Wild grasses, like wheat, rice and barley, have long stalks that shatter to spread their seeds over the surrounding soil. But this doesn’t always work. A small number of genetic changes (mutations) can lead to shatter-proof stalks, whose seeds stay in place. These mutations are bad for the plant, but they’re spectacularly convenient for humans because they concentrate seeds in one easy-to-harvest place.

When our ancestors collected these mutant grains, they spilled some on the way back to camp, or excreted the seeds on their latrines. They might even have planted some deliberately. Either way, those shatterproof mutations—typically, one per crop—became some of the most critical in human history. They allowed us to domesticate the plants that fuelled the