In last Thursday’s post, “A Modern World of Endemic Jaw Dysfunction” I claimed that human jaws (especially the upper jaw) are typically now malformed because of the softness of our modern diets. Today, let me back that up by what James Nestor says about this in his book Breath. (Every quotation below is from that book, with different passages separate by several blank lines.) Key points:

First, the skulls of those who ate traditional diets are well-formed

A few months before the Stanford experiment, I flew to Philadelphia to visit Dr. Marianna Evans, an orthodontist and dental researcher who’d spent the last several years looking into the mouths of human skulls, both ancient and modern. We were standing in the basement of the University of Pennsylvania Museum of Archaeology and Anthropology, surrounded by several hundred specimens. …

The skulls ranged from 200 to thousands of years old. They were part of the Morton Collection, named after a racist scientist named Samuel Morton, who, starting in the 1830s, collected skeletons in a failed attempt to prove the superiority of the Caucasian race. The only positive outcome of Morton’s work is the skulls he spent two decades gathering, which now provide a snapshot of how people used to look and breathe.

Where Morton claimed to see inferior races and genetic “degradation,” Evans discovered something close to perfection. To demonstrate what she meant, she walked over to a cabinet and retrieved a skull marked Parsee, for Persian, from behind the protective glass. She wiped bone dust on the sleeve of her cashmere sweater and ran a neatly trimmed fingernail along its jaw and face.

“These are twice as large as they are today,” she said in a staccato Ukrainian accent. She was pointing at the nasal apertures, the two holes in the back of the throat that connect to the nasal passages. She turned the skull around so it was staring at us. “So wide and pronounced,” she said approvingly.

Second, the airways are better and the teeth are straighter in ancient than in modern skulls:

Every one of the ancient skulls was identical to the Parsee sample. They all had enormous forward-facing jaws. They had expansive sinus cavities and broad mouths. And, bizarrely, even though none of the ancient people ever flossed, or brushed, or saw a dentist, they all had straight teeth.

The forward facial growth and large mouths also created wider airways. These people very likely never snored or had sleep apnea or sinusitis or many other chronic respiratory problems that affect modern populations. They did not because they could not. Their skulls were far too large, and their airways too wide for anything to block them. They breathed easy. Nearly all ancient humans shared this forward structure—not just in the Morton Collection, but everywhere around the world. This remained true from the time when Homo sapiens first appeared, some 300,000 years ago, to just a few hundred years ago.

Evans and Boyd then compared the ancient skulls to the modern skulls of their own patients and others. Every modern skull had the opposite growth pattern, meaning the angles of the Frankfort plane and N-perpendicular were reversed: chins had recessed behind foreheads, jaws were slumped back, sinuses shrunken. All the modern skulls showed some degree of crooked teeth.

Of the 5,400 different species of mammals on the planet, humans are now the only ones to routinely have misaligned jaws, overbites, underbites, and snaggled teeth, a condition formally called malocclusion.

Third, these changes can plausibly be attributed to changes in what people eat:

Twelve thousand years ago, humans in Southwest Asia and the Fertile Crescent in the Eastern Mediterranean stopped gathering wild roots and vegetables and hunting game, as they had for hundreds of thousands of years. They started growing their food. These were the first farming cultures, and in these primitive communities, humans suffered from the first widespread instances of crooked teeth and deformed mouths.

It wasn’t terrible at first. While one farming culture was plagued by facial and mouth deformities, another hundreds of miles away seemed not to suffer at all. Crooked teeth and all the breathing problems that come with them seemed totally random.

Then, about 300 years ago, these maladies went viral. Suddenly, all at once, much of the world’s population began to suffer. Their mouths shrank, faces grew flatter, and sinuses plugged.

…

… the changes triggered by the rapid industrialization of farmed foods were severely damaging. Within just a few generations of eating this stuff, modern humans became the worst breathers in Homo history, the worst breathers in the animal kingdom.

… for the first time in history, humans could spend their entire lives eating nothing but processed food—nothing fresh, nothing raw, nothing natural. Millions did. Over the next few centuries, food would become more and more refined. Advances in milling removed the germ and bran from rice, leaving only the starchy white seed. Roller mills (and, later, steam mills) ripped the germ and bran from wheat, leaving only a soft, white flour. Meats, fruits, and vegetables were canned and bottled. All these methods extended the shelf life of foods and made them more accessible to the public. But they also made foods mushy and soft. Sugar, which was once a prized commodity of the wealthy, became increasingly common and cheap.

…

The human face began rapidly deteriorating, too. Mouths shrank and facial bones grew stunted. Dental disease became rampant, and the incidence of crooked teeth and jaws increased tenfold in the Industrial Age. Our mouths got so bad, so overcrowded, that it became common to have teeth removed altogether.

Fourth, many aspects of people’s diets changed, but don’t neglect the simple change in the amount of chewing:

Our ancient ancestors chewed for hours a day, every day. And because they chewed so much, their mouths, teeth, throats, and faces grew to be wide and strong and pronounced. Food in industrialized societies was so processed that it hardly required any chewing at all.

This is why so many of those skulls I’d examined in the Paris ossuary had narrow faces and crooked teeth. It’s one of the reasons so many of us snore today, why our noses are stuffed, our airways clogged. Why we need sprays, pills, or surgical drilling just to get a breath of fresh air.

Conclusion: Orthodontists who aren’t aware of this change in the development of the human jaw (especially upper jaw) compared to a few hundred years ago are badly trained. It seems more likely than not that any explanation of this change in the development of the human jaw over the last few hundred years would have important implications for how orthodontics should be done; if jaws can become malformed compared to before, there ought to be some clue in that for how we can insure that our children’s jaws are formed better. For more on possible implications for what we do now, see “A Modern World of Endemic Jaw Dysfunction.”