Underarm hair

Underarm hair
Details
Identifiers
Latinhirci
TA98A16.0.00.021
TA27061
FMA70756
Anatomical terminology

Underarm hair, also known as axillary hair or armpit hair, is the hair in the underarm area (axilla).

Development

This is an illustration demonstrating the Wolfsdorf Staging for axillary hair development in children.[1]

Underarm or axillary hair goes through four stages of development, driven by weak androgens produced by the adrenal in males and females during adrenarche, and testosterone from the testicle in males during puberty.[2]

The importance of human underarm hair is unclear. It may naturally wick sweat or other moisture away from the skin, aiding ventilation. Colonization by odor-producing bacteria is thereby transferred away from the skin (see skin flora).[3]

  • Male axilla
    Male axilla
  • Female axilla
    Female axilla
  • Axillia of a pubescent male, note the short, stray hairs characteristic of this stage (Wolfsdorf 2)
    Axillia of a pubescent male, note the short, stray hairs characteristic of this stage (Wolfsdorf 2)

Function

Reducing friction

Armpit hair prevents skin-to-skin contact during activities that involve arm motion, such as running and walking. The same applies to pubic hair.[4][better source needed]

Spreading pheromones

The armpits release odor-containing pheromones, a naturally produced chemical that plays an important role in sexual attraction. Armpit hair traps odor, making the pheromones even stronger. A study in 2018 including 96 heterosexual couples found that there were stress-relieving benefits to smelling a romantic partner's natural scent.[5]

Impact of hair removal

Effect on odor

А 2012 study on the impact of hair removal on odor found that shaved armpits were rated the same as unshaved armpits.[6]

Chemical absorption

A 2017 study on chemical absorption from deodorants as a result of hair removal showed an increase in chemical absorption from .01% to .06% where skin has been damaged by recent shaving.[7]

A 2003 study on aluminum antiperspirant usage and the age of breast cancer onset tentatively concluded that "underarm shaving with antiperspirant/deodorant use may play a role in breast cancer."[8] However, this was later proven to be false.[9]

See also

References

  1. ^ Pineau, Jean-Claude (2020). "Age estimation of teenage boys during puberty". American Journal of Forensic Medicine and Pathology. 41 (3). Williams & Wilkins: 188–193. doi:10.1097/PAF.0000000000000573. PMID 32796206. S2CID 221257760.
  2. ^ Auchus RJ, Rainey WE (March 2004). "Adrenarche - physiology, biochemistry and human disease". Clinical Endocrinology. 60 (3): 288–296. doi:10.1046/j.1365-2265.2003.01858.x. PMID 15008992.
  3. ^ Paye M, Maibach HI, Barel AO (2009). Handbook of cosmetic science and technology (3 ed.). Informa Health Care. p. 703. ISBN 978-1-4200-6963-1.
  4. ^ "MRSA superbug? Part 1". PsycEXTRA Dataset. 2007. doi:10.1037/e721542007-001. Retrieved 12 July 2022.
  5. ^ Hofer MK, Collins HK, Whillans AV, Chen FS (January 2018). "Olfactory cues from romantic partners and strangers influence women's responses to stress". Journal of Personality and Social Psychology. 114 (1): 1–9. doi:10.1037/pspa0000110. PMID 29293018. S2CID 40410769.
  6. ^ Kohoutová D, Rubešová A, Havlíček J (April 2012). "Shaving of axillary hair has only a transient effect on perceived body odor pleasantness". Behavioral Ecology and Sociobiology. 66 (4): 569–581. Bibcode:2012BEcoS..66..569K. doi:10.1007/s00265-011-1305-0. ISSN 0340-5443. S2CID 16607684.
  7. ^ Klotz K, Weistenhöfer W, Neff F, Hartwig A, van Thriel C, Drexler H (September 2017). "The Health Effects of Aluminum Exposure". Deutsches Ärzteblatt International. 114 (39): 653–659. doi:10.3238/arztebl.2017.0653. PMC 5651828. PMID 29034866.
  8. ^ McGrath KG (December 2003). "An earlier age of breast cancer diagnosis related to more frequent use of antiperspirants/deodorants and underarm shaving". European Journal of Cancer Prevention. 12 (6): 479–485. doi:10.1097/00008469-200312000-00006. PMID 14639125. S2CID 24938503.
  9. ^ Mousavi, Maryam; Vaghar, Mohammad I (January 2021). "The relationship between use of aluminum-containing anti-perspirant and hair color with breast cancer". Journal of Family Medicine and Primary Care. 10 (1): 182–186. doi:10.4103/jfmpc.jfmpc_1219_19. ISSN 2249-4863. PMC 8132781. PMID 34017723.