Written by Raymond Nakamura
Once upon a time (before the Internet), Raymond earned his doctorate studying the hydrodynamics of sand dollars. Nowadays he rents his brain at raymondsbrain.com for writing, cartooning, and thinking, when he is not washing the dishes, walking the dog, or helping his daughter with homework. Follow him on Twitter @raymondsbrain.

Created date

Tuesday, February 15, 2011 - 10:59am

Why do we have baby teeth?

My six-year-old daughter's first tooth came out last month and others are now wiggly. Lately, she been after me to help get them out, but I've been forbidden by my more prudent half from applying any Rube Goldbergish contraptions to speed up the removal of our daughter's wigglies. Still, this got me wondering about the point of baby or deciduous or milk teeth.

Starter Set

Humans have twenty baby teeth and thirty-two permanent teeth. Your own toothage may vary. Most mammals also have two sets of teeth. Dogs and cats, for example, get their baby teeth in a few weeks and then lose them in a few months (I don't know what that is in dog or cat years).

Seen One, Seen Them All

Most other vertebrates, i.e., fishes and reptiles, have teeth that come and go on an incoming and ongoing basis. This is a boon to all those tropical trinket tourist traps that sell necklaces with shark teeth. A given fish or reptile has a set of teeth that are pretty much all the same.

All About the Fit

Mammals, however, usually have different kinds of specialized teeth that need to fit together properly to work well. The arrangement follows a species specific dental formula. Seems the jaws of the young are too small to accommodate all the permanent ones. The permanent ones are keepers because they probably require a lot of energy to produce. The exceptions seem to prove the rule.

Teeth and Consequences

Baleen whales have baleen instead of teeth. Yet they have tooth buds as embryos, even though they do not form into teeth. Dolphins and other toothed whales have teeth that are all the same and only have one set of teeth.

Hard Wear

Some mammals are particularly hard on their teeth. Elephants, for example, chew lots of tough plant material. They go through six sets of molars. If an African elephant lives longer than its last set of molars, it may die of starvation. I suspect they probably die of other causes first. But I wear a night guard anyway.

Teeth that Never End

Rodents handle the problem of wearing down teeth with continually growing ones. Beavers, for example, have self sharpening incisors for gnawing down trees. The babies (called kits) are born with chompers from the get go.

Handling the Tooth

Then you have the human parents who are pulling out their kids' baby teeth early. I don't know if the tooth fairy is involved, but apparently if the teeth still have the blood supply, they are a source of stem cells, which can be a potential salvation against diseases when they are older. It kind of creeps me out. What about you?


I am still not getting the

I am still not getting the answer to the question. Nothing explained why humans have baby teeth? Was it because our adult teeth take longer to grow, was that the conclusion to this article that spent a better time explaining other mammal's teeth?

Yes, (assuming from the

Yes, (assuming from the article) adult teeth take more energy to make. Also, there isn't enough room for all of the 32 adult teeth in a child's mouth. Infants need smaller and less teeth so they can begin to eat on their own and start to talk. Going from personal experience, baby teeth can also serve as permanent adult teeth if a person doesn't have that adult tooth. I hope I explained this well enough. Have a good day.

I agree with Ashley above.

I agree with Ashley above. You went on a rant on animal teeth which leaves nothing but more questions to my research.

Pretty sure that it was

Pretty sure that it was explained that the human jaw is not big enough at birth to accommodate full size teeth?

"Seems the jaws of the young

"Seems the jaws of the young are too small to accommodate all the permanent ones." (We count as mammals.)

It was explained perfectly.

It was explained perfectly. The human jaw is too small to accommodate adult teeth. Since it requires a lot of energy to produce these adult teeth, a temporary set, 'baby teeth', come in. I loved all the other animal teeth facts. Thank you!

Actually, it wasn't explained

Actually, it wasn't explained perfectly - since baby teeth "come in", our adult teeth could theoretically just arrive in the order that our mouth grows/expands. A much better job of explaining the reasoning seems to be here: (Paul) - URL was blocked by spam filter but check search for "freysmiles" and "why-do-we-have-baby-teeth". Jaw size at birth and acting as guides for adult teeth seem to be more in line with the real reason we need baby teeth...

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