Changes

‘’’Red hair‘’ (or ‘’’ginger hair’’’) occurs naturally in two percent of the overall planet earth, human population, appearing in higher percentages (two to six percent) among people of Northern or Northwestern European ancestry and lesser frequency in other human populations. So for the most part, gingers are a rare breed, far outnumbered by the yellow and brown haired members of the human species.

‘’’Red hair‘’ (or ‘’’ginger hair’’’) occurs naturally in two percent of the overall planet earth, human population, appearing in higher percentages (two to six percent) among people of Northern or Northwestern European ancestry and lesser frequency in other human populations. So for the most part, gingers are a rare breed, far outnumbered by the yellow and brown haired members of the human species.

It is most common in individuals homozygous for a recessive allele on chromosome 16 that produces an altered version of the  melanocortin 1 receptor (MC1R) protein. The melanocortin 1 receptor (MC1R) plays important roles in human basal pigmentation and UVR-induced tanning response. The human MC1R locus is highly polymorphic, which results in the diversity of skin pigmentation levels.

It is most common in individuals homozygous for a recessive allele on chromosome 16 that produces an altered version of the  melanocortin 1 receptor (MC1R) protein. The melanocortin 1 receptor (MC1R) plays important roles in human basal pigmentation and UVR-induced tanning response. The human MC1R locus is highly polymorphic, which results in the diversity of skin pigmentation levels.

Red hair varies in hue from a deep burgundy or bright copper, or auburn, to burnt orange or red-orange to strawberry blond. Characterized by high levels of the reddish pigment pheomelanin and relatively low levels of the dark pigment eumelanin, it is associated with fair skin color, lighter eye color, freckles, and sensitivity to ultraviolet light.

Red hair varies in hue from a deep burgundy or bright copper, or auburn, to burnt orange or red-orange to strawberry blond. Characterized by high levels of the reddish pigment pheomelanin and relatively low levels of the dark pigment eumelanin, it is associated with fair skin color, lighter eye color, freckles, and sensitivity to [[ultraviolet]] light.

Cultural reactions to red hair have varied from ridicule to admiration with many common stereotypes in existence regarding redheads. The term redhead has been in use since at least 1510.

Cultural reactions to red hair have varied from ridicule to admiration with many common stereotypes in existence regarding redheads. The term redhead has been in use since at least 1510.

==Genetic Mutation==

==Genetic Mutation==

Red hair is associated with fair skin color because low concentrations of eumelanin throughout the body of those with red hair caused by a MC1R mutation can cause both. The lower melanin concentration in skin confers the advantage that a sufficient concentration of important Vitamin D can be produced under low light conditions. However, when UV-radiation is strong (as in regions close to the equator) the lower concentration of melanin leads to several medical disadvantages, such as a higher risk of skin cancer. The MC1R variant gene that gives people red hair generally results in skin that is difficult or impossible to sun tan. Because of the natural tanning reaction to the sun's ultraviolet light and high amounts of pheomelanin in the skin, freckles are a common but not universal feature of red-haired people.

Red hair is associated with fair skin color because low concentrations of eumelanin throughout the body of those with red hair caused by a MC1R mutation can cause both. The lower melanin concentration in skin confers the advantage that a sufficient concentration of important Vitamin D can be produced under low light conditions. However, when UV-radiation is strong (as in regions close to the equator) the lower concentration of melanin leads to several medical disadvantages, such as a higher risk of skin cancer. The MC1R variant gene that gives people red hair generally results in skin that is difficult or impossible to sun tan. Because of the natural tanning reaction to the sun's ultraviolet light and high amounts of pheomelanin in the skin, freckles are a common but not universal feature of red-haired people.

Red hair can originate from several changes on the MC1R-gene. If one of these changes is present on both chromosomes then the respective individual is likely to have red hair. This type of inheritance is described as an autosomal [[recessive gene|recessive]]. Even if both parents do not have red hair themselves, both can be Genetic carriers for the gene and have a redheaded child.

Red hair can originate from several changes on the MC1R-gene. If one of these changes is present on both chromosomes then the respective individual is likely to have red hair. This type of inheritance is described as an autosomal [[recessive gene|recessive]]. Even if both parents do not have red hair themselves, both can be Genetic carriers for the gene and have a redheaded child.

Genetic studies of dizygotic (fraternal) twins indicate that the MC1R gene is not solely responsible for the red hair phenotype; unidentified modifier genes exist, making variance in the MC1R gene necessary, but not sufficient, for red hair production.

Genetic studies of dizygotic (fraternal) twins indicate that the MC1R gene is not solely responsible for the red hair phenotype; unidentified modifier genes exist, making variance in the MC1R gene necessary, but not sufficient, for red hair production. Additionally Red hair doesn’t gray as much as other hair colors. Red hair initially tends to turn blond and then white.

=== Genetics ===

=== Genetics ===

[[File: Redhead_close_up.jpg|thumb| A close-up view of red hair]]

[[File: Redhead_close_up.jpg|thumb| A close-up view of red hair]]

Researchers have found that people with red hair require greater amounts of anesthetic. Other research publications have concluded that women with naturally red hair require less of the painkiller pentazocine than do either women of other hair colors or men of any hair color. A study showed women with red hair had a greater analgesic response to that particular pain medication than men. A follow-up study by the same group showed that men and women with red hair had a greater analgesic response to morphine-6-glucuronide.

Researchers have found that people with red hair require greater amounts of anesthetic. Other research publications have concluded that women with naturally red hair require less of the painkiller pentazocine than do either women of other hair colors or men of any hair color. A study showed women with red hair had a greater analgesic response to that particular pain medication than men. A follow-up study by the same group showed that men and women with red hair had a greater analgesic response to morphine-6-glucuronide.

The unexpected relationship of hair color to pain tolerance appears to exist because redheads have a mutation in a hormone receptor that can apparently respond to at least two types of hormones: the pigmentation-driving melanocyte-stimulating hormone (MSH), and the pain-relieving endorphins. (Both derive from the same precursor molecule, POMC, and are structurally similar.) Specifically, redheads have a mutated melanocortin-1 receptor (MC1R) gene that produces an altered receptor for MSH. Melanocytes, the cells that produce pigment in skin and hair, use the MC1R to recognize and respond to MSH from the anterior [[pituitary gland]]. Melanocyte-stimulating hormone normally stimulates melanocytes to make black eumelanin, but if the melanocytes have a mutated receptor, they will make reddish pheomelanin instead. MC1R also occurs in the brain, where it is one of a large set of POMC-related receptors that are apparently involved not only in responding to MSH, but also in responses to endorphins and possibly other POMC-derived hormones. Though the details are not clearly understood, it appears that there is some crosstalk between the POMC hormones; this may explain the link between red hair and pain tolerance.

The unexpected relationship of hair color to pain tolerance appears to exist because redheads have a mutation in a hormone receptor that can apparently respond to at least two types of hormones: the pigmentation-driving melanocyte-stimulating hormone (MSH), and the pain-relieving endorphins. (Both derive from the same precursor molecule, POMC, and are structurally similar.) Specifically, redheads have a mutated melanocortin-1 receptor (MC1R) gene that produces an altered receptor for MSH. Melanocytes, the cells that produce pigment in skin and hair, use the MC1R to recognize and respond to MSH from the anterior [[pituitary gland]]. Melanocyte-stimulating hormone normally stimulates melanocytes to make black eumelanin, but if the melanocytes have a mutated receptor, they will make reddish pheomelanin instead. MC1R also occurs in the brain, where it is one of a large set of POMC-related receptors that are apparently involved not only in responding to MSH, but also in responses to endorphins and possibly other POMC-derived hormones. Though the details are not clearly understood, it appears that there is some crosstalk between the POMC hormones; this may explain the link between red hair and pain tolerance.

There is little or no evidence to support the belief that people with red hair have a higher chance than people with other hair colors to hemorrhage or suffer other bleeding complications. One study, however, reports a link between red hair and a higher rate of bruising.

There is little or no evidence to support the belief that people with red hair have a higher chance than people with other hair colors to hemorrhage or suffer other bleeding complications. One study, however, reports a link between red hair and a higher rate of bruising. Redheaded women report bruising more easily than other women of different hair colors.

== Red hair of pathological origin ==

== Red hair of pathological origin ==

Most red hair is caused by the MC1R gene and is non-pathological. However, in rare cases red hair can be associated with disease or genetic disorder:

Most red hair is caused by the MC1R gene and is non-pathological. However, in rare cases red hair can be associated with disease or genetic disorder:

A common belief about redheads is that they have fiery tempers and sharp tongues. In ''[[Anne of Green Gables]]'', a character says of Anne Shirley, the redheaded heroine, that "her temper matches her hair", while in ''[[The Catcher in the Rye]]'', Holden Caulfield remarks that "People with red hair are supposed to get mad very easily, but Allie [his dead brother] never did, and he had very red hair."

A common belief about redheads is that they have fiery tempers and sharp tongues. In ''[[Anne of Green Gables]]'', a character says of Anne Shirley, the redheaded heroine, that "her temper matches her hair", while in ''[[The Catcher in the Rye]]'', Holden Caulfield remarks that "People with red hair are supposed to get mad very easily, but Allie [his dead brother] never did, and he had very red hair."

During the early stages of modern medicine, red hair was thought to be a sign of a sanguine temperament. In the Indian medicinal practice of Ayurveda, redheads are seen as most likely to have a Pitta temperament.

According to Hamburg sex researcher Dr. Werner Habermehl, women with red hair have more sex than blondes or brunette women or women with other hair colors. He also postulates that women in a relationship who dye their hair red may be signaling that they are unhappy and looking for something better. During the early stages of modern medicine, red hair was thought to be a sign of a sanguine temperament. In the Indian medicinal practice of Ayurveda, redheads are seen as most likely to have a Pitta temperament.

Another belief is that redheads are highly sexed; for example, [[Jonathan Swift]] satirizes redhead stereotypes in part four of ''[[Gulliver's Travels]]'', "A Voyage to the Country of the Houyhnhnms," when he writes that: "It is observed that the red-haired of both sexes are more libidinous and mischievous than the rest, whom yet they much exceed in strength and activity." Swift goes on to write that "neither was the hair of this brute [a Yahoo] of a red color (which might have been some excuse for an appetite a little irregular) but black as a sloe". Such beliefs were given a veneer of scientific credibility in the 19th century by Cesare Lombroso and Guglielmo Ferrero. They concluded that red hair was associated with crimes of lust, and claimed that forty eight percent of "criminal women" were redheads.

Another belief is that redheads are highly sexed; for example, [[Jonathan Swift]] satirizes redhead stereotypes in part four of ''[[Gulliver's Travels]]'', "A Voyage to the Country of the Houyhnhnms," when he writes that: "It is observed that the red-haired of both sexes are more libidinous and mischievous than the rest, whom yet they much exceed in strength and activity." Swift goes on to write that "neither was the hair of this brute [a Yahoo] of a red color (which might have been some excuse for an appetite a little irregular) but black as a sloe". Such beliefs were given a veneer of scientific credibility in the 19th century by Cesare Lombroso and Guglielmo Ferrero. They concluded that red hair was associated with crimes of lust, and claimed that forty eight percent of "criminal women" were redheads.

=== Media, fashion and art ===

=== Media, fashion and art ===

==See also==

==See also==

*[[skin color]]

*[[skin color]]

[[Category:Biology]]

[[Category:Biology]]

[[Category:Anatomy]]

[[Category:Anatomy]]