Maria Cardona: Why would it be most emotions that we experience that are intrinsically rewarding have some evolutionary purpose? She says when we play, we learn. And I'd actually love to hear from our listeners about what they do for fun and what some of those fun experiences are for you. So if you're from a recording, record your name and send it to nscuetfreak@aol.com. You can also email us at jennifer.cardona@mailonline.co.uk.