Scientists have discovered new genetic evidence in a market in Wuhan, China, where COVID cases first amassed in late 2019. The findings support the existence of an animal origin of SARS-CoV-2, the virus that causes COVID. They were presented to an advisory group convened by the World Health Organization earlier this week.

Florence Debarre is an evolutionary biologist at the French National Center for Scientific Research. genetic sequences discovered virus that researchers in China led by George Gao, former head of the Chinese Center for Disease Control and Prevention, uploaded to a public genomic database called GISAID. Subsequently, the sequences were filmed but not uploaded or analyzed by several other researchers from different countries. Samples containing viral RNA collected at the Huanan Seafood Wholesale Market in early 2020 also contained genetic material from raccoon dogs — a fox-like canine that appears to be sold at the market — as well as other animals. The genetic material came from the same market areas where SARS-CoV-2 was found, suggesting that raccoon dogs may have been infected with the virus (possibly by other animals) and may have been the first to transmit the virus to humans. .

The virus caused a global pandemic that killed nearly seven million peopleand controversy erupted as to whether this was due to natural spread from wildlife to humans or lab leak from a coronavirus research facility in Wuhan. The new data does not directly prove that SARS-CoV-2 entered the human body from infected raccoon dogs, but it adds to the growing body of evidence in favor of spread from animals.

“These data do not definitively answer the question of how the pandemic began, but every nugget of data is important in getting us closer to that answer,” said World Health Organization Director-General Tedros Adhanom Ghebreyesus. at the briefing on Friday. The scientists who are analyzing the data are currently preparing a report on their findings, which they hope to publish in the coming days.

Scientific American talked to one of the researchers who analyzed the samples: Joel Wertheim, an evolutionary biologist at the University of California, San Diego. He described the new discovery and explained what it adds to our understanding of the origin of COVID.

[An edited transcript of the interview follows.]

What do the new results show and how do they fit into the broader context of the search for the origin of COVID?

First, I’ve been waiting to see these sequences for over a year, maybe two. And we have long thought that they will confirm the presence of susceptible hosts and the virus in the same place and at the same time in the market.

So you knew that these samples existed, but they were not publicly available?

Yes, it seems that [the Chinese researchers have] made several sequencing runs on the samples. So I don’t know when they were made… We know that the Chinese [scientists] had older designs based on [a] preprint from 2022. And we knew these samples existed because of a leaked document in early 2020. [Editor’s note: This preprint is currently under review for possible publication.]

But that previous preprint didn’t mention animal sequences, right?

Yes, it didn’t specifically mention where the non-viral genetic material came from, other than samples taken from humans. I had long suspected that at least one of these points on their chart was from raccoon dogs. And so it is.

How strong is the evidence for the natural spread of SARS-CoV-2 at present?

Well, first off, I’d like to just say that even before this data was published, the overwhelming amount of scientific evidence was pointing to the natural distribution of zoonoses. [an animal disease jumping into humans] for quite some time. These new data are fully consistent with this scenario. Now the important thing is that I think it would be a mischaracterization to say that these sequences show that raccoon dogs or any other mammalian host species were infected with these viruses because all we are showing is the co-emergence of genetic material from host environment. It’s not the same as smearing a raccoon dog. And it’s not the same as watching a raccoon dog transmit a virus to a human, which of course we never see. We will never get evidence of this level. But first and foremost, it is forensic evidence that these alleged host animals were present on the market. There are no more questions about this. And they were in the same place as the virus.

It is now clear that some of these environmental samples contain the virus due to infected people. But it stretches the imagination to say that only humans spread this virus wherever hosts were susceptible, and that only humans transmitted it to animals. Given everything else we know about the early days of COVID and everything we know about zoonotic viruses, this fits. Will this put an end to the lab leak plot? No. Nothing will ever do it. But I think it should help convince more intelligent scientists.

Can you point out if there is any evidence at all for the lab leak hypothesis – at least the “bona fide” version, treating such a leak as some sort of accident?

The problem with the conscientious version of the lab leak hypothesis is that it doesn’t exist. There is a scientist who becomes infected in the field, a scientist who becomes infected in the laboratory with a virus that has yet to be described, a serial passage or an increase in the function of a weapon – I mean that each of these laboratory leak hypotheses are mutually incompatible with each other.

Looking at the viral genome, we see nothing suspicious about [some] a kind of laboratory manipulation; we really don’t. The most merciful explanation that still remains is that you have some lab worker who gets infected with a virus that the lab hasn’t yet characterized, brings it to the Huanan market and places it there potentially a few times, and then animals, who are sold there become infected. And none of these laboratory assistants transmits [the virus] anyone who can help epidemiologists track it down without them becoming seroreactive [having antibodies to the virus indicative of previous infection] when checking later.

You say the chain of events seems unlikely. What do you think of the recent Department of Energy report that concluded “with low confidence” that the most likely source was a lab leak?

I have no idea what was in the Department of Energy report. I cannot comment in detail on a report that has not been described or that I have never seen. But I can’t imagine what real evidence they have. Especially now, in the light [the new animal evidence].

These early cases [were] tied to the market. Yes, there was a lot of confusion. But once we discarded all assumptions and data that did not stand up to scrutiny, only the market remained. And everything we’ve done since then, from geographic analysis to genomic analysis, and now forensic genetic analysis, all point to natural zoonosis in the marketplace.

Regardless of the true origin of SARS-CoV-2, should we still be concerned about lab security to prevent potential leaks of deadly pathogens?

Certainly. I don’t know a single virologist who doesn’t take biosecurity seriously. But when it comes to research to improve the functionality and safety of laboratories, this discussion should be separated from the discussion of COVID, because these are two different issues. The circumstances of origin are unrelated and it would be a mistake to confuse them.

Returning to the new genetic data, what information do you still hope to extract from it in the coming weeks?

There is genetic material from [market] stalls that did not have SARS-CoV-2. I would be very interested to see them. There is still genetic data from the market that hasn’t been available… I think previous sequencing runs may still be out there and I think it’s necessary to share this data with the whole group so that scientists from all stripes can come in and [study them].

Will you and your colleagues publish these findings?

We are about to publish a report summarizing our findings. I would say [the time frame will be] closer to days, maybe hours.

What is Tulum known for? Well, anyone who has ever heard of this place knows what it is. resorta fancier alternative to Cancun (80 miles north), and over the past few decades an increasingly popular (and crowded) destination for foodies, influencers and tourists in general.

But the ancient Maya lived in Tulum long before it got cold. Actually, skeletal remains found in nearby cenotes and underwater cave systems indicate that the area was inhabited by indigenous peoples 10,000 or more years ago.

Read more: Hard life and mysterious death

Where is Tulum located?

More recently, about 1500 years ago, it was here, on the Caribbean coast of the Mexican Yucatan Peninsula, that the Maya built a city unlike any other. They named him Zama, which means sunrise or dawn – suitable for a city facing east across a sparkling sea. Is located in protected area just a few miles from the modern city center, the archaeological site at Tulum, once neglected and abandoned, has now become one of the premier Maya sites in Mexico. Here’s what we know about ancient Tulum.

Although there may be larger Mayan settlements or places with more impressive structures – Chichen Itzafor example, or nearby koba – Nevertheless, Tulum was an important city and was considered the last major settlement built by the Maya.

Its location was chosen not only to enjoy the sunrise or the Caribbean breeze. Tulum was a port, the only known city built by the Maya on the coast. Historians and archaeologists note that Tulum was a significant trade center on land and sea, dealing with valuable resources such as turquoise and jade obsidianas well as textiles, ceramics and other goods.

Ancient Tulum was built as a fortress

For its size and location, Tulum was extremely well fortified. It is estimated that the construction of the city began sometime in the 6th century AD, during the so-called classical period for Maya. Even today, it is obvious to the most casual visitor that the careful and strategic construction of Tulum took a long time.

While one side faced the sea and was therefore protected by steep cliffs, the rest of the city was bounded by stone walls that were particularly thick—up to 26 feet—and in some places reached 16 feet high. If you traded in luxury goods, it made sense to protect them, but many archaeologists have concluded that the walls were not so much a preventive measure against theft and raids as a barrier between social classes. Apparently, only the ruling and religious elite lived within the city walls, while the commoners lived outside.

Tulum was abandoned by the 16th century

Tulum reached its peak around the 13th and 14th centuries. Visitors at that time would see busy city with buildings painted in vibrant shades of red, blue and green. One of the most attractive site structures, fresco temple, still contains evidence of carved deities and frescoes depicting scenes from Maya culture and mythology. If social media influencers existed at the time, they would have had a day where they took selfies.

The port city continued to prosper for another century or two. Then, in 1518a completely different influential person arrived in the Yucatan: conquistadors. And they weren’t tourists – they were here to stay.

Read more: Why did the Maya leave their once bustling cities?

In a short time, disease, conflict, and other devastations of colonization helped destroy the Mayan civilization as we (and they) knew it. The thick walls of Tulum ultimately offered little in the way of defence; the fortified port became a ghost town by the end of the 16th century.

Ruins of Tulum: how they were discovered

In the mid-19th century, English explorer Frederick Catherwood and American diplomat John Lloyd Stevens traveled the Yucatan, writing an influential book that introduced much of the Western world to Maya culture. In 1841, they first saw the ruins of ancient Zama. Impressed by the thick barriers surrounding the settlement, they named the place Tulum, which means wall or hedge in the Mayan language.

Yet the ancient city remained off the beaten track for the next 150 years. However, the rise of Cancun in the 1970s and the general development of what would become known as Riviera Maya region for the next 20 years, almost guaranteeing that Tulum will once again regain prominence in the region.

What is Tulum known for?

In the middle of the 20th century, the permanent population of Tulum was estimated at several hundred people. At the turn of the millennium, the population had risen to over 12,000 people, a figure that had almost quadrupled in the last 20 years. But that’s still a tiny number compared to the more than 2 million visitors a year that visit the area today.

Archaeological site of Tulum

Although many of these tourists may limit themselves to the resort area, the ruins of Tulum are still one of the most popular archaeological sites in Mexico. Fortunately, the government has taken some steps to keep the ruins from being eaten to death by many modern “explorers”. Where once visitors could scramble between, over and even inside some of the still-standing ruins, access to the most vulnerable areas is limited today.

But this ancient port city still deserves a visit, whether to admire the architecture and art of a bygone civilization, or to enjoy the sunrise and the Caribbean breeze of a unique settlement whose charm and mystery have once again made it a crossroads. trade.

Read more: How the ancient Maya practiced sustainable agriculture