What is this strange and contagious thing that we do when we are tired? Let’s look at the science behind the yawn phenomenon and try to shed some light on the burning question – “Why do we yawn?”
Yawning has to do with the ability of the human brain to empathize with other humans. The interesting thing is that we are not the only ones doing it. The act of yawning occurs in almost every vertebrate, even little bunnies make yawning motions really often.
Contagious yawning has been spotted in chimpanzees, dogs, cats, baboons, leopards, seals and a lot of other different species. ( Not forgetting about humans of course. ) Science doesn’t think that infants are subjects to contagious yawning, nor people with certain levels autism, suggesting that this is a social behavior.
But, why do we do it in general?
First, this is an involuntary action controlled by our hypothalamus. During the yawn we open our mouths wide, we pulse our sinuses, we take in a large amount of air that expand our chest cavity, pull down our diaphragm, fill our lungs and slightly exhale.
The act itself is usually associated with being tired or as a symbol of boredom in humans. In animals however, yawning can be linked with sexual arousal, fear, uncertainty, mating rituals and as a warning sign to other animals.
Science has a number of competing theories on why we yawn.
- The first recorded theory was from Hippocrates. He theorized that was a way to get good air in and bad air out of the human body.
While yes, the little-used lower lobes of the lungs are filled during that process, research has shown that the function has little to do with filling the lungs with oxygen.
- In the seventeenth and eighteenth centuries doctors thought that it was a way to regulate the heart rate and the amount of oxygen in the blood.
Yes, yawning does suck in a lot of air, but tests have shown that the heart rate, sweating and electrical activity in the brain does not improve post/beyond. Plus, patients who are given oxygenated air neither yawn more or less from those who are breathing air with normal amount of oxygen. Thus, showing that we are not trying to fix a blood O2 problem when we do it.
- Some psychologists believe that the yawn is there to display our level of alertness to members of our social group.
Think about it like a herd mentality, it’s important to know who is the most alert and when. This outward expression of sleepiness can also help regulate circadian rhythms within a pack.
- The current prevailing theory has to do with how the sinuses behave during the process.
They are rapidly pumping air across the front of the brain, so maybe, the yawn is the brain version of a cooling system. Helping our CPU to stay cool and not overheat.
A study, in evolutionary psychology, discovered that holding a cold pack to the head decreased contagious yawning by 32%.
Mirror neurons may also be the cause for some yawns.
Mirror neurons are responsible for learning, relating to others and self-awareness. When we see someone yawn they become activated and as a consequence we just hit the copy button on that action.