We often associate yawning with being tired or bored - but this week's episode explores whether it could be a clever way to cool down our brains?
Hannah and Dara discover humans aren't the only species that yawn. From cats to chimpanzees and even fish, plenty of other vertebrates engage in this ancient behaviour which scientists believe evolved hundreds of millions of years ago. And it doesn't always happen as a spontaneous reflex to feeling tired but can also be triggered by watching other people do it.
If you have an everyday mystery for the team to investigate, contact them on curiouscases@bbc.co.uk
Contributors:
Stephen Jackson - Professor of Cognitive Neuroscience, University of Nottingham Laura Kelley - Associate Professor in Behavioural Ecology at University of Exeter
Dr Andrew Gallup - Professor of Behavioral Biology at Johns Hopkins University
Producer: Lucy Taylor Executive Producer: Sasha Feachem A BBC Studios Production