The sudden appearance of red hairs within a goatee or beard can be surprising, especially for individuals who do not have red hair on their scalp. This localized color change is a common biological occurrence rooted in the mechanisms that govern hair pigmentation across different parts of the body. Hair color is not always uniform because the genetic instructions for hair follicles are not always expressed identically.
The Genetics Behind Red Hair
Hair color is determined by melanin, a pigment produced by specialized cells called melanocytes within the hair follicle. Two primary types of melanin combine to create the full spectrum of human hair color. Eumelanin provides the darker pigments, such as brown and black, while pheomelanin is responsible for the lighter, reddish-yellow hues.
The proportion of these two pigments is controlled largely by the Melanocortin 1 Receptor (MC1R) gene. When the MC1R protein is fully functional, it signals the melanocytes to produce the dark pigment eumelanin, resulting in colors from dark brown to black.
Certain variants of the MC1R gene are mutated or less functional. When the receptor is deactivated, melanocytes primarily produce the reddish-yellow pheomelanin instead of eumelanin. To have red hair all over the body, a person typically needs to inherit two copies of a mutated MC1R gene, as it is generally a recessive trait.
Many individuals who do not have red hair may still carry one recessive copy of the mutated MC1R gene. This single copy is often enough to allow for the localized production of pheomelanin in certain hair populations. This genetic predisposition means that the underlying machinery to produce red pigment is present, even if the head hair is dark.
Differential Hair Pigmentation
The red pigment appears specifically in a goatee or beard, but not on the scalp, due to the independent nature of hair follicles in different body regions. Hair follicles are not synchronized across the entire body; each one operates with its own set of instructions. The follicles that produce facial hair are genetically distinct from those on the scalp.
Facial hair growth is significantly influenced by male hormones, or androgens, such as dihydrotestosterone. These hormonal signals interact with the hair follicles and can affect how the MC1R gene is expressed locally. The expression of the mutated MC1R gene can be more pronounced in the facial hair follicles compared to the scalp follicles.
This localized gene expression allows melanocytes in the goatee area to produce an excess of pheomelanin, even when scalp follicles maintain a dark color. Therefore, a man with brown scalp hair can have a reddish beard because the genetic instruction to favor red pigment is carried out only by the facial follicular population. This results in a mosaic of colors, where a single beard contains black, brown, and red hues.
Environmental and External Factors
While genetics provides the blueprint, external factors can also cause existing hair to appear redder over time. The most common external influence is exposure to ultraviolet (UV) light from the sun, which naturally degrades melanin within the hair shaft.
UV light breaks down the dark pigment eumelanin much faster than it breaks down pheomelanin. As the darker pigment fades, the underlying red tones of pheomelanin become more visible, causing the hair to take on a reddish tint. This effect is often more noticeable in facial hair because it is frequently exposed to the sun.
Certain topical products can also contribute to a reddish appearance by interacting with the hair’s structure and pigment. Hard water, which contains high levels of minerals, can build up on hair, potentially altering the color. Additionally, as hair loses pigment with age and turns gray, the loss of eumelanin can temporarily reveal a reddish-yellow hue before the hair becomes completely white.