It is a disquieting thought that our heads contain a neurological version of a peacock's tail - an ornament designed for sexual display, whose virtuosity at everything from calculus to sculpture is perhaps just a side-effect of the ability to charm. I end with one of the strangest consequences of sex -that the choosiness of human beings in picking their mates has driven the human mind into a history of frenzied expression for no reason except that wit, virtuosity, inventiveness and individuality turn other people on.
-- Matt Ridley