Red hair appears most commonly in people with two copies of a recessive allele on chromosome 16 which produces an altered version of the MC1R protein. Red hair varies in hues from a deep burgundy or bright copper reddish-brown or auburn through to burnt orange or red-orange and strawberry blond.
It is characterized by high levels of the reddish pigment pheomelanin and relatively low levels of the dark pigment eumelanin. It is Redhead makign out with fair skin colorlighter eye colors gray, blue, green, and hazelfrecklesand sensitivity to ultraviolet light. Cultural reactions have varied from ridicule to admiration; many common stereotypes exist regarding redheads and they are often portrayed as fiery-tempered.
The term redhead has been in use since Redhead makign out least Red hair is most commonly found at the northern and western fringes of Europe ;  it is centered around populations in the British Isles. Redheads today are commonly associated with the Celtic nations  and to a far lesser extent the Germanic peoples.
According to Britain's DNA, Carleton Coon's book The Races of Europe stated that rufosity reddish hair often occurred in Montenegrins. In Italyred hair is found at a frequency of 0. The Berber populations of Morocco  and northern Algeria have occasional redheads.
Red hair frequency is especially significant among the Riffians from Redhead makign out and Kabyles from Algeria,    respectively. Abd ar-Rahman I also had red hair, his mother being a Christian Berber slave. Red hair is also found amongst the Ashkenazi Jewish populations. The use of henna on hair and skin for various reasons occasionally occurs in Asia.
When henna is used on hair it dyes the hair to different shades of red. This would give the U. Several accounts by Greek writers mention redheaded people. A fragment by the poet Xenophanes describes the Thracians as blue-eyed and red-haired.
In Asia, red hair has been found among the ancient Tocharianswho occupied the Tarim Basin in what is now the northwesternmost province of China.
Caucasian Tarim mummies have been found with red hair dating to the 2nd millennium BC. Reddish-brown auburn hair is also found amongst some Polynesiansand is especially common in some tribes and family groups. In Polynesian culture reddish hair has traditionally been seen as a sign of descent from high-ranking ancestors and a mark of rulership.
The pigment pheomelanin gives red hair its distinctive color. Red hair has far more of the pigment pheomelanin than it has of the dark pigment eumelanin.
The genetics of red hair, discovered inappear to be associated with the melanocortin-1 receptor MC1Rwhich is found on chromosome 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 Redhead makign out 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 recessive variant gene that gives people red hair generally results in skin that is unable to tan.
Because of the natural tanning reaction to the sun's ultraviolet light and Redhead makign out amounts of pheomelanin in the skin, freckles are a common but not all-inclusive feature of red-haired people.
Eighty percent of redheads have an MC1R gene variant. 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 mode of inheritance. Even if both parents do not have red hair themselves, both can be 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 always sufficient, for red hair production.
Red hair is the rarest natural hair color in humans. The non-tanning skin associated with red hair may have been advantageous in far-northern climates where sunlight is scarce. Studies by Bodmer and Cavalli-Sforza hypothesized that lighter skin pigmentation prevents rickets in colder climates by encouraging higher levels of vitamin D production and also allows the individual to retain heat better than Redhead makign out with darker skin.
In Africa, for example, red hair is selected against because high levels Redhead makign out sun harm untanned skin. However, in Northern Europe this does not happen, so redheads can become more common through genetic drift.
Estimates on the original occurrence of the currently active gene for red hair vary from 20, toyears ago. A DNA study has concluded that some Neanderthals also had red hair, although the mutation responsible for this differs from that which causes red hair in modern humans. A report in The Courier-Mailwhich cited the National Geographic magazine and unnamed "geneticists", said that red hair is likely to die out in the near future.
The National Geographic article in fact states "while redheads may decline, the potential for red isn't going away". Red hair is caused by a relatively rare recessive allele variant of a genethe expression of which can skip generations. It is not likely to Redhead makign out at any time Redhead makign out the foreseeable future. Melanin in the skin aids UV tolerance through suntanningbut fair-skinned persons lack the levels of melanin needed to Redhead makign out UV-induced DNA-damage.
Studies have shown that red hair alleles in MC1R increase freckling and decrease tanning ability. Red hair and its relationship to UV sensitivity are of interest to many melanoma researchers. Redhead makign out can both Redhead makign out good and bad for a person's health and the different alleles on MC1R represent these adaptations. It also has been shown that individuals with pale skin are highly susceptible to a variety of skin cancers such as melanomabasal cell carcinomaand squamous cell carcinoma.
Two studies have demonstrated that people with red hair have different sensitivity to pain compared to people with other hair colors.