No one has so far been able to determine exactly why and we begin to yawn when we look at someone who yawns.

One theory: yawning is a form of nonverbal communication. For babies, for example, the intense yawning within a group signals that sleep time is typical for the leader (alfa male) to end the ritual with a loud voice, wide-ranging mouth.

If our ancestors used to yawn to communicate with baboon today, then contagious contagion could be a bad, genetically programmed phenomenon.

More important than the question of why yawning is so contagiousness. And sometimes we all do it ten times an hour, more often early in the morning and late in the evening. In fact, swelling begins before birth – the fetus in matter begins to grow already in the 11th week of development.

However, there is little confidence in the mechanism of conquest. Yawning, most likely, does not always show the need for sleep and seems to have nothing to do with the assumption that our body does not have enough oxygen or possesses too much carbon dioxide (which, in theory, may require a deep breath).

This second theory lacks reliability after a 1987 study that has shown volunteers undergo a large intake of oxygen, not less than those exposed to a high concentration of carbon dioxide – which, moreover, do not ring more and more often.

 

Theories of yawning

Here are some of the most lucid theories about yawning – though none of them received a scientific confirmation:

– Yawning spreads our lungs and surrounding tissues, protecting such sensitive lung tissue from cracking. This could explain why we are more often at a time when breathing is “shallow” (when we are tired, when we get bored or when we just get out of bed).

– Shading “distributes” the substance called “surfactant”, a liquid that compliments the tiny air pockets in the lungs and helps them stay open. This substance is a critical substance that allows a newborn to survive “getting out” from the uterus. This theory could explain why the fetus is developing during its development, preparing to begin using its own lungs.

– Yawning spreads the muscles and joints and increases the volume of the heart. Because of this, it prepares the body for an elevated degree of caution, especially after the relieving. This explains why athletes and professional musicians often catch themselves up as they anticipate a sudden increase in activity.

 

Any Sign of disease?

True or false, yawning may also be a sign of disease. As a first signal, intense yawning is very noticeable in people with multiple sclerosis; amyotrophic lateral sclerosis (ALS, also known as Lou Gering’s disease).

Dizziness occurs after a radioactivity injury (as in a case of radiotherapy); is also reported in people receiving Parkinson’s disease therapy.

Rare, yawning at great length may announce the onset of a migraine. On the other hand, itching is commonly seen in schizophrenic patients. It is not clear why these diseases can determine the frequency of yawning in some person.

Researchers have noted that stimulation of some parts of the brain in animals and humans can provoke ingestion. Substances, brain transmitters, can also play a role in yawning.

Therefore, no matter how tender it seemed simple, it is a complex behavior with an uncertain task …

 

Source: http://www.stetoskop.info/Zasto-zevamo-4666-c45-content.htm