Similarly, the findings show that this facial change has developed over thousands of years of dogs living alongside humans. Examining dog history and evolution closely, the experts are confident that expressive movements are deliberate (as in, intended for human consumption).
Lead anatomist Professor Anne Burrows, at Duquesne University, Pittsburgh, USA, another of the study’s co-authors, says: “To determine whether this eyebrow movement is a result of evolution, we compared the facial anatomy and behaviour of these two species and found the muscle that allows for the eyebrow raise in dogs was, in wolves, a scant, irregular cluster of fibres.
“The raised inner eyebrow movement in dogs is driven by a muscle which doesn’t consistently exist in their closest living relative, the wolf.
“This is a striking difference for species separated only 33,000 years ago and we think that the remarkably fast facial muscular changes can be directly linked to dogs’ enhanced social interaction with humans.”
A spokesperson for the university further elaborates that the only dog species in the study that did not have the muscle needed for creating such expressive movements is the Siberian husky, among the more ancient dog breeds.