Dogs wag their tail to convey a lot more than just happiness, study finds

A recent study suggests that dogs wag their tail not only to indicate happiness but also to communicate other complex emotions.

A team of European researchers proposed two major theories on the evolution of tail wagging in dogs in a recent study published in the journalBiology Letters.

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The study suggests that when dogs experience a positive emotion, they tend to wag their tail more towards the right. However, their wagging inclines towards the left more when they have a negative emotion.

The authors stated that wagging and arousal-related hormones or neurotransmitters might be linked in the dogs' bodies. They also mentioned that there might be a connection between the stress hormone cortisol and tail wagging.

Silvia Leonetti, the study's first author and research assistant in comparative bioacoustics at the Max Planck Institute for Psycholinguistics, told Newsweek, "Many animals have tails and use those tails for moving (an alligator swimming), balance ( a cat walking along a narrow fence), and removing pests (a horse swatting flies away from its body). But those examples contrast with domestic dogs, who use their tails primarily for communication rather than any other function."

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Dogs, compared to wolves, wag their tails more often and start from a very young age, suggesting that the behaviour evolved in the line after humans started domesticating them. Thus, dogs might have adapted wagging as a way to communicate with their human masters.

"One study found that during food denial situations, dogs wagged their tails more when a human was present versus not, suggesting that tail wagging may also function as a requesting signal," the authors said.

However, this evolution might not be deliberate. According to the study, wagging may have emerged as a by-product of another characteristic, like tameness or friendliness.

The authors bred a cohort of silver foxes for over 40 generations for the research. They found that the foxes showed a dog-like tail-wagging behaviour after being selected for traits like tamability and docility.

"Based on this, we hypothesise that the domestication process may have led to changes at the anatomical and behavioral level that altered tail wagging behavior in dogs," the authors said.

Although these theories suggest how and why tail wagging evolved, there are many unanswered questions. "We are just scratching the surface," Andrea Ravignani, the study's senior author, said.

It remains a mystery how dogs control their behaviour and how well they decipher the meaning of wagging among other dogs.

"We echo the concerns of other researchers that these procedures may impair the communicative repertoire of an animal (although this should be empirically tested by comparing breeds) and reduce how well a dog can express its feelings and communicate," Ravignani said.

(With inputs from agencies)