Everybody knows that yawns are contagious
There seems to be no easy explanation for this. Atleast one scientist, Dr. Robert Provine, professor of psychology at University of Maryland, spent time researching this topic. He devoted several years to the yawn phenomenon
There is very little research on yawning because for most people yawning is not a problem.
Everyone yawns - babies, kids, teenagers, adults. Some birds, reptiles and most mammals also yawn. However, the reason why we yawn is a bit of a mystery.
Here are a few things that are known about yawns:
- The average duration of a yawn is about 6 seconds.
- In humans, the earliest occurrence of a yawn happens at about 11 weeks after conception - that's BEFORE the baby is born!
- Yawns become contagious to people between the first and second years of life.
A part of the brain that plays an important role in yawning is the hypothalamus. Research has shown that some neurotransmitters (for example, dopamine, excitatory amino acids, nitric oxide) and neuropeptides increase yawning if injected in the hypothalamus of animals.
Dr. Robert Provine says:
The contagiousness of yawns suggests that we've inherited a mechanism for the perception of and triggering of yawns.
He theorizes the infectious yawn, catching only in humans, evolved for a purpose.
It is possible that yawns are contagious because at one time in evolutionary history, the yawn served to coordinate the social behavior of a group of animals. When one member of the group yawned to signal an event, all the other members of the group also yawned. Yawns may still be contagious these days because of a leftover response (a vestigial response) that is not used anymore. None of this has been proven true and yawns are still one of the mysteries of the mind.
1. Provine, R.R. Contagious yawning and infant imitation. Bulletin Psychonomic Soc., 27:125-126, 1989.
2. Provine, R.R. Yawning: effects of stimulus interest. Bulletin Psychonomic Soc., 24:437-438, 1986.
3. Provine, R.R. Faces as releasers of contagious yawning: an approach to face detection using normal human subjects. Bulletin Psychonomic Soc., 27:211-214, 1989.
4. Provine, R.R. Yawning as a sterotyped action pattern and releasing stimulus. Ethology, 72:109-122, 1986.
5. Provine, R.R., Hamernik, H.B. and Curchack, B.B. Yawning: relation to sleeping and stretching in humans. Ethology, 76:152-160, 1987.
6. Edmonton Public Library