09/16/2026
Around a campfire, far from anywhere familiar, a family that has clearly had a hard few days is still laughing, and something about it looks different from an ordinary polite smile. The eyes are doing something a mouth alone cannot fake.
French neurologist Guillaume Duchenne studied this distinction in the 1800s, and researcher Paul Ekman later built on that work in the 20th century, identifying what is now called the Duchenne smile, a genuine smile that engages both the muscles around the mouth and the orbicularis oculi muscles around the eyes, producing the crinkling often called crow's feet. A polite or social smile, sometimes called a non-Duchenne smile, typically only involves the mouth, because most people cannot consciously control the eye muscles involved in a genuine one.
This is part of why a posed photo can feel subtly off even when everyone is technically smiling, and why a candid photo of real laughter can feel so much warmer even if it is less composed. The eyes tend to tell the truth even when the rest of the face has learned to perform. π₯
Can you usually tell the difference between someone's real smile and their polite one, and what is it that actually gives it away for you?