Eyebrow

An eyebrow is a pair of short hairs located on the face, positioned above each eye. They sit at the junction where the hair-bearing skin of the forehead (the area above each eye) begins, and consist of hair that is shorter and coarser than that on the head.

Eyebrows have two functions: a physical one and a communicative one. Physically, the hairs shed sweat and rainwater away from the eyes so they do not run directly into them. Communicatively, eyebrow movement forms an important part of facial expression, conveying surprise, concern, or doubt.

Structure

Eyebrow hairs grow from follicles in the skin. Like all hair, they are composed of a protein called keratin. Eyebrow hairs have a shorter growth cycle than scalp hair; this is why eyebrows typically remain at a fixed length and do not continue growing. Their color depends on melanin and is usually darker than the scalp hair of the same person.

Several facial muscles move the eyebrows. One lifts them upward, while others pull them down or draw them together, creating a furrow between them.

Eyebrows and facial expression

Behavioral and psychological researchers regard eyebrows as part of the system for expressing emotion. Raising both eyebrows is usually associated with surprise or greeting; lowering them toward the center is associated with concentration or anger. Eyebrows also aid in face recognition: images with eyebrows altered have been found to be harder to recognize.

Culture and aesthetics

Many societies, including Somali society, have traditions of grooming or enhancing eyebrows—through plucking, threading, or the application of cosmetics. The styles chosen vary by era and region. Eyebrows are also referenced in proverbs and poetry, often as a marker of facial beauty.

Health conditions

Eyebrow hair can be lost for various reasons, including diseases affecting hair follicles, hormonal disorders, or certain medications. There are medical approaches to growing new hair. Such conditions require specialist evaluation.