Terminal hair

 ( Hair Anatomy ) 

In humans, terminal hair is a variant of hair that is thick and long such as that growing on the scalp, as compared with vellus hair, 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, 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 hair is particularly sensitive to such hormones, as are the armpits which will develop axillary hair.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,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, chest hair, abdominal hair, leg hair and arm hair, and foot hair.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.

• Body hair