Why do we have eyebrows?

Eyebrows serve a practical purpose: their arched shape channels sweat, rain, and debris away from the eyes to the sides of the face, keeping vision clear. They are also central to non-verbal communication, letting us signal surprise, anger, doubt, and countless other emotions with tiny movements. Research suggests expressive eyebrows may have given early humans a social advantage over heavy-browed relatives. They even help us recognise faces — people are surprisingly hard to identify without them.