Research suggests children's jaws are smaller today than in previous generations. Breathing patterns, diet, and tongue posture — not just genetics — may shape how the jaw and airway develop during childhood.
Short answer
Research suggests that jaw underdevelopment and dental crowding are more prevalent today than in earlier generations — a pattern documented in both archaeological records and clinical data. Contributing factors include softer modern diets, reduced chewing demand, and widespread mouth breathing, all of which reduce the functional stimulus that guides proper jaw development during childhood. The evidence points to environmental and functional causes alongside genetic ones.
Many parents are told that their child simply has crooked teeth or not enough room for the teeth. But an important question is often overlooked: why do so many children today appear to have less room for their teeth in the first place?
Research from anthropology, orthodontics, craniofacial growth science, and sleep medicine suggests that jaw underdevelopment may be increasingly common in modern populations. A combination of environmental and functional factors may influence how the maxilla and mandible develop during childhood.
This page summarizes the leading ideas researchers have proposed to explain why jaws may be smaller or less developed today.
What did anthropologists discover about jaw size?
When anthropologists studied skulls from ancient populations, they found something surprising: dental crowding and narrow arches were far less common than they are today.
Traditional populations who consumed tougher foods and relied heavily on chewing tended to develop broader dental arches and more space for their teeth.
Modern populations, by contrast, often show higher rates of crowding, malocclusion, and narrower jaw structures.
These observations led researchers to ask whether environmental changes may influence facial development.
How does diet influence jaw development?
One major difference between ancient and modern populations is diet.
Traditional diets required much more chewing. Harder foods, fibrous plants, and less processed meals created greater mechanical demands on the jaw muscles and bones.
Modern diets are generally softer and more processed. Some researchers believe reduced chewing forces during childhood may influence how the jaws develop.
While diet alone does not explain all differences in facial growth, it may be one of several contributing factors.
How does mouth breathing affect airway and facial development?
Breathing patterns may also influence facial growth.
Children who consistently breathe through their mouths rather than their noses may develop different facial growth patterns over time.
Research has shown that chronic mouth breathing is associated with longer facial patterns, narrower upper jaws, and altered tongue posture.
Airway obstruction, enlarged tonsils, allergies, and other factors may contribute to these breathing patterns during childhood.
How does tongue posture affect jaw development?
The tongue plays an important role in shaping the upper jaw during development.
When the tongue rests properly against the palate, it may help support healthy arch development.
If the tongue sits low in the mouth or if oral posture is altered, the upper jaw may develop differently.
Researchers studying craniofacial growth often consider tongue posture, swallowing patterns, and oral muscle function when evaluating facial development.
Why does the direction of facial growth matter?
Facial growth does not occur only in terms of size. The direction of growth also matters.
Balanced forward growth of the maxilla and midface tends to support facial structure and airway form.
In some individuals, growth occurs more vertically, which may contribute to longer facial patterns, narrower arches, and different jaw relationships.
Understanding growth direction is an important part of evaluating facial development.
What does this research mean for parents?
Parents often notice early signs that something about facial development may not be ideal.
Common observations include crowded teeth, narrow smiles, mouth breathing, snoring, or restless sleep.
These signs do not always indicate a serious problem, but they may suggest that facial growth deserves closer evaluation.
How does the Airway & Facial Growth framework approach this?
The Airway & Facial Growth framework focuses on evaluating how the maxilla, mandible, airway, and facial growth patterns develop together.
Instead of looking only at tooth alignment, this perspective considers how growth direction, airway function, oral posture, and skeletal development interact over time.
Understanding these relationships may help guide more comprehensive approaches to evaluating facial growth.