Although some studies suggest possibilities, we’re not entirely certain what causes TMJ. It’s most likely the result of injury, diet, and genetic factors, and some have even suggested that it’s something modern people are more prone to, which would make sense if it were related to routine crowding, which is much more common among modern people.

However, it turns out that primitive people suffered from TMJ much more than moderns, pointing to a quirky explanation of why we develop this condition.

TMJ in Neolithic Populations

Based on skeletal remains, neolithic people got TMJ at least as much as moderns, and likely much more. Although about 10% of modern people develop TMJ, in this population¬†perhaps two thirds of people (67%) had TMJ. We don’t know what kind of TMJ symptoms they suffered, but we do know they had bony lesions on the jaw joint, typical of late-stage TMJ, which is even rarer in modern populations.

Why did so many prehistoric people get TMJ? It’s likely due to all the raw and unprocessed food they ate. A diet full of rough food, including tough, fibrous plants, gamey meat, and even stone particles from the grinding tools they used for grain caused them to wear their teeth down much faster than ours, and put high stress on their jaw joints. These people also tended to use their jaw as a “third hand,” using their teeth as tools, a bad habit that can contribute to TMJ.

But it’s worse than that. It turns out our jaws are just poorly adapted for chewing rough and unprocessed food, even though this is what most of our primate ancestors ate. Our jaw joint is placed in a poor location compared to the chewing plane, making it harder for us to bring force to bear on the teeth.

Did Cooking Cause the Change in Our Jaws?

But why would our jaws be poorly adapted to eating our food? Perhaps cooking is to blame. How and what we eat can influence the shape of our jaw. For example, people developed an overbite after eating off a fork became popular, and we know that cooking likely changed the shape of our jaw, leading to impacted wisdom teeth.

The only problem with this is that humans started cooking about two million years ago, giving us ample time to adapt to our altered diet by 4000 BC. And although people started farming at about this time, farming didn’t actually change our diet or dental problems. And studies show that from the neolithic period to the medieval period, diet had little impact on the shape of the jaw.

If these problems aren’t to blame, what is causing our jaw to be poorly adapted to so many of the tasks it is asked to perform daily?

Your Jaw’s Real Purpose

The best explanation is that our jaw’s development has been driven by another purpose than eating. Before cooking, people spent about 50% of their time eating, but once they started cooking, softer food meant they only had to spend about 5% of their time eating, which meant that most of the time their jaw was being used for something other than eating–namely speaking–and speech became the primary influence on the jaw’s shape.

When speech influenced the shape of the jaw, we ended up with a jaw that was unsuited for hours and hours spent chewing hard, unprocessed food. Some have said that sleep apnea is the result of anatomical changes related to speech, and we know that TMJ and sleep apnea can be influenced by some of the same anatomical features.

And as a result of these changes, humans began to develop TMJ. Although our diet of soft, processed foods means that it’s less common for us, once it develops it can be disabling.

If you suffer from TMJ, you can blame the gift of speech, and be thankful that there are many TMJ treatment options available. To learn how treatment can help your TMJ in Denver, please call (303) 691-0267 for an appointment with a TMJ dentist at the TMJ Therapy & Sleep Center of Colorado.