An alien zoologist on an expedition to collect samples of intelligent life on Earth would probably take a few of us back for further observation. But what other species on Earth would also be on the alien’s specimen shelves? Our extraterrestrial Attenborough’s choice would probably very much surprise us: while many of us would like to think there is a huge and unbridgeable chasm between human intellect and the ways the minds of other animals work, in every aspect so far investigated the difference is one of degree rather than of kind.

There would likely be elephants. These large mammals seem to take genuine pleasure in creating images (painting with their trunks), mourn their dead, show empathy, deliberately deceive each other and have complex political structures. If the aliens opted to take away other tool users, it would mean not