The beard (from the Latin word barba, itself derived from an Indo-European word bharda) is the set of hair covering the cheeks, chin, jaw as well as the outside of the lips (upper and lower) of the ‘man.

The beard hair consists of a part buried under the skin, the hair follicle Usually called the root of the hair, and of a visible part, the stem or hair fiber formed of three concentric layers, the cuticle, the cortex and the medulla.

The hair is rooted about 4 mm below the skin. It is formed within a cavity, the hair follicle, by an assembly of two types of cells (keratinocytes and melanocytes) which multiply very rapidly by successive divisions.

The keratinocytes harden to form the hair shaft and then die. The hair bulb contains one melanocyte for about thirty keratinocytes. Melanocytes transmit melanin (the pigment responsible for hair color) to keratinocytes: the hair shaft therefore grows pigmented until the melanocytes disappear with age.

Le life cycle of each hair is divided into three phases, the anagen phase (youth), the catagen phase (old age) then the telogen phase (death). The duration of this hair cycle is not synchronized and varies depending on the areas in humans (6 to 7 months for the mustache and upper lip, 15 months for the chin, 2 to 6 years for the hair). Cycle after cycle, the connective tissue sheath of the hair follicle hardens and shrinks (a phenomenon of miniaturization of the hair follicle), which slows down the anagen phase of the hair which lasts shorter and becomes thinner, gradually forming a down or alopecia.

Facial hair, sexual dimorphism.

Homo sapiens is sexually dimorphic in a number of traits, including overall hair distribution (1). Compared to women, men wear more facial hair due to a higher level of androgen hormones.

What is the beard for?

It is often claimed that the beard is the remnant of our distant past as a prehistoric man, when he was covered with hair to be protected from the cold. In reality, nothing is less certain. Recent research indicates that it could equally constitute the reappearance of a trait originally lost by the species. Glabreté is in fact particularly widespread: from China to Japan (with a few exceptions), from Alaska to South America (among populations preceding European colonization) and in Africa (the entire Sahelian strip from east to west as well as the south of the continent). Facial hair could be the result of sexual selection: the beard is sometimes attractive and sometimes repulsive depending on the cultures (2).

Spread of disease. A study has shown that healthcare professionals with beards do not carry more pathogens than healthcare professionals who do not3.

Sunburn protection. A study has shown that the beard can provide some protection against sunburn. The longer the hairs, the greater this protection would be (the UPF can range from 2 to 20). However, the protection decreases as the solar zenith angle increases (4).

Kerion (ringworm). Kerion is one form of ringworm. It appears as a rounded, thick and firm cupboard, with a crusty surface, dotted with follicular orifices from which pus and blood come out. In adults, it is mainly found on the beard (5).

Sycosis. Beard sycosis is a skin condition characterized by chronic infection of the chin and its surroundings. The irritation is caused by a deep infection of the hair follicles, often with Staphylococcus or Propionibacterium6 bacteria.

Women with beards (hirsutism). Hirsutism is an excessive development of the hair system in women, particularly in the face, caused by too high a level of androgens. It is most often acquired, although congenital forms are possible, and is associated with an excess of male hormones in women. The patients present with acne, deep voice, irregular periods or amenorrhea, beard growth and virilization.

Ingrown hair. Ingrown hair is hair that has come out of its follicle and has not pierced the dermis. It will therefore grow inside the skin and create skin complications, the most serious of which are skin inflammation, the rise of pus, scars and redness.

Hair cutting and hardening. It is believed that the more you cut a hair, the more it grows back and hardens. However, the hair being a dead dander, cutting it has no impact on its cycle. On the other hand, pulling it out stimulates its follicle and promotes the growth of a more powerful hair.

Effect of Minoxidil on beard growth. No scientific study has shown that minoxidil can accelerate the growth of the facial hair system although several testimonies argue for its relative effectiveness. Its ability to widen blood vessels and open potassium channels could explain such an action. However, it is recommended that you discuss this with your doctor before considering such treatment, as there are many side effects.

Influence of lack of sleep and sexuality. One study found that a sleep deficit reduced beard growth due to decreased protein synthesis (8). Conversely, one study showed that beard growth in men was significantly faster during periods of sexual activity (9).

Toxicological analysis. Beard hair has been suggested as an alternative source for drug detection when scalp hair is not available.

Beard hair transplant. For people who want to benefit from hair restorative surgery and have a limited donor area, it is possible to use facial hair to increase potential follicular supply (10).

Erotic role-playing system. Body hair has long been associated by humoral theories with “blood temperament”, and ideally masculine. In the context of these theories, the hair is erected as a marker of sexual potency (11). The differentiation of hairiness would thus be a major sign in the system of erotic “role” prevalent in our societies (12).

Beard perception. According to a study, women are more attracted to men with light beards, while a full beard inspires confidence and the ability to be a good father (13). The nature of the judgments is however often contradictory.