Prof Richard Klein believes art is a landmark in human evolution. Unquestionable art that’s widespread and common suggests you’re dealing with people just like us. No other animals, after all, are able to define a painting as anything other than a collection of colours and shapes. This ability is unique to humans.

Other scientists agree. They believe art defines humans as behaviourally modern, and its beginning must coincide with the ability to speak and use language. If someone has the imagination to devise a shared way to describe their environment using art then it seems inconceivable that they could not possess language and speech. The search for the moment our ancestors became behaviourally just like us is also the hunt for the first evidence of art.