Underarm hair

Axillary hair, also known as underarm hair, is the composition of hair in the underarm area. This hair, as most of the other body hair, normally starts to appear at puberty and growth is usually complete by the end of teen age. The release of pheromones from the axilla at this stage of human development suggests association of armpit hair with sexuality. The positive response to olfactory stimulus in mammals and the consequent intensification of the sex drive caused by release of pheromones offers useful clues as to the purpose and importance of axillary hair in humans. It has been suggested that the hair itself acts with a natural "anti-friction" quality between the upper arm and the thorax.

Cultural attitudes
Today, in many countries, especially in much of the Western world, it is more common for women than men to shave off their underarm hair regularly for aesthetic reasons, a practice that may be connected to the overall body hair distribution of sexes. Prevalence of this practice varies widely, though. Some Western women sport a stubble as a mark of defiance against imposed cultural mores. In some East European countries as well as China, underarm shaving is less common and is not considered esthetically necessary.

Religious reasons and personal cleanliness requirements are sometimes cited; in Islamic culture, both men and women practice the removal of underarm hair for reasons of cleanliness. Underarm hair does provide increased surface area on which the bacteria can thrive, deodorants and antiperspirants have come to counterbalance these issues to a great extent, though.

Competitive swimmers remove all body hair, including underarms, to make their bodies more streamlined before taking part in races. It is also common amongst bodybuilders, for aesthetic reasons.

History of underarm hair removal
In the West, the practice began around 1915 in the US and UK, when one or more magazines showed a woman in a dress with shaved underarms. Regular shaving became feasible with the introduction of the safety razor at the beginning of the 20th century. While underarm shaving was quickly adopted in English speaking countries, especially in the US and Canada, it did not become widespread on the Continent of Europe until well after WWII.

Effects of shaving
It is a commonly believed myth that shaving hair will cause it to grow thicker over time. There is nothing about the practice of shaving that produces new follicles for hair to grow out of; this myth most likely persists because stubble does not taper like hair that is allowed to grow long and because short hairs feel coarser than longer hairs of the same thickness. Armpit hair removal must be performed more frequently than leg shaving, as underarm hair grows faster than leg hair. The armpit area can darken over a period of time and even with a close shave, an "evening shadow" may be visible. Because hair under the skin can contribute to a dark appearance of the underarm, waxing, by removing the hair from the root, can effectively reduce this darkness.