Several years ago, Michael Pollan had a disturbing encounter. The relentlessly curious journalist and author was at a conference on plant behaviour in Vancouver. There, he’d learned that when plants are damaged, they produce an anaesthetising chemical, ethylene. Was this a form of self-soothing, like the release of endorphins after an injury in humans? He asked František Baluška, a cell biologist, if it meant that plants might feel pain. Baluška paused, before answering: “Yes, they should feel pain. If you don’t feel pain, you ignore danger and you don’t survive.”