Why Do Dogs Wag Their Tails? Scientists Examine the Endearing Behavior (2024)
For pet parents, perhaps nothing is more heartwarming than coming home to a dog excitedly wagging its tail in greeting.
But, for all the daily tail-wagging that goes on in homes around the world, scientists still don’t understand exactly why dogs do it. In a new paper published Wednesday in the journal Biology Letters, researchers outline a few theories. They hope other scientists will take up the mantle and test these hypotheses to shed more light on this endearing habit of man’s best friend.
“People think wagging tail equals happy dog,” says Emily Bray, a canine cognition expert at the University of Arizona who was not involved with the new research, to Science News’ Jude Coleman. “But it’s actually a lot more complicated than that.”
One possible explanation, known as the “domestication syndrome” hypothesis, relates to the human domestication of dogs, which began as early as 35,000 years ago. Perhaps tail-wagging was a behavior that humans unintentionally selected for, because it was linked with other preferable traits, like tameness or friendliness toward people. Tail-wagging may have simply been a byproduct of other specifically targeted characteristics.
Another theory, called the “domesticated rhythmic wagging” hypothesis, suggests that humans consciously or unconsciously selected for tail-wagging during domestication, because they are drawn to rhythmic stimuli.
Of course, these are just theories—and not everyone agrees with them. Holly Root-Gutteridge, an animal cognition researcher at the University of Lincoln in England, tells the Guardian’s Nicola Davis the rhythm hypothesis is an “interesting thought,” but adds that she’s skeptical about how much humans are really responding to the rhythmic beats of a dog’s tail.
More broadly, the new paper adds to the big-picture understanding of what scientists do and don’t know about tail-wagging. The authors reviewed more than 100 studies about the behavior and summarized their findings.
For example, past research has shown that dogs primarily wag their tails to communicate, which stands in contrast to how other animals use their tails. Some, like whales, use the appendage for swimming, while others, like horses, use them to keep away flies. Kangaroos use their tails like a powerful fifth limb to help propel themselves forward.
Dogs also seem to wag their tails in different ways to convey different messages. For instance, scientists believe wagging more to the right means a dog is curious and wants to approach, while wagging to the left is correlated with uncertainty. Low tail wagging—where dogs pin their tails down against their back legs—is also linked with insecurity and submission.
“Perhaps the coolest thing is that dogs can perceive those asymmetries in other dogs,” study co-author Taylor Hersh, a bioacousticianat Oregon State University, says to Science’s Sara Reardon. “There’s a really neat study where they showed dogs video silhouettes of a dog either wagging to the left side of its body or to the right. They found that they responded differently [with dogs acting more anxious when the silhouette dog was wagging to the left].”
The researchers also identify gaps in the scientific literature. A big one: How much are dogs consciously controlling their tails, and how much of their wagging is unconscious? Past research also indicates that dogs tend to wag more than their other canine relatives, like wolves—but, again, scientists don’t know why.
Moving forward, they suggest researchers study tail-wagging in a more systematic way, such as by analyzing videos. They suggest exposing dogs to a variety of stimuli and taking measurements to see if any patterns emerge in their heart rates or hormone levels while wagging their tails. In addition, they propose more studies that involve neuroimaging techniques to study the animals’ brains during this behavior.
Learning more about tail-wagging may have animal welfare implications, reports Newsweek’s Pandora Dewan—for example, does docking a dog’s tail affect its ability to communicate? But it could also help us learn more about ourselves. Since humans domesticated dogs, any evolutionary insights into a ubiquitous behavior like tail wagging could reveal more about early humans, too.
“By looking at how dogs are today, we get to travel back in time and see what the human domestication process has done in terms of dog behavior,” says study co-author Andrea Ravignani, a comparative bioacoustics researcher at the Max Planck Institute for Psycholinguistics, to Science. “So modern dog behavior, to some extent, brings a fingerprint of early humans.”
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Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.
may have simply been a byproduct of other specifically targeted characteristics. Another theory, called the “domesticated rhythmic wagging” hypothesis, suggests that humans consciously or unconsciously selected for tail-wagging during domestication, because they are drawn to rhythmic stimuli.
Is it only because they are happy? It turns out that the answer is complex. Tail-wagging is “clearly a communication mechanism,” says animal behaviorist Nicholas Dodman, a professor emeritus at Tufts University and head of the Center for Canine Behavior Studies.
But a pup wagging their tail does not always mean they are happy. In fact, a wagging tail may indicate anxiety, fear, or insecurity. In this post, we will examine a dog's primary physical cue, the tail wag, and look at the difference between happiness and anxiety.
Tail wagging is frequently associated with both positive and negative arousal, suggesting a correlation with arousal-related hormones and neurotransmitters [24–32]. For example, there is indirect evidence linking oxytocin and tail wagging, especially when dogs are reunited with a familiar human [33,34].
Some, like whales, use the appendage for swimming, while others, like horses, use them to keep away flies. Kangaroos use their tails like a powerful fifth limb to help propel themselves forward. Dogs also seem to wag their tails in different ways to convey different messages.
Since tail movements are controlled by skeletal muscle and tail wagging is a learned behavior, the action is likely intentional. However, it's possible that tail movements may be a combination of voluntary and involuntary (or at least “autopilot”) control.
Licking is a natural and instinctive behaviour to dogs. For them it's a way of grooming, bonding, and expressing themselves. Your dog may lick you to say they love you, to get your attention, to help soothe themselves if they're stressed, to show empathy or because you taste good to them!
As well as expressing love, a dog's stare can sometimes indicate that they are not happy. It's unlikely that your dog will give you this sort of assertive stare, but it may be reserved for other dogs that they feel threatened by. It's usually accompanied by a stiff upright body and a stillness.
When kissing a human, dogs are communicating that they are friendly and non-threatening. Puppies continue this behavior of licking faces with humans who typically react with attention, affection, and play.
Especially if you tell them often, they will come to recognize your words and tone and will understand the love you have for them. As long as you're showing your dog love and affection, they will understand it. However, if you want to throw in an extra belly rub or treat once in a while, they will love you for it!
One of the biggest misconceptions about dogs is that a wagging tail means the dog is friendly. While it certainly can mean this, there are a multitude of reasons dogs wag their tails. At the most basic level, a wagging tail simply means the dog is responding to something in their environment.
When a dog suddenly stops wagging his tail and freezes, it may mean that he wants divert a threat without being aggressive. Many dogs do this when petted by strangers, to communicate that they don't want to interact with them.
The way your dog wags his tail may mean more than you think.
Scientists have discovered that the direction of a tail wag can indicate a dog's mood. A tail wagging more to the right (from the dog's perspective) indicates a relaxed, happy dog, while a tail wagging more to the left indicates an anxious or nervous dog.
The phrase originates in the saying "a dog is smarter than its tail, but if the tail were smarter, then it would wag the dog." The concept has strong intersections with many other aspects of Diversionary foreign policy, particularly the rally 'round the flag effect, as wag the dog actions tend to both distract and seek ...
Wagging Tails: One of the most obvious signs that your dog loves you is a wagging tail. A wagging tail usually means that your dog is happy to see you and is excited to be near you. The more enthusiastic the wag, the happier your dog is to see you. Licks: Dogs show affection by licking their owners.
The dog's tail was originally designed to assist the dog in his balance. Variables such as how high the dog carries his tail, how quickly the dog is moving his tail, and even whether the tail is being wagged more to the left or right side of the body can convey a lot of information.
A tail wagging in circles almost always signals that the dog is very excited and happy. A tail wagging mostly to the left signals unhappiness and other negative emotions, while a tail wagging mostly to the right signals happiness and other positive emotions.
Excitement is another emotion your pup can experience during their sleep, which can lead to quite excessive tail wagging. Your pup may also start loudly yapping or barking during their dreams and even get up and walk about! Quite often, with excitement, your dog will even look like they're smiling - how cute!
“This uses oxygen, but if the tail wags too much, and the muscles work really hard, the cells start to respire anaerobically, without oxygen. This generates less energy, and a by-product called lactic acid which causes temporary muscle fatigue and soreness.
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