Red hair varies from a deep burgundy through burnt orange to bright copper. Worldwide, is the rarest natural colour amongst humans. Only one in 200 people - approximately 1-2% of the human population - are redheads. Scotland has the highest proportion; 13% of the population has red hair and approximately 40% carries the recessive redhead gene. Ireland has the second highest percentage; as many as 10% of the Irish population has red, auburn, or strawberry blond hair. It is thought that up to 46% of the Irish population carries the recessive redhead gene.
Skin and hair colour are determined by a pigment known as melanin. There are two main categories; eumelanin which is brown-black and phaeomelanin which is a sort of reddish brown. A person with red hair will have much greater amounts of phaeomelanin than they will have of eumelanin. So what determines the difference?
The answers came to scientists in the late 1990’s. The focus of their studies was chromosome 16 and in particular one of its genes, MC1R. Now the job of MC1R is to make a protein called MC1R receptor (melanocortin 1). This protein plays a key role in the conversion of phaeomelanin to eumelanin. When there are two mutated versions of the MC1R gene, the conversions are not as frequent and so there is a build up of phaeomelanin in the pigment cells. Consequently a person will have red hair and fair skin. They are also prone to freckles.
To understand why this happens we need to cover some basic genetics. You inherit two copies of every gene from your parents, one from your mother and one from your father. So you have two copies of the MC1R gene. If both are mutated in the same way, the respective individual is likely to have red hair.
Of course many people wonder how a child with red hair can be born to parents who are brunette or blonde. That too can be explained by simple genetics, and a pattern of inheritance known as autosomal recessive.
The parents will both have a functioning and a mutant version of the MC1R gene. They are said to be carriers and there is a 1 in 4 chance of them having a child who is a redhead. That’s the probability that the mutant versions from both parents will come together in the next generation. It doesn’t of course mean that if a couple have four kids, one of them will have a child with ginger hair. Odds and probabilities do not work like that. They are not reliant on what went before. It means that each child has a 25% chance of having red hair. Because it’s a recessive trait, red hair can easily skip generations.
There is much more to this subject than its curiosity factor. There appear to be medical implications for people with red hair. Although here, like many areas of science, the research is contradictory. In 2002 researchers from Louisville University showed that redheads are more sensitive to pain, and need more anaesthetic during surgery than people with blonde or dark hair. However, in 2005 scientists from the University of Edinburgh found that a MC1R mutation gives redheads a higher tolerance for pain. Research into these aspects of red hair genetics continues.
Redheads should though be more careful about their exposure to sunlight as they are at an increased risk of contracting skin cancer. One theory suggests that melanin, the pigment responsible for tanning (it darkens as a protective mechanism) may be chemically different from the melanin of people with dark hair. Researchers have found that UV rays interact with phaeomelanin, creating molecules that cause damage to DNA, which can lead to cancer.
If you are a redhead, the advice is not to stay out of the sun, but to be careful about how much exposure you get, and to cover yourself with a high factor sunscreen.
Are redheads going extinct?
The story of redhead extinction has gone around the Internet before, most recently in 2005, with news articles citing the Oxford Hair Foundation as a source. These articles work on the mistaken assumption that recessive genes - like the one for red hair - can “die out”. Recessive genes can become rare but don’t disappear completely unless everyone carrying that gene dies or fails to reproduce. So while red hair may remain rare, enough people carry the gene that, barring global catastrophe, redheads should continue to appear for some time.
Some of the articles discussing redhead extinction referred to the Oxford Hair Foundation as an “independent” institute or research foundation, but a Google search shows that the Oxford Hair Foundation is funded by Proctor & Gamble, makers of numerous beauty products - including red hair dye.
In the most recent wave of redhead extinction warnings, some news outlets incorrectly cited the September 2007 issue of National Geographic as the source of the extinction claims. In fact, the National Geographic story provided some data about red hair in the world population, but it only said that “news reports” have claimed that redheads were going extinct. The piece did not explicitly back the claim. Instead, the article stated that “while redheads may decline, the potential for red isn’t going away”. Unfortunately the misconception about disappearing redheads is now widespread.
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