How Dogs' Tail Wags Speak Volumes (to Dogs)

Wagging tails are little more complicated than you might think. A new study finds that dogs are able to pick up on friend or foe depending on whether a tail is wagging to the left or right, reports the BBC. Research from a few years back suggested that a dog wagged to its right when it was happy and friendly and to the left when it sensed danger. The new research, which involved measuring heart rates and such, shows that dogs themselves are able to pick up on the differences.

"It is very well known in humans that the left and right side of the brain are differently involved in stimuli that invokes positive or negative emotions," says the lead Italian researcher. "Here we attempted to look at it in other species." One part that's a wee bit disappointing: He doesn't think the dogs are intentionally communicating with each other, reports National Geographic. But they have apparently learned how to process the visual cue over eons. "It's just fascinating," a Duke researcher not involved with the study tells AP. (More discoveries stories.)