Wednesday, September 1, 2021

3546. Drought? This Is What Climate Change Looks like in the West

By Karyn Stockdale, Audubon.org, August 24, 2021 


Living back East for a few years, I missed the expansive bright blue skies of the Rockies. Now that I’ve returned to the West, I’m remembering the smoky haze that fills the sky. I’m remembering how the smell of summer has turned into the smell of smoke from wildfires. How the ash from fires hundreds of miles away sometimes coats your car and porch furniture. But it’s getting worse.

I’m used to the seasonality of streams—the spring runoff that slows to a trickle with hot summer days. My kids would wait for the monsoon storms to bring back the water flowing to our arroyo. But it was shocking to see how low the rivers and streams got so early this year. Recently, some southwestern states have seen abundant monsoonal rainfall, with some intense flooding. But in Utah, Nevada, California, and parts of the Northwest, the dryness and record-setting heat waves have intensified large wildfires. The combination of drought and heatwaves are pushing birds to their limits, leading to lethal dehydration.

Welcome drought.

There's a lot to unpack in that word. Decades of drought in the West seems to be hitting a tipping point, garnering national attention. More and more, people are recognizing this isn’t just a drought. This isn’t temporary.

It’s fires, it’s decreasing water supplies, it’s air quality issues, it’s high temperatures, and unpredictable weather. It’s an era of extremes.

This summer has turned into the worst water year for many farmers and ranchers, for wildlife managers, for businesses and communities concerned about their water supplies. We urgently need to adapt and better prepare for constant drought and for extremes to become more common. As my colleague said recently, “This is climate change stealing your water.”

Climate change is increasingly impacting all of us—threatening the health of millions of birds, our food supplies and economies, our air quality, and the water security for all of us. It’s starting to affect our way of life.

And this affects birds. The future of several bird species, including some protected by the Endangered Species Act, is tied to the health of rivers and lakes. We’ve already lost too many wetlands and riparian habitats across the West and birds are pushed to congregate in high concentrations in the last places left with water. You might recall the death of 40,000 ducks from avian botulism last year due to overcrowded conditions with limited water and habitat left at the Lower Klamath National Wildlife Refuge.  

How bad is this drought? 2021 is shaping up to be the driest year in the last century.

Everywhere in the West we see signs of the ongoing megadrought. Here are a few indicators that we are concerned about at Audubon:

  • Lake Mead, the largest reservoir on the Colorado River (and in the country), has officially reached its lowest water level in history—and it’s expected to continue dropping.
     
  • Great Salt Lake reached its lowest lake level ever recorded, and will continue to drop this year, maybe even by a foot more.
     
  • Years of reduced inflows, along with drought and a warming climate, continue to shrink the Salton Sea in California, impacting the health of surrounding communities and the available habitat and food sources for migratory birds.
     
  • Our last remaining wetlands in California’s Central Valley—essential Pacific Flyway habitat for waterfowl—are expected to receive only about 57% of their water supply.
     
  • In rural Arizona, unlimited groundwater pumping (80% of the state has no groundwater management!) is causing wells to go dry and further stressing flows in rivers and streams.
     
  • The Klamath River Basin’s drought is testing everything:  There's not enough water to meet all the demands from farmers, tribes, and wildlife, including endangered fish.
     
  • The Southwest’s other major river basin—the Rio Grande—is also historically dry.

At Great Salt Lake, the 17 named islands that usually exist on the lake, where nesting birds are protected from predators, are now peninsulas. In this “Year of the Shorebird” as designated by Utah’s Governor, the decreased water coming into the shrinking lake is affecting the whole ecosystem with potentially hemispheric implications. Great Salt Lake and its surrounding wetlands create vital habitat in the Western Hemisphere for millions of breeding and migrating shorebirds including more than 56% of the global population of American Avocets and nearly 30% of the global population of Wilson’s Phalaropes. If nothing is done to reverse course, Great Salt Lake risks suffering the fate of other large, saline lakes around the world, the loss of which invariably triggers dramatic harm to communities, local business, and human health.

In the West, we are used to competing demands for scarce water for farms, cities and rural communities, hydropower, recreation, and the environment (typically last in consideration) which can lead to conflict. Audubon’s Western Water team continues to push for all of us to face these risks and plan for water shortages with a changing climate in mind.

I keep thinking of that folk song “It Ain’t Gonna Rain No More” from my childhood. My extended family lived through the Dust Bowl in Texas and Oklahoma and went into dryland ranching. This year doesn’t feel like business as usual—it feels like the cusp of another Dust Bowl.

New approaches are needed to adapt to, respond to, and mitigate the compounding and extreme risks of climate change to communities, economies, ecosystems, and the water resources that support them.

This is why Audubon is working in state capitals and in Washington, D.C. to advocate for sensible policies and funding that benefit birds and communities alike. We have worked to ensure that the needs of birds and habitat aren’t carved out of policy decisions and water management.

Audubon is also working to secure water to enhance habitats where water is most needed. Working with partners, we continue to enable and secure water flows in rivers in places like Colorado, New Mexico, Utah, California, and Arizona. And through our science, we are improving our understanding of the long-term health of priority places for birds and how we might better manage the limited water availability into the future. 

With drought conditions persisting now into a third decade and climate change increasingly impacting water supplies and habitat in the West, we urgently need inclusive and equitable long-lasting water solutions for climate resilience. Please join us in advocating for policies, funding, and on-the-ground actions that result in sustainable change.

Monday, August 30, 2021

3545. An Interview with Louis Proyect

By Johna Walters and Louis Proyect, Jacobin, August 28, 2021


Louis Proyect, a lifelong socialist and influential online commentator known for his acerbic polemics, died this week at the age of seventy-six.

Proyect joined the Socialist Workers Party in New York City in 1967. He left the organization a decade later, rejecting what he saw as its sectarianism. During the 1980s, he found a new political home in the Central America solidarity movement, eventually becoming a key leader of the organization Technical Aid for Nicaragua, or TecNica.

TecNica’s mission was to organize delegations of skilled workers — especially computer programmers — who would travel from the United States to Nicaragua to provide technical assistance to the revolutionary state.

In addition to being a committed socialist, Proyect was also an accomplished computer programmer, having begun working in the field in 1968, during the early days of mainframe computing. He soon assumed a leadership position in TecNica and in other solidarity movement organizations, recruiting hundreds of skilled workers to the project and even establishing connections with revolutionary movements beyond Nicaragua — including in Cuba, South Africa, and Namibia.

Proyect left the solidarity movement in 1991 and became a pioneer in internet self-publishing, establishing an influential mailing list and moderated forum (MarxMail) which attracted an audience of thousands of Marxists all over the world.

As a writer, Proyect earned a reputation as being both caustic and prolific — a combination that sometimes alienated him from others on the Left. He was reflexively skeptical of writers who, he felt, indulged the frivolous or self-aggrandizing conventions of the liberal left, and was insistent in his calls for a coherent and pragmatic revolutionary strategy in the twenty-first century.

I contacted Louis in September 2019, when I was working on a PhD dissertation about international solidarity and the Nicaraguan revolution. Four years earlier, he had published an incredulous polemic responding to an article of mine in Jacobin (“What the fuck is [Walters] talking about?” he wrote), and so I was surprised when he responded immediately and graciously volunteered to talk.

I arranged to meet Louis in Washington Square Park a few weeks later. We sat on a bench for almost an hour, discussing TecNica, international solidarity, and Louis’s life on the Left. When he rose to leave, he handed me a folder containing hundreds of pages of old solidarity movement newsletters. “I think these will be very helpful for your research,” he told me. (He was right.)

Below is a transcript of our conversation together.

JW: How did you become involved with TecNica?

LP: In 1981 or so, I connected with a guy named Peter Camejo. He had been a leader of the Socialist Workers Party (SWP) in the United States. But while on a delegation to Nicaragua he came to the conclusion that the SWP was a sectarian cult.

I also remember reading an article by Leslie Gelb on the op-ed page of the New York Times. He said the United States was on a collision course with Central American guerrillas, that it could be another Vietnam. And then I would read the Militant [a newsweekly published by the SWP], and there would be nothing about Central America except empty bombast about how countries had to follow the Cuban model.

I joined CISPES [Committee in Solidarity with the People of El Salvador], which was a pretty vibrant organization at the time. I was active there for about four or five years. Then, in 1986, the Guardian (not the British newspaper, but the old radical weekly in the United States) announced that they were organizing a tour to see the Nicaraguan election. I went down there with them, and what I saw was incredible.

The major lesson I learned was that Sandinista supporters came from many different directions politically. It was nothing like the SWP: it was a mass revolutionary movement. This confirmed to me what Peter [Camejo] had said. He was trying to build a current in the United States that could adopt the lessons of the Central American revolutions — by putting aside the hammer and sickle, for example, and using the language and the iconography of the United States.

While in Nicaragua, I was riding on a bus, going to different farming cooperatives, seeing the various changes that had taken place there. And a high-school kid, maybe fourteen or fifteen years old, approached me and handed me a leaflet. It said, “Technical Aid to Nicaragua” or “Computer Programmers Needed in Nicaragua,” something like that. I looked at it and thought, Wow.

At the time I was working as a database administrator at Memorial Sloan Kettering in New York City. I had been working on mainframes since 1968. So I started talking to this kid, who told me when I got back to New York I should contact the offices of a group called TecNica in Berkeley.

JW: What was TecNica like back then?

LP: When I first called them up, the guy who answered was Michael Urmann, the founder of the organization. He was an economist. He went to Nicaragua in 1983 or 1984, and he recognized that there had been a huge exodus of people with technical skills from the country.

When I first called them up, the guy who answered was Michael Urmann, the founder of the organization. He was an economist. He went to Nicaragua in 1983 or 1984, and he recognized that there had been a huge exodus of people with technical skills from the country.

When he got back to the United States, he started building a movement to recruit Americans that could help Nicaraguans make use of technology — including technologies they already had from the [prerevolutionary] Somoza era, as well as new developments like microcomputers.

I returned to Nicaragua as part of TecNica less than a year after I got back to New York. I even resigned from my position at Memorial Sloan Kettering with the intention of working in Nicaragua. When I got there, I gave classes in structured systems design to a group of people working in their Federal Reserve [Banco Nacional de Nicaragua], where they had the largest mainframe in the country. And then I went to the Ministry of Construction, where they wanted me to work full-time.

But I discussed it with Michael, and he told me I’d be of greater use if I went back to New York and focused on recruiting other people. So I did that instead, because I had experience as an organizer from my time in the SWP.

JW: How did you recruit people to make the trip to Nicaragua?

LP: I put ads in the Nation magazine and organized meetings at a loft on Mercer Street in Manhattan. Sometimes as many as eighty people would show up. I had a slideshow I would do; I’d give a pitch, and usually five or six people from the meeting would decide to go.

At one point I got so psyched about the project that I went to an IBM PC-users group in a big auditorium, maybe at New York University. There were like three hundred people in the crowd, and after the speaker gave his remarks he opened up the floor for Q&A. Usually at that point people would ask questions like, “What kind of modem would work best with an IBM AT whatever-the-fuck.” But I raised my hand, stood up, and said, “I just got back from Nicaragua, and there’s a tremendous development taking place there. Computers for the first time ever are being used to promote health and education.”

People started laughing at me. But the guy chairing the meeting called me down to the front and I continued speaking. I said, “This is your chance to use your skills to help change the world for the better.” And at least two or three people from that meeting ended up going down to Nicaragua.

By 1990 or so, we ended up sending about eight hundred people to Nicaragua (including the physicist Alan Sokal, who was a DSA [Democratic Socialists of America] member). For a while, delegations of twelve to fifteen people went every month. And every time a delegation would go down, they would bring about five or six personal computers. For a country that was desperately trying not to waste any money or time or human resources, having a PC, even just to do things like run payroll, made a significant difference.

We started off just organizing programmers, but we quickly diversified to include engineers and machinists of different kinds. This developed into our skilled trades subproject, which involved welders, heavy-duty mechanics, people like that. We raised money to buy parts that were desperately needed in Nicaraguan factories. Then we would send skilled delegations down to train the Nicaraguan workers on how to use the equipment, how to install it, how to repair it themselves.

Let me tell you something: We had every political tendency on the Left going down to Nicaragua in those delegations. They never once fought each other. There was a real “roll up your sleeves and get things done” kind of attitude. We had Workers World, Socialist Workers Party, Communist Party, Maoists, DSA, everybody. They all understood that what was happening in Nicaragua was bigger than their own narrow organizational goals.

JW: That’s a pretty unique experience on the Left. How did TecNica fit into the broader Central America solidarity movement in the United States?

LP: TecNica provided a way for people who wanted to provide technical support to the Nicaraguan revolution to do that. But then those volunteers would come back to the United States and begin talking to other people about Nicaragua. So recruitment was only part of my work.

I also worked to make returned TecNICA volunteers part of that broader solidarity movement. I was on the TecNica executive committee, and I was a member of the New York–Nicaragua Solidarity Network steering committee. We would have weekly meetings and plan out joint events and tablings and so forth.

TecNica provided a way for people who wanted to provide technical support to the Nicaraguan revolution to do that. But then those volunteers would come back to the United States and begin talking to other people about Nicaragua. So recruitment was only part of my work.

I also worked to make returned TecNICA volunteers part of that broader solidarity movement. I was on the TecNica executive committee, and I was a member of the New York–Nicaragua Solidarity Network steering committee. We would have weekly meetings and plan out joint events and tablings and so forth.We worked closely with the Nicaragua Medical Aid Committee (NicMAC), which was a coalition of doctors and nurses. We made connections with construction brigades and sister-city projects. We even organized dances to raise money.

There was a lot of collaboration. For example, Ben Linder didn’t go to Nicaragua through TecNICA; he went down on his own. But we raised money to send him the things he needed to complete the small-scale dam, or weir, he was building. And after he was killed, a small group of TecNica volunteers went out to finish the rural electrification project he started there [in El CuĆ”, a small town on the Nicaragua-Honduras border].

To be honest, the Central America solidarity movement was the last real radical movement in the United States, as far as I can tell. Actually, I take that back: we’re seeing a new wave of movements now, like Black Lives Matter and Occupy Wall Street. But in the 1980s, before these newer movements, the solidarity movement stood alone.

JW: Tell me about TecNica’s work outside of Nicaragua.

At a certain point, Michael Urmann and I started meeting with some people at the Cuban embassy to discuss starting a project for Cuba.

Our contact at the embassy was a member of the Cuban intelligence agency who was living out on Long Island. He would call me in the morning to say [imitating Cuban accent], “Luis, meet me. Fifty-sixth street and second avenue. Two o’clock.” He would get in his car and drive away from New York City, then take a sharp turn to come back.

Somehow the FBI found out that we were meeting with him. It all happened in a few days. They [FBI agents] started going to places like Bell Labs, really top-of-the-line companies [that employed computer programmers]. They would go into the personnel office and say, “Are you aware your employees may be working with an espionage network?” They accused TecNica of transferring “high technologies” to the Soviet Union through Cuba.

It became a huge story. Nightline with Ted Koppel even ran a whole thirty-minute episode about the allegations — but the focus of the story was a TecNica volunteer who was just going around repairing electrical pylons that supplied electricity to Managua. The media coverage was such a repudiation of the FBI that they ultimately just dropped their case against us.

Around this time, we also started working in Africa. In the late 1980s I went on a needs assessment trip to the headquarters of the African National Congress (ANC) in exile, where I met with Thabo Mbeki and his wife, Zanele Dlamini Mbeki. It just so happened that she was working on Oliver Tambo’s speech for a major ANC conference at the time. And she couldn’t save it! So I bailed her out and I showed her how to save the file [laughs].

After Nelson Mandela got out of prison [in 1990], we had people working in South Africa, in Angola, in Zimbabwe. We sent somebody over to Namibia to train SWAPO [South West Africa People’s Organisation] how to use desktop publishing to run their propaganda campaigns.

JW: Why did TecNica’s work wind down?

LP: After [anti-Sandinista president] Violeta Chamorro was elected [in 1990], it became a lot harder to raise money. During the 1980s, TecNica had a donor base that included some wealthy people. But after 1990, because Nicaragua sort of disappeared as a galvanizing force, the money dried up.

The only project that continued was the skilled trades subproject, because the people working on it had been around the Communist Party and knew how to get things done. They continued to stay in touch with blue collar workers in Nicaragua, helping them out. But other than that, it just dissipated. It all

JW: How did your experience with TecNica affect the way you think about socialist politics and the international left?

LP: When you’ve seen a place like Nicaragua it’s not hard to understand why these countries are so vulnerable. We’re talking about a country that’s the size of Brooklyn with a GDP that’s equal to what Americans spend on blue jeans each year! This is one of the reasons I really hate people like Reagan and Trump.

I went to work at Columbia University after I left TecNica in 1991. I retired about four or five years ago. What I do now, mostly, is write about the need to unite the Left. I’m trying to share some of the strategic orientation I learned from Camejo, who learned it from the Sandinistas, who learned it from the Cuban revolutionaries, from MariĆ”tegui, and from the Latin American left.

In Latin America, the Left has had to deal with real questions of survival and revolutionary strategy. When you have a class struggle that’s so sharply posed, you can’t think in terms of bullshit sectarian schemas. Because you have people who are being killed! In Nicaragua, under Somoza, they were throwing people out of helicopters.

When I left the SWP, I enrolled in a writers’ workshop at NYU and told myself I was putting politics behind me. Fuck that shit, I thought. But then I would open up the Times in the morning and read about El Salvador and Nicaragua, and the pull was just too strong.I find I always identify with the people who are at the bottom trying to change things. It’s quixotic.

Tuesday, August 17, 2021

3543. The Animal Origin of SARS-CoV-2

  • By Spyros Lytras
  • Wei Xia
  • Joseph Hughes, 
  • Xiaowei Jiang
  • David L. Robertson, Science Magazine, August 17, 2021


  • Although first detected in December 2019, COVID-19 was inferred to be present in Hubei province, China, for about a month before (1). Where did this new human disease come from? To understand the origin of the COVID-19 pandemic, it is necessary to go back to 2002. At that time a novel respiratory coronavirus appeared in Foshan, Guangdong province, China, and spread to 29 countries (2). Altogether ~8000 people were infected with severe acute respiratory syndrome coronavirus (SARS-CoV) before public health measures controlled its spread in 2003. The zoonotic origin of SARS-CoV was subsequently linked to live animals available at markets. Further sporadic spillover events of SARS-CoV from animals took place in Guangzhou, Guangdong, and some researchers working with cultured virus were infected in laboratory accidents (3), but ultimately SARS-CoV was removed from the human population. Trading of susceptible host animals is an important common theme in the origins of SARS and COVID-19.

    Three years after the SARS epidemic began, investigations revealed that horseshoe bats (Rhinolophus) in China were harboring related coronaviruses (4). These collectively form the species SARS-related coronavirus (SARSr-CoV), which comprises the Sarbecovirus subgenus of the Betacoronavirus genus. It was inferred that a sarbecovirus circulating in horseshoe bats seeded the progenitor of SARS-CoV in an intermediate animal host, most probably civet cats (3). Although other possible intermediate hosts for SARS-CoV were identified, in particular raccoon dogs and badgers (for sale with civet cats in animal markets), it is a population of civet cats within markets that appear to have acted as the conduits of transmission to humans from the horseshoe bat reservoir of SARS-CoV, rather than civet cats being a long-term reservoir host species. Presumably a captive civet cat initially became infected by direct contact with bats—e.g., as a result of bats foraging in farms or markets—or was infected prior to capture. Following the SARS epidemic, further surveillance revealed the immediate threat posed by sarbecoviruses from horseshoe bats. Despite this clear warning, another member of the SARSr-CoV species, SARS-CoV-2, emerged in 2019 that spread with unprecedented efficiency among humans. There has been speculation that the Wuhan Institute of Virology (WIV) in Hubei was the source of the pandemic because no SARS-CoV-2 intermediate host has been identified to date and owing to the WIV’s geographic location.

    SARS-CoV-2 first emerged in Wuhan city, which is >1500 km from the closest known naturally occurring sarbecovirus collected from horseshoe bats in Yunnan province, leading to an apparent puzzle: How did SARS-CoV-2 arrive in Wuhan? Since its emergence, sampling has revealed that coronaviruses genetically close to SARS-CoV-2 are circulating in horseshoe bats, which are dispersed widely from East to West China, and in Southeast Asia and Japan (5). The wide geographic ranges of the potential reservoir hosts—for example, intermediate (R. affinis) or least (R. pusillus) horseshoe bat species, which are known to be infected with sarbecoviruses—indicate that the singular focus on Yunnan is misplaced (5). Confirming this assertion, the evolutionarily closest bat sarbecoviruses are estimated to share a common ancestor with SARS-CoV-2 at least 40 years ago (5), showing that these Yunnan-collected viruses are highly divergent from the SARS-CoV-2 progenitor. The first of these viruses reported by WIV, RaTG13 (6), is certainly too divergent to be the SARS-CoV-2 progenitor, providing key genetic evidence that weakens the “lab-leak” notion. Additionally, three other sarbecoviruses collected in Yunnan independently of WIV are now the closest bat coronaviruses to SARS-CoV-2 that have been identified: RmYN02, RpYN06, and PrC31 (see the figure).

    So, how did SARS-CoV-2 get into humans? Although it is possible that a virus spillover occurred through direct horseshoe bat–to–human contact, a known risk for SARSr-CoVs (7), the first detected SARS-CoV-2 cases in December 2019 are associated with Wuhan wet markets (8). This is consistent with multiple animal-market–associated spillover events in November and December (9). It is currently not possible to be certain of the animal source of SARS-CoV-2, but it is notable that live animals, including civet cats, foxes, minks, and raccoon dogs, all susceptible to sarbecoviruses, were for sale in Wuhan markets, including the Huanan market (identified as an epicenter of the outbreak in Wuhan) throughout 2019 (10). Many of these animals are farmed for their fur at large scale and then sold to animal markets (11). Some of these farmed species (American minks, red foxes, and raccoon dogs) were sold alive for food by Wuhan animal sellers, as was trapped wildlife (including raccoon dogs and badgers), although no bat species were for sale (10). Together, this suggests a central role for SARSr-CoV–susceptible live intermediate host animals as the primary source of the SARS-CoV-2 progenitor that humans were exposed to, as was the case with the origin of SARS.

    If these routes of transmission to humans are in place, why is emergence so rare that only two major outbreaks have occurred in the last two decades? Spillover events are not so unusual in locations where more frequent human-animal contacts take place. This is indicated by serology studies showing evidence for SARSr-CoV–specific antibodies in people living in rural locations (12), and even higher rates recorded in people living near bat caves (7). Spillover risk will increase with human encroachment into rural areas, resulting from new travel networks around and between urban areas. When a novel virus is then exposed to a densely packed human population, such as in Wuhan city, these spillover events have a much higher chance of resulting in substantial onward spread (1).

    One particular ecological event in China that severely disrupted meat trade, and thereby contributed to increased wildlife–human contacts, was the shortage of pork products in 2019. This was a direct consequence of the African swine fever virus (ASFV) pandemic (11), which led to ~150 million pigs being culled in China, resulting in a pork supply reduction of ~11.5 million metric tons in 2019. Although production of other meat, such as poultry, beef, and fish products, moderately increased and China imported more of these products from international markets to mitigate the shortfall, this supply only covered a fraction of the ASFV-associated pork losses. Consequently, pork prices hit a record high in November 2019, with the wholesale price increasing ~2.3 times compared with the previous year. Moreover, pig production has been relocating from Southern to Northern China since 2016. This, coupled with tight restrictions on the movement of live pigs and pork products to mitigate the ASFV pandemic, reduced the availability of pork in the Eastern and Southern provinces, resulting in much steeper price increases in these regions. In response, food consumers and producers may have resorted to alternative meats, including farmed or captured wildlife, especially in Southern China where wildlife is traditionally consumed (11). The resulting increased trade of susceptible farmed animals and wildlife could have brought humans into more frequent contact with meat products and animals infected with zoonotic pathogens, including SARSr-CoVs.

    There are controversial reports of human SARS-CoV-2 cases in China being traced back to contact with imported frozen foods and SARS-CoV-2 apparently identified from frozen food, packaging, and storage surfaces (13). In an effort to prevent ASFV spread through live pig transportation routes, supply through the cold chain has been encouraged by the Chinese government since October 2018, with stronger support since September 2019 in the form of waiving freeway toll fees for frozen pork. The large demand for pork meat facilitated the use of cold-chain transport for all meat types, in particular from places with lower prices to those with higher prices, legally (or illegally), potentially also including transport of species susceptible to SARSr-CoV infection. The World Health Organization (WHO) Origins Report (8) recorded carcasses of wildlife, particularly badgers, left behind in freezers at the Huanan market, as well as their sale as frozen goods in late December 2019. It is likely that this wildlife had been trapped or farmed elsewhere and sold to Wuhan markets through the cold chain. Exposures could also potentially occur through feeding of coronavirus-infected carcasses to live animals either in transport or at markets.

    The emergence of SARS-CoV-2 has properties that are consistent with a natural spillover (9). Although carriage from a bat cave of a sarbecovirus close enough to SARS-CoV-2 to be the progenitor as a research sample to the WIV is theoretically possible, such a scenario would be extremely unlikely relative to the scale of human-susceptible animal contacts routinely taking place in animal trading. Alternatively, bat guano (feces) is collected for use as fertilizer, again on a much larger scale than irregular research visits to bat caves, consistent with rare but ongoing SARSr-CoV transmissions to humans in rural areas (712).

    Overall, SARSr-CoV animal-to-human transmission associated with infected live animals is the most likely cause of the COVID-19 pandemic. However, the massive scale of cold-chain supply, particularly following disruption to the meat industry in China caused by ASFV-associated culling, suggests that frozen susceptible-animal carcasses, either for human or animal consumption, should not be discounted as playing a role in the emergence of SARS-CoV-2. This will especially be the case if the progenitor population of SARS-CoV-2 is found further away from Wuhan, because live-animal trafficking is much more likely to involve more proximal locations to the city, e.g., the prefectures of Hubei province. Serology, sampling and interviewing of the individuals (e.g., trappers, traders, and farmers) connected to the sources of wildlife sold in the Wuhan markets in October and November 2019 would be a sensible next step in future investigations.

    Once in the human population, SARS-CoV-2 has spread surprisingly rapidly for a new human pathogen. Contrary to classical expectations for a host species jump, SARS-CoV-2 is highly capable of human transmission, including frequent asymptomatic transmission and amplification through superspreader events. This initial ”success,” at least prior to the emergence of variants of concern, is unlikely to be due to early adaptation to humans but rather can be attributed to the relatively generalist nature of SARS-CoV-2 (14), evidenced by frequent transmission to mammals: minks, cats, and others. Worryingly, recent experimental evidence has found that the pangolin-derived sarbecoviruses (presumably acquired from exposure to horseshoe bats or other infected animals after illegal trafficking into China) can also infect human cells and have spike proteins that are even better at facilitating entry into human cells than that of SARS-CoV-2 (15). Collectively this points to a further risk of spillover that extends to the more divergent members of the lineage that SARS-CoV-2 emerged from and implies frequent spillovers from bats to other susceptible wildlife.

    Humans are now the dominant SARS-CoV-2 host species. The danger is that SARS-CoV-2 could spread from humans to other animal species, termed reverse zoonosis, as is suspected for white-tailed deer in the United States. The promiscuous infection of various host species by the sarbecoviruses means that future spillovers of SARSr-CoVs from wildlife are very likely, and current vaccines may not be protective against novel variants. The sampling intensity of sarbecoviruses needs to be urgently increased to gain a better understanding of this spillover risk. The recent finding of sarbecoviruses, not dissimilar to SARS-CoV-2, dispersed in Southeast Asia emphasizes the urgency of monitoring coronavirus diversity. Humanity must work together beyond country borders to amplify surveillance for coronaviruses at the human–animal interface to minimize the threat of both established and evolving variants evading vaccines and to stop future spillover events.


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    References and Notes

    ACKNOWLEDGMENTS: We thank the researchers who have shared genome data openly via GenBank or GISAID. D.L.R. and J.H. are funded by the Medical Research Council (MRC) (MC_UU_1201412) and D.L.R. by the Wellcome Trust (220977/Z/20/Z). S.L. is funded by an MRC studentship.