We still don’t know exactly how SARS-CoV-2 made the jump to humans. But we do know that wildlife trading makes the virus (and many others like it) much more likely to jump from animals to humans.

The first suspect was bats: bats are notorious for having very strong immune systems that encourage the development of strong viruses — as researchers like to put it, bats are a reservoir for viruses. This initial supposition led to the closure of a food market in Wuhan, China, where animals (including live and wild animals) were sold alongside other food items.

But there are key differences from bat coronaviruses and SARS-CoV-2, suggesting that an intermediary host may have been involved.

Previous studies have found striking similarities to viruses found in pangolin. A new study adds more evidence to that theory and offers a strong reason to ban wildlife trading: it’s only a matter of time before another virus makes the jump this way.

A team led by Yan-Ling Hu of Guangxi Medical University and Yi Guan of the University of Hong Kong analyzed viruses collected from a small number of pangolins seized in antis-muggling raids in 2017 and 2018. The researchers isolated the viruses and analyzed them, finding spike proteins that strongly resemble those of SARS-CoV-2. It’s still not certain that this means the virus jumped from pangolins to humans, but it makes a strong circumstantial case for it.

The reason why this is so important is that these spike proteins are exactly what was different between bat coronaviruses and SARS-CoV-2. There’s no smoking gun yet, but more and more, it seems like the virus passed through pangolins on its way to humans.

But here’s the thing: even if it didn’t, even if it came through another animal pathway, there’s a good likelihood that other viruses will jump from pangolins to humans.

“The discovery of multiple lineages of pangolin coronavirus and their similarity to SARS-CoV-2 suggests that pangolins should be considered as possible hosts in the emergence of novel coronaviruses and should be removed from wet markets to prevent zoonotic transmission,” the study concludes.

Pangolins are often considered the world’s most trafficked animals, and they have been brought to the brink of extinction by illegal trafficking, primarily for its scales which are used in traditional Chinese medicine.

If we needed a stronger reason to ban all this traffic (and enforce it properly), here it is: if we don’t do it, we may have to deal with another pandemic soon enough.

The study has been published in Nature.