#*?@! %$&@*! Why do a few, select words have such power to shock and offend? With help from swearing historian Melissa Mohr, Mike Williams traces the history of taboo language from Roman times to the present day and hears how cultural taboos have shaped offensive language down the centuries. He talks to American psychologist Professor Tim Jay about why we swear and discovers that children start using profane language at a much earlier age than you might imagine. And he meets psychologist Dr Richard Stephens who persuades him to take part in two swearing experiments, one of them rather painful, with some surprising results.(Picture: A teenage boy in a hoodie making an offensive gesture, censored. Credit: BBC)