Before ancient Egyptians, nature sculpted sphinxes. Here’s how
Posted on Wed, 29 Nov 2023 16:00:00 +0000

Steady winds can carve landforms called yardangs — thought to have inspired the Great Sphinx of Gaza — from featureless blobs, a new study suggests.

Creator: Elise Cutts

Guid: https://www.sciencenews.org/?p=3133461

The Great Sphinx of Giza might have been sculpted by desert winds long before it was ever touched by human hands.

Mysterious desert landforms called yardangs can bear an uncanny resemblance to seated lions — so much so that some researchers think one lionlike yardang might have had the honor of later being carved into the Sphinx by ancient Egyptians. The basic ingredients for these unusual rock formations might be rather simple, researchers report in the November Physical Review Fluids. Scientists were able to reliably sculpt hand-sized, sphinx-shaped yardangs from clay globs in a water tunnel so long as two basic conditions were met: consistent prevailing winds and a starting blob containing a mix of easily eroded and more resistant bits.

“This just came completely out of left field,” says geomorphologist Elena Favaro of the Open University in Milton Keynes, England, who was not involved in the study. Scientists aren’t sure exactly how yardangs start to form, but they appear in desert regions where winds wear exposed rock down into long, streamlined ridges facing into the prevailing winds. The study, Favaro says, is “a very inspired way to approach the problem” of how yardangs form.

Curious about how nature produces sphinxlike yardangs, New York University applied mathematician Leif Ristroph decided to take the question into his lab. He and his team study how natural shapes grow and change by compacting ages of erosion into experiments that last a few hours. They do this in a water tunnel, which is typically used to study fluid flow around stiff objects like wings.

“What we do, which is kind of abusive of the device,” Ristroph says, is “put things like a piece of ice in there and look how it changes shape” — or, “in this case, a chunk of mud.”

The team subjected their water tunnel to hundreds of muddy trials. Each time, they started with a stiff clay paste, sculpted it into a starting glob, embedded the glob with bits of hard plastic to represent harder parts of natural rock, and plopped the globs into the water tunnel to erode under a steady water “wind.”

Their setup reliably produced sphinxlike mini-yardangs. The initial shape of the glob and placement of the hard plastic bits didn’t matter much, so long as the plastic bits were in the windward half.

But because the sphinxes dissolved quickly, the team had to get creative to take pictures of the fluid flows that sculpted them. The researchers scanned their mini-yardangs and 3D-printed reusable plastic models of the forms. Before each experiment, they coated the plastic models with a thin veneer of clay laced with fluorescent dye.

In the water tunnel, the glowing clay allowed the researchers to trace the whorling currents around the blob. This revealed a few patterns that the team is now working to model mathematically, including a turbulent “mane” of eddies cast from behind the sphinx’s head that carves out a sloping, feline spine. Whether centimeter-scale blobs in water say anything about landscape-sized rocks eroded by wind is a question Ristroph hopes the new study can tempt geomorphologists into answering.

This bird hasn’t been seen in 38 years. Its song may help track it down
Posted on Wed, 29 Nov 2023 14:22:07 +0000

Using bioacoustics, South American scientists are eavesdropping on a forest in hopes of hearing the song of the long-missing purple-winged ground dove.

Creator: Meghie Rodrigues

Guid: https://www.sciencenews.org/?p=3133324

How do you look for an animal you don’t even know exists anymore?

The last sighting of the purple-winged ground dove (Paraclaravis geoffroyi) — a small, bamboo-loving dove native to the South American Atlantic Forest in Brazil, Argentina and Paraguay — was in 1985. But, researchers wondered, was it possible to capture the elusive bird’s sound in the wild to find out if any individuals are left?

It’s not an unheard-of idea. Scientists have used bioacoustics — a subfield of ecology that relies on sound to make environmental analyses — for everything from recording dolphins’ communication patterns to studying bats from afar to avoid virus spillover from humans (SN: 12/7/17; SN: 10/23/22). With artificial intelligence, it is now possible to use large audio datasets to train algorithms to spot different animal sounds within the cacophony of a natural background.

But the problem is that recordings of the purple-winged ground dove singing are as rare as the bird itself.

“I came across [the bird’s song] watching a 1985 interview with Carlos Keller, a former bird breeder in São Paulo state, who had a few individuals of the dove,” says Carlos Araújo, an ecologist at the Instituto de Biología Subtropical at the Universidad Nacional de Misiones in Argentina. “And they sang while he spoke.”

With Keller’s help, Araujo and colleagues accessed the decades-old recording and isolated the bird’s song.

The next challenge was to see if it was even possible to identify individual bird songs amidst the sounds of other birds chirping, leaves rustling, rain falling, insects whirring and gnawing and larger animals moving through the forest.

“We took a step back and did some analyses with other birds that are critically endangered but there are known individuals,” Araújo says. The team focused on three species found in Foz do Iguaçu, a national park that straddles the border of Brazil and Argentina: the cherry-throated tanager (Nemosia rourei), the Alagoas antwren (Myrmotherula snowi) and the blue-eyed ground-dove (Columbina cyanopis). These birds live in the same environments as the purple-winged ground dove. And the blue-eyed ground dove’s story inspires hope: The species went missing in 1941 and was rediscovered in 2016.

The researchers installed 30 recorders in strategic spots along green areas in the Brazilian part of Foz do Iguaçu and recorded from July 2021 to April 2022. They also used data from another 100 recorders on the Argentinian side of Foz.

“We went looking for the Guadua trinii bamboo to place the recorders,” says Benjamin Phalan, Head of Conservation at Parque das Aves, a private institution in Foz do Iguaçu focused on the conservation of Atlantic Forest birds. Like the purple-winged ground dove, the three bird species follow the flowering season of the G. trinii bamboo, which happens about once every 30 years.

The team pushed through thickets of bamboo, braved ticks and biting flies, and watched out for venomous snakes such as jacaracas pit vipers. Bumping into these snakes is “rare but can happen. So we use galoshes or gaiters to protect us in case anyone steps on a snake or near it,” Phalan says.

The recorders captured one minute of landscape sound every 10 minutes and generated about 3,000 days’ worth of recordings. “A lot of data to sift through,” says Araújo.

Readily available analysis software wouldn’t work. These software, Araújo says, “need a lot of data input. With such rare species, we just don’t have that much data to train the identification algorithm.”

So the team started from scratch, working with the little data they had for the three endangered birds. First, Araújo created a signal template — exactly like the birds’ singing — based on just a few recordings. The algorithm then compares that template with the soundscape recordings, separating signal from noise. If it spots a sound that is similar to the template, chances are that it is the bird that the researchers are looking for.

The method relies on a statistical model “that is not new, but was used in a very clever and unusual way,” says David Donoso, an ecosystem ecology researcher at the Technische Universität Darmstadt in Germany. Donoso and colleagues recently used bioacoustics to investigate the recovery of Choco, a biodiversity hot spot in Ecuador that had been transformed in an agricultural area.

There are different approaches to bioacoustics depending on what you’re looking for, Donoso says. “You can either use fewer recordings to map a whole animal soundscape to tell what species are there, like we did, or you can use lots of recordings to look for a single sound pattern,” he says. The study at Foz do Iguaçu “shows that you can use a relatively simple model to answer a complex question — and it works.”

The tool worked reasonably well to identify the cherry-throated tanager and blue-eyed ground-dove singing, but not so much for the Alagoas antwren, Araújo’s team reports October 23 in Bioacoustics. “We’re trying to understand what happened, but we know that the algorithm works,” he says.

The next step, Araújo says, is to refine the algorithm’s precision to find the Alagoas antwren and train it to look for the purple-winged ground dove. And they will do so at the same time. “We’re aiming at both goals at once because we’re running against the clock to find these birds,” Araújo says. “In the end, we are looking for a ghost.” But not a silent one, he hopes. 

Capturing methane from the air would slow global warming. Can it be done?
Posted on Tue, 28 Nov 2023 15:00:00 +0000

Removing methane from the atmosphere requires different technology from removing carbon dioxide. Scientists are taking on the challenge.

Creator: Katherine Bourzac

Guid: https://www.sciencenews.org/?p=3133428

This summer was the hottest ever recorded on Earth, and 2023 is on track to be the hottest year. Heat waves threatened people’s health across North America, Europe and Asia. Canada had its worst wildfire season ever, and flames devastated the city of Lahaina in Maui. Los Angeles was pounded by an unheard-of summer tropical storm while rains in Libya caused devastating floods that left thousands dead and missing. This extreme weather is a warning sign that we are living in a climate crisis, and a call to action.

Carbon dioxide emissions from burning fossil fuels are the main culprit behind climate change, and scientists say they must be reined in. But there’s another greenhouse gas to deal with: methane. Tackling methane may be the best bet for putting the brakes on rising temperatures in the short term, says Rob Jackson, an Earth systems scientist at Stanford University and chair of the Global Carbon Project, which tracks greenhouse gas emissions. “Methane is the strongest lever we have to slow global warming over the next few decades.”

That’s because it’s relatively short-lived in the atmosphere — methane lasts about 12 years, while CO₂ can stick around for hundreds of years. And on a molecule-per-molecule basis, methane is more potent. Over the 20-year period after it’s emitted, methane can warm the atmosphere more than 80 times as much as an equivalent amount of CO₂.

We already have strategies for cutting methane emissions — fixing natural gas leaks (methane is the main component of natural gas), phasing out coal (mining operations release methane), eating less meat and dairy (cows burp up lots of methane) and electrifying transportation and appliances. Implementing all existing methane-mitigation strategies could slow global warming by 30 percent over the next decade, research has shown.

But some climate scientists, including Jackson, say we need to go further. Several methane sources will be difficult, if not impossible, to eliminate. That includes some human-caused emissions, such as those produced by rice paddies and cattle farming — though practices do exist to reduce these emissions (SN: 11/28/15, p. 22). Some natural sources are poised to release more methane as the world warms. There are signs that tropical wetlands are already releasing more of the gas into the atmosphere, and rapid warming in the Arctic could turn permafrost into a hot spot for methane-making microbes and release a bomb of methane stored in the currently frozen soil.

So scientists want to develop ways to remove methane directly from the air.

Three billion metric tons more methane exist in the atmosphere today than in preindustrial times. Removing that excess methane would cool the planet by 0.5 degrees Celsius, Jackson says.

Similar “negative emissions” strategies are already in limited use for CO₂. That gas is captured where it’s emitted, or directly from the air, and then stored somewhere. Methane, however, is a tricky molecule to capture, meaning scientists need different approaches.

Most ideas are still in early research stages. The National Academies of Sciences, Engineering and Medicine is currently studying these potential technologies, their state of readiness and possible risks, and what further research and funding are needed. Some of the approaches include re-engineering bacteria that are already pros at eating methane and developing catalytic reactors to place in coal-mine vents and other methane-rich places to chemically transform the gas.

“Methane is a sprint and CO₂ is a marathon,” says Desirée Plata, a civil and environmental engineer at MIT. For scientists focused on removing greenhouse gases, it’s off to the races.

Microbes already remove methane from the air

Methane, CH₄, is readily broken down in the atmosphere, where sunshine and highly reactive hydroxyl radicals are abundant. But it’s a different story when chemists try to work with the molecule. Methane’s four carbon-hydrogen bonds are strong and stable. Currently, chemists must expose the gas to extremely high temperatures and pressures to break it down.

Even getting hold of the gas is difficult. Despite its potent warming power, it’s present in low concentrations in the atmosphere. Only 2 out of every 1 million air molecules are methane (by comparison, about 400 of every 1 million air molecules are CO₂). So it’s challenging to grab enough methane to store it or efficiently convert it into something else.

Nature’s chemists, however, can take up and transform methane even in these challenging conditions. These microbes, called methanotrophs, use enzymes to eat methane. The natural global uptake of methane by methanotrophs living in soil is about 30 million metric tons per year. Compare that with the roughly 350 million tons of methane that human activities pumped into the atmosphere in 2022, according to the International Energy Agency.

Microbiologists want to know whether it’s possible to get these bacteria to take up more methane more quickly.

Lisa Stein, a microbiologist at the University of Alberta in Edmonton, Canada, studies the genetics and physiology of these microbes. “We do basic research to understand how they thrive in different environments,” she says.

Methanotrophs work especially slowly in low-oxygen environments, Stein says, like wetland muck and landfills, the kinds of places where methane is plentiful. In these environments, microbes that make methane, called methanogens, generate the gas faster than methanotrophs can gobble it up.

But it might be possible to develop soil amendments and other ecosystem modifications to speed microbial methane uptake, Stein says. She’s also talking with materials scientists about engineering a surface to encourage methanotrophs to grow faster and thus speed up their methane consumption.

Scientists hope to get around this speed bump with a more detailed understanding of the enzyme that helps many methanotrophs feast on methane. Methane monooxygenase, or MMO, grabs the molecule and, with the help of copper embedded in the enzyme, uses oxygen to break methane’s carbon-hydrogen bonds. The enzyme ultimately produces methanol that the microbes then metabolize.

Boosting MMO’s speed could not only help with methane removal but also allow engineers to put methanotrophs to work in industrial systems. Turning methane into methanol would be the first step, followed by several faster reactions, to make an end product like plastic or fuel.

“Methane monooxygenases are not superfast enzymes,” says Amy Rosenzweig, a chemist at Northwestern University in Evanston, Ill. Any reaction involving MMO will impose a speed limit on the proceedings. “That is the key step, and unless you understand it, it’s going to be very difficult to make an engineered organism do what you want,” Rosenzweig says.

Enzymes are often shaped to fit their reactants — in this case, methane — like a glove. So having a clear view of MMO’s physical structure could help researchers tweak the enzyme’s actions. MMO is embedded in a lipid membrane in the cell. To image it, structural biologists have typically started by using detergents to remove the lipids, which inactivates the enzyme and results in an incomplete picture of it and its activity. But Rosenzweig and colleagues recently managed to image the enzyme in this lipid context. This unprecedented view of MMO in its native state, published in 2022 in Science, revealed a previously unseen site where copper binds.

But that’s still not the entire picture. Rosenzweig says she hopes her structural studies, along with other work, will lead to a breakthrough soon enough to help forestall further consequences of global warming. “Maybe people get lucky and engineer a strain quickly,” Rosenzweig says. “You don’t know until you try.”

Chemists make progress on catalysts

Other scientists seek to put methane-destroying chemical reactors close to methane sources. These reactors typically use a catalyst to speed up the chemical reactions that convert methane into a less planet-warming molecule. These catalysts often require high temperatures or other stringent conditions to operate, contain expensive metals like platinum, and don’t work well at the concentrations of methane found in ambient air.

One promising place to start, though, is coal mines. Coal mining is associated with tens of millions of tons of methane emissions worldwide every year. Although coal-fired power plants are being phased out in many countries, coal will be difficult to eliminate entirely due to its key role in steel production, says Plata, of MIT.

To develop a catalyst that might work in a coal mine, Plata found inspiration in MMO. Her team developed a catalyst material based on a silicate material embedded with copper — the same metal found in MMO and much less expensive than those usually required to oxidize methane. The material is also porous, which improves the catalyst’s efficiency because it has a larger surface area, and thus more places for reactions to occur, than a nonporous material would. The catalyst turns methane into CO₂, a reaction that releases heat, which is needed to further fuel the reaction. If methane concentrations are high enough, the reaction will be self-sustaining, Plata says.

Turning methane into CO₂ may sound counterproductive, but it reduces warming overall because methane traps much more heat than CO₂ and is far less abundant in the atmosphere. If all the excess methane in the atmosphere were turned into CO₂, according to a 2019 study led by Jackson, it would result in only 8.2 billion additional tons of CO₂ — equivalent to just a few months of CO₂ emissions at today’s rates. And the net effect would be to lessen the heating of the atmosphere by a sixth.

Cattle feedlots are another place where Plata’s catalytic reactor might work. Barns outfitted with fans to keep cattle comfortable move air around, so reactors could be fitted to these ventilation systems. The next step is determining whether methane concentrations at industrial dairy farms are high enough for the catalyst to work.

Another researcher making progress is energy scientist and engineer Arun Majumdar, one of Jackson’s collaborators at Stanford. In January, Majumdar published initial results describing a catalyst that converts methane into methanol, with an added boost from high-energy ultraviolet light. This UV blast adds the energy needed to overcome CH₄’s stubborn bonds — and the carefully designed catalyst stays on target. Previous catalyst designs tended to produce a mix of CO₂ and methanol, but this catalyst mostly sticks to making methanol.

Is geoengineering a path to methane removal?

A more extreme approach to speed up methane’s natural breakdown is to change the chemistry of the atmosphere itself. A few companies, such as the U.S.-based Blue Dot Change, have proposed releasing chemicals into the sky to enhance methane oxidation.

Natalie Mahowald, an atmospheric chemist at Cornell University, decided to evaluate this type of geoengineering.

“I’m not super excited about throwing more things into the atmosphere,” Mahowald says. To meet the goals of the Paris Agreement, limiting global warming to 1.5 to 2 degrees Celsius above the preindustrial average, though, it’s worth exploring all possibilities, she says. “If we’re going to meet these targets,” she says “we’re going to need some of these crazy ideas to work. So I’m willing to look at it. But I’m looking with a scientist’s critical eye.”

The main strategy proposed by advocates would inject iron aerosols into the air over the ocean on a sunny day. These aerosols would react with salty sea spray aerosols to form chlorine, which would then attack methane in the atmosphere and initiate further chemical reactions that turn it into CO₂. Mahowald wondered how much chlorine would be needed — and if there might be any unintended consequences.

Detailed modeling revealed something alarming. The iron injections could have the opposite of the intended effect, Mahowald and colleagues reported in July in Nature Communications. Chlorine won’t attack methane if ozone is around. Instead, chlorine will first break down all the ozone it can find. But ozone plays a key role in generating the hydroxyl radicals that naturally break down atmospheric methane. So when ozone levels fall, Mahowald says, the concentration and lifetime of methane molecules in the atmosphere actually increases. To use this strategy to break down methane, geo­engineers would need to add a tremendous amount of chlorine to the atmosphere — enough to first break down the ozone, then attack methane.

Removing 20 percent of the atmosphere’s methane, thus reducing the planet’s surface temperature by 0.2 degrees Celsius by 2050, for example, would require creating about 630 million tons of atmospheric chlorine every year. That would in turn require injecting perhaps tens of millions of tons of iron. A form of particulate matter, these iron aerosols could worsen air quality; inhaling particulate matter is associated with a range of health problems, particularly cardiovascular and lung disease. This atmospheric tinkering could also create hydrochloric acid that could reach the ocean and acidify it.

And there’s no guarantee that some of the chlorine wouldn’t make it all the way up to the ozone layer, depleting the planetary shield that protects us from the sun’s harmful UV rays. Mahowald is still studying this possibility.

Methane is a sprint and CO₂ is a marathon.

Desirée Plata

Mahowald is ambivalent about doing research on geoengineering. “We’re just throwing out ideas here because we’re in a terrible, terrible position,” she says. She’s worried about what could happen if all the methane locked up in the world’s permafrost escapes. If scientists can figure out how to use iron aerosols effectively, without adverse effects — and if such geoengineering is accepted by society — we might need it.

“We’re just trying to see, is there any hope this could work and would we ever want to do it? Would it have enough benefits to outweigh the disadvantages?”

The committee organized by the National Academies to investigate methane removal is taking these kinds of ethical questions into account, as well as considering the potential cost and scale of technologies. Stein, a committee member, says a framework proposed by Spark Climate Solutions provides some guidance. The organization, a nonprofit based in San Francisco that evaluates methane-removal technologies, proposes investing in tech that can remove tens of millions of tons of methane per year in the coming decades, at a cost of less than $2,000 per ton. Spark cofounder David Mann says the numbers are designed to focus attention and investment on technologies that can make a real difference in curbing climate change in the near term.

The National Academies group aims to make recommendations about research priorities on methane-removal technologies by next summer. It’s likely that a portfolio of different technologies will be necessary. What works in a cattle feedlot may not work at a wastewater treatment plant, for instance.

Scientists focused on methane removal are eager for more researchers, research funding and companies to enter the fray — and quickly. “It’s been a crazy year,” Jackson says of 2023’s extreme weather. We’re already feeling the effects of global warming, but we can seize the moment, he says. “This problem is not something for our grandchildren. It’s here.”

One mountain in Brazil is home to a surprising number of these parasitic wasps
Posted on Tue, 28 Nov 2023 12:00:00 +0000

Darwin wasps were thought to prefer temperate areas. But researchers scoured a mountain in the Brazilian tropics and found nearly a hundred species.

Creator: Darren Incorvaia

Guid: https://www.sciencenews.org/?p=3133291

The tropics are teeming with life, tending to hold far more species than milder environments closer to the poles. But one group of insects, the Darwin wasps, were thought to buck that trend.

Researchers who compared wasp diversity in the United Kingdom and the United States with tropical areas in the 1970s and ’80s concluded that these wasps were most diverse at mid-latitudes — say, Kentucky or England. But others thought that people just weren’t looking hard enough in the tropics.

It’s easy to look for wasps in a British garden, says Peter Mayhew, but “it’s very hard to do long-term work” in a tropical rainforest. Mayhew, a biologist at the University of York in England, was up to the challenge.

Now, after years of sifting through wasps collected from a single mountain in the Brazilian Atlantic rainforest a decade ago, Mayhew and colleagues have identified nearly 100 Darwin wasp species. The result, published November 7 in the journal Insects, suggests that the tropics are home to far more types of the wasp than was previously recognized.

Darwin wasps are one family of parasitic wasps, the Ichneumonidae, which lay their eggs on or inside other creepy-crawlies so that the hatched larvae have a ready-made meal (SN: 7/28/56; SN: 8/5/15). In this way, the Alien-esque wasps help control the populations of their prey, serving a vital ecological role similar to that of apex predators like wolves and sharks. With 25,000 described species, there are more kinds of Darwin wasp than there are known mammal and bird species combined.

To understand where the wasps might live in the tropics, Mayhew and his Brazilian colleagues took a hike, several in fact. The team trekked up a mountain in Brazil’s Serra dos Órgãos National Park, placing pairs of traps known as Malaise traps at 15 sites along the way. The path started along a road, which made carting the traps — each consisting of a tent and a jar of alcohol weighing about a kilogram — relatively simple.

After that, though, the team had to carry them by hand up through the jungle. “The first hour is pure hell,” Mayhew recalls. “Very steep, very hot and very humid.” After laying the traps, members of the team returned every month for one year to swap the jars for fresh ones.

The rainforest is, unsurprisingly, full of critters, which led to each alcohol jar becoming what Mayhew calls “insect soup.” To simplify things for now, the researchers chose to focus on only half of the sample jars and look specifically for one subfamily of Darwin wasps called the pimplines.

With the help of an “army of undergraduates” and taxonomist Ilari Sääksjärvi of the University of Turku in Finland, the team identified 98 pimpline species, only 24 of which have been previously described and named. What’s more, there tended to be fewer pimpline species as researchers scaled the mountain — but the higher-elevation species weren’t found lower down. For comparison, the British Isles have 109 known pimpline species, and wasp diversity there has been sampled much more than in Brazil.

Based on this study, Mayhew says, middle to low elevations in the tropics could be targeted for protection in order to conserve the most Darwin wasp diversity there and preserve the insects’ key ecological role. “[At] 1,500 meters and below is where you get quite a lot,” he says.

The new research is “more evidence that, yes, this wonderful group of really interesting wasps has this amazing unexplored diversity in the tropics, and we need more people working on them,” says Laura Timms, a conservation biologist at Canada’s Credit Valley Conservation in Mississauga who was not involved with the research.

Mayhew next hopes to examine other types of Darwin wasp that were collected in the insect soup to see if they are as diverse as the pimplines.

The wealth of creatures collected in the traps could also be useful to researchers interested in other insects too, Mayhew says, such as leaf beetles and fireflies. “Quite a lot of what’s in those bottles is going to be new to science.”

Some picky Australian mosquitoes may target frog nostrils for blood
Posted on Mon, 27 Nov 2023 15:00:00 +0000

The insects seem to sip from nowhere else on frogs’ bodies. Thinner skin or denser blood vessels near the nostrils might explain why.

Creator: Jake Buehler

Guid: https://www.sciencenews.org/?p=3133341

An Australian mosquito species knows the best spot to drink its bloody meals: a frog’s nostril.

The bloodsuckers are surprisingly selective when dining on frogs, seemingly picking no other place on the body to feast, researchers report November 21 in Ethology. Frogs’ sniffers may be an easy and productive place for the mosquitoes to pierce the thin skin and drink up. The new finding could one day help scientists better understand the transmission of some frog diseases.

Behavioral biologist John Gould discovered the nostril-nibbling insects while studying frogs in ponds on Australia’s Kooragang Island. From 2020 through 2022, Gould occasionally noticed mosquitoes on the faces of the frogs he was surveying and would take photos.

“It was only once I laid out all the photos together that I realized something very particular and surprising was happening,” says Gould, of the University of Newcastle in Callaghan, Australia.  In the 12 photos that Gould took of mosquitoes on frogs, every single bloodsucker was feeding on the skin of the frog’s nostril. 

Some mosquitoes feed only on frogs and toads but bite various parts of the body. The mosquito that caught Gould’s eye, Mimomyia elegans, has a generalized diet of amphibians, mammals and birds. “Yet its feeding strategy when using frogs appears to be highly specialized,” Gould says.

The nostril skin may be especially soft and thin, making it easier for the mosquito’s biting mouthparts to pierce, Gould says. Alternatively, he notes, there could be a high density of blood vessels near the surface of the nostril skin. 

Dining at this venue on a renowned insect eater is risky, considering the nostrils rest just above a powerful, sticky tongue (SN:10/5/22). But the mosquitoes might have a stealthy work-around. Gould observed some of the mosquitoes landing on the frogs’ backs first before carefully walking up toward the head. This, he says, might keep them from being detected and eaten. 

Gould and colleagues have shown in previous work that mosquitoes may be vectors for amphibian chytrid fungus, a grave threat to amphibians globally. “Determining where exactly mosquitoes land and subsequently feed on frogs may allow scientists to better understand the spread of the infection across the skin surfaces of frogs,” he says.

Some of the photographed mosquitoes were feeding on green and golden bell frogs (Litoria aurea). Those frogs are considered vulnerable to extinction, in part due to habitat loss, by the International Union for Conservation of Nature.

A laboratory experiment to carefully watch frogs and mosquitoes to confirm the insects’ nasal predilections would be helpful, says Manuela Carnaghi, an insect behavioral ecologist at the University of Greenwich in Chatham, England, who was not involved with the study.

Determining precisely how mosquitoes target and bite multiple kinds of hosts is key for understanding disease transmission in animals, Carnaghi says. It’s particularly important, she says, when considering the ability of a mosquito-borne pathogen or parasite to jump between different species. 

Reindeer herders and scientists collaborate to understand Arctic warming
Posted on Mon, 27 Nov 2023 13:00:00 +0000

Siberian reindeer herders and scientists are working together to figure out how to predict rain-on-snow events that turn tundra into deadly ice.

Creator: Sujata Gupta

Guid: https://www.sciencenews.org/?p=3133109

The spring 2014 annual reindeer festival in Yar-Sale, a rural town on the Yamal Peninsula in Western Siberia, was a grim affair. A rainstorm followed by a deep freeze the previous November had turned the normally snow-covered tundra into an ice shield. Reindeer could not paw through the thick ice to access lichen, their primary food source. In a region where winter temperatures can plunge below –50° Celsius, that ground remained frozen months later. Tens of thousands of reindeer had already died of starvation. Thousands more were on the brink of death.

A prominent reindeer herder named Vasily Serotetto approached a group of scientists. Could they predict when such an event — known as seradt in the Indigenous Nenets language — might occur, he asked. Even a few days advance notice would have enabled mobile slaughterhouse operators to come in and humanely kill the animals. And the animal meat and fur would not have gone to waste.

To the scientists in attendance, the request felt like a call to action. Serotetto was basically saying: “You scientists, what’s causing this?” says Bruce Forbes, a biogeographer at the University of Lapland in Rovaniemi, Finland.

The scientists possessed a trove of satellite images of the Russian Arctic to start tackling that question, Forbes knew. But without more detailed, on-the-ground information from local inhabitants, such as the timing of the event and where it occurred, they did not know where to begin looking in that massive amount of data.

Now the two groups have joined forces to try to understand a phenomenon that has crucial implications for a people’s way of life, as well as a world at large grappling with climate change. Besides preventing herbivores from accessing foliage underneath the ice, rain on snow has been shown to trigger slush avalanches, create surface conditions that warm permafrost, change soil and vegetation conditions and disrupt transportation and communications.

While that paired knowledge helped unravel the many factors that caused the deadly icing in 2013, finding a way to predict such events remains a puzzle.

Power of partnership

The idea that Indigenous and scientific communities can help each other has been gaining prominence in recent years. Forbes is part of a group of interdisciplinary scientists involved in the Arctic Rain on Snow Study, or AROSS, which is funded by the National Science Foundation. The team is studying what causes rain on snow in the Arctic and how such events affect local wildlife, ecology and communities.

And in September, NSF launched a research hub, the Center for Braiding Indigenous Knowledges and Science. That $30-million, five-year effort to bridge Western and Indigenous ways of knowing is based at the University of Massachusetts Amherst.

Indigenous people, such as the Siberian reindeer herders, have a deep understanding of their local environs, says linguistic anthropologist Roza Laptander, an AROSS team member originally from the Yamal Peninsula. Laptander, of both the University of Lapland and the University of Hamburg in Germany, has periodically embedded with herding communities since 2006.

Laptander’s research shows how ecological knowledge is encoded in the Nenets language. For instance, the first snow of the season is often soft and deep, or idebya syra, Laptander reported in September in Ecology and Society. That snow is difficult for the reindeer to walk in. Snow with ice granules, or inggyem’ syra, indicates high-quality lichen. Seradt, caused by rain falling on snow or unfrozen ground and then freezing solid, is to be feared. The word stems from serad’’, which translates to both rain and misfortune.

Historically, the herders could rely on their in-depth knowledge of varying types of snow and ice, along with an ability to read weather patterns and animal behavior, to gauge the likelihood of a difficult winter, Laptander says. But a rapidly warming Arctic is scrambling those signals. “Their traditional ways of predicting weather do not work anymore,” she says.

Scientists, meanwhile, often look to understand how warming-fueled changes to the Arctic climate, such as thinning sea ice and melting permafrost, are affecting climate change and weather patterns on a global scale (SN: 8/31/23). Knowing where to zoom in and what to zoom in on to help local communities requires those communities’ input.

“[Scientists] probably wouldn’t even know one type of snow is different than another. We might just look and say, ‘There’s snow here,’” says Dylan Davis, a remote sensing archaeologist at Columbia University who is not involved with this project. “Local communities and Indigenous communities that live with this every day, they’re going to be able to see things that we don’t.”

Prediction challenges

That’s what happened at Yar-Sale. Forbes told Serotetto that scientists might be able to sort out what caused the 2013–14 seradt, but they needed an idea of where to begin. Serotetto pointed to a map. In a typical winter, herders migrate from north to south. When the rain-on-snow event hit, many herders were already too far south to turn back or doubted the severity of the disaster. Serotetto, a herder with decades of experience, was able to push north. He discovered that the northern peninsula was relatively unscathed.

Serotetto drew a line on the map demarcating where he had come across the edge of the ice shield. When scientists pulled up satellite images from that November day, Forbes says, “the line was exactly where he drew it.” 

That information enabled Laptander, Forbes and others on the team to begin investigating the unique confluence of sea ice levels, snow versus ice cover on land, air temperatures and precipitation that contributed to the November 2013 icing event in southern Yamal.

Melting sea ice in the Barents and Kara seas releases humid air into the atmosphere, the team found (SN: 11/15/16). That humid air can blow onto the land as rain when temperatures rise above freezing.

The answer to Serotetto’s question, though, is far from resolved. Predicting such events remains extremely challenging, Forbes says. For instance, in 2018, the North Atlantic was open water all the way to the North Pole, and rain-on-snow seemed almost inevitable. But such an event did not occur. How did conditions differ between 2013 and 2018?

Efforts to answer that question are currently on hold. First, the pandemic thwarted travel and then, in February 2022, Russia invaded Ukraine. Climate research in the Russian Arctic has come to a virtual standstill, Forbes says. “Suddenly, half the Arctic is a no-go.”  

But the work in Yamal has snowballed to other Arctic regions, Forbes says. For instance, on a trip to Greenland last year, sheep farmers and reindeer herders told Forbes that they had just dealt with their first serious rain-on-snow event the previous winter. Forbes and his colleagues are hoping to apply what they learned in Yamal to better understand that event. “Now we have a data-sharing network with Indigenous informants across Arctic North America,” Forbes says.

A rare, extremely energetic cosmic ray has mysterious origins
Posted on Thu, 23 Nov 2023 19:00:00 +0000

In 1991, physicists spotted a cosmic ray with so much energy it warranted an ‘OMG.’ Now that energetic particle has a new companion.

Creator: Emily Conover

Guid: https://www.sciencenews.org/?p=3133406

The “Oh-My-God” particle has a new companion.

In 1991, physicists spotted a particle from space that crashed into Earth with so much energy that it warranted an “OMG!” With 320 quintillion electron volts, or exaelectron volts, it had the kinetic energy of a baseball zipping along at about 100 kilometers per hour.

Now, a new particle of comparable energy has been found, researchers report in the Nov. 24 Science. Detected in 2021 by the Telescope Array experiment near Delta, Utah, the particle had an energy of about 240 exaelectron volts. And mysteriously, scientists are unable to pinpoint any cosmic source for the particle.

“It’s a huge, huge amount of energy but in a tiny, tiny, tiny object,” says astroparticle physicist John Matthews of the University of Utah in Salt Lake City, co-spokesperson of the Telescope Array collaboration.

Cosmic rays consist of protons and atomic nuclei that zip through space at a wide range of energies. Particles with energies over 100 exaelectron volts are exceedingly rare: On average, scientists estimate, one such particle falls on a square kilometer of Earth’s surface each century. And particles over 200 exaelectron volts are even rarer — only a few such particles have previously been detected.

When a cosmic ray hits Earth, it collides with a nucleus of an atom in the atmosphere, creating a cascade of other particles that can be detected on Earth’s surface.

To catch the rarest, highest-energy particles, scientists build giant arrays of detectors. The Telescope Array monitors an area of 700 square kilometers using more than 500 detectors made of plastic scintillator, material that emits light when hit by a charged particle. Additional detectors measure ultraviolet light produced in the sky by the shower of particles (although those detectors weren’t operating during the newly reported particle’s arrival). Based on the times that individual scintillator detectors were hit by the cascade of particles, scientists can determine the direction of the incoming cosmic ray and use that information to trace it back to its origins.

Extremely high-energy cosmic rays come from outside the Milky Way, but their exact sources are unknown (SN: 9/21/17). Most scientists think they are accelerated in violent cosmic environments, such as the jets of radiation that blast out of the areas around certain supermassive black holes, or starburst galaxies that form stars at a frenetic pace. 

Whatever their origins, the particles must come from the relatively nearby cosmic neighborhood. That’s because the highest-energy cosmic rays lose energy as they travel, by interacting with the cosmic microwave background, the afterglow of the Big Bang (SN: 7/24/18).

Tracing back the particle’s location is complicated. “The issue is that when you detect a high-energy cosmic ray at Earth, the arrival direction that you get will not point to the source because it will be deflected by … any magnetic field that would be in the way,” says Telescope Array collaborator Noémie Globus, an astroparticle physicist at the University of California, Santa Cruz and the RIKEN research institute in Japan.  

The magnetic fields present in the Milky Way and its environs scatter the cosmic rays like fog scatters light. To trace the particle to its home, scientists must take that scattering into account. But that backtracking pinpointed a cosmic void, a region of space with few galaxies at all, much less ones with violent processes going on. 

That makes this particle particularly interesting, says astrophysicist Vasiliki Pavlidou of the University of Crete in Heraklion, Greece. “It’s actually pointing towards nothing at all, absolutely in the middle of nowhere.”

That might hint that scientist are missing something. For example, researchers may need to better understand the magnetic fields of the galaxy, says Pavlidou, who was not involved with the research. 

“Every time you have one of these very high-energy events, just because they are so rare, it’s a big deal.”

These bats are the only mammals known to mate more like birds
Posted on Wed, 22 Nov 2023 14:00:00 +0000

Male serotine bats have penises too large for penetration. To mate, the animals rub their genitals against each other, somewhat like birds’ cloacal kiss.

Creator: Darren Incorvaia

Guid: https://www.sciencenews.org/?p=3133396

As the only mammals that can fly, bats are the oddballs of the mammalian world. But serotine bats stand out for another, glaringly obvious reason — when erect, a male’s penis can swell to almost a quarter of its body length. How these bats use their humongous genitals to mate — without penetration — is a method never seen in a mammal before, researchers report in the Nov. 20 Current Biology.

At more than 16 millimeters when erect, the penis of male serotine bats (Eptesicus serotinus) has no chance of fitting inside the female’s approximately 2-millimeter-long vagina, a discrepancy that prompted biologist Nicolas Fasel to wonder how these bats go about getting it on. Videos collected at the Ukrainian Bat Rehabilitation Center in Kharkiv from 2018 to 2021 and the attic of St. Matthias Church in Castenray, Netherlands, from 2016 to 2022 revealed the answer. With footage, taken from underneath the bats, “we could see actually what was happening,” says Fasel of the University of Lausanne in Switzerland.

Instead of inserting its penis into the vagina, a male uses it to move aside a membrane covering the female’s genitals and then presses the penis against the female’s vulva and holds it there, often for just under an hour. In one observation, the behavior lasted more than 12 hours.

Once the deed was done, the fur around the female’s vulva appeared wet, which Fasel and colleagues suspect is due to semen. Other scientists told Fasel the wet spots look similar to those in which they’ve found semen after mating in other bat species, he says. These observations suggest the serotine bats are mating without penetration, a common practice in birds but one never observed in a mammal before (SN: 1/16/09).

“I think it’s super interesting because it sort of brings up a different function for a penis” aside from penetration, says Patricia Brennan, an evolutionary biologist at Mount Holyoke College in South Hadley, Mass. “It doesn’t surprise me that this is a bat because bats have some of the craziest reproductive strategies in mammals,” such as females being able to store sperm for six months or males having spines on their penises.

Fasel agrees. Among mammals, bats “just have to be the weirdos of the group.”

A brain-monitoring device may one day take the guesswork out of anesthesia
Posted on Wed, 22 Nov 2023 12:00:00 +0000

The automated device pairing brain activity and dosing kept two macaques sedated for 125 minutes, raising hopes of precision anesthesia for people.

Creator: Erin Garcia de Jesús

Guid: https://www.sciencenews.org/?p=3133184

A new brain-monitoring device aims to be the Goldilocks of anesthesia delivery, dispensing drugs in just the right dose.   

No physician wants a patient to wake up during surgery — nor do patients. So anesthesiologists often give more drug than necessary to keep patients sedated during medical procedures or while on lifesaving machines like ventilators.

But anesthetics can sometimes be harmful when given in excess, says David Mintz, an anesthesiologist at Johns Hopkins University. For instance, elderly people with cognitive conditions like dementia or age-related cognitive decline may be at higher risk of post-surgical confusion. Studies also hint that long periods of use in young children might cause behavioral problems. “The less we give of them, the better,” Mintz says.

An automated anesthesia delivery system could help doctors find the right drug dose. The new device monitored rhesus macaques’ brain activity and supplied a common anesthetic called propofol in doses that were automatically adjusted every 20 seconds. Fluctuating doses ensured the animals received just enough drug — not too much or too little — to stay sedated for 125 minutes, researchers reported October 31 in PNAS Nexus. The study is a step toward devising and testing a system that would work for people.

Normally, an anesthetic dose is based on body measurements like weight and age. But that calculation is not a perfect science. There is no clear relationship between dose and likelihood that patients will be fully anesthetized with propofol and similar drugs, says Mintz, who was not involved with the new study. So anesthesiologists give amounts on the higher end of the spectrum to ensure their patients remain unconscious.

It’s not acceptable for doctors to work with doses that aren’t necessarily going to work for everyone, Mintz says. “You’re shooting for the 99th percentile… like 99.999” percent of patients should not wake up.

While patients are under anesthesia, physicians keep a close eye on indirect markers of consciousness such as breathing rate and heart rate. Anesthetics like propofol also alter brain waves, so tracking brain activity can help anesthesiologists keep tabs on patient awareness, says neuroscientist and anesthesiologist Emery Brown (SN: 5/6/11). In practice, however, few physicians are trained to do so.

Brown and colleagues developed a device to do that work for anesthesiologists. The system requires limited human input, combining brain-monitoring medical equipment with a computer that uses algorithms to determine how the body processes propofol. Every 20 seconds, the machine calculates how much drug is needed to maintain a preset level of brain activity that previous work has shown is indicative of unconsciousness in macaques.

After computer simulations suggested the model would work, the team completed nine trials with two macaques. The researchers first manually administered the anesthetic for half an hour. Then they let the automated delivery system take over for 125 minutes. In all nine experiments, the system accurately shifted the macaques between a lighter sedation and a deeper sleep, each lasting 40 or 45 minutes.

The system isn’t the first of its kind to be developed. Some existing devices — which are not approved for use in the United States — can distribute a single, predetermined amount of drug. But because the new Goldilocks version relies on feedback from the brain, it’s a bit like flying a plane on autopilot, says Brown, of MIT, Massachusetts General Hospital and Harvard Medical School. Just as autopilot is key for helping pilots navigate long flights, using a brain-monitoring machine to automatically adjust anesthesia doses would help during long surgeries and most likely reduce patients’ post-surgery delirium.

“Doesn’t mean the pilot can decide to take the day off,” Mintz says. But because machines don’t get sleepy or need a bathroom break, the new device “is a very helpful tool … because it complements human weakness.”  

Next steps include repeating the experiments with more animals to refine the system and make the brain monitoring steps less invasive. The device from the study measured brain activity from electrodes that had been directly implanted in the monkeys’ brains, Brown says, but the goal is to switch to using EEG electrodes that attach to the scalp.

Consciousness is difficult to define, and even EEGs aren’t a perfect tool, Mintz says. People with brain diseases, for instance, may have EEGs that look slightly different than people with healthy brains. Still, blending technology with anesthesiologists’ watchful eyes can take the guesswork out of hitting the sweet spot that slips people into oblivion.

The first embryos from a mammal have now been grown in space
Posted on Tue, 21 Nov 2023 17:00:00 +0000

Mouse embryos in space can develop into clusters of cells called blastocysts. The result is a step toward understanding how human embryos will fare.

Creator: Saima S. Iqbal

Guid: https://www.sciencenews.org/?p=3133335

Mouse embryos can make it to an early stage of development in space.

In an experiment conducted in 2021, a few hundred frozen two-cell embryos from mice thawed and grew over four days on the International Space Station. Of the several dozen embryos that made it back to Earth, nearly a quarter formed healthy clusters of cells known as blastocysts.

The finding suggests that the radiation and weightlessness of space might not pose immediate obstacles to mammalian reproduction, researchers report October 27 in iScience.

The new study isolates only one part of the complicated process of reproduction and development. A blastocyst typically forms after fertilization and implants in the uterus before developing into the placenta and fetus.

But the result provides a starting point for biologists, says Christiane Hahn, a space biologist at the European Space Research and Technology Centre in Noordwijk, Netherlands, who wasn’t involved in the research. Mouse embryos are the first mammal embryos that researchers have grown in space, an important step in understanding how space affects human reproduction. Other experiments have involved animals such as salamanders, rice fish and quail. 

Previous research suggested that the conditions in space are particularly harmful to the early stages of reproduction in mice. When in space, the animals have been too stressed to mate, and studies of the rodents’ eggs showed that they accumulated several mutations due to the heavy radiation. Freeze-dried mouse sperm, however, did remain viable after one six-year stint on the space station (SN: 6/11/21).

To overcome these challenges, biologist Teruhiko Wakayama and colleagues launched two-cell embryos to the ISS. A device specially made for the experiment held the fragile, developing cells. After the experiment ended, the cells were then sent back to Earth for analysis. Out of 360 samples, 72 survived the trip, and 17 of those developed into normal blastocysts. The undamaged cells successfully multiplied and took on new identities as either precursors of fetal tissue or the placenta.

Future alterations to the procedure could potentially increase the success rate, says Wakayama, of the University of Yamanashi in Kofu, Japan. The absence of perfectly sterile conditions in the space experiment probably exacerbated cell death, he says.

Blastocysts cannot survive for long outside of uteruses, so the experiment was designed to last only a few days. It’s unclear how the cells would fare as development unfolds. In future experiments, the team would like to implant any viable embryonic cells from space experiments in mice to find out.

The researchers are especially interested in further testing the impact of microgravity on the positioning of different cells in a blastocyst. The cells that give rise to the fetus usually all sink to the bottom of the cluster, encased by cells that will become placenta. Were the fetal cells to split into two spots instead, they’d create identical twin mice. Were they to split into more, the blastocysts would probably become unviable.

In the new study, three-quarters of the fetal precursors appeared to settle in the right location. But more research is needed to fully understand the effect of microgravity on the developing cells.

Why the Thanksgiving myth persists, according to science
Posted on Tue, 21 Nov 2023 15:00:00 +0000

The science of collective memory — and a desire for clear origin stories — may explain the endurance of the Thanksgiving myth despite a messier reality.

Creator: Sujata Gupta

Guid: https://www.sciencenews.org/?p=3133361

Ask someone in the United States to name five events important to the country’s foundation and there’s a good chance they’ll mention the Pilgrims.

That’s what researchers found a few years ago when they put that question to some 2,000 people. The Revolutionary War, Declaration of Independence, Christopher Columbus’ “discovery” of the Americas and the Civil War topped the list. But coming in seventh place were the Pilgrims, the team reported in 2022 in Memory Studies.

Their inclusion in the list is bizarre, says coauthor Abram Van Engen, an English professor at Washington University in St. Louis interested in national origin stories. “There’s no great reason why we start America with the Pilgrims…. They’re kind of late to the game.”

Before them, after all, came the Native Americans, Spanish settlers in St. Augustine, Fla., and European settlers — and the slaves they brought with them — in Jamestown, Va. But the Pilgrims’ tale of religious persecution, perseverance and self-governance provides people with a tidy, if aggrandized, national origin story, says Van Engen.

The “Thanksgiving myth” is part of that tale, says coauthor and cognitive psychologist Henry Roediger, also at Washington University. The shorthand for that story, he says, goes like this: In 1621, the Pilgrims and Native Americans “had this peaceful meal and powwow [while] singing kumbaya.”

The two groups did engage in a peaceful harvest celebration in the fall of 1621, history suggests. But historians are quick to point out that the tidy tale ignores context, particularly the deadly diseases and bloody wars that devastated Indigenous populations both before and after the occasion.

Despite persistent efforts to flesh out the historical record, the kumbaya vision persists. That’s because history and memory, far from being interchangeable as commonly assumed, often exist in opposition. History is rooted in fact, while memory is rooted in story. When shared across individuals, those stories — with their half-truths, exaggerations and elisions — foster unity.

Origin stories like the Thanksgiving one are particularly sticky as they underpin a group’s raison d’être. Fixing or changing the story risks muddying the plot and tearing apart the group, says Van Engen. “The Pilgrims just become right for telling [the] stories … that we want to tell about ourselves.”

Mythological origin stories are not unique to the United States. “Each nation has its heroic story. That is the tradition of collective memory,” says Chana Teeger, a sociologist at the London School of Economics and Political Science who studies how South Africans teach about apartheid.

But scholars are starting to grapple with how nations should contend with difficult pasts. “How do you keep a strong national identity and patriotism while at the same time acknowledging the more negative aspects of your history?” Roediger asks. The answer, as evidenced by increasing calls for racial reckonings in the United States and elsewhere, is very much a work in progress.

Thanksgiving has become a “mental habit”

Stories, Aristotle observed some 2,400 years ago, contain a distinct beginning, middle and end strung together via a causal chain, or plot.

Our brains are wired for such stories, psychologists discovered much later. People rely on clear narratives to avoid information overload, anthropologist James Wertsch and psychologist Olivia Jäggi, both of Washington University, reported in 2022. Our story-minded brains turn us into “cognitive misers,” they wrote in Progress in Brain Research. The pared-down nature of stories, in other words, is much easier for us to remember than the complex, often ugly, arcs of history.

For that 1621 Thanksgiving, the complex historic arc goes like this. Up to 90 percent of the Wampanoag population had died from an epidemic brought by a previous wave of European explorers by the time the Pilgrims arrived in December 1620 in what’s now Massachusetts. The weakened community faced threats from an encroaching neighboring tribe. Meanwhile, the Pilgrims, unaccustomed to the new environment and climate, were dying of starvation and disease.

In March 1621, those struggling groups formed an alliance. The Wampanoag people could teach the Pilgrims how to harvest crops and the Pilgrims could protect the Wampanoag people from invaders. The peace did not last. Over the next several decades, the settlers’ population exploded and European leaders displaced the Wampanoag community, often through dishonest or violent means. War broke out in 1675, killing hundreds of colonists and thousands of Native Americans. Settlers killed the Wampanoag leader and displayed his head on a spike for two decades. 

“The common narrative makes the settlers look like the good guys. Once you start chipping away at it, then everything falls apart,” says social studies educator John Bickford of Eastern Illinois University in Charleston.

History and memory have different relationships to the past, Wertsch explains. Historians will sacrifice narrative to preserve the facts. Agents of collective memory, such as political leaders, museum curators, teachers and family members, will sacrifice the facts to preserve the narrative — and group solidarity.

Consequently, memory and history are often at loggerheads, wrote French historian Pierre Nora in the 1989 Representations. “Memory and history, far from being synonymous, appear now to be in fundamental opposition.”

Moreover, the narrative habits offered up by memorable, though potentially fictitious, stories are just as hard to break as other habits, such as stopping nail-biting or forgoing that daily cup of coffee. For instance, we hear the word “bread” and we think “butter.” We hear “Thanksgiving” and we think Pilgrims and Native Americans singing kumbaya.  

The Thanksgiving myth came together slowly

But in fact, adding Pilgrims to the Thanksgiving narrative is a surprisingly recent affair, beginning some 200 years after their arrival in New England.

Thanksgiving was initially an altogether more informal affair. European settlers celebrated thanksgivings, or harvest festivals, even before the Pilgrims’ arrival. And the Pilgrims themselves were somewhat sporadic with their feasts, celebrating the day when new friends or supplies arrived from Europe or when they defeated the Native Americans in various wars. In 1789, Thanksgiving wasn’t a national holiday but George Washington issued a proclamation celebrating the day in the name of an “Almighty God.”

In the 1820s, when the United States was roughly 50 years old, things started to formalize. Research into nation building shows that the half-century point is about when official histories, such as those in textbooks, begin to appear, Van Engen says. Such histories typically double as memory projects (SN: 4/12/22).

In the United States, those projects began at a time when the young nation was shifting from an agrarian to an industrial society. As people moved away from their birthplaces for work, kinship ties were weakening. Starting in 1827, Sarah Josepha Hale, author and editor of a prominent women’s magazine, began calling for an official and family-oriented Thanksgiving holiday to bring families back together. Nearly four decades later in 1863, with the country in the midst of the Civil War, President Abraham Lincoln took heed and turned Thanksgiving into a national holiday to promote unity.

From that point, presidents — powerful players in building a nation’s collective memory, and the accompanying feelings of national pride — began issuing annual Thanksgiving proclamations, says political scientist Judd Birdsall. Birdsall, of Georgetown University in Washington, D.C., has read every one of those speeches to see how those memories evolve and coalesce over time to eventually capture the modern-day Thanksgiving spirit. “It’s a very niche specialty,” Birdsall admits.

Theodore Roosevelt made the earliest vague reference to “the first settlers” in his 1905 proclamation, by noting their many hardships, Birdsall reported in 2021 in the Review of Faith & International Affairs. Franklin Delano Roosevelt identified the Pilgrims by name in 1939. But only after World War II do Pilgrims come to regularly feature in these proclamations, morphing into “archetypical Americans,” Birdsall says.

Those speeches also show how America’s founders and political leaders have typically either ignored Native Americans or treated them as supporting actors to the main story. Their first appearance in the Thanksgiving story is in 1908, with Teddy Roosevelt’s pejorative mention of an “Indian haunted wilderness.” In 1980, President Jimmy Carter obliquely referenced the Native Americans by calling Thanksgiving “a commemoration of the day America’s earliest inhabitants sat down to a table with European colonists.” Ronald Reagan made Native Americans more central to the story, noting in 1986: “Indeed, the Native American Thanksgivings antedated those of the new Americans.”  

America’s origin story is still in its messy middle

Breaking up with the Thanksgiving narrative is no easy feat. But some people in the United States are starting to question Thanksgiving and other stories pointing to the country’s rosy beginnings, Wertsch says. “How do you [begin to] break a bad habit? You have somebody point it out to you.”

That’s what happened, say Wertsch and others, when a group of journalists at the New York Times launched the 1619 Project a few years ago. Led by journalist Nikole Hannah-Jones, that long-term endeavor began the U.S. story with slaves’ arrival in Virginia in August 1619. The nation’s story, they argued, spirals outward from that ugly point.

“If there’s anything that debunks our national origins, it’s the 1619 Project,” Bickford says.

Today, that project has come to frame many of the country’s ongoing culture wars, especially fights over how to teach history. Institutions, such as schools and museums, become places where history and national identity collide, says Teeger. “History education [is] a site where collective memories are negotiated.”

Social scientists refer to conflicts over how events ought to be remembered as “mnemonic standoffs.” In the case of Thanksgiving, the standoff is over whether Thanksgiving ought to be remembered as a day of celebration or, as a growing chorus of Indigenous people and their allies call for, a day of mourning. Such standoffs illuminate the central tension between history and collective memory, researchers say. How do people maintain unity while acknowledging their difficult pasts?

Historians and social scientists used to assume that collective memories need to be positive, even mythological, to succeed. “Forgetting, I would go even as far as to say historical error, is a crucial factor in the creation of a nation,” French philosopher and historian Ernest Renan argued in 1882.

Contemporary researchers question that view. Georgian people’s collective memories, for instance, include ideas of the Eastern European country as a perpetual underdog, says anthropologist Nutsa Batiashvili of the Free University of Tbilisi in Georgia. “The skeleton narrative, which repeats itself, is that a big enemy comes, and Georgians fight heroically, but they have traitors inside. And they lose the war but still manage to save the culture and integrity and identity.”  

Can people in the United States rewrite their national story to reflect this sort of complexity? That remains an open research question, Wertsch says. Stories work best when they have a neat beginning, middle and end. But Thanksgiving, and the broader American origin story, remain caught in the messy narrative middle. “We don’t have an ending of racism in America. It’s still here,” he says.

The more optimistic framing, Batiashvili says, is that the American story is still being written. “It’s a narrative in the making.”

Crabs left the sea not once, but several times, in their evolution
Posted on Mon, 20 Nov 2023 15:00:00 +0000

A new study is the most comprehensive analysis yet of the evolution of “true crabs.”

Creator: Amanda Heidt

Guid: https://www.sciencenews.org/?p=3133189

Most terrestrial plants and animals left the ocean a single time in their evolutionary history to live ashore. But crabs have seemingly scuttled out of the sea more than a dozen times, with at least two groups later reverting back to a marine lifestyle, a study finds.

The research, published November 6 in Systematic Biology, sheds new light on the evolutionary history of the group Brachyura, which includes roughly 7,600 species of “true crabs,” and includes the most comprehensive evolutionary tree yet created for the group. And the study offers clues about how other early invertebrates may have evolved a terrestrial lifestyle, researchers say.

Unlike for well-studied animals such as birds and mammals, a unified crab tree of life has been lacking, says Kristin Hultgren, an invertebrate zoologist at Seattle University. “While the authors have developed a useful framework for understanding the complexity of transitioning to terrestrial life, one of the most important contributions is the extensive, well-dated evolutionary tree.”

Crabs are an extremely diverse group and have colonized nearly every type of habitat on Earth. It’s been a challenge to study when crabs first shifted from one habitat to another during evolution because, like some other invertebrates, crabs don’t have the extensive fossil trail that early vertebrates do, says Joanna Wolfe, an evolutionary biologist at Harvard University.

Past research has also often treated marine, freshwater and land crabs as discrete subgroups when they’re more like a continuum, Wolfe says. “They’re not distinct and actually have a lot in common, and looking at them together helps trace their evolution.”

Wolfe and her colleagues collected genetic data from 333 species of crabs in the group Brachyura. These crustaceans are evolutionarily distinct from, although closely related to, another group of crustaceans that independently evolved crablike bodies and are often erroneously referred to as crabs, including animals like the hermit and king crabs.

The team then combined that genetic data with dozens of fossils to generate a crab evolutionary tree, layering on details about each species’ life history and adaptations for living on land to reconstruct a possible timeline of when crabs colonized drier ground.

True crabs diverged from other crustacean lineages roughly 230 million years ago during the Triassic Period, the researchers found, refining previous estimates. Over the next hundred or so million years, brachyurans diversified widely during a period previously dubbed the “Cretaceous crab revolution.”

The study also showed that during their evolution, crabs appear to have adapted to a more terrestrial lifestyle as many as 17 times, either by shifting from the ocean to the intertidal zone or similarly salty habitats like mangroves, or by colonizing freshwater estuaries and rivers on route to land. In at least two cases, crabs reverted to a marine lifestyle long after they’d left.

The amount of times that crabs independently left the ocean is “astonishing,” says Katie Davis, an evolutionary paleobiologist at the University of York in England who was not involved in the research. “And it’s really fantastic that molecular biology, fossils and modern numerical techniques can be combined to provide insight into previously unanswerable questions.”

The study also hints at what other early arthropods that ventured onto the land may have been like, Wolfe says. Past studies have shown that crabs and insects share a common, if unknown, aquatic ancestor. By looking at the types of crabs that successfully left the ocean, it’s possible to guess at what adaptations early insects might have needed to do the same. Modern crabs living out of the water today, for example, excel at keeping themselves from drying out and have limited their dependence on water for reproduction.

“If you’re going to be the first proto-insect to come out of the ocean … you’re probably going to need those kinds of adaptations,” Wolfe says.

‘Most Delicious Poison’ explores how toxins rule our world
Posted on Mon, 20 Nov 2023 13:00:00 +0000

In his debut book, Noah Whiteman tours through chemistry, evolution and world history to understand toxins and how we’ve come to use them.

Creator: Aaron Tremper

Guid: https://www.sciencenews.org/?p=3133001

Most Delicious Poison
Noah Whiteman
Little, Brown Spark, $30

After his father’s unexpected death from alcohol use disorder in 2017, evolutionary biologist Noah Whiteman undertook a journey to understand how nature’s toxins affect the world. The result is his debut book, Most Delicious Poison: The Story of Nature’s Toxins — From Spices to Vices.

The book weeds through chemistry, evolution and world history to explore the origins of toxins and how humans have co-opted them for everything from medicines to spices to pesticides. “The chemicals in these products of nature are not a sideshow — they are the main event,” Whiteman writes, “and we’ve unwittingly stolen them from a war raging all around us.”

That tussle, part of what Charles Darwin called the “war of nature,” is the innovative ways plants and animals continuously evolve traits that one-up their predators or competitors. Many of the chemicals that we stock in our cabinets and pharmacies, for instance, originated in plants as deterrents against insects snacking on them, Whiteman points out. These chemicals act on our brains and bodies thanks to the surprising neurological similarities between insects and humans.

Whiteman, who studies how insects adapt to plant toxins, is a knowledgeable tour guide through this greenhouse of poisons and cures. And it is a greenhouse. Though people put some animal-made toxins to use, the plant derivatives steal the show.

Chrysanthemums with their insecticidal compound, pyrethrin, make an appearance in the book, as do terpenoid-wafting pines, calming chamomile and morphine-like water lilies. To tame the tangle of chemicals and their interactions, Whiteman dedicates each chapter to a couple of toxin classes and lays out their source in the natural world, their chemical mechanisms and historical context for their use by people.

Take tannins. They show up in a wide array of plants, including oaks, tea plants and grapes. Whiteman muses that these chemical compounds may protect plants by inhibiting the ability of microbes and herbivores to absorb nutrients. Tannins also bind to salivary proteins, resulting in the “rough, dry puckering sensation” that many people enjoy while sipping a glass of Cabernet Sauvignon. Humans have also long put the protein-binding properties of tannins to use in tanning animal hides for leather. For nearly 1,500 years, Europe and then its colonies relied on ink manufactured from tannin-rich oak galls for drafting important documents, including the Magna Carta and the Declaration of Independence.

Perhaps the most important role of toxins in the human world can be found in our pantries and medicine cabinets. Whiteman focuses on pharmacological heavyweights such as the antimalarial drug quinine, derived from the bark of the cinchona tree, and salicylates, such as aspirin and oil of wintergreen. Curare, cocaine and scopolamine demonstrate how we’ve wrangled these alkaloids into anesthetics. It’s one of many instances where Whiteman nods to Indigenous communities around the world that have been repeatedly exploited or gone uncompensated for their medicinal discoveries.

“It is no wonder that many countries in Latin America and elsewhere in the global tropics now have biopiracy laws that strictly regulate the export of natural products,” Whiteman notes.

Whiteman closes by examining how medieval Europe’s lust for spices catapulted the world into five centuries of geopolitical upheaval. The Columbian exchange, the Opium Wars and the founding of the East India Company are all pit stops along Whiteman’s exploration of how the pursuit of all things psychoactive and medicinal fueled European colonialism. The lasting consequences, Whiteman argues, include infringement on Indigenous rights, global biodiversity loss and the climate crisis.

The opioid epidemic and alcohol use disorder also loom large in the book. Here, Whiteman’s assertion that our use of toxins “walk[s] a knife’s edge between healing and harm” is loudest. His father haunts many of the personal anecdotes sprinkled throughout the 304-page read. Whether he’s recalling the toxicology report from his father’s autopsy or noting his family’s fondness for black pepper, Whiteman explores grief as much as he does science: “My attempt to grasp why [my father] died allowed me to identify and then draw together the many ways that nature’s toxins affect the world.”

Personal and well-researched, Most Delicious Poison has wide appeal, in part, as Whiteman points out, because indulging in nature’s toxins “is an essential part of what it means to be human.” So go ahead. Pour a cup of herbal tea, add some drops of lavender oil to the diffuser and enjoy this mind-bending read.

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50 years ago, scientists suspected that lost sense of smell could be restored
Posted on Fri, 17 Nov 2023 16:00:00 +0000

Cells responsible for humans’ sense of smell can regenerate. Now, research spurred on by the pandemic could help answer questions about the process.

Creator: Aina Abell

Guid: https://www.sciencenews.org/?p=3133307

Putting smell back in the whiffer – Science News, November 17, 1973

P.P.C. Graziadei and J.F. Metcalf of Florida State University have been producing … ever more detailed, evidence for olfactory nerve regeneration in mammals…. Might olfactory nerves be regenerated in people who have trouble smelling, thereby restoring or improving their sense of smell? “The phenomena of regeneration are applicable to all vertebrates and most likely to humans,” says Graziadei.

Update

The scientists’ hunch was right on the nose: The human cells that detect scent information and send it to the brain can replenish themselves, though exactly how is unclear. Experimental therapies to help people who have lost their sense of smell due to COVID-19 could help researchers figure it out (SN: 9/24/22, p. 14). Smell training, which involves regularly and deeply smelling various scents, might rewire cells’ connections to the brain or stimulate new cell growth. Treating damaged cells with steroids and blood plasma might aid healing. More invasive treatments such as nasal lining transplants aim to boost regenerative stem cells.

Why a popular breast cancer drug may be less effective for some Africans
Posted on Fri, 17 Nov 2023 13:28:57 +0000

A genetic variant commonly found in certain African populations appears to impair tamoxifen’s ability to tackle breast cancer.

Creator: Saima S. Iqbal

Guid: https://www.sciencenews.org/?p=3133227

WASHINGTON — A genetic variant commonly found in some Africans may stymie the effects of a popular breast cancer drug.

The variant produces a sluggish version of the enzyme known to activate tamoxifen. People who inherit two copies of the variant show five times less active drug in their bloodstreams compared with people who don’t have that variant, researchers reported November 2 at the American Society of Human Genetics annual meeting. As a result, many of these patients may receive a dose that’s insufficient to treat their cancer.

The gene, called CYP2D6, that produces the crucial enzyme differs dramatically among people. On average, a fifth of Africans carry at least one copy of the variant that the researchers studied. Across the continent, however, that figure ranges from a slim 5 percent to over 34 percent.

Preemptive genetic screening that identifies patients with the genetic variant would probably cost too much for local clinics and hospitals, says molecular geneticist Comfort Kanji, who is based at the African Institute of Biomedical Science and Technology in Harare, Zimbabwe. But he imagines that his team’s findings could inspire clinical trials that test larger starting doses of tamoxifen in heavily affected groups.

Kanji and his colleagues collected daily blood samples from 42 Zimbabweans taking tamoxifen. Some of the participants had one copy of the variant, while others had two. A third group had a different version of the gene with no known effect on the enzyme. The differences in how they metabolized the medication emerged right away and remained for the duration of the 3-week-long experiment.

Additionally, simulations suggested that doubling the prescribed amount of the drug for participants with two copies of the variant would bring levels of active drug in the blood back to normal — and with few short-term consequences.

The study provides powerful results despite a small sample size, says David Twesigomwe, a pharmacogeneticist at the Sydney Brenner Institute for Molecular Bioscience in Johannesburg who was not involved in the research.

It offers a clear-cut case for metabolic screening, he says. Even as comprehensive genetic testing remains out of reach for many Africans, he believes simpler, narrower tests could do the trick, potentially laying the foundation for clinicians to incorporate screening more widely in treatment.

Each year, around 200,000 people in sub-Saharan Africa receive diagnoses of breast cancer. Roughly 40 percent survive for longer than five years past their diagnosis, unlike 86 percent in the United States. The main reason is that many patients in Africa struggle to access or afford treatment, and as a result, show up to clinics with late-stage cancers. This new finding is unlikely to turn those cases around, but it could help make timely care more effective, Kanji says.

Worldwide, about 30 percent of patients with estrogen receptor-positive breast cancer — the most common type — show little improvement on tamoxifen. That proportion is even higher among African women, Kanji says. The prevalence of the studied gene variant, or others with a similar effect, could offer a partial explanation.

A separate study would be required to see if the findings extend to African Americans, Kanji and Twesigomwe both say. In the United States, Black women are 40 percent more likely to die of breast cancer— with about 28 deaths per 100,000 for Black women compared with 20 per 100,000 for white women — despite a similar rate of diagnosis.

Experts caution that the reasons why are multifaceted, including biological, sociological and historical. The role that a variant of CYP2D6 plays may constitute a sliver of a sliver.

The enzyme that the gene generates metabolizes more than just tamoxifen. It’s responsible for breaking down many other drugs, including opioids, beta-blockers and a common class of antidepressant drugs called selective serotonin reuptake inhibitors. That means that people with different variants of the gene may respond better or worse to those medications too.

Bonobos, like humans, cooperate with unrelated members of other groups
Posted on Thu, 16 Nov 2023 19:08:36 +0000

Cooperation between unrelated individuals in different groups without clear and immediate benefit was thought to be uniquely human. Its presence in bonobos may help explain its evolution.

Creator: Jake Buehler

Guid: https://www.sciencenews.org/?p=3133298

Humans regularly cooperate and share resources with other, unrelated humans in different social groups, often without any immediate, reciprocated benefits. The phenomenon has been considered unique to our species. But some bonobos appear to share this social trait, a study finds.

This type of cooperation is thought to underpin human civilization. So bonobos’ ability to bond and cooperate with groups of nonrelatives across group boundaries, even when there’s no immediate payoff, may provide some insight into the kinds of evolutionary conditions that led to the development of humankind’s large-scale societies, researchers report November 16 in Science.  

Both chimpanzees (Pan troglodytes) and bonobos (P. paniscus) live in social groups with individuals that may not be very closely related. But compared with territorial and aggressive chimpanzees, bonobos have a more easygoing, tolerant attitude toward other groups. Bonobos occasionally groom and share food with unrelated individuals from other social groups and have even been known to adopt outsiders’ young (SN: 3/18/21). But the extent of the apes’ cooperative behavior has been unclear.

So behavioral ecologists Liran Samuni of the German Primate Center in Göttingen and Martin Surbeck of Harvard University studied two bonobo groups in the Congo’s Kokolopori Bonobo Reserve. Over two years, the team recorded which bonobos exchanged grooming services and shared food, and when.

Conflict and competition are not completely absent among bonobos. So the researchers also recorded when the apes formed alliances with members of the other group, cooperating to attack a third individual.

The two groups encountered each other frequently. They interacted with each other nearly 100 times over the study, sharing 20 percent of the two-year observation period in each other’s company. Some meetings lasted for just an hour, others for multiple weeks, allowing for longer-term bonds to be forged.

While the bonobos were together, the researchers documented many instances of cooperative behavior. Of the more than 3,700 grooming interactions observed, 10 percent were between bonobos of different social groups. Of all partnerships formed to attack a third individual, 15 percent were between bonobos of different groups.

“This is not a one-off kind of thing,” Samuni says, where individuals share food very occasionally, for example. In the Kokolopori bonobos, 6 percent of all food shares were across groups.

The cooperation wasn’t random. Individuals that tended to engage in cooperative behavior within their group were more likely to interact with bonobos in the other group that had the same tendency. This cooperation doesn’t appear to be solely motivated by immediate reciprocation, the researchers say. For instance, during the study, only 14 percent of bonobos that shared food with a partner in the other group had the deed reciprocated.  

The study’s overall findings build on evidence from bonobos in captivity behaving similarly and raises the possibility that cooperating with nonrelatives across social groups is intrinsic to the species. Many animals will aid and cooperate with relatives, since such behavior encourages the survival and proliferation of one’s own genes, albeit indirectly. When helping nonrelatives, the evolutionary benefit is even more indirect, and doesn’t evolve as readily.

Bonobos aren’t the only nonhuman animals known to behave in this way. Male dolphins will cooperate with other unrelated males to guard females, which increases their own chances of mating. But, unlike with a lot of the bonobo cooperation observed in the new study, there’s a clear, self-directed benefit involved in the dolphins’ behavior. 

Food sharing between unrelated individuals, though, is rare, Samuni says. Vampire bats, bonobos and humans are among the few species known to do it. Chimps also do this, but share food only within the social group, Surbeck says. In human evolution, such sharing “is considered one of those behaviors that supported our societies, that allowed us to sustain each other in terms of food shortfalls,” Samuni says.

Our own species’s behavior is what makes the new result particularly interesting, says Shinya Yamamoto, a comparative cognitive psychologist at Kyoto University in Japan.

“Humans sometimes compete or fight with neighboring groups, but other times we cooperate even with outgroup members,” Yamamoto says. Among our primate relatives, it’s been easier to find examples of aggression and competitiveness, especially in humans’ close relatives, chimpanzees. But the evolutionary origins of humankind’s cooperative side remain unclear.

Humans are equally related to chimpanzees and bonobos, and the new research doesn’t tell us whether early human ancestors were more like chimps with their universally rigid territories and lethal patrol groups, or like the more relaxed bonobos (SN: 9/17/14). But the finding could lead to insights into the types of conditions in which either side of the coin evolves, Surbeck says.

“Under which circumstances do you see this cooperation? Under which circumstances do you see more of a chimpanzee pattern, in permanently hostile relationships between groups?” he asks. “What shifts the needle from one to the other?”

The finding also suggests that extensive, long-term cooperation between groups can occur without the heavy influence of cultural factors and social norms. In humans, these have been considered necessary to build and sustain between-group cooperation, Samuni says.

“We are showing quite a simple system,” she says. “And we still see it emerging and in a way that is quite similar [to humans].”

There could still be a cultural component at play with these two bonobo groups, Yamamoto says. It’s possible that over generations, some bonobos have learned to be particularly social, similarly to how elements of human culture form.

This study looked at just two wild bonobo groups, and other bonobo groups are known to have variable rates of interaction with other groups, Yamamoto says. So studying more of the apes might reveal something akin to social norms.

Flint grapples with the mental health fallout from the water disaster
Posted on Thu, 16 Nov 2023 13:00:00 +0000

The water crisis started almost a decade ago. Residents of Flint, Mich., are still healing from the disaster — and caring for their own.

Creator: Aimee Cunningham

Guid: https://www.sciencenews.org/?p=3132950

On a Saturday in May in Flint, Mich., residents took seats in one of three rings of chairs at a local food bank. The 50 or so participants, spanning three generations, would spend time that morning sharing stories and practicing deep listening as part of a healing circle. It’s one component of a wider community-based movement to build relationships and challenge racist beliefs and systems.

In one circle, healing practitioner Todd Womack asked participants to introduce themselves and describe their favorite desserts. Fingers snapped softly to signal mutual enjoyment. Next, participants paired off, with instructions to take turns asking about something that recently made them smile or laugh — and to listen without interruption. From there, new pairs moved to other topics, such as an accomplishment they were proud of.

Healing circles are a space to foster community, says Lynn Williams, the director of equity and community engagement at the Community Foundation of Greater Flint, who helped organize the event that morning. The circles allow room for “healing of trauma from systems, from oppression, from negativity,” she says. And they provide a place to tell a community’s full story, to “highlight the assets and the cultural contributions.”

The circles are one way to let people know they matter when society keeps telling them they don’t.

The residents of Flint — a city with a majority Black population and many people experiencing poverty — know this disregard well. In April 2014, to cut costs, state officials switched the city’s water source from Lake Huron to the Flint River without an adequate treatment plan. The public health catastrophe that has followed “is a story of government failure, intransigence, unpreparedness, delay, inaction and environmental injustice,” according to the final report from the Flint Water Advisory Task Force, commissioned to find the causes of the water disaster. The human-made crisis turned a necessity into a hazard for the residents of the city, which had a population of around 99,000 at the time. The lack of proper treatment exposed people to bacteria, excessive disinfection chemicals and lead.

Residents reported that their physical health suffered. People broke out in rashes, lost hair and had gastrointestinal illnesses. Researchers found an association between a local, deadly Legionnaires’ disease outbreak in 2014–15 and insufficient disinfection in the water system. Many children have developed health and behavioral problems from lead poisoning. “I am so upset,” says Bishop Bernadel Jefferson of Faith Deliverance Center in Flint, speaking of her grandson’s lead exposure and subsequent learning difficulties. “The system failed him.”

Mental health has suffered, too. Residents have reported experiencing depression, anxiety and post-traumatic stress disorder. With disasters, especially those that involve toxic exposures, “the emotional consequences are long-term, because they’re fueled by this concern [that] health or cognitive functioning has been forever adversely affected,” says Evelyn Bromet, a psychiatric epidemiologist at the Renaissance School of Medicine at Stony Brook University in New York who has studied the Chernobyl nuclear power plant disaster.

For a year and a half, officials dismissed residents’ concerns about the safety of the water. “It was horrifying, because not only were they not believed, but they weren’t taken seriously,” Bromet says. The anger that goes along with that “is of course a detrimental emotional state to be in for a long period of time.”

Other difficult experiences compounded the anguish that came with the water disaster. “This community has been exposed to multiple traumas,” says Womack, a social worker at the University of Michigan–Flint. When the disaster began, Flint was still struggling with the loss of tens of thousands of jobs due to General Motors’ layoffs and plant closures from the 1970s to the 1990s. The COVID-19 pandemic began as the water disaster continued.

Mental health remains a pressing concern for the community. But there aren’t enough mental health providers to meet the need, says Barbara Wolf, a clinical health psychologist at McLaren Health Care in Flint. Genesee County, which includes Flint, is among the areas in the United States with a shortage of mental health professionals, according to the U.S. Department of Health and Human Services.

So, as they’ve done before, Flint residents are finding a way. It was the community’s organizing and activism that brought attention to the water disaster. And as Flint approaches 10 years since the disaster began, local organizations continue to help the community heal. There are mental health and resiliency trainings, mindfulness meditation and community conversations about mental health. “There’s not just one approach,” says Kristin Stevenson, project manager for the Flint Resiliency in Communities After Stress and Trauma, or ReCAST, program at the Greater Flint Health Coalition, and a healing practitioner. “All of these things combined are what create the impact.”

What has happened in Flint — and what continues there — illustrates a community’s activism and perseverance, as well as the mental health fallout of a disaster. But this story won’t end in Flint. Communities across the country could find themselves part of the next chapter, their lives upended by catastrophe. The United States’ aging water infrastructure has led to other water crises and could trigger more. Wildfires, hurricanes and floods, fueled by climate change and other human-caused environmental changes, are increasing in frequency and destructiveness. Mental health will suffer in the aftermath of these traumatic events. The water disaster in Flint can be seen as both a warning and a model of community response.

“We recognize that our struggle, if not now, will become yours,” Womack says.

The making of the water disaster in Flint

A decorative archway spanning one of downtown Flint’s main thoroughfares reads “Flint: Vehicle City.” The city was home to a booming carriage business before General Motors was founded there in 1908. Residents look back with pride on the community’s activism during GM workers’ famous sit-down strike for better pay and recognition of their union, the United Auto Workers. For around six weeks in 1936–37, striking workers occupied factories to stop production. Family and community members provided supplies and support from the outside. The strike heralded the rise of the labor movement in the automotive industry.

As in other cities, Flint’s industrial growth was detrimental to its river, as factories would discharge waste directly into the water. The Clean Water Act of 1972, which regulates pollution from industrial and municipal sources, has improved the health of U.S. waterways, including Flint’s. In 1974, the Safe Drinking Water Act was enacted to safeguard the country’s drinking water. The law sets standards for levels of contaminants, including microorganisms, chemicals and metals such as lead.

In 2014, Flint’s water treatment plant hadn’t been fully operational for almost 50 years. Instead, the city had been purchasing treated Lake Huron water from Detroit’s water utility. But an unelected emergency manager, placed in charge of Flint’s finances by Michigan’s then-Governor Rick Snyder, had authorized a switch to the Flint River as a cost-saving measure. Water treatment is a complex process, and the Flint River water was more corrosive than other water sources. But the Flint plant didn’t test its treatment procedures sufficiently, according to an analysis by water treatment experts. In violation of federal requirements, there was no corrosion control treatment, which helps prevent lead from leaching into the water as it moves through the distribution system’s pipes.

When residents turned on their faucets in the weeks after the switch on April 25, they were unsettled by what came out. “I used to love tap water, just to run it and let it get cold,” Jefferson says. But after the switch, the water left a film in her mouth. Flint resident Gina Luster liked to chew ice, but it started to taste “like metal, like I’m chewing steel.” Cynthia Watkins, apostle at the Well International Church Ministries in Flint, remembers the water “just smelling, it was horrible.” For Roshanda Womack, a professional storyteller and spouse of Todd Womack, the water had a strong odor and was sometimes cloudy or had a slight brown tinge to it.

People in the community spoke out about the poor water quality, with some reporting rashes from exposure to the water. But officials maintained that the water was safe for use.

Warning signs mounted in the following months. The water in the distribution system tested positive in August for E. coli, which can indicate fecal contamination and inadequate disinfection. This prompted a boil water advisory. In October, General Motors announced that it would stop using the city’s water at an engine plant over concerns about corrosion. While the company switched to a different water supply for manufacturing, officials still claimed Flint’s water met safety standards for people. Throughout 2014, church leaders and other community members worked to elevate people’s concerns about the water.

At the end of 2014, the city was served with a Safe Drinking Water Act violation, having exceeded allowable levels of trihalomethanes, disinfection by-products tied to an increased risk of cancer. These chemicals form when disinfectant added during treatment reacts with naturally occurring materials in river and lake water. One of the challenges of water treatment is maintaining proper disinfection while limiting by-product chemicals.

After the public notice of the violation in January 2015, Flint resident LeeAnne Walters asked the city to test her water. Samples from February and March revealed lead levels around seven and 27 times what spurs regulatory action. Walters’ home plumbing was plastic. An analysis of the city service line to the house revealed it was the source of the lead. When Walters’ 4-year-old son was tested for lead in March, his level was 6.5 micrograms per deciliter. No amount of lead is considered safe. At the time, the U.S. Centers for Disease Control and Prevention used a reference value of 5 µg/dL, developed based on national surveys, to identify kids with the highest lead levels. In 2021, the CDC lowered that reference value to 3.5 µg/dL.

As the year continued, local organizations and churches formed the Coalition for Clean Water, which passed out flyers to inform residents of the water safety issues and collected water samples for testing. People protested, with rallies in Flint, Detroit and Lansing, the state capital. In August, organizers delivered to the mayor a petition, with more than 26,000 signatures, demanding to switch back to water from the Detroit system.

Then, at a September news conference, local researchers announced an alarming rise in the percentage of Flint children with lead levels of 5 µg/dL or higher. The analysis included children younger than age 5 who had had their levels checked as part of routine lead screening — 736 children in 2013, before the water source changed, and 737 after, in 2015. The percentage of kids considered to have high lead levels increased from 2.4 percent in 2013 to 4.9 percent in 2015, the researchers reported in 2016 in the American Journal of Public Health. In neighborhoods with the most lead in the water, the jump was from 4.0 to 10.6 percent. A similar change was not seen in 2,202 children who lived outside of the city and had a different water source.

Lead harms children’s developing brains and nervous systems. Studies have found that the metal disrupts communication between nerve cells and impairs the hippocampus, a brain region important in learning and memory. Children exposed to lead can develop learning disabilities, speech and hearing disorders, and behavioral problems. The damage can shape the rest of their lives.

Officials ultimately couldn’t brush aside the evidence of poisoned children. The city reconnected to the Detroit water system on October 16, 2015. But that water still had to flow through Flint’s pipes, which had become corroded. The city has been replacing its lead service lines but has repeatedly missed court-ordered deadlines and still isn’t finished. Lead levels have been in compliance with federal regulations since 2016 but have fluctuated recently. In 2022, lead levels rose to the highest seen in six years.

“We’re still not fixed,” says Kent Key, a health disparities researcher at the Flint campus of Michigan State University’s College of Human Medicine.

The Flint Water Advisory Task Force reported that the state government was primarily responsible for the water disaster.

The anguish Flint residents have felt

The Flint community organized, rallied and distributed testing kits and bottled water while people there lived through a disaster. “The water disaster was a traumatic experience,” Todd Womack says. “At the time, I don’t think people were saying it was traumatic. I think they were saying, ‘How do we get this basic need?’”

Eventually, the trauma rose to the surface. There had been so much worry, stress, anger and grief. Parents who had cajoled their kids to choose water over soda and juice were distraught. “I feel so guilty now,” Luster says. “I was poisoning my kid.” Pets died unexpectedly, which seemed to be tied to drinking the water. “I ended up losing both my dogs,” Watkins says. “That was just devastating.” Getting enough bottled water was a financial hardship for many. “I watched people, low-income families or on a fixed income … take half of their money to buy water every month,” Jefferson says.

And for so long, residents were told, “ ‘You’re paranoid, you’re crazy, the water is fine,’ ” Roshanda Womack says, “when you can see it’s not fine.” Jennifer Carrera, an environmental sociologist at Michigan State University in East Lansing, says there were “so many ways in which the treatment of the residents minimized their experiences…. Gaslighting is a very fair way of characterizing what happened to Flint residents.”

Yet General Motors got a different water supply for its plant. “For parts, for automobile parts,” Jefferson says, but not for people. “It was all right for us to be poisoned. It was all right to be sick. It was all right to die.”

Dionna Brown, a sociology graduate student at Wayne State University in Detroit, grew up in Flint and was a teenager during the water disaster. Brown felt “like the government is trying to poison a Black city.” She realized, “Black children, we can’t have a childhood. We have to grow up fast.”

“To live with that level of betrayal,” says Bromet, the Stony Brook psychiatric epidemiologist, “of course it takes its toll.”

As does the lack of justice. “The perpetrator, in a just and fair society, is held accountable,” Key says. “In the Flint water crisis, that still hasn’t happened.” The city has been “forced to work with the perpetrator, the state, to work towards recovery.”

The experience has left many unconvinced that the city’s water is safe. “I think you’re just going to have a large portion of the population that is never going to drink the water again,” says social epidemiologist Jerel Ezell of the University of California, Berkeley, who grew up in the Flint suburbs.

Worrying about water “puts a strain on you,” says Flint resident Tyshae Brady. “I don’t want to always go over to a friend’s house and go, ‘Hey, is your water safe to drink?’ ” The unease extends beyond Flint, too. Flint church elder Sarah Bailey, who has worked on stroke prevention in the community and other projects, recalls being at a Boston restaurant with colleagues. “The waitress brings some water to the table in glasses, and I reach over and say, ‘Do you happen to have any bottled water?’ ” One of her colleagues told Bailey the water was safe. “I said, ‘For you…. The water was not safe for me.’ ”

The mental health aftermath of the water crisis

The disaster has weighed heavily on the mental health of residents, both children and adults. From December 2018 to March 2020, researchers surveyed the caregivers of 1,203 children, ages 3 to 17. The caregiver-reported rates of anxiety and depression among the children were 13 percent for anxiety and 8 percent for depression, higher than the national rates of 9 and 4 percent for that age group, the researchers reported in September in the American Journal of Public Health.

A different research team surveyed 1,970 adult residents from August 2019 to April 2020 — around that time, Flint’s total population was just over 81,000. Twenty-two percent of the respondents had experienced symptoms of depression in the past year, while 24 percent met criteria for post-traumatic stress disorder. That’s higher than the estimated past-year rates, 8 percent for depression and 5 percent for PTSD, for the U.S. population. Extending the findings to Flint’s population suggests that around 13,600 adults may have experienced depression and around 15,000 may have had PTSD, the researchers reported in 2022 in JAMA Network Open.

People who were worried the water had harmed their or their family’s health were more than twice as likely to meet the criteria for depression and about 1.7 times as likely for PTSD, compared with people without this concern.

Past tragedies, such as a serious accident, physical abuse, sexual assault or a previous environmental calamity, can increase mental health risks when disaster strikes. “Your cumulative exposure to potentially traumatic events drives a lot of the risk for either developing or maintaining PTSD or depression,” says Dean Kilpatrick, a clinical psychologist at the Medical University of South Carolina in Charleston and one of the authors of the study in adults. Kilpatrick and colleagues found that the risk of developing symptoms of depression increased by a factor of close to three, and for PTSD symptoms by a factor of 4.6, for Flint residents with past exposure to a potentially traumatic event, compared with those without.

For some, mental health issues from disasters may persist for years. Researchers followed mothers who experienced Hurricane Katrina and had incomes less than twice the federal poverty line. The women were surveyed at three points after August of 2005, when the storm hit the U.S. Gulf Coast. Although rates of post-traumatic stress symptoms declined over time among the women, 1 in 6 still had symptoms 12 years after the hurricane, researchers reported in 2019 in Social Science & Medicine. Mothers with young children who were evacuees after the Chernobyl disaster and Chernobyl cleanup workers have had long-lasting mental health consequences.

Despite the potential impacts, only 35 percent of respondents in the study in JAMA Network Open reported that they had ever been offered mental health care to attend to issues that arose from the water disaster. If offered, most people — 79 percent — took advantage.

The COVID-19 pandemic, another traumatic experience, hit the community while they were still dealing with the water disaster. In the most recent Community Health Needs Assessment for Flint and surrounding Genesee County, from 2022, 45 percent of respondents to the assessment’s resident survey indicated that they were dealing with stress, and 33 percent said they had mental health problems such as depression or anxiety.

How the community is helping and healing

Having too few mental health care practitioners is not an issue unique to Flint. Nearly 166 million people in the United States, about half the population, live in areas with a shortage of mental health professionals. The COVID-19 pandemic has only exacerbated the problem.

Treatment options did recently expand somewhat in Flint. In May, local mental health services provider Genesee Health System opened a new outpatient clinic that serves uninsured county residents. The treatment facility is funded in part by a recently passed property tax increase to support mental health in the county.

Beyond that, Flint organizations are taking community-based approaches to help residents cope. The Flint ReCAST program, supported with a grant from the federal Substance Abuse and Mental Health Services Administration, funds local organizations seeking to address trauma and stress in the community. ReCAST has supported art, music and dance programs for young people and an initiative to build mindfulness skills among the police and community members.

ReCAST also funds Genesee Health System to offer free community mental health and resiliency trainings, on topics ranging from recognizing suicidal ideation to learning about mental health and stigma to building resiliency. ReCAST and Genesee mental health professionals have teamed up for virtual conversations about mental health called Talk About It Tuesdays.

The Flint Public Health Youth Academy, which Key began developing in 2014, is a homegrown initiative to inspire Flint’s young people to pursue careers in public health. “I wanted to create a youth group that did not allow the water crisis to be a sentence of doom and gloom,” he says, but rather a jumping-off point to create the next generation of public health professionals. Among the academy’s activities is an annual summer camp that centers on a public health topic, such as environmental justice.

Looking to the future, Stevenson, the project manager for ReCAST, is interested in bringing training of mental health ambassadors to Flint. The idea is to train trusted community members to be a source of mental health information for their neighborhoods. Stevenson is also a big proponent of healing circles as a way to help people heal and build resilience.

At the close of one healing circle on that Saturday in May, Todd Womack took out a skein of moss green yarn. Womack asked the participants to be ready to share something they appreciate about themselves. Womack went first, then tossed the skein to another participant while holding on to a piece of the yarn. As each person took a turn, the skein zigzagged across the space, unwinding along the way. In the end, everyone in the circle was holding on to the web of yarn, a physical reminder of the community and connections created that morning.

That afternoon, three different groups formed to discuss changes residents would like to see in Flint. People responded on sticky notes to different questions, such as what Flint would look like without gun violence. People talked about the city’s history, GM’s layoffs and the abandoned homes that still dot many neighborhoods, the result of years of population loss. After a peak of nearly 197,000 in 1960, the latest population estimate, from 2022, is under 80,000.

The people gathered that Saturday are among those who have stayed. They are Flintstones, as residents call themselves. While brainstorming about Flint’s future, playful chants broke out between the groups, each of which had taken on a Flint-related name. “Flintstones!” one group cried. “810!” another responded, referring to the local area code. “Bedrock!” boomed the third, naming the town from the old The Flintstones cartoon.

When residents reflect on Flint, the strong sense of community comes up again and again. It’s how residents have stood up for their health and safety during a disaster, and it’s how they continue to care for each other.

“There’s really this unity and connectedness with anyone who has lived here,” Todd Womack says.

“We’re a loving city,” Dionna Brown says, “and we’re going to be OK.”

“There are amazing, deeply committed people that live here … there’s a lot of commitment, there’s a lot of passion,” Lynn Williams says. “And that’s why we stay.”

The weight loss drug Wegovy lowered heart attack risk in a large trial
Posted on Wed, 15 Nov 2023 20:30:47 +0000

Among 17,000 adults, those on semaglutide were less likely to experience nonfatal heart attacks and strokes or death due to cardiovascular disease.

Creator: Meghan Rosen

Guid: https://www.sciencenews.org/?p=3133242

PHILADELPHIA ­— At the recent American Heart Association meeting, a cavernous room full of doctors erupted into applause. Cleveland Clinic cardiologist A. Michael Lincoff had just presented the dramatic — and at times enigmatic — results of a new clinical trial on the weight loss drug semaglutide. 

The drug, sold under the brand name Wegovy, cut patients’ risk of major cardiovascular problems by 20 percent, Lincoff reported November 11. It also reduced the risk of dying — from any cause — over the roughly 40 months patients participated in the study on average.

Lincoff’s work notches yet another role for semaglutide, which doctors currently use to treat diabetes and obesity. Previous work had already uncovered a cardiovascular benefit in people with type 2 diabetes. The new study, which targeted overweight or obese patients with cardiovascular disease, is the first to show that semaglutide can help the hearts of people without diabetes too.

That’s important because it expands the number of people who could benefit from the drug, says Tiffany Powell-Wiley, a cardiologist and epidemiologist at the National Heart, Lung and Blood Institute in Bethesda, Md. In the United States alone, more than 6 million obese or overweight people have cardiovascular disease but not diabetes. Semaglutide could be a game changer for these people, says Powell-Wiley, who was not part of the new trial. Still, she and others at the meeting recognized the limitations of the study — and the limitations of the drug. 

As much as we may want a quick fix for the rising levels of obesity seen around the world, Powell-Wiley says, “it’s important to understand that this isn’t the panacea.” We still don’t know how well semaglutide works in a diverse group of people, she says. And the drug doesn’t fix the societal, environmental and social factors that lead to obesity — and its potential health consequences — in the first place.

Semaglutide reduced the risk of heart attack, stroke and death

Semaglutide is one among a family of drugs gaining popularity for treating obesity. On November 8, the U.S. Food and Drug Administration approved a new one: tirzepatide, a relative of semaglutide that goes by the brand name Zepbound. [See also: Semaglutide FAQ ]

Semaglutide, sold under the brand name Ozempic, first came on the market for treating diabetes in 2017. Since then, the drug’s slew of uses has kept growing. In 2020, the FDA OK’d it for cutting cardiovascular risk in people with diabetes and heart disease. And in 2021, treatment for obesity (with the higher dose Wegovy) joined the list.  

Lincoff’s semaglutide trial, called SELECT, included more than 17,000 people, half of whom received weekly injections of semaglutide for roughly three years; the other half got a placebo. By the end of the trial, 8 percent of the people in the placebo group had had a nonfatal stroke or heart attack or died due to cardiovascular causes. That number dropped to 6.5 percent in the semaglutide group, Lincoff reported at the meeting and online November 11 in the New England Journal of Medicine. 

The difference between the two groups may not sound like much, but “it’s a massive result,” says Amit Khera, a cardiologist at UT Southwestern Medical Center in Dallas who was not part of the trial. One can’t underestimate the importance of finding a new treatment for patients with cardiovascular disease, he says. 

The illness is “the largest source of mortality in the world,” Lincoff said at a news conference on November 10, and there’s no single therapy that can eliminate it. Instead, doctors try to chip away at it with various treatments that offer incremental benefits. 

For overweight or obese people with heart disease, Khera says, semaglutide is another tool in cardiologists’ toolkits.

Questions remain about how the drug works — and for whom

The new study results flesh out earlier news of the trial released by funder Novo Nordisk in August (SN: 8/29/23). At the time, doctors wanted to know who the drug helped, how it worked and what side effects it set off. The latest report offers answers to some questions but kicks others wide open. 

Participants on semaglutide were slightly more likely to drop out of the trial than those taking the placebo. That difference seemed to be driven by the drug’s gastrointestinal side effects, which include nausea, diarrhea and vomiting. The number of serious issues that occurred, like cancer or infection, was slightly lower in the semaglutide group.  

Though semaglutide offered clear cardiovascular benefits for patients, one mysterious aspect of the data snagged researchers’ attention. The drug’s protective effects became apparent early in the trial — well before participants had shed lots of pounds.

That’s a big deal because it suggests semaglutide may be boosting heart health directly, perhaps in addition to the typical benefits that accompany weight loss, says Caroline Apovian, an obesity medicine specialist at Harvard Medical School and Brigham and Women’s Hospital in Boston. She was not involved in the study but is on Novo Nordisk’s scientific advisory board. Lincoff said his team is “working feverishly” on analyzing the SELECT data to better understand semaglutide’s actions.

Those data include demographic and medical information on thousands of trial participants. But the trial does have one “huge limitation,” says Powell-Wiley: 84 percent of the study’s participants were white and 72 percent were men. 

Expanding the diversity of people represented in clinical trials like these is crucial, she said. It’s a point she brought up in a panel discussion after Lincoff’s talk, and one that — like the trial’s results — garnered widespread applause. In the United States, African-American, Hispanic and Indigenous people are most impacted by obesity, Powell-Wiley says, and the new trial doesn’t tell us much about how semaglutide works in those groups.

Brain scans give clues to how teens handle pandemic stress
Posted on Wed, 15 Nov 2023 12:00:00 +0000

A study that followed hundreds of teenagers during the COVID-19 pandemic may explain why some people succumb to stress while others are more resilient.

Creator: Laura Sanders

Guid: https://www.sciencenews.org/?p=3133203

WASHINGTON — Brain scans could be used to predict how teenagers’ mental health will fare during a stressful time, an analysis that spanned the COVID-19 pandemic suggests.

The findings, presented November 13 in a news briefing at the annual meeting of the Society for Neuroscience, may help explain why some people succumb to stress while others are more resilient.

For a lot of research, “the study happens, and you report on the results, and that’s about it,” says Margot Wagner, a bioengineer at the University of California, San Diego who was not involved in the new work. But this research followed hundreds of teenagers over time, a study design that “means you can intervene and help way sooner than otherwise,” Wagner says.

The pandemic was particularly tough for many teenagers, as isolation, worry and upheaval of daily routines affected them in ways that scientists are just now starting to see (SN: 1/3/23). A record number of young people are struggling with depression and anxiety, a mental health crisis that some scientists are calling “the second pandemic” (SN: 6/30/23).

While many teenagers struggled during the pandemic, others did OK. Computational neuroscientist Caterina Stamoulis of Harvard Medical School and Boston Children’s Hospital investigated why responses differed using data collected as part of the Adolescent Brain Cognitive Development, or ABCD, study. That larger study — involving scientists at 21 research sites across the United States — aims to figure out how teenagers’ brains grow over the years.

“This is the first time in history we’re looking at thousands of participants and getting these measures over time,” Wagner says. “It’s truly remarkable.”

The ABCD study, begun in 2015, was well under way when COVID hit, so researchers possessed brain scans from before the pandemic. “Without the pandemic, we would not have been able to understand the impact of a long-lasting adverse event” that deeply affected the participants’ lives, changing their interactions with their family and friends, Stamoulis says.

At the outset of the project, fMRI brain scans measured blood flow — a proxy for brain cell activity — in 1,414 teenagers, a subset of the more than 11,000 adolescents enrolled in the ABCD study. The fMRI images recorded how certain regions of the brain behave in tandem with each other, a clue that those regions work together in what neuroscientists call a brain circuit.

“Neuroimaging data is particularly useful for developing predictive models of future outcomes,” says neuroscientist and engineer Vince Calhoun of Georgia Tech, “including resilience to stress, depression and many other things.”

In May 2020, as the world shut down, researchers started surveying the teenagers in the study about how they were holding up. These surveys, sent every few months, measured aspects of mental health, stress and sadness, among other things.

Teenagers who had weaker neural connections between certain parts of the brain before the pandemic fared worse than teenagers with stronger neural connections, the team found. These brain regions included the prefrontal cortex, a brain area that gets drastically reshaped during adolescence, and the amygdala, a structure on each side of the brain that’s involved in emotions. Weaker brain connections were associated with kids having more sadness and stress during the pandemic.

Weaker and more fragile networks predicted harder times during the pandemic, Stamoulis says. But “stronger and more resilient brain networks predicted better mental health, lower stress and lower sadness.”

She and her colleagues plan to study these brain circuits as time goes on. As brains develop, they respond to experiences and environments. If those are positive, Stamoulis says, they can be “protective factors for the brain and how its circuits evolve and become wired.”

Why Huntington’s disease may take so long to develop
Posted on Tue, 14 Nov 2023 16:00:00 +0000

Repeated bits of the disease-causing gene pile up in some brain cells. New treatments could involve stopping the additions.

Creator: Tina Hesman Saey

Guid: https://www.sciencenews.org/?p=3132998

WASHINGTON — Scientists have uncovered a clue about why it takes so long for Huntington’s disease to develop. And they may have a lead on how to stop the fatal brain disease.

Huntington’s is caused by a mistakenly repeated bit of a gene called HTT. Until recently, researchers thought the number of repeats a person is born with doesn’t change, though repeats may expand when passed to future generations.

But in some brain cells, the repeats can grow over time to hundreds of copies, geneticist Bob Handsaker reported November 2 at the annual meeting of the American Society of Human Genetics. Once the number of repeats passes a certain point, the activity of thousands of other genes in the brain cells changes drastically, leading the cells to die.

These findings suggest that adding repeats to the HTT gene in vulnerable brain cells is what is driving Huntington’s disease, says Handsaker, of the Broad Institute of MIT and Harvard in Cambridge, Mass. The research also suggests that preventing the repeats from growing may stop the development of the disease.

The new work gives “serious insight into the disease mechanism,” says Russell Snell, a geneticist at the University of Auckland in New Zealand who was not involved in the work.

About 41,000 people in the United States have symptomatic Huntington’s disease, and another 200,000 are at risk of developing it. Inheriting just one copy of a repeat-riddled HTT gene produces symptoms.

Even though individuals are born with the disease-causing gene, symptoms don’t usually appear until people are in their 30s to 50s. Those symptoms include depression, mood swings, forgetfulness, balance problems, involuntary movements and slurred speech. Eventually, a person with the disease may be paralyzed and can die from complications such as pneumonia or heart failure.

In one part of the HTT gene, the DNA bases cytosine, adenine and guanine — CAG — are repeated over and over. Most people have 26 or fewer repeats, but people who have 40 or more repeats will develop Huntington’s disease. The more repeats, the earlier symptoms start.

Previously, researchers thought that long-term exposure to the toxic huntingtin protein — made from the disease-causing version of HTT — damaged and killed brain cells, much like smoking does to lung cells, Snell says (SN: 10/18/15).

In the new research, Handsaker and colleagues examined individual brain cells in donated brains from people with and without the disease. After measuring the length of the repeated genetic bit in all the cells, the researchers found a “dramatic expansion” of the repeats in brain cells called striatal projection neurons, also known as medium spiny neurons, in people with Huntington’s, Handsaker said. The extra DNA wasn’t found in other types of brain cells in people with or without the disease.

“Some cells had up to 1,000 CAG repeats,” Handsaker said. The additions “occurred only in the vulnerable cell types that are lost to” Huntington’s disease. Exactly why the repeats grow longer in those cells and not others is not yet known.

Only a few cells had such long stretches of repeats. Most spiny neurons had added more modest numbers, he said. Based on the ages of the donors when they died and on computer simulations, the researchers noticed an unusual pattern to the ever-accumulating repeats. It can take decades to go from about 40 repeats to 80, but then the process picks up steam. It takes only a few years to go from 90 repeats to 100s, Handsaker said.

It wasn’t clear at first whether additional repeats affected the brain cells. So, the researchers examined the activity of thousands of genes by charting RNA levels in the donated cells. The activity of those genes remained stable until the disease-causing version of HTT had about 150 repeats. Then, gene activity altered drastically: Thousands of genes increased activity, while thousands of others decreased.

Since precise levels of activity are needed to keep cells healthy, it’s probably this change that leads to the death of the cells within months of reaching 150. “It looks like a switch,” Snell says. “It looks like you’re OK, more or less, to 150.”

But, Handsaker said, why things are generally fine until that point and then go awry is another mystery. “We really don’t know what goes wrong at 150.”

Regardless, keeping the growth of the repeats in check may be a way to stop the disease from progressing. CAG sequences might inadvertently get added when a protein called MSH3, which is involved in repairing DNA, loses its place. Lowering levels of that protein may prevent the expansion, Handsaker said.

Current experimental techniques for managing Huntington’s focus on lowering the levels of huntingtin. Another insight of the new research, Snell says, is these strategies may not be necessary.

The “work represents a very interesting potential paradigm shift for [Huntington’s] research,” says Leora Fox, Assistant Director of Research and Patient Engagement for the Huntington’s Disease Society of America in New York City. “Huntingtin lowering is not dead, but targeting [DNA] instability holds therapeutic potential.”

Computational biologist Liana Lareau agrees. The work is “a success story for single-cell sequencing,” which the researchers used to examine DNA and RNA in individual cells. The new insights would not have been possible without examining how DNA changes and gene activity are coordinated, says Lareau, of the University of California, Berkeley. And brain donations were also key, she says. “We can’t see this type of thing when we look at cells … in a dish. You need the full complexity of the natural environment.”