Chameleons don’t change colour to match the background. They change colour as a result of different emotional states. Chameleons change colour when they beat another chameleon in a fight. They change colour when a member of the opposite sex steps into view and they sometimes change colour due to fluctuations in either light or temperature.

A chameleon’s skin contains several layers of specialised cells. Altering the balance between these layers causes the skin to reflect different kinds of light, making chameleons a kind of walking colour-wheel. It’s odd how persistent the belief that they change colour to match the background is. The myth first appears in the work of a minor Greek writer of entertaining stories and potted biographies. Aristotle, far more influential and writing a century earlier, had already, quite correctly, linked the colour-change to fear. But it’s come back with a vengeance since and to this day is perhaps the only thing most people think they ‘know’ about chameleons.