Question: what makes people yawn

Jen Todd Jones answered on 19 Mar 2013:

Scientists think we yawn because it helps us absorb more oxygen to the lungs which helps keep the brain awake when we’re tired! Although we’re still not sure if this is necessarily the only purpose of a yawn, perhaps when we were still evolving as cavemen hundreds of thousand of years ago we us yawns to signal to others in the tribe that we were tired so that we could coordinate rest – perhaps this is why when we yawn others tend to copy and yawn too!