The Evolution of Teeth: Where Did They Come From and How Have They Changed?

Dentists: the villain in every children's movie, everyone's least favorite doctor to visit and tik-tok's latest obsession. Most consider anyone who devotes their life to looking at and touching other people's teeth strange, but in dentists' defense, teeth are actually fascinating! Did you know that enamel (the shiny coating on your teeth that you can see) is the toughest part of your body? Or that no two people have the same tooth structure? 

Similar to a fingerprint, your "tooth prints" are so specific to you that they are often used in forensic studies to identify bodies! For the same reason, teeth are also valuable tools for evolutionary scientists. They are easy to characterize because they are highly specialized, and the enamel make them sturdy and long-lasting fossils. So, how did these enamel-coated nuggets of history come to be?

Well, teeth emerged shortly after jaw-bearing organisms called gnathostomes emerged from earlier jawless fish. It is unclear whether they evolved jaws for predation, mastication or protection, but whatever the cause, teeth-bearing gnathostomes were more evolutionarily successful than any other organism, which is why teeth are present (in some form) in all vertebrates.

 Image showing the skulls of different vertebrates, including humans

Teeth are variable in number, size and shape across species because of environmental pressures. This includes diet, a major catalyst for modern day human dentition. Our primitive ancestors had a diet that revolved around plants, raw meat, nuts and tree roots. You heard that right, tree roots. Therefore, they needed strong molars and canines to cut through their food. Those with the most teeth and the strongest teeth were able to have the broadest diet, and so they survived and reproduced more often. This is where our wisdom teeth come from.

Image showing wisdom teeth coming in behind molars

Wisdom teeth are essentially back-up teeth, in case early humans wore out all their others. They are now considered vestigial, and most people have to have them removed. Vestigial structures are leftovers from our ancestors that we no longer need, but have not been removed from our gene pool. Wisdom teeth are erratic in growth and often hit against other teeth when they grow in, which is why they cause pain and need to be removed.

Early humans had much larger jaws than we do now, because they needed an immense amount of force to chew. Modern inventions of utensils and cooked food have caused our jaws to shrink, causing a phenomenon known as- you guessed it- “crowded mouth.” This is often corrected with orthodontics or tooth extractions. The opposite is also possible, as some people have hypodontia, which means they are born without several of their adult teeth. This is again because our jaws are shrinking and we do not need as many teeth as our ancestors did. Smaller jaws and cooked food have also resulted in more and more babies born without wisdom teeth, sparing them from the painful removal process and disorienting recovery period.  

Image showing the comparison of an early and modern human skull

Modern teeth are also smaller and closer together, and are coated in a thicker layer of enamel. Our canines have shrunk and dulled dramatically as well, in response to soft, cooked food.

In the future, you can expect to see babies with smaller faces, jaws and teeth, and more and more cases of hypodontia and “crowded mouth.” We have made our environment extremely favorable to us, so we no longer need the large, strong and widely spaced teeth present in early humans. But just because we are evolving to have fewer and smaller teeth doesn’t mean we shouldn’t take care of the ones we’ve got! Make sure to brush and floss twice a day, and see your dentist regularly for cleanings!