Understanding the wagging tail of our dogs
All dog-lovers know the happy feeling of seeing their dog approach with a bouncing step and a wagging tail! No matter how long you were gone, your dog always greets you with exuberance and joy when you come home. And we are taught that a dog wagging his tail means that he is friendly.
Tail wagging may be one of the most conspicuous of all animal behaviors
Dogs are common anywhere there are humans, and it is estimated that one billion share the planet with us. Given the close relationship between dogs and people, it is not surprising that we have developed many ways to communicate. Humans are especially attuned to the movements of the dog’s tail.
What is the science behind that swishing dog tail? You might be surprised to learn that we know little about this very common behavior. The authors of a recent evaluation of canine tail wagging published in Biology Letters commented that canine tail wagging may well be one of the most conspicuous of all animal behaviors for humans to observe.
In this post, I’ll review some of the interesting findings about this most common behavior.
Did you know this about canine tail wagging?
Animals use their tails for many reasons
Tails are used for many purposes. For animals like monkeys and cats, the tail helps with balance when running and jumping. Sometimes the tail is most useful for swatting flies – think of horses or elephants. Likely the most interesting are tail movements used in communication. If you pay attention to a cat’s tail, for example, you will learn a lot about what she wants or feels. Many birds use their tails during courtship displays. Dogs use their tails to communicate more than any other canid (dog relatives like wolves or foxes).
Wagging is asymmetric in dogs
Dogs don’t wag their tails in the same way all the time. They move their tails more to the right when they feel more positive, like seeing their pet parent. Wagging with a left bias is usually associated with withdrawal. This can happen when seeing an unfamiliar person or dog, or during aggressive interactions. While you may not have noticed this subtle difference, dogs understand the meaning of a right- or left-side bias when interacting with other dogs.
Tail wagging conveys information
Tail wagging and “tail carriage” (or the height of the tail when wagged) conveys information in response to dogs, humans, and even objects. These two factors indicate submission and subordination during interactions between dogs. For example, low tail carriage often signifies submission rather than aggression. Dogs wag their tails the most with their pet parent.
The evolution of dog tail wagging
Dogs start to wag their tails earlier and significantly more than wolves, their closest relative. How did tail wagging develop in dogs? Scientists believe it was during the process of domestication. The trait could have been specifically selected. Dogs that wagged their tails the most could have been prized by humans, perhaps due to our attention to rhythmic stimuli.
An alternative explanation could be that other traits were selected for, such as friendliness, and tail wagging happened to increase as well. Support for this idea comes from studies in fox domestication, in which selection for tameness resulted in other traits appearing (including tail wagging, floppy ears, and different color patterns).
Finally, the self-domestication hypothesis may have been important. The idea is that wolves that were naturally less afraid and more friendly to humans had advantages (like being fed). Over time, their natural behavior changed to benefit from a closer relationship with humans. Perhaps wolves that wagged their tails more were rewarded with food and protection, leading to more tail waggin’ pups being born.
The authors of the study emphasized the need for more study of this common, yet poorly understood, canine behavior. In the meantime, take a moment to think about your own pet and how his or her tail is telling you something. You might be surprised at what you learn.