London Zoo’s gorilla likes to eat his bogies. I once spent an hour watching him. He sat on a plinth with his face pressed up against the glass. He picked and he picked and he picked. It was grotesque. It was beautiful. It was impossible to turn away as he burrowed and fossicked and savoured his spoils. At first I thought he was doing it out of boredom. Then I realised he was doing it to shock. When the kids squealed with laughter and their mothers shrieked in horror, there was a glint in his eye.