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Study finds levels of a dangerous gas “off the scales” in Central Texas oilfield

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Friday, September 20, 2024

Sign up for The Brief, The Texas Tribune’s daily newsletter that keeps readers up to speed on the most essential Texas news. The first readings Abigail Edgar took of hydrogen sulfide and methane at oilfields in Caldwell County in 2021 were so high that she thought her equipment was malfunctioning. “It was off the scales. Methane was off the scales and hydrogen sulfide was off the scales,” said Edgar, a master’s student in geography at Texas State University. “The monitor would immediately start beeping when I crossed the property line.” Edgar was recording dangerous levels of hydrogen sulfide at wells on private property in Caldwell County, 30 miles southeast of Austin. Hydrogen sulfide is a toxic and highly flammable gas often found in oil and gas formations. During the course of her research, the gas was so potent at three separate wells that Edgar’s respirator did not provide enough protection and she had to leave for her safety. Edgar teamed up with University of Cincinnati environmental scientist Amy Townsend-Small, an expert on methane, to take another round of measurements in 2023. They found the wells were directly releasing gas — including hydrogen sulfide and methane — into the atmosphere in a process called venting. Some of the wells venting gas were alongside public roads. Others were next to backyards and driveways. In a paper published in Environmental Research Communications last week, Edgar, Townsend-Small and other authors at Texas State University and the University of Maryland report hydrogen sulfide readings at 46 wells around Caldwell County. Hydrogen sulfide concentrations at 13 of the wells were at least 300 parts per million (ppm) — the maximum reading on the measuring device. Eight other sites had readings over 100 ppm. Exposure to 100 ppm of hydrogen sulfide is immediately dangerous to life or health, according to the National Institute for Occupational Safety and Health. The study warns these hydrogen sulfide levels are a hazard for people living and working in the area. “Here in Texas we rely heavily on the oil industry and protect the oil industry. And I think rightfully so,” Edgar said. “But there has to be something done for these neighbors. We’re slowly poisoning these communities.” Abigail Edgar, left, and Amy Townsend-Small observe a bubbling gas leak at a well that state records list as inactive in May 2023. Credit: Courtesy of Abigail Edgar Oilfield companies are required to adopt protocols to protect workers from hydrogen sulfide. But the general public is often exposed to low-level concentrations. The gas can disperse for miles downwind, especially during cold weather. Symptoms of low to mid-level hydrogen sulfide exposure include headaches, nausea, coughing and nose and eye irritation. The gas is also present at landfills, wastewater treatment facilities and large animal feedlots. State rules prohibit the waste of natural gas through venting and flaring except under certain circumstances. But researchers found that venting was commonplace in Caldwell County after the gas processing plant there closed down in 2017. Inside Climate News found that the Railroad Commission of Texas, which regulates oil and gas extraction, has not issued any recent exceptions for venting or flaring gas in the county. The most important Texas news,sent weekday mornings. The agency did not respond to questions about gas venting or hydrogen sulfide exposure in the area. Spokesperson Patty Ramon said, “Our rules, permitting and inspection systems are designed to protect public safety and the environment.” The Texas Commission on Environmental Quality (TCEQ) regulates ambient concentrations of hydrogen sulfide. Agency spokesperson Richard Richter said that the measurements in the study cannot be used to evaluate the exposure to the general public. He said that in an unspecified number of TCEQ investigations in Caldwell County since 2017 the H2S concentrations in ambient air did not exceed state standards. Production flatlined in the Luling oilfield The railroad town of Luling in Caldwell County, about 50 miles south of Austin, boomed after Edgar B. Davis struck oil in 1922. Wells in the Luling oilfield cut diagonally across the county, dotting unincorporated areas like Stairtown and within the Luling city limits. The oil patch was largely tapped out by the 1980s, but low-production wells keep pumping to this day. In June 2024, the most recent month with available data, operators in Caldwell County reported producing less than 71,000 barrels of oil. That places Caldwell at 63 out of 199 oil-producing counties in Texas that month. Amid production declines, the Luling Oil Museum still invites visitors to learn about the town’s drilling heritage. The other main attraction in Luling, population 5,500, is the annual Watermelon Thump festival. The Luling oilfield is one of many across Texas characterized by gas high in hydrogen sulfide. An aging oil well in Caldwell County. Seen on the ground at the left side of the well head is an open vent releasing hydrogen sulfide. Researchers measured over 300 ppm of the dangerous gas at the well head. Credit: Courtesy of Abigail Edgar The pungent “rotten egg” smell emanating from the Luling oil fields is so ubiquitous that local media outlets have dubbed it the “Luling effect.” People as far as Austin have called 911 to report the smell, which comes from hydrogen sulfide and other chemicals. The Railroad Commission implements State Rule 36, requiring operators to report the hydrogen sulfide concentration at wells, determine the radius of exposure and report any accidental releases of hydrogen sulfide. Operators are required to install signs and restrict public access to sites with a risk of exposure. Groundlevel hydrogen sulfide concentrations over 0.08 ppm, averaged over a 30-minute period, are prohibited by state law if the emissions affect residential or commercial property. In an investigation earlier this year, the Houston Chronicle and The Examination found that residents in the Permian Basin often report symptoms of hydrogen sulfide exposure, but state regulators rarely issue meaningful penalties to the companies responsible for the pollution. When the TCEQ records elevated H2S levels in ambient air, the agency’s goal is to identify the source and ensure the emissions are stopped, its spokesperson said. He reiterated that because the study’s measurements were taken at the wellhead, the readings were not in violation of TCEQ standards. Low producing oil wells, but high hydrogen sulfide emissions Texas State University’s Edgar contacted landowners in Caldwell County to find sites to measure hydrogen sulfide and methane emissions. Edgar said that the landowners were unaware that gas was being directly vented on their property. She said one resident had been asked by his doctor if he could be suffering hydrogen sulfide poisoning. “They were happy to have somebody take notice of it,” she said. The researchers selected 46 wells to study. The oldest had been drilled in the 1930s, but most were drilled in the 1960s through 1980s. All the wells are considered marginal, with less than 15 barrels of oil production a day. (In contrast, fracked wells in Texas can produce thousands of barrels a day.) The team took direct measurements from the wellhead using a Bascom-Turner Gas Rover and an Indaco Hi-Flow Sampler. Hydrogen sulfide was measured over a five-minute period. The methane emissions measured at the wells were similar to previous studies of marginal oil wells. Hydrogen sulfide concentrations ranged from zero parts per million to at least 300 parts per million, the maximum reading on the Gas Rover. Hydrogen sulfide can be immediately lethal at concentrations over 700 ppm. Exposure to more than 500 ppm will cause people to collapse within five minutes. An oilfield worker and his wife were killed by hydrogen sulfide exposure in Odessa in 2019. Hydrogen sulfide dissipates and would be found in lower concentrations in public areas near the wells. While not as well understood as acute, high-level exposure, research shows that chronic, low-level hydrogen sulfide exposure also has health effects. One 2023 literature review of over 100 previous studies found that chronic community hydrogen sulfide exposure at average concentrations below 0.01 ppm has been associated with health effects including eye, nose, respiratory and neurological symptoms. The authors write that individuals with underlying health conditions such as asthma could be particularly at risk. The University of Cincinnati’s Townsend-Small said the Caldwell County wells are deserving of study because of the anecdotal evidence of strong hydrogen sulfide smells and their proximity to large urban areas. “These wells are so close to so many people,” she said. “And they are emitting a hazardous substance that could be affecting so many people.” Townsend-Small said plugging the Caldwell County wells or capturing the gas is “low-hanging fruit” to reduce methane emissions and health effects of hydrogen sulfide without significant impacts to oil production. Edgar said it is unclear whether the Railroad Commission or the TCEQ is responsible for regulating venting at oil wells when it contributes to air pollution. She said one simple step would be for Railroad Commission staff to record hydrogen sulfide levels when they make field visits in Caldwell County. “I was not able to come up with any good answers to whose fault is this, who should fix it, and how it should be fixed,” she said. She said her greatest concern is for oilfield workers and neighbors who live next door to wells. “Part of being in the oilfields” Luling city manager Mark Mayo said people coming through town often comment on the smell. But Mayo, who grew up in the Permian Basin, is no stranger to the odor of sour gas. He said he didn’t think Luling residents are at risk from hydrogen sulfide. “Just because it has a smell doesn’t mean it’s always bad,” he said. “That’s part of being in the oilfield.” Credit: Martha Pskowski/Inside Climate News But he took note of discrepancies documented in the study. Researchers found that some wells listed as “active” with the Railroad Commission were no longer producing. Others listed as “inactive” or “plugged” were still producing. Mayo said the city relies on the agency to ensure oil companies are following state rules, including those for hydrogen sulfide. “That’s the Railroad Commission’s place,” he said. “As far as the city, we don’t have the ability or the equipment to stay up on that.” Air quality experts have long known that Caldwell County is a locus of hydrogen sulfide emissions. But there are no stationary hydrogen sulfide monitors to track community levels of exposure. Neil Carman, the Lone Star Sierra Club’s clean air director, previously worked as an air pollution control inspector for the TCEQ. Carman said to prove that emissions exceed the TCEQ standards would require 30-minute readings, subtracting any contributions of hydrogen sulfide from upwind, instead of the five-minute measurements of the study. But he did not doubt that excess hydrogen sulfide is being released. “Luling, Texas, there is a huge mess out there,” he said. “I’ve been through many times. I’d say almost every time I’d get a headache.” Carman said that memory loss and insomnia are other frequent symptoms of exposure. “It's really unacceptable and outrageous to the people in these communities,” Carman said. Sharon Wilson of the nonprofit Oilfield Witness has researched compliance with the Railroad Commission’s hydrogen sulfide rules. In a previous report, she found that many companies fail to submit the H9 form reporting the hydrogen sulfide level at wells. “Texas has a gas problem. We have a hydrogen sulfide problem and it's putting people at risk,” Wilson said. “We see the high levels of hydrogen sulfide from the few air monitors there are in the Permian Basin.” Wilson travels the Texas oil fields measuring methane emissions with a thermal camera. She said often the hydrogen sulfide fumes are so overwhelming she can’t leave her vehicle. “Texans are not receiving equal protection from oil and gas pollution,” she said. “We need more monitors in all areas of oil and gas activity.”

The smell of oil wells has long permeated Caldwell County, near Austin and San Antonio. Now researchers have documented wells releasing dangerous amounts of hydrogen sulfide gas.

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The first readings Abigail Edgar took of hydrogen sulfide and methane at oilfields in Caldwell County in 2021 were so high that she thought her equipment was malfunctioning.

“It was off the scales. Methane was off the scales and hydrogen sulfide was off the scales,” said Edgar, a master’s student in geography at Texas State University. “The monitor would immediately start beeping when I crossed the property line.”

Edgar was recording dangerous levels of hydrogen sulfide at wells on private property in Caldwell County, 30 miles southeast of Austin. Hydrogen sulfide is a toxic and highly flammable gas often found in oil and gas formations. During the course of her research, the gas was so potent at three separate wells that Edgar’s respirator did not provide enough protection and she had to leave for her safety.

Edgar teamed up with University of Cincinnati environmental scientist Amy Townsend-Small, an expert on methane, to take another round of measurements in 2023. They found the wells were directly releasing gas — including hydrogen sulfide and methane — into the atmosphere in a process called venting. Some of the wells venting gas were alongside public roads. Others were next to backyards and driveways.

In a paper published in Environmental Research Communications last week, Edgar, Townsend-Small and other authors at Texas State University and the University of Maryland report hydrogen sulfide readings at 46 wells around Caldwell County. Hydrogen sulfide concentrations at 13 of the wells were at least 300 parts per million (ppm) — the maximum reading on the measuring device. Eight other sites had readings over 100 ppm. Exposure to 100 ppm of hydrogen sulfide is immediately dangerous to life or health, according to the National Institute for Occupational Safety and Health. The study warns these hydrogen sulfide levels are a hazard for people living and working in the area.

“Here in Texas we rely heavily on the oil industry and protect the oil industry. And I think rightfully so,” Edgar said. “But there has to be something done for these neighbors. We’re slowly poisoning these communities.”

Abigail Edgar, left, and Amy Townsend-Small observe a bubbling gas leak at a well that state records list as inactive in May 2023. Credit: Courtesy of Abigail Edgar

Oilfield companies are required to adopt protocols to protect workers from hydrogen sulfide. But the general public is often exposed to low-level concentrations. The gas can disperse for miles downwind, especially during cold weather. Symptoms of low to mid-level hydrogen sulfide exposure include headaches, nausea, coughing and nose and eye irritation. The gas is also present at landfills, wastewater treatment facilities and large animal feedlots.

State rules prohibit the waste of natural gas through venting and flaring except under certain circumstances. But researchers found that venting was commonplace in Caldwell County after the gas processing plant there closed down in 2017. Inside Climate News found that the Railroad Commission of Texas, which regulates oil and gas extraction, has not issued any recent exceptions for venting or flaring gas in the county.

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sent weekday mornings.

The agency did not respond to questions about gas venting or hydrogen sulfide exposure in the area. Spokesperson Patty Ramon said, “Our rules, permitting and inspection systems are designed to protect public safety and the environment.”

The Texas Commission on Environmental Quality (TCEQ) regulates ambient concentrations of hydrogen sulfide. Agency spokesperson Richard Richter said that the measurements in the study cannot be used to evaluate the exposure to the general public. He said that in an unspecified number of TCEQ investigations in Caldwell County since 2017 the H2S concentrations in ambient air did not exceed state standards.

Production flatlined in the Luling oilfield

The railroad town of Luling in Caldwell County, about 50 miles south of Austin, boomed after Edgar B. Davis struck oil in 1922. Wells in the Luling oilfield cut diagonally across the county, dotting unincorporated areas like Stairtown and within the Luling city limits.

The oil patch was largely tapped out by the 1980s, but low-production wells keep pumping to this day. In June 2024, the most recent month with available data, operators in Caldwell County reported producing less than 71,000 barrels of oil. That places Caldwell at 63 out of 199 oil-producing counties in Texas that month.

Amid production declines, the Luling Oil Museum still invites visitors to learn about the town’s drilling heritage. The other main attraction in Luling, population 5,500, is the annual Watermelon Thump festival.

The Luling oilfield is one of many across Texas characterized by gas high in hydrogen sulfide.

An aging oil well in Caldwell County. Seen on the ground at the left side of the well head is an open vent releasing hydrogen sulfide. Researchers measured over 300 ppm of the dangerous gas at the well head. Credit: Courtesy of Abigail Edgar

The pungent “rotten egg” smell emanating from the Luling oil fields is so ubiquitous that local media outlets have dubbed it the “Luling effect.” People as far as Austin have called 911 to report the smell, which comes from hydrogen sulfide and other chemicals.

The Railroad Commission implements State Rule 36, requiring operators to report the hydrogen sulfide concentration at wells, determine the radius of exposure and report any accidental releases of hydrogen sulfide. Operators are required to install signs and restrict public access to sites with a risk of exposure.

Groundlevel hydrogen sulfide concentrations over 0.08 ppm, averaged over a 30-minute period, are prohibited by state law if the emissions affect residential or commercial property. In an investigation earlier this year, the Houston Chronicle and The Examination found that residents in the Permian Basin often report symptoms of hydrogen sulfide exposure, but state regulators rarely issue meaningful penalties to the companies responsible for the pollution.

When the TCEQ records elevated H2S levels in ambient air, the agency’s goal is to identify the source and ensure the emissions are stopped, its spokesperson said. He reiterated that because the study’s measurements were taken at the wellhead, the readings were not in violation of TCEQ standards.

Low producing oil wells, but high hydrogen sulfide emissions

Texas State University’s Edgar contacted landowners in Caldwell County to find sites to measure hydrogen sulfide and methane emissions.

Edgar said that the landowners were unaware that gas was being directly vented on their property. She said one resident had been asked by his doctor if he could be suffering hydrogen sulfide poisoning.

“They were happy to have somebody take notice of it,” she said.

The researchers selected 46 wells to study. The oldest had been drilled in the 1930s, but most were drilled in the 1960s through 1980s. All the wells are considered marginal, with less than 15 barrels of oil production a day. (In contrast, fracked wells in Texas can produce thousands of barrels a day.) The team took direct measurements from the wellhead using a Bascom-Turner Gas Rover and an Indaco Hi-Flow Sampler. Hydrogen sulfide was measured over a five-minute period.

The methane emissions measured at the wells were similar to previous studies of marginal oil wells. Hydrogen sulfide concentrations ranged from zero parts per million to at least 300 parts per million, the maximum reading on the Gas Rover.

Hydrogen sulfide can be immediately lethal at concentrations over 700 ppm. Exposure to more than 500 ppm will cause people to collapse within five minutes. An oilfield worker and his wife were killed by hydrogen sulfide exposure in Odessa in 2019.

Hydrogen sulfide dissipates and would be found in lower concentrations in public areas near the wells. While not as well understood as acute, high-level exposure, research shows that chronic, low-level hydrogen sulfide exposure also has health effects. One 2023 literature review of over 100 previous studies found that chronic community hydrogen sulfide exposure at average concentrations below 0.01 ppm has been associated with health effects including eye, nose, respiratory and neurological symptoms. The authors write that individuals with underlying health conditions such as asthma could be particularly at risk.

The University of Cincinnati’s Townsend-Small said the Caldwell County wells are deserving of study because of the anecdotal evidence of strong hydrogen sulfide smells and their proximity to large urban areas.

“These wells are so close to so many people,” she said. “And they are emitting a hazardous substance that could be affecting so many people.”

Townsend-Small said plugging the Caldwell County wells or capturing the gas is “low-hanging fruit” to reduce methane emissions and health effects of hydrogen sulfide without significant impacts to oil production.

Edgar said it is unclear whether the Railroad Commission or the TCEQ is responsible for regulating venting at oil wells when it contributes to air pollution. She said one simple step would be for Railroad Commission staff to record hydrogen sulfide levels when they make field visits in Caldwell County.

“I was not able to come up with any good answers to whose fault is this, who should fix it, and how it should be fixed,” she said.

She said her greatest concern is for oilfield workers and neighbors who live next door to wells.

“Part of being in the oilfields”

Luling city manager Mark Mayo said people coming through town often comment on the smell.

But Mayo, who grew up in the Permian Basin, is no stranger to the odor of sour gas. He said he didn’t think Luling residents are at risk from hydrogen sulfide.

“Just because it has a smell doesn’t mean it’s always bad,” he said. “That’s part of being in the oilfield.”

Credit: Martha Pskowski/Inside Climate News

But he took note of discrepancies documented in the study. Researchers found that some wells listed as “active” with the Railroad Commission were no longer producing. Others listed as “inactive” or “plugged” were still producing. Mayo said the city relies on the agency to ensure oil companies are following state rules, including those for hydrogen sulfide.

“That’s the Railroad Commission’s place,” he said. “As far as the city, we don’t have the ability or the equipment to stay up on that.”

Air quality experts have long known that Caldwell County is a locus of hydrogen sulfide emissions. But there are no stationary hydrogen sulfide monitors to track community levels of exposure.

Neil Carman, the Lone Star Sierra Club’s clean air director, previously worked as an air pollution control inspector for the TCEQ. Carman said to prove that emissions exceed the TCEQ standards would require 30-minute readings, subtracting any contributions of hydrogen sulfide from upwind, instead of the five-minute measurements of the study. But he did not doubt that excess hydrogen sulfide is being released.

“Luling, Texas, there is a huge mess out there,” he said. “I’ve been through many times. I’d say almost every time I’d get a headache.”

Carman said that memory loss and insomnia are other frequent symptoms of exposure.

“It's really unacceptable and outrageous to the people in these communities,” Carman said.

Sharon Wilson of the nonprofit Oilfield Witness has researched compliance with the Railroad Commission’s hydrogen sulfide rules. In a previous report, she found that many companies fail to submit the H9 form reporting the hydrogen sulfide level at wells.

“Texas has a gas problem. We have a hydrogen sulfide problem and it's putting people at risk,” Wilson said. “We see the high levels of hydrogen sulfide from the few air monitors there are in the Permian Basin.”

Wilson travels the Texas oil fields measuring methane emissions with a thermal camera. She said often the hydrogen sulfide fumes are so overwhelming she can’t leave her vehicle.

“Texans are not receiving equal protection from oil and gas pollution,” she said. “We need more monitors in all areas of oil and gas activity.”

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Giant Sloths and Many Other Massive Creatures Were Once Common on Our Planet. With Environmental Changes, Such Giants Could Thrive Again

If large creatures like elephants, giraffes and bison are allowed to thrive, they could alter habitats that allow for the rise of other giants

Giant Sloths and Many Other Massive Creatures Were Once Common on Our Planet. With Environmental Changes, Such Giants Could Thrive Again If large creatures like elephants, giraffes and bison are allowed to thrive, they could alter habitats that allow for the rise of other giants Riley Black - Science Correspondent July 11, 2025 8:00 a.m. Ancient sloths lived in trees, on mountains, in deserts, in boreal forests and on open savannas. Some grew as large as elephants. Illustration by Diego Barletta The largest sloth of all time was the size of an elephant. Known to paleontologists as Eremotherium, the shaggy giant shuffled across the woodlands of the ancient Americas between 60,000 and five million years ago. Paleontologists have spent decades hotly debating why such magnificent beasts went extinct, the emerging picture involving a one-two punch of increasing human influence on the landscape and a warmer interglacial climate that began to change the world’s ecosystems. But even less understood is how our planet came to host entire communities of such immense animals during the Pleistocene. Now, a new study on the success of the sloths helps to reveal how the world of Ice Age giants came to be, and hints that an Earth brimming with enormous animals could come again. Florida Museum of Natural History paleontologist Rachel Narducci and colleagues tracked how sloths came to be such widespread and essential parts of the Pleistocene Americas and published their findings in Science this May. The researchers found that climate shifts that underwrote the spread of grasslands allowed big sloths to arise, the shaggy mammals then altering those habitats to maintain open spaces best suited to big bodies capable of moving long distances. The interactions between the animals and environment show how giants attained their massive size, and how strange it is that now our planet has fewer big animals than would otherwise be here. Earth still boasts some impressively big species. In fact, the largest animal of all time is alive right now and only evolved relatively recently. The earliest blue whale fossils date to about 1.5 million years ago, and, at 98 feet long and more than 200 tons, the whale is larger than any mammoth or dinosaur. Our planet has always boasted a greater array of small species than large ones, even during prehistoric ages thought of as synonymous with megafauna. Nevertheless, Earth’s ecosystems are still in a megafaunal lull that began at the close of the Ice Age. “I often say we are living on a downsized planet Earth,” says University of Maine paleoecologist Jacquelyn Gill.Consider what North America was like during the Pleistocene, between 11,000 years and two million ago. The landmass used to host multiple forms of mammoths, mastodons, giant ground sloths, enormous armadillos, multiple species of sabercat, huge bison, dire wolves and many more large creatures that formed ancient ecosystems unlike anything on our planet today. In addition, many familiar species such as jaguars, black bears, coyotes, white-tailed deer and golden eagles also thrived. Elsewhere in the world lived terror birds taller than an adult human, wombats the size of cars, woolly rhinos, a variety of elephants with unusual tusks and other creatures. Ecosystems capable of supporting such giants have been the norm rather than the exception for tens of millions of years. Giant sloths were among the greatest success stories among the giant-size menagerie. The herbivores evolved on South America when it was still an island continent, only moving into Central and North America as prehistoric Panama connected the landmasses about 2.7 million years ago. Some were small, like living two- and three-toed sloths, while others embodied a range of sizes all the way up to elephant-sized giants like Eremotherium and the “giant beast” Megatherium. An Eremotherium skeleton at the Houston Museum of Natural Science demonstrates just how large the creature grew. James Nielsen / Houston Chronicle via Getty Images The earliest sloths originated on South America about 35 million years ago. They were already big. Narducci and colleagues estimate that the common ancestor of all sloths was between about 150 and 770 pounds—or similar to the range of sizes seen among black bears today—and they walked on the ground. “I was surprised and thrilled” to find that sloths started off large, Narducci says, as ancestral forms of major mammal groups are often small, nocturnal creatures. The earliest sloths were already in a good position to shift with Earth’s climate and ecological changes. The uplift of the Andes Mountains in South America led to changes on the continent as more open, drier grasslands spread where there had previously been wetter woodlands and forests. While some sloths became smaller as they spent more time around and within trees, the grasslands would host the broadest diversity of sloth species. The grasslands sloths were the ones that ballooned to exceptional sizes. Earth has been shifting between warmer and wetter times, like now, and cooler and drier climates over millions of years. The chillier and more arid times are what gave sloths their size boost. During these colder spans, bigger sloths were better able to hold on to their body heat, but they also didn’t need as much water, and they were capable of traveling long distances more efficiently thanks to their size. “The cooler and drier the climate, especially after 11.6 million years ago, led to expansive grasslands, which tends to favor the evolution of increasing body mass,” Narducci says. The combination of climate shifts, mountain uplift and vegetation changes created environments where sloths could evolve into a variety of forms—including multiple times when sloths became giants again. Gill says that large body size was a “winning strategy” for herbivores. “At a certain point, megaherbivores get so large that most predators can’t touch them; they’re able to access nutrition in foods that other animals can’t really even digest thanks to gut microbes that help them digest cellulose, and being large means you’re also mobile,” Gill adds, underscoring advantages that have repeatedly pushed animals to get big time and again. The same advantages underwrote the rise of the biggest dinosaurs as well as more recent giants like the sloths and mastodons. As large sloths could travel further, suitable grassland habitats stretched from Central America to prehistoric Florida. “This is what also allowed for their passage into North America,” Narducci says. Sloths were able to follow their favored habitats between continents. If the world were to shift back toward cooler and drier conditions that assisted the spread of the grasslands that gave sloths their size boost, perhaps similar giants could evolve. The sticking point is what humans are doing to Earth’s climate, ecosystems and existing species. The diversity and number of large species alive today is vastly, and often negatively, affected by humans. A 2019 study of human influences on 362 megafauna species, on land and in the water, found that 70 percent are diminishing in number, and 59 percent are getting dangerously close to extinction. But if that relationship were to change, either through our actions or intentions, studies like the new paper on giant sloths hint that ecosystems brimming with a wealth of megafaunal species could evolve again. Big animals change the habitats where they live, which in turn tends to support more large species adapted to those environments. The giant sloths that evolved among ancient grasslands helped to keep those spaces open in tandem with other big herbivores, such as mastodons, as well as the large carnivores that preyed upon them. Paleontologists and ecologists know this from studies of how large animals such as giraffes and rhinos affect vegetation around them. Big herbivores, in particular, tend to keep habitats relatively open. Elephants and other big beasts push over trees, trample vegetation underfoot, eat vast amounts of greenery and transport seeds in their dung, disassembling vegetation while unintentionally planting the beginnings of new habitats. Such broad, open spaces were essential to the origins of the giant sloths, and so creating wide-open spaces helps spur the evolution of giants to roam such environments. For now, we are left with the fossil record of giant animals that were here so recently that some of their bones aren’t even petrified, skin and fur still clinging to some skeletons. “The grasslands they left behind are just not the same, in ways we’re really only starting to understand and appreciate,” Gill says. A 2019 study on prehistoric herbivores in Africa, for example, found that the large plant-eaters altered the water cycling, incidence of fire and vegetation of their environment in a way that has no modern equivalent and can’t just be assumed to be an ancient version of today’s savannas. The few megaherbivores still with us alter the plant life, water flow, seed dispersal and other aspects of modern environments in their own unique ways, she notes, which should be a warning to us to protect them—and the ways in which they affect our planet. If humans wish to see the origin of new magnificent giants like the ones we visit museums to see, we must change our relationship to the Earth first. Get the latest Science stories in your inbox.

How changes in California culture have influenced the evolution of wild animals in Los Angeles

A new study argues that religion, politics and war affect how animals and plants in cities evolve, and the confluence of these forces seem to be actively affecting urban wildlife in L.A.

For decades, biologists have studied how cities affect wildlife by altering food supplies, fragmenting habitats and polluting the environment. But a new global study argues that these physical factors are only part of the story. Societal factors, the researchers claim, especially those tied to religion, politics and war, also leave lasting marks on the evolutionary paths of the animals and plants that share our cities.Published in Nature Cities, the comprehensive review synthesizes evidence from cities worldwide, revealing how human conflict and cultural practices affect wildlife genetics, behavior and survival in urban environments.The paper challenges the tendency to treat the social world as separate from ecological processes. Instead, the study argues, we should consider the ways the aftershocks of religious traditions, political systems and armed conflicts can influence the genetic structure of urban wildlife populations. (Gabriella Angotti-Jones / Los Angeles Times) “Social sciences have been very far removed from life sciences for a very long time, and they haven’t been integrated,” said Elizabeth Carlen, a biologist at Washington University in St. Louis and co-lead author of the study. “We started just kind of playing around with what social and cultural processes haven’t been talked about,” eventually focusing on religion, politics and war because of their persistent yet underexamined impacts on evolutionary biology, particularly in cities, where cultural values and built environments are densely concentrated.Carlen’s own work in St. Louis examines how racial segregation and urban design, often influenced by policing strategies, affect ecological conditions and wild animals’ access to green spaces.“Crime prevention through environmental design,” she said, is one example of how these factors influence urban wildlife. “Law enforcement can request that there not be bushes … or short trees, because then they don’t have a sight line across the park.” Although that design choice may serve surveillance goals, it also limits the ability of small animals to navigate those spaces.These patterns, she emphasized, aren’t unique to St. Louis. “I’m positive that it’s happening in Los Angeles. Parks in Beverly Hills are going to look very different than parks in Compton. And part of that is based on what policing looks like in those different places.” This may very well be the case, as there is a significantly lower level of urban tree species richness in areas like Compton than in areas like Beverly Hills, according to UCLA’s Biodiversity Atlas. A coyote wanders onto the fairway, with the sprinklers turned on, as a golfer makes his way back to his cart after hitting a shot on the 16th hole of the Harding golf course at Griffith Park. (Mel Melcon / Los Angeles Times) The study also examines war and its disruptions, which can have unpredictable effects on animal populations. Human evacuation from war zones can open urban habitats to wildlife, while the destruction of green spaces or contamination of soil and water can fragment ecosystems and reduce genetic diversity.In Kharkiv, Ukraine, for example, human displacement during the Russian invasion led to the return of wild boars and deer to urban parks, according to the study. In contrast, sparrows, which depend on human food waste, nearly vanished from high-rise areas.All of this, the researchers argue, underscores the need to rethink how cities are designed and managed by recognizing how religion, politics and war shape not just human communities but also the evolutionary trajectories of urban wildlife. By integrating ecological and social considerations into urban development, planners and scientists can help create cities that are more livable for people while also supporting the long-term genetic diversity and adaptability of the other species that inhabit them.This intersection of culture and biology may be playing out in cities across the globe, including Los Angeles.A study released earlier this year tracking coyotes across L.A. County found that the animals were more likely to avoid wealthier neighborhoods, not because of a lack of access or food scarcity, but possibly due to more aggressive human behavior toward them and higher rates of “removal” — including trapping and releasing elsewhere, and in some rare cases, killing them. In lower-income areas, where trapping is less common, coyotes tended to roam more freely, even though these neighborhoods often had more pollution and fewer resources that would typically support wild canines. Researchers say these patterns reflect how broader urban inequities are written directly into the movements of and risks faced by wildlife in the city.Black bears, parrots and even peacocks tell a similar story in Los Angeles. Wilson Sherman, a PhD student at UCLA who is studying human-black bear interactions, highlights how local politics and fragmented municipal governance shape not only how animals are managed but also where they appear. (Carolyn Cole / Los Angeles Times) “Sierra Madre has an ordinance requiring everyone to have bear-resistant trash cans,” Sherman noted. “Neighboring Arcadia doesn’t.” This kind of patchwork governance, Sherman said, can influence where wild animals ultimately spend their time, creating a mosaic of risk and opportunity for species whose ranges extend across multiple jurisdictions.Cultural values also play a role. Thriving populations of non-native birds, such as Amazon parrots and peacocks, illustrate how aesthetic preferences and everyday choices can significantly influence the city’s ecological makeup in lasting ways.Sherman also pointed to subtler, often overlooked influences, such as policing and surveillance infrastructure. Ideally, the California Department of Fish and Wildlife would be the first agency to respond in a “wildlife situation,” as Sherman put it. But, he said, what often ends up happening is that people default to calling the police, especially when the circumstances involve animals that some urban-dwelling humans may find threatening, like bears.Police departments typically do not possess the same expertise and ability as CDFW to manage and then relocate bears. If a bear poses a threat to human life, police policy is to kill the bear. However, protocols for responding to wildlife conflicts that are not life-threatening can vary from one community to another. And how police use non-lethal methods of deterrence — such as rubber bullets and loud noises — can shape bear behavior.Meanwhile, the growing prevalence of security cameras and motion-triggered alerts has provided residents with new forms of visibility into urban biodiversity. “That might mean that people are suddenly aware that a coyote is using their yard,” Sherman said. In turn, that could trigger a homeowner to purposefully rework the landscape of their property so as to discourage coyotes from using it. Surveillance systems, he said, are quietly reshaping both public perception and policy around who belongs in the city, and who doesn’t. A mountain lion sits in a tree after being tranquilized along San Vicente Boulevard in Brentwood on Oct. 27, 2022. (Wally Skalij / Los Angeles Times) Korinna Domingo, founder and director of the Cougar Conservancy, emphasized how cougar behavior in Los Angeles is similarly shaped by decades of urban development, fragmented landscapes and the social and political choices that structure them. “Policies like freeway construction, zoning and even how communities have been historically policed or funded can affect where and how cougars move throughout L.A.,” she said. For example, these forces have prompted cougars to adapt by becoming more nocturnal, using culverts or taking riskier crossings across fragmented landscapes.Urban planning and evolutionary consequences are deeply intertwined, Domingo says. For example, mountain lion populations in the Santa Monica and Santa Ana mountains have shown signs of reduced genetic diversity due to inbreeding, an issue created not by natural processes, but by political and planning decisions — such as freeway construction and zoning decisions— that restricted their movement decades ago.Today, the Wallis Annenberg Wildlife Crossing, is an attempt to rectify that. The massive infrastructure project is happening only, Domingo said, “because of community, scientific and political will all being aligned.”However, infrastructure alone isn’t enough. “You can have habitat connectivity all you want,” she said, but you also have to think about social tolerance. Urban planning that allows for animal movement also increases the likelihood of contact with people, pets and livestock — which means humans need to learn how to interact with wild animals in a healthier way.In L.A., coexistence strategies can look very different depending on the resources, ordinances and attitudes of each community. Although wealthier residents may have the means to build predator-proof enclosures, others lack the financial or institutional support to do the same. And some with the means simply choose not to, instead demanding lethal removal., “Wildlife management is not just about biology,” Domingo said. “It’s about values, power, and really, who’s at the table.”Wildlife management in the United States has long been informed by dominant cultural and religious worldviews, particularly those grounded in notions of human exceptionalism and control over nature. Carlen, Sherman and Domingo all brought up how these values shaped early policies that framed predators as threats to be removed rather than species to be understood or respected. In California, this worldview contributed not only to the widespread killing of wolves, bears and cougars but also to the displacement of American Indian communities whose land-based practices and beliefs conflicted with these approaches. A male peacock makes its way past Ian Choi, 21 months old, standing in front of his home on Altura Road in Arcadia. (Mel Melcon / Los Angeles Times) Wildlife management in California, specifically, has long been shaped by these same forces of violence, originating in bounty campaigns not just against predators like cougars and wolves but also against American Indian peoples. These intertwined legacies of removal, extermination and land seizure continue to influence how certain animals and communities are perceived and treated today.For Alan Salazar, a tribal elder with the Fernandeño Tataviam Band of Mission Indians, those legacies run deep. “What happened to native peoples happened to our large predators in California,” he said. “Happened to our plant relatives.” Reflecting on the genocide of Indigenous Californians and the coordinated extermination of grizzly bears, wolves and mountain lions, Salazar sees a clear parallel.“There were three parts to our world — the humans, the animals and the plants,” he explained. “We were all connected. We respected all of them.” Salazar explains that his people’s relationship with the land, animals and plants is itself a form of religion, one grounded in ceremony, reciprocity and deep respect. Salazar said his ancestors lived in harmony with mountain lions for over 10,000 years, not by eliminating them but by learning from them. Other predators — cougars, bears, coyotes and wolves — were also considered teachers, honored through ceremony and studied for their power and intelligence. “Maybe we had a better plan on how to live with mountain lions, wolves and bears,” he said. “Maybe you should look at tribal knowledge.”He views the Wallis Annenberg Wildlife Crossing — for which he is a Native American consultant — as a cultural opportunity. “It’s not just for mountain lions,” he said. “It’s for all animals. And that’s why I wanted to be involved.” He believes the project has already helped raise awareness and shift perceptions about coexistence and planning, and hopes that it will help native plants, animals and peoples.As L.A. continues to grapple with the future of wildlife in its neighborhoods, canyons and corridors, Salazar and others argue that it is an opportunity to rethink the cultural frameworks, governance systems and historical injustices that have long shaped human-animal relations in the city. Whether through policy reform, neighborhood education or sacred ceremony, residents need reminders that evolutionary futures are being shaped not only in forests and preserves but right here, across freeways, backyards and local council meetings. The Wallis Annenberg Wildlife Crossing under construction over the 101 Freeway near Liberty Canyon Road in Agoura Hills on July 12, 2024. (Myung J. Chun / Los Angeles Times) The research makes clear that wildlife is not simply adapting to urban environments in isolation; it is adapting to a range of factors, including policing, architecture and neighborhood design. Carlen believes this opens a crucial frontier for interdisciplinary research, especially in cities like Los Angeles, where uneven geographies, biodiversity and political decisions intersect daily. “I think there’s a lot of injustice in cities that are happening to both humans and wildlife,” she said. “And I think the potential is out there for justice to be brought to both of those things.”

Something Strange Is Happening to Tomatoes Growing on the Galápagos Islands

Scientists say wild tomato plants on the archipelago's western islands are experiencing "reverse evolution" and reverting back to ancestral traits

Something Strange Is Happening to Tomatoes Growing on the Galápagos Islands Scientists say wild tomato plants on the archipelago’s western islands are experiencing “reverse evolution” and reverting back to ancestral traits Sarah Kuta - Daily Correspondent July 9, 2025 4:29 p.m. Scientists are investigating the production of ancestral alkaloids by tomatoes in the Galápagos Islands. Adam Jozwiak / University of California, Riverside Some tomatoes growing on the Galápagos Islands appear to be going back in time by producing the same toxins their ancestors did millions of years ago. Scientists describe this development—a controversial process known as “reverse evolution”—in a June 18 paper published in the journal Nature Communications. Tomatoes are nightshades, a group of plants that also includes eggplants, potatoes and peppers. Nightshades, also known as Solanaceae, produce bitter compounds called alkaloids, which help fend off hungry bugs, animals and fungi. When plants produce alkaloids in high concentrations, they can sicken the humans who eat them. To better understand alkaloid synthesis, researchers traveled to the Galápagos Islands, the volcanic chain roughly 600 miles off the coast of mainland Ecuador made famous by British naturalist Charles Darwin. They gathered and studied more than 30 wild tomato plants growing in different places on various islands. The Galápagos tomatoes are the descendents of plants from South America that were probably carried to the archipelago by birds. The team’s analyses revealed that the tomatoes growing on the eastern islands were behaving as expected, by producing alkaloids that are similar to those found in modern, cultivated varieties. But those growing on the western islands, they found, were creating alkaloids that were more closely related to those produced by eggplants millions of years ago. Tomatoes growing on the western islands (shown here) are producing ancestral alkaloids.  Adam Jozwiak / University of California, Riverside Researchers suspect the environment may be responsible for the plants’ unexpected return to ancestral alkaloids. The western islands are much younger than the eastern islands, so the soil is less developed and the landscape is more barren. To survive in these harsh conditions, perhaps it was advantageous for the tomato plants to revert back to older alkaloids, the researchers posit. “The plants may be responding to an environment that more closely resembles what their ancestors faced,” says lead author Adam Jozwiak, a biochemist at the University of California, Riverside, to BBC Wildlife’s Beki Hooper. However, for now, this is just a theory. Scientists say they need to conduct more research to understand why tomato plants on the western islands have adapted this way. Scientists were able to uncover the underlying molecular mechanisms at play: Four amino acids in a single enzyme appear to be responsible for the reversion back to the ancestral alkaloids, they found. They also used evolutionary modeling to confirm the direction of the adaptation—that is, that the tomatoes on the western islands had indeed returned to an earlier, ancestral state. Among evolutionary biologists, “reverse evolution” is somewhat contentious. The commonly held belief is that evolution marches forward, not backward. It’s also difficult to prove an organism has reverted back to an older trait through the same genetic pathways. But, with the new study, researchers say they’ve done exactly that. “Some people don’t believe in this,” says Jozwiak in a statement. “But the genetic and chemical evidence points to a return to an ancestral state. The mechanism is there. It happened.” So, if “reverse evolution” happened in wild tomatoes, could something similar happen in humans? In theory, yes, but it would take a long time, Jozwiak says. “If environmental conditions shifted dramatically over long timescales, it’s possible that traits from our distant past could re-emerge, but whether that ever happens is highly uncertain,” Jozwiak tells Newsweek’s Daniella Gray. “It’s speculative and would take millions of years, if at all.” Get the latest stories in your inbox every weekday.

Lifesize herd of puppet animals begins climate action journey from Africa to Arctic Circle

The Herds project from the team behind Little Amal will travel 20,000km taking its message on environmental crisis across the worldHundreds of life-size animal puppets have begun a 20,000km (12,400 mile) journey from central Africa to the Arctic Circle as part of an ambitious project created by the team behind Little Amal, the giant puppet of a Syrian girl that travelled across the world.The public art initiative called The Herds, which has already visited Kinshasa and Lagos, will travel to 20 cities over four months to raise awareness of the climate crisis. Continue reading...

Hundreds of life-size animal puppets have begun a 20,000km (12,400 mile) journey from central Africa to the Arctic Circle as part of an ambitious project created by the team behind Little Amal, the giant puppet of a Syrian girl that travelled across the world.The public art initiative called The Herds, which has already visited Kinshasa and Lagos, will travel to 20 cities over four months to raise awareness of the climate crisis.It is the second major project from The Walk Productions, which introduced Little Amal, a 12-foot puppet, to the world in Gaziantep, near the Turkey-Syria border, in 2021. The award-winning project, co-founded by the Palestinian playwright and director Amir Nizar Zuabi, reached 2 million people in 17 countries as she travelled from Turkey to the UK.The Herds’ journey began in Kinshasa’s Botanical Gardens on 10 April, kicking off four days of events. It moved on to Lagos, Nigeria, the following week, where up to 5,000 people attended events performed by more than 60 puppeteers.On Friday the streets of Dakar in Senegal will be filled with more than 40 puppet zebras, wildebeest, monkeys, giraffes and baboons as they run through Médina, one of the busiest neighbourhoods, where they will encounter a creation by Fabrice Monteiro, a Belgium-born artist who lives in Senegal, and is known for his large-scale sculptures. On Saturday the puppets will be part of an event in the fishing village of Ngor.The Herds’ 20,000km journey began in Kinshasa, the Democratic Republic of the Congo. Photograph: Berclaire/walk productionsThe first set of animal puppets was created by Ukwanda Puppetry and Designs Art Collective in Cape Town using recycled materials, but in each location local volunteers are taught how to make their own animals using prototypes provided by Ukwanda. The project has already attracted huge interest from people keen to get involved. In Dakar more than 300 artists applied for 80 roles as artists and puppet guides. About 2,000 people will be trained to make the puppets over the duration of the project.“The idea is that we’re migrating with an ever-evolving, growing group of animals,” Zuabi told the Guardian last year.Zuabi has spoken of The Herds as a continuation of Little Amal’s journey, which was inspired by refugees, who often cite climate disaster as a trigger for forced migration. The Herds will put the environmental emergency centre stage, and will encourage communities to launch their own events to discuss the significance of the project and get involved in climate activism.The puppets are created with recycled materials and local volunteers are taught how to make them in each location. Photograph: Ant Strack“The idea is to put in front of people that there is an emergency – not with scientific facts, but with emotions,” said The Herds’ Senegal producer, Sarah Desbois.She expects thousands of people to view the four events being staged over the weekend. “We don’t have a tradition of puppetry in Senegal. As soon as the project started, when people were shown pictures of the puppets, they were going crazy.”Little Amal, the puppet of a Syrian girl that has become a symbol of human rights, in Santiago, Chile on 3 January. Photograph: Anadolu/Getty ImagesGrowing as it moves, The Herds will make its way from Dakar to Morocco, then into Europe, including London and Paris, arriving in the Arctic Circle in early August.

Dead, sick pelicans turning up along Oregon coast

So far, no signs of bird flu but wildlife officials continue to test the birds.

Sick and dead pelicans are turning up on Oregon’s coast and state wildlife officials say they don’t yet know why. The Oregon Department of Fish and Wildlife says it has collected several dead brown pelican carcasses for testing. Lab results from two pelicans found in Newport have come back negative for highly pathogenic avian influenza, also known as bird flu, the agency said. Avian influenza was detected in Oregon last fall and earlier this year in both domestic animals and wildlife – but not brown pelicans. Additional test results are pending to determine if another disease or domoic acid toxicity caused by harmful algal blooms may be involved, officials said. In recent months, domoic acid toxicity has sickened or killed dozens of brown pelicans and numerous other wildlife in California. The sport harvest for razor clams is currently closed in Oregon – from Cascade Head to the California border – due to high levels of domoic acid detected last fall.Brown pelicans – easily recognized by their large size, massive bill and brownish plumage – breed in Southern California and migrate north along the Oregon coast in spring. Younger birds sometimes rest on the journey and may just be tired, not sick, officials said. If you find a sick, resting or dead pelican, leave it alone and keep dogs leashed and away from wildlife. State wildlife biologists along the coast are aware of the situation and the public doesn’t need to report sick, resting or dead pelicans. — Gosia Wozniacka covers environmental justice, climate change, the clean energy transition and other environmental issues. Reach her at gwozniacka@oregonian.com or 971-421-3154.Our journalism needs your support. Subscribe today to OregonLive.com.

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