Sleep Problems? Open Mouth Breathing? Crooked Teeth?
Here’s what’s going on.
“Virtually all aspects of how modern people function and rest are radically different from those of our ancestors.” (Kahn et al., 2020)
Agreed! The focus of this interdisciplinary group of researchers is one seemingly small aspect of the vast differences between our species-typical life course with the species-atypical pathway the modern world is on. They focus on the human jaw.
People in industrialized societies like the USA have multiple jaw related problems. Crooked teeth and sleep apnea are burgeoning. What’s going on?
Jaws started to shrink among those who moved to settlements about ten thousand years ago because of the change in diet from hunter-gatherer civilization. Soft foods of settled agricultural life disrupted the signaling needed by the body for healthy jaw development. But the situation has gotten much worse in the last few centuries.
With the shift from labor centered in the home to labor centered in industrial factories, mothers left the home to work, leaving their babies behind. Babies no longer received the species-normal length of breastfeeding (2.5-8 years). The activity of breastfeeding, using jaw muscles and tongue in particular ways, signals the body to form a healthy jaw. Still today, few children breastfeed during the first year, when jaws receive signals from experience about how to grow.
Bones grow according to gentle and persistent pressure, as Chinese footbinding practices showed. The correct oral posture is to hold the teeth lightly together where the tongue is positioned against the palate.
There was an additional collateral change to babies’ jaw development. Spoon feeding. To speed things along and instead of breastfeeding, busy parents began to use a spoon to feed their babies. It turns out that the most sensitive period for jaw development is the first year of life. Spoon feeding changes the posture of the tongue. The child just sucks and swallows (unlike breastfeeding where the tongue acts like a piston extracting milk from the breast). The authors recommend that spoons not be used until the molars are in. Throughout childhood, vigorous chewing should be encouraged, with limited use of liquid food.
Our species-normal heritage is to breastfeed at the infant’s request day and night for several years and over time in the first 18 months chew food for the infant and put it in their mouth. According to studies of baby-led weaning, babies are interested at five months or so to put things in their mouths. This is a good time to have them sit at the dinner table with big chunks of things (e.g., cucumber sticks) and let them gnaw on them. They won’t eat them, but expand their palate and strengthen their jaws.
Why does jaw strength and size matter? Species-atypical small and weak jaws are associated not only with inadequate room for adult teeth and tongue, but also with sleep problems (e.g., obstructive apnea). Moreover, the longterm effects of a too-small jaw is that the mouth is often kept open “Oral overbreathing alters oral rest posture, thereby the developmental growth of the jaws” (Kahn et al., 2020, p. 760).
Things have only gotten worse for children’s jaw development. Children no longer spend their days outside where there is less exposure to allergens. Instead they are now kept inside of four walls exposing them to concentrated allergens and the spread of infection, and babies are sent to daycare settings where viruses proliferate. Infections plug the nose, again, influencing jaw development. Being congested in the first years of life misdirects jaw development because of extensive mouth breathing.
Living with an untreated respiratory allergy can force the child into mouth breathing which can then result in a “long face syndrome.” The authors include pictures of faces worsening across three generations. The chin is receded, the face develops narrowly downward, nose is crooked, teeth are crooked and can become too long, cheekbones are poorly defined, the airway is restricted, and the normal facial posture is mouth open. (Google the syndrome to see photos. The character Napoleon Dynamite, in a film by the same name, shows this syndrome.)
Obstructive sleep problems means that the flight-fight stress response is activated both when asleep and when awake, raising blood pressure. Cortisol levels are chronically raised, causing inflammation, the root of all disease.
Orthodontics are helpful (I had them). C-PAP machines can help you breathe. But maybe we should think about preventing the problems outlined here.
Modern life has taken us down many unhelpful and even hurtful pathways, away from the nested pathway. Jaw development is yet another side effect of forgetting evolved ancestral wisdom. Understanding jaw development suggests the critical importance of breastfeeding for at least 2.5 years (and not bottle feeding), of spending most of childhood outside, of keeping babies out of daycare settings, and of reexamining what and how we feed children after the first year (besides breastmilk). Whew! Lots of changes need to be made to our unnested lifeways.
References
Kahn, S., Ehrlich, P., Feldman, M., Sapolsky, R., & Wong, S. (2020). The Jaw Epidemic: Recognition, Origins, Cures, and Prevention. Bioscience, 70(9), 759-771. doi: 10.1093/biosci/biaa073
Rapley, G., & Murkett, T. (2019). Baby-led weaning: How to introduce solid foods and help your baby to grow up a happy and confident eater. The Experiment.