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Desert Diary
Biology/007 Fish


Many a man wishes that he could turn from a Mr. Milquetoast into a suave Agent 007 in the blink of an eye. As ridiculous as that might sound, we now know that might not be impossible. In groups of a species of cichlid fish, one male is dominant, shows bright colors, is aggressive, and is the only male to mate. Meek subordinate males know their place. When the dominant male is removed, though, it only takes a few minutes for some of the subordinates to begin to change color and become more aggressive.

Study of what's going on in the fish brain reveals that this social clue—the disappearance of the dominant male—results in a sudden increase in activity of a gene in the brain. In fact, the substance produced by the gene more than doubles in the newly dominant fish. Now people aren't fish, but this finding strongly suggests that social clues could easily turn on or off human genes affecting behavior. Don't you bet every 90-pound wimp is wondering now just where that switch is?
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 production of KTEP, National Public Radio for the Southwest at the University of Texas at El Paso.



Holden, C., ed. 2005. Big fish. Science 310:616.

Web Resources

Introduction to Cichlids