Why is your hair gray and eyebrows black?

It is a common misconception that all people have gray hair and black eyebrows. Hair color, including the color of hair on the head and eyebrows, is determined by several factors, primarily genetics. Genes control the production of melanin, a pigment that gives color to hair, skin, and eyes. Two main types of melanin determine hair color: eumelanin (brown or black) and pheomelanin (red or yellow).

As people age, the production of melanin decreases, leading to a reduction in hair color. This process is known as graying or canities. The rate at which hair turns gray varies among individuals and is influenced by both genetic and environmental factors.

It is possible for someone to have gray hair on their head while still having black eyebrows due to variations in the distribution of melanin-producing cells in different areas of the body. Additionally, some people may experience uneven graying, where certain hair follicles stop producing melanin while others continue to do so, resulting in a mix of gray and colored hair.

It is also worth noting that hair color can be affected by external factors such as sun exposure, chemical treatments, and certain medical conditions. These factors can contribute to hair color changes, including the development of gray hair.

Therefore, the differences in hair and eyebrow color between individuals can be attributed to genetics, varying rates of melanin production, and the influence of external factors.