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Desert Diary
Biology/Bad Smells


What's that horrible smell? Ick—something dead! Why do things smell bad; why doesn't a sewer smell like rose blossoms, or a least like something that doesn't make your stomach turn over? The likely answer, as so often is the case, is natural selection. Remember, it's our brains that assign pleasure or distaste to a smell, which is why dog brains don't treat odors the same way as ours. Mostly, things that smell bad to us are things that would harm us if we ate them; way back when, individuals who found such odors attractive didn't live to pass on their genes.

It's also possible that we're seeing the results of coevolution—two groups having a major impact on the evolution of each other. The bad smells of rotting material are mostly the product of bacteria, and many of these bacteria don't survive well in the digestive juices of animals. Those bacteria that smelled especially bad were those that lived, as was true for animals with brains that interpreted those smells as horrible; evolution working for survival of both!
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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.