Science News

Water exists on sunny parts of the moon, scientists confirm

Mon, 26 Oct 2020 16:00:00 GMT

Past observations have suggested that there’s water on the moon. New telescope observations conclude that those findings hold water.

Spacecraft have seen evidence of water ice in permanently shadowed craters at the lunar poles (SN: 5/9/16), as well as hints of water molecules on the sunlit surface (SN: 9/23/09). But water sightings in sunlit regions have relied on detection of infrared light at a wavelength that could also be emitted by other hydroxyl compounds, which contain hydrogen and oxygen.

Now, the Stratospheric Observatory for Infrared Astronomy, or SOFIA, has detected an infrared signal unique to water near the lunar south pole, researchers report online October 26 in Nature Astronomy. “This is the first unambiguous detection of molecular water on the sunlit moon,” says study coauthor Casey Honniball, a lunar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “This shows that water is not just in the permanently shadowed regions — that there are other places on the moon that we could potentially find it.”

These observations could inform future missions to the moon that will scout out lunar water as a potential resource for human visitors (SN: 12/16/19).

SOFIA, operated by NASA and the German Aerospace Center, is a 2.5-meter telescope that rides aboard a jumbo jet to get clear views of the sky (SN: 2/17/16). During a flight in August 2018, the telescope detected 6-micrometer infrared light emanating from a region near the moon’s southern Clavius crater. This wavelength of light is generated by the vibrations of sunlight-heated water molecules, but not other compounds containing hydroxyl, which consists of an oxygen atom bound to a hydrogen atom.

“I thought it was really brilliant” to confirm the presence of water on the moon with observations at this wavelength, says Jessica Sunshine, a planetary scientist at the University of Maryland in College Park. Sunshine was involved in past observations that spotted hints of water on the moon, but was not involved in the new study.

Based on the brightness of the observed infrared light, Honniball’s team calculated a water concentration of about 100 to 400 parts per million around the Clavius crater. That’s less than half a liter of water per metric ton of lunar soil. This concentration was about what the researchers expected, based on past spacecraft observations.

These water molecules are not frozen in ice, like the water in permanently shadowed regions of the moon. Nor is it liquid, Sunshine says. “There’s no moon puddles.” Instead, the water molecules are thought to be bound inside some other material on the lunar surface.

“The only way for us to be seeing water on the [sunlit] moon is if it is sheltered from this harsh environment,” Honniball says. These water molecules could be encased in glass forged by micrometeorite impacts, or wedged between soil grains that shield the water from blistering solar radiation.

Water could have formed on the moon itself, from hydrogen ions in the continual outward flow of charged particles from the sun reacting with oxygen on the surface (SN: 10/6/14). Or, if the water is stored in impact glass, it could have been delivered to the moon by micrometeorites.

How malaria parasites hide from the human immune system

Mon, 26 Oct 2020 16:00:00 GMT

Malaria parasites survive tough times by not being too clingy.

During Africa’s dry season, when mosquitoes are scarce, malaria parasites have a hard time spreading to new hosts. So the parasites hide out in the human body by keeping the cells they infect from clinging to blood vessels, researchers report October 26 in Nature Medicine. This way, infected cells get removed from circulation and parasite levels in the body remain low, making people less sick and allowing the parasite to persist undetected.

Doctors have long observed that symptoms of malaria, a deadly mosquito-borne infection, tend to wane during the dry season, which runs from January to May. But the reason has been unclear.

Keeping a low profile during dry months is a successful strategy for the parasite, says Martin Rono, a parasitologist at the KEMRI-Wellcome Trust in Kilifi, Kenya, who was not involved in the work. Knowing how malaria parasites persist without causing disease, until mosquitoes return to ferry the organisms from an infected person to the next victim could help efforts to control malaria during the dry season.

Plasmodium falciparum, the parasite responsible for malaria, infects red blood cells as part of a complex life cycle. Once inside a cell, the parasite produces proteins that dock on the cell’s exterior and make it stick to blood vessels so that it won’t be carried to the spleen, where it would otherwise get removed from the body.

Typically, only the early life stages of the parasite circulate in the blood, while older parasites thrive inside red blood cells adhered to blood vessels, says Silvia Portugal, a biologist who led the work while at Heidelberg University Hospital in Germany. “That’s textbook, so it was very surprising” to see that dry-season parasites behaved differently in the lab, she says—the cells weren’t sticking.

Portugal, now at the Max Planck Institute for Infection Biology in Berlin, and her colleagues identified around 600 people in Mali infected with malaria in 2017 and 2018. First, the team ruled out two other ideas to explain the parasite’s seasonality: genetic diversity and immunity. Genetically distinct parasites did not hit at different seasons, nor did the host immune system suppress the parasite’s growth, the team found.

But when the researchers compared which genes were turned on or off in samples taken from asymptomatic people in the dry season and symptomatic people in the wet season, they saw that 1,607 genes had distinct seasonal patterns. In the dry season, 1,131 genes were turned on that were off in wet-season parasites. Another 476 were turned off in dry-season parasites, suggesting that when the wet season ends, P. falciparum may alter its genetics to make red blood cells less sticky. That allows the parasite to replicate and persist without setting off alarm bells that alert the immune system to fight the infection.

Blood cells infected with malaria use certain proteins to adhere to blood vessels almost like Velcro, Portugal says. The loss of stickiness could be because the parasite makes fewer of these proteins, or because the proteins are different in some way.

It’s still unclear, however, which specific genes are involved in the shift. One issue is that the researchers compared parasites from two different life stages, says Abdirahman Abdi, a parasitologist also at the KEMRI-Wellcome Trust. To narrow down which genes may be affecting stickiness, he says, the researchers may need to compare genetic activity in parasites at the same stage.

The longest trail of fossilized human footprints hints at a risky Ice Age trek

Mon, 26 Oct 2020 10:00:00 GMT

On a day during the late Ice Age, a young adult or teen carrying a toddler hustled across a muddy flat where mammoths and giant sloths roamed. Now, over 10,000 years later, fossilized footprints reveal that possibly perilous journey.

The tracks, found in New Mexico’s White Sands National Park, stretch for nearly 1.5 kilometers across the plain and back, making them the longest set ever found, researchers report in the Dec. 1 Quaternary Science Reviews.

“The length of the trackway is really exceptional and give us a prolonged window into the behavior of the individuals,” says evolutionary biologist Kevin Hatala of Chatham University in Pittsburgh, who was not involved in the research. It evokes a personal and intimate connection with our ancestors, as many people today can relate to the feeling of holding a child in their arms, he says.

Scientists stumbled across the find when, in 2018, they spied a continuous stretch of dark spots along what was once the shore of the ancient Lake Otero, now dried up. A little digging revealed fossilized human footprints as well as those from a mammoth and ground sloth.

Of the 427 human footprints discovered, researchers analyzed 90. The size and the depth of the footprints suggest that they had been made by a teen or a young woman, the researchers say. Uneven prints hint that the surface was slippery and that on one leg of the journey, the person at times shifted a heavy load. That load appeared to be a child: Smaller prints from perhaps a 3-year-old appeared next to the larger footprints in several spots.

“It looks like the person was in a hurry, we don’t know why. It was a fast walk and looks like the person was tired… but kept going,” says David Bustos, a biologist at the White Sands National Park.

A set of fossilized human footprints (closeup of one, right) found at White Sands National Park in New Mexico extend some 1.5 kilometers along what was once a lake. The person followed the same route out and back (left) during the late Ice Age.M.R. Bennett et al/Quaternary Science Reviews

That hurry might have been due to the riskiness of the journey. Previously found footprints from the area came from groups of people (SN: 4/25/18). They likely moved in groups to safely hunt animals such as mammoths, sloths and wolves, Bustos says.

In this case, footprints from a mammoth and ground sloth crisscrossed the human prints; in some spots, the human footprints came first while in others, the human stepped on the other animals’ tracks. Based on when those animals went extinct, researchers were able to broadly date the human footprints to the late Ice Age.

While it is unclear if the mammoth sensed the human presence, the giant ground sloth rose onto its hind legs and moved in circles, suggesting that it knew that there was a human nearby, the researchers say. It’s possible that such animals were coming in contact with humans on a regular basis, Hatala says.

Why bat scientists are socially distancing from their subjects

Fri, 23 Oct 2020 12:00:00 GMT

There’s nothing Winifred Frick likes better than crawling through guano-filled caves and coming face-to-face with bats. As chief scientist of Bat Conservation International, she is on a mission to promote understanding of bats and protect imperiled species from extinction.

For months, though, Frick has avoided research that would put her within spitting distance of bats. Her only projects to persist through the pandemic have been conducted from afar, like using acoustic monitors to eavesdrop on the animals’ squeaks and swooshes. In an era of COVID-19, that “hands-off” approach and other precautions are crucial to protect both bats and people, Frick, a biologist at the University of California, Santa Cruz, and over two dozen other scientists argue online September 3 in PLOS Pathogens.

Why the call to action? SARS-CoV-2, the virus that causes COVID-19, likely originated in bats in China (SN: 3/26/20). But neither it nor other coronaviruses belonging to the same genus — Betacoronavirus — have been detected in the more than 40 bat species in North America, although the animals do harbor other types of coronaviruses. Scientists are not worried about catching SARS-CoV-2 from these bats. They’re afraid of giving it to the bats — not an impossibility, the authors argue, given that the United States leads the world in infections, with nearly 8 million as of October 16.

“We can’t tell bats to socially distance,” Frick says. “We want to reduce the chance that there’s any pathogen transfer across animals, full stop.” The goal is to prevent viral “spillover.”

Biologist Winifred Frick advocates for distanced research methods and extra protective gear to safeguard North American bats from the coronavirus.Alan Hicks

Human-to-bat transmission isn’t an unheard-of scenario. People are likely to blame for introducing Pseudogymnoascus destructans, the fungus that causes white nose syndrome, to North American bats. The disease has killed millions of bats throughout the United States and Canada since it was first detected in 2006 (SN: 3/31/16).

It’s unknown if bats are susceptible to SARS-CoV-2 infection, or if the virus would make them sick — bats rarely become ill from the viruses they carry (SN: 2/12/20). But infected bats might spread the virus back to humans, the authors say.

Worse, introducing SARS-CoV-2 to other coronaviruses carried by North American bats could provide the ingredients for creating a new virus (SN: 11/30/17). Either scenario could stoke pre-existing fears about bats spreading disease, presenting a major hurdle for bat conservationists trying to bolster support for the animals.

The International Union for the Conservation of Nature’s bat specialist group, which includes Frick, initially advocated for the hands-off approach in April. Because so little was known in the early days of the pandemic about how SARS-CoV-2 spreads, that group recommended that researchers shut down any projects that involved interacting with bats. In August, the group updated its guidelines to also address spelunking and other activities that might bring humans into bat habitat.

The guidelines still recommend replacing fieldwork with distanced alternatives whenever possible. Picking through guano can identify bat species and reveal the viruses they carry, and cameras positioned outside bat caves and roosts can give a sense of abundance. Scientists can even resurrect evidence of pathogens held in the preserved tissues of bat specimens in museums.

But not all bat research can be socially distanced, and that means taking pandemic precautions, like ensuring field crews aren’t sick with COVID-19 and are wearing personal protective gear. White nose syndrome research already requires disposable Tyvek suits and gloves to reduce spreading the fungus. Now, masks will be a regular part of the ensemble.

For Frick, speaking up for bats has always been a part of being a bat biologist. Besides having a passion for the animals, conservation and human health are inseparable, she says. And bats provide ecosystem services that benefit humans, like pest control that saves North American farmers more than an estimated $3.7 billion per year, according to a study published in 2011 in Science. As human populations expand into shrinking bat habitat, bats and humans increasingly cross paths, making viral spillover events and other harmful interactions more likely. The pandemic has intensified those risks, and for Frick, put the need to speak up “on steroids now.”

The arthritis drug tocilizumab doesn’t appear to help fight COVID-19

Fri, 23 Oct 2020 10:00:00 GMT

An initial crop of clinical trials testing an anti-inflammatory drug against COVID-19 do not look promising.

The best available evidence among these trials “doesn’t show that this drug is beneficial,” says Adarsh Bhimraj, an infectious diseases physician at the Cleveland Clinic, who was not involved in the research.

The drug, tocilizumab, is a treatment for the painful joint swelling that occurs in rheumatoid arthritis and is also used to manage a dangerous side effect of the cancer treatment CAR-T cell therapy (SN: 6/27/18). So clinical trials have been assessing whether tocilizumab might help COVID-19 patients by taming excessive inflammation as it does for these other two conditions.

The drug works by blocking the activity of a protein called interleukin 6, which contributes to the immune system’s inflammatory response. High levels of this protein, known as a cytokine, are a harbinger of severe disease in COVID-19 patients, studies have found.

Of the four clinical trials that have just reported peer-reviewed results on tocilizumab for COVID-19, only one meets the “gold standard” for evaluating a drug. Such randomized, double-blinded controlled trials randomly assign patients to receive a drug or a placebo, and don’t reveal to participants or doctors who is getting which.

In the trial with this design, tocilizumab did not reduce the risk of intubation or death as of four weeks compared with the placebo, researchers reported online in the New England Journal of Medicine on October 21. The study included 243 participants hospitalized with COVID-19 at seven Boston hospitals. Two-thirds received the drug, while the remainder received the placebo; participants also got other available drugs for COVID-19, such as remdesivir (SN: 5/13/20).

Two other trials randomly assigned which participants received tocilizumab but did not use a placebo, and it was clear whether patients were receiving the drug or not. This knowledge can bias the interpretation of some measures of how a patient is faring.

One of these two studies had mixed results. Tocilizumab may have reduced the likelihood of patients needing ventilation or dying as of two weeks compared with those who didn’t receive the drug. But there was no difference in mortality between the two groups at four weeks, researchers reported online October 20 in JAMA Internal Medicine. In the trial of 131 patients with COVID-19 pneumonia at nine hospitals in France, about half got tocilizumab along with regular care (such as antiviral drugs), while the remainder received just regular care.

The other study of 126 patients in 24 hospitals in Italy found that the drug didn’t appear to stop the disease from getting worse compared with standard care, researchers reported in JAMA Internal Medicine, also on October 20. About half the patients with COVID-19 pneumonia got the drug. The other half received standard care but could get tocilizumab if their condition worsened.

“The data from randomized controlled trials published to date do not support routine use of tocilizumab in patients hospitalized with COVID-19,” says Carolyn Calfee, a pulmonary and critical care specialist at the University of California, San Francisco School of Medicine, who was not involved in the trials.

There are some blanks still to be filled in, though. The trials didn’t evaluate patients with the most severe forms of COVID-19, namely those with acute respiratory distress syndrome on a ventilator, Calfee says. It’s also unclear whether categorizing patients by how much their interleukin 6 level is elevated might help identify patients who could benefit from the drug, she says.

The only study that found tocilizumab helpful had a weaker design. It was an observational study, so not randomized. The participants who received the drug had different characteristics from those who didn’t, which makes it difficult to determine whether the results are due to the drug or other factors. By 30 days, the risk of mortality was lower for hospitalized patients who took the drug in the first two days upon admission than for patients who didn’t, researchers report online October 20 in JAMA Internal Medicine.

Bhimraj says results from the remaining “gold standard” clinical trials still under way will be needed to better understand whether tocilizumab has a use in treating COVID-19. One trial offered preliminary results in a news release and reported that participants were less likely to need intubation or die with the drug (SN: 9/22/20).

Bat-winged dinosaurs were clumsy fliers

Thu, 22 Oct 2020 16:02:37 GMT

Only two dinosaur species are known to have had wings made out of stretched skin, like bats. But unlike bats, these dinos were capable of only limited gliding between trees, a new anatomical analysis suggests. That bat-winged gliding turned out to be a dead end along the path to the evolution of flight, researchers say.

“They are a failed experiment,” says Alexander Dececchi, a paleontologist at Mount Marty University in Sioux Falls, S.D.

Fliers with feathered wings, rather than membranous wings, begin to appear in the fossil record just a few million years after the bat-winged dinosaurs. Those feathered fliers may have outcompeted the gliders in their evolutionary niche, Dececchi and colleagues suggest October 22 in iScience.

Yi qi and Ambopteryx longibrachium were crow-sized dinosaurs that lived about 160 million years ago (SN: 4/29/15). They were distant cousins, both belonging to a bizarre group of dinosaurs known as scansoriopterygids. Unlike other scansoriopterygids, however, these two species sported large wings with membranes, thin skin stretched between elongated arm bones.

Scansoriopterygids were a branch of theropod dinosaurs, the same group that includes giants like Tyrannosaurus rex as well as the ancestors of birds. So the recent discoveries of two different bat-winged theropod dinosaurs shook up long-standing ideas about the evolution of flight in birds. Scientists had thought that path, while a bit circuitous, centered around variations of just one basic, birdlike body plan.

But whether Yi and Ambopteryx were actually adept at flying, such as being able to launch from the ground or flap their wings, wasn’t clear. To assess the dinos’ flight capability, Dececchi and colleagues used laser-stimulated fluorescence imaging, which can pick up details of soft tissues such as membranes or cartilage in fossils, to reanalyze the anatomy of Yi and Ambopteryx. The team made new estimations of the reptiles’ weight, wing shape and wingspan, and then simulated how those features might translate into flapping, gliding or launching.

The new analyses confirm that these two dinosaurs had vastly different wing structures from the feathered-wing fliers — proving that these two flight strategies evolved independently of one another. Yi and Ambopteryx, for example, had elongated forelimb bones between their membranous wings, as well as a special wrist bone to help support the membrane. The skeletons of the wings of birds, on the other hand, consist of elongated metacarpals, similar to finger bones.

This evolutionary branching out was ultimately a failure, Dececchi says. Yi and Ambopteryx were capable only of gliding short distances from tree to tree, the team found. Their body mass-to-wing ratio was a bit too high for them to stay aloft to glide longer distances.

As for active flight, the dinosaurs lacked other attributes possessed by powerful fliers, whether feather-winged like birds or membrane-winged like pterosaurs and bats. For example, the orientation of the dinosaurs’ wings suggests that they weren’t designed for rotational flapping. And the dinos’ breastbones show no evidence of places where key flight muscles attach in modern birds (SN: 3/13/18).

Just a few million years after Yi and Ambopteryx, about 150 million years ago, the ancient bird Archaeopteryx appears in the fossil record. Although Archaeopteryx wasn’t a particularly great flier either, Dececchi says, it was a stronger glider and possibly could flap its wings a bit. Later variations on its body theme continued to improve dinosaur’s flight ability, he says.

That the bat-winged dinosaurs weren’t great fliers isn’t a surprise, says paleontologist Jingmai O’Connor of the Chinese Academy of Sciences in Beijing, who with her colleagues described Ambopteryx in a 2019 study in Nature. O’Connor notes that no bat-winged dinosaurs appear in the fossil record after the Jurassic Period, so it already seemed likely that they weren’t a successful group of dinosaurs. Still, she says, it’s important to do this kind of careful, quantitative analysis to assess flight ability — although “the fossil record of this group is really bad.” With so few fossils, many poorly preserved, any such calculations are going to be based on “very poor data.”

O’Connor says that what the animals do highlight is “the experimentation with different modes of flight,” she adds. Birds, it’s clear, weren’t the only flying dinosaurs — and these fossils reveal that flight itself, whether gliding or powered, evolved multiple times among them.

Homo erectus, not humans, may have invented the barbed bone point

Thu, 22 Oct 2020 11:52:44 GMT

A type of bone tool generally thought to have been invented by Stone Age humans got its start among hominids that lived hundreds of thousands of years before Homo sapiens evolved, a new study concludes.

A set of 52 previously excavated but little-studied animal bones from East Africa’s Olduvai Gorge includes the world’s oldest known barbed bone point, an implement probably crafted by now-extinct Homo erectus at least 800,000 years ago, researchers say. Made from a piece of a large animal’s rib, the artifact features three curved barbs and a carved tip, the team reports in the November Journal of Human Evolution.

Among the Olduvai bones, biological anthropologist Michael Pante of Colorado State University in Fort Collins and colleagues identified five other tools from more than 800,000 years ago as probable choppers, hammering tools or hammering platforms.

The previous oldest barbed bone points were from a central African site and dated to around 90,000 years ago (SN: 4/29/95), and were assumed to reflect a toolmaking ingenuity exclusive to Homo sapiens. Those implements include carved rings around the base of the tools where wooden shafts were presumably attached. Barbed bone points found at H. sapiens sites were likely used to catch fish and perhaps to hunt large land prey.

The Olduvai Gorge barbed bone point, which had not been completed, shows no signs of having been attached to a handle or shaft. Ways in which H. erectus used the implement are unclear, Pante and his colleagues say.

This find and four of the other bone implements date to at least 800,000 years ago, based on their original positions below Olduvai sediment that records a known reversal of Earth’s magnetic field about 781,000 years ago. Another bone artifact dates to roughly 1.7 million years ago, the researchers say.

“The Olduvai point implicates H. erectus as the inventor of barbed bone point technology,” Pante says, because stone tools previously excavated in the same Olduvai Gorge sediment resemble those that have been found at other African sites with H. erectus fossils.

The bone tools described in the new study come from a collection of animal bones excavated in the late 1960s and early 1970s by Mary Leakey before being stored among thousands of fossils and artifacts at an on-site Olduvai facility. Pante discovered the set of 52 bones in 2007 while doing research at Olduvai Gorge.

Still, archaeologist Christian Tryon of the University of Connecticut in Storrs, who did not participate in the new study, questions whether the Olduvai bone specimen can be definitively classed as a barbed bone point because it wasn’t finished. But Pante’s report shows that Olduvai hominids, whether they were H. erectus or some other prehuman population, carefully selected bones as well as stones for toolmaking, Tryon says. “They were expert craftsmen or women.”

New York University archaeologist Justin Pargeter agrees. Although it’s unclear whether the Olduvai artifact was a pointed bone tool comparable to those later made by H. sapiens, he says, the existence of any bone toolmaking 800,000 years ago shows that this practice is far older than typically assumed.

Along with bone toolmaking, a series of critical behavioral advances in hominids occurred before the emergence of H. sapiens around 300,000 years ago. These developments include the invention of stone tools (SN: 6/3/19), controlled fire use (SN: 4/2/12) and the ability to survive in new environments (SN: 11/29/18). Exploiting bone to make tools such as barbed points would have aided ancient Homo groups migrating through unfamiliar regions where locations of stone sources were unknown, Pante suspects.

Jewelry making, cave painting and other symbolic acts may represent “modern human behaviors” that eluded earlier hominids such as H. erectus, Pante says. But some researchers suspect that now-extinct Homo species also created symbolic items (SN: 12/3/14).

How environmental changes may have helped make ancient humans more adaptable

Wed, 21 Oct 2020 19:42:43 GMT

An unforgiving environmental twist deserves at least some credit for the behavioral flexibility that has characterized the human species since our African origins around 300,000 years ago, a new study suggests.

For hundreds of thousands of years in parts of East Africa, food and water supplies remained fairly stable. But new evidence shows that starting about 400,000 years ago, hominids and other ancient animals in the region faced a harsh environmental reckoning, says a team led by paleoanthropologist Rick Potts of the Smithsonian Institution in Washington, D.C.

The climate began to fluctuate dramatically. Faults caused by volcanic eruptions fractured the landscape and reduced the size of lakes. Large animals died out and were replaced by smaller creatures with more diverse diets. These changes heralded a series of booms and busts in the resources hominids needed to survive, Potts and his colleagues report October 21 in Science Advances.

Around that time, hominids at a site called Olorgesailie in what’s now Kenya transformed their culture. That shift, between around 500,000 and 320,000 years ago, was probably influenced by increasingly unpredictable periods of water and food scarcity, the scientists contend.

Stone hand axes and other cutting tools made of local stone had dominated African toolkits for 700,000 years before that transition occurred. After that, Middle Stone Age tools, such as spearpoints made from rock imported from distant sources, gained popularity, Potts’ team has previously found (SN: 3/15/18). Middle Stone Age tools were smaller and more carefully crafted implements. Widely scattered hominid groups began to trade with one another to obtain suitable toolmaking rock and other resources.

Potts has long argued that Olorgesailie hominids evolved genetically and behaviorally to handle frequent climate shifts, a process dubbed variability selection (SN: 7/12/97). But the new study indicates that ancient humans adapted to a number of environmental forces, not just climate fluctuations, he says.

“A cascade of ancient ecological changes led to alternating periods of resource abundance and scarcity, likely helping to make us the most adaptable [hominid] species that ever existed,” Potts says.

Erosion at Olorgesailie has destroyed sediment layers dating to the Middle Stone Age transition. So the researchers hired a Kenyan company to drill as deeply as possible in the Koora basin, located about 24 kilometers south of Olorgesailie. Dating of the 139-meter-long extracted core found that the sediments spanned much of the last 1 million years, making it the best environmental record of that time period for anywhere in Africa, Potts says.

A segment of an East African sediment core (bottom) includes signatures of volcanic blasts, dry and rainy seasons, and changes in land cover (all shown in the top close-ups).Human Origins Program/Smithsonian, core image courtesy of LacCore/Univ. of Minnesota

Chemical and microscopic studies of the core revealed signs of volcanic eruptions having created faults that fragmented the Olorgesailie landscape starting roughly 400,000 years ago. Small ponds and lakes then replaced larger lake basins at a time when rainfall became inconsistent. Intermittent, increasingly frequent dry periods resulted in severe water shortages.

Vegetation changes followed. Shifts back and forth from grassy plains to forests denied large animals, such as elephants, regular access to former grazing areas. Faults in the landscape also reduced the size of any available grazing areas. As Potts’ team has previously found, smaller animals with diverse diets, including antelopes and pigs, became prominent at Olorgesailie during the Middle Stone Age. Stone tools at that time may have been tailored for hunting and processing smaller prey, the researchers say.

Booms and busts in resource availability during the Middle Stone Age each generally lasted for a few thousand years, based on evidence from the Koora sediment core, Potts says. That time resolution is a big improvement over previous studies that used global climate data to reconstruct ancient African environmental changes that occurred over tens of thousands of years, says archaeologist and paleoanthropologist Manuel Will of the University of Tübingen in Germany, who did not participate in the new investigation.

Pott and colleagues’ findings “provide the best evidence yet for a link between environmental changes in East Africa and the spread of Middle Stone Age technology and increased mobility across the landscape,” says paleoanthropologist Chris Stringer of the Natural History Museum in London. Although it’s still unclear where in Africa — as well as when and by whom — Middle Stone Age tools were invented, early humans would have found such implements invaluable for adapting to environmental disruptions, Stringer says.

Olorgesailie’s Middle Stone Age boom-and-bust scenario may not apply to other parts of Africa where spearpoints and related implements didn’t appear until later, cautions archaeologist Lyn Wadley of the University of the Witwatersrand in Johannesburg. In those settings, Middle Stone Age tools may have proven useful even for groups that enjoyed relatively stable water and food sources.

NASA’s OSIRIS-REx survived its risky mission to grab a piece of an asteroid

Wed, 21 Oct 2020 15:26:21 GMT

NASA’s OSIRIS-REx spacecraft is a cosmic rock collector. Cheers erupted from mission control at 6:12 p.m. EDT on October 20 as scientists on Earth got word that the spacecraft had gently nudged a near-Earth asteroid called Bennu, and grabbed some of its rocks to return to Earth.

“The spacecraft did everything it was supposed to do,” said mission principal investigator Dante Lauretta of the University of Arizona in Tucson on a NASA TV webcast. “I can’t believe we actually pulled this off.”

OSIRIS-REx arrived at Bennu in December 2018, and spent almost two years making detailed maps of the 500-meter-wide asteroid’s surface features and composition (SN: 10/8/20). Observations from Earth suggested Bennu should be smooth and sandy, but when OSIRIS-REx arrived, it found a treacherous, rocky landscape.

The team selected a relatively smooth patch in a crater named Nightingale. The spot was not without hazards, though — the team was so worried about a particularly large rock nearby that they named it “Mount Doom” (SN: 12/12/19).

Luckily, the spacecraft did not need to fully land in the crater to complete its mission. As it hovered just above the surface, OSIRIS-REx reached out a robotic arm with an instrument called TAGSAM at the end, for Touch-And-Go Sample Acquisition Mechanism. The instrument tapped the asteroid lightly for several seconds, and released a burst of nitrogen gas to disturb the surface dust and pebbles. Once those small rocks were lofted, some hopefully were blown into the sample collector.

Because signals from Earth take 18½ minutes to reach Bennu, the spacecraft performed the sampling sequence autonomously. When the mission team got the signal that the spacecraft had finished its job and retreated to a safe distance from Bennu, team members pumped their arms in the air, cheered and sent each other socially distant high-fives and hugs.

OSIRIS-REx is not the first spacecraft to grab samples from an asteroid. That distinction goes to Japan’s Hayabusa mission, which brought back grains of asteroid Itokawa in 2010 (SN: 6/14/10). An encore to that mission, Hayabusa2, collected samples of asteroid Ryugu last year, and is on track to land in Australia in December (SN: 2/22/19).

But OSIRIS-REx attempted to collect much more material than Hayabusa2 did. Hayabusa2 hoped to collect 100 milligrams; OSIRIS-REx is aiming for a minimum of 60 grams, or a little more than two ounces.

Hayabusa2’s scientists have no way to know how much material it actually collected until the spacecraft returns to Earth. But OSIRIS-REx’s team plans to find out using the spacecraft itself. On October 24, the spacecraft will extend its arm and spin its whole body. The difference in the way it spins before and after the sample collection will reveal the mass of the sample.

OSIRIS-REx will return to Earth in 2023, where scientists will analyze the rocks in hopes of unlocking details of the history of the solar system and the origins of water and life on Earth (SN: 1/15/19).

The diabolical ironclad beetle can survive getting run over by a car. Here’s how

Wed, 21 Oct 2020 15:00:00 GMT

The diabolical ironclad beetle is like a tiny tank on six legs.

This insect’s rugged exoskeleton is so tough that the beetle can survive getting run over by cars, and many would-be predators don’t stand a chance of cracking one open. Phloeodes diabolicus is basically nature’s jawbreaker.

Analyses of microscope images, 3-D printed models and computer simulations of the beetle’s armor have now revealed the secrets to its strength. Tightly interlocked and impact-absorbing structures that connect pieces of the beetle’s exoskeleton help it survive enormous crushing forces, researchers report in the Oct. 22 Nature. Those features could inspire new, sturdier designs for things such as body armor, buildings, bridges and vehicles.

The diabolical ironclad beetle, which dwells in desert regions of western North America, has a distinctly hard-to-squish shape. “Unlike a stink beetle, or a Namibian beetle, which is more rounded … it’s low to the ground [and] it’s flat on top,” says David Kisailus, a materials scientist at the University of California, Irvine. In compression experiments, Kisailus and colleagues found that the beetle could withstand around 39,000 times its own body weight. That would be like a person shouldering a stack of about 40 M1 Abrams battle tanks.

Within the diabolical ironclad beetle’s own tanklike physique, two key microscopic features help it withstand crushing forces. The first is a series of connections between the top and bottom halves of the exoskeleton. “You can imagine the beetle’s exoskeleton almost like two halves of a clamshell sitting on top of each other,” Kisailus says. Ridges along the outer edges of the top and bottom latch together.

This slice of a diabolical ironclad beetle’s back shows the jigsaw-shaped links that connect the left and right sides of its exoskeleton. These protrusions are tightly interlocked and highly damage-resistant, helping give the beetle its incredible durability.David Kisailus

But those ridged connections have different shapes across the beetle’s body. Near the front of the beetle, around its vital organs, the ridges are highly interconnected — almost like zipper teeth. Those connections are stiff and resist bending under pressure.

The connective ridges near the back of the beetle, on the other hand, are not as intricately interlocked, allowing the top and bottom halves of the exoskeleton to slide past each other slightly. That flexibility helps the beetle absorb compression in a region of its body that is safer to squish.

The second key feature is a rigid joint, or suture, that runs the length of the beetle’s back and connects its left and right sides. A series of protrusions, called blades, fit together like jigsaw puzzle pieces to join the two sides. These blades contain layers of tissue glued together by proteins, and are highly damage-resistant. When the beetle is squashed, tiny cracks form in the protein glue between the layers of each blade. Those small, healable fractures allow the blades to absorb impacts without completely snapping, explains Jesus Rivera, an engineer at UC Irvine.

This toughness makes the diabolical ironclad beetle pretty predator-proof. An animal might be able to make a meal out of the beetle by swallowing it whole, Kisailus says. “But the way it’s built, in terms of other predation — let’s say like a bird that’s pecking at it, or a lizard that’s trying to chew on it — the exoskeleton would be really hard” to crack.

That hard exterior is also a nuisance for insect collectors. The diabolical ironclad beetle is notorious among entomologists for being so fantastically durable that it bends the steel pins usually used to mount insects for display, says entomologist Michael Caterino of Clemson University in South Carolina. But “the basic biology of this thing is not particularly well-known,” he says. “I found it fascinating” to learn what makes the beetle so indestructible.

The possibility of using beetle-inspired designs for sturdier airplanes and other structures is intriguing, Caterino adds. And with the splendid variety of insects all over the world, who knows what other critters might someday inspire clever engineering designs.

Naked mole-rats invade neighboring colonies and steal babies

Tue, 20 Oct 2020 16:00:00 GMT

Naked mole-rats — with their subterranean societies made up of a single breeding pair and an army of workers — seem like mammals trying their hardest to live like insects. Nearly 300 of the bald, bucktoothed, nearly blind rodents can scoot along a colony’s labyrinth of tunnels.

New research suggests there’s brute power in those numbers: Like ants or termites, the mole-rats go to battle with rival colonies to conquer their lands.

Wild naked mole-rats (Heterocephalus glaber) will invade nearby colonies to expand their territory, sometimes abducting pups to incorporate them into their own ranks, researchers report September 28 in the Journal of Zoology. This behavior may put smaller, less cohesive colonies at a disadvantage, potentially supporting the evolution of bigger colonies.

Researchers stumbled across this phenomenon by accident while monitoring naked mole-rat colonies in Kenya’s Meru National Park. The team was studying the social structure of this extreme form of group living among mammals (SN: 6/20/06).

Over more than a decade, the team trapped and marked thousands of mole-rats from dozens of colonies by either implanting small radio-frequency transponder chips under their skin, or clipping their toes. One day in 1994, while marking mole-rats in a new colony, researchers were surprised to find in its tunnels mole-rats from a neighboring colony that had already been marked. The queen in the new colony had wounds on her face from the ravages of battle. It looked like a war was playing out down in the soil.

“Naked mole-rats are better known for their cooperation within colonies than competition between colonies,” notes Stan Braude, a biologist at Washington University in St. Louis. But over the course of the long-term study, Braude and his colleagues found that 26 colonies expanded their tunnels by digging into burrow systems occupied by neighboring colonies. In half of these cases, the invaded colony fled to a different arm of their tunnel system as the invaders expanded their territory. In the other half of cases, the invaded colony was entirely displaced, and the original mole-rats were never encountered there again. In four incursions, researchers caught invading mole-rats in the act, and in three of those, the bigger colony was doing the invading.

Genetic analysis, which was not available during the original research, later confirmed that during the 1994 invasion, the aggressors didn’t just evict the vanquished. They also pup-napped at least two youngsters. The pups grew up to become workers within their captors’ society.

This lust for conquest had been seen before in the species, but only in captive colonies. Confirmation that these conflicts happen naturally in the wild means that they may have some influence on the evolution of the mole-rats’ crowded social lives, Braude says. The total eviction of smaller colonies by larger ones presents a previously unconsidered factor that makes it “important for this species to live in as large a group as possible.”

Nothing about these “crazy beasts” surprises evolutionary biologist Chris Faulkes anymore. “The burrow is a massively valuable resource because it is so costly — in terms of energy — to excavate and build,” says Faulkes, of Queen Mary University of London. It makes sense that mole-rats would not only defend it, but try to pilfer this resource from others.

Since group size is so important to naked mole-rats, Faulkes says it’s interesting that workers from the different colonies don’t join together after an invasion. Only pups are added to the invading colony.

“The numbers of these kidnapped pups is really rather small, and these incidences of kidnapping may not be that frequent,” he says. “Given that, I’m not sure how much that really contributes to building large colony numbers.”

The researchers argue that since there’s such a narrow window of time after birth when a mole-rat can be stolen, the fact that these pup-nappings were documented at all may mean the behavior is fairly common.

Other forces may also be at play in facilitating the rise of large, tight-knit mole-rat colonies, like the spotty distribution of food resources in their harsh, dry habitat.

“Staying safe and finding food are absolutely important,” agrees Braude. Invasions might even abet that, contributing to the success of a mole-rat society. For instance, inhabiting a larger tunnel system may mean more access to the nutritious tubers the mole-rats find and feed upon underground.

Warfare isn’t the only strategy naked mole-rats have to boost their colony’s geographic and genetic influence. Some naked mole-rats are specially equipped with abundant fat reserves that allow them to journey long distances aboveground. These “dispersal morph” individuals interbreed with other colonies’ members and can potentially establish brand new colonies.

Even the deepest, coldest parts of the ocean are getting warmer

Tue, 20 Oct 2020 12:00:00 GMT

Things are heating up at the seafloor.

Thermometers moored at the bottom of the Atlantic Ocean recorded an average temperature increase of about 0.02 degrees Celsius over the last decade, researchers report in the Sept. 28 Geophysical Research Letters. That warming may be a consequence of human-driven climate change, which has boosted ocean temperatures near the surface (SN: 9/25/19), but it’s unclear since so little is known about the deepest, darkest parts of the ocean.

“The deep ocean, below about 2,000 meters, is not very well observed,” says Chris Meinen, an oceanographer at the U.S. National Oceanic and Atmospheric Administration in Miami. The deep sea is so hard to reach that the temperature at any given research site is typically taken only once per decade. But Meinen’s team measured temperatures hourly from 2009 to 2019 using seafloor sensors at four spots in the Argentine Basin, off the coast of Uruguay.

Temperature records for the two deepest spots revealed a clear trend of warming over that decade. Waters 4,540 meters below the surface warmed from an average 0.209° C to 0.234° C, while waters 4,757 meters down went from about 0.232°C to 0.248°C. This warming is much weaker than in the upper ocean, Meinen says, but he also notes that since warm water rises, it would take a lot of heat to generate even this little bit of warming so deep.

It’s too soon to judge whether human activity or natural variation is the cause, Meinen says. Continuing to monitor these sites and comparing the records with data from devices in other ocean basins may help to clarify matters.

Fire ants build little syphons out of sand to feed without drowning

Tue, 20 Oct 2020 10:00:00 GMT

The threat of death is no obstacle for some hungry fire ants. To escape drowning while feeding on sugary water, black imported fire ants built syphons out of sand that moved the water to a safer spot.

A range of animals, including birds, dolphins, primates and even ants, use objects as tools (SN: 12/30/19; SN: 6/25/20; SN: 6/24/19). Ants often employ debris or sand grains to carry food. But this is the first time that the insects have been observed adjusting their tool use to build relatively complex structures in response to a problem, researchers report October 7 in Functional Ecology.

In the wild, black imported fire ants (Solenopsis richteri) typically eat honeydew produced by aphids. In the lab, entomologist Jian Chen of the U.S. Department of Agriculture’s Agricultural Research Service in Stoneville, Miss., and colleagues provided the ants with containers of sugary water. The insects have a hard, water-repellent outer covering called a cuticle, and can typically float on a liquid — and sure enough, the insects floated and fed without a problem.

The researchers then reduced the water’s surface tension with a surfactant to make it more difficult for the ants to float. While some ants drowned, most stopped entering the containers and instead used grains of sand placed nearby to build structures leading from the inside of a container to outside of it. Those structures acted like syphons. Within five minutes of building one, nearly half of the water was drawn out through the sand pathway, allowing the ants to feed safely.

“The fact that ants are building little syphons is new and interesting,” says Valerie Banschbach of Gustavus Adolphus College in Saint Peter, Minn., who was not involved in the study. The insects’ “flexibility to act in a creative way responding to a situation suggests that they have higher cognitive abilities than what is traditionally believed.”

In this time-lapse video, watch how most black imported fire ants avoid drowning by using grains of sand to build relatively sophisticated structures around containers of sugar water. In experiments, it took the ants more than 90 minutes to shift the sand to the containers and do the construction work. Those structures act as syphons to draw the water out of the containers and to a safer place for the ants to feed.

How the insects were able to sense the change in the water’s surface tension is unknown. Some ants that drown initially could be releasing chemical messengers, Chen says, or maybe the ants taste a difference in the water, or a combination of both.

Black imported fire ants are native to South America but have made their way to parts of North America where they are regarded as invasive. The insects can damage crops such as corn, soybeans and okra, and can also sting humans.

A major goal of the project, Chen says, is to develop new pest control measures by better understanding how the ants may behave in their natural habitat. Different types of surfactants are often added to pesticides to help them spread better, the researchers say, so ants could potentially be exposed to similar conditions in the wild as they were in the lab.

For now, Chen is content to marvel at the industrious insects. “Ants are so amazing,” he says. “We have just scratched the surface of the ant world.”

A rope bridge restored a highway through the trees for endangered gibbons

Mon, 19 Oct 2020 16:00:00 GMT

With acrobatic leaps, Hainan gibbons can cross a great gully carved by a 2014 landslide in the forest on China’s Hainan Island. But when a palm frond caught by the vaulting apes to steady their landing started to sag, researchers rushed to provide a safer route across.

Though slow to adopt it, the gibbons increasingly traveled a bridge made of two ropes that was installed across the 15-meter gap, researchers report October 15 in Scientific Reports. The finding suggests that such tethers could also help connect once-intact forests that have been fragmented by human activities and aid conservation efforts of these and other canopy dwellers.

“Fragmentation is becoming an increasing problem,” says Tremaine Gregory, a conservation biologist at the Smithsonian’s National Zoo and Conservation Biology Institute in Washington, D.C., who wasn’t involved in the study. “It’s probably going to be, along with climate change, one of the biggest challenges for biodiversity in decades.”

The landslide damaged an arboreal highway, a preferred route through the trees that the apes use to traverse the rainforest. Hainan gibbons (Nomascus hainanus) are almost strictly arboreal, and forest fragmentation can divide the already critically endangered primates (SN: 8/6/15) into smaller breeding populations, says Bosco Chan, a conservation biologist at the Kadoorie Farm and Botanic Garden in Hong Kong. That can lead to inbreeding or local groups dying out.

Only about 30 individuals remain of this species, all living in a nature reserve on Hainan Island. For the group of nine gibbons studied, the researchers didn’t want the animals to get hurt crossing the gap.

Enter the rope bridge. It took months for the gibbons to catch on, but about 176 days after the bridge’s installation, camera traps captured the gibbons taking to the ropes. “I was very excited when [the gibbons] first started using it,” Chan says.

To cross a gully created by a landslide, some Hainan gibbons dangle and swing from a rope bridge installed by researchers, while others walk across, sometimes using the upper rope as a handrail.Kadoorie Farm and Botanic Garden

Eventually, the scientists observed the gibbons crossing the bridge about as frequently as the animals had traveled that stretch of forest before the landslide. Females and juveniles preferentially used the bridge, while an adult male never used it, and nearly grown juveniles rarely did.

Though the scientists expected the animals would swing along under the bridge using their arms, Chan says, many preferred to walk as though on a tightrope, using one rope as a handrail, or to climb along the ropes using all their limbs. Occasionally, gibbons scampered across without holding on with their upper limbs. For now, the bridge provides a temporary solution while transplants of native trees grow and other trees regenerate.

Such artificial bridges provide a sensible and innovative approach to help gibbons get around safely, says Susan Cheyne, a primatologist based in Oxford, England, and vice chair of the International Union for Conservation of Nature’s Section on Small Apes, who advised the Hainan project. “We want them to stay up in the canopy.” On the ground, gibbons may get hit by cars, get into fights with dogs or be exposed to parasites that the animals wouldn’t typically encounter.

What’s more, the Hainan gibbons’ adoption of the bridge suggests that it’s a “tool that other primate conservation groups could potentially use,” Cheyne says, as these gibbons are a “relatively fickle species. They are not overly keen on using new things,” she says.

Beyond primates, other animals may use such crossings too. The team also saw two squirrels and another rodent use the bridge. Depending on where canopy bridges are located, marsupials or rodents could benefit, though observing such creatures to know for sure could be a challenge if they are nocturnal.

We still don’t know what COVID-19 immunity means or how long it lasts

Mon, 19 Oct 2020 12:00:00 GMT

Even as U.S. President Donald Trump claims his bout with COVID-19 has granted him immunity, reports of people getting the disease a second time are emerging. While reinfection still appears to be rare, it remains unclear to what extent immunity can truly protect a person.

Immunity is also in the news because a debate is simmering among scientists over herd immunity, the point at which enough people are immune to a pathogen to slow its spread (SN: 3/24/20). While herd immunity might put the end of the pandemic in sight, experts estimate that around 40 to 60 percent of a population would need to be infected to reach it.

One group of researchers is pushing for governments to reach herd immunity without a vaccine, by allowing COVID-19 to spread among those at low risk while protecting vulnerable populations. This approach, however, puts the entire population at risk of significant illness and death, another group argues in a letter published October 14 in the Lancet.

Because SARS-CoV-2 is a new virus, scientists can’t say how long a person will be protected after they’ve recovered from an infection. If immunity wanes quickly, that sets the stage for recurrent outbreaks unless there’s a vaccine, the authors say.

Here’s what we know so far about our long-term defenses against the coronavirus:

What does “immunity” really mean?

To scientists, immunity means a resistance to a disease gained through the immune system’s exposure to it, either by infection or through vaccination. But immunity doesn’t always mean complete protection from the virus.

How does the body build immunity?

The immune system has two ways to provide lasting protection: T cells that remember the pathogen and trigger a rapid response, and B cells that produce antibodies — proteins the body makes to fight off a specific pathogen.

Ideally, long after a person has recovered from an infection, these antibodies stick around in their blood. Then if the person is exposed to the same pathogen again in the future, those antibodies recognize the threat and work to prevent another infection from taking hold.

So-called “memory T cells” also stick around. Ideally, they live up to their name and recognize a previously encountered pathogen and either help coordinate the immune system or kill infected cells.

With one type of immunity, called sterilizing immunity, the virus never gets a chance to begin replicating and never infects a cell. Sterilizing immunity, however, is hard to achieve. More often, people achieve partial immunity, which provides a rapid response that may make the second bout of the disease less severe, or less easily transmitted to others.

It’s unclear what type of immunity people who have recovered from COVID-19 have, and only time will tell. A vaccine could possibly trigger a stronger immune response than a natural infection, although it’s yet to be seen if that will be the case for the coronavirus vaccines in trials (SN: 7/10/20).

If a person has antibodies, are they immune?

For some illnesses, like measles, antibodies may last a lifetime. But for SARS-CoV-2, the jury is still out. It’s unknown how long antibodies last in the blood, or — importantly — whether their presence is a sign of immunity. Just because a person has antibodies, it doesn’t mean they are effective at fighting the virus.

Neutralizing antibodies are ones that halt the virus in its tracks, stopping it from infecting a host cell and replicating. Such antibodies typically recognize the virus’ spike protein, which helps it break into host cells. So far, those kinds of antibodies have been a focus of studies seeking to understand whether a person may be immune.

“For the majority of people, it does appear that they are generating neutralizing antibodies,” says Aubree Gordon, an epidemiologist at the University of Michigan in Ann Arbor. “So that’s promising.”

Yet it’s still unknown what amount of neutralizing antibody is sufficient for protection. And even if they are protective, it’s unclear how long these immune proteins stick around. Studies of recovered COVID-19 patients have shown that antibodies for the coronavirus can wane after a SARS-CoV-2 infection, but overall, their levels remain relatively stable over a span of three to six months.

Because the coronavirus only began its sweep around the world at the beginning of the year, “there’s just been a limited time for people to study this,” Gordon says.

Some data suggest the immune system might not have a great memory for coronavirus infections. One study found that during a COVID-19 infection, the organ that produces memory B cells — long-lived cells that will rapidly produce antibodies if a person is re-exposed to a pathogen — doesn’t properly activate the cell types capable of becoming memory B cells. Without that immunological memory, antibodies for SARS-CoV-2 may not last very long, researchers report August 19 in Cell.

“Maybe that means that those memory responses are going to be on the short side,” says Brianne Barker, an immunologist at Drew University in Madison, N.J.

What do we know about T cells?

Studies have shown that COVID-19 patients typically develop an immune response involving T cells. Even recovered patients without a detectable antibody response have T cells in their blood, researchers report October 15 in Emerging Infectious Diseases.

But the role of T cells in infection and immune memory remains unclear. Studies have shown that memory T cells can persist in patients who were infected with the coronavirus responsible for the 2003–2004 SARS outbreak for up to 11 years after recovery. Since that virus no longer circulates, however, it’s impossible to say whether those T cells might be protective.

Some people may already have T cells that can recognize pieces of the new coronavirus (SN: 5/15/20). Those immune cells may be left over from previous exposures to coronaviruses that cause the common cold, researchers report August 4 in Science. These cross-reactive T cells might help reduce the length or severity of COVID-19 illness. On the flip side, such T cells could make the disease worse, perhaps by overstimulating the immune system and causing a condition called cytokine storm, which is behind some severe COVID-19 cases.

Can you get the coronavirus twice?

Researchers have now documented a small number of cases where people have been infected with the coronavirus twice. The first such case was reported in Hong Kong, with additional reports the United States, the Netherlands and elsewhere (SN: 8/24/20).

But it’s still unclear how common reinfections are. And with only a handful of cases so far, “we can’t really say that reinfections are telling us a whole lot at this point,” Barker says, either about immunity or whether vaccines will provide long-term protection or will need to become part of our yearly routine, like flu shots.

Some reinfections are expected; some people’s immune memory may not be potent enough to prevent the infection entirely, though it may prevent them from getting sick.

It’s hard to prove that someone has been reinfected, because researchers need to conclusively show that two different viruses caused each infection, Barker says. That requires genetic testing. What’s more, experts are not necessarily on the lookout for such cases, especially in people who are not displaying symptoms.

What does all of this mean for herd immunity?

Without knowing how long immunity lasts after an infection, and how much that varies from person to person, it’s impossible to know whether ending the pandemic through herd immunity is even possible. What is clear, experts say, is that attempting to reach herd immunity without a vaccine will lead to more illness and death.

“Promoting the concept of ‘herd immunity’ … as an answer to the COVID-19 pandemic is inappropriate, irresponsible and ill-informed,” Thomas File Jr., president of the Infectious Diseases Society of America, and Judith Feinberg, chair of the HIV Medicine Association, said in a statement October 14.

And to date, herd immunity is still far off. “Throughout the United States, we are nowhere near herd immunity,” Gordon says. “Taking the approach of herd immunity through natural infection will lead to hundreds of thousands of unnecessary deaths.”

Heating deltamethrin may help it kill pesticide-resistant mosquitoes

Mon, 19 Oct 2020 10:00:00 GMT

A few minutes in the microwave made a common insecticide about 10 times more lethal to mosquitoes in lab experiments.

The toxin deltamethrin is used around the world in home sprays and bed nets to curb the spread of mosquito-borne diseases like malaria — which kills over 400,000 people each year, according to the World Health Organization. But “mosquitoes the world over are showing resistance to deltamethrin and [similar] compounds,” says Bart Kahr, a crystallographer at New York University who has helped develop a more potent form of deltamethrin by heating it.

This form of deltamethrin may stand a better chance of killing insecticide-resistant pests, Kahr and colleagues report online October 12 in the Proceedings of the National Academy of Sciences. Malaria has been essentially eradicated in the United States, but more effective pesticides could be a boon for regions like sub-Saharan Africa, where the disease is a major public health problem.

Kahr’s team increased the potency of commercial deltamethrin dust spray simply by melting a vial of it — either by heating it to 150° Celsius in an oil bath for five minutes or by popping it in a 700-watt microwave for the same amount of time. While the microscopic deltamethrin crystals in the original spray have a haphazard structure, which looks like a jumble of misaligned flakes, the melted deltamethrin crystals solidified into starburst shapes when they cooled to room temperature.

The deltamethrin crystals in typical insecticide spray (left microscope image) contain “lots of individual leaflets that are kind of oriented in a helter-skelter manner,” says crystallographer Bart Kahr of New York University. In a new version of the spray, deltamethrin crystals are shaped more like starbursts, with fibers growing out from a single point (right).Jingxiang Yang

Chemical bonds between deltamethrin molecules in the starburst-shaped crystals are not as strong as those in the original microcrystal structure. “The molecules are intrinsically less happy, or settled, in the arrangement,” Kahr says. So, when a mosquito lands on a dusting of starburst-shaped crystals, it should be easier for deltamethrin molecules to be absorbed into the insect’s body via its feet.

The researchers tested the more potent version of deltamethrin on lab-bred mosquitoes from two species: Anopheles quadrimaculatus, which can spread malaria, and Aedes aegypti, which can transmit other life-threatening diseases, such as Zika and dengue (SN: 1/8/19). Forty mosquitoes of each species were released into petri dishes coated in the original deltamethrin dust spray, and another 40 into a dish covered in the new form of the insecticide.

That altered version of deltamethrin knocked out about half of exposed A. quadrimaculatus mosquitoes within 24 minutes. In contrast, it took nearly five hours for the original spray to knock out half of exposed Anopheles — about 12 times as long. Likewise, it took only 21 minutes for the new spray to knock out half of exposed A. aegypti, while it took the original spray over three hours.

Although A. quadrimaculatus can carry the parasite that causes malaria, this mosquito species is native to North America, where the disease is not a major public health crisis. To ensure the new type of deltamethrin would be effective in the world’s malarial hot spots, “we need to do these experiments with species called gambiae and funestus, which are the African Anopheles mosquito species,” Kahr says, as well as the six major malaria-spreading Anopheles species in South Asia.

Heat treatment for deltamethrin sprays “might increase their toxicity, but there are several obvious experiments that we would need to do before we would even think about adding this to the production system,” says Janet Hemingway of the Liverpool School of Tropical Medicine in England, who studies mosquito insecticide resistance.

First, researchers need to test the new version of the insecticide against pesticide-resistant mosquitoes. Mosquito resistance to deltamethrin, along with other chemicals in the class of synthetic pesticides known as pyrethroids, is a growing problem (SN: 6/29/12). “My prediction … is that [the insects] would be highly resistant to both forms,” Hemingway says.

Researchers also need to ensure that the more toxic form of deltamethrin is safe for people to be around, says Hemingway, who was not involved in the study. “Bottom line — interesting observation, but one that is a good distance from something that could be implemented.”

Remdesivir doesn’t reduce COVID-19 deaths, a large WHO trial finds

Fri, 16 Oct 2020 21:59:51 GMT

Remdesivir, an antiviral drug that was the first found to combat COVID-19, doesn’t reduce deaths from the disease, a large international study found.

The World Health Organization’s Solidarity trial, which combined data from 405 hospitals in 30 countries, randomly assigned more than 11,000 people hospitalized with COVID-19 to receive one of four drugs or standard care, which could include other drugs such as steroids. The tested drugs include remdesivir, the antimalaria drug hydroxychloroquine, an anti-HIV drug called lopinavir and interferon-beta1a. Interferon is an immune system chemical that triggers the body’s antiviral defenses.

None of the drugs showed any benefit in reducing deaths, the need for ventilation or the length of hospital stays, researchers report October 15 in a preliminary study posted at medRxiv.org. The work has not been vetted by other scientists yet, and some analyses may change during the peer-review process, experts say.

Other studies had already shown that neither lopinavir — given in combination with ritonavir, a drug that boosts lopinavir’s levels in the body — nor hydroxychloroquine were effective against the novel coronavirus (SN: 3/19/20; SN: 8/2/20). These studies, in addition to the new data, deliver a clear message that those drugs are not helpful for treating COVID-19, says David Brett-Major, a medical epidemiologist at the University of Nebraska Medical Center in Omaha.

But remdesivir has been shown to shave four days off of hospital stays in a trial conducted by the U.S. National Institute of Allergy and Infectious Diseases (SN: 4/29/20). In that study, the drug “showed a trend toward reducing deaths,” but the result wasn’t statistically meaningful. Preliminary results from small studies conducted by remdesivir’s maker, Gilead Sciences of Foster City, Calif., also suggested that drug might cut the chance of dying from the disease (SN: 7/13/20).

The drug currently has emergency authorization from the U.S. Food and Drug Administration for use in all hospitalized patients.

In the WHO study, 301 of 2,743 people hospitalized with COVID-19 taking remdesivir died, compared with 303 of 2,708 people in the group getting standard care. That result indicates that remdesivir doesn’t have a mortality benefit, says Helen Boucher, chief of infectious diseases at Tufts Medical Center in Boston.

But that doesn’t mean remdesivir isn’t helpful, she says. Shortening hospital stays is the reason remdesivir has been embraced, at least in the United States, Boucher says. The new WHO study aside, “the data we have now suggests it’s a four-day benefit, 11 days versus 15 days” with a placebo, she says. “That’s significant for people who are sick in the hospital.”

“I’m very comfortable as a physician recommending this medicine based on the data showing a shorter time to be better,” Boucher says.

Although the new WHO study found that remdesivir doesn’t reduce length of hospital stays, the trial was designed to show only whether the drugs could reduce the risk of dying. So its conclusions about whether remdesivir shortens hospital stays or cuts the risk of going on a ventilator need a closer look, Brett-Major says.

That’s also in part because the WHO study combined data from hundreds of hospitals in 30 countries. A closer analysis of data from individual study sites may show a clearer picture of how remdesivir performed in different settings. Hospitalization time and whether someone is put on a ventilator may also depend on other factors, such as how many hospital beds or ventilators are available. Remdesivir may still improve outcomes for individual patients in the right circumstances, Brett-Major says.

In the short term, the new study probably won’t change how remdesivir is used, says Joanne Turner, an immunologist and vice president for research at the Texas Biomedical Research Institute in San Antonio. But as more studies are done, “we’ll get clarity on when it should be used,” she says.

Many hospitalized patients, for example, are suffering more from overexuberant immune systems trying to fight off the virus. By that time, it may be too late for a drug that prevents viral replication like remdesivir to make a difference. In the WHO study, “if the drug did stop viral replication [for patients], it clearly wasn’t changing outcomes for them,” Turner says. “This will make doctors think about whether this drug is really useful in very sick people.”

But giving remdesivir to sick people earlier might help, experts say. Boucher and colleagues are part of a study testing the drug in people who are newly diagnosed with COVID-19 to see if can prevent hospitalization and severe disease.

Can supplements really help fight COVID-19? Here’s what we know and don’t know

Fri, 16 Oct 2020 18:09:43 GMT

Consumers have long turned to vitamins and herbs to try to protect themselves from disease. This pandemic is no different — especially with headlines that scream “This supplement could save you from coronavirus.”

It also helps to have celebrity enthusiasts. When President Donald Trump was diagnosed with COVID-19, his pill arsenal included Vitamin D and zinc. And in an Instagram chat with actress Jennifer Garner in September, infectious diseases expert Anthony Fauci touted vitamins C and D as ways that might generally boost the immune system. “If you’re deficient in vitamin D,” he noted, “that does have an impact on your susceptibility to infection. I would not mind recommending, and I do it myself, taking vitamin D supplements.”

But whether over-the-counter supplements can actually prevent, or even treat, COVID-19, is not clear. Since the disease is so new, researchers haven’t had much time for the kind of large experiments that provide the best answers. Instead, scientists have mostly relied on fresh takes on old data. Some studies have looked at outcomes of patients who routinely take certain supplements — and found some promising hints. But so far there’s little data from the kinds of scientifically rigorous experiments that give doctors confidence when recommending supplements.

Here’s what we know today about three supplements getting plenty of attention around COVID-19.

Vitamin D

What it is: Called “the sunshine vitamin” because the body makes it naturally in the presence of ultraviolet light, Vitamin D is one of the most heavily studied supplements (SN: 1/27/19). Certain foods, including fish and fortified milk products, are also high in the vitamin.

Why it might help: Vitamin D is a hormone building block that helps strengthen the immune system.

How it works for other infections: In 2017, the British Medical Journal published a meta-analysis that suggested a daily vitamin D supplement might help prevent respiratory infections, particularly in people who are deficient in the vitamin.

But one key word here is deficient. That risk is highest during dark winters at high latitudes and among people with more color in their skin (melanin, a pigment that’s higher in darker skin, inhibits the production of vitamin D).

“If you have enough vitamin D in your body, the evidence doesn’t stack up to say that giving you more will make a real difference,” says Susan Lanham-New, head of the Nutritional Sciences Department at the University of Surrey in England.

And taking too much can create new health problems, stressing certain internal organs and leading to a dangerously high calcium buildup in the blood. The recommended daily allowance for adults is 600 to 800 International Units per day, and the upper limit is considered to be 4,000 IUs per day.

What we know about Vitamin D and COVID-19: Few studies have looked directly at whether vitamin D makes a difference in COVID.

In May, in the BMJ Nutrition, Prevention & Health, Lanham-New and her colleagues published a summary of existing evidence and concluded that there’s only enough to recommend vitamin D to help with COVID-19 prevention for people who are deficient. That paper made inferences from how vitamin D works against other respiratory tract infections and immune health.

More than a dozen studies are now testing vitamin D directly for prevention and treatment, including a large one led by JoAnn Manson, a leading expert on vitamin D. An epidemiologist and preventive medicine physician at Harvard Medical School and Brigham & Women’s Hospital in Boston. That study will analyze if vitamin D can affect the course of a COVID-19 infection. The trial aims to recruit 2,700 people across the United States with newly diagnosed infections, along with their close household contacts.

The goal is to determine whether newly diagnosed people given high doses of vitamin D — 3,200 IU per day — are less likely than people who get a placebo to experience severe symptoms and need hospitalization. “The biological plausibility for a benefit in COVID is compelling,” she says, given the nutrient’s theoretical ability to impede the severe inflammatory reaction that can follow coronavirus infection. “However the evidence is not conclusive at this time.”

Zinc

What it is: Zinc, a mineral found in cells all over the body, is found naturally in certain meats, beans and oysters.

Why it might help: It plays several supportive roles in the immune system, which is why zinc lozenges are always hot sellers in cold and flu season. Zinc also helps with cell division and growth.

How it works for other infections: Studies of using zinc for colds — which are frequently caused by coronaviruses — suggest that using a supplement right after symptoms start might make them go away quicker. That said, a clinical trial from researchers in Finland and the United Kingdom, published in January in BMJ Open did not find any value for zinc lozenges for the treatment of colds. Some researchers have theorized that inconsistences in data for colds may be explained by varying amounts of zinc released in different lozenges.

What we know about zinc and COVID-19: The mineral is promising enough that it was added to some early studies of hydroxychloroquine, a drug tested early in the pandemic. (Studies have since shown that hydroxychloroquine can’t prevent or treat COVID-19 (SN: 8/2/20).)

In July, researchers from Aachen University in Germany wrote in Frontiers of Immunology that current evidence “strongly suggests great benefits of zinc supplementation” based on looking at similar infections including SARS, another disease caused by a coronavirus. For example, studies suggest that giving zinc reduces the risk for death from a pneumonia infection. The researchers cite evidence that zinc might help prevent the virus from entering the body, and help slow the virus’s replication when it does.

Another review — also based on indirect evidence — published August 1 in Advances in Integrative Medicine also concluded that zinc might be helpful in people who are deficient.

In September, researchers from Hospital Del Marin Barcelona reported that among 249 patients studied, those who survived COVID had higher zinc levels in their plasma (an average of 63.1 mcg/dl) than those who died (43mcg/dl).

Overall, though, the jury is still out, says Suma Thomas, a cardiologist at the Cleveland Clinic Foundation, who in June led a team that reviewed the evidence for popular supplements in the Cleveland Clinic Journal of Medicine. Given what’s already known, zinc could possibly decrease the duration of infection but not the severity of symptoms, she said, particularly among people who are deficient. About a dozen studies are now looking at zinc for COVID treatment, often with other drugs or supplements.

Thomas and her colleagues are comparing symptom severity and future hospitalization in COVID-19 patients who take zinc with and without high doses of vitamin C with those who receive ordinary care without the supplement. Results are expected soon, she says.

Vitamin C

What it is: Also called L-ascorbic acid, vitamin C has a long list of roles in the body. It’s found naturally in fruits and vegetables, especially citrus, peppers and tomatoes.

Why it might help: It’s a potent antioxidant that’s important for a healthy immune system and preventing inflammation.

How it works for other infections: Thomas cautions that the data on vitamin C are often contradictory. One review from Chinese researchers, published in February in the Journal of Medical Virology, looked at what is already known about vitamin C and other supplements that might have a role in COVID-19 treatment. Among other encouraging signs, human studies find a lower incidence of pneumonia among people taking vitamin C, “suggesting that vitamin C might prevent the susceptibility to lower respiratory tract infections under certain conditions.”

But for preventing colds, a 2013 Cochrane review of 29 studies didn’t support the idea that vitamin C supplements could help in the general population. However, the authors wrote, given that vitamin C is cheap and safe, “it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial.”

What we know about Vitamin C and COVID-19: About a dozen studies are under way or planned to examine whether vitamin C added to coronavirus treatment helps with symptoms or survival, including Thomas’ study at the Cleveland Clinic.

In a review published online in July in Nutrition, researchers from KU Leuven in Belgium concluded that the vitamin may help prevent infection and tamp down the dangerous inflammatory reaction that can cause severe symptoms, based on what is known about how the nutrient works in the body.

Melissa Badowski, a pharmacist who specializes in viral infections at the University of Illinois at Chicago College of Pharmacy and colleague Sarah Michienzi published an extensive look at all supplements that might be useful in the coronavirus epidemic. There’s still not enough evidence to know whether they are helpful, the pair concluded in July in Drugs in Context. “It’s not really clear if it’s going to benefit patients,” Badowski says.

And while supplements are generally safe, she adds that nothing is risk free. The best way to avoid infection, she says, is still to follow the advice of epidemiologists and public health experts: “Wash your hands, wear a mask, stay six feet apart.”

Turning space images into music makes astronomy more accessible

Fri, 16 Oct 2020 10:00:00 GMT

Put into music, telescope observations of the center of the Milky Way create a tranquil tune, glittering with xylophone and piano notes. The iconic Pillars of Creation in the Eagle Nebula, meanwhile, sound like an eerie sci-fi score. And the supernova remnant Cassiopeia A is a sweeping symphony.

These musical renditions, or sonifications, were released on September 22 by NASA’s Chandra X-ray Center. “Listening to the data gives [people] another dimension to experience the universe,” says Matt Russo, an astrophysicist and musician at the astronomy outreach project SYSTEM Sounds in Toronto.

Sonification can make cosmic wonders more accessible to people with blindness or visual impairments, and complement images for sighted learners. SYSTEM Sounds teamed up with Kimberly Arcand, a visualization scientist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., to create the new pieces.

Christine Malec, a musician and astronomy enthusiast who is blind, vividly recalls the first sonification she ever heard — a rendering of the TRAPPIST-1 planetary system that Russo played during a planetarium show in Toronto (SN: 2/22/17). “I had goosebumps, because I felt like I was getting a faint impression of what it’s like to perceive the night sky, or a cosmological phenomenon,” she says. Music affords data “a spatial quality that astronomical phenomena have, but that words can’t quite convey.”

The new renditions combine data from multiple telescopes tuned to different types of light. The sonification of an image of the Milky Way’s center, for instance, includes observations from the Chandra X-ray Observatory, optical images from the Hubble Space Telescope and infrared observations from the Spitzer Space Telescope. Users can listen to data from each telescope alone or the trio in harmony.

New data “sonifications” translate telescope images into songs. Listen to observations of celestial objects around the Milky Way, from the galactic center to the star-forming Pillars of Creation in the Eagle Nebula.

As a cursor pans from left to right across the image of the galactic center, showing a 400-light-year expanse, Chandra X-ray observations, played on the xylophone, trace filaments of superhot gas. Hubble observations on the violin highlight pockets of star formation, and Spitzer’s piano notes illuminate infrared clouds of gas and dust. Light sources near the top of the image play at higher pitches, and brighter objects play louder. The song crescendos around a luminous region in the lower-right corner of the image, where glowing gas and dust shroud the galaxy’s supermassive black hole.

Layering the instruments on top of each other gives the observations an element of texture, Malec says. “It appealed to my musical sense, because it was done in a harmonious way — it was not discordant.”

That was on purpose. “We wanted to create an output that was not just scientifically accurate, but also hopefully nice to listen to,” Arcand says. “It was a matter of making sure that the instruments played together in symphony.”

But discordant sounds can also can be educational, Malec says. She points to the new sonification of supernova remnant Cassiopeia A: The sonification traces chemical elements throughout this great plume of celestial debris using notes played on stringed instruments (SN: 2/19/14). Those notes make a pretty harmony, but they can be difficult to tell apart, Malec says. “I would have picked very different instruments” to make it easier for the ear to follow — perhaps a violin paired with a trumpet or an organ.

While sonification is a valuable tool to get the public interested in astronomy, it also has untapped potential to help professional astronomers analyze data, says Wanda Díaz-Merced, an astronomer who is also at the Harvard-Smithsonian Center for Astrophysics but was not involved in the project (SN: 10/22/14).

Astronomers including Díaz-Merced, who is blind, have used sonifications to study stars, solar wind and cosmic rays. And in experiments, Díaz-Merced has demonstrated that sighted astronomers can better pick out signals in datasets by analyzing audio and visual information together rather than relying on vision alone.

Still, efforts to sonify astronomy datasets for research have been rare. Making data sonification a mainstream research method would not only break down barriers to pursuing astronomy research, but may also lead to many new discoveries, she says.

The FDA has approved the first treatment for Ebola

Thu, 15 Oct 2020 16:48:30 GMT

There is now an approved treatment for Ebola, one of the world’s deadliest diseases.

The U.S. Food and Drug Administration announced October 14 that Inmazeb, a cocktail of lab-made antibodies developed by the pharmaceutical company Regeneron, can be used to treat adult and pediatric patients with Ebola. The announcement comes less than a year after the FDA greenlit the first Ebola vaccine (SN: 12/20/19).

“This is a big development,” says Erica Ollmann Saphire, an immunologist at the La Jolla Institute for Immunology in San Diego, Calif. Ebola virus causes severe illness, including fever, vomiting, diarrhea and bleeding. Outbreaks of the disease, discovered in the 1970s, can kill 25 to 90 percent of those infected (SN: 2/11/19). Previously, people could only be helped by supportive therapies, like replacing lost fluids, Saphire says. “But this approval means Ebola is now a treatable disease.”

Inmazeb was evaluated along with three other experimental Ebola treatments in a clinical trial conducted in the Congo in 2018 and 2019 amid the second largest outbreak of the disease (SN: 8/12/19). During the trial, 33.8 percent of people treated with Inmazeb died after 28 days, compared with 51 percent of people who received a different treatment.

The drug consists of three different monoclonal antibodies, human-made antibodies designed to mimic those produced naturally during an immune response. One gums up structures on the Ebola virus that allow it to infiltrate human cells, while the other two recruit immune cells to clear out the virus and infected cells.

Saphire, who heads a research consortium focused on studying antibody treatments for Ebola, says that given the drug’s two-pronged approach to fighting the virus, “the Regeneron cocktail is exactly the sort of complementary approach our research predicted would be most efficacious.” (Regeneron Pharmaceuticals is a major financial supporter of the Society for Science & the Public, which publishes Science News.)

Inmazeb, which is delivered intravenously, has been used to treat patients in the ongoing Ebola outbreak in the Congo under compassionate use protocols. The new FDA approval will remove regulatory hurdles, Saphire says, allowing local doctors and medical aid groups like Doctors Without Borders to more easily obtain the drug from national stockpiles in the United States and deploy them in affected areas.

In July, Regeneron and the U.S. Biomedical Advanced Research and Development Authority announced an agreement whereby the company would produce Inmazeb for a national stockpile over the next six years.