Why is Yawning Contagious ?

Yawning is extremely contagious -- 55% of people who witness someone yawn will yawn within five minutes. If a visually impaired person hears a tape of someone yawning, he or she is likely to yawn as well. Face it, the likelihood of you making it to the end of this answer without looking like one of these gaping maws is unlikely.
Yawning is all about consciously analyzing and mimicking other people’s actions.This circuitry is called the “mirror-neuron system,” because it contains a special type of brain cells, or neurons, that become active both when their owner does something, and when he or she senses someone else doing the same thing.

Mirror neurons typically become active when a person consciously imitates an action of someone else, a process associated with learning. But they seem to play no role in yawn contagiousness, the researchers in the new study found. The cells are have no extra activity during contagious yawning compared with during other non-contagious facial movements, they observed.

This does not explain specifically why people will duplicate someone else yawning, but it does suggest that there are brain sections responsible for one’s perception of a yawn. Further, yawning does not begin with the mirror neuron system but instead bypasses it.

Other explanations for why yawning seems contagious include the idea that yawning may have evolved in early man as a way to signal or set up sleep schedules. A contagious yawn meant that perhaps more than one person was tired and people should sleep accordingly.

Since tiredness might indicate a less energetic response to danger, clearly, yawning would mean people should find shelter and get out of danger. Those who yawned and paid attention to it, may have been selected into the species because they got proper sleep and were more alert to danger.

However, the exact mechanism and reasons of why one yawns in response to others yawning is still not clearly understood. The 2005 research may point the way to where to look for more clues about this interesting and automatic human behavior.

worldscience n wisegeek