Wednesday, December 25, 2013

Teeth and forks



In a past article, I mentioned how the story of bones truly started with teeth. Here's another story about teeth.

If you check your teeth, chances are that when you clench them, the upper row of teeth covers the lower row and your upper incisors end up in front or the lower ones. This is the case for the vast majority of humans today and is referred to as an overbite. The reason I was interested in this subject is because I was born with a genetically-caused underbite aka. mandibular prognathism of which I've been operated since.

But overbite appeared in humans only about 250 years ago all over the world. As archaeologists have found with ancient skulls, up until 250 years ago, upper and lower incisors reached exactly on top of each other. No row of teeth was in front of the other. Also, because the change happened so suddenly and so widely all over the world, the explanation is not likely to have genetic origins.

So what did change? Forks! The usage of forks for eating became common in Europe and in the Americas about 250 years ago. And that's the time when the morphology of teeth started changing. In other places like China, the usage of chopsticks for eating is more ancient and also coherent with the change of teeth. What is more, there were period when eating utensils were reserved for privileged classes of society while the rest were still eating with their hands. And that is reflected by different teeth on the bones of dead people from different social classes.

The explanation it seems, is that eating with our hands increased the usage of incisors and eroded our upper incisors. Nowadays, our incisors are less solicited and the upper ones simply outgrow the bottom ones.

You can find references to this subject in this article of The Atlantic and that mention of QI since this appeared in a recent episode of the British tongue-in-cheek trivia show.


Conclusion

What is surprising with this subject is how something seemingly mundane like using a fork modifies the shape of our body.

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