Why Do Dogs Need a Tail? |
Most dogs, except in the cases where humans have intervened, have a tail. Many of these tails, like those on a Golden Retriever or an Irish Setter, are quite handsome and pleasing to the human eye, but one must ask the question, “Other than simply being an elegant ornament, does a dog’s tail have any meaningful function?”
Careful kinematic research, such as that done by a Japanese team headed by Naomi Wada, has determined that the dog’s tail was designed to assist the dog with balance. When a dog is running and turns quickly, he throws the front part of his body in the direction he wants to go. This causes his back to bend; however, the forward velocity is such that his hindquarters will tend to continue in the original direction. The momentum can result in the dog’s rear swinging wide, which may slow his rate of movement or even cause the dog to topple over as he tries to make a high-speed turn. The dog’s tail helps to prevent this problem. Moving his tail in the same direction that his body is turning serves as a counterweight, which reduces the tendency to spin off course.
When moving at lower speeds, dogs also use their tails to assist them when walking along narrow or unstable surfaces. By swinging the tail to one side or the other (in the direction opposite to any tilt in his body) the dog helps to maintain his balance. This is much the same way that the circus tight rope performer uses his balance bar. However, the tail is not particularly important on flat surfaces at normal speeds. Then it becomes available for other uses, and evolution has seized upon the opportunity to utilize the tail for communication........