You read a book, laugh a lot, recommend it to your friends. Some laugh, others don’t. Why is a sense of humour so individual and at the same time so culturally specific? We are mostly moved to the same emotional responses by tragedy, but we don’t laugh at the same things and I’ve always wondered why. There are many kinds of humour and life would be intolerable without it, but as society changes, so humour changes too. We still weep at old Greek tragedies – but laugh at old Greek comedies? Not so much.