Human jaws are shrinking, and they are shrinking faster than genetically possible. This is a true epidemic that we need to be talking about on a greater scale. Our health and lives depend on it.
In our modern society, the majority of people that you encounter went through a period of orthodontic treatment in their teens, or at some point in their lives. It has become normalized to eventually endure a few years of braces to correct crooked teeth and misaligned jaws (also known as malocclusion).
If you asked your grandparents, they would likely say that due to lack of technology and awareness, their peers were not so lucky to have access to an orthodontist in their area. Though this is partly true, it's likely that your grandparents' generation didn't NEED orthodontic treatment to the same degree that our children are requiring it today.
Researchers have studied the skulls of our ancestors, finding that with each generation, our jaws are getting smaller.
Cavemen didn't have crooked teeth
In fact, anthropologists have found that humans who lived thousands of years ago as hunter-gatherers had much larger jaws that accommodated all of their teeth WITHOUT crowding. These pre-industrialized humans also didn't have the tooth decay that we see so commonly today!
Though these changes have previously been blamed on genetics, researchers argue that the rate of which these changes are occurring is too fast to be a result of genes alone. Most of these major changes to our jaws have really only occurred in the past 300 years; which, from an evolutionary standpoint, is not a very long time.
What went wrong?
What really changed from then until now is a combination of dietary and environmental changes, as well as changes to cultural norms. Over time, these lifestyle modifications can make small changes to our gene expression and is referred to as Epigenetic changes. This doesn't mean that our actual DNA sequence is changing-- Epigenetic changes are a result of environmental influences that cause certain genes to turn on and off. This can explain why over time, we are even being born with characteristics such as smaller jaws as a result of the changing habits of our parents and grandparents.
Before industrialization, humans did not eat soft, processed foods at all. Over the years, the consumption of soft, processed foods have progressively increased. The generations before us needed to eat foods that required chewing from an early age. Chewing hard foods during development helps to build muscle in the jaw which encourages the jaws to grow wider. Another contributing factor is the rise in bottle feeding and pacifier use which both can negatively affect the way that the jaws grow.
Environmental & Cultural Norms
Believe it or not, living and sleeping indoors also contributed to our shrinking jaws! When humans spent most of their time outdoors, they were exposed much less to dust and allergens. When we spend most of our time indoors, the dust and allergens are much more contained, making us more susceptible to nasal congestion. Our outdoor air quality has also changed with the increase in pollution. Humans today are mouth breathing more than ever because of this.
Another contributor to mouth breathing? Sleeping on soft mattresses and pillows. Our sleeping environments, while they seem much more cozy these days, may actually be affecting our sleep position and making it more likely for our airway to be compromised overnight. (Don't worry, I'm not going to suggest ditching your bed!)
Mouth breathing changes the way that our face grows.
In order for the jaw, face and airway to develop correctly, we must nasal breathe with proper oral rest posture-- day and night. This means that our tongue must rest in the roof of the mouth with the lips closed. The balance of force from the tongue exerting pressure on the roof of the mouth and the lips and cheeks closed around it, guides the palate to grow into a wide, flat, U shape that accommodates all of the teeth without crowding.
The face grows through the "path of least resistance". If the tongue doesn't make contact with the roof of the mouth and the mouth is open at rest, the face tends to grow downward in a vertical direction. This is where we see narrow jaws, v-shaped high palates, sometimes gummy smiles, a set back jaw and crooked teeth.
A Small Jaw = A Small Airway
If the jaws are narrow, there isn't enough room in the mouth to house the tongue. The tongue is then forced to take up space in the upper airway, narrowing the space that we have to breathe through.
Our body will always prioritize breathing. During the day, we may compensate for this by adopting poor head and neck posture, subconsciously trying to open the airway. We may mouth breathe even more because of this, or develop a habit of clenching and thrusting the tongue forward.
Overnight is even more problematic. When we sleep, our body will try to protect our airway to keep us breathing while we sleep. Instead of entering into deep, restorative levels of sleep, our body will stay in a state of fight or flight, resulting in poor sleep quality and sometimes aggressive teeth grinding to open the airway. Whether the airway is narrowed or obstructed during sleep, our bodies will react. Compromised breathing during sleep is referred to as Sleep Disordered Breathing.
Many modern diseases are a result of Sleep Disordered Breathing
The sleep deprivation induced by Sleep Disordered Breathing has been linked to many modern day health concerns such as heart disease, cancer, high blood pressure, Alzheimer's, anxiety, depression and ADHD.
We can change the trajectory of this Epidemic
Unfortunately, we are approximately 7 generations into these Epigenetic changes. It's going to take a massive shift in mindset and lifestyle changes to correct the trajectory, but it is possible. We can help our children now to re-direct their jaw development through changes in diet, lifestyle, habits and changing our approach to orthodontic treatment by intervening earlier and focusing on expanding the jaws.
Myofunctional Therapy also plays an important role in re-directing jaw and facial development. I would argue that connecting with a Myofunctional Therapist should be your first step for children and adults (as a Myofunctional Therapist, I realize that I'm probably biased in this opinion!). Myofunctional Therapy focusses on establishing nasal breathing habits and correct oral rest posture which are absolutely necessary to re-direct jaw development in a lasting way.
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Information Cited From:
University, S. (2020, July 22). The toll of shrinking jaws on human health. Stanford News. Retrieved August 23, 2022, from https://news.stanford.edu/2020/07/21/toll-shrinking-jaws-human-health/
University, S. (2018, April 11). Paul Ehrlich on the problems of the modern jaw. Stanford News. Retrieved August 23, 2022, from https://news.stanford.edu/2018/04/10/paul-ehrlich-problems-modern-jaw/
Kahn, S., Ehrlich, P., Feldman, M., Sapolsky, R., & Wong, S. (2020, July 22). Jaw epidemic: Recognition, origins, cures, and prevention. OUP Academic. Retrieved August 23, 2022, from https://academic.oup.com/bioscience/article/70/9/759/5872832?login=false
These are some great books that are written on this topic:
Jaws, By Sandra Khan & Paul Ehrlich
Breath, By James Nestor
6 Foot Tiger, 3 Food Cage. By Dr. Felix Liau