More than a year into the COVID-19 pandemic, scientists still aren’t sure where exactly the virus that caused this mess came from, and how it was able to spread so rapidly among humans. With the origins of the coronavirus still up in the air, there’s been a lot of talk of the so-called lab leak theory—the idea that the virus spread to people in a laboratory accident, rather than jumping from a wild animal to a human. Advertisement In recent days, there’s been a flurry of speculation, and it can be hard to parse what the lab leak theory is all about, how likely it is, and why it matters at all. Here’s our attempt to sort some of that out.