Ella Al-Shamahi asks why do we laugh?Some people might not have a sense of humour, you might even know someone who never laughs… but there isn’t a culture out there, say a tribe, where people just never laugh. It does appear to be universal but how universal and how primal? Many mammals and the great apes ( chimpanzees, gorillas and bononbos) laugh. Orangutans diverged from the other great apes including us about 12 million years ago and because we all laugh that suggests our shared common ancestor laughed. So what is the purpose of laughing? Ella talks to Professor Sophie Scott from University College London and stand-up comic Ria Lina.