Underarm hair
Human body hair From Wikipedia, the free encyclopedia
Underarm hair, also known as axillary hair or armpit hair, is the hair in the underarm area (axilla).
| Underarm hair | |
|---|---|
| Details | |
| Identifiers | |
| Latin | hirci |
| TA98 | A16.0.00.021 |
| TA2 | 7061 |
| FMA | 70756 |
| Anatomical terminology | |
Development
Underarm or axillary hair goes through four stages of development, as staged by the Wolfsdorf Axillary Hair Scale,[2] driven by weak androgens produced by the adrenal in males and females during adrenarche, and testosterone from the testicle in males during puberty.[3]
The Wolfsdorf Axillary Hair Staging system provides a standardized method for assessing pubertal progression and androgenic activity in pediatric populations. Similar to Tanner Staging for pubic hair, it classifies axillary hair growth into four stages:
- Wolfsdorf Stage 1 – No axillary hair
- Wolfsdorf Stage 2 – Sparse, soft hair
- Wolfsdorf Stage 3 – Coarser hair with increased volume
- Wolfsdorf Stage 4 – Full adult-like axillary hair
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).[4]
Male axilla
Female axilla
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.[5][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.[6]
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.[7]
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.[8]
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."[9] However, this was later proven to be false.[10]
See also
References
External links
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