Curious CrowdScience listeners have suddenly been struck by the oddity of their behaviours. Elise ponders why she blushes. Thankfully, listener David is a vascular surgeon and knows a thing or two about blushing, as he performs operations on people debilitated by constant red-dening. He has some answers for us, but asks why did blushing evolve? In the past, red cheeks have been linked to necrophilia, repressed cannibalism, and even a de-sire for men to experience menstruation! Thankfully, research has come a long way since then, as blushing experts Peter de Jong and Corine Dijk explain. Scientists believe that it evolved as a nonverbal signal to show someone you’re sorry or that you care about what they think. This would have important for our survival in the group, en-suring we didn’t get into a fight or get kicked out the group. Anand Jagatia gets to grips with blushing and other bodily behaviours – including a question from Thai listener Nitcha who wonders why we yawn as well as a question from Mohamed in Ghana and Biana in Trinidad and Tobago who both asked why people scratch their heads when they think. To answer these questions, Anand’s joined by yawning researcher Andrew Gallup and Sophie Scott as well as body language expert Blanca Cobb. Produced by Graihagh Jackson for the BBC World Service.