Natural selection has favoured individuals with the capacity to feel bored because they are more likely to discover or create things that improve their survival chances, or to look for a new partner and so spread their genes more widely.
No-one is sure why we yawn. We do know that yawning increases with levels of some of the brain’s neurotransmitters, including dopamine and serotonin, and decreases with levels of the opium-like endorphins.
When you listen to a sad, reflective song, what colour come to mind? How about a happy, jaunty tune? Researchers have now shown that people tend to associate different colours with different songs, depending on how they make us feel.