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Wagging Dogs

July 9, 2009

A listener asks: Why do dogs wag their tails?


Why dogs wag their tails. I’m Bob Hirshon and this is Science Update.

Listener Kiera Richardson of St. George, Utah asks why dogs wag their tails when they’re happy. Well, tail movements help dogs keep their balance, and wagging may have evolved from this as a form of communication. According to University of California, Davis behavioral scientist Benjamin Hart, recent research suggests that dogs tend to wag their tails to the right when they see their owners approach, but to the left when they see a threatening dog. This makes sense, because movements on the right side of the body are controlled by the left side of the brain, which in primates is associated with positive moods. Conversely…

BENJAMIN HART (University of California, Davis):
The right brain expresses negative emotions, and gives the muscles of the tail a left-sided bias.

This suggests that dogs do in fact wag their tails, to the right at least, when they’re happy. I’m Bob Hirshon, for AAAS, the science society.