The history of our teeth is an ancient and fascinating story. If in the past, the robust jaws of our ancestors gave way to well-ordered teeth, the phenomenon of crooked teeth (or malocclusion) has become surprisingly common in our modern societies, reports National Geographic magazine. It would not simply be a question of genetics: our diet, our lifestyle and even the evolution of our morphology would be involved.
There was a time when human teeth were naturally straight. The first Homo sapiens possessed a strong and broad jaw, perfectly adapted to chewing raw, tough or fibrous foods: roots, nuts, dried meat, etc. This demanding diet intensely used the jaw muscles, helping to shape a robust face, cut for function more than for aesthetics.
Around 12,000 years ago, the invention of agriculture radically changed the way we eat… and chew. Unlike raw foods hunted or gathered in the wild, grains, cultivated fruits, and processed products were much more tender. No more intense chewing work. Our facial muscles relaxed and our jaws, less used, began to shrink.
According to Myra Laird, an expert in dental science at the University of Pennsylvania, this transformation is both an evolutionary adaptation – the body building only what it needs – and a direct consequence of our softer diet. Less chewing, less muscle, less bone surface: the jaw has literally been shaped over generations.
Too many teeth, not enough room
And there, the problem: evolution did not think to align the size of our teeth with that of our reduced jaw. Result? Teeth that lack space, crowd together or grow crooked.
Julie Lawrence, an assistant professor of biological anthropology at the University of Nevada, compares our dental structure to the way a zipper works. For the teeth to erupt properly, the jaw must move forward and give them space. In modern jaws, which are too narrow, this natural process is often compromised, especially for the famous wisdom teeth, which are often condemned to remain blocked or extracted.
One explanation among others
If our jaws shrink because of our diet, that doesn’t explain everything. Cases of malocclusion have been discovered in some ancient hominids, although these observations should be taken with caution – well-preserved fossil skulls are rare and teeth in good condition are even rarer. Other factors can come into play such as genetics, developmental anomalies or even the environment.
Certain populations are also naturally more prone to crooked teeth and certain anomalies (such as overgnathism or severe underbites) seem more linked to our genes than to our diet.
Susan Herring, an orthodontic researcher at the University of Washington, says: “Today we are much more sensitive to aesthetic concerns. It’s not necessarily that people have more malocclusions, but simply that we pay more attention to them.”
The perfect smile is not as natural as you think. It is the result of a slow transformation, influenced by our diet, our modern lifestyle and our aesthetic criteria. So, the next time you chew gum or admire a perfectly aligned smile, think about this long evolutionary journey… and about your ancestors who knew nothing about dental braces.
