What microscopic fossilized shells tell us about ancient climate change

At the end of the Paleocene and beginning of the Eocene epochs, between 59 to 51 million years ago, Earth experienced dramatic warming periods, both gradual periods stretching millions of years and sudden warming events known as hyperthermals.

Driving this planetary heat up were massive emissions of carbon dioxide (CO2) and other greenhouse gases, but other factors like tectonic activity may have also been at play.

New research led by University of Utah geoscientists pairs sea surface temperatures with levels of atmospheric CO2 during this period, showing the two were closely linked. The findings also provide case studies to test carbon cycle feedback mechanisms and sensitivities critical for predicting anthropogenic climate change as we continue pouring greenhouse gases into the atmosphere on an unprecedented scale in the planet's history.

"The main reason we are interested in these global carbon release events is because they can provide analogs for future change," said lead author Dustin Harper, a postdoctoral researcher in the Department of Geology & Geophysics. "We really don't have a perfect analog event with the exact same background conditions and rate of carbon release."

But the study published Monday in the Proceedings of the National Academy of Sciences, or PNAS, suggests emissions during two ancient "thermal maxima" are similar enough with today's anthropogenic climate change to help scientists forecast its consequences.

The research team analyzed microscopic fossils -- recovered in drilling cores taken from an undersea plateau in the Pacific -- to characterize surface ocean chemistry at the time the shelled creatures were alive. Using a sophisticated statistical model, they reconstructed sea surface temperatures and atmospheric CO2 levels over a 6-million-year period that covered two hyperthermals, the Paleocene-Eocene Thermal Maximum, or PETM, 56 million years ago and Eocene Thermal Maximum 2, ETM-2, 54 million years ago.

The findings indicate that as atmospheric levels of CO2 rose, so too did global temperatures.

"We have multiple ways that our planet, that our atmosphere is being influenced by CO2 additions, but in each case, regardless of the source of CO2, we're seeing similar impacts on the climate system," said co-author Gabriel Bowen, a U professor of geology & geophysics.

"We're interested in how sensitive the climate system was to these changes in CO2. And what we see in this study is that there's some variation, maybe a little lower sensitivity, a lower warming associated with a given amount of CO2 change when we look at these very long-term shifts. But that overall, we see a common range of climate sensitivities."

Today, human activities associated with fossil fuels are releasing carbon 4 to 10 times more rapidly than occurred during these ancient hyperthermal events. However, the total amount of carbon released during the ancient events is similar to the range projected for human emissions, potentially giving researchers a glimpse of what could be in store for us and future generations.

First scientists must determine what happened to the climate and oceans during these episodes of planetary heating more than 50 million years ago.

"These events might represent a mid- to worst-case scenario kind of case study," Harper said. "We can investigate them to answer what's the environmental change that happens due to this carbon release?"

Earth was very warm during the PETM. No ice sheets covered the poles and ocean temperatures in the mid-90s degrees Fahrenheit.

To determine oceanic CO2 levels the researchers turned to fossilized remains of foraminifera, a shelled single-cell organism akin to plankton. The research team based the study on cores previously extracted by the International Ocean Discovery Program at two locations in Pacific.

The foram shells accumulate small amounts of boron, the isotopes of which are a proxy reflecting CO2 concentrations in the ocean at the time the shells formed, according to Harper.

"We measured the boron chemistry of the shells, and we're able to translate those values using modern observations to past seawater conditions. We can get at seawater CO2 and translate that into atmospheric CO2," Harper said. "The goal of the target study interval was to establish some new CO2 and temperature records for the PETM and ETM-2, which represent two of the best analogs in terms of modern change, and also provide a longer-term background assessment of the climate system to better contextualize those events."

The cores Harper studied were extracted from Shatsky Rise in the subtropical North Pacific, which is an ideal location for recovering ocean-bottom sediments that reflect conditions in the ancient past.

Carbonate shells dissolve if they settle into deep ocean, so scientists must look to underwater plateaus like Shatsky Rise, where the water depths are relatively shallow. While their inhabitants were living millions of years ago, the foraminifera shells record the sea surface conditions.

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Study shows reduced inflammation in residents after adding trees to their neighborhoods

The University of Louisville's groundbreaking Green Heart Louisville Project has found that people living in neighborhoods where the number of trees and shrubs was more than doubled showed lower levels of a blood marker of inflammation than those living outside the planted areas. General inflammation is an important risk indicator for heart disease and other chronic diseases.

The Christina Lee Brown Envirome Institute launched the first-of-its-kind project in 2018 in partnership with The Nature Conservancy, Washington University in St. Louis, Hyphae Design Laboratory and others to study whether and how living among more densely greened surroundings contributes to better heart health. The design of the study closely mirrors clinical trials which test whether medical treatments are effective. The team applied the treatment -- the addition of large trees and shrubs -- to some participants' neighborhoods but not to others. They then compared residents' health data to see how the addition of the trees affected their health.

"The Green Heart Louisville Project is an excellent example of how our university's innovative and collaborative researchers are working to improve lives in our community and far beyond," UofL President Kim Schatzel said. "Trees are beautiful, but these results show that the trees around us are also beneficial to individual and community health. Through this and many other projects, the Envirome Institute is improving health at the community level, not just for individuals, but for everyone living in a neighborhood."

To understand the state of community's health at the start of the study, researchers took blood, urine, hair and nail samples and documented health data from 745 people living in a four-square-mile area of south Louisville. The researchers also took detailed measurements of tree coverage and levels of air pollution in the area.

Following this baseline data collection, the Envirome Institute worked with The Nature Conservancy and a host of local partners and contractors to plant more than 8,000 large trees and shrubs in designated neighborhoods within the project area. Those living in the greened area were considered the treated population and the results obtained from this population were compared with residents of adjacent neighborhoods, where the project team did not plant any trees.

After the plantings, the research team reassessed residents' health. They found that those living in the greened area had 13-20% lower levels of a biomarker of general inflammation, a measure called high-sensitivity C-reactive protein (hsCRP) than those living in the areas that did not receive any new trees or shrubs. Higher levels of hsCRP are strongly associated with a risk of cardiovascular disease and are an even stronger indicator of heart attack than cholesterol levels. Higher CRP levels also indicate a higher risk of diabetes and certain cancers.

A reduction of hsCRP by this percentage corresponds to nearly 10-15% reduction in the risk of heart attacks, cancer or dying from any disease.

"These results from the Green Heart Louisville Project indicate that trees contribute more to our lives than beauty and shade. They can improve the health of the people living around them," said Aruni Bhatnagar, director of the Envirome Institute and UofL professor of medicine. "Although several previous studies have found an association between living in areas of high surrounding greenness and health, this is the first study to show that a deliberate increase in greenness in the neighborhood can improve health. With these results and additional studies that we hope to report soon, we are closer to understanding the impact of local tree cover on residents' health. This finding will bolster the push to increase urban greenspaces."

As more is known about the health impacts of increased tree cover, increased greening in cities may emerge as a key method to improve public health.

"Most of us intuitively understand that nature is good for our health. But scientific research testing, verifying and evaluating this connection is rare," said Katharine Hayhoe, chief scientist of The Nature Conservancy. "These recent findings from the Green Heart Project build the scientific case for the powerful connections between the health of our planet and the health of all of us."

Earlier in August, the Green Heart Louisville Project was awarded an additional $4.6 million in funding from the National Institute of Environmental Health Sciences to support continued research over the next five years.

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Discovery of how blood clots harm brain and body in COVID-19 points to new therapy

In a study that reshapes what we know about COVID-19 and its most perplexing symptoms, scientists have discovered that the blood coagulation protein fibrin causes the unusual clotting and inflammation that have become hallmarks of the disease, while also suppressing the body's ability to clear the virus.

Importantly, the team also identified a new antibody therapy to combat all of these deleterious effects.

Published in Nature, the study by Gladstone Institutes and collaborators overturns the prevailing theory that blood clotting is merely a consequence of inflammation in COVID-19. Through experiments in the lab and with mice, the researchers show that blood clotting is instead a primary effect, driving other problems -- including toxic inflammation, impaired viral clearance, and neurological symptoms prevalent in those with COVID-19 and long COVID.

The trigger is fibrin, a protein in the blood that normally enables healthy blood coagulation, but has previously been shown to have toxic inflammatory effects. In the new study, scientists found that fibrin becomes even more toxic in COVID-19 as it binds to both the virus and immune cells, creating unusual clots that lead to inflammation, fibrosis, and loss of neurons.

"Knowing that fibrin is the instigator of inflammation and neurological symptoms, we can build a new path forward for treating the disease at the root," says Katerina Akassoglou, PhD, a senior investigator at Gladstone and the director of the Center for Neurovascular Brain Immunology at Gladstone and UC San Francisco. "In our experiments in mice, neutralizing blood toxicity with fibrin antibody therapy can protect the brain and body after COVID infection."

From the earliest months of the pandemic, irregular blood clotting and stroke emerged as puzzling effects of COVID-19, even among patients who were otherwise asymptomatic. Later, as long COVID became a major public health issue, the stakes grew even higher to understand the cause of this disease's other symptoms, including its neurological effects. More than 400 million people worldwide have had long COVID since the start of the pandemic, with an estimated economic cost of about $1 trillion each year.

Flipping the Conversation

Many scientists and medical professionals have hypothesized that inflammation from the immune system's rapid reaction to the COVID-causing virus is what leads to blood clotting and stroke. But even at the dawn of the pandemic in 2020, that explanation didn't sound right to Akassoglou and her scientific collaborators.

"We know of many other viruses that unleash a similar cytokine storm in response to infection, but without causing blood clotting activity like we see with COVID," says Warner Greene, MD, PhD, senior investigator and director emeritus at Gladstone, who co-led the study with Akassoglou.

"We began to wonder if blood clots played a principal role in COVID -- if this virus evolved in a way to hijack clotting for its own benefit," Akassoglou adds.

Indeed, through multiple experiments in mice, the researchers found that the virus spike protein directly binds to fibrin, causing structurally abnormal blood clots with enhanced inflammatory activity. The team leveraged genetic tools to create a specific mutation that blocks only the inflammatory properties of fibrin without affecting the protein's beneficial blood-clotting abilities.

When mice were genetically altered to carry the mutant fibrin or had no fibrin in their bloodstream, the scientists found that inflammation, oxidative stress, fibrosis, and clotting in the lungs didn't occur or were much reduced after COVID-19 infection.

In addition to discovering that fibrin sets off inflammation, the team made another important discovery: fibrin also suppresses the body's "natural killer," or NK, cells, which normally work to clear the virus from the body. Remarkably, when the scientists depleted fibrin in the mice, NK cells were able to clear the virus.

These findings support that fibrin is necessary for the virus to harm the body.

Mechanism Not Triggered by Vaccines

The fibrin mechanism described in the paper is not related to the extremely rare thrombotic complication with low platelets that has been linked to adenoviral DNA COVID-19 vaccines, which are no longer available in the U.S.

By contrast, in a study of 99 million COVID-vaccinated individuals led by The Global COVID Vaccine Safety Project, vaccines that leverage mRNA technology to produce spike proteins in the body exhibited no excessive clotting or blood-based disorders that met the threshold for safety concerns. Instead, mRNA vaccines protect from clotting complications otherwise induced by infection.

Protecting the Brain

Akassoglou's lab has long investigated how fibrin that leaks into the brain triggers neurologic diseases, such as Alzheimer's disease and multiple sclerosis, essentially by hijacking the brain's immune system and setting off a cascade of harmful, often irreversible, effects.

The team now showed that in COVID-infected mice, fibrin is responsible for the harmful activation of microglia, the brain's immune cells involved in neurodegeneration. After infection, the scientists found fibrin together with toxic microglia and when they inhibited fibrin, the activation of these toxic cells in the brains of mice was significantly reduced.

"Fibrin that leaks into the brain may be the culprit for COVID-19 and long COVID patients with neurologic symptoms, including brain fog and difficulty concentrating," Akassoglou says. "Inhibiting fibrin protects neurons from harmful inflammation after COVID-19 infection."

The team tested its approach on different strains of the virus that causes COVID-19, including those that can infect the brain and those that do not. Neutralizing fibrin was beneficial in both types of infection, pointing to the harmful role of fibrin in brain and body in COVID-19 and highlighting the broad implications of this study.

A New Potential Therapy

This study demonstrates that fibrin is damaging in at least two ways: by activating a chronic form of inflammation and by suppressing a beneficial NK cell response capable of clearing virally infected cells.

"We realized if we could neutralize both of these negative effects, we could potentially resolve the severe symptoms we're seeing in patients with COVID-19 and possibly long COVID," Greene says.

Akassoglou's lab previously developed a drug, a therapeutic monoclonal antibody, that acts only on fibrin's inflammatory properties without adverse effects on blood coagulation and protects mice from multiple sclerosis and Alzheimer's disease.

In the new study, the team showed that the antibody blocked the interaction of fibrin with immune cells and the virus. By administering the immunotherapy to infected mice, the team was able to prevent and treat severe inflammation, reduce fibrosis and viral proteins in the lungs, and improve survival rates. In the brain, the fibrin antibody therapy reduced harmful inflammation and increased survival of neurons in mice after infection.

A humanized version of Akassoglou's first-in-class fibrin-targeting immunotherapy is already in Phase 1 safety and tolerability clinical trials in healthy people by Therini Bio. The drug cannot be used on patients until it completes this Phase 1 safety evaluation, and then would need to be tested in more advanced trials for COVID-19 and long COVID.

Looking ahead to such trials, Akassoglou says patients could be selected based on levels of fibrin products in their blood -- a measure believed to be a predictive biomarker of cognitive impairment in long COVID.

"The fibrin immunotherapy can be tested as part of a multipronged approach, along with prevention and vaccination, to reduce adverse health outcomes from long COVID," Greene adds.

The Power of Team Science

The study's findings intersect the scientific areas of immunology, hematology, virology, neuroscience, and drug discovery -- and required many labs across institutions to work together to execute experiments required to solve the blood-clotting mystery. Akassoglou founded the Center for Neurovascular Brain Immunology at Gladstone and UCSF in 2021 specifically for the purpose of conducting multidisciplinary, collaborative studies that address complex problems.

"I don't think any single lab could have accomplished this on their own," says Melanie Ott, MD, PhD, director of the Gladstone Institute of Virology and co-author of the study, noting important contributions from teams at Stanford, UC San Francisco, UC San Diego, and UCLA. "This tour-de-force study highlights the importance of collaboration in tackling these big questions."

Not only did this study address a big question, but it did so in a way that paves a clear clinical path for helping patients who have few options today, says Lennart Mucke, MD, director of the Gladstone Institute of Neurological Disease.

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Hidden magmatism discovered at the Chang'e-6 lunar landing site

Lunar igneous activities including intrusive and extrusive magmatism, and their products contain significant information about the lunar interior and its thermal state. Their distribution is asymmetrical on the nearside and farside, reflecting the global lunar dichotomy. In addition to previously returned lunar samples all from nearside (Apollo, Luna, and Chang'e-5), samples from the South Pole-Aitken (SPA) basin on the farside have long been thought to hold the key to rebalancing the asymmetrical understandings of the Moon and disclosing the lunar dichotomy conundrum.

Earlier this year, the Chang'e-6 mission of the Chinese Lunar Exploration Program, successfully launched on May 3, landed on the lunar surface on June 2, and returned to the Earth on June 25 carrying a total of 1935.3g of lunar soils. It is the world's first lunar farside sample-return mission, which landed in the south of the Apollo basin within the SPA basin on the farside. These precious samples would open a window to solve the long-standing question of lunar dichotomy, even reshape human's knowledge of our closest neighbour. However, compared with the well-known mare volcanism surrounding the Chang'e-6 landing site, the intrusive magmatic activities have a much more obscure presence and origin, impeding future sample analyses when they are available for application.

In a recent research paper published in The Astrophysical Journal Letters, Dr Yuqi QIAN, Professor Joseph MICHALSKI and Professor Guochun ZHAO from the Department of Earth Sciences at The University of Hong Kong (HKU) and their domestic and international collaborators have comprehensively studied the intrusive magmatism of the Chang'e-6 landing site and its surroundings based on remote sensing data. The study revealed their extensive distributions and obscure nature with significant implications for the petrogenesis of lunar plutonic rocks and the Chang'e-6 mission, which will facilitate scientists' further study of lunar farside.

The study has found that intrusive magmatism is widespread in the SPA basin. They occur in various forms including sills beneath floor-modified craters, linear and ring dikes shown by gravity data, and Mg-suite intrusions with characteristic spectral absorptions. These observations agree with the intermediate-thick crust of SPA where intrusion is favored. Landing in the SPA basin, Chang'e-6 likely collected plutonic rocks, excavated and transported by adjacent impact craters to the sampling site, that could be examined by the ongoing sample studies. They have discovered two heavily degraded floor-fractured craters, inspiring to identify more similar features on the Moon. All indicate that intrusive magmatism is abundant in the Chang'e-6 sampling region.

This study has traced potential plutonic materials in the Chang'e-6 samples and found that Mg-suite materials highly likely exist, primarily from the western peak ring of the Apollo basin delivered by Chaffee S crater. These Mg-rich materials contain crucial information on the origin of mysterious KREEP-poor Mg-suite rocks. Samples from both the intrusive and extrusive magmatism from the never sampled farside, especially the mysterious Mg-suite, will shed further light on solving the lunar dichotomy conundrum and a series of fundamental scientific questions relating to secondary crust building and early evolution of the Moon.

Professor Xianhua LI, an academician of the Chinese Academy of Science (CAS), and a leader of China's lunar sample studies from the Institute of Geology and Geophysics (CAS), said: 'The results of this research set a significant geological framework to study plutonic rocks in the Chang'e-6 samples, especially Mg-suite rocks.' Professor Li emphasised: 'Their petrogenesis and timing are unclear, and this research would dramatically help to understand their origin mechanism.'

'This research is an excellent example of HKU's deep involvement in the China's Lunar Exploration Program,' said Professor Guochun ZHAO, an academician of the Chinese Academy of Science and Chair Professor of Earth Sciences (HKU). 'Lunar and space exploration programs are an important component of China's goal to become a scientific and technological power, and HKU's proactive involvement in these programs will bring additional resources for Hong Kong to become an international centre for science and innovation,' he continued.

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Coastal cities must adapt faster to climate change

Coastal cities play a key role in the global economy and have important functions for society at large. At the same time, they are severely affected by the impact of climate change. That is why their role in global climate adaptation is crucial. To find out how coastal cities are adapting, an international team led by Professor Matthias Garschagen, a geographer at Ludwig-Maximilians-Universität München (LMU), has now analyzed the current state of adaptation.

Based on studies of 199 cities across 54 countries, the researchers investigated whether and how cities take certain risk factors into account in their adaptation efforts. Climate factors like rising sea levels, storms, flooding and heat were among the key parameters considered. Other aspects were also taken into account in the analysis, such as the exposure and vulnerability of the population, the infrastructure and the ecosystems in the respective region.

Climate measures are mostly inadequate

Most of the measures taken to adapt to climate change relate primarily to sea level rise, flooding and, to a lesser extent, storm surges, cyclones and erosion. Technical and institutional measures such as large-scale levees or urban planning innovations are more common in wealthier regions like North America and Europe. In less prosperous regions such as in many parts of Africa and Asia, behavior-related measures are the dominant type, with affected households and companies being largely left to their own devices.

Overall, the LMU researchers found that most adaptation measures are inadequate in their depth, scope and speed -- regardless of the region or its prosperity. The researchers also found little evidence of a sustainable reduction in risk as a result of the measures taken.

"Our findings reveal that there is plenty of work still to be done on all levels," explains Prof. Matthias Garschagen. "There has been little truly far-reaching change involving a fundamental rethink of risk management. Cities often attempt to optimize their disaster management on the basis of past experience without fundamentally questioning whether these approaches are still going to be viable in the future," says Garschagen.

Global research on climate change needs to be done in all regions of the world

The research also found that it is rare for adaptation planning to be based on quantifiable factors. Although cities do take future natural risks such as flooding and heat into account, they rarely consider socioeconomic factors such as future trends in societal vulnerability or spatial growth and exposure. "But those trends those are important," says Garschagen, "because the Lagos or Jakarta of today is not the same as it's going to be in 20 years' time. There are certainly big research aps and we need better scenarios and better modeling methods. Another important question is about when it makes more sense to abandon coastal protection measures and consider resettling the population instead."

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Public trust in drinking water safety is low globally

A new study finds more than half of adults surveyed worldwide expect to be seriously harmed by their water within the next two years. Led by global health experts at Northwestern University and the University of North Carolina at Chapel Hill, the study sought to understand public perceptions of drinking water safety.

Because perceptions shape attitudes and behaviors, distrust in water quality has a negative impact on people's health, nutrition, psychological and economic well-being -- even when the water meets safety standards.

"If we think our water is unsafe, we will avoid using it," said Sera Young, professor of anthropology and global health at Northwestern and senior author of the new study.

"When we mistrust our tap water, we buy packaged water, which is wildly expensive and hard on the environment; drink soda or other sugar-sweetened beverages, which is hard on the teeth and the waistline; and consume highly processed prepared foods or go to restaurants to avoid cooking at home, which is less healthy and more expensive," Young said. "Individuals exposed to unsafe water also experience greater psychological stress and are at greater risk of depression."

Young is a Morton O. Schapiro Faculty Fellow at the Institute for Policy Research, a faculty fellow at the Paula M. Trienens Institute for Sustainability and Energy, and co-lead of the Making Water Insecurity Visible Working Group at the Buffett Institute for Global Affairs.

Using nationally representative data from 148,585 adults in 141 countries from the 2019 Lloyd's Register Foundation World Risk Poll, the authors found a high prevalence of anticipated harm from water supply, with the highest in Zambia, the lowest in Singapore and an overall mean of 52.3%.

They also identified key characteristics of those who thought they would be harmed by their drinking water. Women, city dwellers, individuals with more education, and those struggling on their current income were more likely to anticipate being harmed by their drinking water.

The researchers found that, surprisingly, higher corruption perception index scores were the strongest predictor of anticipated harm from drinking water, more so than factors like infrastructure and Gross Domestic Product.

Further, even within countries with consistent access to basic drinking water services, doubts about the safety of water were widespread. This includes the U.S. where 39% of those polled anticipated serious harm from drinking water in the short term.

"Our research highlights that it is imperative both to deliver safe drinking water and to make sure that people have confidence in their water source," said Joshua Miller, a doctoral student at the UNC Gillings School of Global Public Health and the study's first author.

The researchers note that it is difficult for consumers to judge the hazards and safety of their water supply because many contaminants are invisible, odorless and tasteless. Without adequate information, many are left to evaluate the safety of their water based on prior experiences, media reports, and personal values and beliefs.

"It's also possible that people correctly judge the safety of their water," Young said. "The good people of Flint didn't trust their water and they were spot on."

The co-authors suggest actions officials can take to improve public trust around drinking water, including efforts to make testing more readily available, translate test results, replace lead pipes and provide at-home water filters when contaminants are detected, as well as provide improved access to safe drinking water.

"This is the kind of work that can catalyze greater attention and political will to prioritize these services in national development plans and strategies, and get us closer to achieving universal access to safe drinking water," said Aaron Salzberg, director of the Water Institute at the UNC Gillings School of Global Public Health.

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Matching dinosaur footprints found on opposite sides of the Atlantic Ocean

An international team of researchers led by SMU paleontologist Louis L. Jacobs has found matching sets of Early Cretaceous dinosaur footprints on what are now two different continents.

More than 260 footprints were discovered in Brazil and in Cameroon, showing where land-dwelling dinosaurs were last able to freely cross between South America and Africa millions of years ago before the two continents split apart.

"We determined that in terms of age, these footprints were similar," Jacobs said. "In their geological and plate tectonic contexts, they were also similar. In terms of their shapes, they are almost identical."

The footprints, impressed into mud and silt along ancient rivers and lakes, were found more than 3,700 miles, or 6,000 kilometers, away from each other. Dinosaurs made the tracks 120 million years ago on a single supercontinent known as Gondwana -- which broke off from the larger landmass of Pangea, Jacobs said.

"One of the youngest and narrowest geological connections between Africa and South America was the elbow of northeastern Brazil nestled against what is now the coast of Cameroon along the Gulf of Guinea," Jacobs explained. "The two continents were continuous along that narrow stretch, so that animals on either side of that connection could potentially move across it."

Most of the dinosaur fossils were created by three-toed theropod dinosaurs.. A few were also likely made by sauropods or ornithischians, said Diana P. Vineyard, who is a research associate at SMU and co-author of the study.

Other co-authors of the study were Lawrence J. Flynn in the Department of Human Evolutionary Biology at Harvard University, Christopher R. Scotese in the Department of Earth and Planetary Sciences at Northwestern University and Ismar de Souza Carvalho at the Universidade Federal do Rio de Janeiro and Centro de Geociências.

The study was published by New Mexico Museum of Natural History & Science in a tribute to the late paleontologist Martin Lockley, who spent much of his career studying dinosaurs tracks and footprints.

Dinosaur footprints tell the whole story

Africa and South America started to split around 140 million years ago, causing gashes in Earth's crust called rifts to open up along pre-existing weaknesses. As the tectonic plates beneath South America and Africa moved apart, magma from the Earth's mantle rose to the surface, creating new oceanic crust as the continents moved away from each other. And eventually, the South Atlantic Ocean filled the void between these two newly-shaped continents.

Signs of some of those major events were evident between both locations where the dinosaur footprints were found -- at the Borborema region in the northeast part of Brazil and the Koum Basin in northern Cameroon. Half-graben basins -- geologic structures formed during rifting as the Earth's crust pulls apart and faults form -- are found in both areas and contain ancient river and lake sediments. Along with dinosaur tracks, these sediments contain fossil pollen that indicate an age of 120 million years.

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NASA's DART impact permanently changed the shape and orbit of asteroid moon

When NASA's Double Asteroid Redirection Test (DART) spacecraft collided with an asteroid moon called Dimorphos in 2022, the moon was significantly deformed -- creating a large crater and reshaping it so dramatically that the moon derailed from its original evolutionary progression -- according to a new study. The study's researchers believe that Dimorphos may start to "tumble" chaotically in its attempts to move back into gravitational equilibrium with its parent asteroid named Didymos.

"For the most part, our original pre-impact predictions about how DART would change the way Didymos and its moon move in space were correct," said Derek Richardson, a professor of astronomy at the University of Maryland and a DART investigation working group lead. "But there are some unexpected findings that help provide a better picture of how asteroids and other small bodies form and evolve over time."

The paper published in Planetary Science Journal on August 23, 2024 by a team led by Richardson detailed notable post-impact observations and described possible implications for future asteroid research.

One of the biggest surprises was how much the impact with DART changed the shape of Dimorphos. According to Richardson, the asteroid moon was originally oblate (shaped like a hamburger) but became more prolate (stretched out like a football) after the DART spacecraft collided with it.

"We were expecting Dimorphos to be prolate pre-impact simply because that's generally how we believed the central body of a moon would gradually accumulate material that's been shed off a primary body like Didymos. It would naturally tend to form an elongated body that would always point its long axis toward the main body," Richardson explained. "But this result contradicts that idea and indicates that something more complex is at work here. Furthermore, the impact-induced change in Dimorphos' shape likely changed how it interacts with Didymos."

Richardson noted that although DART only hit the moon, the moon and the main body are connected through gravity. The debris scattered by the spacecraft on impact also played a role in the disturbed equilibrium between the moon and its asteroid, shortening Dimorphos' orbit around Didymos. Interestingly, Didymos' shape remained the same -- a finding that indicates that the larger asteroid's body is firm and rigid enough to maintain its form even after losing mass to create its moon.

According to Richardson, Dimorphos' changes have important implications for future exploration efforts, including the European Space Agency's follow-up mission to the Didymos system slated for October 2024.

"Originally, Dimorphos was probably in a very relaxed state and had one side pointing toward the main body, Didymos, just like how Earth's moon always has one face pointing toward our planet," Richardson explained. "Now, it's knocked out of alignment, which means it may wobble back and forth in its orientation. Dimorphos might also be 'tumbling,' meaning that we may have caused it to rotate chaotically and unpredictably."

The team is now waiting to find out when the ejected debris will clear from the system, whether Dimorphos is still tumbling in space and when it will eventually regain its previous stability.

"One of our biggest questions now is if Dimorphos is stable enough for spacecraft to land and install more research equipment on it," he said. "It could take a hundred years to see noticeable changes in the system, but it's only been a few years since the impact. Learning about how long it takes Dimorphos to regain its stability tells us important things about its internal structure, which in turn informs future attempts to deflect hazardous asteroids."

Richardson and his team hope that Hera will provide more information about DART's impact. By late 2026, Hera will arrive at the binary asteroid system containing Dimorphos and Didymos to assess the internal properties of both asteroids for the first time, providing a more detailed analysis of the DART mission and its implications for the future.

Read more at Science Daily

Fisheries research overestimates fish stocks

The state of fish stocks in the world's ocean is worse than previously thought. While overfishing has long been blamed on fisheries policies that set catch limits higher than scientific recommendations, a new study by four Australian research institutions reveals that even these scientific recommendations were often too optimistic. The result? Far more global fish stocks are overfished or have collapsed than we thought. Dr Rainer Froese from the GEOMAR Helmholtz Centre for Ocean Research Kiel and Dr Daniel Pauly from the University of British Columbia have provided their insights on the study. In their Perspective Paper, published today in the journal Science alongside the new study, the two fisheries experts call for simpler yet more accurate models and, when in doubt, a more conservative approach to stock assessments.

Many fish stocks around the world are either threatened by overfishing or have already collapsed. One of the main reasons for this devastating trend is that policymakers have often ignored the catch limits calculated by scientists, which were intended to be strict thresholds to protect stocks. But it has now become clear that even these scientific recommendations were often too high.

In the European Union (EU), for example, fisheries are primarily managed through allowable catch limits, known as quotas, which are set by the European Council of Agriculture Ministers on the basis of scientific advice and recommendations from the European Commission. A new study by Australian scientists (Edgar et al.) shows that already the scientific advice has been recommending catch limits that were too high.

The journal Science, where the study is published today, asked two of the world's most cited fisheries experts, Dr Rainer Froese from the GEOMAR Helmholtz Centre for Ocean Research Kiel and Dr Daniel Pauly from the University of British Columbia, to interpret the findings. In their Perspective Paper, they advocate for simpler, yet more realistic models based on ecological principles, and call for more conservative stock assessments and management when uncertainties arise.

For the study, Edgar et al. analysed data from 230 fish stocks worldwide and found that stock assessments have often been overly optimistic. They overestimated the abundance of fish and how quickly stocks could recover. Particularly affected are stocks that have already shrunk due to overfishing. The overestimates led to so-called phantom recoveries, where stocks were classified as recovered while, in reality, they continued to decline. "This resulted in insufficient reductions in catch limits when they were most urgently needed," explains Dr Rainer Froese. "Unfortunately, this is not just a problem of the past. Known overestimates of stock sizes in recent years are still not used to corrected this error in current stock assessments."

The research by Edgar et al. also shows that almost a third of stocks classified by the Food and Agriculture Organization (FAO) as "maximally sustainably fished" have instead crossed the threshold into the "overfished" category. Moreover, the number of collapsed stocks (those with less than ten per cent of their original biomass) within the overfished category is likely to be 85 per cent higher than previously estimated.

But what causes these distortions in stock assessments? Standard stock assessments use models that can include more than 40 different parameters, such as fish life history, catch details, and fishing effort. This large number of parameters makes the assessments unnecessarily complex, write Froese and Pauly. The results can only be reproduced by a few experts with access to the original models, data and settings. Moreover, many of the required input parameters are unknown or difficult to estimate, leading modelers to use less reliable values that have worked in the past. Froese notes: "Such practices can skew the results towards the modelers' expectations."

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Mosquitoes sense infrared from body heat to help track humans down

While a mosquito bite is often no more than a temporary bother, in many parts of the world it can be scary. One mosquito species, Aedes aegypti, spreads the viruses that cause over 100,000,000 cases of dengue, yellow fever, Zika and other diseases every year. Another, Anopheles gambiae, spreads the parasite that causes malaria. The World Health Organization estimates that malaria alone causes more than 400,000 deaths every year. Indeed, their capacity to transmit disease has earned mosquitoes the title of deadliest animal.

Male mosquitoes are harmless, but females need blood for egg development. It's no surprise that there's over 100 years of rigorous research on how they find their hosts. Over that time, scientists have discovered there is no one single cue that these insects rely on. Instead, they integrate information from many different senses across various distances.

A team led by researchers at UC Santa Barbara has added another sense to the mosquito's documented repertoire: infrared detection. Infrared radiation from a source roughly the temperature of human skin doubled the insects' overall host-seeking behavior when combined with CO2 and human odor. The mosquitoes overwhelmingly navigated toward this infrared source while host seeking. The researchers also discovered where this infrared detector is located and how it works on a morphological and biochemical level. The results are detailed in the journalNature.

"The mosquito we study, Aedes aegypti, is exceptionally skilled at finding human hosts," said co-lead author Nicolas DeBeaubien, a former graduate student and postdoctoral researcher at UCSB in Professor Craig Montell's laboratory. "This work sheds new light on how they achieve this."

Guided by thermal infrared

It is well established that mosquitoes like Aedes aegypti use multiple cues to home in on hosts from a distance. "These include CO2 from our exhaled breath, odors, vision, [convection] heat from our skin, and humidity from our bodies," explained co-lead author Avinash Chandel, a current postdoc at UCSB in Montell's group. "However, each of these cues have limitations." The insects have poor vision, and a strong wind or rapid movement of the human host can throw off their tracking of the chemical senses. So the authors wondered if mosquitoes could detect a more reliable directional cue, like infrared radiation.

Within about 10 cm, these insects can detect the heat rising from our skin. And they can directly sense the temperature of our skin once they land. These two senses correspond to two of the three kinds of heat transfer: convection, heat carried away by a medium like air, and conduction, heat via direct touch. But energy from heat can also travel longer distances when converted into electromagnetic waves, generally in the infrared (IR) range of the spectrum. The IR can then heat whatever it hits. Animals like pit vipers can sense thermal IR from warm prey, and the team wondered whether mosquitoes, like Aedes aegypti, could as well.

The researchers put female mosquitoes in a cage and measured their host-seeking activity in two zones. Each zone was exposed to human odors and CO2 at the same concentration that we exhale. However, only one zone was also exposed to IR from a source at skin temperature. A barrier separated the source from the chamber prevented heat exchange through conduction and convection. They then counted how many mosquitoes began probing as if they were searching for a vein.

Adding thermal IR from a 34º Celcius source (about skin temperature) doubled the insects' host-seeking activity. This makes infrared radiation a newly documented sense that mosquitoes use to locate us. And the team discovered it remains effective up to about 70 cm (2.5 feet).

"What struck me most about this work was just how strong of a cue IR ended up being," DeBeaubien said. "Once we got all the parameters just right, the results were undeniably clear."

Previous studies didn't observe any effect of thermal infrared on mosquito behavior, but senior author Craig Montell suspects this comes down to methodology. An assiduous scientist might try to isolate the effect of thermal IR on insects by only presenting an infrared signal without any other cues. "But any single cue alone doesn't stimulate host-seeking activity. It's only in the context of other cues, such as elevated CO2 and human odor that IR makes a difference," said Montell, the Duggan and Distinguished Professor of Molecular, Cellular, and Developmental Biology. In fact, his team found the same thing in tests with only IR: infrared alone has no impact.

A trick for sensing infrared

It isn't possible for mosquitoes to detect thermal infrared radiation the same way they would detect visible light. The energy of IR is far too low to activate the rhodopsin proteins that detect visible light in animal eyes. Electromagnetic radiation with a wavelength longer than about 700 nanometers won't activate rhodopsin, and IR generated from body heat is around 9,300 nm. In fact, no known protein is activated by radiation with such long wavelengths, Montell said. But there is another way to detect IR.

Consider heat emitted by the sun. The heat is converted into IR, which streams through empty space. When the IR reaches Earth, it hits atoms in the atmosphere, transferring energy and warming the planet. "You have heat converted into electromagnetic waves, which is being converted back into heat," Montell said. He noted that the IR coming from the sun has a different wavelength from the IR generated by our body heat, since the wavelength depends on the temperature of the source.

The authors thought that perhaps our body heat, which generates IR, might then hit certain neurons in the mosquito, activating them by heating them up. That would enable the mosquitoes to detect the radiation indirectly.

Scientists have known that the tips of a mosquito's antennae have heat-sensing neurons. And the team discovered that removing these tips eliminated the mosquitoes' ability to detect IR.

Indeed, another lab found the temperature-sensitive protein, TRPA1, in the end of the antenna. And the UCSB team observed that animals without a functional trpA1 gene, which codes for the protein, couldn't detect IR.

The tip of each antenna has peg-in-pit structures that are well adapted to sensing radiation. The pit shields the peg from conductive and convective heat, enabling the highly directional IR radiation to enter and warm up the structure. The mosquito then uses TRPA1 -- essentially a temperature sensor -- to detect infrared radiation.

Diving into the biochemistry

The activity of the heat-activated TRPA1 channel alone might not fully explain the range over which mosquitoes were able to detect IR. A sensor that exclusively relied on this protein may not be useful at the 70 cm range the team had observed. At this distance there likely isn't sufficient IR collected by the peg-in-pit structure to heat it enough to activate TRPA1.

Fortunately, Montell's group thought there might be more sensitive temperature receptors based on their previous work on fruit flies in 2011. They had found a few proteins in the rhodopsin family that were quite sensitive to small increases in temperature. Although rhodopsins were originally thought of exclusively as light detectors, Montell's group found that certain rhodopsins can be triggered by a variety of stimuli. They discovered that proteins in this group are quite versatile, involved not just in vision, but also in taste and temperature sensing. Upon further investigation, the researchers discovered that two of the 10 rhodopsins found in mosquitoes are expressed in the same antennal neurons as TRPA1.

Knocking out TRPA1 eliminated the mosquito's sensitivity to IR. But insects with faults in either of the rhodopsins, Op1 or Op2, were unaffected. Even knocking out both the rhodopsins together didn't entirely eliminate the animal's sensitivity to IR, although it significantly weakened the sense.

Their results indicated that more intense thermal IR -- like what a mosquito would experience at closer range (for example, around 1 foot) -- directly activates TRPA1. Meanwhile, Op1 and Op2 can get activated at lower levels of thermal IR, and then indirectly trigger TRPA1. Since our skin temperature is constant, extending the sensitivity of TRPA1 effectively extends the range of the mosquito's IR sensor to around 2.5 ft.

A tactical advantage

Half the world's population is at risk for mosquito-borne diseases, and about a billion people get infected every year, Chandel said. What's more, climate change and worldwide travel have extended the ranges of Aedes aegypti beyond tropical and subtropical countries. These mosquitoes are now present in places in the US where they were never found just a few years ago, including California.

The team's discovery could provide a way to improve methods for suppressing mosquito populations. For instance, incorporating thermal IR from sources around skin temperature could make mosquito traps more effective. The findings also help explain why loose-fitting clothing is particularly good at preventing bites. Not only does it block the mosquito from reaching our skin, it also allows the IR to dissipate between our skin and the clothing so the mosquitoes cannot detect it.

"Despite their diminutive size, mosquitoes are responsible for more human deaths than any other animal," DeBeaubien said. "Our research enhances the understanding of how mosquitoes target humans and offers new possibilities for controlling the transmission of mosquito-borne diseases."

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