In humans, 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. These parts will have different levels of sensitivity to androgens, primarily of the testosterone family.
The pubic area is particularly sensitive to such hormones, as are the armpits which will develop axillary hair. Pubic and axillary hair will develop on both men and women, to the extent that such hair qualifies as a secondary sex characteristic, although males will develop terminal hair in more areas. This includes facial hair, chest hair, abdominal hair, leg and arm hair, and foot hair. Human females on the other hand can be expected to retain more of the vellus hair.
These hairs are present in the large apes but not in the small apes like gibbons and represent an evolutionary divergence.:193
- Marks, James G; Miller, Jeffery (2006). Lookingbill and Marks' Principles of Dermatology (4th ed.), Elsevier Inc., p. 11. ISBN 1-4160-3185-5
- Hiort, O. "Androgens and Puberty". Best Practice & Research Clinical Endocrinology & Metabolism, Vol. 16, No. 1, pp. 31–41.
- Neal, Matthew; Lauren M. Sompayrac. How the Endocrine System Works. Blackwell Publishing, 2001, p. 75.
- 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.
- Heffner, Linda J. Human Reproduction at a Glance. Blackwell Publishing, 2001, p. 33.
- Robertson, James. Forensic Examination of Hair, CRC Press, 1999, p. 47.
- Neal, Matthew; Lauren M. Sompayrac. How the Endocrine System Works. Blackwell Publishing, 2001, pp. 70, 75.
- Kane, Jonathan; Willoughby, Emily; Michael Keesey, T. (2016-12-31). God's Word or Human Reason?: An Inside Perspective on Creationism. ISBN 9781629013725.