Babies and young children are immune from 'catching' yawns

... A new study ... has revealed that babies and young children are immune to "catching" yawns until they reach the age of five years old. ...

The surprising findings have shed new light on this mysterious phenomenon, which scientists describe as contagious yawning.

It has been known for decades that yawning can be infectious, leaving adults unable to stile a one if they see someone else opening their mouths wide in a yawning action.

"At the age of 11 years old, it reaches the same levels we would find in adults."

The exact reason why we yawn is still poorly understood. It is commonly thought to be a reaction to low levels of oxygen in the blood sparking a yawn to fill the lungs with air and so increase oxygen intake.

The scientific evidence for this, however, is poor and even breathing in extra oxygen makes no difference to yawning behaviour.

Other research has suggested that yawning can help to increase alertness in the brain or helps to cool the brain. Yawning can also help to equalise pressure in the ears.

There is now growing evidence, however, that yawning may be a social cue that communicates a message. Anthropologists have suggested it might have evolved as a way of signifying that it is time to go to bed. There are even suggestions that it might have developed a sign of sexual attraction rather than the desire to sleep.

Dr Anderson said: "I don't think there is one primary function, but as adults we have a natural tendency to inhibit yawning because it is seen as being impolite. The contagious yawning might just that our brains see someone else doing it and so it becomes acceptable." ...

via Babies and young children are immune from 'catching' yawns - Telegraph.