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Study explores the mystery of why dogs wag their tails

In a fascinating exploration of the bond between humans and dogs, scientists from the Max Planck Institute for Psycholinguistics have delved into the reasons behind dogs’ distinctive tail wagging behavior. The relationship between humans and dogs, a bond that dates back to the dawn of civilization, has always included the enigmatic aspect of why dogs wag their tails more than other canines.

Human preferences

The researchers, in an opinion piece in Biology Letters, propose a theory linking human enjoyment of rhythmic movements to the evolution of dogs’ tail wagging behavior. They suggest that early humans might have unconsciously preferred dogs that exhibited more rhythmic movements. 

However, they acknowledge that this is just one theory and that the behavior could also be a byproduct of dogs becoming more sociable.

Tail wagging behavior 

Despite the mutual enjoyment derived from tail wagging, there’s been limited research into its evolutionary origins. Unlike domesticated dogs, undomesticated canines like wolves wag their tails less frequently and primarily for communication. 

The researchers point out that tail wagging in dogs seems innate rather than learned, as evidenced by the behavior of wolf and dog pups raised by humans, with dog pups beginning to wag their tails much more frequently as early as three weeks old.

Domesticated rhythmic wagging 

The scientists propose two theories. The first, termed “domesticated rhythmic wagging,” suggests that humans may have selectively bred dogs for more frequent and rhythmic tail wagging. 

“Humans have remarkable abilities to perceive and produce rhythmic sequences, particularly isochronous patterns where events are evenly spaced in time,” the authors wrote. The preference for rhythmic stimuli, ingrained in human cognitive neuroscience and linked to pleasurable responses and reward system engagement, could have influenced this selection.

Domestication syndrome hypothesis 

The second theory, known as the “domestication syndrome” hypothesis, posits that tail wagging could be an incidental result of breeding for friendliness. This idea is supported by a study on silver foxes selectively bred for tameness, which showed that friendlier foxes in later generations exhibited more dog-like tail wagging, even though this trait wasn’t specifically selected for.

The researchers also discuss the variation in tail wagging behavior across different dog breeds, noting that selection may not have been uniform; for instance, hunting-type dogs wag their tails more than shepherd-type dogs.

Ultimately, the scientists acknowledge that further experiments are necessary to conclusively determine the true reason behind dogs’ tail-wagging behavior. Their insights provide a thought-provoking look at how human preferences and evolutionary processes might have shaped one of our closest animal companions’ most endearing traits.

More about tail wagging 

Tail wagging in dogs is a form of canine communication that can express a variety of emotions and intentions. Contrary to popular belief, tail wagging doesn’t always mean a dog is happy. The nature of the tail wag can convey different messages.


The speed of the wag is significant. A rapid wag is generally a sign of excitement or happiness. If a dog wags its tail slowly, it might be unsure or assessing a situation. 


The height at which a dog holds its tail while wagging can also be telling. A high tail often indicates confidence or aggression, while a lower tail might signify fear, submission, or anxiety.


The direction of the tail wag also plays a role. Recent studies suggest that a tail wagging more to the right might be associated with positive feelings, while a left-biased wag could indicate negative emotions.

Body language 

It’s important to consider the whole body language of the dog, not just the tail. Other cues like ear position, posture, and facial expression provide context to the meaning of a tail wag. 

For instance, a wagging tail combined with relaxed body language and a playful stance often means the dog is happy and inviting interaction. Conversely, a wagging tail with stiff body posture or bared teeth could signal aggression.

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