The Domino Effect of a Shrinking Skull
I was honored to interview James Nestor, author of the new New York Times bestselling book, Breath. This article is a review of my enlightening discussion with Nestor on our podcast—a must-watch interview.
Are Human Skulls Shrinking?
Sadly, it is true—modern skulls are much narrower than our ancestors’. Dating back 200 to thousands of years ago, a collection of skulls called the Morton Collection has documented a dramatic change in the structure of the human skull.
In Nestor’s new book, Breath, he spends years researching the causes and effects of this phenomenon. Our recent ancestors had much larger and bolder forward-facing jaws with wider mouths, expansive palates, larger airways, and nasal apertures twice the size of a modern human.1
With such a wide face, jaw, palate, and airways, breathing through the nose was effortless and obligatory. Our ancestors breathed through their noses and ate and spoke through their mouths, as we should be doing today.
The Shrinking Jaw
One explanation for this shift in our skulls is that our hunter-gatherer ancestors chewed some four to five hours a day, chomping on tough fibrous tubers, veggies, seed grasses, and meats. Chewing stress releases stem cells in the jaw and cranial bones that boost bone density, widen the jaw, and make us look and breathe better.2
The introduction of soft food, a trend away from nursing babies, and the forgotten wisdom of teaching children how to keep their mouths shut while they sleep has led to an epidemic of crooked teeth, breathing problems, unnecessarily pulling wisdom teeth and a litany of negative side effects associated with a lifetime of shallow upper-chest mouth breathing.
Negative Effects of Mouth Breathing1,4
- sleep apnea (and all its related effects)
Surprisingly, all collections of ancient skulls show larger airways, wider jaws, and straight teeth. Today, as a result of a diet of soft food, some 90% of the population have some sort of malocclusion, aka crooked teeth.3
Early orthodontists knew the mouths of babes were getting smaller—too small to fit all their teeth. Instead of pulling wisdom teeth to make room, and bracing them into place as dentists and orthodontists do today, they devised oropharyngeal devices to widen the jaw and spread the palate open, so as to open the airways once again.
Today, this technique is called functional orthodontics and is making a resurgence. Parents are demanding better from their dentists and orthodontists by restoring oropharyngeal function, rather than just pulling and straightening teeth.
The Lost Palate
As jaws narrow and airways shrink, mouths are forced to open, allowing the tongue to fall into the lower palate to make room in the mouth for breathing. Without the tongue pressed up onto the soft palate (as happens with nose breathing), the soft palate narrows, airways narrow, and the palate becomes V-shaped, jamming the sinuses together instead of keeping them flat and wide. Use a clean thumb to see if your upper hard palate is an upside-down V-shape, U shape, or flat.
Normally, with nose breathing, the tongue is forced to the upper palate, and that keeps the palate wide and flat. Nursing and suckling have the same effect. Both, along with chewing, keep the palate wide, which, in turn, keeps the airways large and open—one reason why nose breathing should be your preferred style.
As the face narrows and airways shrink, researchers find a strong link between chronic mouth breathing, snoring, sleep apnea, cognitive concerns, and breathing issues. Studies at Stanford University are starting to reproduce clinical findings that nose breathing during sleep can reverse and prevent sleep apnea.
Early Nose Breathing Research
In 1986, I started writing my book Body, Mind, and Sport on the benefits of nose-breathing exercise. In 1992, we did a study comparing nose and mouth breathing during exercise and later published that study in the International Journal of Neuroscience. Here is what we found:
Benefits of Nose-Breathing Exercise (as Compared to Mouth-Breathing Exercise)5,6
- Improved lower lung gas exchange
- Improved brainwave coherence
- Increased alpha wave activity
- Decreased perceived exertion or stress during exercise
- Increased endurance
- Increased parasympathetic activity
- Lower and more efficient breathing rates
- Nose breathing may reduce stress, and thus deliver numerous health benefits linked to increased parasympathetic activity
Many other profound health-promoting pathways from nose breathing are being discovered, and there are possibly even more on the horizon as more studies are done!
Benefits of Nose Breathing
- Nose breathing boosts nitric oxide. Nitric oxide is a powerful immune-boosting molecule produced in the sinuses during nose (not mouth) breathing. Discovery of this molecule earned the Nobel Prize in Chemistry as a result of its important health benefits.8
- Nose breathing activates the vagus nerve, which triggers the rest, digest, and destress nervous system response.1,2 The vagus nerve is also the main pathway used by the gut-brain axis, linking the microbiome with brain, mood, and cognitive function.7
- Deep nose breathing that activates the parasympathetic nervous system also stimulates baroreflexes in blood vessels mediated through emotional centers in the brain. For example, your blood pressure will go up when you are under emotional stress. This effect not only supports healthy blood pressure, but is also linked to emotional resiliency and mood stability.7
Relearning How to Nose Breathe
The best ways to start the process of relearning how to nose breath is by:
- Nose breathe during exercise.
- Sleep with mouth closed.
- Slow breathe, at a rate of six breaths per minute.
- Stop overbreathing.
- Practice pratiloma, an Ayurvedic breathing technique to strengthen the diaphragm.
What do you think about the changes in the human skull, specifically the shrinking of the jaw, palate, and nasal cavities? What are you doing to ensure that you can breathe optimally?