Red hair, often called ginger hair, is a captivating human hair color that has intrigued and sometimes mystified societies throughout history. Found in approximately 2-6% of people with Northern or Northwestern European ancestry, and less frequently in other populations, red hair boasts a spectrum of shades, from deep burgundy and bright copper to auburn, burnt orange, red-orange, and strawberry blond. This article delves into the fascinating world of red hair, exploring its genetic origins, cultural perceptions, unique characteristics, and associated health considerations.
The distinctive color of red hair stems from the pigment pheomelanin. The science behind red hair is associated with the melanocortin-1 receptor (MC1R) gene, located on chromosome 16. In 1995, researchers identified alleles on MC1R that are associated with red hair. These variants are now identified as RHC (red hair color) alleles. Eighty percent of redheads have an MC1R gene variant within the RHC.
The MC1R gene provides the code for a protein called melanocortin 1 receptor that is located on melanocytes and is responsible for the type of melanin produced. When the receptor is activated or turned on, melanocytes produce eumelanin. In contrast, if the receptor is not activated the melanocytes produce pheomelanin. Variations in the MC1R gene are responsible for this deactivation.
Red hair is also associated with fair skin because the MC1R mutation also results in low concentrations of eumelanin throughout the body. 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 tan.
It's important to note that while MC1R gene sequence variants have been found in over 80% of redheads and/or people with fair skin that does not tan, this may not be the complete story. A 2018 study of more than 343,000 UK Biobank participants found that MC1R accounts for only 73% of the genetic heritability of hair color. The authors reported that although 93% of people with red hair carry two MC1R variants, this corresponds to only 15% of people with two MC1R variants and that in fact, two MC1R variants are most often associated with blonde or light brown hair. The authors went on to identify eight additional variants associated with red hair including a variant in an intron of RALY that influences the expression of ASIP in the skin (expression controls whether a gene is turned on or off). An earlier study in Northern Europeans previously identified the role of a variant in ASIP in red hair and the authors of the 2018 study surmised that variants that increase ASIP expression in skin or hair follicles cause increased pheomelanin in melanocytes. They also found evidence of epistatic interactions (these are interactions between two or more genes which modify the effect of one gene) as some genes control when MC1R is switched on or off. This suggests that the genetics of red hair is more complicated than it first appears. It is also interesting to note that the authors of the 2018 study found a variant in HERC2 associated with a decreased probability of red hair.
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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. The genes responsible for red hair can express themselves to different extents in different people. One consequence of this is that a number of people have both dark hair and red beards. This may reflect the presence of a single copy of the MC1R gene, leading to differential expression in the beard versus the scalp hair.
The inheritance of red hair follows an autosomal recessive pattern. This means that two copies of the recessive MC1R gene variant (one inherited from each parent) are required for a child to have red hair. If both parents are redheads, their offspring will also have red hair. If one parent has red hair and the other is a carrier of the recessive gene, there is a 50% chance that their child will inherit red hair. If both parents are non-redheads but carry the recessive gene, there is a 25% chance of having a child with red hair.
Red hair is the rarest natural hair color in humans, with only 2% of the world population having red hair. Scotland, at 13%, has the highest population of gingers with Ireland runner-up at 10%. I live in Scotland, the redhead capital of the world. I have Scottish and Irish ancestry, so I guess I was pre-destined to have red hair (as well as freckles and a drawer full of SPF 100 sunscreen). Over the years I’ve gone from neon ginger to ‘sorta’ auburn ginger and at times I’ve succumbed to societal pressure and had blonde highlights.
While red hair is most prevalent in Northern and Northwestern Europe, it can be found in other populations around the world. The Berber populations of Morocco and northern Algeria have occasional redheads. Ancient human remains described as having red or auburn hair have been discovered in various parts of Asia, including the Tarim mummies of Xinjiang, China. In Chinese sources, ancient Kyrgyz people were described as fair-skinned, green- or blue-eyed and red-haired people with a mixture of European and East Asian features. Reddish-brown (auburn) hair is also found among some Polynesians, and is especially common in some tribes and family groups.
Besides their striking hair color, redheads often share other unique characteristics:
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Cultural reactions to red hair have been varied throughout history.
Many painters have exhibited a fascination with red hair. The hair color "Titian" takes its name from the artist Titian, who often painted women with red hair. Early Renaissance artist Sandro Botticelli's famous painting The Birth of Venus depicts the mythological goddess Venus as a redhead. Sir Arthur Conan Doyle's Sherlock Holmes story "The Red-Headed League" (1891) involves a man who is asked to become a member of a mysterious group of red-headed people.
Redhead Day festival in the Netherlands attracts red-haired participants from around the world. The Irish Redhead Convention, held in late August in County Cork since 2011, claims to be a global celebration and attracts people from several continents. The first and only festival for red heads in the United States was launched in 2015.
As well as their standout hair color, redheads seem to be more likely as a group to develop certain health conditions and have certain health risks. The MC1R variant gene that gives people red hair generally results in skin that is difficult or impossible to tan. Sunshine can both be good and bad for a person's health and the different alleles on MC1R represent these adaptations.
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