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Desert Diary


Who doesn't remember their mother telling them to chew their food? But why is it important? After all, reptiles and birds don't have to chew their food, so why should we? It's because we're warm-blooded, having to process much more food than reptiles, and because our distant ancestors evolved in a different direction than birds. For whatever reason, the reptilian line that led to us concentrated on processing food initially in the mouth, grinding it up so that the digestive juices had plenty of surface area for chemical processing, while birds delayed the processing to farther down the digestive tract.

As mammals perfected our chewing mechanisms, uppers and lowers had to come together quite exactly, and the reptilian habit of replacing teeth haphazardly throughout life no longer worked well. So, we're stuck with only two generations of teeth: the baby teeth, sized for the small jaw of the young, and adult teeth to last through the rest of life. Of course, it doesn't always work out that way, which is the origin of the expletive, Dadgumit!
pen and ink

Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.