Yawning is a breathing reflex thatoccurs in humans and animals when they are tired or have health problems. Scientists have been trying to explain the reason for yawning for many years, but still cannot come to a consensus. Someone thinks that a long inhalation somehow helps to get rid of fatigue and psychological stress. Some scientists agree that yawning is needed to renew the air in the lungs and oxygenate the blood. However, the most plausible version is that a sharp and deep breath cools the brain - most likely, this helps it work better. Recently, Dutch scientists conducted a large-scale study and put forward strong evidence in favor of this version. Let's see what the researchers learned so much?
What is yawning for?
Results of scientific work carried out by scientistswere published in Science Alert. They were prompted to conduct the study by a hypothesis that was put forward in 2007. It says that living organisms need yawning in order to cool the brain. It follows from this that the larger the brain volume of the animal, the longer it needs to yawn in order to prevent overheating of the most important organ. To test the plausibility of the hypothesis put forward, scientists recorded on video the yawns of 1,300 species of animals. Among them were 55 species of mammals and 46 species of birds.
To their surprise, they actually foundthe relationship between the duration of animal yawns and the volume of their brain. As it turned out, mammals yawn much longer than birds. Winged creatures can afford short breaths due to the fact that their body temperature is much higher than that of other living organisms. While for humans, the normal temperature is 36.6 degrees, for chickens it is about 42 degrees. And in small birds like sparrows, this figure can even reach 45-degree mark. So the brains of birds rarely overheat and it is quite easy to cool it.
How yawning can help cool the braintold ethologist Andrew Gallup. According to him, during a sharp breath when yawning in humans and animals, the muscles in the oral cavity are stretched. During this process, the flow of cold blood to the brain increases, which ensures thermoregulation. It turns out that yawning is a protective mechanism against overheating of the most important organ of living organisms. But is this really the only function?
See also: Why do some people sneeze when looking at the sun?
Other yawning functions
The results of the study do not cancelthat yawning is needed to oxygenate the blood. Observations show that people most often yawn in stuffy rooms - you probably yourself will agree that you very rarely yawn in the fresh air? A sharp influx of oxygen helps us to invigorate and that is why we inhale sharply in a sleepy state. Yawning during stress occurs when we breathe less often when stressed, and the brain sends a signal to the body to yawn in order to restore oxygen levels in the blood.
Read also: 10 unusual defense mechanisms of the human body
Why is yawning contagious?
Another great feature of yawningis that it is contagious. Scientists believe that we repeat one after the other as a result of the activation of mirror neurons. This is the name of the nerve cells that are responsible for empathy and understanding of other people's actions. It can be said that yawning is a side effect of the socialization tool. However, there are people who are completely immune to yawn infestation. As a rule, these are children under 6 years old and people with autism spectrum disorder. Among other people, the susceptibility to yawning is different: someone may start yawning even while reading a text, while someone yawns only when looking at a very close person.
Sometimes yawning is a sign of a problem.with health. For example, it can signal diabetes mellitus - the cells of the body lack glucose and cannot produce energy. Because of this, the person feels tired and the brain tries to wake up by receiving more oxygen. Also, frequent yawning may indicate that a person often experiences sleep apnea, that is, stops breathing for several tens of seconds. Upon awakening, he suffers from oxygen deprivation and therefore often yawns.
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Yawning is one of the phenomena that does not yet lend itself to accurate scientific explanation. You can read about other phenomena of this kind at this link.