Human vs Animal Sets of Teeth
Name: John D.
Date: Saturday, June 01, 2002
Is there a good reason, or guess, why humans have only two sets of teeth
(baby and adult) while other animals constantly replace them?
As with most questions of "why" things are the way they are in nature, we
usually can only guess. Evolution and adaptation have selected for traits
that succeed over many generations. Specifically, most mammals have teeth
similar to those of humans, with the exception of the incisors (front
gnawing teeth) of rodents like beaver, that continue to grow through their
lifetimes. Those teeth are not replaced by adults that lose them, though.
Some creatures, like sharks and some snakes, replace teeth throughout their
lives. Why? We can see that it is a successful survival strategy but how
they evolved is hard to say.
It is generally agreed that the reason humans have two (or three in some cases) sets of teeth deals with growth of the skeleton. Teeth are essential for eating many foods and the early set of teeth are too small as we grow or evolve into adulthood. The jaw grows larger and we drop the smaller teeth for large ones; and more of them too for our jaws are larger. Early humuns did not have the luxury of soft foods so babies need to grow teeth for eating after been weaned.
The reason why other animals have other methods of replacing teeth reflects their diet and environmental needs. Humans are omnivores, but many herbivores grind their food continuously and need to replacement constantly. Animals that use their teeth for more than eating such as rodents, have incisors that grow continuously. These animals need to constantly grind their front teeth down, but this normally takes place with their day-to-day activites consisting not only of eating, but building nests and opening hard shelled food, etc.
Now there are other information about teeth that you can look up easily.
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Update: June 2012