance on imported cereal grains.

These grains once sustained ancient populations by large. Archaeology played a key role in establishing the original biogeography, domestication and early dispersals of millets. The knowledge we have gained consequently has profoundly impacted food security and conservation in areas where millets are culturally relevant.

 

Carbon credits would enable restoration of UK saltmarshes say experts


Feasibility study backs introduction of UK Saltmarsh Code and carbon trading scheme


UK CENTRE FOR ECOLOGY & HYDROLOGY

Ribble Estuary 

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SALTMARSH IN THE RIBBLE ESTUARY

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CREDIT: STEFANIE CARTER




While the marshes may have meant danger for Pip in Great Expectations, these wetland habitats are important wildlife havens and mitigate climate change.

However, since Dickens’s celebrated novel was published in 1860, 85% of England’s saltmarsh has been lost as land has been claimed from the sea for agriculture, development or coastal flood defences. This has resulted in the release of greenhouse gases as well as the loss of biodiversity and natural buffer zones protecting properties and infrastructure from flooding.

The introduction of a carbon credit scheme, enabling companies to invest in the restoration of the UK’s degraded saltmarshes and voluntarily offset their greenhouse gas emissions, would be viable, a study led by the UK Centre for Ecology & Hydrology (UKCEH) has found.

A partnership of scientists, charities and financial experts investigated the feasibility of a Saltmarsh Carbon Code, similar to the existing Peatland and Woodland codes, which would create a rigorous and scientifically-based voluntary certification standard for saltmarsh carbon to be marketed and traded by UK companies. This would assure buyers of carbon credits that the climate benefits being sold are real, quantifiable, additional and permanent.

The independent study, funded by a UK Government grant, found the introduction of a UK-wide code and carbon credit scheme would be feasible, and provide a pipeline for private investment to contribute to restoration projects, providing there was also some level of public financing in restoration projects.

So far, there has been relatively limited saltmarsh restoration in the UK, with the majority of schemes to date providing compensatory habitat for damage to designated sites due to development. However, there is an increasing interest by companies in carbon credits, which could accelerate saltmarsh restoration.

At present, the UK only has about 45,000 hectares of natural saltmarsh remaining. It is estimated that these accumulate up to around 700,000 tonnes of CO2 a year and the top 10cm of UK saltmarsh soil hold a total of around 2.3 million tonnes of carbon.

The total amount of carbon sequestration could increase with effective restoration, which usually involves managed realignment of coastline by deliberating reflooding land to restore a coastal wetland habitat. Saltmarshes trap and bury atmospheric carbon in the sediment beneath them and the vegetation that grows on them.

UKCEH wetland scientist Annette Burden led the study, which also involved WWT, RSPB, the University of St Andrews, Bangor University, SRUC, IUCN National Committee UK, Finance Earth and Jacobs.

She says: “Saltmarshes can play an important role in addressing the climate and biodiversity crises. Restoring sites across the country would support progress towards our net zero targets and provide vital habitat for wildlife, including overwintering migratory birds and commercially important fish species such as Seabass.

“The introduction of a Saltmarsh Code would pave the way for private investment to support projects that have some public financing but would not otherwise happen.”

Varying factors such as ground conditions, design complexity and compensation to landowners mean the cost of restoration can be unpredictable, even after restoration work has begun, which is why public financing is considered essential to cover some of the costs.

The research team looked at how much of the cost of the planned restoration of RSPB Old Hall Marshes in Essex could be covered by private investment and reviewed whether carbon finance could have raised enough funds for the managed realignment of WWT Steart Marshes in Somerset which was carried out in 2014.

The analysis found that with grants, the WWT Steart Marshes scheme would have been able to generate market rate returns for equity investors, and therefore attract sufficient investment to be financially viable. The project team, backed by further Environment Agency/Defra funding, is now developing a pilot Saltmarsh Code for further testing, with the hope that a saltmarsh carbon credits system could be introduced in 2025.

The feasibility study and more information about the ongoing work on the Saltmarsh Code are available on the UKCEH website. 

UKCEH has produced a podcast on the role and importance saltmarshes as part of its Counting the Earth series, as well as a saltmarsh factsheet.

Our scientists are establishing the first network of greenhouse gas monitoring stations on saltmarshes around the UK coast. These flux towers will measure how much carbon dioxide gas is captured from the atmosphere and stored as carbon within the saltmarsh ecosystem.

– Ends –

Media enquiries

For interviews and more information, please contact Simon Williams, Media Relations Officer at UKCEH, via simwil@ceh.ac.uk or +44 (0)7920 295384.

 

Notes to Editors

The Saltmarsh Code project was funded by a £100,000 grant from the Natural Environment Investment Readiness Fund (NEIRF), an initiative by the Department for Environment, Food and Rural Affairs (Defra), the Environment Agency and Natural England which aims to stimulate private investment to improve and safeguard our natural environment. Ongoing work until March 2025 is funded by a £200,000 grant from the Environment Agency and Defra.

The UKCEH-led saltmarsh feasibility report suggested a price cap of £150 per saltmarsh carbon credit, which is considered by Finance Earth to be a conservative assumption, given the recent significant increases in voluntary carbon prices in the UK and globally.

The project team suggested the introduction of a UK-wide saltmarsh code, concluding the cost of adopting the VM0033 international verification scheme was likely to make most projects not financially viable.

Given the uncertainty over potential carbon accumulation rates for different saltmarsh sites, the researchers calculated a range of estimates for their two case studies.

About the UK Centre for Ecology & Hydrology (UKCEH)

The UK Centre for Ecology & Hydrology is a world-leading centre for excellence in environmental sciences across water, land and air. We have a long history of monitoring and modelling environmental change.

UKCEH undertakes long-term national surveys of both natural and managed environments, focusing on carbon dioxide, methane and nitrous oxide. We make a major contribution to the UK national and international greenhouse gas emissions inventories, and we improve understanding of the role that land use has on emissions. We are contributing to the development of peatland and saltmarsh carbon codes – voluntary certification standards, enabling peatland and saltmarsh carbon to be marketed and purchased by private investors – thereby providing an income stream for the achievement of national net zero goals.

The UK Centre for Ecology & Hydrology is a strategic delivery partner for the Natural Environment Research Council, part of UK Research and Innovation.

www.ceh.ac.uk / @UK_CEH /  LinkedIn: UK Centre for Ecology & Hydrology

 

US Doctors received approximately $12.1 billion from drug and device makers between 2013-2022


Peer-Reviewed Publication

PENN STATE





HERSHEY, Pa. — Despite evidence that financial conflicts of interest may influence medical practice and research and may erode patient trust in medical professionals, these relationships remain pervasive. According to a new analysis of the Open Payments platform, a database that tracks payments between physicians and industry, a team led by a Penn State researcher found that doctors received approximately $12.1 billion from drug and device makers between 2013 and 2022. 

Their findings published today (March 28) in JAMA. It’s one of the first studies to look at industry payments longitudinally and by specialty. 

“Overall, it shows that the Open Payments is not much more than a ledger sheet. Whether there is a need for deterrence or changed behaviors requires a broader conversation with public involvement,” said Andrew Foy, associate professor, Penn State College of Medicine and corresponding author on the paper.

In 2013, the Physician Payments Sunshine Act was passed in response to calls for greater transparency on financial relationships between physicians and teaching hospitals and the makers of drugs and medical devices. It led to the creation of the Open Payments database. Manufacturers are required to submit information on all payments and transfers of value.

For this paper, the team used data from Open Payments from 2013 to 2022. They included payments (both cash and non-cash equivalents) to physicians for consulting services, non-consulting services, food and beverages, travel and lodging, entertainment, education, gifts, grants, charitable contributions and honoraria. They analyzed data across 39 specialties. They also looked at within-specialty variation — the difference between the median amount paid to physicians in a specialty and the mean amount paid to the top 0.1% of physicians in that specialty. Lastly, they determined the 25 drugs and medical devices associated with the largest total payments.

The analysis showed that more than half of physicians received at least one payment and roughly 94% of payments were associated with one or more marketed medical product. A small percentage of physicians received the largest amounts, often exceeding $1 million. Orthopedic surgeons received the greatest sum of payments while pediatric surgeons received the least amount. 

Other authors on the paper are Ahmed Sayed from Ain Shams University, Joseph Ross from Yale School of Medicine, John Mandrola from Baptist Health, Lisa Soleymani Lehmann from Harvard Medical School.

This project was not supported by external grants or funds.

 

Manganese plays a surprising role in soil carbon sequestration


Exchangeable manganese, like that emitted by industry, cuts carbon storage in boreal forests


DUKE UNIVERSITY

Boreal Forest in Daxing'an Mountains, China 

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A SCENE FROM THE BOREAL FOREST OF THE DAXING'AN MOUNTAINS IN CHINA.

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CREDIT: JINGHUA YU




DURHAM, N.C. – Manganese in the soil of boreal forests has been found to work against the carbon storage capacity of these crucial northern habitats.

Located predominantly in cold regions at high latitude, boreal forests are estimated to store nearly 30 percent of the world’s soil carbon, making them the world’s largest reservoir of land-based carbon. This stored carbon is found mostly in the forests’ humus layer, which contains decomposed leaves and other organic matter.

A global, long-term study led by Duke University researchers has found that higher levels of manganese in this layer stimulated decomposition of soil organic matter, and released more carbon dioxide than did those forest plots with less or no manganese. The work appeared March 19  in the Proceedings of the National Academy of Sciences (PNAS).

“Conventional wisdom is these forests are like a global vault of carbon, where carbon is put into the vault versus taken out,” said William H. Schlesinger, professor emeritus at Duke University’s Nicholas School of the Environment and study co-author. “These findings reveal a crack in the vault, where enough manganese over time stimulates the release of carbon dioxide into the atmosphere, which has implications for climate mitigation efforts and the global carbon cycle,” said Schlesinger. 

Certain industrial processes, such as metal smelting or combustion of manganese-containing fuels, can release airborne manganese which is later deposited in soils downwind. 

This is one of many human activities, such as the burning of fossil fuels, deforestation, and land-use changes, that have disturbed the natural carbon cycle, leading to an increase in atmospheric carbon dioxide concentrations that contribute to global warming and climate change. 

“Carbon inventorying is still an evolving science,” said Yunyu Zhang, lead author and graduate student from the Chinese Academy of Sciences. “It is essential to figure out which factors regulate this huge carbon pool [in boreal forests’ soil], especially given continuous… industrialization.”  

Researchers analyzed data from boreal forests worldwide, and fertilized soil with manganese over 14 years (2009-2023) in China’s Daxing’an Mountains. Results showed the level of exchangeable manganese -- the part of manganese that plants can use as nutrients -- determined how much carbon was stored in boreal forest soil. After four years, carbon storage on plots fertilized with manganese fell by nearly 13 percent, meaning more carbon was released into the atmosphere.  

“To develop effective and sustainable strategies, it is critical to understand complex interactions between trace nutrients and carbon storage,” Zhang said. “It is even more important to predict how those interactions work in the long term, considering the impact of human activities.”    

Schlesinger emphasized the need for further research and action, noting how the study’s findings highlight the importance of soil nutrient dynamics, such as the level of exchangeable manganese, in climate change mitigation efforts.  

He urged further study of the role of manganese not only in soil, but also in the air, on land-based carbon emissions, the boreal forest ecosystem, and climate mitigation.

“There’s no proverbial foolproof vault or absolute forest sink,” Schlesinger said. “We need integrated approaches to land management and climate mitigation. Climate has traditionally been considered a major factor in carbon storage, but we now see how manganese is also a key indicator, something that has long been overlooked and underexamined.” 

The National Natural Science Foundation of China and Chinese Academy of Sciences co-funded the study.

CITATION: “Exchangeable Manganese Regulates Carbon Storage in the Humus Layer of Boreal Forests,” Yunyu Zhang, Sarah E. Hobbie, William H. Schlesinger, Bjorn Berg, Tao Sun, Jiaojun Zhu. Proceedings of the National Academy of Science, March 19, 2024. DOI: 10.1073/pnas.2318382121  

Online: https://www.pnas.org/doi/10.1073/pnas.2318382121