The Mystery of Crooked Teeth in Humans Unveiledwoman with crooked teeth

If you look at your dog or cat, you may notice that their teeth are probably perfectly straight. Think about it – how often have you ever seen an animal with crooked teeth? Not very often, right? So why is it that nearly every person you know deals with some sort of orthodontic issues, from crooked teeth to overcrowding, wisdom teeth impaction, cavities, teeth grinding and more?

In the fossil record, our ancient ancestors almost never had impacted wisdom teeth, gum disease, or many of the orthodontic issues we have today. So what is it with modern humans that makes our teeth so darn needy and complicated?

Teeth – A Biological Marvel 

The structure of our teeth is a marvel of biological innovation. Our teeth are designed to fit together just right to create a chewing surface for grinding in the middle and back of our mouths, and sharp teeth for tearing in the front. Think of how you eat a smoked turkey leg at the Georgia Renaissance Festival. You bite a chunk off with your front teeth (hopefully with lots of dramatic flair like you’re playing Henry VIII in a movie), then you grind it up by chewing on the back teeth. Humans are omnivores, so our teeth evolved to have both functions.

The problem is, our diets changed faster than our teeth 

Over the millions of years that humans evolved, our diets remained relatively the same: lots of plant matter, which takes quite a bit of chewing and grinding before swallowing, and some meat and fish. Our mouths, in turn, evolved to process those types of foods so that our stomachs could absorb the critical nutrients from them. As long as our diets stayed consistent, our teeth were great at doing their jobs.

Then, our diets changed. No longer were we chewing tough, fibrous plant matter all the time. With the advent of agriculture, our wide-ranging diets became more and more limited to what we could grow in our areas. Then we cooked it until it was soft and easy to eat. That was all great for feeding a population but bad for our oral health.


The oldest “toothbrush” on the historical record comes from about 3500 BC, when Babylonians chewed on sticks to clean their teeth. Before those days, we don’t have any record that humans cleaned their teeth, but we do have evidence that they had very low incidences of cavities and gum disease. How did they manage to keep their teeth healthy without brushing? Diet.

In ancient times, sugar was rare, as were acidic foods. Today, sugary diets and high-acid foods are wreaking havoc in our mouths by creating an environment for bacteria to flourish and cause cavities.

Our teeth evolved to handle a diet of all-natural, low-sugar foods, grains, and meat. Today’s modern diet, with its loads of sugar (especially here in America) and acidic foods, has pushed our teeth past their limits – and cavities are the result.

Crooked teeth 

Today, nine in 10 people have teeth that are somewhat misaligned, and 3/4 of humans don’t have enough space in their mouths for their wisdom teeth to emerge properly. This was not the case with our ancient ancestors.

Again, diet seems to be the culprit. The theory is that, back in our pre-historic days, chewing all that tough food put stress on human jaws that caused the jaw bone to grow bigger and stronger. You can still see this phenomenon, as doing weight-bearing exercises helps build stronger bones, because bones grow stronger in response to more stress.

Our modern diets, with their soft, cooked foods, do not put as much stress on our jaws as ancient diets, so our jawbones don’t grow as large. When our jaws aren’t as big, our teeth just don’t fit anymore. It’s like trying to put a house worth of furniture in a single room.

Want better oral health? Eat like our ancestors. 

A diet that is rich in natural, unprocessed foods and includes a lot of crunchy foods that give your jaw a workout can help you keep your teeth healthier now and in the future. Until then, Atlanta Orthodontic Specialists will be here to help you get the smile nature didn’t deliver, but we can!