Saturday, June 27, 2020

Ancient Maya reservoirs contained toxic pollution

Mercury, algae made water undrinkable in heart of city

UNIVERSITY OF CINCINNATI

IMAGE: THE ANCIENT CITY OF TIKAL RISES ABOVE THE RAINFOREST IN NORTHERN GUATEMALA. view more

CREDIT: DAVID LENTZ/UC

Reservoirs in the heart of an ancient Maya city were so polluted with mercury and algae that the water likely was undrinkable.

Researchers from the University of Cincinnati found toxic levels of pollution in two central reservoirs in Tikal, an ancient Maya city that dates back to the third century B.C. in what is now northern Guatemala.

UC's findings suggest droughts in the ninth century likely contributed to the depopulation and eventual abandonment of the city.

"The conversion of Tikal's central reservoirs from life-sustaining to sickness-inducing places would have both practically and symbolically helped to bring about the abandonment of this magnificent city," the study concluded.

A geochemical analysis found that two reservoirs nearest the city palace and temple contained toxic levels of mercury that UC researchers traced back to a pigment the Maya used to adorn buildings, clayware and other goods. During rainstorms, mercury in the pigment leached into the reservoirs where it settled in layers of sediment over the years.

But the former inhabitants of this city, made famous by its towering stone temples and architecture, had ample potable water from nearby reservoirs that remained uncontaminated, UC researchers found.

The study was published in the Nature journal Scientific Reports.

UC's diverse team was composed of anthropologists, geographers, botanists, biologists and chemists. They examined layers of sediment dating back to the ninth century when Tikal was a flourishing city.

Previously, UC researchers found that the soils around Tikal during the ninth century were extremely fertile and traced the source to frequent volcanic eruptions that enriched the soil of the Yucatan Peninsula.

"Archaeologists and anthropologists have been trying to figure out what happened to the Maya for 100 years," said David Lentz, a UC professor of biological sciences and lead author of the study.

For the latest study, UC researchers sampled sediment at 10 reservoirs within the city and conducted an analysis on ancient DNA found in the stratified clay of four of them.

Sediment from the reservoirs nearest Tikal's central temple and palace showed evidence of toxic algae called cyanobacteria. Consuming this water, particularly during droughts, would have made people sick even if the water were boiled, Lentz said.

"We found two types of blue-green algae that produce toxic chemicals. The bad thing about these is they're resistant to boiling. It made water in these reservoirs toxic to drink," Lentz said.

UC researchers said it is possible but unlikely the Maya used these reservoirs for drinking, cooking or irrigation.

"The water would have looked nasty. It would have tasted nasty," said Kenneth Tankersley, an associate professor of anthropology in UC's College of Arts and Sciences. "There would have been these big algae blooms. Nobody would have wanted to drink that water."

But researchers found no evidence of the same pollutants in sediments from more distant reservoirs called Perdido and Corriental, which likely provided drinking water for city residents during the ninth century.

Today, Tikal is a national park and a UNESCO World Heritage site. Researchers believe a combination of economic, political and social factors prompted people to leave the city and its adjacent farms. But the climate no doubt played a role, too, Lentz said.

"They have a prolonged dry season. For part of the year, it's rainy and wet. The rest of the year, it's really dry with almost no rainfall. So they had a problem finding water," Lentz said.

Co-author Trinity Hamilton, now an assistant professor of biology at the University of Minnesota, worked on the analysis of ancient DNA from algae that sank to the reservoir bottom and was buried by centuries of accumulated sediment.

"Typically, when we see a lot of cyanobacteria in freshwater, we think of harmful algal blooms that impact water quality," Hamilton said.

Finding some reservoirs that were polluted and others that were not suggests the ancient Maya used them for different purposes, she said.

Reservoirs near the temple and palace likely would have been impressive landmarks, much like the reflecting pool at the National Mall is today.

"It would have been a magnificent sight to see these brightly painted buildings reflected off the surface of these reservoirs," said co-author Nicholas Dunning, head of geography in UC's College of Arts and Sciences.

"The Maya rulers conferred to themselves, among other things, the attribute of being able to control water. They had a special relationship to the rain gods," Dunning said. "So the reservoir would have been a pretty potent symbol."

UC's Tankersley said one popular pigment used on plaster walls and in ceremonial burials was derived from cinnabar, a red-colored mineral composed of mercury sulfide that the Maya mined from a nearby volcanic feature known as the Todos Santos Formation.

A close examination of the reservoir sediment using a technique called energy dispersive X-ray fluorescence spectrometry found that mercury did not leach into the water from the underlying bedrock. Likewise, Tankersley said, UC ruled out another potential source of mercury -- volcanic ash that fell across Central America during the frequent eruptions. The absence of mercury in other nearby reservoirs where ash would have fallen ruled out volcanoes as the culprit.

Instead, Tankersley said, people were to blame.

"That means the mercury has to be anthropogenic," Tankersley said.

With its bright red color, cinnabar was commonly used as a paint or pigment across Central America at the time.

"Color was important in the ancient Maya world. They used it in their murals. They painted the plaster red. They used it in burials and combined it with iron oxide to get different shades," Tankersley said.

"We were able to find a mineral fingerprint that showed beyond a reasonable doubt that the mercury in the water originated from cinnabar," he said.

Tankersley said ancient Maya cities such as Tikal continue to captivate researchers because of the ingenuity, cooperation and sophistication required to thrive in this tropical land of extremes.

"When I look at the ancient Maya, I see a very sophisticated people with a very rich culture," Tankersley said.

UC's team is planning to return to the Yucatan Peninsula to pursue more answers about this remarkable period of human civilization.

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Air pollution could help London transport planners fight COVID-19

UNIVERSITY OF BIRMINGHAM

Measuring air quality across London could help fight COVID-19 by providing a rapid means of deciding whether to reduce public transport movement - given strong links between exposure to air pollution and COVID-19 transmission, a new study reveals.

Analysis of air pollution, COVID-19 cases and fatality rates in London demonstrates a connection between increased levels of nitrogen dioxide (NO2) and particulate matter (PM2.5) and higher risk of viral transmission.

Scientists at the Universities of Birmingham and Cambridge say that this shows air pollution could be used as an indicator to rapidly identify vulnerable parts of a city such as London - informing decisions to suspend or reduce operation of buses, trains and Underground.

Researchers have published their findings today in Science of The Total Environment, highlighting that using public transport in the UK during a pandemic outbreak has a six-fold increased risk of contracting an acute respiratory infection.

City boroughs with access to London Underground interchange stations also have higher pandemic case rates as users are exposed to a higher number of individuals compared to through stations.

Report author Dr Ajit Singh, from the University of Birmingham, commented: "Short-term exposure to NO2 and PM2.5is significantly linked to an increased risk of contracting and dying from COVID-19. Exposure to such air pollutants can compromise lung function and increase risk of death from the virus.

"Levels of airborne PM2.5in the London Underground during summer are often several times higher than other transport environments such as cycling, buses or cars. We recommend a strategy that tailors the level of public transport activity in cities like London according to COVID-19 vulnerability based on air pollution levels across the city.

"This could help decision-makers take the right measures to counter COVID-19 in London - for example deploying transport staff and arranging dedicated services for key workers."

Scientists have earlier found the greatest PM2.5concentrations across the London Underground network on the Victoria Line (16 times higher than the roadside environment), followed by the Northern, Bakerloo and Piccadilly lines.

Routine cleaning and maintenance of the London Underground ranges from litter removal to preventing safety incidents rather than reducing PM concentrations.

Co-author Dr Manu Sasidharan, of the University of Cambridge, commented: "Human-mobility reduction measures provide the greatest benefit in the fight against COVID-19. We need to balance the public health benefits of closing public transport during a pandemic against the socio-economic impacts of reducing mobility.

"Determining the vulnerability of city regions to coronavirus might help to achieve such trade-offs - air pollution levels can serve as one of the indicators to assess this vulnerability."

The number of positive COVID-19 cases considered in the study were only those reported at hospitals - it does not include people self-isolating due to COVID-19.

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For more information, please contact Tony Moran, International Communications Manager, University of Birmingham on +44 (0)782 783 2312 or t.moran@bham.ac.uk. For out-of-hours enquiries, please call +44 (0) 7789 921 165.

Notes to Editors

* The University of Birmingham is ranked amongst the world's top 100 institutions, its work brings people from across the world to Birmingham, including researchers and teachers and more than 6,500 international students from over 150 countries.

* 'A vulnerability-based approach to human-mobility reduction for countering COVID-19 transmission in London while considering local air quality' - Manu Sasidharan, Ajit Singh, Mehran Eskandari Torbaghan and Ajith Kumar Parlikad is published in Science of The Total Environment.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy o

Traffic density, wind and air stratification influence concentrations of air pollutant NO2

Leipzig researchers use a calculation method to remove weather influences from air pollution data

LEIBNIZ INSTITUTE FOR TROPOSPHERIC RESEARCH (TROPOS)

IMAGE: TRAFFIC DENSITY, WIND AND AIR STRATIFICATION INFLUENCE THE POLLUTION WITH THE AIR POLLUTANT NITROGEN DIOXIDE, ACCORDING TO THE CONCLUSION OF A TROPOS STUDY COMMISSIONED BY THE LFULG. view more

CREDIT: BURKHARD LEHMANN, LFULG

Leipzig/Dresden. In connection with the effects of the COVID-19 pandemic, satellite measurements made headlines showing how much the air pollutant nitrogen dioxide (NO2) had decreased in China and northern Italy. In Germany, traffic density is the most important factor. However, weather also has an influence on NO2 concentrations, according to a study by the Leibniz Institute for Tropospheric Research (TROPOS), which evaluated the influence of weather conditions on nitrogen dioxide concentrations in Saxony 2015 to 2018 on behalf of the Saxon State Office for Environment, Agriculture and Geology (LfULG). It was shown that wind speed and the height of the lowest air layer are the most important factors that determine how much pollutants can accumulate locally.

In order to determine the influence of various weather factors on air quality, the team used a statistical method that allows meteorological fluctuations to be mathematically removed from long-term measurements. The air quality fluctuates, in some cases very strongly, due to different emissions and the influence of the weather. Until now, however, it has been difficult to estimate, what share legal measures such as low emission zones or diesel driving bans have and what share the weather influences have in the actual air quality? With the method used, this will be easier in the future.

Nitrogen dioxide (NO2) is an irritant gas which attacks the mucous membrane of the respiratory tract, causes inflammatory reactions as an oxidant and increases the effect of other air pollutants. As a precursor substance, it can also contribute to the formation of particulate matter. Limit values have been set in the EU to protect the population: For nitrogen dioxide, an annual average value of 40 micrograms per cubic metre of air applies (μg/m³). To protect the health of the population, measures must be taken if these limit values are not complied with. In 2018/2019, for example, various measures were taken in Germany, ranging from a reduction in the number of lanes (e.g. in Leipzig) to driving bans for older diesel vehicles (e.g. in Stuttgart).

To evaluate the effectiveness of such measures, it would be helpful to determine the exact influence of weather conditions. The Saxon State Office for Environment, Agriculture and Geology (LfULG) therefore commissioned TROPOS to carry out a study on the influence of weather factors on NO2 concentrations and provided its measurement data from the Saxon air quality measurement network and meteorological data for this purpose. The researchers were thus able to evaluate data from 29 stations in Saxony over a period of four years, which represent a cross-section of air pollution - from stations at traffic centres to urban and rural background stations and stations on the ridge of the Erzgebirge mountains. They also calculated the height of the lowest layer in the atmosphere and incorporated data from traffic counting stations in Leipzig and Dresden into the study. A method from the field of machine learning was used for the statistical modelling, the application of which in the field of air quality was first published by British researchers in 2009.

In this way, the study was able to demonstrate that the traffic density at all traffic stations is most significantly responsible for nitrogen oxide concentrations. However, two weather parameters also have a significant influence on nitrogen dioxide concentrations: wind speed and the height of the so-called mixing layer. The latter is a meteorological parameter that indicates the height to which the lowest layer of air, where the emissions mix, extends. "It was also shown that high humidity can also reduce the concentration of nitrogen dioxide, which could be due to the fact that the pollutants deposit more strongly on moist surfaces. However, the exact causes are still unclear," says Dominik van Pinxteren.

The statistical analysis has also enabled the researchers to remove the influence of the weather from the time series of pollutant concentrations: Adjusted for the weather, the concentration of nitrogen oxides (NOx) decreased by a total of 10 micrograms per cubic meter between 2015 and 2018 on average over all traffic stations in Saxony. In urban and rural areas and on the ridge of the Erzgebirge, however, NOx concentrations tend to remain at the same level. Even though there have been some improvements in air quality in recent years, there are good scientific arguments for further reducing air pollution.

In a way, this also applies to premature conclusions from the corona crisis: in order to find out how strong the influence of the initial restrictions on air quality actually was, the influence of the weather would have to be statistically removed in a longer series of measurements. To this end, investigations for the Leipzig area are currently underway at TROPOS, as is a Europe-wide study of the EU research infrastructure for short-lived atmospheric constituents such as aerosol, clouds and trace gases (ACTRIS), the German contribution to which is coordinated by TROPOS. Tilo Arnhold

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Publication:

Dominik van Pinxteren, Sebastian Düsing, Alfred Wiedensohler, Hartmut Herrmann (2020): Meteorological influences on nitrogen dioxide: Influence of weather conditions and weathering on nitrogen dioxide concentrations in outdoor air 2015 to 2018. Series of publications of the LfULG, issue 2/2020 (in German only) https://publikationen.sachsen.de/bdb/artikel/35043

This study was commissioned by the State Office for Environment, Agriculture and Geology (LfULG).

Project:

LfULG-Projekt „Meteorologische Einflüsse auf Stickstoffdioxid": https://www.luft.sachsen.de/Inhalt_FuE_Projekt_Witterung_NOx_Ozon.html

Study finds strong evidence for a causal link between long-term exposure to fine air particles and greater mortality in elderly Americans

Evaluating the impact of long-term exposure to fine particulate matter on mortality among the elderly

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE

A new analysis of 16 years of publicly accessible health data on 68.5 million Medicare enrollees provides broad evidence that long-term exposure to fine particles in the air - even at levels below current EPA standards - leads to increased mortality rates among the elderly. Based on the results of five complementary statistical models, including three causal inference methods, the researchers estimate that if the EPA had lowered the air quality standard for fine particle concentration from 12 μg/m3 down to the WHO guideline of 10 μg/m3, more than 140,000 lives might have been saved within one decade. "Our findings provide the strongest evidence to date that current national air quality standards aren't sufficiently protective of Americans' health," said corresponding author Francesca Dominici. "Now, in the middle of a pandemic that attacks our lungs and makes us unable to breathe, it is irresponsible to roll back environmental policies," she added. The new study is likely to inform national discussions around updating air quality standards, for example, the National Ambient Air Quality Standards by the EPA.

A number of studies have documented a strong correlation between long-term exposure to fine particulate and greater human mortality, but some concern has remained about the causal nature of the evidence, and whether it is sufficient to inform revisions to air quality standards. Some scientists argue that modern causal inference methods can provide such evidence, using the right data. "Causal inference can quantify and visualize how close our data are to approximating a randomized controlled study, the gold standard for assessing causation," said the study's lead author Xiao Wu. Analyzing a massive dataset through five distinct approaches, including two traditional statistical methods and three causal inference methods, Wu and colleagues derived broad evidence consistent with a causal link between long-term particulate exposure and mortality. Modeling a 10 μg/m3 decrease of fine particle concentration between 2000 and 2016 resulted in a 6% to 7% decrease in mortality risk. Based on their model results, the researchers estimated that more than 140,000 lives might have been saved if the current U.S. standard for fine particle concentration had been lowered to 10 μg/m3 between 2007 and 2016. The authors emphasize the urgent need to modify particulate concentration levels to help protect elderly individuals with respiratory diseases living in polluted areas.

https://www.eurekalert.org/pub_releases/2020-06/aaft-sfs062620.php

Children more resilient against coronavirus, study reveals

Texas team reviews 131 studies of children from 26 countries

UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER AT SAN ANTONIO

IMAGE: ALVARO MOREIRA, MD, MSC, OF THE LONG SCHOOL OF MEDICINE AT UT HEALTH SAN ANTONIO, LED A STUDY TEAM THAT FOUND CHILDREN INFECTED WITH THE CORONAVIRUS FARED BETTER THAN ADULTS.... view more

CREDIT: UT HEALTH SAN ANTONIO

SAN ANTONIO - The majority of children with COVID-19 in 26 countries fared well clinically compared to adults during the first four months of the pandemic, a newly released study shows.

Researchers from the Long School of Medicine at The University of Texas Health Science Center at San Antonio prepared the study, which is the largest systematic review to date of children and young adults with COVID-19. EClinicalMedicine, a journal of The Lancet, on June 26 published the results, which cover studies published between Jan. 24 and May 14.

Among the findings:

19% of the pediatric population with COVID-19 had no symptoms.
21% exhibited patchy lesions on lung X-rays.
5.6% suffered from co-infections, such as flu, on top of COVID-19.
3.3% were admitted to intensive care units.
Seven deaths were reported.

"Our data is compiled from 131 studies and encompasses 7,780 patients who span the pediatric age spectrum," said study senior author Alvaro Moreira, MD, MSc, assistant professor of pediatrics at UT Health San Antonio and a fellowship-trained neonatologist.

"In the study we report the most common symptoms, quantify laboratory findings and describe imaging characteristics of children with COVID-19," Dr. Moreira said. "Furthermore, we summarize treatments that were administered and offer an initial glimpse of a handful of patients who met the U.S. Centers for Disease Control and Prevention (CDC) criteria for multisystem inflammatory syndrome in children."

Symptoms

The most frequent symptoms, similar to the adult population, were fever and cough. Those were found in 59% and 56% of the pediatric population.

In 233 individuals, a past medical history was noted, and among this group, 152 were children with compromised immune systems or who had underlying respiratory or cardiac disease.

The number of children with excellent outcomes surprised the research team. "Although we are hearing about severe forms of the disease in children, this is occurring in very rare circumstances," Dr. Moreira said.

The majority of journal articles were from China. The largest study that was included was a case series of 2,572 patients reported by the U.S. CDC COVID-19 team.

Laboratory measures that were consistently abnormal in pediatric COVID-19 patients included inflammatory markers such as creatine kinase, interleukin-6 and procalcitonin.

Few severe cases

Thankfully, only a small number of patients met inclusion for multisystem inflammatory syndrome in children. Their disease paralleled the extreme forms of COVID-19 seen in adults.

"Children with systemic inflammation had a significant decrease in the amount of lymphocytes in their blood," Dr. Moreira said. "COVID-positive children who didn't have the extreme form of the disease had 42% lymphocytes in their blood, versus 11% in children with the multisystem syndrome."

Lymphocytes are one of the main types of immune cells in the body.

Kidney failure was seen in nine pediatric patients, liver failure also in nine and shock in 19. Mechanical ventilation was required by 42 patients.

The study does not take into consideration a new surge of patients in New York, England and Italy where specialists are now starting to see children with multisystem inflammatory syndrome, Dr. Moreira said.

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In addition to Dr. Moreira, the team consists of two study co-first authors who are medical students in the Long School of Medicine; a pediatric intensive care fellow at Texas Children's Hospital in Houston; undergraduate students from Texas A&M, The University of Texas at San Antonio and Cottey College; a student accepted into the McGovern Medical School at UTHealth in Houston; and a San Antonio high school student.

COVID-19 in 7,780 pediatric patients A systematic review

Ansel Hoang, Kevin Chorath, Axel Moreira, Mary Evans, Finn Burmeister-Morton, Fiona Burmeister, Rija Naqvi, Matthew Petershack, Alvaro Moreira, MD, MSc

First published: June 26, 2020, EClinicalMedicine

https://doi.org/10.1016/j.eclinm.2020.100433

The Long School of Medicine at The University of Texas Health Science Center at San Antonio is named for Texas philanthropists Joe R. and Teresa Lozano Long. The school is the largest educator of physicians in South Texas, many of whom remain in San Antonio and the region to practice medicine. The school teaches more than 900 students and trains 800 residents each year. As a beacon of multicultural sensitivity, the school annually exceeds the national medical school average of Hispanic students enrolled. The school's clinical practice is the largest multidisciplinary medical group in South Texas with 850 physicians in more than 100 specialties. The school has a highly productive research enterprise where world leaders in Alzheimer's disease, diabetes, cancer, aging, heart disease, kidney disease and many other fields are translating molecular discoveries into new therapies. The Long School of Medicine is home to a National Cancer Institute-designated cancer center known for prolific clinical trials and drug development programs, as well as a world-renowned center for aging and related diseases.

The University of Texas Health Science Center at San Antonio, also referred to as UT Health San Antonio, is one of the country's leading health sciences universities and is designated as a Hispanic-Serving Institution by the U.S. Department of Education. With missions of teaching, research, patient care and community engagement, its schools of medicine, nursing, dentistry, health professions and graduate biomedical sciences have graduated more than 37,000 alumni who are leading change, advancing their fields, and renewing hope for patients and their families throughout South Texas and the world. To learn about the many ways "We make lives better®," visit http://www.uthscsa.edu.

Stay connected with The University of Texas Health Science Center at San Antonio on Facebook, Twitter, LinkedIn, Instagram and YouTube.

To see how we are battling COVID-19, read inspiring stories on Impact.

Life in the galaxy: maybe this is as good as it gets?

GOLDSCHMIDT CONFERENCE

IMAGE: GALAXY M51 IS A SPIRAL GALAXY, ABOUT 30 MILLION LIGHT YEARS AWAY, THAT IS IN THE PROCESS OF MERGING WITH A SMALLER GALAXY SEEN TO ITS UPPER LEFT. view more

CREDIT: IMAGE CREDIT: X-RAY: NASA/CXC/SAO; OPTICAL: DETLEF HARTMANN; INFRARED: COURTESY NASA/JPL-CALTECH. HI-DEFINITION IMAGE AVAILABLE AT HTTPS://WWW.NASA.GOV/MISSION_PAGES/CHANDRA/MULTIMEDIA/SPIRAL-GALAXY-M51.HTML...

Researchers have found that rocky exoplanets which formed early in the life of the galaxy seem to have had a greater chance of developing a magnetic field and plate tectonics than planets which formed later. As both these conditions are considered favourable to the development of life, this means that if life exists in the Galaxy, it may have developed earlier than later, and that planets formed more recently may have less chance of developing life.

As lead scientist, planetary researcher Craig O'Neill said,

"Plate tectonics is important for habitability, and it looks like the optimum conditions plate tectonics existed for planets forming early in the galaxy's lifespan, and may be unlikely to easily recur. For life, maybe that was as good as it gets".

Exoplanets - planets in orbit around distant stars - have been attracting great interest because of the possibility that some of them may harbour life. Presenting the results at the Goldschmidt geochemistry conference, Professor Craig O'Neill (Director of the Macquarie Planetary Research Centre, Macquarie University) continued:

"Because of the great distances involved, we have a limited amount of information on these exoplanets, but we can understand some factors, such as position, temperature, and some idea of the geochemistry of the exoplanets. This allows us to model how they develop".

Using huge simulations involving hundreds of processors on the Australian National Computing Infrastructure, the team ran the parameters through the ASPECT* geodynamics code, which simulates the development of the interior of planets. O'Neill's group was able to show that many early planets would have tended to develop plate tectonics, which is favourable to the development of life.

He commented: "Plate tectonics act as a kind of thermostat for the Earth creating the conditions which allow life to evolve. The Earth has a lot of iron in its core, and we had assumed that this would be necessary for tectonic development. However we found that even planets with little iron may develop plate tectonics if the timing is right. This was completely unexpected".

The development of plate tectonics has a major knock-on effect. "Planets which formed later may not have developed plate tectonics, which means that they don't have this built in thermostat. This doesn't just affect the surface temperature, this means that the core stays hot, which inhibits the development of a magnetic field. If there's no magnetic field, the planet is not shielded from solar radiation, and will tend to lose its atmosphere. So life becomes difficult to sustain. A planet needs to be lucky to have the right position and the right geochemistry at the right time if it's going to sustain life", said Professor O'Neill.

Researchers know that the overall chemical balance of the Galaxy has changed over time for diverse reasons, such as material coalescing into stars and planetary bodies, or being expelled through supernova. This means that the interstellar material available to form planets is significantly different to that available in the early galaxy.

"So the planets which formed earlier did so in conditions favourable to allow the development of life" said Craig O'Neill, "These conditions are becoming increasingly rarer in our galaxy."

Commenting, Professor Sara Russell said:

"Over the last few years, amazing projects such as the NASA Kepler mission have located thousands of planets orbiting around other stars. However, these exoplanet observations alone provide very basic information. It is so important to combine observing campaigns with large simulation projects like this, that really tell us something about the geological evolution of planets formed at different stages of galactic evolution. This enables us to build a picture of what these strange worlds might look like, and how habitable they may be".

Sara Russell is a member of the Scientific Committee of the Geochemical Society. She is Professor of Planetary Sciences and leader of the Planetary Materials Group at the Natural History Museum, London. She was not involved in this work, this is an independent comment.

As of 5th June, NASA has confirmed the detection of 4158 exoplanets in our galaxy, see https://exoplanets.nasa.gov/ . The closest exoplanets yet found orbit the star Proxima Centuri, which is about 4 light years from Earth (latest data indicates either 2 or 3 exoplanets).

The Goldschmidt conference is the world's main geochemistry conference, hosted by the Geochemical Society and the European Association of Geochemistry. Held annually, it covers such material as climate change, astrobiology, planetary and stellar development and conditions, chemistry of Earth materials, pollution, the undersea environment, volcanoes, and many other subjects. For 2020 the scheduled Hawaii congress has been moved online, and takes place from 21-26 June, see https://goldschmidt.info/2020/index. Future congresses are in Lyon, France (2021) and the rescheduled Hawaii congress (2022).

*NOTE: See Advanced Solver for Problems in Earth's ConvecTion https://aspect.geodynamics.org/ ASPECT was developed by the University of California (Davis) with funding from the National Science Foundation.

In the wild, chimpanzees are more motivated to cooperate than bonobos

When informing about a threat territorial chimpanzees are more motivated to cooperate than less territorial bonobos

MAX PLANCK INSTITUTE FOR EVOLUTIONARY ANTHROPOLOGY

IMAGE: CHIMPANZEES ARRIVING LATER AT THE SNAKE WERE BETTER INFORMED AND THEREFORE LESS SURPRISED TO SEE IT IN THIS PLACE THAN BONOBOS ARRIVING LATER. view more

CREDIT: CÉDRIC GIRARD-BUTTOZ, TAÏ CHIMPANZEE PROJECT

We humans have unique cooperative systems allowing us to cooperate in large numbers. Furthermore, we provide help to others, even outside the family unit. How we developed these cooperative abilities and helping behaviour during our evolutionary past remains highly debated. According to one prominent theory, the interdependence hypothesis, the cognitive skills underlying unique human cooperative abilities evolved when several individuals needed to coordinate their actions to achieve a common goal, for example when hunting large prey or during conflict with other groups. This hypothesis also predicts that humans who rely more on each other to achieve such goals, will be more likely to provide help and support to one another in other situations.

"While we cannot study the behaviour of our human ancestors", explains Roman Wittig, a senior author and head of the Taï Chimpanzee Project, "we can learn how relying on others may influence helping behaviour in our ancestors by studying our closest living relatives, chimpanzees and bonobos". Chimpanzees are more territorial than bonobos and in some populations engage more frequently in group hunts. According to the interdependence hypothesis, chimpanzees should thus have evolved a higher tendency to cooperate and help others in the group.

To test this hypothesis, researchers from the Max Planck Institute for Evolutionary Anthropology, Harvard University and Liverpool John Moores University, presented 82 chimpanzees and bonobos from five different communities with a model of a Gaboon viper, a deadly snake. During the experiment the apes could cooperate with each other by producing alarm calls to inform conspecifics about the snake. This represents the first experimental study ever conducted in wild bonobos. "This experimental study is a novel and promising approach to probe bonobo's mind," says Gottfried Hohmann, a senior author on the study and head of the LuiKotale bonobo project. Martin Surbeck, co-author on the paper adds: "This study should stimulate several more experimental studies on wild bonobo cooperation, cognition, and communication".

In this study, researchers show that both chimpanzees and bonobos can assess what others know, as they stopped calling when all individuals around had seen the snake. However, chimpanzees warned each other more efficiently: individuals arriving later at the snake were less surprised upon seeing it than late arriving bonobos. This suggests chimpanzees were better informed of the snake's presence than bonobos. Indeed, late arriving chimpanzees were more likely to hear a call before reaching the snake than bonobos in the same circumstance, suggesting that the motivation to help and warn others was higher in chimpanzees.

"Our findings support the theory that the extreme reliance on each other in humans, for instance during war and group hunting, may have promoted the evolution of some forms of help and support to others, even sometimes to complete strangers," says first author Cédric Girard-Buttoz. The authors confirm that chimpanzees may have some awareness of others' knowledge and demonstrate for the first time this ability in wild bonobos.

"How chimpanzees and bonobos apparently keep track of other's knowledge, the specific cognitive skills to do this, are not clear," adds Catherine Crockford, last author of the study, "we face a major challenge to understand which cognitive skills are unique to humans and which are shared with other apes".

Humans navigate with stereo olfaction

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

YOU GOTTA LOVE A SCIENCE ARTICLE THAT BEGINS BY QUOTING GANDALF THE GREY

IMAGE: NOSE GUIDES HUMAN NAVIGATION. view more

CREDIT: YE YUTING

"If in doubt, always follow your nose," said Gandalf in The Lord of the Rings.

Despite Gandalf's advice, humans tend to regard themselves as "microsmatic" - having a poor sense of smell. Human navigation is thought to rely primarily on vision and audition. Specifically, subtle differences between the inputs to the paired eyes and ears are exploited by the brain to construct three-dimensional experiences that guide navigation.

Although humans also have two separate nasal passages that simultaneously sample from nonoverlapping regions in space, it is widely held that inter-nostril differences in odor concentration do not provide directional information in humans unless that odor also stimulates the trigeminal nerve (i.e., elicits hot, cold, spicy, tingling, or electric feelings), in which case it is really the trigeminal system that generates a directional cue.

However, a new study conducted by graduate student WU Yuli and his colleagues at the Institute of Psychology of the Chinese Academy of Sciences (CAS) argues otherwise.

WU and his colleagues introduced various levels of binaral concentration disparity to a heading judgment paradigm based on optic flow - a unique type of visual stimulus that captures the pattern of apparent motion of surface elements in a visual scene and induces the illusory feeling of self-movement in stationary observers.

The odorants they used were phenylethyl alcohol and vanillin, which smell like rose and vanilla, respectively, and are known to activate only the olfactory nerve.

Results from stringent psychophysical testing in four experiments involving a total of 180 participants consistently showed that a moderate binaral disparity biases recipients' perceived direction of self-motion toward the higher-concentration side in manners reminiscent of stereo vision (i.e., binocular stereopsis), despite not being able to verbalize which nostril smells a stronger odor.

In addition, the effect depends on the inter-nostril ratio of odor concentrations as opposed to the numeric difference in concentration between the two nostrils.

"Our work presents clear behavioral evidence that humans have a stereo sense of smell that subconsciously guides navigation," said Dr. ZHOU Wen, senior author of the study. "The findings underscore the multisensory nature of heading perception and could provide guidance for the design and development of olfactory virtual-reality systems for humans."

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The study, entitled "Humans navigate with stereo olfaction," was published online on PNAS on June 22.

It was funded by the Key Research Program of Frontier Sciences and the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China, and the Beijing Municipal Science and Technology Commi

Infant' planet discovered by UH astronomers, Maunakea telescope

UNIVERSITY OF HAWAII AT MANOA

IMAGE: ILLUSTRATION OF AU MIC B ORBITING ITS PARENT STAR, AU MIC. view more

CREDIT: NASA'S GODDARD SPACE FLIGHT CENTER/CHRIS SMITH (USRA)

Astronomers study stars and planets much younger than the Sun to learn about past events that shaped the Solar System and Earth. Most of these stars are far enough away to make observations challenging, even with the largest telescopes. But now this is changing.

University of Hawai'i at Mānoa astronomers are part of an international team that recently discovered an infant planet around a nearby young star. The discovery was reported Wednesday in the international journal Nature.

The planet is about the size of Neptune, but, unlike Neptune, it is much closer to its star, taking only eight and a half days to complete one orbit. It is named "AU Mic b" after its host star, AU Microscopii, or "AU Mic" for short. The planet was discovered using the NASA TESS planet-finding satellite, as it periodically passed in front of AU Mic, blocking a small fraction of its light. The signal was confirmed by observations with another NASA satellite, the Spitzer Space Telescope, and with the NASA Infrared Telescope Facility (IRTF) on Maunakea. The observations on Hawai'i Island used a new instrument called iSHELL that can make very precise measurements of the motion of a star like AU Mic. These measurements revealed a slight wobble of the star, as it moves in response to the gravitational pull of the planet. It confirmed that AU Mic b was a planet and not a companion star, which would cause a much larger motion.

Discovery on Maunakea sets foundation

AU Mic and its planet are about 25 million years young, and in their infancy, astronomically speaking. AU Mic is also the second closest young star to Earth. It is so young that dust and debris left over from its formation still orbit around it. The debris collides and breaks into smaller dust particles, which orbit the star in a thin disk. This disk was detected in 2003 with the UH 88-inch telescope on Maunakea. The newly-discovered planet orbits within a cleared-out region inside the disk.

"This is an exciting discovery, especially as the planet is in one of the most well-known young star systems, and the second-closest to Earth. In addition to the debris disk, there is always the possibility of additional planets around this star. AU Mic could be the gift that keeps on giving," said Michael Bottom, an Assistant Astronomer at the UH Institute for Astronomy.

"Planets, like people, change as they mature. For planets this means that their orbits can move and the compositions of their atmospheres can change. Some planets form hot and cool down, and unlike people, they would become smaller over time. But we need observations to test these ideas and planets like AU Mic b are an exceptional opportunity," said Astronomer Eric Gaidos, a professor in the Department of Earth Sciences at UH Mānoa.

Clues to the origin of Earth-like planets

AU Mic is not only much younger than the Sun, it is considerably smaller, dimmer and redder. It is a "red dwarf," the most numerous type of star in the galaxy. The TESS satellite is also discovering Earth-sized and possibly habitable planets around older red dwarfs, and what astronomers learn from AU Mic and AU Mic b can be applied to understand the history of those planets.

"AU Mic b, and any kindred planets that are discovered in the future, will be intensely studied to understand how planets form and evolve. Fortuitously, this star and its planet are on our cosmic doorstep. We do not have to venture very far to see the show," Gaidos explained. He is a co-author on another five forthcoming scientific publications that have used other telescopes, including several on Maunakea, to learn more about AU Mic and its planet.

AU Mic appears low in the summer skies of Hawai'i but you'll need binoculars to see it. Despite its proximity, the fact that it is a dim red star means it is too faint to be seen with the unaided eye.

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Agricultural fires in central Africa light up in Suomi NPP satellite image

NASA/GODDARD SPACE FLIGHT CENTER

IMAGE: FIRES HAVE SPREAD ACROSS THE MAJORITY OF THE LANDSCAPE IN ANGOLA AND THE DEMOCRATIC REPUBLIC OF THE CONGO IN THIS NOAA/NASA SUOMI NPP SATELLITE IMAGE USING THE VIIRS (VISIBLE INFRARED... view more

CREDIT: NASA IMAGE COURTESY WORLDVIEW EARTH DATA OPERATED BY THE NASA/GODDARD SPACE FLIGHT CENTER EARTH SCIENCE DATA AND INFORMATION SYSTEM (EOSDIS) PROJECT. CAPTION BY LYNN JENNER WITH INFORMATION FROM GLOBAL FOREST...

Fires have spread across the majority of the landscape in Angola and the Democratic Republic of the Congo in this NOAA/NASA Suomi NPP satellite image using the VIIRS (Visible Infrared Imaging Radiometer Suite) instrument from June 25, 2020. Fires of this number are not uncommon at this time of year in Africa. During the agricultural season of clearing field and planting new ones, farmers set fire to the remains of old crop fields to rid them of the leftover grasses and scrub. This action also helps return nutrients to the soil to ensure a good crop during the next planting season. This agricultural ritual is one that is at least 12,000 years ago. It is economical for the farmer since large equipment is not needed to clear the fields. In Angola, the Global Forest Watch website (using data from the VIIRS instrument on the Suomi NPP satellite) had 61,661 alerts for fires for the past week (June 18 - June 25). In the Democratic Republic of the Congo there are 102,738 VIIRS alerts for fire for that same period.

"Slash and burn" agriculture is practiced most often in regions including parts of Africa, northern South America, and Southeast Asia, where an abundance of grasslands and rainforests are found. While fire helps enhance crops and grasses for pasture, the fires also produce smoke that degrades air quality. The smoke released by any type of fire (forest, brush, crop, structure, tires, waste or wood burning) is a mixture of particles and chemicals produced by incomplete burning of carbon-containing materials. All smoke contains carbon monoxide, carbon dioxide and particulate matter or soot and is hazardous to breathe.

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NASA image courtesy Worldview Earth Data operated by the NASA/Goddard Space Flight Center Earth Science Data and Information System (EOSDIS) project. Caption by Lynn Jenner with information from Global Forest Watch.

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