We Stopped Chewing, and Our Jaws Shrank Too Small for Our Teeth
Within a few generations of soft food, wide jaws gave way to crowded teeth, narrow airways, and mouth breathing.
The Rich Roll Podcast · This Breathing Technique Will TRANSFORM Your Health In DAYSLook at a human skull older than about 400 years and, in Nestor’s account, you will see the same thing every time: perfectly straight teeth set in a wide jaw. Look at us, and about 90 percent of us have crooked teeth, or what dentists call malocclusion, since the jaw never grew large enough to hold all the teeth trying to fit inside it.
James Nestor, author of “Breath,” argues the change happened too fast to be evolution. In his view, it was food. Our ancestors roughly six generations ago ate food that had to be chewed, for about 2 to 3 hours a day. Chewing is exercise. It builds bone and muscle, and it widens the mouth while the face is still growing.
Industrial food removed that work. Think of 1800s England, with its baked goods, canned goods, and pickled foods, all soft and needing almost no chewing. Today, even people who eat salads are nowhere near that old daily total. In Nestor’s argument, vitamins and minerals matter less than consistency.
The timing is what convinced him. Nestor recounts the claim of a researcher in the 1930s who spent 10 years traveling the world and reported the same pattern across cultures in Asia, England, and Africa: once industrial food arrived, roughly half the next generation developed small mouths and crooked teeth. An archaeologist, Robert Corruccini, later documented the shift in about 250 scientific papers. Three generations on, Nestor puts the share at 90 percent.
Most of the shaping, though not all, occurs in early childhood, from ages 1 through 4 or 5, in Nestor’s view. Babies weaned on applesauce and boiled carrots are less likely to get the chewing that builds a wide foundation. Babies weaned on food they must masticate do get that input, which is why Nestor points to the baby-led weaning movement, which moves infants from breastfeeding straight to chewable food, as a return to the older pattern.
A small mouth does more than crowd teeth, Nestor says. The upper palate narrows into a V shape and grows upward, taking space from the sinuses. Air has less room to flow, like water in a narrow pipe. Breathing through the nose gets harder, so people default to the mouth. That was meant to be a backup system, not the main one.
Questions people ask
If I chew more as an adult, will my jaw get wider?
No, not much. In young children the bone is still growing and responds strongly to chewing forces. In adults the shape is largely set, though chewing firm foods can still strengthen the jaw, tongue, and throat muscles that help keep the airway open.
What does baby-led weaning actually look like?
It is an approach where, after about six months and with a pediatrician's guidance, babies feed themselves soft pieces of family foods instead of only smooth purees. Pieces are kept large, soft enough to mash with gums, and low risk for choking, which lets infants practice chewing and swallowing.
Can braces fix a small mouth, or do they make it smaller?
Traditional orthodontics often straightens teeth by removing teeth or pulling the upper jaw back, which can leave the mouth smaller. Airway-focused dentistry tries to do the opposite in growing children: expand the palate and jaw so there is room for all the teeth and for nasal airflow.