For @NYTmag I wrote about the possible origins of the new coronavirus, the profound links between ecological disturbance and disease outbreaks, and why zoonoses do not so much leap as flow https://www.nytimes.com/2020/06/17/magazine/animal-disease-covid.html

We don't yet know exactly how the pandemic began, but current evidence indicates that, as with SARS-1, the likely source of SARS-CoV-2 is horseshoe bats. How, then, did the virus travel from a bat's body to one of China's most populous cities? There are many possibilities:

Bats may routinely infect people, wildlife, & livestock in rural areas of China; those people & animals may then travel to larger urban areas. Someone hunting bats or collecting guano may have started a chain of infection. Bats or other vectors may have been smuggled into China.

The fact that most of the early cases had some link to the Wuhan seafood market does not mean the outbreak began w/ bats sold there. It's entirely possible the market was instead an amplifier: that someone(s) arrived at the market already infected and further spread the virus.

One could imagine thousands of possible trajectories & permutations, but if bats are the source of SARS-2, then some pathway involving the farming/hunting/trading of wildlife/livestock—& possible hybridization of a bat virus w/ another creature's virus (pangolin?)—is probable.

Asia is not the only place where people hunt, breed, and eat wildlife. These are global practices.

And they are just some of the many ways that humans disrupt ecosystems and ultimately make zoonotic outbreaks much more likely. Our impact on global ecosystems is staggering.

Consider Nipah, the disease that inspired the film Contagion: intensive farming/logging + fires in Malaysia > destroyed bat habitat > bats forage on cultivated fruit trees overhanging pigsties (below) > pigs eat fallen pieces of bat-nibbled fruit, contract virus, pass to humans

Or Lyme: human encroachment fragments forest > predators/large mammals/specialized species decline; generalist species like mice proliferate > white-footed mice are excellent hosts for ticks/bacteria that cause Lyme > more mice = increased risk of Lyme for people nearby

Similarly, in areas w/ high bird diversity, West Nile virus pings between unsuitable hosts & has difficulty establishing itself. In urban environments w/ low bird diversity, where generalist species/suitable hosts like American robins thrive, the risk of infection is much greater

One example of the sometimes circuitous links between human society, ecosystem disruption, and public health really stuck with me. An outbreak of West Nile in CA was partly due to...the housing crisis! Abandoned swimming pools became ideal breeding grounds for mosquitoes.

In sum: "As we restructure Earth’s biosphere to suit our whims, we open hidden conduits between other animals’ microbiomes and our own...Other animals’ diseases have not so much leapt onto us as flowed into us through channels we supplied."