In the early 20th century, the world was captivated by a mathematical horse called Clever Hans. He could apparently perform basic arithmetic, keep track of a calendar and tell the time. When his owner, Wilhelm von Osten, asked him a question, Hans would answer by tapping out the correct number with his hoof.

Eventually, it was the psychologist Oskar Pfungst who debunked Hans’ extraordinary abilities. He showed that the horse was actually responding to the expectations of its human interrogators, reading subtle aspects of their posture and expressions to work out when it had tapped enough. The legend of Hans’ intellect was consigned to history. But history, as we know, has a habit of repeating itself.

For the last few decades,