Abdominal hair
Encyclopedia
Hair
Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....
that grows on the abdomen of humans and non-human mammals, in the region between the pubic area and the thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
(chest
Chest
The chest is a part of the anatomy of humans and various other animals. It is sometimes referred to as the thorax or the bosom.-Chest anatomy - Humans and other hominids:...
). 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 umbilicus
Navel
The navel is a scar on the abdomen caused when the umbilical cord is removed from a newborn baby...
(navel
Navel
The navel is a scar on the abdomen caused when the umbilical cord is removed from a newborn baby...
). The abdominal hair of non-human mammals is part of the pelage or fur
Fur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...
.
In humans
Before pubertyPuberty
Puberty is the process of physical changes by which a child's body matures into an adult body capable of reproduction, as initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy...
, the abdominal region of both males and females is covered with very fine vellus hair. In response to rising levels of androgens (mainly testosterone
Testosterone
Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands...
) during and after puberty, the skin of the abdomen begins to produce coarser, longer and more pigmented hair (terminal hair
Terminal hair
Terminal hairs are thick, long, and dark, as compared with vellus hair. During puberty, the increase in androgenic hormone levels causes vellus hair to be replaced with terminal hair in certain parts of the human body...
). This process affects primarily men. Initially hair grows in a vertical line from the pubic area up to the navel and from the thorax down to the navel. Slang terms for this line of hair include "snail trail", "happy line", "happy trail", or "treasure trail". Although the development of abdominal hair normally begins during puberty, it may also start later, between the ages of 20 and 30. 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. The study noted below found that two in three young men have a (sagittal) "treasure trail" by the time they are seventeen, and nearly half have one by time they are fifteen.
Some women may develop a small line of hair from the pubic area up to the navel. According to the female sex image in some cultures this is seen as desirable, and in others it is seen as unattractive. Excessive abdominal hair on women, following the male pattern, is a type of hirsutism
Hirsutism
Hirsutism or frazonism is the excessive hairiness on women in those parts of the body where terminal hair does not normally occur or is minimal - for example, a beard or chest hair. It refers to a male pattern of body hair and it is therefore primarily of cosmetic and psychological concern...
.
Patterns
Caucasian race
The term Caucasian race has been used to denote the general physical type of some or all of the populations of Europe, North Africa, the Horn of Africa, Western Asia , Central Asia and South Asia...
subjects have documented four general patterns of pubic and abdominal hair including:
- Horizontal — Characterized by upper surface of pubic hairPubic hairPubic hair is hair in the frontal genital area, the crotch, and sometimes at the top of the inside of the legs; these areas form the pubic region....
terminating in a horizontal line with no hair extending to the abdomen. - Sagittal — Resembles the first but with the addition of a narrow vertical band of hair extending from the pubic hair towards the navel, often slang called a 'Snail Trail', 'Treasure Trail' or 'Happy Trail'.
- Acuminate — Characterized by a tapered, inverted 'V' pattern extending upward from the pubic hair. Upper limit may end below the navel, at the navel, above the navel or near the chest.
- Disperse (or quadrangular) — Hair is distributed broadly over the abdomen without forming a discrete geometric pattern.
Richard Zickler performed a 1997 study (see citation below) of the above patterns and their occurrence in males and females, 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. This pattern occurred in 6% of males, including 55% of 13–15 year olds and 28% of 16 and 17 year olds. The sagittal pattern was found in 44% of males under 16, 67% of males aged 16–17, 20% of males over 17, and 17% of females. 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.
Further reading
The following journal articles include sketches of different abdominal hair patterns and observed percentages of men exhibiting each pattern.- See Setty's articles in references.
See also
- HairHairHair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....
- Pubic hairPubic hairPubic hair is hair in the frontal genital area, the crotch, and sometimes at the top of the inside of the legs; these areas form the pubic region....
- Chest hairChest hairThe term chest hair is generally used to describe hair that grows on the chest of human males, in the region between the neck and the abdomen. Chest hair, which is a secondary sex characteristic, develops during and after puberty...
- UmbilicusNavelThe navel is a scar on the abdomen caused when the umbilical cord is removed from a newborn baby...