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Why Do We Have Wisdom Teeth?

x-ray image of erupting wisdom teeth

During our late teen years into our early twenties, the last of our permanent teeth begin to erupt. These teeth are our third molars, more commonly known as wisdom teeth. However, despite their name, they tend to be anything but wise, often coming in sideways or sometimes failing to erupt at all. Because of this, most wisdom teeth end up needing to be extracted or surgically removed from the gums. Having teeth erupt that are immediately removed raises the question of why we even have wisdom teeth to begin with.

Turns out, wisdom teeth are simply part of our evolutionary history. Thousands of years ago when our ancestors ate leaves, roots, nuts, and meats a third set of molars were essential to survival. This ancestral diet of course, rough food caused teeth to wear out faster and required more chewing power, thus a third set of molars was an evolutionary necessity. The jaw was also broader than the modern jawbone to allow for a more powerful chewing capacity.

However, nowadays our diets have become much softer in addition to the introduction of tools for eating such as spoons, forks, and knives. Modern food preparation methods have also evolved as we now cut, dice, chop, steam, boil, and bake almost everything we ingest. We no longer have to rely on our teeth to tear apart or grind down food in the same way as our ancestors. As a result, there is no longer a biological need for our third molars. In short this means that wisdom teeth which were once essential structures, have become vestigial, or useless due to evolution.

Still, some people don’t ever develop wisdom teeth. This is rather uncommon, however has been found to occur more frequently in agricultural populations rather than hunter-gatherer populations. Over the past thousands of years, the human skull and jaw have significantly reduced in size. Because of this reduction in size, anthropologists believe this is the reason why certain individuals are born without wisdom teeth.

This reduced size in the human skull and jaw is the primary reason why wisdom teeth cause so many issues in modern times. Initially, the human skull and jaw was much larger when third molars were an essential part of dental anatomy. However with evolution, the human skull shrank and now there is simply not enough room for a third set of molars. This is why wisdom teeth can come in sideways, only partially emerge from the gum line, or fail to emerge altogether. In addition wisdom teeth can cause a range of dental issues including crowding, damaged or decayed teeth, gum irritation, infection, inflammation, and gum disease.

Even if wisdom teeth are able to fully erupt from the gums, they can cause problems. Wisdom teeth are so far in the back of the mouth that it is hard to keep them clean by properly brushing and flossing them daily. As a result, food can accumulate in tight spaces and plaque can develop, housing bacteria. These could eventually cause cavities and gum disease.