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Are wisdom teeth vestigial structures?
Question Date: 2002-07-09
Answer 1:

Hi Seekers of toothy Wisdom-

The story I have always heard about why we call them wisdom teeth is that one gets them about the time one starts becoming wise.

Most people get their first set of molars when they're about 6, their second set at about 12, and the "wisdom teeth" at about 19. Only one of my wisdom teeth ever showed up. I was about 25 then. The rest of my wisdom teeth never "erupted." This is fairly common. Some people get all of their wisdom teeth and they work perfectly. Other people have one or more that get "impacted" or blocked. Impacted teeth can cause problems. Some people's wisdom teeth never form or never try to erupt. (By the way, I'm 37 and I still have a "baby tooth." It's one of my canine teeth)

This is a X-ray picture of wisdom teeth. I got it from the Internet.

The wisdom teeth are the four at the farthest corners. The one on the lower right is actually sideways. Can you find her fillings? Are they vestigial? That's a great question!

Vestigial structures are basically evolutionary "leftovers" like our appendix or a whale's thigh bone. They don't really have a function, but they were important to our distant ancestors. Our ancestors and the modern apes have wisdom teeth. You might call wisdom teeth vestigial in that they aren't very useful now, and can even cause problems. But as I mentioned, some people have them and they work fine. So this is sort of a gray area. Sometimes they are functional and sometimes they're not. The world has a lot of things that don't fit neatly into our categories. If our mouths continue to get smaller, wisdom teeth may be truly vestigial some day.

I was curious about when our jaws began to get too small for our wisdom teeth. This is a question for a physical anthropologist. An anthropologist said that the human jaw is smaller now than it was just 300 years ago, because we chew less. The bones we use more get more developed. But this would not be an evolutionary change. In evolutionary change, the genes change. If we went back to a diet that required a lot of chewing, we'd have big jaws too.

How do you think our diet has changed in the past 100 years? How about 20,000 years ago, before agriculture? How about before humans used fire to cook? Do you think changes in our lifespan and diet have made dentists necessary? How different is diet in different populations around the world?

Answer 2:

That is a good question and I don't think I can give you a clear answer. Wisdom teeth used to serve a useful purpose, but are now considered by many scientists as vestigial organs. A vestige is a degenerative or imperfectly formed organ or structure having little or no utility, but in the earlier stage of development of a species performed a useful function. The reasons that wisdom teeth are now "outdated" are many.

Until quite recently, our diet included mostly very coarse food, as well as impurities such as dirt and sand. This coarseness would abrade teeth so significantly that they would take up less space in the jaw. Permanent teeth were also frequently lost at an early age, which would create more space in the jaw. Because the diet was so coarse and hard to chew, the jaw itself would develop into a larger bone because of this constant workout. All of these factors would create more space for the wisdom teeth when they came in.

The heavily processed diet of today does not produce the tooth abrasion or jaw development that we used to see. Modern dentistry has pretty much eliminated significant loss of permanent teeth at an early age. This leaves us with too many teeth and not enough jaw. The wisdom teeth still develop as they always have, but they have nowhere to go. When this happens, the teeth are considered "impacted," meaning that they are not in normal position and function. Quite often they can not be cleaned properly which results in tooth decay, gum decease and infections. These are some of the reasons why we have them extracted.

Thanks for asking your question.

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