Yawning is our body’s way of telling us we’re tired and in need of a nap or a good night’s sleep. When we yawn, we open our mouths wide to suck in a big gulp of air. It helps to oxygenate the brain and makes us feel better. But did you know that bigger yawns could actually mean bigger brains? According to recent research, people who open their mouths wider then they yawn are more likely to have large brains.
A New York psychologist, Andrew Gallup, found that yawning actually helps to promote brain growth, as well as increasing brain activity. The psychologist published a paper that documented the examination of the yawns of 109 animals from 19 different species—everything from humans to mice to walruses to elephants. According to this paper, the average duration of a yawn is an accurate predictor of two things:
- The number of cortical neurons in the brain
- The brain weight
How is this possible? Well, Gallup has been working on a theory for over a decade. This theory, called the thermoregulatory theory of yawning, states that our brains are cooled off when we open our mouths wide and suck in a great lungful of air. This helps to prevent overheating, and a cool brain is one that is better able to send signals between the various portions that make up our thinking box.
But that’s not all. Yawning may also be able to get the brain out of the “default mode”, sort of the lower-power state it enters when you’re not working or thinking. A yawn helps to increase cerebrospinal fluid, which in turn triggers the brain to start paying attention to what’s going on around you.
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Yawning helps to increase the flood of blood to your brain, and it increases the amount of oxygen delivered by that blood. The stretching of your jaw and the deep inhalations helps to reduce the warmed blood in the brain, replacing it with cooler blood that is pumped up from your heart. The open-mouthed yawn also promotes a direct heat exchange with the air around you, helping to cool off your body further.
In the study, the doctor and his assistants timed the length of yawns. The duration varied: anywhere from 6.5 seconds for a human to 0.8 seconds for a mouse. Dogs tend to yawn for 2.4 seconds, cats yawn for just 1.97 seconds, but camels—which tend to be smarter than you’d think—yawn for up to 4.8 seconds.
But jaw size has nothing to do with brain size. It’s the length of the yawn, not the size of the open mouth that affects brain weight and cortical neuron count. The longer the yawn, the better the brain function.
Now, this theory is still very much in its early stages. There is a bit of contention over the accuracy of the theory. Critics disagree with the “yawn to cool off the brain” theory, believing that the amount of cooling isn’t significant.
Be that as it may, the truth is that yawning works. It helps to stimulate brain activity, banish tiredness, and increase blood flow to the brain. According to the research mentioned above, it’s also a great indicator of your brain function. Perhaps the average human is smarter than most animals because of the length of their yawn, or maybe it’s just a coincidence. Either way, it’s a great reason to allow yourself to hold out that yawn for as long as you feel it. It’s a sign your brain is well-developed!