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What your hair reveals about your health
While on this program you will teach your body to live off its own fat reserves. So, what I can do for hormonal balance if my menstrual cycle is regular? As in, the hair can never regrow? The most perfect treatment cannot start to work any sooner than 3 months, and it may take more than a year. Do Not Send Email Notifications.

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The Pill, Thyroid, and 4 Other Types of Hormonal Hair Loss

This process is formally called piloerection , derived from the Latin words 'pilus' 'hair' and 'erectio' 'rising up' , but is more commonly known as 'having goose bumps ' in English. 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.

In some mammals, such as hedgehogs and porcupines , 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.

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. The eyebrows provide moderate protection to the eyes from dirt , sweat and rain.

They also play a key role in non-verbal 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 grows at the edges of the eyelid and protects the eye from dirt.

The eyelash is to humans, camels, horses, ostriches etc. Hair has its origins in the common ancestor of mammals, the synapsids , about million years ago. It is currently unknown at what stage the synapsids acquired mammalian characteristics such as body hair and mammary glands , as the fossils only rarely provide direct evidence for soft tissues. Skin impression of the belly and lower tail of a pelycosaur , possibly Haptodus shows the basal synapsid stock bore transverse rows of rectangular scutes , similar to those of a modern crocodile.

The oldest undisputed known fossils showing unambiguous imprints of hair are the Callovian late middle Jurassic Castorocauda and several contemporary haramiyidans , both near-mammal cynodonts. Some modern mammals have a special gland in front of each orbit used to preen the fur, called the harderian gland.

Imprints of this structure are found in the skull of the small early mammals like Morganucodon , but not in their 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 chapter of the brain that expanded markedly in animals like Morganucodon and Hadrocodium. A full pelage likely did not evolve until the therapsid-mammal transition.

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, [29] as are the labia minora and glans penis. 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.

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 , years ago. In order to comprehend why humans are essentially hairless, it is essential to understand that mammalian body hair is not merely an aesthetic characteristic; it protects the skin from wounds, bites, heat, cold, and UV radiation.

Humans are the only primate species that have undergone significant hair loss and of the approximately 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.

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.

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 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 on humans proposes that Fisherian runaway sexual selection played a role as well as in the selection of long head hair , see types of hair and vellus hair , 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 body hair than women. Males have more terminal hair , especially on the face , chest , abdomen , and back, and females have more vellus hair , 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. 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, and not all human populations today have sexual dimorphism in body hair.

A further hypothesis is that human hair was reduced in response to ectoparasites. When our ancestors adopted group-dwelling social arrangements roughly 1. Early humans became the only one of the 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.

Because of this, selection pressure for early humans would favor decreasing body hair because those with thick coats would have more lethal-disease-carrying ectoparasites and would thereby have lower fitness. Another view is proposed by 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 biologists suggest that the genus Homo arose in East Africa approximately 2.

As a result, humans evolved the ability to sweat: The female-male size differential among other closely associated primates is much greater than among humans, and therefore it was reduced during human evolution. Other primates have sweat gland in their armpits that function as those of humans, and thus it is probable that human sweat glands evolved from a similar distribution, spreading to more areas of the body, rather than occurring through evolution of a new trait.

It is not known whether the increased distribution of sweat glands occurred before, during, or after, the change in body hair, or even whether the two are related developments. Horses also sweat, and they are larger, hairier, and expend more energy running than human males, so there may not be any connection between the ability to sweat and the apparent hairlessness of humans. 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 great apes, is about a century old. Louis Bolk made a long list of such traits, [47] and Stephen Jay Gould published a short list in Ontogeny and Phylogeny.

However, while men develop longer, coarser, thicker, and darker terminal hair through sexual differentiation , women do not, leaving their vellus hair visible. Jablonski [46] 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 [ citation needed ] the condition of most mammals, including humanity's closest cousins—chimpanzees to Afro-textured hair or 'kinky' i. 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 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. 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. However, such anthropologists as Nina Jablonski oppositely argue about this hair texture. Specifically, Jablonski's assertions [46] 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, [46] 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, some [ who? Hence, they argue in favor of his suggestion that sexual selection may be responsible for such traits. However, inclinations towards deeming hair texture "adaptively trivial" may root in certain cultural value judgments more than objective logic. In this sense the possibility that hair texture may have played an adaptively significant role cannot be completely eliminated from consideration. In fact, while the sexual selection hypothesis cannot be ruled out, the asymmetrical distribution of this trait vouches for environmental influence.

Specifically, if hair texture were simply the result of adaptively arbitrary human aesthetic preferences, one would expect that the global distribution of the various hair textures would be fairly random.

Instead, the distribution of Afro-hair is strongly skewed toward the equator. In fact, although genetic findings Tishkoff, 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. 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.

Ringworm is a 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 involves the hygiene and cosmetology of hair including hair on the scalp , facial, pubic 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. 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 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 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 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 six weeks for waxed hair to begin to resurface again. Hair in areas that have previously been waxed also is known to grow back finer and thinner, especially compared to hair that has been shaved with a razor. 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. Because the hair on the head is normally longer than other types of body hair, it is cut with scissors or 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. Hair has great social significance for human beings. Hair is most noticeable on most people in a small number of areas, which are also the ones that are most commonly trimmed, plucked , or shaved.

These include the face , ears , head , eyebrows, 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 China , at 5.

She has been growing her hair since , from the age of 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 hair is a sign of age or genetics, which may be concealed with 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. 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.

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 , metalheads and Indian sadhus have long hair , as well many older indie kids. Many punks wear a hairstyle known as a mohawk or other spiked and dyed hairstyles; skinheads have short-cropped or completely shaved heads. Long stylized bangs were very common for emos , scene kids and younger indie kids in the s and early s, 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 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 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 obscenity trials in the UK in , the defendants had their heads shaved by the police, causing public outcry.

During the appeal trial, they appeared in the dock wearing wigs. Women's hair may be hidden using headscarves , a common part of the hijab in Islam and a symbol of modesty required for certain religious rituals in 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. Sikhs have an obligation not to cut hair a Sikh cutting hair becomes 'apostate' which means fallen from religion [64] 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.

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