What happens if you cross a fish that has white spots on a black body with another fish that has black spots on a white body? You might think that you’d get a fish with a single uniform colour, or one with both types of spots. But the hybrid’s skins are very different and far more beautiful. It does not inherit its parents’ palettes, overlaid on top of each other; instead, it gets a mesmeric swirl of black and white that looks like a maze on its skin.
To understand where these hybrid patterns come from, you need to look at how fish decorate their skins in the first place. These patterns can be very complicated, as even the briefest swim through a coral reef will tell you, but they also vary from individual to individual – one trout will have a slightly different array of spots to another. These differences tell us that intricate patterns aren’t stamped onto a fish’s skin according to a genetically encoded blueprint. They’re living patterns, generated through a lively dance between a handful of molecules.