A new study has found that facial musculature between domestic dogs and gray wolves differs only around the eye. The study reports that exaggerated eyebrow facial movements in dogs cause their eyes to “appear larger, giving the face a more paedomorphic, infant-like appearance, and also resembles a movement that humans produce when they are sad.” This potentially elicits a “caregiving response from humans, giving individuals that inherit the trait a selection advantage with humans.” The researchers conclude that “the data suggest that selection—perhaps mainly unconscious—during social interactions can create selection pressures on the facial muscle anatomy in dogs strong enough for additional muscles to evolve.” Read study