Dogs communicate with each other using their tails, and new research is helping to decipher what each tail wag means.
The direction of the tail wag - left or right - turns out to be very important, according to a study in the latest Current Biology.
While all wags look about the same to a glancing human, dogs are really clued into their direction and the hidden meaning behind that.
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When canines are distressed, such as when they see an unfriendly dog, they tend to wag their tails to the left.
This all occurs because the tail wagging is reflecting what's happening in the dogs' brains, according to lead author Giorgio Vallortigara, a researcher at the University of Trento's Center for Mind/Brain Sciences, and his colleagues.
They found that left-brain activation produces a wag to the right, and right-brain activation produces a wag to the left.
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"The direction of tail wagging does in fact matter, and it matters in a way that matches hemispheric activation," Vallortigara said in a press release.