Animal magic: why intelligence isn’t just for humans

Meet the footballing bees, optimistic pigs and alien-like octopuses that are shaking up how we think about minds

How do you spot an optimistic pig? This isn't the setup for a punchline; the question is genuine, and in the answer lies much that is revealing about our attitudes to other minds - to minds, that is, that are not human. If the notion of an optimistic (or for that matter a pessimistic) pig sounds vaguely comical, it is because we scarcely know how to think about other minds except in relation to our own.

Here is how you spot an optimistic pig: you train the pig to associate a particular sound - a note played on a glockenspiel, say - with a treat, such as an apple. When the note sounds, an apple falls through a hatch so the pig can eat it. But another sound - a dog-clicker, say - signals nothing so nice. If the pig approaches the hatch on hearing the clicker, all it gets is a plastic bag rustled in its face.