HOME

TheInfoList




Hair is a
protein filament In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms, ...

protein filament
that grows from
follicles
follicles
found in the
dermis The dermis or corium is a layer of skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such a ...
. Hair is one of the defining characteristics of
mammal Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republ ...
s. The
human body The human body is the structure of a human being Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of ...

human body
, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine
vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of g ...
. Most common interest in hair is focused on
hair growth The growth of human hair occurs everywhere on the body except for the soles of the feet, the inside of the mouth, the lips, the backs of the ears, the palms of the hands, some external genital A sex organ (or reproductive organ) is any part of a ...
, hair types, and
hair care Hair care is an overall term for hygiene Hygiene is a series of practices performed to preserve health Health, according to the World Health Organization, is "a state of complete physical, Mental health, mental and social well-being and no ...
, but hair is also an important
biomaterial A biomaterial is a substance that has been engineered to interact with biological systems for a medical purpose, either a therapeutic (treat, augment, repair, or replace a tissue function of the body) or a diagnostic one. As a science, biomateria ...
primarily composed of
protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

protein
, notably
alpha-keratin Alpha-keratin, or α-keratin, is a type of keratin Keratin () is one of a family of fibrous structural proteins known as Scleroprotein, scleroproteins. ''Alpha-keratin, α-Keratin'' is a type of keratin found in vertebrates. It is the key structu ...
. Attitudes towards different forms of hair, such as
hairstyle of a Japanese bride '' with braided hair A hairstyle, hairdo, haircut or coiffure refers to the fashion, styling of hair Hair is a protein filament In biology Biology is the natural science that studies life and living orga ...

hairstyle
s and
hair removal Hair removal, also known as epilation or depilation, is the deliberate removal of body hair Body hair, or androgenic hair, is the terminal hair that develops on the human body The human body is the structure of a human being. It is compose ...
, vary widely across different cultures and historical periods, but it is often used to indicate a person's personal beliefs or social position, such as their age, sex, or
religion Religion is a - of designated and practices, , s, s, , , , , or , that relates humanity to , , and elements; however, there is no scholarly consensus over what precisely constitutes a religion. Different religions may or may not contain v ...

religion
.


Overview

The word "hair" usually refers to two distinct structures: #the part beneath the skin, called the
hair follicle The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given orga ...

hair follicle
, or, when pulled from the skin, the bulb or root. This organ is located in the
dermis The dermis or corium is a layer of skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such a ...
and maintains
stem cell In multicellular organisms Multicellular organisms are organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties o ...
s, which not only re-grow the hair after it falls out, but also are recruited to regrow skin after a
wound A wound is a type of which happens relatively quickly in which is torn, cut, or punctured (an ''open'' wound), or where blunt force causes a (a ''closed'' wound). In , it specifically refers to a sharp injury which damages the of the skin. ...

wound
. # the hair shaft, which is the hard filamentous part that extends above the skin surface. A cross section of the hair shaft may be divided roughly into three zones. Hair fibers have a structure consisting of several layers, starting from the outside: # the
cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-homology (biology), homologous, differing in the ...
, which consists of several layers of flat, thin cells laid out overlapping one another as roof shingles # the
cortex Cortex or cortical may refer to: Science Anatomy * Cortex (anatomy), the outermost or superficial layer of an organ * Cortex (hair), the middle layer of a strand of hair * Adrenal cortex, the portion of the adrenal gland that produces cortisol and ...
, which contains the
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin Alpha-keratin, or α-keratin, is a type of keratin Keratin () is one of a family of fibrous structural proteins known as Scleroprot ...

keratin
bundles in cell structures that remain roughly rod-like # the
medulla Medulla or Medullary may refer to: Science * Medulla oblongata The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is ...
, a disorganized and open area at the fiber's center


Description

Each strand of hair is made up of the
medulla Medulla or Medullary may refer to: Science * Medulla oblongata The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is ...
,
cortex Cortex or cortical may refer to: Science Anatomy * Cortex (anatomy), the outermost or superficial layer of an organ * Cortex (hair), the middle layer of a strand of hair * Adrenal cortex, the portion of the adrenal gland that produces cortisol and ...
, and
cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-homology (biology), homologous, differing in the ...
.Hair Structure and Hair Life Cycle
follicle.com
The innermost region, the
medulla Medulla or Medullary may refer to: Science * Medulla oblongata The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is ...
, is not always present which is an open, unstructured region. The highly structural and organized
cortex Cortex or cortical may refer to: Science Anatomy * Cortex (anatomy), the outermost or superficial layer of an organ * Cortex (hair), the middle layer of a strand of hair * Adrenal cortex, the portion of the adrenal gland that produces cortisol and ...
, or second of three layers of the hair, is the primary source of mechanical strength and water uptake. The cortex contains
melanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the ami ...

melanin
, which colors the
fiber Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including ...

fiber
based on the number, distribution and types of
melanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the ami ...

melanin
granules. The shape of the follicle determines the shape of the cortex, and the shape of the
fiber Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including ...

fiber
is related to how straight or curly the hair is. People with straight hair have round hair fibers. Oval and other shaped fibers are generally more wavy or curly. The cuticle is the outer covering. Its complex structure slides as the hair swells and is covered with a single molecular layer of
lipid In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanis ...
that makes the hair repel water. The diameter of human hair varies from . There are two million small, tubular glands and
sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of an ...
s that produce watery fluids that cool the body by evaporation. The glands at the opening of the hair produce a fatty secretion that lubricates the hair. Hair growth begins inside the
hair follicle The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given orga ...

hair follicle
. The only "living" portion of the hair is found in the follicle. The hair that is visible is the hair shaft, which exhibits no biochemical activity and is considered "dead". The base of a hair's root (the "bulb") contains the cells that produce the hair shaft. Other structures of the hair follicle include the oil producing
sebaceous gland A sebaceous gland is a microscopic exocrine Exocrine glands are gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormone A hormone (from the Greek participle , "setting in motion") is a ...
which lubricates the hair and the
arrector pili The arrector pili muscles, also knows as hair erector muscles, are small muscles attached to hair follicles The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with si ...
muscles, which are responsible for causing hairs to stand up. In humans with little body hair, the effect results in
goose bumps Goose bumps, goosebumps or goose-pimples are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is tickled, cold , a common physiological response to cold, aiming to reduce the loss of bo ...

goose bumps
.


Root of the hair

The ''root of the hair'' ends in an enlargement, the ''hair bulb'', which is whiter in color and softer in texture than the shaft and is lodged in a follicular involution of the
epidermis The epidermis is the outermost of the three layers that comprise the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of animal Animals (also calle ...
called the
hair follicle The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given orga ...

hair follicle
. The bulb of hair consists of fibrous connective tissue, glassy membrane, external root sheath, internal root sheath composed of epithelium stratum (
Henle's layer Henle's layer is the third and the outermost layer of the inner root sheath of the hair follicle, consisting of a single layer of cubical cells with clear flattened nuclei. It is named after Germany, German physician, pathologist and anatomist Frie ...
) and granular stratum ( Huxley's layer), cuticle, cortex and medulla.


Natural color

All natural hair colors are the result of two types of hair pigments. Both of these pigments are melanin types, produced inside the hair follicle and packed into granules found in the fibers.
Eumelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
is the dominant pigment in
brown hair Brown hair is the second most common human hair color Hair color is the pigmentation of hair follicles due to two types of melanin: eumelanin and pheomelanin. Generally, if more melanin is present, the color of the hair is darker; if less mel ...

brown hair
and
black hair Black hair is the darkest and most common of all human hair colors globally, due to larger populations with this dominant trait. It is a dominant genetic trait, and it is found in people of all backgrounds and ethnicities. It has large amounts ...
, while
pheomelanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at ...
is dominant in
red hair Red hair (also known as orange hair and ginger hair) is a hair colour found in one to two percent of the human population Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalit ...

red hair
.
Blond hair Blond or fair hair is a Human hair color, hair color characterized by low levels of the dark pigment eumelanin. The resultant visible hue depends on various factors, but always has some yellowish color. The color can be from the very pale blond ...
is the result of having little
pigmentation A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes 300px, Yarn drying after being dyed in the early American tradition, at living_history_museum.html"_;"title="Conner_Prairie_living_history_muse ...
in the hair strand.
Gray hair Hair color is the pigmentation of hair follicle The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regul ...
occurs when melanin production decreases or stops, while poliosis is white hair (and often the skin to which the hair is attached), typically in spots that never possessed melanin at all, or ceased for natural reasons, generally genetic, in the first years of life.


Human hair growth

Hair grows everywhere on the external body except for
mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membrane A mucous membrane or mucosa is a biological membrane, membrane that lines various cavities in the body and covers the surface of internal organs. It consists o ...
membranes and glabrous skin, such as that found on the palms of the hands, soles of the feet, and lips. Hair follows a specific growth cycle with three distinct and concurrent phases:
anagen The hair follicle is an Organ (anatomy), organ found in mammalian skin. It resides in the Dermis, dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a comple ...
, catagen, and telogen phases; all three occur simultaneously throughout the body. Each has specific characteristics that determine the length of the hair. The body has different types of hair, including
vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of g ...
and
androgenic hair Body hair, or androgenic hair, is the terminal hair In humans, terminal hair is thick and long, such as what grows on the scalp, as compared with vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is ...

androgenic hair
, each with its own type of cellular construction. The different construction gives the hair unique characteristics, serving specific purposes, mainly, warmth and protection.


Texture

Hair exists in a variety of textures. Three main aspects of hair texture are the curl pattern, volume, and consistency. The derivations of hair texture are not fully understood. All mammalian hair is composed of
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin Alpha-keratin, or α-keratin, is a type of keratin Keratin () is one of a family of fibrous structural proteins known as Scleroprot ...

keratin
, so the make-up of
hair follicles The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given orga ...

hair follicles
is not the source of varying hair patterns. There are a range of theories pertaining to the curl patterns of hair. Scientists have come to believe that the shape of the
hair shaft Hair is a protein filament that grows from hair follicle, follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick ...
has an effect on the curliness of the individual's hair. A very round shaft allows for fewer
disulfide bonds In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they underg ...

disulfide bonds
to be present in the hair strand. This means the bonds present are directly in line with one another, resulting in straight hair. The flatter the hair shaft becomes, the curlier hair gets, because the shape allows more
cysteine Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the chemical formula, formula HOOC-CH-(NH2)-CH2-SH. The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. The thiol is suscepti ...

cysteine
s to become compacted together resulting in a bent shape that, with every additional disulfide bond, becomes curlier in form. As the hair follicle shape determines curl pattern, the hair follicle size determines thickness. While the circumference of the hair follicle expands, so does the thickness of the hair follicle. An individual's hair volume, as a result, can be thin, normal, or thick. The consistency of hair can almost always be grouped into three categories: fine, medium, and coarse. This trait is determined by the hair follicle volume and the condition of the strand. Fine hair has the smallest circumference, coarse hair has the largest circumference, and medium hair is anywhere between the other two. Coarse hair has a more open cuticle than thin or medium hair causing it to be the most porous.


Classification systems

There are various systems that people use to classify their curl patterns. Being knowledgeable of an individual's hair type is a good start to knowing how to take care of one's hair. There is not just one method to discovering one's hair type. Additionally it is possible, and quite normal to have more than one kind of hair type, for instance having a mixture of both type 3a & 3b curls. ; The Andre Walker Hair Typing System is the most widely used system to classify hair. The system was created by the hairstylist of
Oprah Winfrey Oprah Gail Winfrey (born Orpah Gail Winfrey; January 29, 1954) is an American talk show host, television producer, actress, author, and philanthropist. She is best known for her talk show, '' The Oprah Winfrey Show'', broadcast from Chicag ...

Oprah Winfrey
, Andre Walker. According to this system there are four types of hair: straight, wavy, curly, kinky. * Type 1 is straight hair, which reflects the most sheen and also the most resilient hair of all of the hair types. It is hard to damage and immensely difficult to curl this hair texture. Because the
sebum A sebaceous gland is a microscopic exocrine Exocrine glands are gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormone A hormone (from the Greek participle , "setting in motion") is a ...

sebum
easily spreads from the scalp to the ends without curls or kinks to interrupt its path, it is the most oily hair texture of all. * Type 2 is wavy hair, whose texture and sheen ranges somewhere between straight and curly hair. Wavy hair is also more likely to become
frizz Frizz is hair Hair is a protein filament In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular in ...

frizz
y than straight hair. While type A waves can easily alternate between straight and curly styles, type B and C Wavy hair is resistant to styling. * Type 3 is
curly hair Hair is a protein filament that grows from hair follicle, follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick t ...

curly hair
known to have an S-shape. The curl pattern may resemble a lowercase "s", uppercase "S", or sometimes an uppercase "Z" or lowercase "z". This hair type is usually voluminous, "climate dependent (
humidity Humidity is the concentration of water vapor, water vapour present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, d ...

humidity
= frizz), and damage-prone." Lack of proper care causes less defined curls. * Type 4 is kinky hair, which features a tightly coiled curl pattern (or no discernible curl pattern at all) that is often fragile with a very high density. This type of hair shrinks when wet and because it has fewer
cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-homology (biology), homologous, differing in the ...
layers than other hair types it is more susceptible to damage. ; This is a method which classifies the hair by curl pattern, hair-strand thickness and overall hair volume.


Functions

Many mammals have
fur Fur is a thick growth of hair Hair is a protein filament In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular bi ...

fur
and other hairs that serve different functions. Hair provides thermal regulation and
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard The leopard (''Pan ...

camouflage
for many animals; for others it provides signals to other animals such as warnings, mating, or other communicative displays; and for some animals hair provides defensive functions and, rarely, even offensive protection. Hair also has a sensory function, extending the sense of touch beyond the surface of the skin. Guard hairs give warnings that may trigger a recoiling reaction.


Warmth

While humans have developed clothing and other means of keeping warm, the hair found on the head serves primarily as a source of heat and cooling (when sweat evaporates from soaked hair) as well as protection from ultra-violet radiation exposure. The function of hair in other locations is debated. Hats and coats are still required while doing outdoor activities in cold weather to prevent
frostbite Frostbite is a skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod ...

frostbite
and
hypothermia Hypothermia is defined as a body core temperature Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal- ...
, but the hair on the human body does help to keep the internal temperature regulated. When the body is too cold, the
arrector pili The arrector pili muscles, also knows as hair erector muscles, are small muscles attached to hair follicles The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with si ...
muscles found attached to hair follicles stand up, causing the hair in these follicles to do the same. These hairs then form a heat-trapping layer above the
epidermis The epidermis is the outermost of the three layers that comprise the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of animal Animals (also calle ...
. This process is formally called
piloerection Goose bumps, goosebumps or goose-pimples are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is tickled, cold , a common physiological response to cold, aiming to reduce the loss of bod ...
, derived from the Latin words 'pilus' ('hair') and 'erectio' ('rising up'), but is more commonly known as 'having
goose bumps Goose bumps, goosebumps or goose-pimples are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is tickled, cold , a common physiological response to cold, aiming to reduce the loss of bo ...

goose bumps
' in English. This is more effective in other mammals whose fur fluffs up to create air pockets between hairs that insulate the body from the cold. The opposite actions occur when the body is too warm; the arrector muscles make the hair lie flat on the skin which allows heat to leave.


Protection

In some mammals, such as
hedgehog A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family (biology), family Erinaceidae. There are seventeen species of hedgehog in five genus, genera found throughout parts of Europe, Asia, and Africa, and in Ne ...

hedgehog
s and
porcupine Porcupines are large rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% ...

porcupine
s, the hairs have been modified into hard spines or quills. These are covered with thick plates of keratin and serve as protection against predators. Thick hair such as that of the lion's mane and grizzly bear's fur do offer some protection from physical damages such as bites and scratches.


Touch sense

Displacement and vibration of hair shafts are detected by hair follicle nerve receptors and nerve receptors within the skin. Hairs can sense movements of air as well as touch by physical objects and they provide sensory awareness of the presence of
ectoparasites Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...
. Some hairs, such as
eyelashes An eyelash or simply lash is one of the hairs that grows at the edge of the eyelid. It grows in one layer on the edge of the eyelids. Eyelashes protect the eye from debris, dust and small particles and perform some of the same functions as whiske ...
, are especially sensitive to the presence of potentially harmful matter.


Eyebrows and eyelashes

The
eyebrow An eyebrow is an area of short hairs above each eye Eyes are organs of the visual system The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the o ...

eyebrow
s provide moderate protection to the
eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light L ...

eye
s from
dirt Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty. Common types of dirt include: * Dust: a general powder of Organic matter, organic or Mineral, ...

dirt
,
sweat Perspiration, also known as sweating, is the production of fluids secreted by the sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin Skin is the layer of usually soft, fle ...

sweat
and
rain Rain is liquid water in the form of droplet Rain water flux from a canopy. Among the forces that govern drop formation: cohesion, Van der Waals force">Cohesion_(chemistry).html" ;"title="surface tension, Cohesion (chemistry)">cohesion, ...

rain
. They also play a key role in non-verbal
communication Communication (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power o ...

communication
by displaying emotions such as sadness, anger, surprise and excitement. In many other mammals, they contain much longer, whisker-like hairs that act as tactile sensors. The
eyelash An eyelash (also called lash) (Latin: ''Cilia'') is one of the hairs that grows at the edge of the eyelids. It grows in one layer on the edge of the upper and lower eyelids. Eyelashes protect the eye from debris, dust and small particles and pe ...
grows at the edges of the eyelid and protects the eye from dirt. The eyelash is to humans, camels, horses, ostriches etc., what
whiskers showing four major cranial groups of vibrissae: supraorbital (above the eye), mystacial (where a moustache would be), genal (on the cheek, far left), and mandibular (pointing down, under the snout). may be vibrissae. ''. with large macrovibrissa ...

whiskers
are to
cat The cat (''Felis catus'') is a domestic Domestic may refer to: In the home * Anything relating to the human home A home, or domicile, is a space used as a permanent or semi-permanent residence for an individual, group or family ...

cat
s; they are used to sense when dirt,
dust Dust is made of s of solid . On Earth, it generally consists of particles in the that come from various sources such as lifted by wind (an ), , and . Dust in homes is composed of about 20–50% dead . The rest, and in offices, and other ...
, or any other potentially harmful object is too close to the eye. The eye reflexively closes as a result of this
sensationSensation refers to the processing of sense Sense relates to any of the systems and corresponding organs involved in sensation, i.e. the physical process of responding to Stimulus (physiology), stimuli and providing data for perception. During sensa ...
.


Evolution

Hair has its origins in the common ancestor of mammals, the
synapsid Synapsids are a group of animals that includes mammals and every animal more closely related to mammals than to the other members of the amniote clade, such as reptiles and birds. Unlike other amniotes, they have a Skull#Fenestrae, temporal fenes ...

synapsid
s, about 300 million years ago. It is currently unknown at what stage the synapsids acquired mammalian characteristics such as
body hair Body hair, or androgenic hair, is the terminal hair that develops on the human body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which is much finer and lighter in color. The growth of androgenic ...
and
mammary gland A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organ (anatomy), organs such as the b ...
s, as the
fossil A fossil (from Classical Latin Classical Latin is the form of Latin language Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication used by humans, inc ...

fossil
s only rarely provide direct evidence for soft tissues. Skin impression of the belly and lower tail of a
pelycosaur The pelycosaurs (pronounced PEL-ih-ko-saurz) were previously considered an order, but are now only an informal grouping composed of basal or primitive Late Paleozoic synapsids, sometimes called "mammal-like reptiles". They consist of all syna ...
, possibly ''
Haptodus ''Haptodus'' is an extinct Extinction is the termination of a kind of organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chem ...

Haptodus
'' shows the basal synapsid stock bore transverse rows of rectangular
scute A scute or scutum (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roma ...
s, similar to those of a modern
crocodile Crocodiles (family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain the well-being of its members and of society. I ...

crocodile
, so the age of acquirement of hair logically couldn't have been earlier than ~299 ma, based on the current understanding of the animal's phylogeny. An exceptionally well-preserved skull of '''', a
therapsid Therapsida is a major group of eupelycosauria Eupelycosauria is a large clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic— ...

therapsid
from the
Upper Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous period million years ago (Mya), to the beginning of the Triassic period 251.902 Mya. It is the last period of the Pa ...
, shows smooth, hairless skin with what appears to be glandular depressions, though as a semi-aquatic species it might not have been particularly useful to determine the integument of terrestrial species. The oldest undisputed known fossils showing unambiguous imprints of hair are the
Callovian In the geologic timescale, the Callovian is an age (geology), age and stage (stratigraphy), stage in the Middle Jurassic, lasting between 166.1 ± 4.0 annum, Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, f ...
(late middle
Jurassic The Jurassic ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth ...
) ''
Castorocauda ''Castorocauda'' is an extinct, semi-aquatic, beaver Beavers are large, semiaquatic rodents in the genus ''Castor'' native to the temperate Northern Hemisphere. There are two extant species: the North American beaver (''Castor canade ...
'' and several contemporary
haramiyida Haramiyidans were a long lived lineage of mammaliaform cynodonts or mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the pr ...
ns, both near-mammal
cynodont The cynodonts ("dog teeth") (clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic—that is, composed of a common ancestor and all ...

cynodont
s, giving the age as no later than ~220 ma based on the modern phylogenetic understanding of these clades. See also the news item at More recently, studies on terminal
Permian The Permian ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth ...
Russia Russia ( rus, link=no, Россия, Rossiya, ), or the Russian Federation, is a country spanning Eastern Europe Eastern Europe is the eastern region of . There is no consistent definition of the precise area it covers, partly because th ...

Russia
n
coprolites A coprolite (also known as a coprolith) is fossilized feces Feces (American and British English spelling differences#ae and oe, or faeces) is the solid or semisolid remains of food that was not digested in the small intestine, and has b ...

coprolites
may suggest that non-mammalian synapsids from that era had fur. If this is the case, these are the oldest hair remnants known, showcasing that fur occurred as far back as the latest
Paleozoic The Paleozoic (or Palaeozoic) Era ( ; from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Eu ...
. Some modern mammals have a special gland in front of each
orbit In celestial mechanics, an orbit is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificial satellite around an object or po ...
used to preen the fur, called the
harderian gland The Harderian gland is a gland found within the eye's orbit In physics, an orbit is the gravitationally curved trajectory of an physical body, object, such as the trajectory of a planet around a star or a natural satellite around a planet. No ...
. Imprints of this structure are found in the skull of the small early mammals like ''Morganucodon'', but not in their
cynodont The cynodonts ("dog teeth") (clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic—that is, composed of a common ancestor and all ...

cynodont
ancestors like ''Thrinaxodon''. The hairs of the fur in modern animals are all connected to nerves, and so the fur also serves as a transmitter for sensory input. Fur could have evolved from sensory hair (whiskers). The signals from this sensory apparatus is interpreted in the neocortex, a section of the brain that expanded markedly in animals like ''Morganucodon'' and ''Hadrocodium''. The more advanced therapsids could have had a combination of naked skin, whiskers, and
scute A scute or scutum (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roma ...
s. A full pelage likely did not evolve until the therapsid-mammal transition. The more advanced, smaller therapsids could have had a combination of hair and scutes, a combination still found in some modern mammals, such as rodents and the opossum. The high interspecific variability of the size, color, and microstructure of hair often enables the identification of species based on single hair filaments. In varying degrees most
mammal Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republ ...
s have some skin areas without natural hair. On the human body, glabrous human skin, skin is found on the ventral portion of the fingers, hand, palms, sole (foot), 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: lamellar corpuscle, Pacinian corpuscles, tactile corpuscle, Meissner's corpuscles, Merkel nerve ending, Merkel's discs, and bulbous corpuscle, 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.


Human hairlessness

The general hairlessness of humans in comparison to related species may be due to loss of functionality in the pseudogene KRTHAP1 (which helps produce keratin) in the human lineage about 240,000 years ago. On an individual basis, mutations in the gene HR can lead to complete hair loss, though this is not typical in humans. Humans may also lose their hair as a result of hormonal imbalance due to drugs or pregnancy. In order to comprehend why humans have significantly less body hair than other primates, one must understand that mammalian body hair is not merely an aesthetic characteristic; it protects the skin from wounds, bites, heat, cold, and UV radiation. Additionally, it can be used as a communication tool and as a camouflage. Humans are the only primate species that have undergone significant hair loss and of the approximately 5000 extant species of mammal, only a handful are effectively hairless. This list includes elephants, rhinoceroses, hippopotamuses, walruses, some species of pigs, whales and other cetaceans, and naked mole rats. Most mammals have light skin that is covered by fur, and biologists believe that early human ancestors started out this way also. Dark skin probably evolved after humans lost their body fur, because the naked skin was vulnerable to the strong UV radiation as explained in the Out of Africa hypothesis. Therefore, evidence of the time when human skin darkened has been used to date the loss of human body hair, assuming that the dark skin was needed after the fur was gone. It was expected that dating the split of the ancestral human louse into two species, the head louse and the pubic louse, would date the loss of body hair in human ancestors. However, it turned out that the human pubic louse does not descend from the ancestral human louse, but from the gorilla louse, diverging 3.3 million years ago. This suggests that humans had lost body hair (but retained head hair) and developed thick pubic hair prior to this date, were living in or close to the forest where gorillas lived, and acquired pubic lice from butchering gorillas or sleeping in their nests. The evolution of the body louse from the head louse, on the other hand, places the date of clothing much later, some 100,000 years ago. The sweat glands in humans could have evolved to spread from the hands and feet as the body hair changed, or the hair change could have occurred to facilitate sweating. Horses and humans are two of the few animals capable of sweating on most of their body, yet horses are larger and still have fully developed fur. In humans, the skin hairs lie flat in hot conditions, as the arrector pili muscles relax, preventing heat from being trapped by a layer of still air between the hairs, and increasing heat loss by convection. Another hypothesis for the thick
body hair Body hair, or androgenic hair, is the terminal hair that develops on the human body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which is much finer and lighter in color. The growth of androgenic ...
on humans proposes that Fisherian runaway sexual selection played a role (as well as in the selection of long head hair), (see Terminal hair, terminal and
vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of g ...
), as well as a much larger role of testosterone in men. Sexual selection is the only theory thus far that explains the sexual dimorphism seen in the hair patterns of men and women. On average, men have more Androgenic hair, body hair than women. Males have more terminal hair, especially on the facial hair, face, chest hair, chest, abdominal hair, abdomen, and back, and females have more
vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of g ...
, which is less visible. The halting of hair development at a juvenile stage, vellus hair, would also be consistent with the neoteny evident in humans, especially in females, and thus they could have occurred at the same time. This theory, however, has significant holdings in today's cultural norms. There is no evidence that sexual selection would proceed to such a drastic extent over a million years ago when a full, lush coat of hair would most likely indicate health and would therefore be more likely to be selected ''for'', not against. A further hypothesis is that human hair was reduced in response to
ectoparasites Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...
. The "ectoparasite" explanation of modern human nakedness is based on the principle that a hairless primate would harbor fewer parasites. When our ancestors adopted group-dwelling social arrangements roughly 1.8 mya, ectoparasite loads increased dramatically. Early humans became the only one of the 193 primate species to have fleas, which can be attributed to the close living arrangements of large groups of individuals. While primate species have communal sleeping arrangements, these groups are always on the move and thus are less likely to harbor ectoparasites. Another view is proposed by James Giles (philosopher), James Giles, who attempts to explain hairlessness as evolved from the relationship between mother and child, and as a consequence of bipedalism. Giles also connects romantic love to hairlessness. Another hypothesis is that humans' use of fire caused or initiated the reduction in human hair.


Evolutionary variation

Evolutionary biologists suggest that the genus ''Homo'' arose in East Africa approximately 2.5 million years ago. They devised new hunting techniques. The higher protein diet led to the evolution of larger body and brain sizes. Jablonski postulates that increasing body size, in conjunction with intensified hunting during the day at the equator, gave rise to a greater need to rapidly expel heat. As a result, humans evolved the ability to sweat: a process which was facilitated by the loss of body hair. Another factor in human evolution that also occurred in the prehistoric past was a preferential selection for neoteny, particularly in females. The idea that adult humans exhibit certain neotenous (juvenile) features, not evinced in the other great apes, is about a century old. Louis Bolk made a long list of such traits, and Stephen Jay Gould published a short list in ''Ontogeny and Phylogeny (book), Ontogeny and Phylogeny''. In addition, paedomorphic characteristics in women are often Physical attractiveness#Determinants of female physical attractiveness, acknowledged as desirable by men in Psychology#Contemporary issues in methodology and practice, developed countries. For instance,
vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of g ...
is a juvenile characteristic. However, while men develop longer, coarser, thicker, and darker terminal hair through sexual differentiation, women do not, leaving their vellus hair visible.


Texture


Curly hair

Jablonski asserts head hair was evolutionarily advantageous for pre-humans to retain because it protected the scalp as they walked upright in the intense African (equatorial) UV light. While some might argue that, by this logic, humans should also express hairy shoulders because these body parts would putatively be exposed to similar conditions, the protection of the head, the seat of the brain that enabled humanity to become one of the most successful species on the planet (and which also is very vulnerable at birth) was arguably a more urgent issue (axillary hair in the underarms and groin were also retained as signs of sexual maturity). Sometime during the gradual process by which ''Homo erectus'' began a transition from furry skin to the naked skin expressed by Homo sapiens, hair texture putatively gradually changed from straight hair (the condition of most mammals, including humanity's closest cousins—chimpanzees) to Afro-textured hair or 'kinky' (i.e. tightly coiled). This argument assumes that curly hair better impedes the passage of UV light into the body relative to straight hair (thus curly or coiled hair would be particularly advantageous for light-skinned hominids living at the equator). It is substantiated by Iyengar's findings (1998) that UV light can enter into straight human hair roots (and thus into the body through the skin) via the hair shaft. Specifically, the results of that study suggest that this phenomenon resembles the passage of light through fiber optic tubes (which do not function as effectively when kinked or sharply curved or coiled). In this sense, when hominids (i.e. Homo Erectus) were gradually losing their straight body hair and thereby exposing the initially pale skin underneath their fur to the sun, straight hair would have been an adaptive liability. By inverse logic, later, as humans traveled farther from Africa and/or the equator, straight hair may have (initially) evolved to aid the entry of UV light into the body during the transition from dark, UV-protected skin to paler skin. Jablonski's assertions suggest that the adjective "woolly" in reference to Afro-hair is a misnomer in connoting the high heat insulation derivable from the true wool of sheep. Instead, the relatively sparse density of Afro-hair, combined with its springy coils actually results in an airy, almost sponge-like structure that in turn, Jablonski argues, more likely facilitates an increase in the circulation of cool air onto the scalp. Further, wet Afro-hair does not stick to the neck and scalp unless totally drenched and instead tends to retain its basic springy puffiness because it less easily responds to moisture and sweat than straight hair does. In this sense, the trait may enhance comfort levels in intense equatorial climates more than straight hair (which, on the other hand, tends to naturally fall over the ears and neck to a degree that provides slightly enhanced comfort levels in cold climates relative to tightly coiled hair). Further, it is notable that the most pervasive expression of this hair texture can be found in sub-Saharan Africa; a region of the world that abundant genetic and paleo-anthropological evidence suggests, was the relatively recent (≈200,000-year-old) point of origin for modern humanity. In fact, although genetic findings (Tishkoff, 2009) suggest that sub-Saharan Africans are the most genetically diverse continental group on Earth, Afro-textured hair approaches ubiquity in this region. This points to a strong, long-term selective pressure that, in stark contrast to most other regions of the genomes of sub-Saharan groups, left little room for genetic variation at the determining loci. Such a pattern, again, does not seem to support human sexual aesthetics as being the sole or primary cause of this distribution.


The EDAR locus

A group of studies have recently shown that genetic patterns at the EDAR locus, a region of the modern human genome that contributes to hair texture variation among most individuals of East Asian descent, support the hypothesis that (East Asian) straight hair likely developed in this branch of the modern human lineage subsequent to the original expression of tightly coiled natural afro-hair. Specifically, the relevant findings indicate that the EDAR mutation coding for the predominant East Asian 'coarse' or thick, straight hair texture arose within the past ≈65,000 years, which is a time frame that covers from the earliest of the 'Out of Africa' migrations up to now.


Disease

Tinea corporis, Ringworm is a mycosis, fungal disease that targets hairy skin. Premature greying of hair is another condition that results in greying before the age of 20 years in Whites, before 25 years in Asians, and before 30 years in Africans.


Hair care

Hair care involves the hygiene and cosmetology of hair including hair on the scalp, facial hair (beard and moustache), pubic hair and other body hair. Hair care routines differ according to an individual's culture and the physical characteristics of one's hair. Hair may be colored, trimmed, shaved, plucked, or otherwise removed with treatments such as waxing, sugaring, and threading.


Removal practices

Depilation is the removal of hair from the surface of the skin. This can be achieved through methods such as shaving. Epilation is the removal of the entire hair strand, including the part of the hair that has not yet left the follicle. A popular way to epilate hair is through waxing.


Shaving

Shaving is accomplished with bladed instruments, such as razors. The blade is brought close to the skin and stroked over the hair in the desired area to cut the terminal hairs and leave the skin feeling smooth. Depending upon the rate of growth, one can begin to feel the hair growing back within hours of shaving. This is especially evident in men who develop a five o'clock shadow after having shaved their faces. This new growth is called Shaving, stubble. Stubble typically appears to grow back thicker because the shaved hairs are blunted instead of tapered off at the end, although the hair never actually grows back thicker.


Waxing

Waxing involves using a sticky wax and strip of paper or cloth to pull hair from the root. Waxing is the ideal hair removal technique to keep an area hair-free for long periods of time. It can take three to five weeks for waxed hair to begin to resurface again. Hair in areas that have been waxed consistently is known to grow back finer and thinner, especially compared to hair that has been shaved with a razor.


Laser removal

Laser hair removal is a cosmetic method where a small laser beam pulses selective heat on dark target matter in the area that causes hair growth without harming the skin tissue. This process is repeated several times over the course of many months to a couple of years with hair regrowing less frequently until it finally stops; this is used as a more permanent solution to waxing or shaving. Laser removal is practiced in many clinics along with many at-home products.


Cutting and trimming

Because the hair on one's head is normally longer than other types of body hair, it is cut with scissors or Manual hair clippers, clippers. People with longer hair will most often use scissors to cut their hair, whereas shorter hair is maintained using a trimmer. Depending on the desired length and overall health of the hair, periods without cutting or trimming the hair can vary. Cut hair may be used in wigs. Global imports of hair in 2010 was worth $US 1.24 billion.


Social role

Hair has great social significance for human beings. It can grow on most external areas of the
human body The human body is the structure of a human being Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of ...

human body
, except on the palms of the hands and the soles of the feet (among other areas). Hair is most noticeable on most people in a small number of areas, which are also the ones that are most commonly trimmed, Plucking (hair removal), plucked, or shaving, shaved. These include the face, ears, human head, head, eyebrows, human leg, legs, and armpits, as well as the pubic region. The highly visible differences between male and female body and facial hair are a notable secondary sex characteristic. The world's longest documented hair belongs to Xie Qiuping (in China), at 5.627 m (18 ft 5.54 in) when measured on 8 May 2004. She has been growing her hair since 1973, from the age of 13.


Indication of status

Healthy hair indicates health and youth (important in evolutionary biology). Hair color and texture can be a sign of ethnic ancestry. Facial hair is a sign of puberty in men. White or gray hair is a sign of age or genetics, which may be concealed with Hair coloring, hair dye (not easily for some), although many prefer to assume it (especially if it is a poliosis characteristic of the person since childhood). Male pattern baldness is a sign of age, which may be concealed with a toupee, hats, or religious and cultural adornments. Although drugs and medical procedures exist for the treatment of baldness, many balding men simply shave their heads. In early modern China, the queue was a male hairstyle worn by the Manchus from central Manchuria and the Han Chinese during the Qing dynasty; hair on the front of the head was shaved off above the temples every ten days, mimicking male-pattern baldness, and the rest of the hair braided into a long pigtail. Hairstyle may be an indicator of group membership. During the English Civil War, the followers of Oliver Cromwell decided to crop their hair close to their head, as an act of defiance to the curls and ringlets of the king's men. This led to the Parliamentary faction being nicknamed Roundheads. Recent isotopic analysis of hair is helping to shed further light on sociocultural interaction, giving information on food procurement and consumption in the 19th century. Having Bob cut, bobbed hair was popular among the flappers in the 1920s as a sign of rebellion against traditional roles for women. Female art students known as the "cropheads" also adopted the style, notably at the Slade School in London, England. Regional variations in hirsutism cause practices regarding hair on the arms and legs to differ. Some religious groups may follow certain rules regarding hair as part of religious observance. The rules often differ for men and women. Many subcultures have hairstyles which may indicate an unofficial membership. Many hippies, Heavy metal subculture, metalheads, and Indian sadhus have long hair, as well many older Hipster (contemporary subculture), indie kids. Many punk fashion, punks wear a hairstyle known as a Mohawk hairstyle, mohawk or other spiked and dyed hairstyles; skinheads have short-cropped or completely shaved heads. Long stylized bangs were very common for Emo (stereotype), emos, Scene (subculture), scene kids and younger Hipster (contemporary subculture), indie kids in the 2000s and early 2010s, among people of both genders. Heads were shaved in concentration camps, and head-shaving has been used as punishment, especially for women with long hair. The shaven head is common in military haircuts, while Western monks are known for the tonsure. By contrast, among some Indian holy men, the hair is worn extremely long. In the time of Confucius (5th century BCE), the Chinese grew out their hair and often tied it, as a symbol of filial piety. Regular hairdressing in some cultures is considered a sign of wealth or status. The dreadlocks of the Rastafari movement were despised early in the movement's history. In some cultures, having one's hair cut can symbolize a liberation from one's past, usually after a trying time in one's life. Cutting the hair also may be a sign of mourning. Tightly coiled hair in its natural state may be worn in an Afro. This hairstyle was once worn among African Americans as a symbol of racial pride. Given that the coiled texture is the natural state of some African Americans' hair, or perceived as being more "African", this simple style is now often seen as a sign of self-acceptance and an affirmation that the beauty norms of the (Eurocentrism, eurocentric) dominant culture are not absolute. It is important to note that African Americans as a whole have a variety of hair textures, as they are not an ethnically homogeneous group, but an ad-hoc of different racial admixtures. The film ''Easy Rider'' (1969) includes the assumption that the two main characters could have their long hairs forcibly shaved with a rusty razor when jailed, symbolizing the intolerance of some conservative groups toward members of the counterculture. At the conclusion of the Oz trial, Oz obscenity trials in the UK in 1971, the defendants had their heads shaved by the police, causing public outcry. During the appeal trial, they appeared in the dock wearing wigs. A case where a 14-year-old student was expelled from school in Brazil in the mid-2000s, allegedly because of his fauxhawk haircut, sparked national debate and legal action resulting in compensation.


Religious practices

Women's hair may be hidden using headscarf, headscarves, a common part of the ''hijab'' in Islam and a symbol of modesty required for certain religious rituals in Eastern Orthodox Church, Eastern Orthodoxy. Russian Orthodox Church requires all married women to wear headscarves inside the church; this tradition is often extended to all women, regardless of marital status. Orthodox Judaism also commands the use of scarves and other head coverings for married women for modesty reasons. Certain Hindu sects also wear head scarves for religious reasons. Sikhism, Sikhs have an obligation not to cut hair (a Sikh cutting hair becomes 'apostate' which means fallen from religion) and men keep it tied in a bun on the head, which is then covered appropriately using a turban. Multiple religions, both ancient and contemporary, require or advise one to allow their hair to become dreadlocks, though people also wear them for fashion. For men, Islam, Orthodox Judaism, Orthodox Christianity, Roman Catholicism, and other religious groups have at various times recommended or required the covering of the head and sections of the hair of men, and some have dictates relating to the cutting of men's facial and head hair. Some Christian sects throughout history and up to modern times have also religiously proscribed the cutting of women's hair. For some Sunni madhabs, the donning of a kufi or Taqiyah (cap), topi is a form of sunnah.The War Within Our Hearts – Page 65 Sa'ad Quadri – 2013


See also

* Chaetophobia – the fear of hair * Hair analysis (alternative medicine) * Hypertrichosis – the state of having an excess of hair on the head or body * Hypotrichosis – the state of having a less than normal amount of hair on the head or body * Lanugo * Seta – hair-like structures in insects * Trichotillomania – hair pulling


References


Citations


Sources

* * * *


External links

* *
How to measure the diameter of your own hair using a laser pointerInstant insight
outlining the chemistry of hair from the Royal Society of Chemistry * {{Authority control Hair, Human hair,