No human being on earth has never yawned in their life, yet science still does not have a definitive answer to the cause of yawning. Some theories suggest that it is used to regulate the temperature of the brain. However, yawning as a response to oxygen deprivation has been dismissed by researchers, as has the boredom-sleep theory. According to this view, we yawn and it is contagious because it is how we keep ourselves and our mates alert, just like animals living in packs. Yawning is often accompanied by the need to stretch. These two activities, done together, really keep you alert, so that when danger strikes, animals can react faster, and so can we – even if the danger is just boredom. (Mihály Munkácsy: Yawning Apprentice)