![VellushaarTerminalhaar-translation](https://upload.wikimedia.org/wikipedia/commons/2/2e/VellushaarTerminalhaar-translation.JPG)
In humans, terminal hair is a variant of hair that is thick and long such as what grows on the scalp, as compared with
vellus hair
Vellus hair is short, thin, light-colored, and barely noticeable hair that develops on most of a human’s body during childhood. Exceptions include the lips, the back of the ear, the palm of the hand, the sole of the foot, some external genital ...
, colloquially known as peach fuzz, growing elsewhere.
[Marks, James G; Miller, Jeffery (2006)]
''Lookingbill and Marks' Principles of Dermatology''
(4th ed.), Elsevier Inc., p. 11. During
puberty
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 girl, the testes in a boy. ...
, the increase in androgenic hormone levels causes vellus hair to be replaced with terminal hair in certain parts of the human body.
[Hiort, O. "Androgens and Puberty". ''Best Practice & Research Clinical Endocrinology & Metabolism'', Vol. 16, No. 1, pp. 31–41.] These parts will have different levels of sensitivity to androgens, primarily of the testosterone family.
[Neal, Matthew; Lauren M. Sompayrac]
''How the Endocrine System Works''
Blackwell Publishing, 2001, p. 75.
The
pubic area
Pubic hair is terminal body hair that is found in the genital area of adolescent and adult humans. The hair is located on and around the sex organs and sometimes at the top of the inside of the thighs. In the pubic region around the pubis bone ...
is particularly sensitive to such hormones, as are the armpits which will develop
axillary hair
Underarm hair, also known as axillary hair, is the hair in the underarm area (''axilla'').
Development
Underarm or axillary hair goes through four stages of development, driven by weak androgens produced by the adrenal in males and females dur ...
.
[Randall, Valerie A.; Nigel A. Hibberts, M. Julie Thornton, Kazuto Hamada, Alison E. Merrick, Shoji Kato, Tracey J. Jenner, Isobel De Oliveira, Andrew G. Messenger. "The Hair Follicle: A Paradoxical Androgen Target Organ", ''Hormone Research'', Vol. 54, No. 5–6, 2000.] Pubic and axillary hair will develop on both men and women, to the extent that such hair qualifies as a
secondary sex characteristic
Secondary sex characteristics are features that appear during puberty in humans, and at sexual maturity in other animals. These characteristics are particularly evident in the sexually dimorphic phenotypic traits that distinguish the sexes of a sp ...
,
[Heffner, Linda J. ''Human Reproduction at a Glance''. Blackwell Publishing, 2001, p. 33.] although males will generally develop terminal hair in more areas. This includes
facial hair
Facial hair is hair grown on the face, usually on the chin, cheeks, and upper lip region. It is typically a secondary sex characteristic of human males. Men typically start developing facial hair in the later stages of puberty or adolescence, ...
,
chest hair
Chest hair is hair that grows on the chest in the region between the neck and the abdomen. Chest hair develops during and after puberty along with other types of androgenic hair.
Development and growth
Although vellus hair is already present ...
,
abdominal hair
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 pub ...
,
leg
A leg is a weight-bearing and animal locomotion, locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single ...
and
arm hair
Body hair, or androgenic hair, is the terminal hair that develops on the human body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which is much finer and lighter in color. The growth of androge ...
, and
foot hair
Body hair, or androgenic hair, is the terminal hair that develops on the human body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which is much finer and lighter in color. The growth of androg ...
.
[Robertson, James]
''Forensic Examination of Hair''
CRC Press, 1999, p. 47. Human females on the other hand generally retain more of the vellus hair.
[Neal, Matthew; Lauren M. Sompayrac. ''How the Endocrine System Works''. Blackwell Publishing, 2001, pp. 70, 75.]
These hairs are present in the large apes but not in the small apes like gibbons and represent an evolutionary divergence.
See also
*
Body hair
Body hair, or androgenic hair, is the terminal hair that develops on the human body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which is much finer and lighter in color. The growth of androge ...
References
{{Human hair
Hair anatomy