Exclusively under the feet and on the palms, humans do not have it: the body hair. Approximately 5 million hairs are distributed on the body of man and still act a little like once the fur, which protected the animals and people from environmental influences. In the course of evolution and the life of each individual, body hair changes.
What is body hair?
Approximately 5 million hairs are distributed on the body of man, only under the feet and on the palms of the hands man has no body hair. Already at infancy, the entire body (except palms and inner surfaces of the feet) is covered with a colorless, fine downy hair. Between the 8th and 14th year of life, the hairs on the body and in the genital area begin to become stronger. In the course of life, they become more intense step by step. In the genital area, the hairs grow first. They form on the labia, on the inner thighs, around the penis and on the scrotum. The thickness of the hair is predisposition and varies from person to person. The beard starts to grow between the ages of 15 and 19. Normally, the hair on the chest begins at the end of puberty, around the age of 17. However, it can also start at a later age (between about 20 and 30 years). Not all men get chest hair or intense beard growth and not all women do not get chest hair or beard growth. Again, genes play a crucial role.
Function and task
Body hair includes all the hair on the body. Androgenic hair growth is influenced by androgen secretion. Except for head hair and beard hair, the growth cycle of body hair is limited to a few months and is thus much shorter than that of head hair. Terminal or adult body hair begins to develop at puberty and is not present until increased androgens are secreted. Men and women tend to have different levels of androgen secretion, which causes the terminal body hair to differ between men and women. Body hair is thus a secondary sex characteristic. Body hair protects humans from UV radiation, parasites as well as pathogens. The terminal hairiness also supports temperature regulation. Under sweat gland-rich places on the body, such as the armpits, the hair increases the surface, whereby sweat can be easily removed. In addition to increasing the surface area of the body, body hair also increases the sensitivity of the skin. The hairs transmit touches to the skin early and there is an increased effect. In addition, the hairs provide protection against blood-sucking ectoparasites, because the amplification effect makes people feel parasites such as mosquitoes, bed bugs or ticks more quickly. Another advantage is that the bloodsuckers need significantly more time to find a suitable puncture site in the tangle of hair. For the pubic area, the dense hairiness provides additional protection and ensures that friction is reduced. In early times, the ancestors of man still possessed a kind of fur. This coat has become thinner and thinner throughout history. Nevertheless, the warming function is still slightly preserved. In addition, small muscles attach to the hair follicles. When these muscles contract, the hair straightens in the process. This straightening of the hair protects against the cold, because the contraction reduces blood flow to the affected area and the straightened hair creates an insulating layer of air through which body heat escapes more slowly. The eyelashes, nose hairs or ear hairs protect the corresponding sensory organs from foreign bodies. Eyebrows protect the eyes from sweat running from the forehead.
Diseases and ailments
Hypertrichosis is the term used to describe an increased growth of body hair. The phenomenon can occur in both sexes in different strength and at different ages. In the male sex, hypertrichosis is recognized when there is a very pronounced body hair on the abdomen, back or neck. Women, on the other hand, in this case have a hair growth on the upper lip (upper lip beard) or on the chin. Sometimes women also have a strong hair growth on the forearms or in the butt fold. Hirsutism can occur only in the female sex.The hair growth here corresponds to male body hair. Affected individuals suffer from hair growth on the chin, upper lip, back, abdomen or upper arms. The reason can be a hormonal irregularity. In most cases, however, no underlying disease can be detected. In some cases, hair growth is accompanied by some other typically male changes. These include, for example, a deep voice and balding. If these symptoms occur, the term virilization or masculinization is used. This is triggered by an increased formation of male sex hormones. The idea of ideal hair growth varies from culture to culture. In Western cultures, male hair is usually more accepted than female hair. With regard to strong body hair, the question therefore arises as to how far hirsutism and hypertrichosis are to be evaluated as diseases at all. The phenomena do not have any negative effects on the body, but are ultimately only contrary to the social ideas of what is considered normal on average. Just as, with regard to hirsutism, there are men who have little body hair (which in turn is not evaluated as a disease), there are women who have a lot of body hair. This primarily has a stressful effect on the psyche, as it is contrary to the feminine ideal. In general, the biological boundaries between man and woman as opposite sexes are not as clear as we socially imagine them to be. “Masculinization,” in the absence of other symptoms, may therefore well be seen as a normal manifestation within the scale of human sex. However, if increased body hair suddenly appears, a doctor should be consulted urgently. This is because such increased body hair may indicate a tumor, hypothyroidism, or hormonal imbalance.
