If a dog has eyes that seem to tell you something or demand your attention, this could be a way for evolution to manipulate your feelings.
The researchers found that dogs had developed muscles around their eyes, which allowed them to make expressions particularly appealing to humans.
A small facial muscle allows the eyes of a dog to mimic an "infant-like" expression, which causes a "nurturing response".
According to the study, such "puppy eyes" have helped domesticated dogs to bond with humans.
Previous studies have shown just how much such dog expressions could appeal to humans, but this study done in the UK and the US shows that an anatomical change around the dog's eyes has been made possible.
& # 39; Expressive eyebrows & # 39;
This allows dogs to create what researchers call "expressive eyebrows" and "create the illusion of human communication".
"When dogs get into the movement, it seems like humans are very eager to take charge of them," says the study, co-authored by Dr. Juliane Kaminski of the University of Portsmouth.
This muscular movement allows dogs' eyes to "look bigger, more like an infant's and also look like a movement that humans produce when they're sad."
She says humans would have an "unconscious preference" to protect and breed dogs with such an attractive trait, which would give them an evolutionary advantage and reinforce this change in subsequent generations.
"The evidence is convincing that dogs have developed a muscle to lift the inner eyebrow after being domesticated from wolves," says Dr. Kaminski, in a study published in the Proceedings of the National Academy of Sciences of the United States.
The findings of British and American researchers in anatomy and comparative psychology show that face change has developed over thousands of years of dogs living alongside humans.
Previous research has shown that dogs are more likely to use this phrase "puppy eyes" when a human looks at them – suggesting that it's a problem. deliberate behavior and intended for human consumption.
Professor Anne Burrows of Duquesne University, USA, co-author of the report, explains that in terms of evolution, changes to the dogs' facial muscles have been "remarkably fast" and could be "directly related to the increased social interaction of dogs with humans".
According to Professor Bridget Waller of the University of Portsmouth, the results show "how much faces can be important to capture our attention and how powerful face expression can be in social interactions".