Not long before the end of the school year, my husband and I received an e-mail from our fifth-grader’s principal that may now be all-too-familiar to many parents. The subject line included the words, “MULTIPLE COVID CASES.” 

Several students in my daughter’s class had tested positive for COVID-19. Her school acted fast. It reinstated a mask mandate for 10 days and required students not up-to-date on their COVID-19 vaccinations to quarantine.

These precautions may have helped — my daughter didn’t end up bringing the virus home. But for kids who do, COVID-19 can hopscotch through households, knocking down relatives one by one. And it’s not clear how long one infection protects you from a second round with the virus.

Recent high-profile cases have put reinfections in the spotlight. Health and Human Services Secretary Xavier Becerra has had two bouts of COVID-19 in less than a month. So has The Late Show host Stephen Colbert. Back at his desk in May, he joked, “You know what they say. ‘Give me COVID once, shame on you. Give me COVID twice, please stop giving me COVID.’”

Just a few months ago, scientists thought reinfections were relatively rare, occurring most often in unvaccinated people (SN: 2/24/22). But there are signs the number may be ticking up. 

An ABC News investigation that contacted health departments in every state reported June 8 that more people seem to be getting the virus again. And omicron, the variant that sparked last winter’s surge, is still spawning sneaky subvariants. Some can evade antibodies produced after infection with the original omicron strain, scientists report June 17 in Nature. That means a prior COVID-19 infection might not be as helpful against future infections as it once was (SN:8/19/21). What’s more, reinfection could even add to a person’s risk of hospitalization or other adverse outcomes, a preliminary study suggests.

Scientists are still working to pin down the rate of reinfection. Like most questions involving COVID-19 case numbers, the answer is more than a little murky. “You really need to have a cohort of people who are well followed and tested every time they have symptoms,” says Caroline Quach-Thanh, an infectious diseases specialist at CHU Sainte-Justine, a pediatric hospital at the University of Montreal. 

A recent look at hundreds of thousands of COVID-19 cases among people in the province of Quebec found that roughly 4 percent were reinfections, scientists report in a preliminary study posted May 3 at medRxiv.org (SN:5/27/22). Quach-Thanh has seen an even smaller rate in her own study of health care workers first infected between March and September of 2020. Those data are still unpublished, but she points out that most of the people in her study were vaccinated. “A natural infection with three doses of vaccines protects better than just a natural infection,” she says. 

As many families, mine included, gear up for summer camps and vacations, I wanted to learn more about our current COVID-19 risks. I chatted with Quach-Thanh and Anna Durbin, an infectious diseases physician at Johns Hopkins Bloomberg School of Public Health who has studied COVID-19 vaccines. Our conversations have been edited for length and clarity.

What’s the latest on reinfections? Is the picture changing?

Durbin: We have to remember that the virus strain that’s circulating now is very different from the earlier strains. Whether you’ve been infected with COVID-19 or vaccinated, your body makes an immune response to fight future infections. It recognizes [the strain] your body originally saw. But as the virus changes, as it did with omicron, it becomes sort of a fuzzier picture for the immune system. It’s not recognizing the virus as well, and that’s why we’re seeing reinfections. 

I’ll also say that reinfections — particularly with respiratory viruses — are very common.

How can scientists distinguish a true reinfection from a relapse of an original infection?

Quach-Thanh: There are multiple ways of looking at this. The first is looking at the time elapsed between the first infection and a new positive PCR test. If it has been more than three months, it is unlikely to be just a remnant of a previous infection. We can also look at viral load. A really high viral load usually means it’s a new infection. But the best way to tell is to sequence the virus [to determine its genetic makeup] to see if it is actually a new strain. 

What do we know about the health risks of reinfection?

Quach-Thanh: The good thing is that most of the people who got reinfected [in the Quebec study] got a mild disease, and the risk of hospitalization and death was much lower. 

When you get reinfected, you might [have symptoms] like a cold, or even sometimes a cough, and a little bit of a fever, but you usually don’t progress to complications as much as you would with your first infection — if you’re vaccinated.

Does reinfection increase your chance of developing long COVID?

Durbin: I think that’s unknown, but it’s being studied. 

As we look back at the omicron wave in the U.S. that happened in January and February, now is about the time we would start to see symptoms of long COVID. So far it looks promising. We seem to be seeing a lower incidence of long COVID [after reinfection with omicron] than we did with primary infection, but those data are going to continue to be collected over the next few months.

At this point in the pandemic, how cautious do we need to be?

Quach-Thanh: It depends on your baseline risk of complications. If you’re healthy, if you’re doing most activities outdoors, if you’re vaccinated, life can proceed. But if you’re immune suppressed or elderly, the situation might be different.

If you have symptoms, it would be advisable to not mingle in indoor settings without a mask so that you don’t contaminate other people. There are immunocompromised people who might be at risk of serious infection. We still need to keep them in mind. I think we have to be responsible, and if we’re sick, we should get tested.

Durbin: This is what I tell my friends, family and patients: This virus is here to stay. Any time you’re in a crowded place with poor ventilation and lots of people, there’s a chance there’s going to be transmission. The risk is never going to be zero. It’s a message people don’t want to hear. But as long as there are people to infect, this virus is not going away. 

We have to move to acceptance, and we have to be better members of society. If we can, we should stay home when we’re sick. If we can’t stay home, we should wear a mask. We should wash our hands regularly. These are things that work to reduce transmission.

They reduce your risk of getting not just COVID-19, but also a cold or the flu.

Can we anticipate another surge in cases?

Quach-Thanh: I think the next wave will come in the fall. The problem with this virus is that it mutates. And as long as it’s transmitted, it will continue to mutate.

What can we look forward to? 

Durbin: I think young kids getting vaccinated is going to reduce the ability of the virus to spread (SN: 6/17/22). That’s good news.

In the 1920s, laborers and amateur archaeologists at gravel quarry pits in southeastern England uncovered more than 300 ancient, sharp-edged oval tools. Researchers have long suspected that these hand axes were made 500,000 to 700,000 years ago. A new study confirms that suspicion in the first systematic excavation of the site, known as Fordwich.

Dating those tools and more recent finds suggests that humanlike folk inhabited the area between about 560,000 and 620,000 years ago, researchers report in the June Royal Society Open Science. Relatively warm conditions at that time drew hominids to what’s now northern Europe before the evolutionary rise of Neandertals and Homo sapiens.

The results confirm that Fordwich is one of the oldest hominid sites in England. Previous discoveries place hominids in what’s now southeastern England at least 840,000 years ago (SN: 7/7/10) and perhaps as far back as nearly 1 million years ago (SN: 2/11/14). No hominid fossils have been found at Fordwich. It’s unclear which species of the human genus made the tools.

In 2020, archaeologist Alastair Key of the University of Cambridge and colleagues unearthed 238 stone artifacts at Fordwich that display grooves created by striking the surface with another stone. Other finds include three stones with resharpened edges, presumably used to scrape objects like animal hides.

A method for determining when sediment layers were last exposed to sunlight indicated that the newly discovered artifacts date to roughly 542,000 years ago. The previously unearthed hand axes probably came from the same sediment.

Hominids must have fashioned tools at Fordwich a bit earlier than 542,000 years ago because ancient climate data suggest that an ice age at that time made it hard to survive in northern Europe, the team concludes. Warmer conditions between 560,000 and 620,000 years ago would have enabled the hominid toolmakers to live so far north.

Monkeypox is not yet a global public health emergency, the World Health Organization said June 25.

The decision comes as the outbreak of the disease related to smallpox continues to spread, affecting at least 4,100 people in 46 countries as of June 24. That includes at least 201 cases in the United States. Those cases have been found in 25 states and the District of Columbia, according to the U.S. Centers for Disease Control and Prevention.

“Controlling the further spread of outbreak requires intense response efforts,” and the situation should be reevaluated in a few weeks, the WHO committee evaluating the outbreak said in an announcement.

The declaration of a public health emergency would have potentially made it easier to get treatments and vaccines to people infected with or exposed to the virus. Some medications and vaccines that could help fend off monkeypox are approved for use against smallpox, and can be used against monkeypox only with special authorization.

The virus that causes monkeypox, named for its discovery in monkeys in 1958 though it is probably a virus that mainly infects rodents, is not a new threat. Countries in central Africa, where monkeypox is endemic, have had sporadic outbreaks since researchers found the first human case in 1970. Places in western Africa had few cases until 2017. But most cases outside the continent were travel-related, with limited spread to others (SN: 5/26/22). 

“Monkeypox has been circulating in a number of African countries for decades and has been neglected in terms of research, attention and funding,” WHO director-general Tedros Ghebreyesus said in a statement announcing the decision. “This must change not just for monkeypox but for other neglected diseases in low-income countries as the world is reminded yet again that health is an interconnected proposition.”

Monkeypox typically kills fewer than 10 percent of people who contract it. At least one person has died in the global outbreak.  

As case numbers climb, researchers are working to decipher the genetic blueprint of the virus, in hopes of uncovering whether some viral mutations might explain why the virus has quickly gained a foothold in new places. 

Tracing the mutations

The closest known relative of the versions of the virus behind the global outbreak comes from Nigeria, hinting that the outbreak may have got its start there. 

In the newest surge in cases, scientists have uncovered more viral changes than anticipated — a sign that the virus may have been circulating undetected among people for a while, perhaps since Nigeria’s 2017–2018 monkeypox outbreak, new research suggests. What’s more, a group of enzymes known for their virus-fighting abilities in the body may be to blame for many of those mutations. 

A genetic analysis of monkeypox viruses involved in the global outbreak from 15 people across seven countries shows that these viruses have an average of 50 more genetic tweaks than versions circulating in 2018 and 2019, researchers report June 24 in Nature Medicine. That’s roughly six to 12 times as many mutations as scientists would have expected the virus to develop over that time. Unlike some other types of viruses, poxviruses, which include smallpox and monkeypox viruses, typically mutate fairly slowly.  

The changes have a pattern that is a hallmark of an enzyme family called APOBEC3, the researchers say. These enzymes edit DNA’s building blocks — represented by the letters G, C, A and T — in a specific way: Gs change to As and Cs to Ts. The analysis found that particular pattern in the viral sequences, suggesting that APOBEC3s are responsible for the mutations. 

Ideally, so many DNA building blocks are swapped for another that a virus is effectively destroyed and can’t infect more cells. But, sometimes, APOBEC3 enzymes don’t make enough changes to knock out the virus. Such mutated, though still functional, viruses can go on to infect additional cells, and possibly another person. 

A big question, though, is whether the genetic tweaks seen in the monkeypox virus are helpful, harmful or have no effect at all on the virus. 

While it’s still unknown whether the enzymes are directly responsible for the changes in the monkeypox virus, similar mutations are still popping up, the team found. So, APOBEC3s may still be helping the virus change as it continues to spread. One member of the enzyme family is found in skin cells, where people with monkeypox can develop infectious pox lesions.         

Different symptoms

Symptoms reported in the global outbreak have been generally milder than those reported in previous outbreaks, perhaps allowing the disease to spread before a person knows they’re infected. 

It is not clear whether those differences in symptoms are related to changes in the virus, Inger Damon, director of the CDC’s Division of High-Consequence Pathogens and Pathology, said June 21 in a news briefing hosted by SciLine, a service for journalists and scientists sponsored by the American Association for the Advancement of Science. 

Typically, in previous outbreaks, people would develop flu-like symptoms, including fever, headaches, muscle aches and exhaustion about a week or two after exposure to the virus. Then, one to three days after those symptoms start, a rash including large pus-filled lesions pops up generally starting on the face and limbs, particularly the hands, and spreads over the body. Though generally milder, those symptoms are similar to smallpox, but people with monkeypox also tend to develop swollen lymph nodes. 

All patients in the U.S. outbreak have gotten rashes, Damon said, “but the lesions have been scattered or localized to a specific body site, rather than diffuse, and have not generally involved the face or the … palms of the hand or the soles of the feet.” Instead, rashes may start in the genital or anal area where they can be mistaken for sexually transmitted diseases, such as syphilis or herpes, she said. 

In many cases, the rashes have not spread to other parts of the body. And the classical early symptoms such as fever have been “mild and sometimes nonexistent before a rash appears,” Damon said. 

Monkeypox is transmitted from person to person through close skin-to-skin contact or by contact with contaminated towels, clothes or bedding. It may also be spread by droplets of saliva exchanged during kissing or other intimate contact. The CDC is investigating whether the virus might be spread by semen as well as skin-to-skin contact during sex, Agam Rao, a captain in the U.S. Public Health Service, said June 23 at a meeting of the CDC’s Advisory Committee on Immunization Practices.

“We don’t have any reason to suspect it is spread any other way,” such as through the air, Rao said.

In Nigeria, more monkeypox cases have been recorded among women, while the global outbreak has affected mainly men, particularly men who have sex with men. Experts warn that anyone can be infected with monkeypox, and some people face an increased risk of severe disease. Those at increased risk include children, people who are immunocompromised, pregnant people and people with eczema. 

The risk of catching monkeypox through casual contact is still low in the United States, Rao said. But data she presented show that while people in the country have contracted monkeypox while traveling abroad, cases have also spread locally.

On June 24, the U.S. Supreme Court overturned Roe v. Wade. By undoing the landmark 1973 decision that protected a person’s right to an abortion, the highest court in the country has shifted decisions about this medical care to individual state and local governments.

Some states have already passed laws that curtail abortion access. Now, without the federal protections Roe v. Wade provided, other states will likely follow suit.

Many of those legislative efforts invoke medical and scientific language, in an effort to define when life begins. Heart development, fetal pain and viability have all been brought into justification for abortion restrictions. But many of these rationales don’t line up with the biology of early development. Texas’ 2021 “heartbeat law,” for instance, bans abortion after about six weeks when heart cells purportedly begin thumping. At that early stage of pregnancy, there isn’t yet a fully formed heart to beat. 

Like most aspects of biology, early human development involves many complex processes.  Despite the rhetoric around these issues, clear lines — between having a heart and not having a heart or being able to survive outside of the uterus — are scarce, or nonexistent.

“There aren’t these set black-and-white points for much of this,” says obstetrician-gynecologist Nisha Verma, a fellow with the American College of Obstetricians and Gynecologists in Washington, D.C.

Here’s what’s known about five key aspects of pregnancy biology that often come up in abortion debates.

1. The early timeline of a pregnancy is easy to misunderstand.

That’s because how dates are determined is supremely confusing. The standard pregnancy clock actually starts ticking before a sperm cell encounters an egg, two weeks before, on average. An ovary releases an egg around day 14 of an average 28-day menstrual cycle (SN: 6/19/21) . (Day 1 is the first day of menstruation; day 1 is also when a pregnancy officially begins in the month an egg is fertilized.) That means that when a sperm fertilizes an egg, a person is already officially two weeks pregnant. As nonsensical as that sounds, it’s the simplest way medical professionals can date a pregnancy.

That timeline means that abortion bans at six weeks, enacted in Texas, Oklahoma and Idaho, take effect earlier in pregnancy than many people think, Verma says. In 2020, she surveyed people in Georgia, where she was practicing medicine at the time, about their understanding of the timing. “Some people will say the six weeks is after your first missed period,” she says. “Some people think it’s from the date of conception.” Neither is correct.

The ban would start four weeks after fertilization. Counting back, that’s two weeks after a missed period, which is often a person’s first indication that they might be pregnant. Such bans leave a person very little time — two weeks after a missed period — to access an abortion.

What’s more, these dates are based on averages. Many women have irregular menstrual cycles. Birth control isn’t 100 percent effective, and certain types can eliminate menstruation altogether, throwing even more uncertainty into the early timeline of pregnancy.

By the numbers

Most abortions in the United States happen very early in pregnancy, data collected in 2019 by the U.S. Centers for Disease Control and Prevention show. Fewer than 5 percent of abortions are done at or after week 16 of pregnancy.  

U.S. abortions in 2019 by week of pregnancy

Source: CDC

2. Pregnancy takes more than sperm meeting egg.

That meeting, which usually takes place in one of the two fallopian tubes near the ovaries, is fertilization, a process in which two cells fuse and mingle their genetic contents, creating what’s known as a zygote (SN: 1/10/15). But a fertilized egg does not automatically lead to a pregnancy, says obstetrician and gynecologist Jonas Swartz of Duke University School of Medicine. “Equating them doesn’t make sense from a medical standpoint.” Up to 50 percent of fertilized eggs do not implant in the uterus, researchers have estimated.

The genetic material needs to combine in the right way. The growing ball of cells needs to travel to the uterus and implant itself in the right spot. And the right balance of hormones need to be churned out to support the pregnancy. “There are so many things other than the sperm meeting the egg that actually matter for this to become a pregnancy that has a chance to develop further,” says Selina Sandoval, an obstetrician and gynecologist who specializes in complex family planning at the University of California, San Diego.

Lawmakers in some states are considering abortion rules that apply to a fertilized egg; Oklahoma had already passed such a law. That includes fertilized eggs that lodge in the wrong spot, the fallopian tube, for example. Called an ectopic pregnancy, this can lead to life-threatening medical emergencies when the growing tissue ruptures the tube and internal bleeding ensues. “These are pregnancies that under no circumstance can become a healthy pregnancy,” Sandoval says. “In fact, if they aren’t treated and continue to grow, they will kill the patient.” Laws that apply to a fertilized egg could “limit our ability to treat patients for ectopic pregnancies,” she says.

3. “Heartbeat laws” are not what they seem.

A Texas law bans abortions “after detection of an unborn child’s heartbeat.” But the rhythmic sounds heard on an ultrasound early in pregnancy aren’t caused by the opening and closing of heart valves as they move blood through the heart’s chambers, the motion that produces a typical lub dub sound. That’s because those chambers haven’t yet developed. On early ultrasounds, the heartbeat-like sounds are created by the ultrasound machine itself.

“What we’re seeing is actually the primitive heart tube and the cells in that heart tube having electrical activity that causes fluttering,” Verma says. “The ultrasound is actually manufacturing that sound based on the electrical activity and fluttering motion.”

Using the term “heartbeat” to describe the fluttering makes sense in some situations, like in conversations with excited parents-to-be, Verma says. “I’ve taken care of countless people who have seen that first ‘heartbeat’ on ultrasound for a desired pregnancy, and it’s this huge, exciting moment,” she says. “I don’t want to be dismissive of that.” She says two things can be true at the same time: “It can be exciting for a patient. It also isn’t a scientific thing.”

4. Fetal pain is difficult to define.

A bit of biology that’s often used to restrict abortions is the claim that fetuses (which form at week 11 of pregnancy) feel pain.

“Pain is very complex,” Swartz says. “It requires not just a physical response, but the ability to suffer as a result.”

Knowing what a fetus experiences is impossible, but brain development studies provide some clues. The experience of pain starts with the senses detecting something noxious. Those signals then have to travel to the cortex, the outer layer of the brain that helps interpret that sensation. In human fetuses, those brain connections don’t exist until about week 24 or 25 of pregnancy. In guidelines written by members of the Society for Maternal-Fetal Medicine, researchers write that these connections are necessary for the experience of pain, but are not sufficient on their own to conclude that pain is possible.

In human fetuses, these connections aren’t actually operational until about week 28 or 29 of pregnancy, other studies suggest. “We can say with really, really good confidence that no sooner than 28 weeks is [pain] even possible,” Sandoval says. 

The vast majority of abortions — over 90 percent — happen in the first trimester, before week 13 of pregnancy. The number of abortions after 24 or 25 weeks is “vanishingly small,” Swartz says.

5. When a fetus could survive on its own is a complex medical calculation.

The word “viability” is often used as a sharp cut-off point to mark the age at which a fetus could survive outside of the uterus. The problem is that one clear cut-off does not exist.

“That has been a moving line as science has advanced and our ability to support very small babies has advanced,” Swartz says. “But it’s also not a fixed line for babies born now.”  

On average, babies born around 22 to 24 weeks gestation either don’t survive or they survive with major health problems. Whether a fetus will survive if delivered depends on a whole suite of other factors, Swartz says. They include fetal sex, weight, developmental issues and mother’s health, not to mention individual health care facilities’ capabilities and training.

The American College of Obstetricians and Gynecologists recently removed mentions of “viability” in their guidance on abortion care. “It’s such a complicated concept that we can’t make blanket statements about it,” Verma says. “It’s something that needs to be left to the clinician looking at the patient.”

Inaccurate descriptions of biology can influence restrictions around reproductive health, and as a result, the health care people are able to receive, Swartz says. A colleague of his, for instance, wasn’t able to get appropriate medical care when she experienced signs of a pregnancy loss. Because of state abortion restrictions, her physician decided to delay treatment, an emotionally distressing experience she wrote about last year in Obstetrics and Gynecology. Abortion regulations based on flawed medical and scientific premises, Swartz says, “places priority on a potential life over the actual life of the person sitting in front of me.”

Does the eel use electric fields to navigate? — Science News, June 24, 1972

Many species of ocean fish [such as American eels] migrate over large distances. Some of them do so with such extreme accuracy that they can come thousands of miles to return to the stream or area where they were born. Naturalists naturally wonder how they do it. One of the suggestions is that they use electricity.

Update

It’s still a mystery how the American eel (Anguilla rostrata) navigates to its breeding grounds. But a growing body of evidence has shifted focus from electricity to magnetic fields. Experiments suggest that the American eel’s European cousin, A. anguilla, seems to follow a magnetic map to the North Atlantic’s Sargasso Sea, guided by an internal compass (SN Online: 4/13/17). In March, scientists proposed that freshly spawned A­merican and European eels follow paths of increasing magnetic intensity from the Sargasso Sea to their freshwater homes. As adults, the eels may sense decreasing intensity to retrace the path to their birthplace.

Bits of charcoal entombed in ancient rocks unearthed in Wales and Poland push back the earliest evidence for wildfires to around 430 million years ago. Besides breaking the previous record by about 10 million years, the finds help pin down how much oxygen was in Earth’s atmosphere at the time.

The ancient atmosphere must have contained at least 16 percent oxygen, researchers report June 13 in Geology. That conclusion is based on modern-day lab tests that show how much oxygen it takes for a wildfire to take hold and spread.

While oxygen makes up 21 percent of our air today, over the last 600 million years or so, oxygen levels in Earth’s atmosphere have fluctuated between 13 percent and 30 percent (SN: 12/13/05). Long-term models simulating past oxygen concentrations are based on processes such as the burial of coal swamps, mountain building, erosion and the chemical changes associated with them. But those models, some of which predict lower oxygen levels as low as 10 percent for this time period, provide broad-brush strokes of trends and may not capture brief spikes and dips, say Ian Glasspool and Robert Gastaldo, both paleobotanists at Colby College in Waterville, Maine.

Charcoal, a remnant of wildfire, is physical evidence that provides, at the least, a minimum threshold for oxygen concentrations. That’s because oxygen is one of three ingredients needed to create a wildfire. The second, ignition, came from lightning in the ancient world, says Glasspool. The third, fuel, came from burgeoning plants and fungus 430 million years ago, during the Silurian Period. The predominant greenery were low-growing plants just a couple of centimeters tall. Scattered among this diminutive ground cover were occasional knee-high to waist-high plants and Prototaxites fungi that towered up to nine meters tall. Before this time, most plants were single-celled and lived in the seas.

Once plants left the ocean and began to thrive, wildfire followed. “Almost as soon as we have evidence of plants on land, we have evidence of wildfire,” says Glasspool.

That evidence includes tiny chunks of partially charred plants — including charcoal as identified by its microstructure — as well as conglomerations of charcoal and associated minerals embedded within fossilized hunks of Prototaxites fungi. Those samples came from rocks of known ages that formed from sediments dumped just offshore of ancient landmasses. This wildfire debris was carried offshore in streams or rivers before it settled, accumulated and was preserved, the researchers suggest.

The discovery adds to previous evidence, including analyses of pockets of fluid trapped in halite minerals formed during the Silurian, that suggests that atmospheric oxygen during that time approached or even exceeded the 21 percent concentration seen today, the pair note.

“The team has good evidence for charring,” says Lee Kump, a biogeochemist at Penn State who wasn’t involved in the new study. Although its evidence points to higher oxygen levels than some models suggest for that time, it’s possible that oxygen was a substantial component of the atmosphere even earlier than the Silurian, he says.

“We can’t rule out that oxygen levels weren’t higher even further back,” says Kump. “It could be that plants from that era weren’t amenable to leaving a charcoal record.”

There’s a new record holder for biggest bacterium — and you don’t need a microscope to see it.

The newfound species, Thiomargarita magnifica, is roughly a centimeter long, and its cells are surprisingly complex, researchers report in the June 24 Science.

The bacterial behemoth is roughly the size and shape of a human eyelash, marine biologist Jean-Marie Volland of the Laboratory for Research in Complex Systems in Menlo Park, Calif., said June 21 at a news conference. Maxing out at approximately 2 centimeters, T. magnifica is about 50 times the size of other giant bacteria and about 5,000 times the size of most other average-size bacterial species.

What’s more, while the genetic material of most bacteria floats freely inside the cell, T. magnifica packs its DNA inside a sac surrounded by a membrane (SN: 6/22/17). Such a compartment is a hallmark of the larger, more complex cells of eukaryotes, a group of organisms that includes plants and animals.

Study coauthor Oliver Gros, a marine biologist at the Université des Antilles Pointe-á-Pitre in Guadeloupe, France, first discovered T. magnifica while collecting water samples in tropical marine mangrove forests in the Caribbean’s Lesser Antilles. At first, he mistook the long, white filaments as some sort of eukaryote, Gros said at the news conference. But a few years later, genetic analyses showed that the organisms were actually bacteria. A closer look under the microscope revealed the cells’ DNA-containing sacs.

Previous studies had predicted that bacterial cells’ overall lack of complexity meant there was a limit to how large bacteria could grow. But the new discovery is “breaking our way of thinking about bacteria,” says Ferran Garcia-Pichel, a microbiologist at Arizona State University in Tempe who was not involved with the study. When it comes to bacteria, people typically think small and simple. But that mindset may make researchers miss lots of other bacterial species, Garcia-Pichel says. It’s a bit like thinking the largest animal that exists is a small frog but then scientists discover elephants.

It’s still unclear what role T. magnifica plays among the mangroves. Also unknown is why it evolved to be so large. One possibility, Volland said, is that being centimeters long helps cells access both oxygen and sulfide, which the bacteria need to survive.

Despite the scary name, modern vampire squid are docile denizens of the deep sea — but their Jurassic ancestors may have been a lot fiercer.

Analyses of fossilized soft tissue from three 164-million-year-old specimens of Vampyronassa rhodanica suggest that the ancient cephalopods had some powerful weapons, researchers say June 23 in Scientific Reports. Unlike its blobby modern relative, V. rhodanica had a more streamlined muscular body, with two of its eight arms twice as long as the other six. Strong suckers on all eight arms could have helped it snatch and hold onto prey.

Modern vampire squid (Vampyroteuthis infernalis) are not actually squid; they’re the only surviving members of an ancient, diverse order of cephalopods, the Vampyromorpha. And V. infernalis are pretty passive about finding food (SN: 6/25/12). Alongside their arms, they have two long, retractable, sticky filaments that they use like flypaper to collect ”marine snow,” tiny bits of dead plankton or sinking fecal pellets that happen to drift past (SN: 5/19/15).

Fossilized tissue suggests V. rhodanica had a very different lifestyle, report paleontologist Alison Rowe of Sorbonne University in Paris and her colleagues.

Both the ancient and the modern creatures have eight arms bearing suckers flanked by hairlike cirri. But the ancient cephalopod’s suckers are attached to the arms by stalks embedded in round layers of muscle. That muscular arrangement, the team says, would have greatly increased the pressure differential inside the sucker — making its suction more powerful. The creature’s numerous, closely packed cirri may have helped it sense prey, similar to a strategy used by some modern octopuses.

V. infernalis’ suckers, lacking that muscle arrangement, don’t have such a strong grip. Instead, its suckers secrete mucus that coats whatever the creatures have captured with their filaments. The cirri then slide that slippery food along the arms and into its mouth.

For many cats, a mere whiff of catnip can send them into a licking, rolling, plant-shredding frenzy.

That destruction amplifies catnip’s natural defenses against insects and its appeal to cats, a new chemical analysis finds. Compared with intact leaves, crushed-up leaves emit more volatile compounds called iridoids, which act as an insect repellant, researchers report June 14 in iScience. The higher emissions also seem to encourage cats to continue rolling around in the remains of the plant, effectively coating themselves in a natural bug spray (SN: 3/4/21).

Masao Miyazaki, a biologist at Iwate University in Morioka, Japan, and his colleagues analyzed the chemistry of both catnip (Nepeta cataria) and silver vine (Actinidia polygama), a plant common in Asia that has a similar euphoric effect on cats. Both plants naturally produce iridoids, which discourage insects from snacking on leaves.

As cats toyed with silver vine, the damaged leaves released about 10 times more iridoids than intact leaves did, and also changed the proportion of the chemicals released. The researchers also found that catnip when crushed up released over 20 times more of its insect repellant, mostly a type of iridoid called nepetalactone.

With both plants, lab-made iridoid cocktails mimicking those of damaged catnip and silver vine chased off more mosquitoes than chemical solutions that mirrored those of intact leaves, the study found.

The team also presented cats with two dishes — one with intact silver vine and one with damaged leaves. Without fail, the cats would go to the damaged leaf container and lick and play with the dish and roll against it.

PASADENA, Calif. — A lucky celestial alignment has given astronomers a rare look at a galaxy in the early universe that is seeding its surroundings with the elements needed to forge subsequent generations of stars and galaxies.

Seen as it was just 700 million years after the Big Bang, the distant galaxy has gas flowing over its edges. It is the earliest-known run-of-the-mill galaxy, one that could have grown into something like the Milky Way, to show such complex behavior, astronomer Hollis Akins said June 14 during a news conference at the American Astronomical Society meeting.

“These results also tell us that this outflow activity seems to be able to shape galaxy evolution, even in this very early part of the universe,” said Akins, an incoming graduate student at the University of Texas at Austin. He and colleagues also submitted their findings June 14 to arXiv.org.

The galaxy, called A1689-zD1,­ shows up in light magnified by Abell 1689, a large galaxy cluster that can bend and intensify, or gravitationally lens, light from the universe’s earliest galaxies (SN: 2/13/08; SN: 10/6/15). Compared with other observed galaxies in the early universe, A1689-zD1 doesn’t make a lot of stars — only about 30 suns each year — meaning the galaxy isn’t very bright to our telescopes. But the intervening cluster magnified A1689-zD1’s light by nearly 10 times.

Akins and colleagues studied the lensed light with the Atacama Large Millimeter/submillimeter Array, or ALMA, a large network of radio telescopes in Chile. The team mapped the intensities of a specific spectral line of oxygen, a tracer for hot ionized gas, and a spectral line of carbon, a tracer for cold neutral gas. Hot gas shows up where the bright stars are, but the cold gas extends four times as far, which the team did not expect.

“There has to be some mechanism [to get] carbon out into the circumgalactic medium,” the space outside of the galaxy, Akins says.

Only a few scenarios could explain that outflowing gas. Perhaps small galaxies are merging with A1689-zD1 and flinging gas farther out where it cools, Akins said. Or maybe the heat from star formation is pushing the gas out. The latter would be a surprise considering the relatively low rate of star formation in this galaxy. While astronomers have seen outflowing gas in other early-universe galaxies, those galaxies are bustling with activity, including converting thousands of solar masses of gas into stars per year.

The researchers again used the ALMA data to measure the motions of both the cold neutral and hot ionized gas. The hot gas showed a larger overall movement than the cold gas, which implies it’s being pushed from A1689-zD1’s center to its outer regions, Akins said at the news conference.

Despite the galaxy’s relatively low rate of star formation, Akins and his colleagues still think the 30-solar-masses of stars a year heat the gas enough to push it out from the center of the galaxy. The observations suggest a more orderly bulk flow of gas, which implies outflows, however the researchers are analyzing the movement of the gas in more detail and cannot yet rule out alternate scenarios.

They think when the hot gas flows out, it expands and eventually cools, Akins said, which is why they see the colder gas flowing over the galaxy’s edge. That heavy-element-rich gas enriches the circumgalactic medium and will eventually be incorporated into later generations of stars (SN: 6/17/15). Due to gravity’s pull, cool gas, often with fewer heavy elements, around the galaxy also falls toward its center so A1689-zD1 can continue making stars.

These observations of A1689-zD1 show this flow of gas happens not only in the superbright, extreme galaxies, but even in normal ones in the early universe. “Knowing how this cycle is working helps us to understand how these galaxies are forming stars, and how they grow,” says Caltech astrophysicist Andreas Faisst, who was not involved in the study.

Astronomers aren’t done learning about A1689-zD1, either. “It’s a great target for follow-up observations,” Faisst says. Several of Akins’s colleagues plan to do just that with the James Webb Space Telescope (SN: 10/6/21).

Physicists have found the strongest sign yet of a fabled four of a kind.

For six decades, researchers have hunted for clusters of four neutrons called tetraneutrons. But evidence for their existence has been shaky. Now, scientists say they have observed neutron clusters that appear to be tetraneutrons. The result strengthens the case that the fab four is more than a figment of physicists’ imaginations. But some scientists doubt that the claimed tetraneutrons are really what they seem.

Unlike an atomic nucleus, in which protons and neutrons are solidly bound together, the purported tetraneutrons seem to be quasi-bound, or resonant, states. That means that the clumps last only for fleeting instants — in this case, less than a billionth of a trillionth of a second, the researchers report in the June 23 Nature.

Tetraneutrons fascinate physicists because, if confirmed, the clusters would help scientists isolate and probe mysterious neutron-neutron forces and the inner workings of atomic nuclei. All atomic nuclei contain one or more protons, so scientists don’t have a complete understanding of the forces at play within groups composed only of neutrons.

Conclusively spotting the four-neutron assemblage would be a first. “Up to now, there was no real observation of … such a system that is composed only from neutrons,” says nuclear physicist Meytal Duer of the Technical University of Darmstadt in Germany.

To create the neutron quartets, Duer and colleagues started with a beam of a radioactive, neutron-rich type of helium called helium-8, created at RIKEN in Wako, Japan. The team then slammed that beam into a target containing protons. When a helium-8 nucleus and proton collided, the proton knocked out a group of two protons and two neutrons, also known as an alpha particle. Because each initial helium-8 nucleus had two protons and six neutrons, that left four neutrons alone.

By measuring the momenta of the alpha particle and the ricocheting proton, the researchers determined the energy of the four neutrons. The measurement revealed a bump on a plot of the neutrons’ energy across multiple collisions — the signature of a resonance.

Particle smashup

Physicists collided a helium-8 nucleus with a target proton and measured the momenta of the ricocheting proton and an escaping alpha particle — a clump of two neutrons and two protons. Those measurements revealed signs that the four neutrons released in the smashup formed a long-sought cluster called a tetraneutron.

In the past, “there were indications, but it was never very clear” whether tetraneutrons existed, says nuclear physicist Marlène Assié of Laboratoire de Physique des 2 Infinis Irène Joliot-Curie in Orsay, France. In 2016, Assié and colleagues reported hints of only a few tetraneutrons (SN: 2/8/16). In the new study, the researchers report observing around 30 clusters. The bump on the new plot is much clearer, she says. “I have no doubts on this measurement.”

But theoretical calculations of what happens when four neutrons collide have raised skepticism as to whether a tetraneutron resonance can exist. If the forces between neutrons were strong enough to create a tetraneutron resonance, certain types of atomic nuclei should exist that are known not to, says theoretical nuclear physicist Natalia Timofeyuk of the University of Surrey in Guildford, England.

Because of that contradiction, she thinks that the researchers have not observed a true resonance, but another effect that is not yet understood. For example, she says, the bump could result from a “memory” that the neutrons retain of how they were arranged inside the helium-8 nucleus.

Other types of theoretical calculations are a closer match with the new results. “Indeed, theoretical results are very controversial, as they either predict a tetraneutron resonance in good agreement with the results presented in this paper, or they don’t predict any resonance at all,” says theoretical nuclear physicist Stefano Gandolfi of Los Alamos National Laboratory in New Mexico. Further calculations will be needed to understand the results of the experiment.

New experiments could help too. Because detecting neutrons, which have no electric charge, is more difficult than detecting charged particles, the researchers didn’t directly observe the four neutrons. In future experiments, Duer and colleagues hope to spot the neutrons and better pin down the tetraneutrons’ properties.

Future work may reveal once and for all whether tetraneutrons are the real deal.  

It sounds like the setup for a joke: If radio waves give you radar and sound gives you sonar, what do gravitational waves get you?

The answer might be “GRADAR” — gravitational wave “radar” — a potential future technology that could use reflections of gravitational waves to map the unseen universe, say researchers in a paper accepted to Physical Review Letters. By looking for these signals, scientists may be able to find dark matter or dim, exotic stars and learn about their deep insides.

Astronomers routinely use gravitational waves — traveling ripples in the fabric of space and time itself, first detected in 2015 — to watch cataclysmic events that are hard to study with light alone, such as the merging of two black holes (SN: 2/11/2016).

But physicists have also known about a seemingly useless property of gravitational waves: They can change course. Einstein’s theory of gravity says that spacetime gets warped by matter, and any wave passing through these distortions will change course. The upshot is that when something emits gravitational waves, part of the signal comes straight at Earth, but some might arrive later — like an echo — after taking longer paths that bend around a star or anything else heavy.

Scientists have always thought these later signals, called “gravitational glints,” should be too weak to detect. But physicists Craig Copi and Glenn Starkman of Case Western Reserve University in Cleveland, Ohio, took a leap: Working off Einstein’s theory, they calculated how strong the signal would be when waves scatter through the gravitational field inside a star itself.

“The shocking thing is that you seem to get a much larger result than you would have expected,” Copi says. “It’s something we’re still trying to understand, where that comes from — whether it’s believable, even, because it just seems too good to be true.”

If gravitational glints can be so strong, astronomers could possibly use them to trace the insides of stars, the team says. Researchers could even look for massive bodies in space that would otherwise be impossible to detect, like globs of dark matter or lone neutron stars on the other side of the observable universe.

“That would be a very exciting probe,” says Maya Fishbach, an astrophysicist at Northwestern University in Evanston, Ill., who was not involved in the study.

There are still reasons to be cautious, though. If this phenomenon stands up to more detailed scrutiny, Fishbach says, scientists would have to understand it better before they could use it — and that will probably be difficult.

“It’s a very hard calculation,” Copi says.

But similar challenges have been overcome before. “The whole story of gravitational wave detection has been like that,” Fishbach says. It was a struggle to do all the math needed to understand their measurements, she says, but now the field is taking off (SN: 1/21/21). “This is the time to really be creative with gravitational waves.”

By now, wheat planted late last year waves in fields across Ukraine. Spring crops of sunflowers and barley are turning swaths of dark earth into a fuzz of bright green. But with Russia’s war being waged in some of the most fertile regions of Ukraine, uncertainty looms over summer harvesting.

Ukrainian farmers braved a war zone to carry out close to 80 percent of spring planting, covering roughly 14 million hectares. Still, Russia’s invasion has raised fears that not only are this year’s crop yields in jeopardy, but also that Ukraine’s agricultural output could be diminished for years. At the root of this worry, in part, is how warfare impacts soil.

Ukraine is home to some of the most fertile soil in the world, making it a top global producer of cereals, such as wheat and maize, as well as seed oils like sunflower oil. The country’s exports feed millions of people from Europe and Africa to China and Southeast Asia.

With the war in its fourth month, the Food and Agriculture Organization of the United Nations estimates at least 20 percent of Ukraine’s crops planted in winter will remain unharvested or went unplanted. And despite farmers’ best efforts, many spring crops went unplanted. This summer’s winter wheat harvest could be cut approximately in half (a loss of about 2 million hectares) and sunflower products cut by a third.

With warfare able to degrade and contaminate soil for years, crop yields — and the people who depend on them — could suffer long after a cease-fire.

“In many ways, the welfare of the soil system in postwar nations is really intricately tied to the welfare of the people,” says soil scientist Asmeret Asefaw Berhe of University of California, Merced. “And in many ways, it’s going to dictate their long-term future, too.”

Super soil

A type of grassland soil called chernozem covers nearly two-thirds of agricultural lands in Ukraine. Meaning “black earth,” chernozem is a Ukrainian and Russian word that describes highly fertile soils distinguished by one to two meters of dark, rich organic matter. Over the last 10,000 years, it accumulated along the Eurasian steppes, slowly building up as a black bed atop fine, windblown sediments called loess, which coated the region as the glaciers retreated. At the same time in North America, grassland soils similar to chernozems called mollisols formed over the Great Plains, creating twin breadbaskets.

Chernozems are rich in elements that plants need to grow, such as nitrogen, potassium and calcium. Those nutrients come from organic matter and underlying loess. Chernozems also hit the sweet spot of clay content — just enough to help hold the soil together and cling onto nutrients but not so much that roots have a hard time penetrating the ground.

In their natural state, chernozems come preloaded with vitamins and minerals, like a super-smoothie of plant nutrition. “Plants growing in these soils are lucky,” Berhe says. “They’re growing in an environment that has everything they need to grow, with or without additional fertilizers or extra supplements.”

Bombing fields

There’s a term for what war does to soil: bombturbation. It’s grim wordplay on the natural process of bioturbation — earthworms and other animals stirring up soil. In this case, though, exploding bombs and artillery fire fling clods of dirt and dig craters. Joseph Hupy, a soil geomorphologist at Purdue University in West Lafayette, Ind., coined the term with coauthor Randall Schaetzl in 2006 while studying soils’ battlefield scars.

At France’s World War I battlefield at Verdun, Hupy dug meter-long trenches with a backhoe across bomb craters and in their vicinity, looking for signs of disturbance. He wanted to understand how the landscape recovered, with or without human help. He found decades-old chaos beneath the surface. His cross sections revealed rubble, chunks of limestone bedrock embedded in a slurry of sandy soil and organics. That chaos was reflected on the surface too: Where there were craters, water flow had changed, leading to different patterns of vegetation growth, Hupy and a colleague reported in 2012 in Geomorphology. Because of shifts in hydrology and a lack of human management, the landscape reverted from agriculture to forest. “It’s a completely new ecosystem,” he says.

Hupy noted similar changes at Vietnam’s Khe Sanh, which the United States heavily bombed in 1968. Aerial images of Ukrainian battle zones show pockmarked fields, reminiscent of the sites Hupy studied in Vietnam. Problems in Ukrainian soil may not be limited to the surface. Even if farmers smooth over the top of the soil, underground rubble can act like a barrier or sluice for water, which could make it harder to grow crops.

When there’s a highly compacted area beneath where the teeth of a plow can go, that impermeable layer of soil “can create standing water, and all other sorts of problems from an agricultural standpoint,” Hupy says.

Trouble with tanks

Bombs may leave some of the most obvious impacts, but they aren’t the only thing that can physically disturb soil. Soggy, thawing soils in Ukraine bogged down Russian tanks as if a metaphor of resistance: The land itself was fighting back. But what’s bad for invading tanks is also bad for the soil. When tanks roll over a field, their weight makes soil clump and stick together. Wet soil can compound the problem, exacerbating compaction. And chernozems are particularly vulnerable to compaction: With their thick layer of organic matter, they’re fluffy and light.

Compaction can temporarily cut crop yields by anywhere from 10 percent to nearly 60 percent because it makes it more difficult for roots to reach nutrients and prevents water and fertilizers from penetrating the soil. A study in International Agrophysics on compaction and crop yields in Eastern European chernozems, for instance, found chernozem-grown barley plants yielded about half the amount of crops when highly compacted. Earlier work suggested compaction could impact yields for up to five years if it reached deep enough into the chernozem. For all but the worst compaction, though, several seasons of typical planting will help heal the land, says soil scientist DeAnn Presley of Kansas State University in Manhattan.

“If you had tank traffic go right through a crop field, the farmer is probably going to go out and just till up the field pretty well after the conflict is over. And you may never see that [compaction] again,” Presley says. Compaction “will definitely look terrible and you’ll have yield losses, but I don’t think they’ll be forever or permanent.”

A study of military vehicles rolling over prairie soils outside Fort Riley, Kan., revealed it took as little as one year for dry soil to recover from being compacted, but up to four years for wet soil to recover, both without tilling, scientists reported in Soil Science Society of America Journal. Tank traffic can alter the community of soil microbes and reduce the abundance of other organisms, like soil-aerating earthworms, for several years as well, members of the same team reported in Applied Soil Ecology.

Chernozems’ fluffiness might put it at greater risk of compaction, but it can also help the soil spring back afterward, helping prevent it from becoming a longer-term problem. Hardy, deep-rooting plants like some of Ukraine’s native grasses could also loosen stubborn soils, Presley says, but it would take years.

Chemical contamination

Countering compaction can be a relatively quick fix; not so with chemical contamination. Fuel spills, spent ammunition, chemical weapons, and animal and human remains can all foul the soil, sometimes for decades or longer.

Potentially toxic metals such as lead, arsenic and mercury can leach out of ammunition and weaponry and into the soil. Pollutants from warfare are still found in soils contaminated by wars as old as World War I, researchers reported in 2020 in Sustainability. At Ypres, a World War I battlefield in Belgium, scientists estimate that shells and artillery left more than 2,800 metric tons of copper in the top half-meter of soil. In Iran, soils remain laced with mercury and chlorine from the 1980s.

As crops grow, they can draw up these potentially toxic elements. Other elements, such as zinc and nickel, can severely stunt crop growth, says Ganga Hettiarachchi, a soil chemist also at Kansas State University. But soil contamination can be a hidden danger. If it doesn’t damage the plants, there may be no way of knowing if the soil is contaminated without careful testing, she says.

In some ways, chernozems are well-equipped to stop contaminants in their tracks in a matter of months. The soil’s organic matter and clay can trap toxic elements before they can enter a plant, sucking out contaminants – even in a matter of days in optimal lab conditions, Hettiarachchi says. But in real life, many chernozems are also slightly acidic, which can let those elements stay in a form that plants can take up for months before being stopped.

Because of this uncertainty, every potentially contaminated patch of soil must be checked to see if crops can be safely grown. “We have to monitor the soil and the crops as well, at least until we understand what’s going on,” says Hettiarachchi.

For some elements, farmers could remediate by planting plants known to extract those elements over time, says Hettiarachchi, but that would require several years of planting. Other options include altering the soils’ pH to lock away metals or adding extra fertilizer, which can also immobilize potentially toxic elements. But even after remediation occurs, farmers must test to see if soil conditions are keeping the contaminants locked away, or if the war is coming back to haunt them from the ground.

Depending on the extent of contamination, “it might not be possible for Ukrainian farmers to avoid growing in contaminated soils,” she says. Soil testing and time will tell.

Looking toward the future

With Russia’s bombardment of Ukraine still ongoing, the effect on the country’s soil is still uncertain. There are some hints, though. This isn’t the first time the Donbas region — a disputed area in eastern Ukraine — has come under fire. Russian-backed separatists attacked it beginning in 2014 too.

Scientists working in the Donbas to improve soil health there have faced a litany of challenges: The region’s agriculture already suffered from degradation due to irrigation waters polluted by coal mines, researchers reported in 2020 in Mineralogical Journal. Decades of intense farming had also taken a toll. Since 2014, conflict has exacerbated those problems, creating new issues and hampering scientists’ ability to help.

The region’s “chernozems have suffered and are experiencing irreparable military degradation,” Ukrainian soil scientists and a lawyer wrote in 2021 in Scientific Papers. Series A. Agronomy. “It is easy to predict [the degradation of chernozems], but very difficult to overcome.”

Even as the fighting has been concentrated in eastern Ukraine, this assessment now may apply to a far broader swath of the country. “Our unique soils, chernozems, are in unprecedented conditions,” representatives from Ukraine’s Institute for Soil Science and Agrochemistry Research wrote Science News in an e-mail. “The extent of the damage has yet to be ascertained. In fact, we have just begun to work in this direction … in difficult military conditions.”

It may seem like fun and games, but understanding how dominoes topple isn’t child’s play.

“It’s a problem that is so natural; everybody plays with dominoes,” says David Cantor, a researcher at Polytechnique Montreal with a background in civil engineering. So Cantor set out to create computer simulations of a row of dominoes collapsing in a chain reaction.

Domino games are more fun with a buddy — and so is research on the rectangular blocks. Cantor teamed up with a friend, physicist Kajetan Wojtacki of the Institute of Fundamental Technological Research of the Polish Academy of Sciences in Warsaw.

Friction is crucial for determining the speed at which the collapse cascades through a row of dominoes, the pair report in the June Physical Review Applied. That includes both the friction between colliding dominoes, and between the dominoes and the surface they sit on.

The computer simulations revealed the conditions needed for a speedy collapse. Toppling cascaded quickest for closely spaced dominoes that had little friction between them and that stood on a high-friction surface (SN: 8/1/19).

Less friction between dominoes — as occurs for tiles with more slippery surfaces — means less energy is lost. And more friction between the dominoes and the surface they stand on, such as rough felt, means that the tiles don’t slide too far backward as they fall. Such backsliding would otherwise slow the cascade.

In some simulations, the chain reaction stopped short. For instance, dominoes spaced far apart on a slippery surface backslid so much they avoided hitting each other.

Based on the simulations, the two domino dynamos came up with an equation that predicts the speed of collapse and showed that the predictions matched results of previous experiments. Turns out, there’s serious science behind the satisfying spectacle.

PASADENA, Calif. — The faint dwarf galaxies in a nearby galaxy group seem to have missed the memo. Instead of being dispersed evenly around the group’s most massive galaxy, which is what happens in our own galaxy group, these newly found dwarfs cluster in one region. And astronomers don’t know why.

“This satellite distribution is just weird,” astronomer Eric Bell said June 13 at the American Astronomical Society meeting.

Bell, of the University of Michigan in Ann Arbor, and colleagues used the Subaru telescope in Hawaii to hunt for faint clumps of stars, indicating dwarf galaxies, around the galaxy M81. This Milky Way–like galaxy is the most prominent member in a relatively nearby group of galaxies, all about 12 million light-years from Earth. The team found one definite dwarf galaxy and six possible fainter ones.

“The part that’s just bananas,” Bell said, is that the newfound satellite galaxies all sit on one side of M81.

Computer simulations of galaxy evolution suggest that the largest galaxies have many faint, small galaxies sprinkled uniformly throughout the outer part of the dominant galaxy’s diffuse cloudlike halo. Observations in our galaxy group back this up: The dozens of dwarf galaxies known to orbit in the Milky Way’s outskirts are distributed evenly around the galaxy, as are most of the dwarf galaxies seen around our nearest large neighbor, the Andromeda Galaxy (SN: 3/11/15; SN: 8/19/15).

But in the M81 group, the seven newly identified star clumps appear to surround a smaller member of that group, NGC 3077, which is about one-tenth the mass of M81. “The fact that the bigger thing doesn’t have more satellites,” Bell says, “nobody expects that.”

After a relaxing day at the Jersey Shore last July, Jessica Reeder and her son and daughter headed back home to Philadelphia. As they crested a bridge from New Jersey into Pennsylvania, they were greeted with a hazy, yellow-gray sky. It reminded Reeder of the smoky skies she saw growing up in Southern California on days when fires burned in the dry canyons.

Smelling smoke and worried about her asthma and her kids, Reeder flipped the switch to recirculate the air inside the car instead of drawing from the outside. At home, the family closed all the windows and turned their air purifiers on high.

The smoke had traveled from fires raging on the other side of the continent, in the western United States and Canada. Although air quality in Philadelphia didn’t come close to the record-bad air quality that some western cities experienced, it was bad enough to trigger air quality warnings — and not just for people with asthma or heart problems.

Most large U.S. wildfires occur in the West. But the smoke doesn’t stay there. It travels eastward, affecting communities hundreds to thousands of kilometers away from the fires. In fact, the majority of asthma-related deaths and emergency room visits attributed to fire smoke in the United States occur in eastern cities, according to a study in the September 2021 GeoHealth.

The big problem is fine particulate matter, tiny particles also known as PM_2.5. These bits of ash, gases and other detritus suspended in smoke are no more than 2.5 micrometers wide, small enough to lodge in the lungs and cause permanent damage. PM_2.5 exacerbates respiratory and cardiovascular problems and can lead to premature death. The particles can also cause asthma and other chronic conditions in otherwise healthy adults and children.

Over the last few decades, U.S. clean air regulations have cut down on particulate matter from industrial pollution, so the air has been getting cleaner, especially in the populous eastern cities. But the regulations don’t address particulate matter from wildfire smoke, which recent studies show is chemically different from industrial air pollution, potentially more hazardous to humans and increasing significantly.

So far, a lot of the research on how wildfire PM_2.5 can make people sick has been based on people living or working near fires in the West. Now, researchers are turning their attention to how PM_2.5 from smoke affects the big population centers in the East, far from the wildfires. One thing is clear: With the intensity and frequency of wildfires increasing due to climate change (SN: 12/19/20 & 1/2/21, p. 32), people across North America need to be concerned about the health impacts, says Katelyn O’Dell, an atmospheric scientist at George Washington University in Washington, D.C.

Bad air travels

Air pollution regulations limit PM_2.5 from exhaust-emitting cars and trucks and fossil fuel–burning factories and power plants. These regulations have done “a really good job” reducing anthropogenic air pollution in the last couple of decades, says Rosana Aguilera, an environmental scientist at the Scripps Institution of Oceanography in La Jolla, Calif. In the United States, concentrations of six of the most common air pollutants have dropped by 78 percent since the Clean Air Act of 1970, according to the U.S. Environmental Protection Agency. PM_2.5 concentrations have come down as well — at least until recently.

Western wildfires, which are growing more frequent, more severe and larger, are erasing some of the gains made in reducing industrial pollution, says Rebecca Buchholz, an atmospheric chemist at the National Center for Atmospheric Research in Boulder, Colo.

Fires in the Pacific Northwest are “driving an upward trend” in particulate matter air pollution, Buchholz and colleagues wrote April 19 in Nature Communications. Such smoke pollution peaks in August when fires in the region tend to spike and the atmosphere’s ability to clean itself through, say, rain, is limited. This spike of late-summer air pollution is new, Buchholz says. It’s especially noticeable since 2012.

And, as Reeder and her family experienced last year, transported wildfire pollution is causing substantial particulate matter spikes in the central United States and northeastern North America, Buchholz and colleagues found. Pacific Northwest wildfires thus “have the potential to impact surface air quality, even at large distances downwind of the wildfires,” the team wrote, putting some 23 million people in the central United States and 72 million in northeastern North America at increased risk of health impacts from the imported wildfire smoke.

How far and where PM_2.5 travels depends on weather patterns and how high wildfire smoke reaches — the stronger the fire, the longer it can last and the farther smoke can go, and thus the farther particulate matter can reach. Last year, far-away wildfires created unhealthy air quality conditions in locations from the Great Plains to New York City and Washington, D.C.

New York City saw some of its worst air quality in two decades. Philadelphia had two “code red” days — meaning air quality was unhealthy for all — because of the U.S. West and Canadian fires. In 2019, 2020 and 2021, those fires pushed PM_2.5 to unhealthy levels in much of Minnesota. In fact, a 2018 study showed that wildfire smoke plumes now waft above Minnesota for eight to 12 days per month between June and September.

Air safety yardstick

The Air Quality Index, or AQI, ranges from 0 to 500, based on the amount of pollution in the air at a given time. Ground-level ozone, particulate matter (both PM₁₀ and PM_2.5), carbon monoxide, sulfur dioxide and nitrogen dioxide are the primary parameters considered in the index. Code orange (above a score of 100) is unhealthy for people with heart and lung disease, older adults, children and people with diabetes. Code red and above (151–500) is unhealthy for everyone.

Human impacts

Smoke in the West is already having a tangible effect on human health in the East, says O’Dell, lead author of the 2021 GeoHealth study.

Reviewing smoke and health data from 2006 to 2018, O’Dell and colleagues found that more people visit emergency rooms and are hospitalized in the East than in the West from asthma problems attributable to smoke PM_2.5. Asthma-related ER visits and hospitalizations were higher east of the Rockies in 11 of the 13 years.

Over the study period, an average of 74 percent of asthma-related deaths and 75 percent of asthma ER visits and hospitalizations attributable to smoke occurred east of the Rockies. Of the estimated 6,300 excess deaths from asthma complications due to smoke PM_2.5 that occurred annually over the study period, more than 4,600 were in the East.

Smoke affects so many more people in the East primarily because more people live there, O’Dell notes. Her team defined “West” as west of the Rockies, with a population of 64 million, and “East” as east of the Rockies, home to 226 million people. In the West, smoke PM_2.5 causes a higher portion of regional asthma deaths. In the East, it’s a lower portion of the total population, but a far higher total number of people affected.

“We may be already seeing the consequences of these fires on the health of residents who live hundreds or even thousands of miles downwind,” Buchholz said in a press release.

August peaks

Although aerosols, including fine particulate matter, from Pacific Northwest fires have been increasing since 2002, they began a sharp increase in 2012, spiking in the warm, dry summer months. As smoke from the Northwest wafted eastward, similar smaller spikes were seen in the central United States and northeastern North America.

North American seasonal atmospheric aerosol levels, by region

Vulnerable youth

“Asthma is a very widespread, common health condition,” says Yang Liu, an environmental scientist at Emory University in Atlanta. In the United States, about 25 million people have asthma, or 8 percent of adults and 7 percent of children, according to the U.S. Centers for Disease Control and Prevention.

Fine particulate matter can spark asthma attacks, but it can also be a danger to people without the condition. Children are especially vulnerable primarily because of physiology. Children breathe faster so they end up taking in more particulate matter, plus their lungs are smaller so more of their lung surface is likely to be damaged when they breathe in particulate matter. And their lungs are still developing, says Jennifer Stowell, an environmental epidemiologist at Boston University School of Public Health.

Stowell led a study, reported in the January Environmental Research Letters, estimating how much wildfire smoke will exacerbate asthma attacks in the West. Stowell, Liu and colleagues estimate that, in the 2050s, there will be an additional 155,000 asthma-related ER visits and hospitalizations per wildfire season in the West just from smoke PM_2.5. The biggest concern, Stowell says, is for children and younger adults.

Aguilera, of Scripps, and her colleagues found associations between wildfire-specific PM_2.5 and pediatric respiratory-related ER and urgent care visits. In San Diego County from 2011 to 2017, wildfire-specific PM_2.5 was 10 times as harmful to respiratory health in children 5 and younger as ambient PM_2.5, the researchers reported in 2021 in Pediatrics. In fact, the same increase in levels of PM_2.5 from smoke versus ambient sources caused a 26 percent higher rate of ER or urgent care visits. The researchers didn’t note whether the children had preexisting asthma.

And even when a wildfire increased PM_2.5 by a small amount, respiratory ER and urgent care visits in kids 12 and under increased, Aguilera and colleagues reported in 2020 in the Annals of the American Thoracic Society. “Even relatively smaller wildfires can still generate quite an impact on the pediatric population,” Aguilera says. “And really, any amount of PM or air pollution is harmful.”

Studies of nonhuman primates have also shown permanent effects of smoke on the young — results researchers expect would also apply to humans, given genetic similarities. In 2008, a group of infant rhesus macaques at the California National Primate Research Center at the University of California, Davis was exposed to high PM_2.5 levels from a series of devastating wildfires in Northern California. Researchers have been comparing those monkeys with macaques born a year later that weren’t exposed to smoke.

At around age 3, macaques exposed to smoke displayed immune disorders and reduced lung capacity, lung function and lung volume, says Hong Ji, a molecular biologist at UC Davis and the primate center who wasn’t involved with this study. The lungs look like they had fibrosis, Ji says. “Early life smoke exposure … changed the trajectory of lung development,” and it doesn’t appear to be reversible, she says.

The monkeys exposed to wildfire PM_2.5 also have important changes to how their DNA works, Ji and colleagues reported in the January Environment International. Exposure to wildfire smoke in infancy can cause life-altering, long-term changes to the monkeys’ nervous and immune systems, as well as brain development, Ji says. Even worse, she says, the DNA changes are the type that can be passed down and may result in generational damage.

Even macaques born after in utero exposure to wildfire smoke can suffer cognitive, immune and hormone problems, primate center researchers reported April 1 in Nature Communications.

Now, Ji and colleagues have teamed with Rebecca Schmidt, a molecular epidemiologist at UC Davis who’s leading a study on the effects of wildfire smoke exposure on pregnant women and young children. This research group, as well as other teams, is also looking into whether PM_2.5 is causing genetic changes to babies exposed to smoke in utero, Ji says. The more results gathered on the effects of wildfire PM_2.5 on babies and children — and even in pregnancy — the more dangerous we realize it is, Ji says.

Chemical differences

Particulate matter changes as it travels through the atmosphere, both in volume and in chemistry. Some PM_2.5 is emitted directly from fires, and some is born from chemicals and trace gases emitted from fires that get chemically processed in the atmosphere, Buchholz says. Reactions that happen in the smoke plume, combined with sunlight, can create even more PM_2.5 downwind of the fires. How these particulates change chemically — through interactions between the atmosphere and the particulate matter, and between fire pollution and human pollution — and what that means for human health “is a really active area of research right now,” she says. “It’s super complicated.”

Epidemiological and atmospheric chemistry studies indicate that wildfire PM_2.5 is more hazardous to human health than ambient PM_2.5, says Stowell, the Boston epidemiologist. One such study compared particulate matter from Amazonian fires with urban sources such as vehicle exhaust in Atlanta. Nga Lee Ng, an atmospheric chemist at Georgia Tech, and colleagues found that smoke particulate matter is more toxic than urban particulate matter, “inducing about five times higher cellular oxidative stress,” Ng says. Oxidative stress damages cells and DNA in the body.

In addition, as smoke travels through the atmosphere and ages, it seems to become even more toxic, Ng says. Reactions between the particulate matter and sunlight and atmospheric gases change the particulate matter’s chemical and physical properties, rendering it even more potentially harmful. So, even though particulate matter dissipates over time and distance, “the health effects per gram are greater,” says Daniel Jaffe, an atmospheric chemist at the University of Washington Bothell.

That means that the studies of health effects near wildfires in the West may not represent the full story of how smoke from distant fires affects people in the East.

Liu, at Emory, hopes to see the U.S. government revisit policies related to what PM_2.5 levels are dangerous, since they’re based on ambient and not wildfire-related PM_2.5. In March, an EPA advisory panel recommended just that. In a letter to the agency, the Clean Air Scientific Advisory Committee wrote: “Regarding the annual PM_2.5 standard, all CASAC members agree that the current level of the annual standard is not sufficiently protective of public health and should be lowered.” The committee added, “There is substantial epidemiologic evidence from both morbidity and mortality studies that the current standard is not adequately protective.”

Local communities throughout the country need to determine when to close schools or at least keep kids inside, Liu says, as well as when to advise people to close windows and turn on air purifiers. Good masks — N95 and KN95 — can help too (yes, masks that block viruses can also block particulate matter).

City, county and state governments also need to prepare the health care system to respond to increased asthma issues, Liu says. Some states are starting to respond. In 2017, for example, the Minnesota Pollution Control Agency increased its air quality monitoring stations around the state from two to 18. The agency is also working with the National Weather Service, the Minnesota Department of Health and the Minnesota Department of Transportation to better communicate air quality warnings.

In the meantime, much more research is needed into the human health implications of increasing wildfire smoke, Buchholz says, as well as the chemical interactions in the atmosphere, how climate is changing fires, how fires change year after year, and how they impact the atmosphere, not to mention how different trees, buildings and other fuels affect particulate matter.

“Wildfires are perhaps one of the most visible ways that [climate change] is linked to health,” Stowell says. And the reality is, she says, “we’re going to see it remain as bad or worse for a while.”

The littlest kids in the United States are nearly done waiting for a COVID-19 vaccine.

On June 15, an advisory committee to the U.S. Food and Drug Administration voted unanimously in favor of emergency use authorization of Moderna’s and Pfizer-BioNTech’s mRNA vaccines for babies, toddlers and preschoolers. The step — a relief to many families of young children who’ve endured multiple COVID-19 surges, restricted outings and daycare disruptions — comes two and a half years after adults were first vaccinated against COVID-19 in December 2020 (SN: 12/18/20).

“This recommendation does fill a significant unmet need for a really ignored younger population,” said FDA committee member Michael Nelson, an allergist and immunologist at the University of Virginia School of Medicine in Charlottesville. “Families will now have a choice,” he said, adding that he hopes every child in the United States “gets vaccinated in the near future.”

Pending a recommendation from the U.S. Centers for Disease Control and Prevention, which is holding its advisory committee meetings on June 17 and 18, the first shots for the littlest kids could be available as early as June 21. According to plans released by the Biden administration, an initial 10 million doses for young children will come first, with millions more arriving in the following weeks. Families will be able to get the shots at pediatrician offices, community health centers, public health clinics, children’s hospitals and pharmacies, among other locations.

The FDA advisory committee meeting was a reminder yet again that the youngest are not free of risk from COVID-19. Among children, those 0 to 4 years old have the highest number of deaths compared with those who are older:  481 kids ages 0 to 4 have died, topping the 366, 382 and 310 reported in the 5–11, 12–15 and 16–17 year age groups, respectively, according to the CDC’s COVID Data Tracker as of June 16.

“We have to be careful that we don’t become numb to the number of pediatric deaths because of the overwhelming number of older deaths,” said Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, which oversees vaccine review, at the meeting.

And the winter surge driven by the omicron variant of the coronavirus did not spare the littlest kids: They experienced a considerable increase in cases and hospitalizations (SN: 3/1/22). For children under 5, there were 14.5 hospitalizations per 100,000 children in the United States during the peak of omicron, a rate five times as high than that seen during the delta variant’s peak, researchers reported in March in the Morbidity and Mortality Weekly Report.

Roughly 1 in 4 children under 5 hospitalized with COVID-19 end up in the intensive care unit, said pediatrician Evan Anderson of Emory University School of Medicine in Atlanta during a presentation at the FDA meeting. “Having cared for many children that have been in the ICU on ventilators for COVID … and having cared for several children that have died of COVID, we need to be able to prevent COVID-19,” Anderson said.

The seriousness of the illness means that “prevention is really the way to go,” said FDA committee member and pediatric infectious disease specialist Hayley Gans of Stanford University School of Medicine. The COVID-19 vaccine is “a breakthrough that has allowed us to move through the pandemic … [with] less suffering and disease.”

At the FDA advisory committee meeting, members reviewed immunity and safety data for  Moderna’s and Pfizer’s shots for the youngest children. The two vaccines have different dosing and timelines. Moderna’s mRNA COVID-19 vaccine for kids 6 months through 5 years is a two-dose series, 25 micrograms per dose, given four weeks apart. (Adults get two 100 microgram doses for their initial two-dose series of shots.)

Pfizer’s option, for kids 6 months through 4 years, is a three-dose series with 3 micrograms per dose. The first two shots are given three weeks apart, followed by a third dose at least eight weeks later. (The initial two-shot series for adults consists of 30-microgram doses.) Younger kids tend to get smaller doses of vaccines because of the need to balance their robust response to the shots with keeping expected side effects, like fever, manageable (SN: 2/25/21).

Determining how well a vaccine is expected to work in children is tested differently than in adults. The adult COVID-19 vaccine trials included tens of thousands of people per trial, enough to determine the efficacy of the vaccines (SN: 10/4/20). That’s a measure of how well the shots protect those in the vaccinated group compared with those given a placebo, based on how many cases occur in each group. For kids, it would have taken even larger trials to have enough COVID-19 cases (since overall totals among kids have been lower than for adults) for a close read on efficacy.

So as a proxy for efficacy, the trials compared the antibody response kids generate to the shots with what was measured for the youngest adults in the efficacy trials. For Moderna, the comparison group is 18- to 25-year-olds, while for Pfizer, the response is matched against those 16 to 25 years old (Pfizer included older teens in their adult trial).

Among more than 6,600 participants, Moderna reported that the little kids’ antibody response to its two-dose series met that seen among the young adult comparison group. Pfizer reported the same for the more than 4,500 participants in its young kids’ trial: the three-dose series produced antibody levels that reached that seen among the 16- to 25-year-old comparison group, which had gotten two shots.

The advisory committee also reviewed the safety of the vaccines for little kids. There were no alarming allergic reactions to the shots, no deaths and no cases of heart inflammation, a very rare side effect of COVID-19 mRNA vaccines (SN: 6/23/21) that poses a much higher risk during COVID-19 illness. Common side effects for both vaccines included sore arms, crying, irritability, sleepiness and fever.

Once the vaccines get the go-ahead, close to 20 percent of parents of the very young plan to be in line right away, according to the Kaiser Family Foundation’s COVID-19 Vaccine Monitor. The survey from mid-April reported that another 38 percent plan to wait and see how things go with the vaccine rollout before deciding, while 11 percent say they will get their youngest immunized only if the shots are required. That leaves 27 percent in the “definitely not” category, which is similar to the percentage of parents who say they won’t vaccinate kids 5 and up.

An issue that remains is whether the littlest kids will need boosters added to the initial series of shots, as adults and older kids have. And some FDA advisory committee members also stressed the need for clear communication around the shot options and schedules, since the Moderna and Pfizer jabs are different.

Safety monitoring will also continue, through different U.S. surveillance systems such as the Vaccine Adverse Event Reporting System. So far, around 600 million doses of the COVID-19 vaccines have been given in the United States, and the safety demonstrated is reassuring, said FDA committee member Henry Bernstein, a pediatrician at Cohen Children’s Medical Center in New Hyde Park, N.Y. “I think having a COVID vaccine available for this younger population is critically important, given that pediatric cases can be, [have] been and may be problematic in the future.”

Few marsupials have gone from miraculous survival to the brink of extinction as quickly as the Kangaroo Island dunnart.

In 2019 and 2020, devastating fires burned nearly 10 million hectares of southeastern Australia. The flames threatened hundreds of species with extinction, but the Kangaroo Island dunnart (Sminthopsis aitkeni) — which already numbered less than 500 before the fires — seemed to be one that defied expectations in the aftermath (SN: 3/9/21).

But now these rare creatures may be more at risk than ever, researchers say June 16 in Scientific Reports. The danger, as domestic as it sounds, is getting eaten by a cat.

As of 2008, invasive feral cats had contributed to at least 13 percent of extinctions worldwide. That’s one reason the government has been euthanizing cats on Kangaroo Island for years. The scientists who conducted the dunnart study knew all this — but when they studied the remains of cats euthanized in 2020, they were still surprised by what they saw: Seven out of 86 cats had recently dined on dunnart.

“We were not expecting to find so many,” says Louis Lignereux, a field researcher at the University of Adelaide School of Animal and Veterinary Science. It’s particularly bad news, he says, if you think of what was in the cats as only a snapshot of what they ate in the last 36 hours. Taking that into account, those seven cats alone could have eaten enough to wipe out the Kangaroo Island dunnart within a few months, if they had survived — and there are hundreds of other cats on the island.

A small habitat makes the dunnarts especially vulnerable. It’s like putting all your eggs in one basket, Lignereux says. Since the fires, the Kangaroo Island dunnart is thought to now live in an area about one-tenth of the size of Manhattan (SN: 1/13/20).

“If something happened to this spot,” he says, “then [the dunnart] is gone forever.”

“Pihoqahiak” means “ever-wandering one,” and is an Inuit name for the polar bear, a creature known to roam vast expanses of sea ice, sometimes plodding thousands of kilometers a year in search of seals.

But along the fjord-cut coastline of southeast Greenland, where the sea freezes over for just a few months of the year, some isolated polar bears are surviving as homebodies.

Unlike most polar bears, these bears don’t follow the sea ice during its annual recession or move onto land to hunt. Instead, the crafty ursids stalk seals on nearby glacial mélange — a floating mishmash of icebergs, sea ice fragments and snow that persists year-round near the front of glaciers in the fjords, researchers report in the June 17 Science.

“They’re residents in fjords that are sea ice–free for more than eight months of the year,” says Kristin Laidre, a biologist at the University of Washington in Seattle. “Normally, a polar bear wouldn’t be able to survive without sea ice for that long.”

For polar bears (Ursus maritimus), sea ice isn’t just frozen seawater; it’s the platform they usually use to hunt their preferred prey — seals. But as human-caused climate change raises Earth’s global temperature, that ice is disappearing. The number of polar bears that live on sea ice in the Beaufort Sea in the Arctic Ocean and Canada’s Hudson Bay is already declining. Researchers estimate that most other subpopulations of the bears will collapse by 2100 unless greenhouse gas emissions are curbed. The International Union for Conservation of Nature classifies the species as “vulnerable.”

The fjords of southeast Greenland and similar, limited areas could become a last, temporary refuge for a small number of bears, though only curbing climate change can save the ice-dependent species, Laidre and her colleagues say. Glacial mélange isn’t widespread in the Arctic, and what exists could disappear if temperatures rise too much.

Laidre and her colleagues estimate that several hundred bears may dwell in the fjords of southeast Greenland, though further work is needed to obtain a more precise count.

The southeast Greenland group came to the researchers’ attention while they were studying polar bears along east Greenland’s coast to provide advice to the Indigenous peoples who hunt the bears for subsistence. An analysis of 83 receiver-tagged polar bears from 1993 to 2021 revealed that, for the most part, bears living south of about 64° N latitude don’t interact with bears to the north, and vice versa.

Southeast Greenland bears may be mostly isolated by Greenland’s ice sheet to the west and a rapid current to the east, which could sweep seafaring bears south and stifle northward movement, the researchers say.

In northeast Greenland, the median distance traveled by tagged bears was 40 kilometers every four days. But in the southeast region, the median distance traveled was just 10 kilometers every four days, with bears sometimes traveling between neighboring fjords and sometimes remaining in the same fjord all year.

“For a polar bear, that’s nothing,” says Steven Amstrup, a zoologist and chief scientist of the conservation organization Polar Bears International, based in Bozeman, Mont., who was not involved in the study. “Apparently they’re finding enough resources there that they don’t have to make these huge, big movements.”

Southeast Greenland bears hunted on sea ice when it was present during a few months in winter and spring, the researchers found. For the rest of the year, the ursids used the glacial mélange that packed the fjords as hunting grounds.

“They use it just like sea ice,” Laidre says. “They’re able to walk [and hunt] on the mélange … and they can swim around between the pieces of ice and ambush seals.”

It’s not entirely surprising that polar bears have settled at the fronts — or toes — of glaciers in the fjords, Amstrup says. “Oftentimes, the toes of these glaciers are very productive areas,” he says, because glacial meltwater can flush nutrients from deeper in the ocean up toward the water’s surface. “You might expect that they would have seal populations [that] could support bears.”

The researchers also analyzed rare genetic variations in the southeast Greenland bears. That work revealed that the sampled animals shared a common ancestor about 200 years ago and have essentially kept to themselves since. “They’re the most genetically isolated polar bears in the world,” Laidre says. Conserving the distinctive bears will be important for protecting the species’ genetic diversity, which is already low, she says.

But for all their peculiarity, even southeast Greenland polar bears will perish without human climate action, Laidre and Amstrup agree (SN: 12/15/10). “Loss of Arctic sea ice is still the primary threat to all polar bears,” Laidre says. “This study does not change that.”

After two decades of debate, scientists are getting closer to figuring out exactly what the sun — and thus the whole universe — is made of.

The sun is mostly composed of hydrogen and helium. There are also heavier elements such as oxygen and carbon, but just how much is controversial. New observations of ghostly subatomic particles known as neutrinos suggest that the sun has an ample supply of “metals,” the term astronomers use for all elements heavier than hydrogen and helium, researchers report May 31 at arXiv.org.

The results “are fully compatible with [a] high metallicity” for the sun, says Livia Ludhova, a physicist at Research Center Jülich in Germany.

Elements heavier than hydrogen and helium are crucial for creating rock-iron planets like Earth and sustaining life-forms like humans. By far the most abundant of these elements in the universe is oxygen, followed by carbon, neon and nitrogen.

But astronomers don’t know exactly how much of these elements exist relative to hydrogen, the most common element in the cosmos. That’s because astronomers typically use the sun as a reference point to gauge elemental abundances in other stars and galaxies, and two techniques imply very different chemical compositions for our star.

One technique exploits vibrations inside the sun to deduce its internal structure and favors a high metal content. The second technique determines the sun’s composition from how atoms on its surface absorb certain wavelengths of light. Two decades ago, a use of this second technique suggested that oxygen, carbon, neon and nitrogen levels in the sun were 26 to 42 percent lower than an earlier determination found, creating the current conflict.

Another technique has now emerged that could decide the long-standing debate: using solar neutrinos.

These particles arise from nuclear reactions in the sun’s core that turn hydrogen into helium. About 1 percent of the sun’s energy comes from reactions involving carbon, nitrogen and oxygen, which convert hydrogen into helium but do not get used up in the process. So the more carbon, nitrogen and oxygen the sun actually has, the more neutrinos this CNO cycle should emit.

In 2020, scientists announced that Borexino, an underground detector in Italy, had spotted these CNO neutrinos (SN: 6/24/20). Now Ludhova and her colleagues have recorded enough neutrinos to calculate that carbon and nitrogen atoms together are about 0.06 percent as abundant as hydrogen atoms in the sun — the first use of neutrinos to determine the sun’s makeup.

And though that number sounds small, it’s even higher than the one favored by astronomers who support a high-metal sun. And it’s 70 percent greater than the number a low-metal sun should have.

“This is a great result,” says Marc Pinsonneault, an astronomer at Ohio State University in Columbus who has long advocated for a high-metal sun. “They’ve been able to demonstrate robustly that the current low-metallicity solution is inconsistent with the data.”

Still, because of uncertainties in both the observed and predicted neutrino numbers, Borexino can’t fully rule out a low-metal sun, Ludhova says.

The new work is “a significant improvement,” says Gaël Buldgen, an astrophysicist at Geneva University in Switzerland who favors a low-metal sun. But the predicted numbers of CNO neutrinos come from models of the sun that he criticizes as too simplified. Those models neglect the sun’s spin, which could induce mixing of chemical elements over its life and change the amount of carbon, nitrogen and oxygen near the sun’s center, thereby changing the predicted number of CNO neutrinos, Buldgen says.

Additional neutrino observations are needed for a final verdict, Ludhova says. Borexino shut down in 2021, but future experiments could fill the void.

The stakes are high. “We’re arguing about what the universe is made of,” Pinsonneault says, because “the sun is the benchmark for all of our studies.”

So if the sun has much more carbon, nitrogen and oxygen than currently thought, so does the whole universe. “That changes our understanding about how the chemical elements are made. It changes our understanding of how stars evolve and how they live and die,” Pinsonneault says. And, he adds, it’s a reminder that even the best-studied star — our sun — still has secrets.