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Op-ed: Untangling the causes of obesity

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Tuesday, March 19, 2024

As researchers look for the reasons to explain the global rise in obesity, one thing has become clear — chemicals in our food, packaging, personal care items and other products are playing a key role. Obesity is linked to a variety of preventable health effects, such as type 2 diabetes, heart disease and even certain types of cancer. Despite the focus on treating obesity with diet and exercise, drugs and bariatric surgery, obesity is still increasing at alarming rates worldwide, especially in children. Evidence is mounting that certain chemicals called obesogens — which include everything from sugar to known bad actor chemicals like bisphenol-A (BPA), phthalates, flame retardants — can cause the human (and animal) body to produce more fat than it normally would. Many obesogens do this by impacting the proper functioning of our hormones, which means they can alter metabolism and promote increased storage of calories. Because of this, obesogens can increase weight gain even if we don’t eat more. In our new analysis, we examine the different models researchers use in studying obesity. We found that exposure to obesogens can result in changes in metabolism leading to weight gain that is consistent with the other models. We proposed an integrated model that puts exposure to obesogens as a key cause of obesity. A new approach is needed — one focusing on prevention. How scientists study obesity We compared four models that explain obesity development. The first model is the “calories in - calories out” idea: you gain weight if you eat more calories than you expend. It also says that something in the environment has changed over the last 50 or so years, unconsciously altering the brain, leading to increased food consumption and increased weight. The environmental change is not defined but researchers suspect ultra-processed foods are the culprit. The second model states that sugar is the culprit – specifically, high glycemic index carbohydrates that stimulate insulin. The increased insulin stimulates fat storage and increases how much we eat. Since the Western diet is high in sugar and ultra-processed foods, both of these models explain at least some of the current obesity epidemic. The third model — the obesogen model — states that obesogens alter metabolism. Most chemicals disrupt hormonal signaling pathways in various tissues that control energy intake, nutrient handling and body weight. Everyone is born pre-polluted with obesogens and exposure continues throughout life. Exposure to these obesogens at any time can increase weight gain but when it’s early in life (in utero and early childhood), it disrupts the normal development of fatty tissue, liver, gastrointestinal tract, brain and tissues regulating metabolism. These permanent changes can lead to obesity later in life, making it easier to gain weight and more challenging to lose it and to keep the weight off. The fourth model states that tissues have metabolism sensors that detect when there is sufficient fuel and produce small amounts of reactive oxygen species that tell the pancreas to release more insulin and fat tissue to make more fat. Both obesogens and ultra-processed foods stimulate these reactive oxygen species inappropriately in large amounts, which causes overeating. Obesogens are the common thread Obesogens are a unifying and key part of the obesity models, affecting all known key activities associated with both the first and second models.Regarding the “calories in - calories out” model, the changes that cause unconscious altered brain control of appetite can come from ultra-processed foods and obesogens (which also stimulate reactive oxygen species). Concerning the “sugar is the culprit” model, both obesogens and reactive oxygen species stimulate insulin, increasing fat storage. In the future, there should be less focus on individual models and more emphasis on a comprehensive model that includes obesogens and reactive oxygen species as essential contributors to obesity.How we can reduce obesogen exposure The good news is that we know many obesogens by name, chemicals that come from fossil fuels and plastics (BPA, phthalates, PFAS), flame retardants and some food additives, emulsifiers and colorants found in ultra-processed food. We also know where their exposures come from and how many act to increase weight gain. Decreasing human exposure to obesogens, particularly early in life, will prevent obesity. Personal changes can help, like filtering drinking water and using organic household products, cleaners and pesticides, and eliminating plastics, canned food and ultra-processed food.However, it is unrealistic to expect consumers or clinicians to prevent obesity alone. Instead, policymakers and regulators need to develop public health policies that will regulate and remove these harmful chemicals from products.Want to learn more? EHN’s guide to Obesogens: Chemicals that cause weight gain.Publication: Obesogens: a unifying theory for the global rise in obesity. Heindel JJ, Lustig RH, Howard S, Corkey BE. Int J Obes (Lond). 2024 Jan 11. doi: 10.1038/s41366-024-01460-3. Open access.Video: Are we there yet? Unifying model of obesity, by Nicholas Norwitz, about this paper.Webinar March 19, featuring Dr. Heindel: Obesogens: A unifying theory for the global rise in obesity. The webinar will be recorded and available at that link.Dr. Heindel coordinated three major review articles on obesogens published in 2022 in the journal Biomedical Pharmacology.

Obesity is linked to a variety of preventable health effects, such as type 2 diabetes, heart disease and even certain types of cancer. Despite the focus on treating obesity with diet and exercise, drugs and bariatric surgery, obesity is still increasing at alarming rates worldwide, especially in children.

Evidence is mounting that certain chemicals called obesogens — which include everything from sugar to known bad actor chemicals like bisphenol-A (BPA), phthalates, flame retardants — can cause the human (and animal) body to produce more fat than it normally would. Many obesogens do this by impacting the proper functioning of our hormones, which means they can alter metabolism and promote increased storage of calories. Because of this, obesogens can increase weight gain even if we don’t eat more.

In our new analysis, we examine the different models researchers use in studying obesity. We found that exposure to obesogens can result in changes in metabolism leading to weight gain that is consistent with the other models. We proposed an integrated model that puts exposure to obesogens as a key cause of obesity.

A new approach is needed — one focusing on prevention.

How scientists study obesity

We compared four models that explain obesity development. The first model is the “calories in - calories out” idea: you gain weight if you eat more calories than you expend. It also says that something in the environment has changed over the last 50 or so years, unconsciously altering the brain, leading to increased food consumption and increased weight. The environmental change is not defined but researchers suspect ultra-processed foods are the culprit.

The second model states that sugar is the culprit – specifically, high glycemic index carbohydrates that stimulate insulin. The increased insulin stimulates fat storage and increases how much we eat. Since the Western diet is high in sugar and ultra-processed foods, both of these models explain at least some of the current obesity epidemic.

The third model — the obesogen model — states that obesogens alter metabolism. Most chemicals disrupt hormonal signaling pathways in various tissues that control energy intake, nutrient handling and body weight. Everyone is born pre-polluted with obesogens and exposure continues throughout life. Exposure to these obesogens at any time can increase weight gain but when it’s early in life (in utero and early childhood), it disrupts the normal development of fatty tissue, liver, gastrointestinal tract, brain and tissues regulating metabolism. These permanent changes can lead to obesity later in life, making it easier to gain weight and more challenging to lose it and to keep the weight off.

The fourth model states that tissues have metabolism sensors that detect when there is sufficient fuel and produce small amounts of reactive oxygen species that tell the pancreas to release more insulin and fat tissue to make more fat. Both obesogens and ultra-processed foods stimulate these reactive oxygen species inappropriately in large amounts, which causes overeating.

Obesogens are the common thread

Obesogens are a unifying and key part of the obesity models, affecting all known key activities associated with both the first and second models.

Regarding the “calories in - calories out” model, the changes that cause unconscious altered brain control of appetite can come from ultra-processed foods and obesogens (which also stimulate reactive oxygen species). Concerning the “sugar is the culprit” model, both obesogens and reactive oxygen species stimulate insulin, increasing fat storage.

In the future, there should be less focus on individual models and more emphasis on a comprehensive model that includes obesogens and reactive oxygen species as essential contributors to obesity.

How we can reduce obesogen exposure

The good news is that we know many obesogens by name, chemicals that come from fossil fuels and plastics (BPA, phthalates, PFAS), flame retardants and some food additives, emulsifiers and colorants found in ultra-processed food. We also know where their exposures come from and how many act to increase weight gain. Decreasing human exposure to obesogens, particularly early in life, will prevent obesity.

Personal changes can help, like filtering drinking water and using organic household products, cleaners and pesticides, and eliminating plastics, canned food and ultra-processed food.

However, it is unrealistic to expect consumers or clinicians to prevent obesity alone. Instead, policymakers and regulators need to develop public health policies that will regulate and remove these harmful chemicals from products.

Want to learn more?

EHN’s guide to Obesogens: Chemicals that cause weight gain.

Publication: Obesogens: a unifying theory for the global rise in obesity. Heindel JJ, Lustig RH, Howard S, Corkey BE. Int J Obes (Lond). 2024 Jan 11. doi: 10.1038/s41366-024-01460-3. Open access.

Video: Are we there yet? Unifying model of obesity, by Nicholas Norwitz, about this paper.

Webinar March 19, featuring Dr. Heindel: Obesogens: A unifying theory for the global rise in obesity. The webinar will be recorded and available at that link.

Dr. Heindel coordinated three major review articles on obesogens published in 2022 in the journal Biomedical Pharmacology.

Read the full story here.

Photos courtesy of

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Costa Rica Shifts Toward Regenerative Tourism Alongside Other Nations

Costa Rica has long stood out for its commitment to protecting natural areas through tourism. Now, our country joins a growing number of nations that push beyond basic protection. They aim to restore and improve ecosystems damaged by past activities. This approach, called regenerative tourism, changes how visitors interact with places they travel to. In Costa Rica, tourism generates over 8 percent of the national economy and supports hundreds of thousands of jobs. For decades, the focus stayed on sustainability—keeping beaches clean, forests intact, and wildlife safe without causing more harm. But recent efforts show a clear move to regeneration. Local projects work to rebuild habitats, boost biodiversity, and strengthen communities hit hard by environmental changes. Take Punta Leona, a coastal area in Puntarenas. Hotels there add a small fee to each booking, with funds going directly to conserve local plants and animals. This has helped protect scarlet macaws and other species facing threats from habitat loss. In the Arenal area, Rancho Margot operates as a self-sustaining farm and lodge. It grows its own food, recycles water, and teaches guests how to plant trees that restore soil eroded by old farming practices. These actions do more than maintain the status quo; they repair what was lost. Costa Rica’s government backs this trend. The Tourism Board promotes programs that encourage visitors to join conservation work, such as planting mangroves along the Pacific coast or monitoring sea turtles in Tortuguero. A group called Costa Rica Regenerativa advises businesses on how to integrate regeneration into their operations. They focus on holistic plans that cover social, cultural, and environmental needs. As a result, areas like Monteverde see improved cloud forest health, with reforestation efforts bringing back native species absent for years. This shift aligns with global patterns. New Zealand sets a strong example. Its tourism authority invites travelers to participate in restoring native forests and waterways. In places like Rotorua, canopy tours fund projects that remove invasive plants and protect geothermal sites. The country reports higher visitor satisfaction when people contribute to these efforts, leading to longer stays and more repeat trips. Saudi Arabia takes a different path but shares the goal. It invests in large-scale regeneration in desert regions, turning arid lands into green spaces through water management and planting programs. Tourism there now includes experiences where guests help with these restorations, drawing interest from eco-conscious travelers. Finland emphasizes carbon neutrality in its northern landscapes. Cities like Helsinki offer tours that involve cleaning up lakes and planting boreal forests. This not only offsets travel emissions but also enhances wildlife corridors for species like reindeer. Ecuador’s Galápagos Islands provide another case. Strict rules limit visitor numbers, but regenerative programs let people assist in removing invasive species and monitoring marine life. Revenue from these activities funds habitat restoration, helping giant tortoises and other endemic animals thrive. In Mexico, Playa Viva on the Pacific coast runs as a regenerative resort. It restores mangroves and coastal dunes while involving local communities in decision-making. Guests leave with a sense of having improved the place they visited. These examples show regenerative tourism spreading across continents. It responds to rising awareness of climate change and biodiversity loss. Travelers today seek meaningful trips that give back, and nations like Costa Rica benefit from this demand. Studies from the World Travel & Tourism Council indicate that regenerative practices can increase tourism revenue by up to 20 percent in participating areas, as they attract higher-spending visitors. Challenges remain. Mass tourism can strain resources, as seen in some Costa Rican beaches where overcrowding leads to pollution. To counter this, experts call for better regulations and education. Community involvement stays key—local people must lead these initiatives to ensure they meet real needs. Looking ahead, Costa Rica plans to expand regenerative models nationwide. Partnerships with international organizations aim to share knowledge with other countries. This positions the nation as a guide in the field, showing how tourism can heal rather than just preserve. As more nations adopt this model, the travel industry may see lasting change. For us here in Costa Rica, it means building a healthier future for our land and people. The post Costa Rica Shifts Toward Regenerative Tourism Alongside Other Nations appeared first on The Tico Times | Costa Rica News | Travel | Real Estate.

Animals

Business

Climate

In Alaska’s Warming Arctic, Photos Show an Indigenous Elder Passing Down Hunting Traditions

An Inupiaq elder teaches his great-grandson to hunt in rapidly warming Northwest Alaska where thinning ice, shifting caribou migrations and severe storms are reshaping life

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Animals

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Changes in polar bear DNA that could help the animals adapt to warmer climates have been detected by researchers, in a study thought to be the first time a statistically significant link has been found between rising temperatures and changing DNA in a wild mammal species.Climate breakdown is threatening the survival of polar bears. Two-thirds of them are expected to have disappeared by 2050 as their icy habitat melts and the weather becomes hotter.Now scientists at the University of East Anglia have found that some genes related to heat stress, ageing and metabolism are behaving differently in polar bears living in south-east Greenland, suggesting they may be adjusting to warmer conditions.The researchers analysed blood samples taken from polar bears in two regions of Greenland and compared “jumping genes”: small, mobile pieces of the genome that can influence how other genes work. Scientists looked at the genes in relation to temperatures in the two regions and at the associated changes in gene expression.“DNA is the instruction book inside every cell, guiding how an organism grows and develops,” said the lead researcher, Dr Alice Godden. “By comparing these bears’ active genes to local climate data, we found that rising temperatures appear to be driving a dramatic increase in the activity of jumping genes within the south-east Greenland bears’ DNA.”As local climates and diets evolve as a result of changes in habitat and prey forced by global heating, the genetics of the bears appear to be adapting, with the group of bears in the warmest part of the country showing more changes than the communities farther north. The authors of the study have said these changes could help us understand how polar bears might survive in a warming world, inform understanding of which populations are most at risk and guide future conservation efforts.This is because the findings, published on Friday in the journal Mobile DNA, suggest the genes that are changing play a crucial role in how different polar bear populations are evolving.Godden said: “This finding is important because it shows, for the first time, that a unique group of polar bears in the warmest part of Greenland are using ‘jumping genes’ to rapidly rewrite their own DNA, which might be a desperate survival mechanism against melting sea ice.”Temperatures in north-east Greenland are colder and less variable, while in the south-east there is a much warmer and less icy environment, with steep temperature fluctuations.DNA sequences in animals change over time, but this process can be accelerated by environmental stress such as a rapidly heating climate.There were some interesting DNA changes, such as in areas linked to fat processing, that could help polar bears survive when food is scarce. Bears in warmer regions had more rough, plant-based diets compared with the fatty, seal-based diets of northern bears, and the DNA of south-eastern bears seemed to be adapting to this.Godden said: “We identified several genetic hotspots where these jumping genes were highly active, with some located in the protein-coding regions of the genome, suggesting that the bears are undergoing rapid, fundamental genetic changes as they adapt to their disappearing sea ice habitat.”The next step will be to look at other polar bear populations, of which there are 20 around the world, to see if similar changes are happening to their DNA.This research could help protect the bears from extinction. But the scientists said it was crucial to stop temperature rises accelerating by reducing the burning of fossil fuels.Godden said: “We cannot be complacent, this offers some hope but does not mean that polar bears are at any less risk of extinction. We still need to be doing everything we can to reduce global carbon emissions and slow temperature increases.”

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Extinction

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For the first time, scientists have cryopreserved and revived the larvae of a sea star species. The breakthrough, made with the giant pink star, gives hope the technique could be repeated to save the imperiled predator

A Deadly Pathogen Decimated Sunflower Sea Stars. Look Inside the Lab Working to Bring Them Back by Freezing and Thawing Their Larvae For the first time, scientists have cryopreserved and revived the larvae of a sea star species. The breakthrough, made with the giant pink star, gives hope the technique could be repeated to save the imperiled predator Juvenile sunflower sea stars at the Sunflower Star Laboratory in Moss Landing, California. At this phase, each is less than an inch wide, but they can grow to be more than three feet across as adults. Avery Schuyler Nunn Key takeaways: Recovering sunflower sea stars by freezing them in time Ravaged by infectious bacteria, sunflower sea stars literally wasted away across the Pacific coast of North America—and their resulting population crash destabilized kelp forest ecosystems. Scientists pioneered a cryopreservation technique on the closely related giant pink star, raising hopes that a bank of frozen sunflower star larvae could one day be thawed in the same way and released into the wild. Along a working California harbor, where gulls wheel over weathered pilings and the old Western Flyer—the ship John Steinbeck once sailed to the Sea of Cortez—sits restored in its berth, researchers buzz about in a modest lab tucked between warehouses and boatyards. Inside, amid the hiss of pumps and the faint smell of brine from seawater tables, a scientist lifts a small vial from a plume of liquid nitrogen, its frosted casing holding the tiniest flicker of hope for a species on the brink. Each of the 18 vials contains between 500 and 700 larval giant pink sea stars. At this stage, they are tiny specks suspended in seawater, invisible to the naked eye. These particular larvae have been cryopreserved and stored at roughly minus 180 degrees Celsius since March. At the Sunflower Star Laboratory (SSL) in Moss Landing, California, scientists thawed the larval pink sea stars and coaxed them to successfully develop into juveniles this summer—a first for any sea star species. In October, the scientists thawed another batch of larvae from the same cohort to test larval growth and survival under different freezing conditions and thawing protocols. The breakthrough, however, isn’t really about the giant pink star, a species that’s common in the wild. Instead, these larvae serve as a crucial stand-in for the far more imperiled sunflower sea star (Pycnopodia helianthoides)—a vanishing species for which larvae are precious, limited and increasingly difficult to obtain. Perfecting cryopreservation methods on pink stars—ensuring they can survive freezing, resume feeding and grow into juveniles—lays the scientific groundwork for facilitating a return of Pycnopodia. The contents of a thawed vial are placed under a microscope to assess viability of the larvae. Avery Schuyler Nunn The discovery arrives at a precarious time, as sunflower stars have disappeared at a pace rarely seen in marine ecosystems. As a mysterious pathogen ravaged their population along the western shores of North America beginning in 2013, the creatures collapsed from an estimated six billion individuals to functional extinction in parts of their range—all within just a few years. Their loss left kelp forests with dramatically fewer predators, destabilizing ecosystems across the Pacific coast and allowing urchins to proliferate and graze formerly lush underwater canopies into barren rock. Now, scientists hope that “freezing” their larvae will offer a new avenue for bringing the species back. “Cryopreservation is particularly important on the population level when thinking about recovery for this endangered species, because it had major population losses,” says Marissa Baskett, an environmental scientist at the University of California, Davis, who was not involved in the project. The process lets scientists preserve the sea stars’ existing genetic diversity for future reintroduction to the wild, she adds. “Especially given the uncertainty about different disease outbreaks, having that stock to return to is incredibly valuable.” A mysterious and “complete collapse” Sunflower sea stars have long lived in abundance up and down the rugged Pacific coast—from Alaskan archipelagoes to Baja California. The 24-limbed echinoderms sprawled across the seafloor in shades of ochre, crimson and violet. Among the fastest-moving and largest of all sea stars—capable of stretching nearly three feet across—these radiant predators coursed through kelp forests, voraciously hunting purple sea urchins and preventing them from over-grazing on the holdfasts that root towering golden canopies of kelp. An adult sunflower sea star has 24 limbs and can be more than three feet wide. This one was photographed off Point Dume State Beach near Los Angeles. Brent Durand via Getty Images “In Northern California and Oregon, there historically would have been multiple keystone predators within the kelp forest ecosystem who are punching on purple urchins and keeping their population in check,” says Reuven Bank, board chair of SSL. “But the southern sea otter was extirpated across its historic range, so we were left with sunflower stars being the last major keystone predator of purple urchins across over 100 miles of coastline.” “And sunflower stars didn’t just eat urchins, they scared them,” Bank adds. “Urchins can smell a sunflower star approaching, and in healthy kelp forests they hide more and graze less. Even without consuming them, sunflower stars helped keep urchin behavior, and therefore kelp forests, in balance.” Then, in June 2013, tidepool monitors along Washington’s Olympic Peninsula documented an unprecedented sight. The once-sturdy sea stars had turned soft, pale and contorted, their arms curling and detaching from their bodies. By late summer, the same mysterious affliction had surfaced in British Columbia, and it began sweeping both north and south with startling speed. The emerging epidemic, which caused the invertebrates to literally disintegrate, would soon be known as sea star wasting disease. An infamous marine heatwave—nicknamed “The Blob”—had settled over the Pacific by 2014, thrusting the coast into a fever. Ocean temperatures spiked, likely speeding up the disease progression in already stressed sea stars and leading to higher mortality. In the warm, stagnant water, infected sunflower stars dissolved at an eerily rapid pace, leaving behind ghost-white films of bacterial mass where the vibrant predators had been just days before. “You’d have apparently healthy stars basically melt away into puddles of goo within 48 hours,” says Andrew Kim, lab manager at SSL. “It happened so quickly, and I don’t think folks were prepared for the ensuing ecosystem shift. You don’t often expect diseases to come through and totally reshape ecosystem dynamics within such a short period. But that’s what we saw.” Without sunflower sea stars to keep those spiny purple urchins in check, the balance began to falter, setting the stage for an unprecedented chain reaction. Urchin populations skyrocketed, grazing on kelp without limits, and once-thriving underwater forests collapsed into barren rock. A dense group of purple sea urchins, which exploded in population after the sunflower sea stars disappeared, photographed near Mendocino Headlands State Park, north of San Francisco. Brent Durand via Getty Images In California, with 99 percent loss, sunflower sea stars are now considered functionally extinct. “Even though there may be a few remnant individuals left, they can no longer fulfill their historic role in the ecosystem,” Bank says. As sunflower stars unraveled in the wild, another species—its thick-armed cousin, the giant pink star—offered an unexpected foothold for hope. The pink stars share a nearly identical geographic range and life history with sunflower stars, and crucially, their larvae can be raised in aquaria. If scientists could learn to freeze and revive the pink star in its early life stages, they wondered, could that knowledge become a lifeline for the sunflower star? That’s where the small team in Moss Landing stepped in. Freezing sea stars for the future What these scientists did was something no one had ever pulled off with a sea star. Working with giant pink stars, researchers spawned adults at the Aquarium of the Pacific in Long Beach, California, fertilized their gametes to produce thousands of larvae, and shipped those microscopic bodies to the Frozen Zoo—a cryopreserved archive of creatures operated by the San Diego Zoo Wildlife Alliance. There, reproductive scientists plunged the larvae into liquid nitrogen, cooling them to extremely low temperatures and pausing their cells’ biological activity. The larvae, essentially frozen in time, were shielded from ice crystal damage with special cryoprotectant mixtures. Sunflower Star Laboratory researchers remove a vial of pink star larvae from an insulated cooler at around minus 180 degrees Celsius in preparation for thawing. Avery Schuyler Nunn After months in this suspended state, the larvae were sent to the Sunflower Star Laboratory where Carly Young, a San Diego Zoo Wildlife Alliance scientist who advances cryopreservation and reproductive-rescue tools, led the team in thawing the vials. She had fine-tuned the ideal way to keep the larvae alive as they returned to real-world temperatures, carefully testing more than 100 “recipes” with various warming rates, cryoprotectant dilutions and rehydration steps. The pink star larvae not only survived thawing, but have thus far lived all the way through metamorphosis into juveniles. Scientists watched the little stars settle spontaneously along the bottom of their beakers just 19 days after revival. The success prompted the team to apply the same cryopreservation protocols to sunflower star larvae from the Alaska SeaLife Center. The larvae will be frozen in perpetuity, creating the first-ever cryopreserved archive of the species—like a seed bank, but for the baby sea stars. “A famous quote from the ’70s, when the Frozen Zoo in San Diego was established, was, ‘You must collect things for reasons you don’t yet understand,’” says Ashley Kidd, conservation project manager at SSL. “We don’t know when the other shoe is going to drop and what populations are going to look like as the planet changes. So, rather than chasing ghosts around the ocean floor, we really focused on what we can do with animals that are currently under human care somewhere.” While cryopreservation itself isn’t a ready-made restoration tool, it opens the door to conserving genetic diversity of a species and banking rare lineages for potential reintroduction to the wild. In the 1970s and 1990s, researchers began testing cryopreservation of marine invertebrates with sperm and larvae, establishing the basic protocols that this team could apply to sea stars. The breakthrough doesn’t restore kelp forests by itself, but the SSL scientists note that cryopreservation creates something the conservation community has desperately needed: time. Time to hold onto genetic diversity, time to refine captive rearing and time to prepare for future reintroduction at scales big enough to matter. The ultimate test, the researchers say, will be translating the thawing process to sunflower sea stars. Carly Young, at the Sunflower Star Laboratory, looks for movement in the young sea stars. Avery Schuyler Nunn Just this summer, scientists uncovered a piece of the puzzle that had eluded them for more than a decade: the pathogen behind sea star wasting disease. In a four-year international effort, researchers traced the outbreak to a strain of the marine bacterium Vibrio pectenicida. When cultured and injected into healthy sea stars, it reproduced the telltale symptoms—softening arms, rapid disintegration and death within days. The finding, published in Nature Ecology and Evolution in August, gives recovery teams a way to test for the pathogen in labs and hatcheries, tighten quarantine measures and understand disease risks before returning captive-bred sea stars to the Pacific. “It’s massively important to know what to look for, and the fact that we are now able to test for this disease is going to be critical in advancing our ability to move forward with reintroductions and continuing the research,” notes Kim. “We’ve already been able to take fluid samples from all of our stars and get them analyzed for the presence of Vibrio pectenicida, so we’ve mobilized very quickly on the heels of development.” Paired with this new diagnostic clarity, advances in cryopreservation offer a second front in the effort to save the species. Frozen larvae can be stored for decades and offer flexibility for selective breeding of disease-tolerant traits, notes the team. Cryopreservation adds another tool to the scientists’ toolbox as they fight to prevent the species—and, in turn, its ecosystem—from wasting away. “Bringing back sunflower stars,” Bank says, “is the single-most important step we can take toward restoring kelp forest balance.” Get the latest Science stories in your inbox.

Animals

Conservation

Culture

Archaeologists Are Unraveling the Mysteries Behind Deep Pits Found Near Stonehenge

Based on a comprehensive study, researchers are now convinced the shafts were human-made, likely dug during the Late Neolithic period roughly 4,000 years ago

Archaeologists Are Unraveling the Mysteries Behind Deep Pits Found Near Stonehenge Based on a comprehensive study, researchers are now convinced the shafts were human-made, likely dug during the Late Neolithic period roughly 4,000 years ago Sarah Kuta - Daily Correspondent December 10, 2025 9:59 a.m. The pits are evenly spaced around a large circle. University of Bradford In 2020, archaeologists in the United Kingdom made a surprising discovery. At Durrington Walls, a large Neolithic henge not far from Stonehenge, they found more than a dozen large, deep pits buried under layers of loose clay. The pits are mysterious. Each one measures roughly 30 feet wide by 15 feet deep, and together they form a mile-wide circle around Durrington Walls and neighboring Woodhenge. They also appear to be linked with the much older Larkhill causewayed enclosure, built more than 1,000 years before Durrington Walls. For the last few years, archaeologists have been puzzling over their origins: Were they dug intentionally by human hands? Were they naturally occurring structures, like sinkholes? Or is there some other possible explanation for the existence of these colossal shafts? Quick fact: The purpose of Durrington Walls While Stonehenge is thought to have been a sacred place for ceremonies, Durrington Walls was a place where people actually lived. In a new paper published in the journal Internet Archaeology, archaeologists report that they have a much better understanding of the pits’ purpose, chronology and environmental setting. And, now, they are confident the shafts were made by humans. “They can’t be occurring naturally,” says lead author Vincent Gaffney, an archaeologist at the University of Bradford, to the Guardian’s Steven Morris. “It just can’t happen. We think we’ve nailed it.” Chris Gaffney, an archaeologist at the at the University of Bradford, surveys the ground near Durrington Walls. University of Bradford For the study, researchers returned to the site in southern England and used several different methods to further analyze the unusual structures. They used a technique known as electrical resistance tomography to calculate the pits’ depths, and radar and magnetometry to suss out their shapes. They also took core samples of the sediment, then ran the soil through a variety of tests. For instance, they used optically stimulated luminescence to determine the last time each layer of soil had been exposed to the sun. They also looked for traces of animal or plant DNA. Astonishing' Stonehenge discovery offers new insights into Neolithic ancestors. Together, the results of these analyses indicate humans must have been involved, which suggests the pits could be “one of the largest prehistoric structures in Britain, if not the largest,” Gaffney tells the BBC’s Sophie Parker. Researchers suspect the circle pits were created by people living at the site over a short period of time during the Late Neolithic period roughly 4,000 years ago. They were not “simply dug and abandoned” but, rather, appear to have been part of a “structured, monumental landscape that speaks to the complexity and sophistication of Neolithic society,” Gaffney says in a statement. For example, the pits are fairly evenly spaced around the circle, which suggests their Neolithic creators were measuring the distances between them somehow. “The skill and effort that must have been required to not only dig the pits, but also to place them so precisely within the landscape is a marvel,” says study co-author Richard Bates, a geophysicist at the University of St Andrews, in a statement. “When you consider that the pits are spread over such a large distance, the fact they are located in a near perfect circular pattern is quite remarkable.” Researchers used multiple methods to investigate the pits at Durrington Walls. University of Bradford But who dug the pits? And, perhaps more importantly, why? Archaeologists are still trying to definitively answer those questions, but they suspect the shafts were created to serve as some sort of sacred boundary around Durrington Walls. Their creators may also have been trying to connect with the underworld, per the Guardian. “They’re inscribing something about their cosmology, their belief systems, into the earth itself in a very dramatic way,” Gaddney tells the BBC. Get the latest stories in your inbox every weekday.

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