Why (yawn) yawning (yawn) is contagious (yawn)

Yawn, and the world yawns with you. New research shows that the sleepy urge really is catching, and that this may be a primitive survival tactic.

Yawn, and the world yawns with you. New research shows that the sleepy urge really is catching, and that this may be a primitive survival tactic.

Brain scanning of volunteers exposed to pictures of people yawning has established that it is contagious and a "synchronised group activity", in the same way that herds of animals and flocks of birds all take flight at the same time.

It has long been thought that copycat yawning was simply imitation, but the research shows that the areas of the brain involved in mimicry were not activated.

"Such synchronisation could be essential for species survival and works without understanding, like when a flock of birds rises to the air as soon as the first bird does when it notices a predator,'' says Dr Martin Schurmann, a Finnish academic who led the international study, reported in this week's edition of the science journal NeuroImage.

Scientists scanned the brains of people as they looked at various videos and pictures, including those of actors yawning. They were not told why they were looking at the images, and the aim was to see which parts of the brain were stimulated by seeing a yawn.

The research shows that six out of 10 people yawn when they see someone else doing the same thing - even when they are not tired. A similar proportion do not even need to see a picture, they will yawn every time they see the word yawn printed on the page.

Just what role yawning has in survival is not clear, but Dr Jim Anderson of Stirling University, an authority in the field, says it may be linked with a desire for empathy.

"The idea with this research is that contagious yawning is something like the very primitive behaviour that you see if birds. If one of them panics, they all panic. It is an automatic response,'' says Dr Anderson, whose own research shows that chimpanzees are also victims of contagious yawning.

"The purpose of it is not known. But we know that yawning itself does have a physical purpose. There have been various suggestions that it increases oxygen, clears the tonsils after eating, equalises ear pressures, and so on. Maybe in our stressed lives we forget to yawn, and when we see someone else doing it, we are reminded subconsciously that it is something we should do.

"I like the idea that is based on some kind of low-level empathy. That we see someone else doing it, we subconsciously think it's a good idea, and we do it.''