It Probably Came From Bats
Tracing the evolutionary lineage of the coronavirus
One of the most enduring mysteries of the coronavirus is where it originated. It was first traced to a wet market in Wuhan — where vendors sell produce, meat, seafood, and occasionally live animals — which raised the likely possibility that it came from an animal. But which one? Much of the research pointed to bats (which are common reservoirs for viruses), but other work implicated pangolins, a cute species of anteaters that’s highly prized for its scales. Research published in Nature in March made very clear that it was not designed in a lab, despite the conspiracies entertained by the White House.
Research published in Nature Microbiology on Monday shed more light on the true animal origin of the coronavirus. The researchers, led by Maciej Boni, PhD, of the Center for Infectious Disease Dynamics at Pennsylvania State University, reconstructed the evolution of SARS-CoV-2 by looking closely at its genome as well as that of closely related viruses. They wanted to know where on the virus evolutionary tree SARS-CoV-2 branched off. Whatever virus it stemmed from would tell them what animal it originated in.
The succinct summary of the paper by MIT Technology Review reporter Neel Patel on Twitter is hard to top: “It’s bats, you guys. It came from bats.”
It wasn’t easy to trace the origins of SARS-CoV-2 because coronaviruses tend to trade genetic material with one another. The patchworked genome that results from this process, known as recombination, is hard to place on an evolutionary tree because its ancestry isn’t linear. To work around this, the researchers had to identify parts of SARS-CoV-2’s genome that definitely did not exchange genetic material in this way. These parts would be easier to compare to known related viruses, like the bat virus RaTG13 and the pangolin virus known as Pangolin-2019.
Their analyses revealed that SARS-CoV shares a recent ancestral lineage with the bat virus RaTG13. This means they came from the same branch of the evolutionary tree, but SARS-CoV-2 eventually peeled further away through other evolutionary events that occurred 40 to 70 years ago.
Further evidence for a bat origin comes from their analysis of SARS-CoV-2’s much-discussed…