Contagiousness
The yawn reflex is often described as contagious: if one person yawns, this will cause another person to "sympathetically" yawn.
[4][5] Observing another person's yawning face (especially his/her eyes), or even reading about or thinking about yawning, can cause a person to yawn.
[4][6]The
proximate cause for contagious yawning may lie with
mirror neurons, i.e., neurons in the
frontal cortex of certain vert, which upon being exposed to a stimulus from
conspecific (same species) and occasionally interspecific organisms, activates the same regions in the brain.
[7] Mirror neurons have been proposed as a driving force for
imitation which lies at the root of much human learning, e.g.,
language acquisition. Yawning may be an offshoot of the same imitative impulse. A 2007 study found that children ter seeing videos of other people yawning; this supports the claim that contagious yawning is based on the capacity for empathy.
[8]
To look at the issue in terms of evolutionary advantage, if there is one at all, yawning might be a
herd instinct.
[9] Other theories suggest that the yawn serves to synchronize mood
gregarious animals, similar to the howling of the
wolf pack. It signals tiredness to other members of the group in order to synchronize sleeping patterns and periods of. This phenomenon has been observed among various
primates. The threat gesture is a way of maintaining order in the primates' social structure. Specific studies were conducted on chimpanzees
[10] and stumptail macaques
[11]. A group of these animals was shown a video of other conspecifics yawning; both species yawned as well. This helps to partly confirm a yawn's "contagiousness."
Gordon Gallup, who hypothesizes that yawning may be a means of keeping the brain cool, also hypothesizes that "contagious" yawning may be a survival instinct inherited from our evolutionary past. "During human evolutionary history when we were subject to predation and attacks by other groups, if everybody yawns in response to seeing someone yawn, the whole group becomes much more vigilant, and much better at being able to detect danger."
[1]
