Human Teeth and Evolution

Patient at dentist with open mouth during treatment on teeth
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Much like Charles Darwin found out about the beaks of finches, different types of teeth have an evolutionary history as well. Darwin found that the birds’ beaks were specially shaped depending on the type of food they ate. Short, sturdy beaks belonged to finches who needed to crack nuts to get nutrition, while long and pointy beaks were used to poke into the cracks of trees to find juicy insects to eat. 

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Human Teeth and Evolution

Whitened teeth after dental procedure
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Teeth have a similar evolutionary explanation and the type and placement of our teeth are not by accident, but instead, they are a result of the most favorable adaptation of the diet of a modern human.

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at the dentist choose white of teeth and finish prothesis
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Incisors are the four front teeth on the top jaw (the maxilla) and the four teeth directly below them on the lower jaw (the mandible). These teeth are thin and relatively flat compared to the other teeth. They are also sharp and strong. The purpose of the incisors is to tear flesh from animals. Any animal that eats meat would use these front teeth to bite off a piece of meat and bring it into the mouth for further processing by other teeth.

It is believed that not all human ancestors had incisors. These teeth evolved in humans as the ancestors transitioned from getting energy mostly from gathering and eating plants to hunting and eating the meat of other animals. Humans, however, are not carnivores, but omnivores. That is why not all of the human teeth are incisors only.

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Perfect teeth
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The canine teeth are comprised of the pointy tooth on either side of the incisors on both the top jaw and the bottom jaw. Canines are used to hold flesh or meat steady while the incisors rip into it. Shaped in a nail or peg-like structure, they are ideal for keeping things from shifting as the human bites into it. 

The length of the canines in the human lineage differed depending on the time period and the main food source for that particular species. The sharpness of the canines also evolved as the types of food changed.

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Closeup x-ray image of teeth and mouth
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Bicuspids, or the pre-molars, are short and flat teeth found on both the top and bottom jaw next to the canines. While some mechanical processing of food is done at this location, most modern humans just use the bicuspids as a way to pass food back farther to the back of the mouth.

Bicuspids are still somewhat sharp and may have been the only teeth in the back of the jaw for some of the early human ancestors that ate mostly meat. Once the incisors were finished tearing the meat, it would get passed back to the bicuspids where more chewing would occur before being swallowed.

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Child having a dental examination
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In the back of the human mouth is a set of teeth that are known as the molars. Molars are very flat and wide with large grinding surfaces. They are held in very tightly by the roots and are permanent from the time they erupt instead of being lost like milk teeth or baby teeth. These strong teeth in the back of the mouth are used thoroughly chew and grind up food, especially plant materials that have a strong cell wall around every cell.

The molars are found at the back of the mouth as a final destination for the mechanical processing of food. Most modern humans do the majority of their chewing on the molars. Because they are where most food is chewed, modern humans are more likely to get cavities in their molars than any of the other teeth since the food spends more time on them than the other teeth nearer the front of the mouth.

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Scoville, Heather. "Human Teeth and Evolution." ThoughtCo, Aug. 27, 2020, Scoville, Heather. (2020, August 27). Human Teeth and Evolution. Retrieved from Scoville, Heather. "Human Teeth and Evolution." ThoughtCo. (accessed March 30, 2023).