(ORDO NEWS) — Yawning is a very ancient reflex response that has been observed in a wide variety of vertebrates. In a new article, an evolutionary biologist from the United States analyzed a lot of data and concluded that yawning is necessary so that animals living in a group do not lose their vigilance.
Everyone yawns – not only people, but also a wide variety of vertebrates, from reptiles and birds to humans. However, in the new article, the occurrence of yawning is completely associated with the appearance of the first jaws – in this case, even fish can yawn.
Therefore, a simple reflex act has deep evolutionary roots and some specific meaning. No wonder Charles Darwin became interested in this phenomenon, reflecting on his evolutionary teachings.
Yawning is a stereotypical behavior, that is, it repeats itself in the same way from time to time and is very similar in different individuals.
As a rule, both the duration of yawns, the interval between them, and some of their variety are universal.
Thanks to this, scientists even identified three phases of yawning: involuntary and strong inspiration; a sharp contraction of the muscles with a tilt of the head and squinting; finally, passive relaxation.
The physiological significance of spontaneous yawning is generally clear: it improves cerebral circulation and helps to cool the brain.
However, social interactions associated with yawning are much more difficult to study. The fact is that in social animals (living in a group and constantly interacting with each other), yawning can be very contagious.
In this case, the sight of a yawning tribesman causes an irresistible desire to yawn or some other reaction in the observer.
Biologists believe that mirror neurons are involved in this. Obviously, all these difficulties with yawning arose for a reason and were created by evolution in order to somehow regulate interactions within the group.
To deal with this question, evolutionary biologist at the Polytechnic Institute of the State University of New York (USA), Andrew Gallup (Andrew Gallup), in an article in the journal Animal Behavior , analyzed numerous publications and tried to bring them together, highlighting the most important social aspects of yawning.
The scientist drew attention to a variety of works on the biology of behavior, psychology and neuroscience. After reviewing many hypotheses and entertaining examples to explain yawning, from ostriches to dolphins, Dr. Gallup concluded that yawning maintains alertness and overall activity in a group of individuals. Thus, a simple reflex allows you to synchronize and / or coordinate their interactions.
The scientist notes the importance of physiological changes (circulation of the brain and its cooling), as well as the fact that yawning is associated with switching activity – that is, a change in the type of activity (state change), transition to another environment, and so on.
In this case, the yawn of one animal communicates its relaxed state to others and puts them in a slightly alert (more attentive and active) state. As a result, the group as a whole maintains vigilance and defends itself more successfully from dangers.
In this vein, the author also explains the contagiousness of yawning of one animal for representatives of other species.
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