Humans aren't alone when it comes to yawning — all vertebrates do it too, including fish, amphibians, reptiles, birds and mammals. But why? The "evolutionarily ancient" act of yawning likely serves a ...

In the past, many scientists believed that only mammals and birds could feel or think in complex ways. Reptiles, fish, and insects were seen as simple creatures that reacted purely on instinct. But ...

Louise Gentle does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond ...