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Genetic ghosts suggest Covid’s market origins

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Thursday, September 19, 2024

Genetic ghosts suggest Covid’s market originsGetty ImagesRacoon dogs are implicated as one of the potential animals that could have been the source of CovidA team of scientists say it is “beyond reasonable doubt” the Covid pandemic started with infected animals sold at a market, rather than a laboratory leak.They were analysing hundreds of samples collected from Wuhan, China, in January 2020.The results identify a shortlist of animals – including racoon dogs, civets and bamboo rats – as potential sources of the pandemic.Despite even highlighting one market stall as a hotspot of both animals and coronavirus, the study cannot provide definitive proof.The samples were collected by Chinese officials in the early stages of Covid and are one of the most scientifically valuable sources of information on the origins of the pandemic.An early link with the Huanan Seafood Wholesale Market was established when patients appeared in hospitals in Wuhan with a mystery pneumonia.The market was closed and teams swabbed locations including stalls, the inside of animal cages and equipment used to strip fur and feathers from slaughtered animals.Getty ImagesHuanan Seafood Wholesale Market was closed in the early days of the pandemicTheir analysis was published last year and the raw data made available to other scientists. Now a team in the US and France says they have performed even more advanced genetic analyses to peer deeper into Covid’s early days. It involved analysing millions of short fragments of genetic code – both DNA and RNA – to establish what animals and viruses were in the market in January 2020."We are seeing the DNA and RNA ghosts of these animals in the environmental samples, and some are in stalls where [the Covid virus] was found too," says Prof Florence Débarre, of the French National Centre for Scientific Research.The results, published in the journal Cell, highlight a series of findings that come together to make their case.It shows Covid virus and susceptible animals were detected in the same location, with some individual swabs collecting both animal and coronavirus genetic code. This is not evenly distributed across the market and points to very specific hotspots."We find a very consistent story in terms of this pointing - even at the level of a single stall - to the market as being the very likely origin of this particular pandemic," says Prof Kristian Andersen, from the Scripps Institute in the US.However, being in the same place at the same time is not proof any animals were infected.Getty ImagesThe masked palm civet was also identified at the market and played a role in the Sars virus outbreak (which is related to the virus that caused the pandemic).The animal which came up most frequently in the samples was the common raccoon dog. This has been shown to both catch and transmit Covid in experiments.Other animals identified as a potential source of the pandemic were the masked palm civet, which was also associated with the Sars outbreak in 2003, as well as hoary bamboo rats and Malayan porcupines. The experiments have not been done to see if they can spread the virus.The depth of the genetic analysis was able to identify the specific types of raccoon dogs being sold. They were those more commonly found in the wild in South China rather than those farmed for their fur. This gives scientists clues about where to look next. Reading the virus's codeThe research teams also analysed the genetic code of the viral samples found in the market, and compared them to samples from patients in the early days of the pandemic. Looking at the variety of different mutations in the viral samples also provides clues.The samples suggest, but do not prove, that Covid started more than once in the market with potentially two spillover events from animals to humans. The researchers say this supports the idea of the market as the origin, rather than the pandemic starting elsewhere with the market adding fuel to the fire in a superspreading event.The scientists also used the mutations to build the virus’s family tree and peer into its past.“If we estimate when do we believe most likely the pandemic started versus when do we believe most likely the outbreak at the market started, these two overlap, they’re one and the same,” says Prof Andersen.In their scientific publication, the full genetic diversity of coronavirus seen in the early days of the pandemic was found at the market.Prof Michael Worobey, of the University of Arizona, said: "Rather than being one small branch on this big bushy evolutionary tree, the market sequences are across all the branches of the tree, in a way that is consistent with the genetic diversity actually beginning at the market."He said this study, combined with other data – such as early cases and hospitalisations being linked to the market – all pointed to an animal origin of Covid.Prof Worobey said: “It's far beyond reasonable doubt that that this is how it happened”, and that other explanations for the data required "really quite fanciful absurd scenarios".“I think there's been a lack of appreciation even up until now about how strong the evidence is.”Did the pandemic start here?Getty ImagesThe Wuhan Institute of Virology campus in Hubei province, China.The lab-leak theory argues that instead of the virus spilling over from wildlife, it instead came from the Wuhan Institute of Virology (WIV), which has long studied coronaviruses.It is located a 40-minute drive away from the market. The US intelligence community was asked to weigh up the likelihood of a leak – either accidental or deliberate.In June 2023, all the agencies involved said either a leak or animal origins were plausible scenarios.The National Intelligence Council and four other agencies said animals were the likely source. The FBI and the Department of Energy thought it was more likely to be a laboratory incident.Prof Andersen said: "To many this seems like the most likely scenario - 'the lab is right there, of course it was the lab, are you stupid?'. I totally get that argument."However, he says there is now plenty of data that "really points to the market as the true early epicentre" and "even locations within that market".Identifying the animals that could have been the source of the pandemic does provide clues to where scientists could look for further evidence of an animal origin.However, because farms destroyed their animals in the early days of Covid it means there may no longer be any evidence left to find."In all likelihood, we missed our chance," says Prof Worobey.Prof Alice Hughes, from the University of Hong Kong, who was not involved in the analysis, said it was a “good study”.“[But] without swabs from the actual animals in the market, which were not collected, we cannot obtain any higher certainty."Prof James Wood, the co-director of Cambridge Infectious Diseases, said the study provided “very strong evidence” of the pandemic starting in wildlife stalls at the market. However, he said it could not be definitive because the samples were collected after the market closed, and the pandemic probably started weeks earlier.And he warned "little or nothing" was being done to limit the live trade in wildlife, and "uncontrolled transmission of animal infections poses a major risk of future pandemics".

A team of scientists say it is "beyond reasonable doubt" the Covid pandemic started with infected animals.

Genetic ghosts suggest Covid’s market origins

Getty Images A mother racoon dog attending to her offspring — Racoon dogs are implicated as one of the potential animals that could have been the source of Covid

A team of scientists say it is “beyond reasonable doubt” the Covid pandemic started with infected animals sold at a market, rather than a laboratory leak.

They were analysing hundreds of samples collected from Wuhan, China, in January 2020.

The results identify a shortlist of animals – including racoon dogs, civets and bamboo rats – as potential sources of the pandemic.

Despite even highlighting one market stall as a hotspot of both animals and coronavirus, the study cannot provide definitive proof.

The samples were collected by Chinese officials in the early stages of Covid and are one of the most scientifically valuable sources of information on the origins of the pandemic.

An early link with the Huanan Seafood Wholesale Market was established when patients appeared in hospitals in Wuhan with a mystery pneumonia.

The market was closed and teams swabbed locations including stalls, the inside of animal cages and equipment used to strip fur and feathers from slaughtered animals.

Getty Images Picture showing the closed and empty Huanan Seafood Wholesale Market in Wuhan, China. — Huanan Seafood Wholesale Market was closed in the early days of the pandemic

Their analysis was published last year and the raw data made available to other scientists. Now a team in the US and France says they have performed even more advanced genetic analyses to peer deeper into Covid’s early days.

It involved analysing millions of short fragments of genetic code – both DNA and RNA – to establish what animals and viruses were in the market in January 2020.

"We are seeing the DNA and RNA ghosts of these animals in the environmental samples, and some are in stalls where [the Covid virus] was found too," says Prof Florence Débarre, of the French National Centre for Scientific Research.

The results, published in the journal Cell, highlight a series of findings that come together to make their case.

It shows Covid virus and susceptible animals were detected in the same location, with some individual swabs collecting both animal and coronavirus genetic code. This is not evenly distributed across the market and points to very specific hotspots.

"We find a very consistent story in terms of this pointing - even at the level of a single stall - to the market as being the very likely origin of this particular pandemic," says Prof Kristian Andersen, from the Scripps Institute in the US.

However, being in the same place at the same time is not proof any animals were infected.

Getty Images A masked palm civet sitting in a tree — The masked palm civet was also identified at the market and played a role in the Sars virus outbreak (which is related to the virus that caused the pandemic).

The animal which came up most frequently in the samples was the common raccoon dog. This has been shown to both catch and transmit Covid in experiments.

Other animals identified as a potential source of the pandemic were the masked palm civet, which was also associated with the Sars outbreak in 2003, as well as hoary bamboo rats and Malayan porcupines. The experiments have not been done to see if they can spread the virus.

The depth of the genetic analysis was able to identify the specific types of raccoon dogs being sold. They were those more commonly found in the wild in South China rather than those farmed for their fur. This gives scientists clues about where to look next.

Reading the virus's code

The research teams also analysed the genetic code of the viral samples found in the market, and compared them to samples from patients in the early days of the pandemic. Looking at the variety of different mutations in the viral samples also provides clues.

The samples suggest, but do not prove, that Covid started more than once in the market with potentially two spillover events from animals to humans. The researchers say this supports the idea of the market as the origin, rather than the pandemic starting elsewhere with the market adding fuel to the fire in a superspreading event.

The scientists also used the mutations to build the virus’s family tree and peer into its past.

“If we estimate when do we believe most likely the pandemic started versus when do we believe most likely the outbreak at the market started, these two overlap, they’re one and the same,” says Prof Andersen.

In their scientific publication, the full genetic diversity of coronavirus seen in the early days of the pandemic was found at the market.

Prof Michael Worobey, of the University of Arizona, said: "Rather than being one small branch on this big bushy evolutionary tree, the market sequences are across all the branches of the tree, in a way that is consistent with the genetic diversity actually beginning at the market."

He said this study, combined with other data – such as early cases and hospitalisations being linked to the market – all pointed to an animal origin of Covid.

Prof Worobey said: “It's far beyond reasonable doubt that that this is how it happened”, and that other explanations for the data required "really quite fanciful absurd scenarios".

“I think there's been a lack of appreciation even up until now about how strong the evidence is.”

Did the pandemic start here?

Getty Images Aerial view shows the campus of the Wuhan Institute of Virology, in China's central Hubei province — The Wuhan Institute of Virology campus in Hubei province, China.

The lab-leak theory argues that instead of the virus spilling over from wildlife, it instead came from the Wuhan Institute of Virology (WIV), which has long studied coronaviruses.

It is located a 40-minute drive away from the market. The US intelligence community was asked to weigh up the likelihood of a leak – either accidental or deliberate.

In June 2023, all the agencies involved said either a leak or animal origins were plausible scenarios.

The National Intelligence Council and four other agencies said animals were the likely source. The FBI and the Department of Energy thought it was more likely to be a laboratory incident.

Prof Andersen said: "To many this seems like the most likely scenario - 'the lab is right there, of course it was the lab, are you stupid?'. I totally get that argument."

However, he says there is now plenty of data that "really points to the market as the true early epicentre" and "even locations within that market".

Identifying the animals that could have been the source of the pandemic does provide clues to where scientists could look for further evidence of an animal origin.

However, because farms destroyed their animals in the early days of Covid it means there may no longer be any evidence left to find.

"In all likelihood, we missed our chance," says Prof Worobey.

Prof Alice Hughes, from the University of Hong Kong, who was not involved in the analysis, said it was a “good study”.

“[But] without swabs from the actual animals in the market, which were not collected, we cannot obtain any higher certainty."

Prof James Wood, the co-director of Cambridge Infectious Diseases, said the study provided “very strong evidence” of the pandemic starting in wildlife stalls at the market. However, he said it could not be definitive because the samples were collected after the market closed, and the pandemic probably started weeks earlier.

And he warned "little or nothing" was being done to limit the live trade in wildlife, and "uncontrolled transmission of animal infections poses a major risk of future pandemics".

Read the full story here.

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The Coyotes Arrived. Now, They’re Changing Angel Island.

Deer and raccoons that once fearlessly roamed the island, have become prey. The post The Coyotes Arrived. Now, They’re Changing Angel Island. appeared first on Bay Nature.

Just over a mile of water lies between Angel Island and the mainland town of Tiburon. During high winds and currents, kayakers tend to steer clear of this channel known as Raccoon Strait, which carries some of San Francisco Bay’s strongest and deepest waters. Nonetheless, some swimmers choose to fight the tides, including Olympians competing in the Tiburon Nautical Mile Swim, and a few furry, four-legged canines with a steadfast determination to reach an island buffet. For as long as California State Parks (CSP) staff can remember, they have never encountered coyotes on Angel Island. Then in 2017, a disbelieving ranger spotted a coyote, and then another one and another one. As the new top predator spreads across the 1.2 square mile island, the cascade of their effects on the local ecology is turning researchers’ heads. Scientists from the California Department of Fish and Wildlife (CDFW) collected data on the island this October, hoping to learn about the coyotes’ watery crossings and impact on the island deer population. “We do know coyotes have been expanding south into Marin County and to San Francisco. They’re already taking exploratory things like going across the Golden Gate Bridge,” says Brett Furnas, a CDFW quantitative ecologist. “So it’s not a stretch that they would, maybe by accident, get swept across to Angel Island, or intentionally do that.” Coyote swimming towards Tiburon from Angel Island this April, its head just barely visible (Left, Photo by Casey Dexter-Lee); Coyote getting its legs wet on the shores of Angel Island looking towards Tiburon (Right, Photo by California State Parks/Bill Miller) The idea of coyotes on Angel Island has been floated before. In 1915, the US Army introduced about 20 Columbian black-tailed deer (Odocoileus hemionus) to Angel Island for hunting, but stopped in the 1950s when the island became a state park. Over the next 50 years, the deer population exploded to as high as 300. It was the state’s highest documented density of deer—a record likely still standing in California. “The deer were starving and skinny, and there was a concern for the impacts on the island’s cultural plants and vegetation,” says Bill Miller, a CSP environmental scientist. Native plants on the island that deer are known to feed on include sagebrush, chamise, and purple needlegrass. “There were all sorts of suggestions thrown out,” says Miller. “We could relocate some. We could introduce coyotes onto the island. We could maybe introduce contraceptives.” Angel Island fawns lounging in 2010 (Matt Baume via Flickr, CC by-SA 2.0); An Angel Island doe dashing across the street (Torroid via Flickr, CC BY-SA 2.0) Relocating coyotes to Angel Island was proposed in 1981 by Dale McCullough, a wildlife biologist and former professor at UC Berkeley. He advocated for bringing over a small pack of six coyotes to prey on the sick deer and fawns damaging the island’s trees and shrubs. Native to California and most of the US, coyotes (Canis latrans) can survive almost everywhere, from dry deserts to foggy coasts. In the past fifty years, their numbers and range have expanded into sprawling cities and suburbs, where they feed on cats, small dogs, rats, trash, and fruit. McCullough’s coyote proposal, however, fell flat. Originally in favor of the plan, the California Department of Fish and Game succumbed to the backlash from the public and animal rights groups, and withdrew the proposal to naturally control the deer population with predators. “In the end, state parks went with a culling program, and over the years, it would cull deer every few years,” says Miller. “But then at some point, the culling stopped and the numbers of deer on the island apparently stabilized… Shortly after, the coyotes showed up.” Coyote perched on a rocky outcrop, and a nonchalant pair on the street looping around Angel Island (California State Parks/Michael Dolan) Parks employee Mikayla Smith first saw a coyote on the lawn of the Parks staff residences in 2017. But she was met with disbelief when Parks staff told her coyotes didn’t exist on the island. Her sighting was dismissed until another Parks employee, Andrew Luskus, caught a glimpse of one. When Luskus turned the corner on his bike along the four-mile fire trail that circles the island, he made split-second eye contact with a coyote, before it scampered into the bushes. “Are you sure it wasn’t a dog?” fellow Parks employees asked. He had seen many coyotes during his time as a Parks ranger in Death Valley—he was sure. Within a year after Luskus’ sighting, Parks staff began hearing them. Ferry workers were seeing them. “I’ve seen coyotes swim across Raccoon Strait,” wrote Ashley Kristensen, the operations manager who has worked at the Angel Island-Tiburon Ferry for 15 years. Aaron Swerkes, a fifth-year ferry captain who has sailed in the Bay for the past thirty years, has seen coyotes in the strait just a couple times since his first sighting about a decade ago. The first litter of pups appeared in 2019. And with it, a trophic cascade—a domino effect that begins when top predators impact the behavior or abundance of their prey, trickling down to the rest of the food chain. Coyote pups in a redwood grove near the southern tip of the island on June 21, 2024 (Omar Babovic)Perhaps the most famous example of a trophic cascade is the reintroduction of gray wolves to Yellowstone National Park, after they were shot, trapped, and poisoned into extinction in the 1930s. Without their top predator, elk were unafraid in the open and as a result overgrazed on young brush and trees, leaving scientists concerned about erosion and plant die-off. From 1995 to 1996, the National Parks Service released thirty-one gray wolves to prey on the elk. In just five years, willow and aspen stands recovered along riverbanks. Beavers and other wildlife began to thrive, and even the course of the river itself changed as a result. At Angel Island, a similar cascade has begun. Now a menu item, deer timidly skirt among shrubs and bushes. “Around the time the last ferry left, the deer would come and hang out on the lawn in the visitors center,” says Casey Dexter-Lee, the State Parks Interpreter II who has lived on the island for 14 years. “Now, they aren’t in this open space as much and are a bit more cautious.” While bucks remain gallivanting the streets, armed with their antlers, fawn and doe are rarer sights. Since the litter’s arrival, Parks staff have not witnessed any deer grow into adulthood, according to Dexter-Lee, though it is possible that they were raised on remote, hidden parts of the island. “I do know that coyotes are eating deer and fawn,” says Miller. “Staff have told me that, and when we were out there last week, I found a deer hoof in coyote scat.” Angel Island Parks Interpreter II Casey Dexter-Lee looking at some coyote scat on the road, and also, a buck (Jillian Magtoto) Raccoons, too, are no longer a common sight. They used to steal and beg from people, who were concerned about seeing them in the daytime, since it is usually a sign of sickness or rabies, says Dexter-Lee, Now, they’re no longer a problem. Dexter-Lee also wouldn’t mind if the coyotes kept the Norwegian rats under control, which arrived on 19th and 20th-century ships, and have since disrupted the growth of native plants and the wildlife that relies on them. Still, scientists and staff worry that one endemic species could suffer from predation: the Angel Island mole. It’s slightly larger than other East Bay moles with a broader nose, bigger feet, heavier front claws, and slightly darker coloring. “The Angel Island mole is a subspecies of mole that is only found on this island,” says Miller. “But I don’t know what their numbers are or if coyotes are eating them or not.” Raccoon in the brush of Angel Island in 2018 (l Rocky Ordoñez via iNaturalist, CC0); The pictured broad-footed mole (Scapanus latimanus) is found primarily in California and Baja California with at least 12 subspecies, including S.I. insularis on Angel Island. (Bob Dodge via iNaturalist, CC-BY-NC 4.0) As for change in island plant life, so far there isn’t any, says Dexter-Lee. But we can make some predictions. “With less grazing pressure we may see more diversity, an increase in non-resistant browse, and a denser forest with smaller and more abundant stems,” says Miller. For Angel Island, he adds, less deer may mean more oak trees. In a seemingly endless cornucopia of food options, the coyotes appear to live in an island paradise. They regularly munch the fallen fruit beneath the Catalina cherry and Canary Island date palm trees, enriching their varied omnivorous diet. Unrestricted by their crepuscular clock, they encounter visitors and staff at all hours of the day. Trails and roads are overrun by their scat. They loiter among picnic tables where visitors might leave behind crumbs. Since the first litter in 2019, Parks staff have observed small coyotes and pups every year. But the extent of their growth has limits. “There’s only so much food and space to support coyotes on an island,” says Furnas, who leads the CDFW’s investigation of coyote and deer populations on Angel Island. A coyote pounces and triumphantly snacks on an underground critter near the docks and Visitor’s Center picnic tables on Angel Island (Video by Jillian Magtoto)Since September, the CDFW has been collecting coyote scat and installing wildlife cameras to determine their genetics, diets, and movements. The island’s isolation presents a unique opportunity to learn how coyotes control deer populations in a closed environment, says Furnas. He suspects the coyotes are doing so by feeding on fawns, whose first year of survival is often the most critical limitation for population growth. Whether the coyotes seek food and partners beyond the island, however, remains unknown. “As long as there is enough food for them, do they stay on Angel Island, or do they go back to the mainland?” Furnas asks. “On islands, you can have genetic inbreeding… So for a healthy population, you’re going to want to have genetic mixing as well.” The CDFW hopes to provide deer and coyote population estimates within a year. Whether it plans to answer other questions of reproduction rates, genetic diversity, and interspecies dynamics depends on if the study continues in the future. But for now, if you find yourself gazing across Raccoon Strait from the island, mainland, or ferry, keep your eyes peeled for a coyote’s head bobbing in the water.

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Should Offshore Oil Rigs Be Turned into Artificial Reefs?

Oil rigs around the world are habitats for marine species. When they stop producing oil, should they be removed or allowed to stay?

Even before I could make out the silhouette of Platform Holly on the foggy horizon, I could see and smell oil. Ripples of iridescent liquid floated on the sea’s surface, reflecting the cloudy sky. But the oil wasn’t coming from a leak or some other failure of the rig. Milton Love, a biologist at the Marine Science Institute at the University of California, Santa Barbara, explained that it was “kind of bubbling up out of the seafloor.” Our boat, less than two miles from the central California coast, was sailing above a natural oil seep where the offshore energy boom first began.For thousands of years the Chumash, an Indigenous group native to the region, identified these oceanic seeps and their naturally occurring soft tar, known as malak, which washed up on the shore. Sixteenth-century European explorers noted oil off the coast of modern-day Santa Barbara, and in the 1870s the U.S. oil boom reached California. In the late 1890s the first offshore oil wells in the world were drilled from piers off of Summerland Beach; 60 years later the state’s first offshore oil platform was deployed to drill the Summerland Offshore Field.Since then, 34 other oil platforms have been installed along the coast, and more than 12,000 have been installed around the world. These hulking pieces of infrastructure, however, have finite lifetimes. Eventually their oil-producing capacities tail off to the point where it is no longer economically viable to operate them—that, or there’s a spill. Today 13 of California’s 27 remaining offshore platforms are what’s known as shut-in, or no longer producing oil.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.Platform Holly is among the dead platforms awaiting their afterlives. At the time of its installation in 1966, everyone knew a platform situated directly over a natural oil and gas seep was going to be a success. And for nearly five decades it was. Then, in 2015, a corroded pipeline near Refugio State Beach owned by Plains All American Pipeline cracked, spilling 142,800 gallons of crude oil into the Santa Barbara Channel. The spill killed sea lions, pelicans and perch, among other creatures; closed fisheries and beaches; and permanently severed Platform Holly from its market.Venoco, the oil company that owned Holly at the time, was not responsible, but it was bankrupted by the event. Because Holly is positioned within three miles of the coast, it was transferred into the hands of the California State Lands Commission (SLC) in 2017. The SLC is now responsible for managing the process of decommissioning the platform and determining its fate.Because Holly is already owned by the state, not an oil company, its transition could illuminate how to evaluate the fate of rigs worldwide based on science, not politics.According to platform-decommissioning consultant John Bridges Smith, a former leasing specialist with the Bureau of Ocean Energy Management who counts ExxonMobil, ConocoPhillips and Chevron among his clients, Holly and the eight other platforms whose leases are terminated or expired will be decommissioned by the end of the decade. Based on the original contracts between the oil companies and the state and federal governments, which date to the 1960s, this means the structures will have to be fully removed. In December 2023 the Bureau of Safety and Environmental Enforcement recommended that all 23 California platforms standing in federal waters be fully removed.Doing so will incur a great expense. That’s true everywhere but especially in California, where some of the platforms are in very deep water. According to one conservative estimate, completely removing all of California’s platforms would cost the responsible oil companies $1.5 billion. Smith says these companies would prefer to delay that process for as long as possible. Some environmental groups in California, meanwhile, are pushing to hold them to the speediest timeline.Platform Holly, located off the coast of Santa Barbara, Calif.Love, who has spent the past three decades studying the aquatic life that now calls southern California’s oil platforms home, would prefer a third alternative.In the decades since they were installed, the steel support structures of California’s oil platforms have become vibrant ecosystems isolated from fishing pressures—de facto marine sanctuaries. Rather than being removed, aging fossil-fuel infrastructure and its serendipitously associated habitats can be salvaged in the ocean as state-managed artificial reefs. The entire topside—the above-water portion of steel, offices and cranes—and shallow section of a rig are removed, but part of the submerged base may remain. A pathway for doing so already exists in the U.S. and has been successfully followed 573 times in the Gulf of Mexico. Similar examples can be found around the world, from Gabon to Australia. Because Holly is already owned by the state, not an oil company, its transition could illuminate how to evaluate the fate of rigs worldwide based on science, not politics.When an oil platform is decommissioned, the process goes like this: First, in a phase known as plugging and abandoning, its oil wells are filled with concrete and sealed. Next, scientists conduct an environmental review and consider the various merits and risks of different removal strategies. The results determine a platform’s final resting place, which in most cases has been in a scrap metal yard. A platform’s support structure is called its jacket—hundreds of vertical feet of woven steel that is affixed to the bottom of the ocean. Most of the time engineers will use explosives to sever a platform jacket from the seafloor. The steel is then hauled to shore for disposal and recycling. Decommissioning is considered complete when a platform has been removed down to 15 feet below the mud line and the seafloor has been returned to preplatform conditions.Most of the offshore oil platforms that have ever been built were installed in the Gulf of Mexico—more than 7,000 since 1947. More than 5,000 of those have since been removed. In the 1980s oil companies and recreational fishing associations pushed for an alternative outcome that would both be cheaper and help to bolster struggling fish populations. In 1984 the U.S. Congress passed the National Fisheries Enhancement Act, providing for the creation of the National Artificial Reef Plan, which allowed oil platform operators to donate decommissioned rigs to states as “artificial reefs.”In the following years Texas, Louisiana, Mississippi, Florida and Alabama each passed the necessary legislation and established their own State Artificial Reef Programs. These were, and still are, funded by oil and gas contributions and the interest earned on those payments. The program hasn’t replaced full removals; between 1987 and 2017 only 11 percent of all decommissioned oil platforms off Louisiana were partially removed. But in deeper waters, the story is different: of the 15 structures decommissioned in depths greater than 400 feet, 14 have been partially removed, or “reefed.”Offshore oil infrastructure in California acts as a nursery for certain fish species.When a platform is partially removed, its topside is taken to shore. To avoid creating a navigational hazard, the first 80 to 85 feet of its jacket closest to the surface are either brought ashore or laid along the sea bottom. Finally, the remaining jacket—whether it is 15 feet of steel or hundreds—is either left in place or severed from the seafloor and towed to an approved reefing site. Liability for the reefed structure gets transferred from the oil company to the state, and the oil company donates 50 percent of its cost savings (from doing a partial removal versus a full removal) to the state. This process, colloquially referred to as rigs-to-reefs, has successfully bolstered fish populations in the Gulf.Ann Scarborough Bull, a U.C.S.B. biologist who studies the ecology of offshore oil platforms and renewable energy installations, worked in the Gulf of Mexico on offshore oil and gas regulation for 14 years. She arrived in 1975, when her husband took a job in the highly profitable offshore oil industry. When it came to oil platform ecology, “the Gulf of Mexico hadn’t been studied,” Bull says. She took a job as a chief scientist for the U.S. Minerals Management Service, which has since been reorganized into the Bureau of Ocean Energy Management, and received funding to research the communities of fish and invertebrates dwelling underneath the platforms. On her frequent trips offshore, it became clear to her that the rig jackets provided habitat that was vital to the region’s economy.Lutjanus campechanus, commonly known as the northern red snapper, is one of the most frequently caught species in the Gulf’s recreational fishing industry. A long-lived apex predator, it is mostly sedentary in its adult phase and restricted to reef habitats. Until the mid-20th century, the primary fishing grounds for red snapper were off the western coast of Florida and in the waters south of the Florida Panhandle.Just as populations in the fish’s historical range were being depleted by overfishing and trawling, red snapper began to shift and expand west across the entirety of the Gulf. Thousands of oil platforms were being installed across the northwestern and north-central Gulf. Decades of research have shown that with natural reefs few and far between, red snapper were using the oil platforms as a kind of outpost, which allowed their population size to expand significantly.Imagine the Empire State Building extending up from the ocean floor, blossoming with mussels and scallops and sea anemones, providing food to legions of fish.As drilling operations multiplied, commercial and recreational reef-fishing industries grew in tandem. Surveys from the early 1980s indicated that one quarter of fishing trips were associated with oil and gas structures. “This whole society in the Gulf of Mexico grew up with two ways to make a living: one, be a fisherman, and the other, be connected with oil and gas,” Bull says.In 2001 Bull moved back to her native California, and she arrived at U.C.S.B. in 2016. Her experience studying the state’s platforms and coming to understand the surrounding politics has shown her that the differences in platform strategy between California and Louisiana are multifold. “There are factions, especially in Santa Barbara, that absolutely despise oil and gas companies,” Bull says. This animosity, she explains, makes the rigs-to-reefs process a harder sell.It’s not unwarranted. On January 28, 1969, a blowout at Union Oil’s Platform A in the Santa Barbara Channel spilled 100,000 barrels of crude oil into the Pacific Ocean. Black tar covered beaches for dozens of miles and killed thousands of birds and marine mammals. At the time, it was the largest oil spill in U.S. history.The spill prompted the first Earth Day and the creation of the U.S. Environmental Protection Agency. It also spawned numerous environmental nonprofits in the Santa Barbara region, including Get Oil Out! and the Environmental Defense Center. Development of new oil fields off the coast of California halted and didn’t resume until 1982.Then California’s first decommissionings began. In 1988 Texaco successfully removed Platforms Helen and Herman. In 1996 Chevron removed Platforms Hope, Heidi, Hilda and Hazel from the Santa Barbara coast—but not completely. The cuttings piles—gigantic mounds of rock debris, mud, and other hydrocarbon detritus discharged by the drilling process—underneath all four platforms were allowed to remain.Linda Krop, now chief counsel for the Environmental Defense Center, was then a law clerk with the organization. The group wasn’t too happy that Chevron had seemingly gotten around the obligations of its original contracts, which required full removal of its platforms and restoration of the local environment to its natural condition.“I just think it’s criminal to kill huge numbers of animals because they settled on a piece of steel instead of a rock.” —Milton Love, biologistIn the nearly three decades since, Krop has worked as an attorney holding oil companies accountable for their environmentally destructive actions. She had her greatest court victory in 2016, achieving the termination of 40 federal oil leases offshore. Krop is firmly against the prospect of reefing off California. “The fish are going to be fine if the platforms go away,” she says. “They’re not going to disappear.”In July 2023 I visited Holly with Milton Love on an especially foggy morning. After a 30-minute boat trip from the Santa Barbara Harbor, its skeletal outline began to emerge from the mist. From a distance Holly resembled a skull with barred teeth and low, hollow eyes, but up close it was an eight-story scaffolding of steel beams, pylons and old shipping containers.Holly hasn’t produced oil for a decade, but the whirring and beeping of generators and cranes was still too loud to speak over. People in construction vests milled about the upper decks, ostensibly monitoring the wells’ recent plugging procedure and shoring up the platform. Brown sea lions were flinging themselves from the ocean onto the platform’s lower decks, howling and jostling for space. Love told me that what we were seeing was only a small piece of the action. The real story, he said, was hidden below the waterline, where the mechanical noise dims and is replaced by the crackle of shrimp and fish nibbling at the reef.The platform jackets are covered in millions of organisms and provide habitat for thousands of fish. Some of California’s 27 platforms are relatively small; Holly stands in only 211 feet of water. Others, such as the Exxon-built Harmony, stand in depths up to 1,198 feet. Imagine the Empire State Building extending up from the ocean floor, blossoming with mussels and scallops and sea anemones, providing food to legions of fish. According to a 2014 paper co-authored by Love, these platforms are among the most productive marine fish habitats in the world and, per cubic meter of seafloor, are more productive than any natural reef.In 2019 the Gulf recreational fishing community took more than 50 million trips and caught 332.5 million fish. But recreational fishing off the coast of California is nowhere near as big. And because of the more than 120,000 acres of natural rock reef along the state’s coast and Channel Islands, the amount of habitat area generated by the rigs does not significantly alter the total regional habitat area or increase the carrying capacity of the fish population. In contrast, the Gulf platforms contribute 30 percent of their region’s total “reef” habitat area.Love argues that California’s platform ecosystems are vital for different reasons. After finishing his Ph.D. and landing at U.C.S.B. as a research biologist, Love received funding from the National Biological Survey; he wrote a book called The Rockfishes of the Northeast Pacific and set out to study how oil platforms functioned as fish habitats. “Most of the money has always been from the federal government,” Love says. But a “small percentage” came from Chevron and ExxonMobil.Love’s early work laid the foundations for others to research the structures as well. In a 2014 study, quantitative marine ecologist Jeremy T. Claisse, now at California State Polytechnic University, Pomona, and his colleagues revealed that along the coast of southern California, jacket habitats don’t just support millions of tunicates, barnacles, rock scallops and shrimp; they can be sites of fish production. That means many fishes living on and around the legs grow up there and may either spend the entirety of their lives at one platform or travel elsewhere, bolstering fish populations nearby.Sea anemones live on the shell mounds that form under the platform legs.Bocaccio and cowcod rockfish of southern California’s natural reefs are economically important and at one point were considered overfished. In 2006 Love found that California’s offshore oil platforms contribute 20 percent of the young bocaccio rockfish that survive each year across the species’ entire geographic range, which stretches from Alaska to Baja California. The platforms operate essentially as nurseries, he says, incubating the next generation.Mussels dominate the platform jacket in the first 40 feet of water, forming three-inch crusts around the submerged legs and beams. Barnacles and bivalves extend even deeper. When these creatures die or are dislodged by a storm, they sink to the feet of the gargantuan structures and form shell mounds up to 220 feet in diameter and rising upward of 20 feet from the seafloor. Both among the decaying shell mounds and throughout the crisscrossing beams of the platforms’ midwater sections, juvenile rockfish of the region proliferate.Trapped within these shell mounds, however, are the piles of toxic drill cuttings. Until the late 1970s, regulation to properly dispose of cuttings was fairly loose, and operators would often deposit the debris on the seafloor. In a 2001 study, surface sediments from the shell mound of Platform Hazel, installed in 1958, were found to be lethal to 50 percent of tested shrimp within 96 hours of exposure. Recently installed platforms don’t appear to have the same problem, perhaps because most cuttings must be hauled to shore. In one study, cuttings piles below platforms installed before stricter regulation were found to contain 100 times more volatile organic compounds than a newer platform, Gina, installed in 1980.Love and his colleagues wanted to know if the contamination from cuttings extended to the water column around the shell mound. In 2013 they published a paper that found California’s platforms—regardless of age—were not contaminating their associated fish populations. “We looked at fishes that live around platforms—not just Holly but throughout southern California—and compared the heavy metal concentrations with fishes of the same species on nearby natural reefs,” he says. “There was no statistical difference between what we saw.”Still, people like Krop at the Environmental Defense Center are not convinced any oil infrastructure should be allowed to stay in the ocean. “If we need to build some [more] artificial reefs, then let’s do it the right way,” she says. California has been building its own artificial reefs since 1958, when the state’s Department of Fish and Wildlife placed 20 automobile bodies in the waters of Paradise Cove off Malibu. Such artificial reefs tend to be spread over many acres in relatively shallow waters. Platform jacket reefs, in contrast, are not even technically artificial reefs and exist as habitats of extreme vertical complexity and dimension. They are smaller in area yet more productive on average.In 2003 Mark Carr of the University of California, Santa Cruz, wrote that there are few natural rock reefs at the depths of the California oil platforms and none with comparable physical characteristics. If the goal is to contribute to overall reef area, their value is “minuscule.” If, however, the intent is to preserve their unique habitats, their value is “100 percent.”Love has a more irreverent perspective on their value. “As a biologist, I just give people facts,” he says. “But I have my own view as a citizen, which is: I just think it’s criminal to kill huge numbers of animals because they settled on a piece of steel instead of a rock.”Many countries around the world are coming up on the decommissioning of their platforms for the first time. According to Amber Sparks of Blue Latitudes, a company that consults for governments worldwide regarding the environmental effects of their platform-decommissioning practices, there is no international standard for how an oil platform should be reefed.Globally, the process is often ad hoc. Off the coast of Gabon, for instance, high-biodiversity habitats underneath more than 40 active oil platforms are included in a system of marine national parks. In Malaysia, an oil platform has been converted into a resort for scuba divers. With the assistance of Chevron, Thailand established an artificial reef program and reefed seven platforms near Koh Pha-Ngan in 2020. In waters off the U.K., five platforms have been approved for partial removal, but no full platform jacket has been reefed, and no rigs-to-reef program exists. A 2017 study evaluated the possibility of transforming one U.K. rig into a hub for harvesting wave energy.When a decommissioned platform is removed, so, too, goes habitat area for sea lions and certain fish species.According to Francis Norman, managing director of the nonprofit Center of Decommissioning Australia, there is large demand from recreational fishing communities for artificial reefs—at least off the coast of Western Australia, where more than 40 platforms are stationed in shallow waters. But in the eastern state of Victoria, 23 Exxon platforms in the Bass Strait are in depths up to 525 feet—these structures are too far from land to be seen over the horizon and are not fished because of rough water conditions.Norman says Australia does not have an official rigs-to-reef program, but in 2023 Exxon applied for permits to partially remove 13 of its platforms. The company, he says, withdrew its application this summer after a wave of media reports featured criticism of partial removal.As of August 2024, all of Holly’s 30 wells were fully plugged and abandoned. Jennifer Lucchesi, executive director of the California State Lands Commission, says the facility is being “hardened” so it won’t need 24-hour staffing as it moves into “caretaker” status. Now studies of Holly’s subsurface biology are looking at the platform’s effects on its local marine environment to inform the creation of an environmental impact report, which will review the likely net outcomes of full removal versus partial removal versus no action. The “biological study” component is being prepared by Love, Bull and their colleagues at U.C.S.B.Oil companies are interested in platform reefing because of money, not fish. Partial removal is far cheaper than full removal. Reefing the California platforms instead of eradicating them would net the companies a savings of $150 million and generate $600 million for the state. (Actual costs and savings for removal are likely to exceed these projections by at least a factor of four.) Still, not a single California platform operator has applied to begin the rigs-to-reef process. Smith believes the hesitancy results from differences in policy. Legislation in the Gulf States asks for 50 percent of an oil company’s cost savings to be paid to a state in most cases; in California, it’s 80 percent. And whereas in the Gulf liability transfers to the state, in California it essentially stays with the responsible oil company. Previous attempts, in 2015 and 2017, to amend the legislation in California failed. Krop says groups like hers “would not support making the state liable,” and Smith says that would make reefing “unworkable” for the oil companies. When approached for a comment, Chevron wrote: “We are still finalizing our decision on this issue.”Smith believes the most likely outcome for California’s aging offshore infrastructure will be not full removal or partial removal but indefinite delays. Operators are supposed to submit decommissioning plans two years before a lease ends, but operators for six offshore platforms whose leases ended in 2015 still have not followed through.Oil platforms were designed to be productive for 20 to 30 years, but some are still producing oil after 45 years. No one knows how long they might stand. In one scenario, maintenance may not be properly kept up. This isn’t hard to imagine: Platform Holly fell into a state of disrepair following its operator’s bankruptcy, and ExxonMobil, a prior operator, paid millions to refurbish the platform so it could support the equipment required to plug and abandon its dormant wells.In a soon-to-be-published paper on the topic of delay, Smith discusses a worst-case scenario in which poor maintenance and corroded steel cause a platform to collapse during an earthquake or storm. A pile of steel legs, crossbeams and submerged topside offices would rest like a shipwreck on the seafloor. Most of the midwater organisms would be gone, as would those associated with the lengthy vertical water column. But Love says organisms associated with complex bottom habitats would perhaps flourish. Rockfish and lingcod would swim around the jagged, anemone-covered pieces of broken platform legs and rusted steel, past scurrying crabs, exploring their reconfigured home.In another world, you could see oil companies keeping up with maintenance indefinitely. To prevent the steel legs from rusting and collapsing, they could continue applying zinc anodes to the steel bars, allowing the zinc to rust instead of the legs. “The marine habitat will change with climate change, of course, as everywhere will,” Love says. But the sea lions would stick around on the lower decks, as would the blacksmith damselfish in the shallow waters. The platforms’ topsides, steadfast off the Santa Barbara coast, would be a reminder of an oil-ridden past.

Animals

Climate

Energy

Horse Domestication Story Gets a Surprising Rewrite

Archaeological and genetic discoveries topple long-standing ideas about the domestication of equines

The world we live in was built on horseback. Many people today rarely encounter horses, but this is a recent development. Only a few decades ago domestic horses formed the fabric of societies around the globe. Almost every aspect of daily life was linked to horses in an important way. Mail was delivered by postal riders, people traveled by horse-drawn carriage, merchants used horses to transport goods across continents, farmers cultivated their land with horsepower, and soldiers rode horses into battle.Scholars have long sought to understand how the unique partnership between humans and horses got its start. Until recently, the conventional wisdom was that horses were gradually domesticated by the Yamnaya people beginning more than 5,000 years ago in the grassy plains of western Asia and that this development allowed these people to populate Eurasia, carrying their early Indo-European language and cultural traditions with them.Now new kinds of archaeological evidence, in conjunction with interdisciplinary collaborations, are overturning some basic assumptions about when—and why—horses were first domesticated and how rapidly they spread across the globe. These insights dramatically change our understanding of not only horses but also people, who used this important relationship to their advantage in everything from herding to warfare. This revised view of the past also has lessons for us today as we consider the fate of endangered wild horses in the steppes. And it highlights the essential value of Indigenous knowledge in piecing together later chapters of the horse-human story, when domesticated horses moved from Eurasia into the rest of the world.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.The genus Equus, which includes horses, asses and zebras, originated around four million years ago in North America. Over the next few million years its members began dispersing across the Beringia land bridge between what is now Russia and Alaska and into Asia, Europe and Africa. Horses are among humanity’s oldest and most prized prey animals. Perhaps the first indisputable evidence for hunting with weapons by early members of the human family comes from horse-rich archaeological sites such as Schöningen in Germany, dating to some 300,000 years ago. The unique lakeshore environment there preserved not only the remains of a band of horses but also the immaculately crafted wood spears that humans used to dispatch them. For millennia wild horses remained a dietary staple for early Homo sapiens living in northern Eurasia. People were keen observers of these animals they depended on for food: horses featured prominently in Ice Age art, including in spectacular images rendered in charcoal on the limestone walls of France’s Chauvet Cave more than 30,000 years ago.Horses served as muses for Ice Age people, who captured their likenesses in spectacular works of art, such as the images in France’s Chauvet Cave that date to more than 30,000 years ago.Heritage Images/Getty ImagesTracking the transition from this ancient predator-prey connection to early domestication—which includes such activities as raising, herding, milking and riding horses—can be challenging. Researchers studying the deep past rarely have the luxury of written documents or detailed imagery to chronicle changing relationships between people and animals. This is especially true in the Eurasian steppes—the cold, dry, remote grasslands where scientists suspect that the first horse herders emerged, which stretch from eastern Europe nearly to the Pacific. In the steppes, cultures have long been highly mobile, moving herds to fresh pastures with the changing seasons. Their way of life left behind archaeological assemblages that can be shallow, poorly preserved and difficult to study. Indeed, much of what we know about the origins of horse domestication comes from a single, powerful scientific source: the bones of ancient horses themselves.But it wasn’t until much later that people domesticated horses, as evidenced by burials at sites such as Novoil’inovskiy in Russia dating to the early second millennium B.C.E.As an archaeozoologist, I seek to understand the origins of domestication through the study of horse bones from archaeological sites. In the early days of this kind of scientific inquiry into domestication, some researchers looked for patterns in the size, shape or frequency of these bones over time. The basic logic behind this approach is that if horses were living in close contact with people, their bones might have become more widespread or more variable in shape and size than in earlier periods, whether because people were breeding them for particular traits or because they were putting the horses to work in ways that altered the animals’ bodies over the course of their life, among other factors.Burials of horses and chariots establish that early domesticated horses were used for transport.But it turns out that looking for these types of patterns in the archaeological record is a little bit like reading tea leaves. Changes in the shape or number of horse bones found at ancient sites could be caused by any number of other things, from environmental change to shifting human diets or even sampling errors. At best, these indicators give us only an indirect way to trace the origin of herding or riding.A stronger, more scientific understanding of horse domestication began to take shape in the 1990s. Building on the work of some earlier scholars, archaeologist David Anthony of Hartwick College in New York State and his colleagues identified direct evidence for domestication in horse remains, publishing their findings in Scientific American. When horses are used by people for transportation, they sometimes develop a particular pattern of damage on their teeth from the equipment that is used to control them. This damage, known as bit wear, can often be seen on the lower second premolar of horses ridden with metal mouthpieces, or bits. Anthony and his colleagues found bit wear in an ancient horse from a Ukrainian site known as Deriyevka, which was thought to have been home to an archaeological culture known as the Yamnaya people. Although the Deriyevka horse had not been directly dated, its association with the Yamnaya culture suggested that herders in the Eurasian steppes might have been raising and riding domestic horses by the fourth millennium B.C.E. or even earlier.The Deriyevka horse seemed to tie together a number of loose threads in scientists’ understanding of ancient Eurasia. Beginning after 6,000 years ago, during a period called the Eneolithic (also sometimes known as the Copper Age), large human burial mounds known as kurgans appeared across much of eastern and central Europe and the western steppes. Over the years many archaeologists and scholars hypothesized a connection linking kurgans, the spread of Indo-European languages and the first horse domestication. Specifically, they proposed that the Yamnaya people tamed horses in the Black Sea steppes and then swept across Eurasia on horseback, bringing their burial customs and an early form of Indo-European language—which is believed to have given rise to many languages spoken today, including English. On the heels of Anthony’s discovery, this framework, known as the kurgan hypothesis, gained wide currency in academic literature and popular consciousness.Unfortunately, the Deriyevka horse was not what it seemed. A decade later direct radiocarbon dating of the remains showed that the animal wasn’t nearly as old as Anthony thought. Instead it had lived and died sometime in the early first millennium B.C.E., when domestic horses and horseback riding were already widespread and well documented. But rather than rejecting the kurgan hypothesis entirely, archaeologists continued to explore other animal-bone assemblages from the western steppes dating to around the same period, searching for horse bones to validate the idea. During this search one site in particular drew renewed interest: Botai, located in northern Kazakhstan.Botai sits some distance east of the Yamnaya homeland. Despite lacking any obvious cultural connections to the Yamnaya, Botai is also located in the western steppes, and like Deriyevka, it dates to the fourth millennium B.C.E. Most interesting, the animal-bone assemblage recovered from excavations at Botai contained huge numbers of horses. In fact, among thousands of animal bones from Botai, almost all were from horses. Working with these materials, archaeologists began to discuss the relevance of Botai’s horses to the question of early domestication.Early on, the Botai domestication debate was a spicy one. First Anthony and his colleagues suggested that the strange surface shape of some Botai teeth was also a form of bit wear, hinting that the Botai horses were ridden. Soon, though, Sandra Olsen, now at the University of Kansas, identified the same features in wild horses, meaning they could not be taken as proof of domestication on their own. Scholars also looked at contextual aspects of the Botai site, including the architectural layout, speculating that post holes and backfilled pit houses filled with organic material could be leftover traces of corrals and corral cleaning.Still, other scientists remained skeptical—for good reason. Some Botai horses were found with harpoons directly embedded in their ribs, obviously killed by hunters. An even bigger problem with connecting Botai to domestication, though, was the age and sex patterns among the animals found at the site. In a managed herd of horses, those chosen for slaughter are either very young or very old because breeding-age animals are needed to ensure the herd’s fertility and survival. Marsha Levine and her colleagues pointed out, however, that Botai’s bone assemblage consisted mainly of the remains of mostly healthy adults. Moreover, the site contained large numbers of breeding-age females, as well as some fetal and neonatal horses from pregnant mares. The slaughter of these animals would be devastating to the fertility of a domestic herd, but evidence of it is common in archaeological sites where wild animals were hunted for food.This healthy disagreement over domestication at Botai was temporarily quashed in 2009, when a high-profile publication in the journal Science brought together new evidence apparently showing that people from Botai milked and rode horses. The authors looked at the shape of the bones of horses at Botai and argued they were similar to the modern domestic horse, Equus caballus. Using emerging techniques for the study of ancient biomolecules, scientists also analyzed ceramic shards from Botai and found residues that seemed to have come from ancient horse fats. These residues, though not diagnostic of milk on their own, had anomalous isotope values, suggesting they could have originated from milk.The most important new argument, though, was that some Botai horses displayed a different kind of tooth damage that the researchers said could be more securely linked to use of a bridle. With new results from Botai strengthening confidence in the idea of horse domestication during the fourth millennium B.C.E., the kurgan hypothesis returned to paradigm status.In the decade and a half since Botai revived the kurgan hypothesis, our archaeozoological tool kit for understanding ancient horses has grown by leaps and bounds. And one by one these new techniques and discoveries have begun to erode the connections between Botai and horse domestication. In a recent study, my colleagues and I analyzed dozens of wild horses from Ice Age sites across North America. Our research showed that the key features interpreted as evidence of bridle and bit use at Botai were probably the result of natural variation rather than horse riding or horse equipment.Moreover, we now know that many other aspects of horse riding can leave a recognizable signature in an animal’s teeth and bones. Halters, saddles and harnesses can make distinctive marks. And different activity patterns, from heavy exertion to confinement, also have identifiable impacts. For instance, the pressure from mounted riding or from pulling a carriage or chariot can each cause unique problems in a horse’s vertebral column or lower limbs. Even early veterinary practices such as dentistry are sometimes visible in the archaeological record. So far none of these more reliable indicators of domestication have been found in Botai horses.Horses from the site of Botai are now known to have belonged to a wild horse species, Przewalski’s horse, that was hunted for food. Conservation efforts are currently underway to restore this highly endangered species.Sven Zellner/Agentur Focus/ReduxWe can also look to DNA for clues. Improvements in ancient-DNA sequencing now allow scientists to reconstruct partial or whole genomic sequences from archaeological remains. Analysis of DNA from ancient people and animals has yielded some rather remarkable findings, documenting, for example, the migration of Yamnaya people from eastern Europe as far east as Siberia and Mongolia during the late fourth millennium B.C.E. These same techniques have shown no evidence of interaction between Yamnaya people and Botai, however.Likewise, new techniques for recovering ancient proteins from human dental plaque have shown no evidence of horse milk in the diet of the people who lived at Botai. In fact, horse milk apparently didn’t become widespread in western Asia until the first millennium B.C.E., 3,000 years after the Yamnaya and Botai.The most devastating blow to the kurgan hypothesis came accidentally from a 2018 genomic study by Charleen Gaunitz of the University of Copenhagen, Ludovic Orlando of the Center of Anthropobiology and Genomics of Toulouse in France and their colleagues that showed Botai horses were not the ancestors of domestic horses at all. Rather they were members of another horse species that still survives today, known as Przewalski’s horse. Przewalski’s horse is a close relative of domestic horses but one that has never been managed as a domestic animal in recorded history.Recent archaeological and genetic insights into horse domestication have relevance for understanding the horse human relationship today. Discoveries of an ancient saddle and other tack in Mongolia show that steppe cultures helped to invent technology that is still in use.Some scientists remain convinced that Botai has some connection to early domestication but now suggest that the site represents an earlier, failed effort at taming and control of Przewalski’s horse. In their 2018 study, Gaunitz and her colleagues went so far as to argue that modern Przewalski’s horses might be the escaped descendants of domesticated Botai horses, a conclusion that many others in the scientific community felt was unsupported.The Botai debate has had important real-world impacts for Przewalski’s horse. In the 20th century Przewalski’s horses went extinct in the wild, and zoo populations dwindled almost to the single digits. In recent decades these horses have returned from the brink through a careful captive-breeding program, and they have been reintroduced into some areas of Central Asia. This past June a new band of Przewalski’s horses from the Prague Zoo was released into the grasslands of central Kazakhstan, marking the first return of this species to the region in two centuries.In the long term, the success and funding of such conservation projects may hinge heavily on public support, making it imperative to get the story straight. Media attention around Botai has sometimes generated headlines suggesting that Przewalski’s horses “aren’t wild after all” and are instead domestic escapees. Narratives like these are no longer supported by the archaeological data and can imperil ongoing protection, conservation and restoration of habitat for this highly endangered species.Despite some lingering controversy over Botai, the available data emerging from new scientific approaches to studying the past paint a much clearer picture of horse domestication than we’ve ever had before. The recent spate of genomic sequencing and radiocarbon dating of horse bones from across Eurasia has all but disproved the kurgan hypothesis. Such data show us that important cultural developments in the fourth millennium B.C.E.—including the Yamnaya migration and the dissemination of kurgans and Indo-European culture—probably took place many centuries before the first horses were domesticated, aided by the spread of other livestock such as sheep, goats and cattle and the use of cattle to pull wagons. Meanwhile many steppe people still hunted wild horses for meat.New genomic analyses led by Pablo Librado of the Institute of Evolutionary Biology in Barcelona and Orlando indicate that the ancestors of modern domestic horses originated in the Black Sea steppes around 2200 B.C.E., nearly 2,000 years later than previously thought. Although we do not yet know exactly the details of their initial domestication, it is clear based on the timing that these horses belonged to post-Yamnaya culture. Patterns in the ancient genomes suggest that in the early centuries of domestication, the horse cultures of the western steppe were selectively breeding these animals for traits such as strength and docility.Horses have figured prominently in the traditions and values of the Lakota and many other Native Nations across the Great Plains and Rockies.Courtesy of the Global Institute for Traditional SciencesThis revised timeline for horse domestication is part of a growing body of evidence that casts the Yamnaya legacy in a new light. Early Indo-European cultures such as the Yamnaya are sometimes portrayed in popular culture in a nationalist manner, with links drawn between their supposed domestication of the horse, impressive transcontinental migrations, and cultural dominance. Now science indicates that the Yamnaya probably didn’t domesticate horses at all, and their migrations were not necessarily heroic conquests. For example, new genomic data show that by around 5,000 years ago Yamnaya migrants reached as far as central Mongolia, where they are known as the Afanasievo culture. Although these migrants may have helped spread sheep, goats and cattle into East Asia, initially it seems their impact was limited to a few mountain regions of the eastern steppe. After the Yamnaya arrival, it would be almost 2,000 years before horses showed up in the region. And genomic analyses suggest that their Afanasievo descendants had little lasting genetic effect on later populations.The revelation that people domesticated horses much later than previously thought resolves what was always a nagging problem with the kurgan hypothesis. If horses were domesticated in the Eneolithic, why did it take centuries for much of their impact to show up in the archaeological record? Under the kurgan model, researchers often framed horse domestication as a gradual development to explain why it took so long for horses to move beyond the steppes and revolutionize trade and conflicts, for instance. When we look at our records of the past with this revised time frame for horse domestication in mind, there appears to be the rapid, disruptive and dynamic development we expected to see after all.In our new understanding it seems that almost as soon as people tamed horses, they began using them for transport. Some of the earliest robust archaeological evidence of horse domestication comes from burials of horses paired with chariots dated to around 2000 B.C.E. at sites associated with Russia’s Sintashta culture. Radiocarbon-dating and genetic records show that within only a few centuries domestic horses spread over huge swaths of the Eurasian continent. In some cases, their expansion was peaceful: as availability of horses grew across the steppes, new people incorporated horses, herding and transport into their way of life. In other instances, domesticated horses reached new locales through destructive conquests by marauding charioteers. Some cultures riding this wave of horse-drawn expansion were Indo-European; others weren’t.A nomadic family corrals livestock on horseback in Central Mongolia.Timothy Allen/Getty ImagesBy the middle of the second millennium B.C.E., horsepower had reached civilizations from Egypt and the Mediterranean to Scandinavia in the north and Mongolia and China in the east. In many cases, the arrival of horses upended the balance of power. For example, when horses first arrived in China during the late Shang dynasty, around 3,200 years ago, they were mostly a novelty for the elite. But within little more than a century a rival power, the Western Zhou, was able to marshal its strength and skill in chariotry to bring a dramatic end to Shang rule. In very short order, horses went from being a steppe curiosity to the foundation of authority for one of the largest civilizations of East Asia.In addition to clearing up these early chapters of the human-horse story, scientific archaeology has also uncovered connections between the horse cultures of the distant past and our world today. Archaeological discoveries and genomic data from the steppes and deserts of Central Asia are revealing the ways that horses and horseback riding helped humans form networks, trade routes and empires linking the ancient world in new ways.On horseback, people traveled steppe networks and the Silk Roads to move goods, plants, animals, ideas and even early pandemic diseases across Eurasia and beyond. These emerging transcontinental connections can be directly observed in the archaeological record. In Mongolia, a royal tomb from the early steppe kingdom of the Xiongnu dating to somewhere around 100 B.C.E. was found to contain a silver plate with a picture of the Greek demigod Hercules on it. Historical records document expeditions from China to Central Asia’s Ferghana Valley in search of horses, an early step in the formation of the Silk Roads trade routes, and during the height of the Tang Dynasty, a thriving trade sent horses from the Tibetan Plateau and the Himalaya to lowland China in exchange for tea. Recent DNA sequencing of the plague-causing bacterium Yersinia pestis suggests that the earliest strains of the virus that devastated Europe first emerged deep in deserts, mountains and steppes of Central Asia before spreading along the horse-powered steppe corridors and Silk Roads in the early 14th century.The corridors and connections that ancient equestrians forged persist today: Ancient travel routes across the Mongolian steppe are now receiving makeovers with Chinese financing to serve as high-speed highways for motor vehicle transit. Even the state highway I take for my daily commute in Boulder, Colo., got its start as a 19th-century postal road.New archaeology discoveries show that steppe cultures helped to invent or spread important technologies that improved control over horses and are still used today. In Mongolia, my collaborators and I have discovered immaculately preserved ancient tack from some 1,600 years ago. This riding technology, which includes a wood frame saddle and iron stirrups, shows that steppe cultures helped to develop these equestrian devices, which gave riders greater seat stability and the ability to brace or stand in the saddle—significant advantages when it came to mounted warfare. These tools became a standard part of horse equipment in cultures all over the world, from the caliphates of Islam to the Viking explorers of the high Arctic.Archaeological science also allows us to trace the spread of domesticated horses out of Eurasia as people transported them to such places as the Sahel savanna of Africa, the Great Plains of North America, the Pampas of South America, and even island nations of Australasia and the Pacific, where horses shaped cultures across more recent periods. This work is showing some surprising results.Recently I worked with a large team of scientists, scholars and Indigenous knowledge keepers to see what archaeology, genomics and Indigenous knowledge systems could tell us about the history of domesticated horses in the U.S. The prevailing view among Western scientists was that Native American peoples did not begin caring for horses until after the Pueblo Revolt of 1680, when Pueblo people in what is now New Mexico overthrew Spanish colonizers. Through our collaboration we found that Native nations from across the Plains and Rockies adopted horses at least a century earlier than was ever chronicled in European historical records. This finding confirms perspectives preserved in some oral traditions and Tribal histories and mirrors our scholarship from similar archaeological contexts in Patagonia.Many Indigenous horse cultures, for whom a connection with horses is a source of strength, resilience and tradition, are now drawing on collaborative and interdisciplinary archaeological scholarship in their efforts to correct narratives, conserve traditional horse lineages and secure a place for horses in our changing world.In many ways, the disappearance of horses from daily life in the past century has been as rapid and jarring as their initial domestication 4,000 years ago. In most corners of the world speedy mechanization has replaced trails with pavement and horse transport with engine-powered or electric alternatives. These days, along the Front Range of the Rockies, people wearing jeans and cowboy hats once designed for life in the saddle are more likely to be found shopping at Whole Foods than slinging lassos.But the threads linking our ever changing present to the distant past are never far if you know where to look. Resolution of some of the most urgent problems of the 21st century—from saving endangered species to conserving cultural knowledge and traditions—will require a clear-headed and scientifically grounded understanding of the millennia-long relationship between human and horse.

Animals

Conservation

Culture

Rice University student awarded prestigious Rhodes Scholarship

16 committees across the U.S. selected the recipients of the Rhodes Scholarship in a competitive process. Nearly 3,000 students applied, with 865 endorsed by 243 colleges and universities, according to Rice University. In total, 238 were chosen as finalists and a group of 32 students from the United States were awarded the scholarship.

Rice UniversityJae KimA Rice University student was named one of 32 U.S. recipients of the prestigious Rhodes Scholarship — and the only Texas student to receive the award this year. The full-time scholarship program from the Rhodes Trust is a world-renowned and fully funded postgraduate award that enables talented students to study at the University of Oxford. Sixteen committees across the U.S. selected the recipients of the Rhodes Scholarship in a competitive process. Nearly 3,000 students applied, with 865 endorsed by 243 colleges and universities, according to Rice University. In total, 238 were chosen as finalists and a group of 32 students from the United States were awarded the scholarship. The scholarship was established in 1902 through the will of Cecil Rhodes. Applicants are chosen by their academic excellence, according to Rice University. Jae Kim, a senior majoring in Integrative Biology, is the university’s 13th recipient of the scholarship. He is the founder of Hermes Free Telehealth — a student-run nonprofit organization that connects clinicians to underserved patients. He was chosen to study at the University of Oxford in England next fall. “I want to become a physician but work at the forefront of climate policy,” Kim told Houston Public Media. “Just bring to the world’s attention [to] how human health and the natural environment are interconnected.” In 2025, Kim will spend two years at the University of Oxford while he pursues dual Master of Science degrees in environmental change and management, and evidence-based social intervention and policy evaluation. Kim credits his leadership experience, his time working in the community and his ambitious career goals for aiding him in the scholarship application process. “I only found out about it last year and I applied because you miss all the shots you don’t take, but it just seemed so unthinkable and out of reach so I think I’m still shocked, but I was incredibly honored that I was able to get this scholarship,” Kim said. He was born in Korea and grew up in New York City, attributing his success to opportunities he had in Houston and Rice University — where he interned at the Harris County Office of Sustainability through the Leadership Rice Mentorship program. He said his most memorable experiences were the summers he spent volunteering and conducting conservation projects at a wolf sanctuary in Colorado. “Every time I go, it just reminds me that I’m connected with the natural world and all the animals and plants and ecosystems that are on this planet, and it just reaffirms my desire to pursue a career where I can help,” Kim said. The U.S. recipients of the scholarship will join an international group of students chosen from more than 70 countries around the world. The trust, with scholarships averaging $75,000 per year, covers all college and university fees. Kim said he could have applied to study in Oxford outside of the scholarship, but the network of people across the discipline of Rhodes opened opportunities for him. “I could have applied to Oxford from outside of the Rhodes scholarship and pursued the master’s degrees regardless, but just the network of amazing people across the discipline that the Rhodes scholarship opened up to me, being able to connect with them personally,” he said. “Just gaining a global perspective on the issues I care about is exciting to me.” Lucio Vasquez contributed to this report.

Animals

Climate

Conservation

Climate Change Is Altering Animals' Colors

Lizards in France have grown lighter in color and so are many insects and birds across the globe. The effects of a changing climate are plainly visible throughout the animal kingdom

Zebras, a children’s tale goes, became striped after “standing half in the shade and half out of it.” While the author, Rudyard Kipling, wasn’t a biologist, his story may hold some truth: research shows that when temperatures rise, animals become lighter in color, resembling the sun-exposed parts of the storybook zebra. In the humid shadows, meanwhile, darker hues prevail.As our planet warms up and rain patterns shift, the feathers and skin of many species are changing colors, often getting lighter. Snails in the Netherlands are going from brown to yellow. In a species of tropical bee in Costa Rica, the proportion of orange to blue individuals is increasing. Lizards in France are turning lighter, and so are many insects and birds across the globe. “Under global warming one would expect that the darker species, and darker individuals, might decline,” says Stefan Pinkert, an ecologist and evolutionary biologist at Yale University.There are two main ways in which animal skin, fur and feathers are colored. Some of the hues we perceive are from the interaction of light with the microstructure of feathers or scales—think of a hummingbird that changes color depending on the angle at which you spot it. Others are caused by pigments, molecules that absorb light, such as carotenoids, which produce yellow, red and orange colors, and melanins, responsible for black, gray, brown and rustlike hues.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.Melanins, the most common pigments in birds and mammals, may be affected by rising temperatures and changing rain patterns. “If you have more melanin in your skin or your fur or feathers, then it tends to absorb more heat,” says Matthew Shawkey, an evolutionary biologist at Ghent University in Belgium. This may be a disadvantage as the temperature soars, he says, because it can cause animals to overheat. On the flip side, if it rains more, pathogens tend to thrive. In such conditions, dark melanins can be protective because they “toughen up tissues,” Shawkey says.A rule proposed by Charles Bogert, an American herpetologist, in a 1949 paper, predicts that hotter climates should have a higher presence of ectotherms, or so-called cold-blooded animals, that are lighter in color and therefore less likely to overheat. (These animals, such as reptiles and insects, can’t regulate their own body temperature, and they rely on external heat sources.)In recent years, science has not only confirmed Bogert’s rule but also extended it to endothermic, or warm-blooded, species. It’s not just frogs, toads, snakes and midges that are lighter in warmer regions; birds get lighter as well. A 2024 analysis of more than 10,000 species of birds showed that in hot places, white and yellow feathers win over blue and black ones.With global warming, some animal populations are becoming even lighter. Between 1967 and 2010, as temperatures in the Netherlands rose by 1.5 to two degrees Celsius, brown land snails gave way to yellow ones. Between 1990 and 2020 in the U.K., dragonflies and damselflies got progressively lighter, too—as Pinkert and his colleagues found in a 2023 paper. And if you’ve looked closely at some dragonflies, you may have noticed that they now have fewer dark ornaments on their wings.In one recent study conducted in North America, male dragonflies from 10 different species had the smallest melanin-based color patches on their wings in the warmest years between 2005 and 2019. In this same time period, pretty spots also seemed to pale on Mediterranean Blue Tits—tiny birds with yellow chests and azure, hatlike markings on their head. Between 2015 and 2019, the blue head patches of tit populations around Montpellier, France, have gotten lighter by approximately 23 percent—a change related to the rise in local temperatures.Experiments confirm the observational data: hot temperatures make animals turn lighter. In some cases, an individual may simply produce more or less pigment depending on temperature. Vivid dancer damselflies, for instance, can change their colors from dark to light and back to dark as mercury fluctuates throughout the day. Male chameleon grasshoppers go from black at 50 degrees Fahrenheit (10 degrees C) to turquoise at more than 77 degrees F (25 degrees C). “If you raise many different species of insects in cold temperatures, they develop darker, and if you raise them in warmer temperatures, they get lighter,” says Kaspar Delhey, an evolutionary biologist at the Max Planck Institute for Biological Intelligence in Seewiesen, Germany.Such effects are not limited to insects. Field experiments conducted in Spain showed that vultures that hatch in nests exposed to more sunlight have paler feathers than those that grow in more sheltered sites. It wasn’t simply that the birds were sun-bleached—the melanin in their plumage wasn’t degraded, as it would be if destroyed by sunshine. There was simply less of it to begin with.Besides individual ability to adjust color based on temperature, animal populations living in warming regions may become lighter simply because paler animals move into new areas. There may be genetic changes at play, too, Pinkert says, but we still have “a critical knowledge gap” about how such evolution may be playing out.While Bogert’s rule appears straightforward in regions that heat up yet remain dry, such as the Mediterranean, if rainfall increases alongside temperatures, species may turn dark instead of light. In 1833 Constantin Gloger, a German ornithologist, suggested that in humid places feathers are more likely to be black than white. One reason may be camouflage. In wet habitats, “there is more vegetation; the backgrounds are darker, and so a darker animal might be more camouflaged,” Delhey says. Another explanation for Gloger’s rule may be protection against pathogens, which often flourish in humid climates. A 2020 study of 16 bird species showed that feathers containing more melanin are better at resisting damage by nest bacteria. “The goal of this molecule is to protect the organism against various sources of stress. For instance, the feathers which are black are stronger,” says Alexandre Roulin, an evolutionary biologist at the University of Lausanne in Switzerland, who was not involved with the study. Research suggests that melanin molecules may not only inhibit parasites but also reinforce cells, creating a barrier against pathogens.When Delhey tested what happens when both temperatures and precipitation increase with climate change, he found that, at least in birds, “the effects of humidity are generally much, much stronger,” he says. Delhey and his colleagues mapped the plumage colors of all species of passerine birds, of which there are more than 5,000, to climates in which they live. They found that the animals were lighter where warm and dry but darker where warm and humid. Roulin and his colleagues found something similar in a 2024 study of thousands of museum specimens of barn owls collected across the globe between 1901 and 2018. The researchers showed that over time, plumage colors became lighter where the climate got warmer and drier but darker where both temperature and precipitation increased. “Where the climate change was stronger, the change in color was stronger,” Roulin says.Yet changes in precipitation patterns caused by global warming are less straightforward than a future increase in temperatures. This is why, Delhey says, if he were to predict a general trend across animals, “based on the effects of temperature, they should get lighter.” Cold-blooded animals, such as insects, may also respond more strongly to heat rather than humidity, he says, yet research on this is still lacking.Overall, shifts in animal coloration are expected to be subtle. “We are not going to see such a dramatic change that we’re not going to recognize species,” Delhey says. From a biological perspective, however, “that small difference may mean whether a species can survive,” he says. Meanwhile the animals that do adapt by changing their colors can serve as a visual reminder of humanity’s giant environmental footprint that has unsettled the entire planet. “You can track with your eyes what is the impact of climate change,” Roulin says.

Animals

Climate

Suggested Viewing

A Year With Northern Owls

We follow five North American owls in different seasons; from summer heat to spring rejuvenation.

Animals

Conservation

Documentary

When Worlds Collide: A Formosan Black Bear's Deadly Dance with Civilization

This is the true story of one Formosan black bear’s encounter with civilization. A fateful encounter with a wild boar trap in mid-autumn 2019 first brought this bear to national attention. However, after months of recuperation and subsequent release back into the wild, it lingered worryingly near settled areas, damaging orchards and even ransacking a mountain cabin in search of food. Re-released in a remote forested area, the bear set out an incredible journey across arduous terrain in the direction of home. This is the moving story of “711” … also known as “568” – a wild Formosan black bear from Taichung’s Mt. Daxue area. The bear died on the 25th day of its long journey home in May 2022 in the Mt. Wujie region of Nantou County. News of the death was a devastating blow to the hundreds involved in 711/568’s rescue, recovery, and tracking efforts. It also offered a difficult lesson for us all about the work yet ahead for wildlife conservation. This film examines Formosan black bear conservation from multiple perspectives, including those involved in this bear’s rescue and care, living in areas affected by 711/568, and working in the many public and private organizations dedicated to the cause of wildlife conservation. We hope the story told here helps further raise public understanding and concern for wildlife conservation in Taiwan.

Conservation

Inspirational

Animals

Waterfall Birds

In a place in Egypt that is close to Cairo, however, most people do not know it. The filmmaker went on a Nile cruise to discover the waterfalls world and their islands. At this place, she started a very interesting hobby called birdwatching. This hobby makes her identify different types of birds that are not known among the public.

Animals

Education

Student

Dipsas Speaks

Dipsas Speaks is a poetic reflection on the human-wildlife conflict in the Andean Amazon cloud forest of Ecuador, one of the most biodiverse places on the planet. Dipsas klebbai, a snake, observes changes in her world. 100% wildlife cast.

Forests

Conservation

Animals

Silent Forests

Loss of more than half the central African forest elephant population to poaching in the last decade has led to a concerted effort to save those that remain. These efforts are explored through one of Cameroon’s first female eco-guards, a grassroots wildlife law enforcement group, a Congolese biologist studying elephant behavior, a reformed elephant poacher, and anti-poaching sniffer dogs led by a Czech conservationist, all fighting corruption despite a lack of funding that threatens to derail their work to save the elephants.

Animals

Conservation

Documentary

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Genetic ghosts suggest Covid’s market origins

Genetic ghosts suggest Covid’s market origins

Reading the virus's code

Did the pandemic start here?

Related News

The Coyotes Arrived. Now, They’re Changing Angel Island.

Should Offshore Oil Rigs Be Turned into Artificial Reefs?

Horse Domestication Story Gets a Surprising Rewrite

Rice University student awarded prestigious Rhodes Scholarship

Climate Change Is Altering Animals' Colors

Suggested Viewing

A Year With Northern Owls

When Worlds Collide: A Formosan Black Bear's Deadly Dance with Civilization

Waterfall Birds

Dipsas Speaks

Silent Forests

Join us to forgea sustainable future

sign up for our mailing list to stay informed on the latest films and environmental headlines.

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a sustainable future