Sadness comes with a set of identifiable marks where the eyebrows are drawn upwards in the middle and curve down toward the end. There is also a slight vertical furrow between the eyes. Taken together, this is called Darwin’s grief muscle. The mouth points downward similarly, with the outside corners of the mouth pointing downward.

When we are angry, we often press our lips together so hard that the upper lip almost disappears. The eyes may widen acsross the upper eyelids, which the lower eyelids are contracted. The inner corners of the eyebrows pull downward, and there is often enough pressure there to create a furrowed brow.

In fear, a scared person’s eyebrows may be close to horizontal, and wrinkles in evidence across the forehead. Similar to anger, people who are frightened may open the upper eyelid more widely and show more of the whites of their eyes, while the corners of their mouths pull the lips into a horizontal line.

Happiness is generally accompanied by rising cheeks, and we describe the accompanying smile as going up to someone’s eyes when the muscles around the eyes tighten (hence the way that smile lines lead to permanent lines around the eyes). Authentic smiles, also called a Duchenne smile, were first described by French neurologist Guillaume Benjamin Amand Duchenne de Boulogne. They are characterized by those eye wrinkles, whereas a phony or forced smile is missing those characteristic smile lines.

Raised upper eyelids, in addition to exposing additional whites of the eye, often accompany surprise. The mouth or jaw may also open as a part of the response.

Is anyone rolling their eyes at you? This gesture is quite common in expressions of contempt, in addition to the left corner of the lip being pulled out asymmetrically, creating a dimple.

People who are feeling disgusted may wrinkle their nose as they might to a bad smell, and/or generate wrinkles at the top of the nose between their eyes. The upper lip may also be raised.