When a dog wags their tail at you, it’s adorable. Still, have you ever wondered why dogs have this extra appendage? You don’t see humans walking around with tails, so why did evolution decide to bless our canine friends with them?
The truth is that a dog’s tail serves a number of purposes, including movement, balance, and communication. Explore these elements below as we discover how the tail aids a dog in day-to-day life and why they’re so important.
What is a Dog’s Tail Made Of?
Put simply, a dog’s tail is an extension of the backbone; it comprises interlocking, flexible bones, wrapped in muscle, and covered in skin. Dogs use their muscles to lift, lower, curl, and wag it. In addition, an abundance of nerves and blood vessels helps the tail work effectively.
Dogs can fully control the movement of their own tail, but some movements could be subconscious expressions – much like how we use our eyebrows.
Tails come in a wide range of varieties to suit each dog; for example, the tails of the Shiba Inu and Siberian Husky are especially furry; this means that when the dogs are out in the cold, they can wrap their tails around the nose and face to stay warm.
Movement
For many centuries after humans first domesticated dogs, we bred them to carry out some sort of job or task for us. One of the reasons why dogs are such helpful companions to us is their speed and agility, and if you watch a dog at work (or play), you’ll see how their tail helps them to move so efficiently.
Sometimes, a dog needs to change direction while running at speed. Throw a toy and watch them chase it; you’ll see that when they want to change direction, their front legs turn, but their back legs keep going in the original direction.
To balance this and counter the weight of the rear end of the body, a dog’s tail turns in the direction they wish to run. This helps them to maintain good balance and ensures they don’t stumble or spin off course.
Balance
A dog’s tail works as a balancing tool, not only when working but also when engaging in other activities. If you watch a dog walk along a narrow surface, you’ll see that the tail works to counterbalance the weight of the dog’s tilt. This is similar to how a tightrope walker uses a balance bar to keep them steady.
It is a particularly useful skill for dogs who love to explore the great outdoors; it helps them climb various surfaces and keep balance when on uneven footing, e.g., rocky surfaces or those filled with tree roots.
The tail also helps a dog to jump and swim. When a dog jumps, they throw their tail into the air to help with trajectory; this helps to ensure that the dog maintains balance and lands on its feet. When swimming, the tail acts like a rudder helping them to “steer” in the right direction and make sharp turns without losing their balance.
Communication
It shouldn’t surprise you too much that dogs use their tails for communication; after all, we each recognize the sign of a happy dog when their tail is wagging. Still, their tail conveys far more messages than we are often aware of.
For example, a wagging tail doesn’t always mean a dog is happy. A tail wag can be the equivalent of a greeting or nod of recognition, or it could be a sign that they’re feeling anxious. A study published in Current Biology suggests that a tail wagging on the right side of the body is more relaxed, while a tail wagging on the left side is more likely to indicate a stressed or alert dog.
In addition, when your dog wags their tail, the muscles around the anal glands contract, allowing your dog to spread their unique scent. You might notice that dominant dogs keep their tails higher than submissive dogs. This is because the former wants to let everyone know they’re present, while the latter is happy to go unnoticed.
We know that dogs use their tails for communication as it is a learned behavior; puppies will not begin to wag their tails until they are between 30 and 50 days old. At this age, the littermates begin to play with one another and start to learn how to communicate.
Why Don’t Humans Have Tails?
If tails are such a great aid to communication, balance, and movement, why don’t humans have one? Well, the answer is we did, but it disappeared over time. But not entirely. What you might not know is that humans do have a tail for the first eight weeks of embryo development, but a process called apoptosis means we lose it long before we’re born.
The reason we don’t have a tail is that we don’t need one. Over millions of years, our ancestors developed their skills and abilities to a point where we no longer needed a tail. A genetic defect could lead a human to be born with a tail, but the chances are very slim.
