Glabrousness (from the Latin glaber meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, such as alopecia universalis in humans, which causes hair to fall out or not regrow. Humans may also intentionally remove some or all of their body hair for a variety of cultural reasons.
Glabrousness or otherwise, of leaves, stems, and fruit is a feature commonly mentioned in plant keys; in botany and mycology, a glabrous morphological feature is one that is smooth and may be glossy. It has no bristles or hair-like structures such as trichomes. In anything like the zoological sense, no plants or fungi have hair or wool, although some structures may resemble such materials.
The term "glabrous" strictly applies only to features that lack trichomes at all times. When an organ bears trichomes at first, but loses them with age, the term used is glabrescent.
In the model plant Arabidopsis thaliana, trichome formation is initiated by the GLABROUS1 protein. Knockouts of the corresponding gene lead to glabrous plants. This phenotype has already been used in gene editing experiments and might be of interest as visual marker for plant research to improve gene editing methods such as CRISPR/Cas9.
In varying degrees most mammals have some skin areas without natural hair. On the human body, glabrous skin is found on the ventral portion of the fingers, palms, soles of feet and lips, which are all parts of the body most closely associated with interacting with the world around us, as are the labia minora and glans penis. There are four main types of mechanoreceptors in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles.
The Naked mole-rat (Heterocephalus glaber) has evolved skin lacking in general, pelagic hair covering, yet has retained long, very sparsely scattered tactile hairs over its body. Glabrousness is a trait that may be associated with neoteny.
The term glabrousness also has been applied to human fashions, wherein some participate in culturally motivated hair removal by depilation (surface removal by shaving, dissolving), or epilation (removal of the entire hair, such as waxing or plucking).
Although the appearance of secondary hair on parts of the human body commonly occurs during puberty, and therefore, is often seen as a symbol of adulthood, removal of this and other hair may become fashionable in some cultures and subcultures. In many modern Western cultures, men currently are encouraged to shave their beards, and women are encouraged to remove hair growth on various areas. Commonly depilated areas for women are the underarms and legs. Pubic hair may be removed partially or entirely. Some individuals depilate the forearms. In recent years, bodily depilation in men has increased in popularity among some subcultures of Western males.
As with any cosmetic practice, the particulars of hair removal have changed over the years. Western female depilation has been significantly influenced by the evolution of clothing in the past century. Leg and underarm shaving became popular again[when?] in some parts of Western society with the advent of off-the-shoulder dresses, higher hemlines, and transparent stockings. The reduction of the minimum acceptable standards for bodily coverage over recent years has resulted in the exposure of more flesh, giving rise to more extensive hair removal in some cultures.
Encouragement by commercial interests may be seen in advertising. At present, this has resulted in the "Brazilian waxing" trend involving the partial or full removal of pubic hair, as the thongs worn on Brazilian beaches are too small to conceal very much of it. Indeed, a culture is now emerging around "intimate shaving" and other hair removal options geared specifically toward pubic hair. (cf. bikini waxing) What was once kept a personal secret now is discussed more openly, although still in carefully non-explicit language, as advertised in magazines and on television.[original research?]
For men the practice of depilating the pubic area is commonly referred to as manscaping, even though technically this term is applicable to hair removal all over the body. Many men will try this at some point in their lives, especially for aesthetic reasons because shaving the pubic area will optically enhance the size of the male penis. There is a popular saying with reference to this practice which goes 'when you trim the bush, the tree will look bigger'. Most men will use a razor to shave this area, however as best practice, it is recommended to use a body trimmer to shorten the length of the hair before shaving it off completely.
In ancient Egypt, depilation was commonly practiced, with pumice and razors used to shave. In both Ancient Greece and Ancient Rome, the removal of body and pubic hair may have been practiced among both men and women. It is represented in some artistic depictions of male and female nudity, examples of which may be seen in some red figure pottery of Ancient Greece on which both men and women were depicted without body or pubic hair.
In the clothes free movement, the term "smoothie" refers to an individual who has removed most of their hair. In the past, such practices were frowned upon and in some cases, members of clothes-free clubs were forbidden to remove their pubic hair: violators could face exclusion from the club. Enthusiasts grouped together and formed societies of their own that catered to that fashion and the fashion became more popular, with smoothies becoming a major percentage at some nudist venues. The first Smoothie club (TSC) was founded by a British couple in 1991. A Dutch branch was founded in 1993 in order to give the idea of a hairless body greater publicity in the Netherlands. Being a Smoothie is described by its supporters as exceptionally comfortable and liberating. The Smoothy-Club is also a branch of the World of the Nudest Nudist (WNN) and organizes nudist ship cruises and nudist events every month. Every year in spring the club organizes the international Smoothy days. In the U.K. the SCN Naturist Club for "Smooth Ladies and Smooth and Circumcised Gentlemen" was formed in 1996. Although the SCN club closed in 2001 after five years, its SCN website continues to promote the club's hairless fashion.
Athletes may depilate as an enhancement to their abilities. For example, male and female competitive swimmers may remove their body and pubic hair in order to help streamline their bodies and to allow their swimsuits to fit more closely to their bodies. Bicyclists also remove body hair to decrease the effects of "road rash" by minimizing the tearing action of hair against pavement during a bike crash and to provide easier injury clean-up afterward. Hairfree legs also are described as increasing the comfort and effectiveness of sport massages.
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