By Yin Nwe Ko
The hundreds of human skulls preserved in the Morton Cranial Collection at the Penn Museum in Philadelphia reveal an unexpected mystery about modern health. The collection, one of the world’s largest of its kind, contains specimens from cultures across the globe and spans from the Stone Age to the nineteenth century. While examining the skulls, researchers noticed something remarkable: ancient people almost always had straight teeth, broad jaws, and strong facial structures. Crooked teeth, crowded mouths, and impacted wisdom teeth were extremely rare.
In contrast, modern humans commonly struggle with dental misalignment. Millions of children and adults wear braces, undergo tooth extractions, or receive corrective dental procedures. Orthodontics has become a massive industry, yet the deeper causes of these problems remain controversial.
A New York Times writer once discussed this phenomenon with one of the museum’s modern curators. Looking at ancient skulls with perfect teeth, the writer asked whether she had ever seen crooked teeth in specimens from ancient populations.
“No, not one. Ever,” the curator replied.
The ancient skulls consistently showed edge-to-edge bites, wide dental arches, and room for every tooth, including wisdom teeth. But the situation changed dramatically in skulls over the last two centuries. One nineteenth-century North American woman’s skull displayed a narrow upper jaw, crowded teeth, and a weaker facial structure.
The curator admitted that she had spent years wondering what had changed.
“I always told my students, ‘Something happened 200 years ago, and nobody has an edge-to-edge bite anymore – and I have no idea what,’” she explained.
Anthropologists and dental researchers have proposed many explanations. Some argue that modern diets play a central role. Ancient humans ate tougher, less processed foods that required heavy chewing. This constant use of the jaw during childhood may have stimulated proper growth and development of facial bones.
Modern diets, however, consist largely of soft and processed foods. Children today often eat mashed foods, bread, pasta, cereal, and snacks that require little chewing effort. Critics of modern dietary habits argue that this reduced strain on the jaw prevents it from developing fully, resulting in smaller mouths and crowded teeth.
Despite these observations, mainstream orthodontics often focuses on treatment rather than prevention. The most common explanation given to patients is that crooked teeth are primarily genetic.
“Your teeth are too large for your jaw,” many orthodontic clinics explain.
Some clinics acknowledge that environmental factors such as thumb sucking or mouth breathing may contribute to alignment problems, but these factors are usually considered secondary.
Meanwhile, orthodontic treatment continues to grow rapidly around the world. At any given time, millions of Americans wear braces, and a significant percentage of teenagers eventually receive orthodontic care. In the United Kingdom, hundreds of thousands of young people undergo similar treatments every year. Increasing numbers of adults are also seeking braces and aligners in pursuit of improved smiles.
Dental crowding has become so common that wisdom tooth extraction is practically considered a normal part of growing up. Many teenagers and young adults have their wisdom teeth removed before they even cause symptoms. Some studies suggest that by age thirty, a majority of adults in industrialized societies have undergone wisdom tooth extraction.
To critics, this widespread need for correction raises an important question: if crooked teeth are simply genetic, why did the problem become so common only recently in human history?
One controversial answer comes from Dr John Mew and his son Dr Mike Mew, British orthodontists associated with a field known as orthotropics. Their theories challenge conventional orthodontics and argue that modern lifestyle habits are significantly altering facial development.
According to the Mews, one of the most damaging habits is chronic mouth breathing.
They claim that breathing through the mouth instead of the nose can affect the position of the tongue, the shape of the jaw, and the development of facial bones during childhood. In healthy development, the tongue naturally rests against the roof of the mouth, helping the upper jaw expand outward. However, if children breathe primarily through the mouth, the tongue drops downward, reducing support for proper jaw growth.
The result, according to their theory, is a narrower face, crowded teeth, weaker jawlines, and smaller airways.
The Mews also connects these structural changes to a growing list of modern health problems. They argue that reduced airway size contributes to sleep-disordered breathing, including snoring and obstructive sleep apnoea. Sleep apnea causes repeated interruptions in breathing during sleep and has been associated with serious health risks such as cardiovascular disease, diabetes, depression, poor concentration, and memory problems.
Some researchers have also linked sleep-disordered breathing in children to behavioural issues, learning difficulties, and reduced academic performance. In severe cases, poor sleep quality may affect emotional regulation and cognitive development.
Supporters of orthotropics believe that modern society has underestimated the importance of proper facial development. They argue that correcting underlying breathing habits and encouraging healthy jaw growth during childhood could reduce the need for braces and extractions later in life.
However, the Mews’ views remain highly controversial within mainstream dentistry and orthodontics. Many orthodontists argue that their claims lack sufficient scientific evidence or rely too heavily on anecdotal observations.
The disagreement eventually became intense. In 2017, Britain’s General Dental Council removed John Mew’s license to practice dentistry at the age of eighty-eight. Critics accused him of publicly criticizing established orthodontic methods and promoting ideas considered outside accepted standards.
Despite this opposition, interest in airway health, facial growth, and breathing patterns has continued to grow online and among some health professionals. Social media platforms, podcasts, and alternative health communities frequently discuss topics such as nasal breathing, tongue posture, and facial development.
The debate reflects a larger issue in modern medicine: should healthcare focus mainly on correcting problems after they appear, or should it pay greater attention to prevention and environmental causes?
Ancient skulls suggest that humans once developed strong jaws and straight teeth naturally, without braces or surgery. Something about modern lifestyles appears to have changed that pattern. Whether the causes are diet, breathing habits, genetics, or a combination of many factors, the dramatic rise in dental problems raises important questions about how modern environments shape human health.
For now, orthodontics continues to provide solutions for millions of people seeking healthier or more attractive smiles. Yet the mystery observed in museum collections remains unresolved. Why did our ancestors rarely need braces, while modern populations increasingly depend on them?
The answer may not lie in a single cause but in the cumulative effects of industrialization, processed foods, changing childhood habits, and modern lifestyles. As researchers continue investigating the issue, the history hidden inside ancient skulls may eventually reshape how future generations think about teeth, breathing, and human development.