[Reading Science] Dogs' Tails and Bodies Move Independently

Max Planck Institute in Germany
"Tail Does Not Affect Body Movement"
"Seems to Be a Means of Communication and Pest Control"

[Asia Economy Reporter Kim Bong-su] What purpose do dogs use their tails for? Some animals like lizards use their tails importantly during movement to maintain balance, and cows use them to repel pests. However, a study has found that dogs' tails are unrelated to movement and seem to be used solely as signals to communicate with companions and humans.

According to the British newspaper The Guardian on the 3rd, the Animal Movement Research Team at the Max Planck Institute in Germany published these research findings on the preprint server 'bioRxiv' on the 30th of last month.

Despite decades of research, scientists had not definitively understood the role of dogs' tails. It was unclear whether, like lizards, cats, or monkeys, dogs use their tails to maintain balance during movement, as a means of signaling to companions, or to repel flying insects like flies.

The research team created a mathematical model to observe what happens when a dog twists or turns its torso, moves its legs and tail, or jumps, aiming to resolve these questions. They focused especially on how much the tail's movement affects the torso's sway or trajectory when the dog jumps into the air. However, observations confirmed that the tail's movement had almost no effect.

Lizards maintain balance with their tails when falling from trees. Cats rely on their tails when landing on the ground. Monkeys use their tails to maintain balance while moving through trees. Unlike these animals that rely on their tails for agile movement, dogs' tails do not play an important role. This phenomenon was similar across all dog breeds. The research team stated, "We confirmed that dogs' tails have no effect on complex movements such as jumping," adding, "All breeds are similar, suggesting that dogs' tails are not used for locomotion but rather for other purposes such as communication or pest repelling."

Meanwhile, previous studies have found that dogs communicate with companions and humans through their tails. They use them to express emotions such as dominance, friendliness, and fear. For example, a tail held high indicates confidence or a desire to play, a stiff tail signals threat or anxiety, a tail tucked between the legs means fear, and a gently wagging tail side to side is known as a sign of friendliness.