Babies and young children are immune to 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. Babies and young children are immune to “catching” yawns, scientists have discovered in new research that is shedding light on how the human brain develops as we grow up.
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.
More recent research has revealed that chimpanzees and even dogs can catch yawns from those around them, including from humans, but little is known about why we yawn and why it appears to be so infectious.
Psychologists at the University of Stirling, however, have now discovered that infants and young children are not prone to the contagious aspect of yawning. Instead, they only ever yawn spontaneously.
Dr Jim Anderson, a reader in psychology at the University of Stirling who led the research, which is published in the Royal Society journal Biological Letters, believes the findings will help to shed new light on how the human brain develops as we grow up and what makes us yawn.
He said: “The exact reason why we yawn isn’t really understood very well at all, but there is no doubt that as adults it is highly contagious.
“People who score highly for empathy are significantly more likely to show contagious yawning. What we know from other research is that one part of the brain that continues to develop through out childhood is the frontal cortex and that the frontal lobes play a role in social decision making and the ability to empathise.
“That would tie in with the gradual development of contagious yawning during childhood.”
In the study, Dr Anderson and his colleague Alisa Millen, studied the yawning behaviour of 22 infants and toddlers while they were shown video footage of other children, adults and animals yawning. They were also shown footage of their mother yawning.
The researchers found that the children did not yawn in reaction to the footage.
In another study Dr Anderson also found that children do not start catching yawning until they reach the age of five years old when a small percentage start being affected.
He said: “With each age group up to the age of 11 years old, there is a higher proportion who will react to video footage of someone yawning.
“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.”