Italian researchers say that dogs' tail wagging sends a different message depending on the direction of the wag.
By examining dogs' interactions with people and other animals, the scientists found that a dog wags its tail to the right when it spots someone or something familiar and to the left when it feels threatened, The Daily Telegraph reported.
Giorgio Vallortigara of the University of Trieste and Angelo Quaranta and Marcello Siniscalchi of Bari University studied dogs with their owners, human strangers, cats and Belgian shepherd malinois, a large German shepherd-like dog that smaller dogs might find threatening.
The study suggests that in dogs, as in humans, the left side of the brain is involved in signaling to approach something while the right side advises retreat.
"Tail wagging is an important emotional response," Vallortigara said.
The study has been published in Current Biology.
Copyright 2007 by United Press International
Explore further: Who's top dog? New research sorts dominant and submissive canine poses