What is a primary function of the eyebrows?

The primary function of the eyebrows is to direct moisture away from the eyes, which is crucial for maintaining clear vision and eye health. When it rains or during high levels of perspiration, eyebrows help to channel water away from the eye area, preventing it from running into the eyes and causing irritation. This protective feature allows for better visibility and comfort.

In contrast, while eyebrows do play a role in enhancing facial expressions, their primary biological function relates more to physical protection than emotional signaling. Filtering light into the eyes is primarily accomplished by the eyelids and the structure of the eye itself, not the eyebrows. The support provided to the eyelids is minimal, as eyebrows do not have a structural role in supporting eye anatomy. Therefore, their most significant function remains in moisture management, safeguarding the eyes from various environmental factors.