Welcome to What’s Up Docs?, the podcast where doctors and identical twins Chris and Xand van Tulleken explore every aspect of our health and wellbeing.

In this special episode, recorded before a live audience at the Hay Literary Festival in Wales, Chris and Xand discuss the anatomy of the smile, its evolutionary origins and some of the health claims about smiling. Is smiling uniquely human? Can the simple act of moving our muscles to form a smile make you feel happier? And is smiling the same across cultures and genders? To find out, they’re joined by several experts and an African street dog named Jack.

Featuring Professor Ben Garrod from the University of East Anglia, Dr Magdalegna Rychlowska from Queen’s University, Belfast and Sinead Rushe from the Royal Academy of Dramatic Arts in London.

If you want to get in touch, you can email us at whatsupdocs@bbc.co.uk or WhatsApp us on 08000 665 123.

Presenters: Drs Chris and Xand van Tulleken Guest: Professor Ben Garrod Producer: Rami Tzabar Executive Producer: Jo Rowntree Editor: Kirsten Lass Assistant Producers: Maia Miller-Lewis and Grace Revil Tech Lead: Reuben Huxtable Social Media: Leon Gower Digital Lead: Richard Berry Composer: Phoebe McFarlane Sound Design: Melvin Rickarby

At the BBC: Assistant Commissioner: Greg Smith Commissioning Editor: Rhian Roberts

A Loftus Media production for BBC Radio 4