Animals, as I explained in my recent column for Discover, take precautions not to get sick (including the famous anal cannon). We take precautions too–conscious ones, based on what we have learned about how diseases spread, and perhaps also unconscious ones that lower our risk of infection.

But if those precautions fail, we humans sometimes take medicines to kill off the pathogens making us sick. And there’s an intriguing body of evidence suggesting that animals take medicine too.

A lot of that evidence comes from studies on chimpanzees, our closest living relatives. When they get infected, they will sometimes devour leaves and other vegetation they otherwise never touch. In the case of one plant, the chimps have to first