A new analysis of nearly a quarter million stars puts firm ages on the most momentous pages from our galaxy’s life story.

Far grander than most of its neighbors, the Milky Way arose long ago, as lesser galaxies smashed together. Its thick disk — a pancake-shaped population of old stars — originated remarkably soon after the Big Bang and well before most of the stellar halo that envelops the galaxy’s disk, astronomers report March 23 in Nature.

“We are now able to provide a very clear timeline of what happened in the earliest time of our Milky Way,” says astronomer Maosheng Xiang.
He and Hans-Walter Rix, both at the Max Planck Institute for Astronomy in Heidelberg, Germany, studied almost 250,000 subgiants — stars that are growing larger and cooler after using up the hydrogen fuel at their centers. The temperatures and luminosities of these stars reveal their ages, letting the researchers track how different epochs in galactic history spawned stars with different chemical compositions and orbits around the Milky Way’s center.

“There’s just an incredible amount of information here,” says Rosemary Wyse, an astrophysicist at Johns Hopkins University who was not involved with the study. “We really want to understand how our galaxy came to be the way it is,” she says. “When were the chemical elements of which we are made created?”

Xiang and Rix discovered that the Milky Way’s thick disk got its start about 13 billion years ago. That’s just 800 million years after the universe’s birth. The thick disk, which measures 6,000 light-years from top to bottom in the sun’s vicinity, kept forming stars for a long time, until about 8 billion years ago.

During this period, the thick disk’s iron content shot up 30-fold as exploding stars enriched its star-forming gas, the team found. At the dawn of the thick disk era, a newborn star had only a tenth as much iron, relative to hydrogen, as the sun; by the end, 5 billion years later, a thick disk star was three times richer in iron than the sun.

Xiang and Rix also found a tight relation between a thick disk star’s age and iron content. This means gas was thoroughly mixed throughout the thick disk: As time went on, newborn stars inherited steadily higher amounts of iron, no matter whether the stars formed close to or far from the galactic center.

But that’s not all that was happening. As other researchers reported in 2018, another galaxy once hit our own, giving the Milky Way most of the stars in its halo, which engulfs the disk (SN: 11/1/18). Halo stars have little iron.

The new work revises the date of this great galactic encounter: “We found that the merger happened 11 billion years ago,” Xiang says, a billion years earlier than thought. As the intruder’s gas crashed into the Milky Way’s gas, it triggered the creation of so many new stars that our galaxy’s star formation rate reached a record high 11 billion years ago.

The merger also splashed some thick disk stars up into the halo, which Xiang and Rix identified from the stars’ higher iron abundances. These “splash” stars, the researchers found, are at least 11 billion years old, confirming the date of the merger.

The thick disk ran out of gas 8 billion years ago and stopped making stars. Fresh gas around the Milky Way then settled into a thinner disk, which has given birth to stars ever since — including the 4.6-billion-year-old sun and most of its stellar neighbors. The thin disk is about 2,000 light-years thick in our part of the galaxy.

“The Milky Way has been quite quiet for the last 8 billion years,” Xiang says, experiencing no further encounters with big galaxies. That makes it different from most of its peers.

If the thick disk really existed 13 billion years ago, Xiang says, then the new James Webb Space Telescope (SN: 1/24/22) may discern similar disks in galaxies 13 billion light-years from Earth — portraits of the Milky Way as a young galaxy.

A fierce group of predatory dinosaurs may have done much of their hunting in the water.

An analysis of the bone density of several sharp-toothed spinosaurs suggests that several members of this dino group were predominantly aquatic, researchers report March 23 in Nature.

That finding is the latest salvo in an ongoing challenge to the prevailing view that all dinosaurs were land-based animals that left the realms of water and air to marine reptiles such as Mosasaurus and flying reptiles such as Pteranodon. But, other researchers say, it still doesn’t prove that Spinosaurus and its kin actually swam.
Back in 2014, Nizar Ibrahim, a vertebrate paleontologist now at the University of Portsmouth in England, and colleagues pieced together the fossil of a 15-meter-long Spinosaurus from what’s now Morocco. The dinosaur’s odd collection of features — a massive sail-like structure on its back, short and muscular legs, nostrils set well back from its snout and needlelike teeth seemingly designed for snagging fish — suggested to the researchers that the predator might have been a swimmer (SN: 9/11/14). In particular, it had very dense leg bones, a feature of some aquatic creatures like manatees that need the bones for ballast to stay submerged.

In the new study, Ibrahim and his team returned to that question of bone density to assess whether it’s a reliable proxy for how much time a creature spends in the water. The team assembled “a massive dataset” of femur and dorsal rib bone densities from “an incredible menagerie of extinct and living animals, reaching out to museum curators all around the world,” Ibrahim says.

That menagerie includes spinosaurs like showy, sail-backed Spinosaurus as well as its equally sharp-toothed cousins Baryonyx and Suchomimus. It also includes other groups of dinosaurs, extinct marine reptiles, pterosaurs, birds, modern crocodiles and marine mammals.

The team then compared these bone analyses with the water-dwelling habits of the various creatures in the study. That work confirms that density is “an excellent indicator” for species in the early stages of a transition from land-dwelling to water-dwelling, the team reports. Those compact bones can aid such transitional creatures, which might not yet have features like fins or flippers to help them maneuver in the water more easily, in hunting underwater — what the team calls “subaqueous foraging.”

The analyses also show that not only did Spinosaurus have very dense bones, but Baryonyx did too. That suggests that both of these dinos were subaqueous foragers, the team says. That idea builds on previous work by Ibrahim and colleagues that proposed that Spinosaurus didn’t just spend much of its time in the water, but could actually swim in pursuit of prey, thanks to its odd, paddle-shaped tail (SN: 4/29/20).
The idea of a swimming Spinosaurus hasn’t been convincing to all. In 2021, a study in Palaeontologia Electronica examined Spinosaurus’ anatomy in detail and came to a different conclusion. The dinosaur was not a highly specialized aquatic predator, wrote David Hone, a zoologist and paleobiologist at Queen Mary University of London, and Thomas Holtz Jr., a vertebrate paleontologist at the University of Maryland in College Park. Instead, Spinosaurus may have just waded in the shallows, heronlike, to do its fishing.

The new study has not convinced those skeptics. Spinosaurus has “clearly got very dense bones. This is really good evidence that they’re hanging around in water — but we kind of knew that,” Hone says. “It’s not clear what they’re doing in the water. That’s the contentious part.”

Take hippos, which spend much of their time mostly submerged, Hone says. “Hippos have bone densities entirely comparable to Spinosaurus and Baryonyx, but they don’t eat in the water” and they don’t swim, he adds.

“Everyone has been in agreement that Spinosaurus was more aquatic than other big theropods” like Tyrannosaurus rex, Holtz says. That Baryonyx also had dense bones was a bit of an interesting surprise, he adds.

But dense bones or not, Holtz says, “it still doesn’t turn them into aquatic hunters.” He describes several anatomical features — Spinosaurus’ long slender neck, tilted head and arrangement of neck muscles that suggest a downward striking motion — that point more to a wading creature that hunted from above the water surface than one that chased its prey underwater.

Kiersten Formoso, a vertebrate paleobiologist at the University of Southern California in Los Angeles, says that the new comparison of bone densities among a wide variety of creatures is a valuable addition, one that she anticipates referring to in her own work studying the transition of ancient creatures from land to water. But she too is not convinced that it proves that Spinosaurus and Baryonyx could actually swim.

“I would never detach Spinosaurus from the water,” Formoso says. But, she adds, more work needs to be done on its biomechanics — how it might have moved — to understand how adroitly aquatic the dinosaur might have been.

Smoke rings are being seen in a new light.

Doughnut-shaped structures called vortex rings are sometimes seen swirling through fluids. Smokers can form them with their mouths, volcanoes can spit them out during eruptions and dolphins can blow them as bubble rings. Now, scientists can create the rings with light.

A standard vortex is an eddy in a liquid or gas, like a whirlpool (SN: 3/5/13). Imagine taking that swirling eddy, stretching it out and bending it into a circle and attaching it end-to-end. That’s a vortex ring. These rings travel through the liquid or gas as they swirl — for example, smoke rings float through the air away from a smoker’s head. In the new vortex rings, described June 2 in Nature Photonics, light behaves similarly: The flow of energy swirls as the ring moves.
Optics researcher Qiwen Zhan and colleagues started from a vortex tube, a hurricanelike structure they already knew how to create using laser light. The team used optics techniques to bend the tube into a circular shape, creating a vortex ring.

The light rings aren’t that different from smoke or bubble rings, says Zhan, of the University of Shanghai for Science and Technology. “That’s kind of cool.”

Zhan is interested in seeing whether scientists could create vortex rings out of electric current or a magnetic field. And further study of the light rings might help scientists better understand how topology — the geometry of doughnuts, knots and similar shapes — affects light and how it interacts with matter.

Samples of the asteroid Ryugu are the most pristine pieces of the solar system that scientists have in their possession.

A new analysis of Ryugu material confirms the porous rubble-pile asteroid is rich in carbon and finds it is extraordinarily primitive (SN: 3/16/20). It is also a member of a rare class of space rocks known as CI-type, researchers report online June 9 in Science.

Their analysis looked at material from the Japanese mission Hayabusa2, which collected 5.4 grams of dust and small rocks from multiple locations on the surface of Ryugu and brought that material to Earth in December 2020 (SN: 7/11/19; SN: 12/7/20). Using 95 milligrams of the asteroid’s debris, the researchers measured dozens of chemical elements in the sample and then compared abundances of several of those elements to those measured in rare meteorites classified as CI-type chondrites. Fewer than 10 meteorites found on Earth are CI chondrites.
This comparison confirmed Ryugu is a CI-type chondrite. But it also showed that unlike Ryugu, the meteorites appear to have been altered, or contaminated, by Earth’s atmosphere or even human handling over time. “The Ryugu sample is a much more fresh sample,” says Hisayoshi Yurimoto, a geochemist at Hokkaido University in Sapporo, Japan.

The researchers also measured the abundances of manganese-53 and chromium-53 in the asteroid and determined that melted water ice reacted with most of the minerals around 5 million years after the solar system’s start, altering those minerals, says Yurimoto. That water has since evaporated, but those altered minerals are still present in the samples. By studying them, the researchers can learn more about the asteroid’s history.

A few weeks ago, I was obsessed with my nose and throat. I was on a trip to Seattle to speak at a small, masks-required virology meeting about being a journalist during a pandemic. I went to graduate school there, so I was thrilled to see old friends and colleagues. But the irony that I was risking getting infected amid rising COVID-19 cases to get on a plane to talk with virologists about the pandemic didn’t escape me. I spent the whole week on high alert for the slightest hint of a sore throat or a runny nose. Despite masking, I worried that I’d get sick and be stuck thousands of miles from home or that I’d unknowingly pass the virus on to someone else.

Luckily, this story has a happy ending. I didn’t catch the coronavirus. None of my friends or former colleagues got sick. Although I didn’t escape completely unscathed; I did come down with a mystery, non-COVID cold that I suspect I caught from a friend’s baby. Still, the experience made me wonder ​​— what if I didn’t have to worry so much about becoming a disease spreader because there were COVID-19 vaccines that helped my body control the virus in my nose?
Researchers are working on vaccines that would hopefully do just that. You squirt these vaccines into your nostrils, rather than inject them into your arm muscle like the current COVID-19 shots. Sprayed up the nose, the vaccines teach our immune systems to fortify our nostrils against coronavirus, perhaps meaning we get less sick or making us less likely to transmit the virus to other people.

Jabs in the arm may not be as good at preventing transmission as nasal spray vaccines, some scientists suspect. The shots are better at building defenses that circulate in the blood or fluid that surrounds cells, which makes them great at protecting the lungs. And they have done what they are designed to do: curb severe disease and death (SN: 8/31/21). Booster doses help fend off severe COVID-19 better than the first two shots — especially for older people, studies show (SN: 4/29/22). But even with death rates down, that doesn’t mean our fight with coronavirus is over. Waning immune defenses combined with slippery versions of the coronavirus that can evade parts of our immune systems leave vaccinated people susceptible to infection. So we still need additional protection.

A panel of experts advising the U.S. Food and Drug Administration will meet later this month to weigh in on whether we might need a vaccine update for the fall. Updated shots may indeed be on the horizon: Preliminary data from vaccine developer Moderna show that its latest vaccine, which includes both omicron and the original virus, boosts the immune response against omicron as well as other variants such as delta, the company announced on June 8.

And on June 7 the FDA advisory committee recommended that the agency authorize a new COVID-19 vaccine for emergency use. This one, developed by the company Novavax, is based on a traditional method — showing the immune system purified viral proteins — which may be appealing to still unvaccinated people who are hesitant about the novel mRNA technology in Moderna’s and Pfizer’s shots (SN: 1/28/21). Other experts are working on vaccines that might hold up against an onslaught of variants, both present and future.
And then, there are the nasal spray vaccines. They could not only protect our lungs, but also the mucous membranes that line the upper regions of our respiratory tracts such as the nose. Such sprays would give us not only a motion detector ready to sense an intruder in an inner room of a building but also an alarm system that goes off the second the front door opens.

That type of alarm system isn’t a brand-new tool. For example, there is a nasal influenza vaccine available in the United States called FluMist, which teaches the body to recognize four different strains. And there is a similar one in Europe called Fluenz Tetra. Each flu virus included in these vaccines is weakened but can replicate in the body. The attenuated viruses grow best at cooler temperatures found in our noses, not the warm environment of our lungs, a barrier that keeps them from making it to the lungs and causing influenza. But by taking off in the nose, replicating viruses kick off an immune response, so our bodies learn to set up reinforcements there.

Already roughly a dozen potential COVID-19 nasal vaccines have made it to clinical trials around the world. One developed by a company called Altimmune was abandoned after early results showed the vaccine didn’t prompt a good immune response in healthy participants. Others have shown promise when tested in animals.

The prospect of having nasal vaccines that may be able to curb transmission better than existing shots is understandably exciting. But these types of vaccines still have a way to go before hitting local pharmacies or doctors’ offices.

First, it’s crucial for the nasal vaccines to strike the right balance. Their sprays must be strong enough to provoke our immune systems, but still weak enough that there aren’t unwelcome symptoms or side effects. It’s also of course important to ensure the safety of vaccine candidates that include live, weakened viruses.
Some nasal vaccine candidates are similar to the influenza vaccine and include live, weakened viruses. Most of these viruses aren’t the coronavirus itself, but rather harmless-to-human viruses that sport one coronavirus protein for our bodies to recognize. Others may not need a virus to grow in the body to work. One team is developing a nasal spray that includes only the coronavirus spike protein, which helps the virus break into cells. That spike spray could serve as a boost for people who received one of the mRNA vaccines, coaxing important immune cells to come live in the nose and other parts of the respiratory tract. Once there, those immune cells would be poised to kick into high gear if the coronavirus invades.

Second, nasal sprays face the same problem as current COVID-19 vaccines. What happens when the virus evolves in ways that help it hide from our immune system? We’ve already seen the consequences of that thanks to the delta and omicron waves that raced around the globe. And from 2016 to 2018, FluMist stumbled in the face of tweaked versions of some influenza viruses. Experts recommended that people get a different type of flu shot in those seasons. Just as researchers are considering updating existing COVID-19 shots to better mimic the viral variants currently wreaking havoc, nasal vaccines may also need regular updating.

If I had a choice, I would never catch coronavirus. But in the grand scheme of things, it’d be nice if a spray up my nose could drastically lower my chances of passing it on to someone else if I did get infected. If they make it to consumers, the nasal vaccines could make future COVID-19 waves much smaller than they are now. And after more than two years of navigating ever-larger waves, wouldn’t that be nice?

In my opinion, the most satisfying science documentary TV series ever made was a 1970s British production called Connections. Hosted by impish historian James Burke, wearing bell-bottoms and thick-framed tortoiseshell glasses, each episode revealed how one small innovation from earlier human civilizations led to another and then another and another, culminating in the invention of some ultramodern (for the 1970s) technology.

Watching these pieces of the past come together was deeply gratifying, if not a little dizzying. The present is so familiar that it feels inevitable. But it was striking to see modern civilization, even modern humans, in context, to recognize how all that we are now actually hinges on countless moments of invention, improvement and experimentation in the deep past.

I had a similar reaction to The Rise and Reign of the Mammals, paleontologist Steve Brusatte’s sweeping history of the animals that have, for the moment, inherited the Earth. Moving generally forward in time, the book describes how the mammalian line progressively acquired a range of features that have come to define what a mammal is.

Some of the moments of evolutionary invention that led to what we now think of as a mammal are remarkably subtle. There’s the hard roof of the mouth that created a dedicated airway to the lungs, allowing mammal ancestors to eat and breathe at the same time. There’s the change from a spine that bends from left to right (which produces the classically reptilian side-to-side gait) to one that enables bending up and down, which ultimately allowed mammals to take in more oxygen as they moved, helping them run faster. And there’s the variety of tooth shapes — incisors, canines, premolars and molars — that made it possible for mammals to eat many kinds of food. A reptile, by contrast, tends to have just one tooth type.

Some mammalian characteristics are very familiar: milk production, warm-bloodedness, hair. But there’s one less–well-known evolutionary advance that was in its humble way quite profound, setting “us apart from amphibians, reptiles, and birds,” Brusatte writes. It’s a joint in the jaw that makes chewing possible (SN: 8/17/19, p. 8). The ability to chew was “a major evolutionary turning point,” he writes. “It triggered a domino chain of changes to mammalian feeding, intelligence, and reproduction.”
Brusatte also describes a second small, curious adaptation: the transformation of two bones in the reptile jaw, which migrated to the inner ear to become two members of a famous trio, the hammer and anvil (the third is the stirrup). These inner ear bones are the basis for yet another key mammalian feature: the ability to hear a wide range of frequencies, particularly in the upper register (SN Online: 12/6/19).

The story of the Age of Mammals is often told as the flip side to the dinosaurs’ demise. But the fossil record reveals that mammals were hardly newcomers: They arose around the same time as the dinosaurs, over 200 million years ago. Even during the Age of Dinosaurs, “in the smaller and hidden niches, it was already the Age of Mammals,” Brusatte writes. “Mammals were better than the dinosaurs at being small.”

Within just a few hundred thousand years of the asteroid impact that wiped out all nonbird dinos some 66 million years ago, mammals moved in to fill the vacancy, rapidly getting a lot bigger, ballooning from, say, mouse-sized to beaver-sized (SN: 12/7/19, p. 32). Pretty soon, they got a lot smarter too. In a geologic blink — a scant 10 million years — mammals’ brains caught up with their brawn, and then the Age of Mammals was off to the races (SN: 5/7/22 & 5/21/22, p. 18).

Paleontology narratives often require refocusing a story’s lens in a way that can be jarring, zooming out to encompass Earth-wide climate cataclysms and mass extinctions and then in again to describe tiny bones and obscure species. Brusatte, though, is a nimble storyteller and he’s chosen an engrossing story to tell.

As a science writer, I often find myself focusing on minute advances, studying tiny threads. So it’s satisfying to sit back and admire the full tapestry as presented in The Rise and Reign of the Mammals. Reading this book reminded me what I most enjoy about geology, paleontology and the evolution of life on Earth: This planet has got some epic stories.

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Earthquakes have rocked the planet for eons. Studying the quakes of old could help scientists better understand modern tremors, but tools to do such work are scarce.

Enter zircons. Researchers used the gemstones to home in on the temperatures reached within a fault during earthquakes millions of years ago. The method offers insights into the intensity of long-ago quakes, and could improve understanding of how today’s tremors release energy, the researchers report in the April Geochemistry, Geophysics, Geosystems.
“The more we understand about the past, the more we can understand what might happen in the future,” says Emma Armstrong, a thermochronologist at Utah State University in Logan.

Armstrong and colleagues focused on California’s Punchbowl Fault. That now-quiet portion of the larger San Andreas Fault was probably active between 1 million to 10 million years ago, Armstrong says.

Heat from friction is generated in a fault when it slips and triggers an earthquake. Previous analyses of preserved organic material suggested that temperatures within the Punchbowl Fault peaked between 465° Celsius and 1065° C. The researchers suspected that zircons in rocks from the fault could narrow that broad window.

Zircons often contain the radioactive chemical elements uranium and thorium, which decay to helium at a predictable rate (SN: 5/2/22). That helium then builds up in the crystals. But when a zircon is heated past a temperature threshold — the magnitude of which depends on the zircon’s composition — the accumulated helium escapes.

Measuring the amounts of the three elements in zircons from the fault suggests that the most intense earthquake generated temperatures lower than 800° C. That roughly halves the range previously reported. The finding provides clues to the amount of heat released by quakes, something difficult to measure for modern tremors because they often occur at great depths.

Armstrong plans to continue studying zircons, in the hopes of finding more ways to exploit them for details about ancient quakes.

Turns out there is rest for the wicked: Sleepy mosquitoes are more likely to catch up on missed z’s than drink blood, a new study finds.

Most people are familiar with the aftermath of a poor night’s sleep. Insects also suffer; for instance, drowsy honeybees struggle to perform their signature waggle dance, and weary fruit flies show signs of memory loss. In the case of sleep-deprived mosquitoes, they give up valuable time for feeding in favor of sleeping overtime, researchers report June 1 in Journal of Experimental Biology.
The preference for dozing over dining is surprising given that “we know that mosquitoes love blood a lot,” says Oluwaseun Ajayi, a disease ecologist at the University of Cincinnati.

Scientists have long been interested in mosquitoes’ circadian rhythms, the internal clock that determines their sleep and awake times (SN: 10/2/17). Knowing when a mosquito is awake — and biting — is important for understanding and limiting disease transmission. For instance, malaria, often transmitted by nocturnal mosquitoes, is kept under control by slinging netting around beds. But new research suggests that mosquitoes that feed during the day may also spread the disease.

It’s challenging to study sleeping bloodsuckers in the lab. That’s partly because awake mosquitoes are aroused by the presence of a meal — the experimenter. And when mosquitoes do fall asleep, they look rather similar to peers that are merely resting to conserve energy.

That’s the tricky — and often species-specific — question: “How can you tell [when] an insect is sleeping?” says Samuel Rund, a mosquito circadian biologist at the University of Notre Dame in Indiana who was not involved in the research.

One way to tell is by tracking the insect’s behavior. So Ajayi and colleagues watched mosquitoes sleep. The team focused on three species known to carry diseases, including malaria: Aedes aegypti, which are active during the day; Culex pipiens, which prefer dusk; and the nocturnal Anopheles stephensi. The mosquitoes were left alone in a room in small enclosures, where the team used cameras and infrared sensors to spy on them.

After about two hours, the mosquitoes appeared to nod off. Their abdomens lowered to the ground and their hind legs drooped, the footage showed. As time went on, C. pipiens and A. aegypti showed a reduced response when the experimenter walked in the room, suggesting a tasty smell was less likely to wake those species when in a deep sleep. Taken together, the change in posture, periods of inactivity and lower arousal were determined to identify a snoozing mosquito.

What started as a relaxing experiment for the mosquitoes quickly changed gears. The insects were placed in clear tubes that received vibration pulses every few minutes, preventing them from falling into deep sleep. After four to 12 hours of this sleep deprivation, the team mimicked the presence of a host with a pad of heated artificial sweat. In another experiment, a plucky human volunteer offered up a leg to be fed on for five minutes by sleep-deprived and well-rested A. aegypti in batches of 10 insects.

In both cases, the mosquitoes that had had a full night’s rest were much more likely to land on the host than those that had been deprived of sleep. And the leg exposed to sleepy mosquitoes fared much better than when it was exposed to the control group: In eight tests, on average 77 percent of the well-rested mosquitoes went for a blood meal, compared with only 23 percent of sleepy mosquitoes.

The findings, Rund says, open avenues for research into controlling mosquito populations and reducing disease using the insects’ circadian rhythms.

The fading of a once-vibrant yellow rose reveals how the ravages of time and chemical alteration can dampen the visual power of a painting.

Most of the flowers in Abraham Mignon’s 17th century painting Still Life with Flowers and a Watch seem to leap off the canvas. But one yellow rose, painted with arsenic sulfide–based orpiment pigment, is a flat, jarring element. That wasn’t Mignon’s intention: The rose lost its luster due to the chemical transformation of some of its original bright pigment into colorless lead arsenates, researchers report June 8 in Science Advances.
Paintings conservator Nouchka De Keyser of the Rijksmuseum in Amsterdam and colleagues analyzed the rose using noninvasive techniques including X-ray fluorescence imaging and X-ray powder diffraction (SN: 10/1/21). The team first mapped the lingering traces of arsenic, lead, calcium and other chemical elements in the layers of paint to reveal how Mignon carefully layered paint to create a nearly three-dimensional rose out of light and shadow.

The analyses also revealed two newer crystals on the rose containing both lead and arsenic. Called mimetite and schultenite, the crystals are the product of a series of chemical reactions. First, the reaction of orpiment with light created a highly mobile type of arsenic called arsenolite. That mobilized arsenolite then found its way to an underlying layer of lead white paint and chemically reacted with it to produce the mimetite and schultenite. The crystals lack the bright color of the orpiment — instead, they are colorless and flatten the flower’s appearance.
Science can’t turn back the clock on the chemical transformation to restore the rose’s erstwhile glory — that’s a one-way street. But digital reconstructions made using similar techniques as in the new study could offer several benefits and not just to scientists and art historians, De Keyser says. Not only can such reconstructions reveal now-faded elements in other paintings — they might also appear in museums, allowing visitors a ghostly glimpse of a painting’s true past.

For the last two years, a person acting erratically in downtown Denver has likely first encountered unarmed health care workers rather than police. That shift stems from the rollout of a program known as Support Team Assisted Response, or STAR, which sends a mental health clinician and paramedic to respond to certain 911 calls about nonviolent behavior.

The program, and others like it, aim to defuse the tensions that can arise when police officers confront civilians in distress. Critics of these experimental programs have suggested that such reduced police involvement could allow crime to flourish. Now, researchers have found that during its pilot phase, the STAR program did not appear to lead to more violent crime. And reports of minor crimes substantially decreased, the researchers conclude June 8 in Science Advances.
Much of that reduction occurred because the health responders do not issue citations or make arrests (SN: 12/18/21). But even that reduction in reported crime is beneficial, says economist Thomas Dee of Stanford University. “That person is getting health care instead of being arrested.”

Following the death of George Floyd at the hands of a white police officer and the subsequent rise of the Black Lives Matter movement in the summer of 2020, cities throughout the country have been rolling out programs like STAR. “We cannot police our way out of every social problem,” says Temitope Oriola, a sociologist at the University of Alberta in Edmonton, Canada. But so far there have been few studies of these programs’ effects on crime, let alone on the reduction of violence between police and the public (SN: 7/9/20).

Dee and Jayme Pyne, a sociologist also at Stanford, looked at the STAR program’s impact on crime reports. The duo investigated the program’s pilot phase, which ran from June to November 2020 and encompassed eight of the city’s 36 police precincts. Police officers and 911 operators in those eight precincts redirected calls for minor and non-dangerous complaints to STAR providers. These calls included concerns about trespassing, indecent exposure, intoxication and similar low-level offenses. During the six-month pilot, STAR providers responded to 748 calls, averaging roughly six incidents per eight-hour shift.

Dee and Pyne analyzed criminal offenses in all 36 precincts from December 2019 to November 2020. They then compared the change in crime rates in the eight precincts receiving STAR services with the change in crime rates in the other 28 precincts. The rate of violent crime remained unchanged across the board, including in the precincts where the STAR program was active, the researchers found. But there was a 34 percent drop in reports of minor offenses in the STAR precincts, from an average of about 84 offenses per month in each district to an average of about 56 citations.

The data also suggest that the actual level of minor crimes and complaints dropped too — that is, the drop wasn’t just due to a lack of reporting, the researchers say. Prior to the pilot, minor offenses in the eight precincts receiving STAR services resulted in an average of 1.4 citations per incident. So having health care workers rather than police respond to 748 such calls should generate roughly 1,000 fewer citations, the authors calculate. Instead, citations dropped by almost 1,400. Providing people in crisis with access to health services may be preventing them from reoffending, Dee says.

Research into these sorts of programs is crucial, says Michael Vermeer, a justice policy researcher with the RAND Corporation, a public policy research organization headquartered in Santa Monica, Calif. But he cautions against drawing firm conclusions from a single study launched at the onset of the COVID-19 crisis, which dramatically changed crime rates and patterns across the country. “They just got confounded by the pandemic,” Vermeer says.

Dee agrees that he and other researchers now need to replicate this study across more cities, and also scale up in Denver. The city has since expanded the STAR program beyond the initial pilot.

Even if researchers eventually find that STAR and similar programs don’t budge crime rates much, that doesn’t mean that the programs are unsuccessful, says sociologist Brenden Beck of the University of Colorado Denver. He points to the potential to save taxpayer dollars. Dee and Pyne estimate that a single offense processed through STAR costs about $150, compared with the roughly $600 it costs to process one through the criminal justice system.

What’s more, helping people having nonviolent mental health crises get help and stay out of jail lets these individuals hold onto their jobs and stay present in their family members’ lives, Beck says. “I would hope we as a research community move on to study the benefit of these programs not just in terms of crime but also in terms of human welfare.”