Abdominal hair

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Four typical patterns of male abdominal hair growth Abdominal hair patterns cmg.jpg
Four typical patterns of male abdominal hair growth

Abdominal hair is the hair that grows on the abdomen of humans and non-human mammals, in the region between the pubic area and the thorax (chest). The growth of abdominal hair follows the same pattern on nearly all mammals, vertically from the pubic area upwards and from the thorax downwards to the navel. The abdominal hair of non-human mammals is part of the pelage, (hair or fur).

Contents

It connects pubic hair and chest hair.

In humans

Before puberty, the abdominal region of both males and females is covered with very fine vellus hair. In response to rising levels of androgens (mainly dihydrotestosterone) during and after puberty, the skin of the abdomen begins to produce coarser, longer and more pigmented hair (terminal hair). This process primarily affects men. Initially, hair grows in a vertical line from the pubic area up to the navel and from the thorax down to the navel. The development of abdominal hair normally begins in the final stages of puberty. With some men, the abdominal hair will stay within a clearly defined vertical line, but in others, terminal hair will appear laterally as well as vertically, particularly in the area around the navel. This lateral spreading can continue into middle age.

Some women may develop a small line of hair from the pubic area up to the navel. Excessive abdominal hair on women, following the male pattern, is a type of hirsutism.

Patterns

Richard Zickler performed a 1997 study of photographs of the above patterns and their occurrence in 400 white men and 400 white women, [3] paying particular attention to the development of hair during puberty. In Zickler's study the horizontal pattern was most common in females with an incidence of about 80 percent. The acuminate pattern occurred in about 55 percent of males and occasionally in females. The disperse pattern occurred in about 19 percent of the males studied. [3]

See also

Related Research Articles

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Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testicles in a male. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Before puberty, the external sex organs, known as primary sexual characteristics, are sex characteristics that distinguish males and females. Puberty leads to sexual dimorphism through the development of the secondary sex characteristics, which further distinguish the sexes.

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References

  1. Setty LR (May 1966). "Varieties of the acuminate abdominal hair pattern of white males". J Natl Med Assoc. 58 (3): 191–3. PMC   2611109 . PMID   5932294.
  2. Setty LR (January 1967). "Varieties of the quadrangular abdominal hair pattern of white males". J Natl Med Assoc. 59 (1): 45–7. PMC   2611300 . PMID   6038587.
  3. 1 2 Zickler, Rienhard A. (1997). "Sex Differences in Pubic Hair Distribution in White Population". Archived from the original on August 17, 2011.

Further reading

The following journal articles include sketches of different abdominal hair patterns and observed percentages of men exhibiting each pattern.