Dogs evolved muscles that give them 'sad eyes' to trigger a nurturing response in their owners

Dogs have evolved muscles around their eyes to look cute to humans, scientific research has shown for the first time. The muscles allow dogs to raise a quizzical eyebrow and to look sad - giving them facial expressions similar to our own. The authors say that the eyebrow raising movement triggers a nurturing response in humans. They makes the dogs' eyes appear larger and more child-like. The authors say that the eyebrow raising movement triggers a nurturing response in humans.