Solving Everest's wildlife mysteries with eDNA

A team of scientists led by the Wildlife Conservation Society (WCS) and Appalachian State University used environmental DNA (eDNA) to document the breadth of high-alpine biodiversity present on Earth's highest mountain, 29,032-foot Mt. Everest (8,849 m).

Describing their findings in the journal iScience, the team collected eDNA from water samples over a four-week period in ten ponds and streams between 14,763 feet (4,500 meters) and 18,044 feet (5,500 meters). The sites included areas of the alpine zone that exist above the tree line and contain an array of flowering plants and shrub species, along with the aeolian zone that reaches beyond the range of flowering plants and shrubs at the uppermost reaches of the biosphere. From just 20 liters of water, they identified organisms belonging to 187 taxonomic orders, which corresponds to 16.3 percent, or one sixth, of the total known orders across the tree of life -- a family tree of Earth's biodiversity.

eDNA searches for trace amounts of genetic material left behind by organisms and wildlife and offers a more accessible, rapid, and comprehensive approach to increasing survey capacity for assessing biodiversity in aquatic environments. Samples are collected using a sealed cartridge containing a filter that captures genetic material that is later analyzed at a lab using DNA metabarcoding and other sequencing methodologies. WCS has been using eDNA for detection of rare and threatened species from humpback whales to Swinhoe's softshell turtle, one of the rarest species on the planet.

Although the Everest study focused on identification at the order level, the team was able to identify many organisms to the genus or species level.

For example, the team identified both rotifers and tardigrades, two tiny animal organisms that are known to occur in the harshest and most extreme environments and are considered to be among the most resilient animals known on Earth. In addition, they identified Tibetan snow cock, which are found in Sagarmatha National Park, and were surprised to find species such as domestic dog and chicken, representing how human activities are influencing the landscape.

They also identified pine trees, which only are found far downhill from where they sampled, demonstrating how wind-blown pollen can make its way high up into these watersheds. Another organism they identified from several sites were mayflies, which are known indicator species for environmental change.

The eDNA inventory will aid future high-Himalayan biomonitoring and retrospective molecular studies to assess changes over time as climate-driven warming, glacial melt, and human-caused influences reshape this rapidly transforming world-renowned ecosystem.

Said Dr. Tracie Seimon of WCS's Zoological Health Program, co-lead of the Everest biology field team and lead of the study: "High-alpine and aeolian environments, which have often been thought of as barren and mostly devoid of life, in fact have abundant biodiversity. High mountain environments including Mount Everest should be recognized as a target for sustained long-term biodiversity monitoring of high-alpine taxa to complement bioclimatic monitoring and climate change impact assessments."

Said Dr. Marisa Lim of the Wildlife Conservation Society: "We went in search for life on the roof of the world. This is what we found. However, the story does not end here. There is more to be discovered and we hope our findings help to inform future exploration."

Read more at Science Daily

Exercise answer: Research shows it's how often you do it, not how much

So… should I exercise a little bit every day, or exercise for longer once a week?

It's a dilemma faced by many health-conscious people -- and new research from Edith Cowan University (ECU) is answering the question.

This latest research indicates a little bit of daily activity could well be the most beneficial approach, at least for muscle strength.

And happily, it also suggests you don't have to put in a mountain of work every day.

In collaboration with Niigata University and Nishi Kyushu University in Japan, the four-week training study had three groups of participants performing an arm resistance exercise and changes in muscle strength and muscle thickness were measured and compared.

The exercise consisted of 'maximal voluntary eccentric bicep contractions' performed on a machine which measures muscle strength in each muscle contraction you would do at the gym.

An eccentric contraction is when the muscle is lengthening; in this case, like lowering a heavy dumbbell in a bicep curl.

Two groups performed 30 contractions per week, with one group doing six contractions a day for five days a week (6x5 group), while the other crammed all 30 into a single day, once a week (30x1 group).

Another group only performed six contractions one day a week.

After four weeks, the group doing 30 contractions in a single day did not show any increase in muscle strength, although muscle thickness (an indicator of increase in muscle size) increased 5.8 per cent.

The group doing six contractions once a week did not show any changes in muscle strength and muscle thickness.

However, the 6x5 group saw significant increases in muscle strength -- more than 10 per cent -- with an increase in muscle thickness similar to the 30x1 group.

Frequency, not volume

Importantly, the increase in muscle strength of the 6x5 group was similar to the group in a previous study that performed only one three-second maximal eccentric contraction per day for five days a week for four weeks.

ECU Exercise and Sports Science Professor Ken Nosaka said these studies continue to suggest very manageable amounts of exercise done regularly can have a real effect on people's strength.

"People think they have to do a lengthy session of resistance training in the gym, but that's not the case," he said.

"Just lowering a heavy dumbbell slowly once or six times a day is enough."

Professor Nosaka said while the study required participants to exert maximum effort, early findings from current, ongoing research indicated similar results could be achieved without needing to push as hard as possible.

"We only used the bicep curl exercise in this study, but we believe this would be the case for other muscles also, at least to some extent," he said.

"Muscle strength is important to our health. This could help prevent a decrease in muscle mass and strength with ageing.

"A decrease in muscle mass is a cause of many chronic disease such as cardiovascular disease, type 2 diabetes, some cancers, dementia, plus musculoskeletal problems such as osteoporosis."

Rest up

It is not yet known precisely why the body responds better to resistance exercises with eccentric contractions in smaller doses rather than bigger loads less frequently.

Professor Nosaka said it may relate to how often the brain is asked to make a muscle perform in a particular manner.

However, he stressed it was also important to include rest in an exercise regimen.

"In this study, the 6x5 group had two days off per week," he said.

"Muscle adaptions occur when we are resting; if someone was able to somehow train 24 hours a day, there would actually be no improvement at all.

"Muscles need rest to improve their strength and their muscle mass, but muscles appear to like to be stimulated more frequently."

He also highlighted if someone was unable to exercise for a period, there was no value in trying to "make up" for it with a longer session later.

"If someone's sick and can't exercise for a week, that's fine, but it is better to just return to regular exercise routine when you're feeling better" he said.

Clarifying advice

Current Australian Government guidelines already indicate adults should try to be active every day and perform 2.5-5 hours of moderate physical activity per week.

Professor Nosaka said there needed to be more emphasis on the importance of making exercise a daily activity, rather than hitting a weekly minute goal.

"If you're just going to the gym once a week, it's not as effective as doing a bit of exercise every day at home," he said.

"This research, together with our previous study, suggests the importance of accumulating a small amount of exercise a week, than just spending hours exercising once a week.

"We need to know that every muscle contraction counts, and it's how regularly you perform them that counts."

Read more at Science Daily

Today's heat waves feel a lot hotter than heat index implies

If you looked at the heat index during this summer's sticky heat waves and thought, "It sure feels hotter!," you may be right.

An analysis by climate scientists at the University of California, Berkeley, finds that the apparent temperature, or heat index, calculated by meteorologists and the National Weather Service (NWS) to indicate how hot it feels -- taking into account the humidity -- underestimates the perceived temperature for the most sweltering days we're now experiencing, sometimes by more than 20 degrees Fahrenheit.

The finding has implications for those who suffer through these heat waves, since the heat index is a measure of how the body deals with heat when the humidity is high, and sweating becomes less effective at cooling us down. Sweating and flushing, where blood is diverted to capillaries close to the skin to dissipate heat, plus shedding clothes, are the main ways humans adapt to hot temperatures.

A higher heat index means that the human body is more stressed during these heat waves than public health officials may realize, the researchers say. The NWS currently considers a heat index above 103 to be dangerous, and above 125 to be extremely dangerous.

"Most of the time, the heat index that the National Weather Service is giving you is just the right value. It's only in these extreme cases where they're getting the wrong number," said David Romps, UC Berkeley professor of earth and planetary science. "Where it matters is when you start to map the heat index back onto physiological states and you realize, oh, these people are being stressed to a condition of very elevated skin blood flow where the body is coming close to running out of tricks for compensating for this kind of heat and humidity. So, we're closer to that edge than we thought we were before."

Romps and graduate student Yi-Chuan Lu detailed their analysis in a paper accepted by the journal Environmental Research Letters and posted online Aug. 12.

The heat index was devised in 1979 by a textile physicist, Robert Steadman, who created simple equations to calculate what he called the relative "sultriness" of warm and humid, as well as hot and arid, conditions during the summer. He saw it as a complement to the wind chill factor commonly used in the winter to estimate how cold it feels.

His model took into account how humans regulate their internal temperature to achieve thermal comfort under different external conditions of temperature and humidity -- by consciously changing the thickness of clothing or unconsciously adjusting respiration, perspiration and blood flow from the body's core to the skin.

In his model, the apparent temperature under ideal conditions -- an average-sized person in the shade with unlimited water -- is how hot someone would feel if the relative humidity were at a comfortable level, which Steadman took to be a vapor pressure of 1,600 pascals.

For example, at 70% relative humidity and 68 F -- which is often taken as average humidity and temperature -- a person would feel like it's 68 F. But at the same humidity and 86 F, it would feel like 94 F.

The heat index has since been adopted widely in the United States, including by the NWS, as a useful indicator of people's comfort. But Steadman left the index undefined for many conditions that are now becoming increasingly common. For example, for a relative humidity of 80%, the heat index is not defined for temperatures above 88 F or below 59 F. Today, temperatures routinely rise above 90 F for weeks at a time in some areas, including the Midwest and Southeast.

To account for these gaps in Steadman's chart, meteorologists extrapolated into these areas to get numbers that, Romps said, are correct most of the time, but not based on any understanding of human physiology.

"There's no scientific basis for these numbers," Romps said.

He and Lu set out to extend Steadman's work so that the heat index is accurate at all temperatures and all humidities between zero and 100%.

"The original table had a very short range of temperature and humidity and then a blank region where Steadman said the human model failed," Lu said. "Steadman had the right physics. Our aim was to extend it to all temperatures so that we have a more accurate formula."

One condition under which Steadman's model breaks down is when people perspire so much that sweat pools on the skin. At that point, his model incorrectly had the relative humidity at the skin surface exceeding 100%, which is physically impossible.

"It was at that point where this model seems to break, but it's just the model telling him, hey, let sweat drip off the skin. That's all it was," Romps said. "Just let the sweat drop off the skin."

That and a few other tweaks to Steadman's equations yielded an extended heat index that agrees with the old heat index 99.99% of the time, Romps said, but also accurately represents the apparent temperature for regimes outside those Steadman originally calculated. When he originally published his apparent temperature scale, he considered these regimes too rare to worry about, but high temperatures and humidities are becoming increasingly common because of climate change.

Romps and Lu published the revised heat index equation earlier this year. In the most recent paper, they apply the extended heat index to the top 100 heat waves that occurred between 1984 and 2020. The researchers find mostly minor disagreements with what the NWS reported at the time, but also some extreme situations where the NWS heat index was way off.

One surprise was that seven of the 10 most physiologically stressful heat waves over that time period were in the Midwest -- mostly in Illinois, Iowa and Missouri -- not the Southeast, as meteorologists assumed. The largest discrepancies between the NWS heat index and the extended heat index were seen in a wide swath, from the Great Lakes south to Louisiana.

During the July 1995 heat wave in Chicago, for example, which killed at least 465 people, the maximum heat index reported by the NWS was 135 F, when it actually felt like 154 F. The revised heat index at Midway Airport, 141 F, implies that people in the shade would have experienced blood flow to the skin that was 170% above normal. The heat index reported at the time, 124 F, implied only a 90% increase in skin blood flow. At some places during the heat wave, the extended heat index implies that people would have experienced an increase of 820% above normal skin blood flow.

"I'm no physiologist, but a lot of things happen to the body when it gets really hot," Romps said. "Diverting blood to the skin stresses the system because you're pulling blood that would otherwise be sent to internal organs and sending it to the skin to try to bring up the skin's temperature. The approximate calculation used by the NWS, and widely adopted, inadvertently downplays the health risks of severe heat waves."

Physiologically, the body starts going haywire when the skin temperature rises to equal the body's core temperature, typically taken as 98.6 F. After that, the core temperature begins to increase. The maximum sustainable core temperature is thought to be 107 F -- the threshold for heat death. For the healthiest of individuals, that threshold is reached at a heat index of 200 F.

Luckily, humidity tends to decrease as temperature increases, so Earth is unlikely to reach those conditions in the next few decades. Less extreme, though still deadly, conditions are nevertheless becoming common around the globe.

"A 200 F heat index is an upper bound of what is survivable," Romps said. "But now that we've got this model of human thermoregulation that works out at these conditions, what does it actually mean for the future habitability of the United States and the planet as a whole? There are some frightening things we are looking at."

Read more at Science Daily

Underwater snow gives clues about Europa's icy shell

Below Europa's thick icy crust is a massive, global ocean where the snow floats upwards onto inverted ice peaks and submerged ravines. The bizarre underwater snow is known to occur below ice shelves on Earth, but a new study shows that the same is likely true for Jupiter's moon, where it may play a role in building its ice shell.

The underwater snow is much purer than other kinds of ice, which means Europa's ice shell could be much less salty than previously thought. That's important for mission scientists preparing NASA's Europa Clipper spacecraft, which will use radar to peek beneath the ice shell to see if Europa's ocean could be hospitable to life. The new information will be critical because salt trapped in the ice can affect what and how deep the radar will see into the ice shell, so being able to predict what the ice is made of will help scientists make sense of the data.

The study, published in the August edition of the journal Astrobiology, was led by The University of Texas at Austin, which is also leading the development of Europa Clipper's ice penetrating radar instrument. Knowing what kind of ice Europa's shell is made of will also help decipher the salinity and habitability of its ocean.

"When we're exploring Europa, we're interested in the salinity and composition of the ocean, because that's one of the things that will govern its potential habitability or even the type of life that might live there," said the study's lead author Natalie Wolfenbarger, a graduate student researcher at the University of Texas Institute for Geophysics (UTIG) in the UT Jackson School of Geosciences.

Europa is a rocky world about the size of the Earth's moon that is surrounded by a global ocean and a miles-thick ice shell. Previous studies suggest the temperature, pressure and salinity of Europa's ocean nearest to the ice is similar to what you would find beneath an ice shelf in Antarctica.

Armed with that knowledge, the new study examined the two different ways that water freezes under ice shelves, congelation ice and frazil ice. Congelation ice grows directly from under the ice shelf. Frazil ice forms as ice flakes in supercooled seawater which float upwards through the water, settling on the bottom of the ice shelf.

Both ways make ice that's less salty than seawater, which Wolfenbarger found would be even less salty when scaled up to the size and age of Europa's ice shell. What's more, according to her calculations, frazil ice -- which keeps only a tiny fraction of the salt in seawater -- could be very common on Europa. That means its ice shell could be orders of magnitude purer than previous estimates. This affects everything from its strength, to how heat moves through it, and forces that might drive a kind of ice tectonics.

"This paper is opening up a whole new batch of possibilities for thinking about ocean worlds and how they work," said Steve Vance, a research scientist at NASA's Jet Propulsion Laboratory (JPL) who was not involved in the study. "It sets the stage for how we might prepare for Europa Clipper's analysis of the ice."

According to co-author Donald Blankenship, a senior research scientist at UTIG and principal investigator for Europa Clipper's ice penetrating radar instrument, the research is validation for using the Earth as a model to understand the habitability of Europa.

"We can use Earth to evaluate Europa's habitability, measure the exchange of impurities between the ice and ocean, and figure out where water is in the ice," he said.

Read more at Science Daily

All the better to better eat you with -- dinosaurs evolved different eye socket shapes to allow stronger bites

Large dinosaur predators, such as Tyrannosaurus rex, evolved different shapes of eye sockets to better deal with high bite forces, new research has shown.

While in many animals -- and most dinosaurs -- the eye socket is just a circular hole in the skull housing the eyeball, this is very different in large carnivores.

In a new study, published today in Communications Biology, researchers at the University of Birmingham reveal how the unusual elliptical, or oval eye sockets found in the skulls of these predators, could have evolved to help the skull absorb impact as they pounced on prey.

Dr Stephan Lautenschlager, Senior Lecturer for Palaeobiology at the University of Birmingham and author of the new study, analysed the shape of the eye sockets of ca. 500 different dinosaurs and related species.

"The results show that only some dinosaurs had eye sockets that were elliptical or keyhole-shaped," said Dr Stephan Lautenschlager. "However, all of those were large, carnivorous dinosaurs with skull lengths of 1 m or more."

Using computer simulations and stress analysis, Dr Lautenschlager tested what purpose these unusual eye socket shapes could have.

The results demonstrated that a skull with a circular eye socket was more prone to high stresses during biting. However, if these were replaced with other eye socket shapes stresses were considerably reduced allowing top predators, including Tyrannosaurus rex, to evolve high bite forces without compromising skull stability.

The study also showed that most plant-eating species and juvenile individuals retained a circular eye socket. Only large carnivores adopted other morphologies, such as elliptical, keyhole-shaped or figure-of-eight-shaped eye sockets.

Dr Lautenschlager added: "In these species, just the upper part of the eye socket was actually occupied by the eyeball. This also led to a relative reduction of eye size compared with skull size."

Read more at Science Daily

Nuclear war would cause a global famine and kill billions

More than 5 billion people would die of hunger following a full-scale nuclear war between the U.S. and Russia, according to a global study led by Rutgers climate scientists that estimates post-conflict crop production.

"The data tell us one thing: We must prevent a nuclear war from ever happening," said Alan Robock, a Distinguished Professor of climate science in the Department of Environmental Sciences at Rutgers Universityand co-author of the study. Lili Xia, an assistant research professor in the Department of Environmental Sciences at Rutgers,is lead author of the study published in the journal Nature Food.

Building on past research, Xia, Robock and their colleagues worked to calculate how much Sun-blocking soot would enter the atmosphere from firestorms that would be ignited by the detonation of nuclear weapons. Researchers calculated soot dispersal from six war scenarios -- five smaller India-Pakistan wars and a large U.S.-Russia war -- based on the size of each country's nuclear arsenal.

These data then were entered into the Community Earth System Model, a climate forecasting tool supported by the National Center for Atmospheric Research (NCAR). The NCAR Community Land Model made it possible to estimate productivity of major crops (maize, rice, spring wheat and soybean) on a country-by-country basis. The researchers also examined projected changes to livestock pasture and in global marine fisheries.

Under even the smallest nuclear scenario, a localized war between India and Pakistan, global average caloric production decreased 7 percent within five years of the conflict. In the largest war scenario tested -- a full-scale U.S.-Russia nuclear conflict -- global average caloric production decreased by about 90 percent three to four years after the fighting.

Crop declines would be the most severe in the mid-high latitude nations, including major exporting countries such as Russia and the U.S., which could trigger export restrictions and cause severe disruptions in import-dependent countries in Africa and the Middle East.

These changes would induce a catastrophic disruption of global food markets, the researchers conclude. Even a 7 percent global decline in crop yield would exceed the largest anomaly ever recorded since the beginning of Food and Agricultural Organization observational records in 1961. Under the largest war scenario, more than 75 percent of the planet would be starving within two years.

Researchers considered whether using crops fed to livestock as human food or reducing food waste could offset caloric losses in a war's immediate aftermath, but the savings were minimal under the large injection scenarios.

"Future work will bring even more granularity to the crop models," Xia said.

"For instance, the ozone layer would be destroyed by the heating of the stratosphere, producing more ultraviolet radiation at the surface, and we need to understand that impact on food supplies," she said.

Climate scientists at the University of Colorado, which partnered with Rutgers on the study, are also creating detailed soot models for specific cities, such as Washington, D.C., with inventories of every building to get a more accurate picture of how much smoke would be produced.

Robock said researchers already have more than enough information to know that a nuclear war of any size would obliterate global food systems, killing billions of people in the process.

"If nuclear weapons exist, they can be used, and the world has come close to nuclear war several times," Robock said. "Banning nuclear weapons is the only long-term solution. The five-year-old UN Treaty on the Prohibition of Nuclear Weapons has been ratified by 66 nations, but none of the nine nuclear states. Our work makes clear that it is time for those nine states to listen to science and the rest of the world and sign this treaty."

Read more at Science Daily

Road signs for immune defense cells

Organisms are constantly invaded by pathogens such as viruses. Our immune system swings into action to combat these pathogens immediately. The innate non-specific immune response is triggered first, and the adaptive or acquired immune response follows. In this second defence reaction, specialised cytotoxic T lymphocytes known as killer T cells destroy cells in the body that have been infected and thus prevent damage from spreading. Humans possess a repertoire of some 20 million T cell clones with varying specificity to counter the multitude of infectious agents that exist. But how do the killer T cells know where danger is coming from? How do they recognise that something is wrong inside a cell in which viruses are lurking? They can't just have a quick peek inside.

At this point, antigen processing comes into play. The process can be compared to making a road sign. The molecular barcode is "processed" or assembled in the cell -- in the endoplasmic reticulum, to be exact. Special molecules are used in its making, the MHC class I molecules. They are loaded with information about the virus invader in a molecular machine, the peptide loading complex (PLC). This information consists of peptides, fragments of the protein foreign to the body. These fragments also contain epitopes, the molecular segments that elicit a specific immune response. During the loading process, an MHC I-peptide epitope complex thus forms, and this is the road sign that is then transported to the surface of the cell and presented in a readily accessible form to the killer T cells -- we could almost say that it is handed to them on a silver platter. The chaperones, special accessory proteins that assist the correct folding of proteins with complex structures in cells, also play a significant role.

The chaperones that support antigen processing are calreticulin, ERp57, and tapasin. But how do they work together? And how important are they for antigen processing? An answer has now been supplied by a study carried out by Goethe University Frankfurt and the University of Oxford and published in Nature Communications. "With this study, we have achieved a breakthrough in our understanding of cellular quality control," says Professor Robert Tampé, Director of the Institute of Biochemistry at Goethe University Frankfurt. He explains the logic underlying this quality control process as follows: "The MHC I-peptide epitope complex, the road sign, needs to be exceptionally stable, and for quite a long time, because the adaptive immune response does not start instantly. It needs 3 to 5 days to get going." So, the sign must not collapse after one day; that would be disastrous, as the immune defence cells would then fail to detect cells infected by a virus. This would mean that they would not destroy these cells and the virus would be able to continue its spread unhindered. A similar problem would arise if a cell in the body had mutated into a tumour cell: the threat would remain undetected. It is imperative, therefore, that a quality control system is in place.

As the study shows, the chaperones are central process components: they give the road sign the long-term stability it must have by making a strict selection. By rejecting the short-lived virus fragments in the mass of available material, they ensure that only MHC I molecules loaded with the best and most stable peptide epitopes in complex with MHC I are released from the peptide loading complex. The chaperones have different tasks in this selection process that is so important for the adaptive immune response, Tampé says: "Tapasin acts as a catalyst that accelerates the exchange of suboptimal peptide epitopes for optimal epitopes. Calreticulin and ERp57, in contrast, are deployed universally." This concerted approach ensures that only stable MHC I complexes with optimal peptide epitopes reach the cell surface and perform their role of guiding the killer T cells to the infected or mutated cell.

Read more at Science Daily

Meteorite provides record of asteroids 'spitting out' pebbles

In 2019, NASA's OSIRIS-REx spacecraft sent back images of a geological phenomenon no one had ever seen before: pebbles were flying off the surface of the asteroid Bennu. The asteroid appeared to be shooting off swarms of marble-sized rocks. Scientists had never seen this behavior from an asteroid before, and it's a mystery exactly why it happens. But in a new paper in Nature Astronomy, researchers show the first evidence of this process in a meteorite.

"It's fascinating to see something that was just discovered by a space mission on an asteroid millions of miles away from Earth, and find a record from the same geological process in the museum's meteorite collection," says Philipp Heck, the Robert A. Pritzker Curator of Meteoritics at Chicago's Field Museum and the senior author of the Nature Astronomy study.

Meteorites are pieces of rock that fall to Earth from outer space; they can be made of pieces of moons and planets, but most often, they're broken-off bits of asteroids. The Aguas Zarcas meteorite is named after the Costa Rican town where it fell in 2019; it came to the Field Museum as a donation from Terry and Gail Boudreaux. Heck and his student, Xin Yang, were preparing the meteorite for another study when they noticed something strange.

"We were trying to isolate very tiny minerals from the meteorite by freezing it with liquid nitrogen and thawing it with warm water, to break it up," says Yang, a graduate student at the Field Museum and the University of Chicago and the paper's first author. "That works for most meteorites, but this one was kind of weird -- we found some compact fragments that wouldn't break apart."

Heck says that finding bits of meteorite that won't disintegrate isn't unheard of, but scientists usually just shrug and break out the mortar and pestle. "Xin had a very open mind, he said, 'I'm not going to crush these pebbles to sand, this is interesting,'" says Heck. Instead, the researchers devised a plan to figure out what these pebbles were and why they were so resistant to breaking apart.

"We did CT scans to see how the pebbles compared to the other rocks making up the meteorite," says Heck. "What was striking is that these components were all squished -- normally, they'd be spherical -- and they all had the same orientation. They were all deformed in the same direction, by one process." Something had happened to the pebbles that didn't happen to the rest of the rock around them.

"This was exciting, we were very curious about what it meant," says Yang.

The scientists had a clue, though, from the 2019 OSIRIS-REx findings. From there, they put together a hypothesis, which they supported with physical models. The asteroid underwent a high-speed collision, and the area of impact got deformed. That deformed rock eventually broke apart due to the huge temperature differences the asteroid experiences when it rotates, since the side facing the sun is more than 300° F warmer than the side facing away. "This constant thermal cycling makes the rock brittle, and it breaks apart into gravel," says Heck.

These pebbles are then ejected from the asteroid's surface. "We don't yet know what the process is that ejects the pebbles," says Heck -- they might be dislodged by smaller impacts other space collisions, or they might just get released by the thermal stress the asteroid undergoes. But once the pebbles are disturbed, Heck says, "you don't need much to eject something -- the escape velocity is very low." A recent study of Bennu revealed that its surface is loosely bound and behaves like popcorn in a bucket.

The pebbles then entered a very slow orbit around the asteroid, and eventually, they fell back down to its surface further away where there was no deformation. Then, Heck and Yang say, the asteroid underwent another collision, the loose mixed pebbles on the surface got transformed into a solid rock. "It basically packed everything together, and this loose gravel became a cohesive rock," says Heck. The same impact may have dislodged the new rock, sending it careening into space. Eventually, that chunk fell to Earth as the Aguas Zarcas meteorite, carrying evidence of the pebble mixing.

This could explain the pebbles present in Aguas Zarcas, making the meteorite the first physical evidence of the geological process observed by OSIRIS-REx on Bennu. "It provides a new way of explaining the way that minerals on the surfaces of asteroids get mixed," says Yang.

That's a big deal, Heck says, because for a long time, scientists assumed that the main way that the minerals on the surfaces of asteroids get rearranged is through big crashes, which don't happen very often. "From OSIRIS-REx we know that these particle ejection events are much more frequent than these high-velocity impacts," says Heck, "so they probably play a more important role in determining the makeup of asteroids and meteorites."

Read more at Science Daily

Newly identified fossil insect used 360-degree vision and sticky feet to find and snare its meals

With bulging eyes, an elongated mouth and feet that oozed resin, a fossil insect identified by Oregon State University research is so different from anything alive today that it needed to be placed in its own, extinct family.

George Poinar Jr., professor emeritus in the OSU College of Science, named the insect Palaeotanyrhina exophthalma in a paper published in BioOne Complete. Encased in 100-million-year-old amber from Burma, P. exophthalma is a member of the Hemiptera order -- a "true bug," Poinar said.

"It is a small predator that used its protruding eyes to locate insect prey," said Poinar, an international expert in using plant and animal life forms preserved in amber to learn about the biology and ecology of the distant past.

More than 80,000 species including cicadas, aphids, planthoppers, leafhoppers, bed bugs and shield bugs comprise the order of Hemiptera, an ancient Greek word meaning half-winged. True bugs' size varies widely, from as small as 1 millimeter to as large as 15 centimeters, but they all have a similar arrangement of sucking mouthparts.

P. exophthalma has a body length of just over 5 millimeters. It shares some features with members of the Reduvoidea superfamily, which includes the assassin bug and the kissing bug, but its long labium (lower mouth), its head shape and its forewing veins disqualify it from placement in any modern Reduvoidea family, Poinar said.

Thus he assigned it to a new, extinct family: Palaeotanyrhinidae.

"Its eyes provided a clear, 360-degree view of its habitat so it could see prey that might appear from any side," Poinar said.

It reminded Poinar of the phrase, "Big brother is always watching you," from George Orwell's novel "1984" in which security cameras followed individuals' every movement.

The other strange feature on this fossil is an extended sheath on the final leg segment of the front tarsus, he added.

"That sheath was filled with a resinous substance," Poinar said. "The sticky substance was produced by dermal glands and helped the insect grasp potential prey."

Read more at Science Daily

Sponges 'sneeze' to dispose of waste

Sneezing out mucus may be one of the oldest ways for organisms to get rid of unwanted waste. A group of researchers found that sponges, one of the oldest multicellular organisms in existence, "sneeze" to unclog their internal filter systems that they use to capture nutrients from the water. Additionally, authors find that other animals who live with the sponges use their mucus as food. Their findings are publishing August 10 in the journal Current Biology.

"Our data suggest that sneezing is an adaptation that sponges evolved to keep themselves clean," says Jasper de Goeij, a marine biologist at the University of Amsterdam and the senior author of the paper.

While the field has known about this behavior for years, the authors of this paper show that these sneezes get rid of materials the sponges cannot use. "Let's be clear: sponges don't sneeze like humans do. A sponge sneeze takes about half an hour to complete. But both sponge and human sneezes exist as a waste disposal mechanism," says de Goeij.

Sponges gather food for themselves by filtering out organic matter from the water. They draw in and eject water from different openings, and sometimes the sponges will suck in particles that are too big. "These are sponges; they can't just walk to somewhere else when the water around them gets too dirty for them to handle," says de Goeij. This is when the "sneezing" mechanism comes in handy.

In videos that the authors included in the paper, you can see the water inlets slowly release mucus, and the mucus will accumulate at the surface of the sponge. Occasionally, sponge tissue will contract and push the waste-containing mucus into the surrounding water.

While the mucus may be waste to sponges, the fishes who live around them think otherwise. "We also observed fish and other animals feeding off of the sponge mucus as food," says Niklas Kornder, the first author of the study and a doctoral researcher in de Goeij's research group. "Some organic matter exists in the water surrounding the coral reef, but most of it is not concentrated enough for other animals to eat. Sponges transform this material into eatable mucus," says Kornder.

The paper recorded "sneezing" behavior in two species of sponges, the Caribbean tube sponge Aplysina archeri and another Indo-Pacific species of the genus Chelonaplysilla. "We actually think that most, if not all, sponges sneeze. I've seen mucus accumulate on different sponges while diving and in pictures taken by other scientists for other purposes," says Kornder.

"Our findings highlight opportunities to better understand material cycling in some of the most ancient Metazoans," say the authors in the paper.

There are still many aspects about sponge "sneezes" that remain open questions. "In the videos, you can see that the mucus moves along defined paths on the surface of the sponge before accumulating. I have some hypotheses, but more analysis is needed to find out what is happening," says Kornder.

Read more at Science Daily