Who yawns?

Humans are not the only ones to yawn, animals yawn too. However, with the exception of certain high order animals like the chimpanzees, animals don’t manifest contagious yawning. Certain cultures ascribe superstitions to the act of yawning. The most common of these is the belief that it is necessary to cover one's mouth when one is yawning in order to prevent one's soul from escaping the body. The Ancient Greeks believed that yawning was not a sign of boredom, but that a person's soul was trying to escape from its body, so as to rest with the gods in the skies. This belief was also shared by the Mayans. Several superstitions have been concocted regarding the act of yawning and the harm that the act can do to the individual yawning.

Why is yawning contagious?

The proximate cause for contagious yawning may lie with mirror neurons, i.e., neurons in the frontal cortex of certain vertebrates, which upon being exposed to a stimulus from conspecific (same species) and occasionally interspecific organisms, activates the same regions in the brain.
To look at the issue in terms of evolutionary advantage, if there is one at all, yawning might be a herd instinct. Other theories suggest that the yawn serves to synchronize mood in 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. This phenomenon has been observed among various primates. The threat gesture is a way of maintaining order in the primates' social structure. 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."

Is yawning contagious?

The yawn reflex has long been observed to be contagious. In 1508, Erasmus wrote: "One man's yawning makes another yawn" and the French proverbialized the idea to "Un bon bâilleur en fait bâillier deux." ("One good gaper makes two others gape"). Often, if one person yawns, this may cause another person to "sympathetically" yawn. Observing another person's yawning face (especially his/her eyes), even reading, or thinking about yawning, or looking at a yawning picture can cause a person to yawn. Whether or not seeing someone else’s jaws gaping wide gives you the uncontrollable urge to join in may say more about your personality than you realize. Roughly half of people yawn when watching videos of others yawning. Some researchers hypothesize that contagious yawning is more common in people with greater empathy — the ability to recognize and share other people’s emotions — an idea that has gotten quite a bit of press lately. Developmental clues support the empathy theory for contagious yawns. Children younger than about four years old, it seems, yawn spontaneously but don’t catch contagious yawns from adults or from one another.

Why do we yawn?

There is some controversy as to why we yawn and scientists haven't agreed on a single explanation just yet. Some say that yawning may be a means to keep the brain cool. A parallel new theory is that yawning is used for regulation of body temperature. One more suggestion is that yawns are caused by the same chemicals or neurotransmitters in the brain that affect emotions, mood, appetite, and other phenomena. Yet another hypothesis is that yawns are caused by a lack of oxygen in the bloodstream, and that yawn reflex incorporates a "rush of oxygen" to the brain.Most people agree that when hen you are bored, you yawn. Scientists have confirmed this observation by comparing the number of yawns in 17-19 year old students who watched music videos to the number of yawns in students who watched an uninteresting color test bar pattern.

Yawning

According to a medical dictionary, yawning or oscitation is the act of producing a yawn. A yawn is the involuntary opening of mouth often caused by suggestion and accompanied by breathing inward then outward. Repeated yawning can be a sign of drowsiness or depression ("Medical Dictionary," 2009). It is usually a reflex of simultaneous inhalation of air and stretching of the eardrums, followed by exhalation of breath. Pandiculation is the act of stretching and yawning simultaneously. Yawning is generally related to tiredness, stress and boredom. Yawning can also be a powerful non-verbal message with several possible meanings, depending on the circumstances. 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! (Chudler, 2007).