Eyebrow hair differs from head hair in several respects. The hair on a person’s eyebrows will not grow as long as head hair. It is also thicker, coarser, and differently shaped than the hair on an individual’s head. The roots of eyebrow hair are thicker, and the hair there does not fall out as quickly as head hair.
All human hair is made of intertwined strands of a type of protein called keratin. Still, hair has different characteristics depending upon where it is located. Hair on one part of the body can appear quite different than hair on another part. The differences between eyebrow hair and head hair provide a clear example of this.
Hair grows from a small bubble in the surface of the skin called a follicle. The base of each strand of hair nestled within a follicle is called the hair root. Attached to the follicles are sacs called sebaceous glands. These glands secrete a type of oil that gives hair its shiny appearance. Each hair is covered by a clear outer layer called a cuticle that can either make it smooth or coarse, depending upon the nature of its surface. Hair constantly grows, matures, and is then shed by the body to be replaced.
The hair on a person’s head has small roots. The hairs themselves are thin and narrow to a point at the ends. All the hairs on a person’s head are nearly the same thickness and can grow up to 40 inches (about 100 cm) or even longer. Head hair can be straight, wavy, or curly. A fully mature strand of head hair generally lasts up to three months before it is shed by the body.
The roots of a person’s eyebrow hair are slightly thicker than head hair. Each hair contains more strands of keratin and, unlike head hair, can vary slightly in diameter. Eyebrow hairs grow to a much shorter length than head hair, with the maximum length reaching only about 0.5 inches (approximately 1 cm). The hairs of the eyebrow are also coarser than head hair and have a curved shape, even if the head hair is straight. These hairs, once mature, generally stay in place up to nine months before being shed, and in most instances, even though a person may lose all of his or her head hair, eyebrow hair might thin out but generally will not be completely lost.
Eyebrow hair also grows at a different angle from the body than head hair. Head hair basically grows out from the skin at a gentle slope, but eyebrow hair grows at a much sharper angle. With regard to the color, although the hairs of the eyebrow often match the color of the hairs on a person’s head, this is not always the case. The hair above the eye can be a different shade lighter or darker than head hair. As a person ages, eyebrow hair takes longer to turn gray or white than head hair, and sometimes, it never turns color at all.