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Desert Diary


Chemists have formulas for just about anything imaginable, but not tooth formulas. Those are for scientists who study mammals, and are simply shorthand ways to communicate how many and what types of teeth a species of mammal has. For example, humans have 32 teeth divided into incisors, canines, premolars (bicuspids to a dentist), and molars. A mammalogist would take just one side of the jaws and say something like I2/2, C1/1, P2/2, and M3/3, which translates to two upper and lower incisors, one upper and lower canine, two upper and lower premolars, and three upper and lower molars. Multiply by two and you have the 32 teeth nicely delineated.

Different kinds of mammals may have different tooth formulas, evolutionarily reduced in most kinds from the ancestral formula of I3/3, C1/1, P4/4, and M3/3 for a total of 44 teeth. Little Red Riding Hood wasn't too far off when she commented on "Grandma's" teeth, because wolves have retained 42 of the 44 primitive set.
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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.