Give Now

A Moment of Science

Evolution in Your Mouth

Have you ever doubted or questioned the teachings of Evolution? If you want to learn more, all you have to do is look inside your mouth and find answers.

A baby girl smiling

Photo: AHMED... (Flickr)

A baby girl smiling and showing how her mouth evolves as she grows.

Say the word “evolution”and some folks think of dusty archaeologists examining bone fragments.

However, while evidence of previous life forms does play a central part in our understanding of evolution, it isn’t necessary to go on a dig to see it in action; you might just look inside your mouth.

We all learn in our younger years that human beings have thirty-two teeth. They aren’t all the same, though. The pointy incisors in the front are easily distinguished from the flatter, double-edged bicuspids that run along the side. Different looking teeth also serve different functions. Those incisors are great for biting and holding on, while the bicuspids do more of a saw-motion for chewing.

Now here’s something you may not know. Strictly speaking, it isn’t true that everyone has thirty-two teeth. Even excluding people with dental problems, some folks have only thirty, or even twenty-eight. The ones that are missing are often the farthest back in the mouth. Where did they go?

One likely answer is found in evolution. Ten thousand years ago human beings ate much more raw meat. With a rough diet, you need lots of grinding teeth to help prepare your food for digestion. Later, with the gradual advent of cooked foods, not all those teeth were needed anymore. If someone is born without them, she or he doesn’t suffer any ill consequence; a scientist would say there’s no evolutionary pressure to keep those teeth.

The result? Many thousand years later, some of us don’t have as many grinding teeth as others. The dimensions of the human mouth, the jaw, and the skull are evolving, right underneath your nose.

  • Pingback: The Evolution And Science Behind Wisdom Teeth | A Moment of Science - Indiana Public Media

  • 伊翔 鄭

    Hi, dear Mister, 

    My name is Archer Cheng and I have a question after I read ” the pointy incisors in the front are easily distinguished from the flatter, double-edged bicuspids that run along the side…” in the paragraph. I am not sure that incisors are pointy; that might be cuspids?

  • Bruce Herdrich

    This mouth evolution argument is unscientific, unless an exhaustive search of fossil dental records throughout all of human history is made. The argument only has merit if the complete search shows that the percentage of the earliest human mouths with 32 teeth is much higher than today’s percentage, while the percentage of today’s humans with 28 teeth is much higher than that for the earliest humans.

    How do you know that the 28 tooth and 32 tooth percentages are not the same from both eras? You really need to do some research for any wisdom on this. (Wisdom Teeth). Even then that hardly proves mouth evolution. 32 teeth or 28 teeth, they are still 100% mouth, no doubt about it!!! Think about it seriously.

  • Bruce Herdrich

    No one has ever seen a mutation mindlessly attach a “proto-mouth” to an animal whose parents had none, nor ever seen the environment thoughtlessly shape such a “proto-mouth” throughout subsequent generations into a complete mouth, with lips, gums, teeth, tongue and an articulating jaw.

    The very first Galapagos Finch seen by humans, had a mouth (beak and tongue) identical to the mouths of many of today’s Galapagos Finches. Over the intermediate generations, some of these Finches’ beaks merely varied back and forth in their size and shape within a limited range.

Stay Connected

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from A Moment of Science:

Support for Indiana Public Media Comes From

About A Moment of Science

Search A Moment of Science