Science Fair Project Encyclopedia
Red hair
Red hair is a hair color shared by several species, among them humans, orangutans and horses. Although red hair in the human population is most commonly associated with those of British or Irish descent, dark red or reddish-tinged hair can be found in many parts of the world—for instance, to a small degree, in Japan. Some believe that the cluster of red-heads in the British Isles can be associated with Pictish or Celtic ancestry and certainly Scotland has the highest proportion of red-heads of any country worldwide with 13% of the population having red hair. A further 40% of Scots carry the so-called "ginger gene". Ireland has the second highest red-headed population in the world amounting to 10% of its inhabitants.
It is estimated that between 2% and 5% of the United States population have red hair.
Red hair is significantly thicker than the hair of people of European descent with other hair colours. The numerical density of hairs on the head in red-heads is also lower.
In cases of severe malnutrition, normally dark human hair may turn red or blond. The condition, known as kwashiorkor, is a sign of critical starvation caused by protein deficiency, and is common during periods of famine.
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Biochemistry and genetics of red hair
The biochemistry of red hair appears to be associated with the melanocortin-1 receptor while the red colour itself is produced by an iron compound. The recessive gene which gives people red hair, fair skin and freckles is certainly older than 50,000 years, and it could be as old as 100,000 years. All red heads are MC1R variants, and the prevalence of these alleles is highest in Celtic Countries.
The genetics of red hair is now being uncovered, together with connections between red hair and melanoma and other skin disorders , and red hair and problems with anaesthesia.
There is evidence for genetic linkage of eye color with other hair colors such as brown hair, so it would not be surprising if red hair were linked with eye color inheritance.
Myths and stories about red-headed people
- "Red-headed people have fiery tempers"
- "Red-headed people are better lovers"
- The Biblical mark of Cain is supposed by some to be red hair.
- Ancient Romans considered redheads to be unlucky.
The Redhead Fetish
There are some people (male and female) who describe themselves as "redophiles." These people have a strong love for, and usually, are sexually attracted to redheads. As in any paraphilia, there are varying degrees to which a self-described redophile holds their desire. While some people favor the red hair solely for its aesthetic pleasantness, others are more passionate and insist on giving their attentions only to natural redheads because they possess certain desired physical features like pale skin that never tans, freckles, light pink areolas, and red pubic hair.
In addition to having appealing physical traits, redophiles perceive redheads as generally being more passionate than other people. Redophiles feel that having this in a partner is an additional spice to life that promises to always keep things interesting. Also, since redheads are such a small minority in the world, redophiles see redheads as a rare find.
See also
- Blonde
- Brunette
- List of famous redheads
- strawberry blonde
- auburn
- melanocytes
- melanin
- eumelanin
- phaeomelanin
- keratinocytes
- henna
- human skin color
External links
- Box NF, Wyeth JR, O'Gorman LE, Martin NG, Sturm RA. Characterization of melanocyte stimulating hormone receptor variant alleles in twins with red hair. Hum Mol Genet. 1997 Oct;6(11):1891-7.
- OMIM entry on red hair
- The roots of red hair
- Red Hair genetics for non-specialists
- Melanocortin 1 receptor: What’s red got to do with it?
- The Melanocortin 1 Receptor (MC1R): More Than Just Red Hair
- Why is red hair with brown eyes so uncommon?
- Distribution of hair and eye color and sex in 592 statistics students. from Snee, R. D. (1974). Graphical display of two-way contingency tables. The American Statistician, 28, 9-12. (displayed as a table)
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