If one has ever seen someone in close proximity yawn, then one may note the distinct feeling or urge to yawn as well. It is true that between 40-60% of people will automatically find yawning contagious and yawn themselves. The standard answers from scientists as to why people find yawning contagious used to be, “We don’t know, but we have some theories.” Research conducted in 2005 by Finnish scientists, however, may point to preliminary reasons why some find yawning contagious.

When one witnesses someone else yawning, one has a mostly unconscious urge to yawn. People may become conscious of the urge, but scientists suggest the beginning of the yearn to yawn is unconscious. This means that the signal to yawn must bypass a response called the mirror neuron system, which would render yawning in response to someone else a conscious and imitative act. Scientists have often, in the past, suggested that the mirror neuron system causes yawning.

Instead, researchers found that witnessing someone else yawning seems to render inactive the periamygdala sections of the brain. This is a tiny part of the brain on either side of the head that helps interpret things like facial expressions. Thus a conscious response to yawning would be, “Oh, he’s tired.” However, by temporarily blocking such a reading, the response to another person yawning cannot at first be a conscious perception.

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.