Over time, humans developed some pretty interesting reflexes to help with their survival. For example, on Tuesday, I briefly touched on why humans blink and sneeze—and when such reflexes are normal.
So, today, let’s talk about two more important, primal reflexes…
Yawning refreshes the brain
The next time you’re feeling sleepy in a work meeting (on a computer screen) or when driving, don’t try to hold back that yawn, as modern science shows that yawning serves three important roles in the body.
First, it helps support healthy respiration. In fact, when your body is running low on oxygen, a yawn forces deep inhalation and exhalation. This action increases the delivery of oxygen into the lungs and bloodstream. And it clears out carbon dioxide. Second, yawning increases your heartrate, which, again, helps deliver more blood, oxygen, and nutrients to the brain and the rest of the body.
Together, these two actions may help you to stay alert for longer. Which is as critical a survival tool now as it was for ancient humans.
And now, scientists recently found a third benefit to yawning…
Yawning “cools” the brain
The brain is actually the most energy-consuming organ in the body—taking 40 percent of total metabolic energy. And all that extra blood flow and metabolic activity can “heat up” your brain and require an extra mechanism to cool it down.
That’s where yawning comes in…
When you yawn, your mouth brings in cool air, lowering the temperature in your head. Plus, yawning stretches the jaw and skull muscles (and increases heartrate), sending an influx of fresh, cooled blood flow to the brain. This cooling process also seems to help a sluggish brain grow more alert.
Remember, early humans had larger jaws than we do today, which meant this ancient reflex probably had a bigger impact millions of years ago. (The larger jaw also had more room for teeth—which were needed more with the earlier human diet. As we evolved, our jaws got smaller, but the number of teeth stayed the same, including what we now call “wisdom teeth.”)
In the end, it seems when your brain needs some extra focus or stimulation, the cool-down of a yawn refreshes the mind. Which explains why boredom, drowsiness, inactivity, anxiety, and hunger can all trigger yawning.
Of course, yawning can be contagious among humans. You may even notice your dog mirroring your yawn! (Dogs developed this unique behavior after living in close, domesticated relationships with humans over thousands of years. It helps them communicate with you.)
Now—let’s move onto another primal reflex that has some surprising health benefits…
We inherited goosebumps from our animal ancestors
Goosebumps (or goose pimples)—known scientifically as piloerection—are caused by a contraction of the small muscles attached to hair follicles in your skin. This action pulls on the surface of the skin, causing the tiny hairs to stand up straight. And it creates an appearance on the skin looking like that of a plucked bird.
Of course, historically, many humans had thicker hair and pushing it upright created a zone of insulation around the skin to help keep the body warmer. It also made the silhouette of the body look bigger, which might be interpreted as a threat to a predator or competitor.
You can also produce goosebumps when experiencing a wide range of strong feelings and emotional reactions. For example, you may get them when you’re feeling scared or startled, as part of your primal fight-or-flight response. You can also produce them when you’re feeling surprised, emotionally or spiritually aroused, or excited.
Interestingly, about 20 to 45 percent of people don’t experience goosebumps. And, apparently, your emotional type has a lot to do with it. For example, people who don’t produce goosebumps probably have a “thicker” emotional type—or “thicker” skin, so to speak. (You can learn more about your emotional type by taking this short quiz or by reading my book called, Your Emotional Type.)
Personally, I think both yawning and goosebumps also describe the range of possible reactions to my writing—from yawning (not good writing) to goosebumps (great writing).
“Medical Mysteries: 4 Strange Things Your Body Does.” Augusta Health, 8/7/18. (augustahealth.com/health-focused/medical-mysteries-4-strange-things-your-body-does)