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.

Smiles do more than express emotion - new research shows they can unconsciously influence trust and shape how we perceive ...

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 ...

African wild dogs might use facial expressions to communicate with each other as they hunt in packs on the savanna. Arno Meintjes via Flickr under CC BY-NC-SA 2.0 DEED Puppy-dog eyes are irresistible.

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 ...