Kaminski said that there was compelling evidence that dogs developed a small muscle that intensely lifted their internal eyebrows after being domesticated by the wolf.
"The results suggest that expressive eyebrows in dogs could be the result of the unconscious preferences of humans that influenced selection during domestication," Kaminski said in a statement. "When dogs make the move, it seems to arouse a strong desire to heal them in humans."
Dogs that move more eyebrows would have "an advantage in terms of selection over others and strengthen the trait" eyes of puppy "for future generations.
She added that the movement of the eyebrows could also give people "the illusion of human communication".
In earlier research, Kaminski found that dogs moved their brows more when humans looked at them than when they did not look at them. In this study, she and her coauthors suggested that it was proven that dog facial expressions "are not merely demonstrations of inflexible and unintentional emotional states, but rather potentially active attempts to communicate with them." other".
The muscles of the faces of dogs and wolves are similar except above the eyes. The muscle that allows dogs to raise eyebrows is "a rare and irregular cluster of fibers" among wolves, researchers said in a statement on Monday.
"The raised inner eyebrow movement in dogs is driven by a muscle that does not systematically exist in their closest living relative, the wolf. This is a striking difference for the separated species only 33,000 years ago and we believe that remarkably fast facial muscle changes can be directly related to the increased social interaction of dogs with humans, "he said. said Anne Burrows, a professor at Duquesne University, said in the statement.
Rui Diogo, professor and professor at Howard University, is also a co-author: "I must confess that I was surprised to see the results myself because macroscopic muscle anatomy is usually very slow to evolve, and this happened very quickly. indeed, in a few tens of thousands of years.
The researchers noted that it is also possible that humans prefer individuals who show white in their eyes and that the muscle exposes more the white part of the dog's eyes.
The researchers said: One species of dog did not have muscle, it is the Siberian husky, which is one of the oldest breeds. (Just in case Snowflake is looking at you right now.)