Every dog owner knows how hard it can be to say no to "puppy-dog eyes," but a new study shines light on how canine facial expressions evolved and why humans are able to understand them so well.

In social situations, humans often copy the facial expressions of others who they are interacting with. This phenomenon, ...

New preliminary data offers insight into why we may find dogs to be so darn lovable. A study found that dogs generally have faster facial muscles than wolves—muscles that allow them to quickly react ...

The muscles that allow for the "puppy-dog eyes" in domestic dogs is undeveloped in wolves, suggesting that the adorable look evolved to captivate humans. (Pictured: The author's dog, Smoky.) Courtesy ...

Facial expressions of emotion—such as the joyful smile you might display when encountering a friend or your angry frown when being cut off in traffic—are powerful social signals that are able to evoke ...