Celebs like Rihanna and Emma Stone may be making a style statement with red hair today, but flame-coloured locks are anything but a recent trend.

In fact, the first reported instances of red hair can be traced back as far as the Paleolithic age. Today, it remains a shade associated with passion, a fiery temper and rebellion. From coppers to strawberry blondes and fire-engine reds, the variety and many shades of this illustrious colour make it one of the most sought-after in salons around the world. But while it’s easy enough to turn tresses red artificially, real red hair is actually very rare, occurring in just 1-2% of the world’s population naturally. So where exactly does this vibrant colour come from, and why is it such a rarity?

The Ethnic Origins Behind Red Hair

Red hair can be traced as far back as 25,000 years ago, with the first suspected instances found in Neanderthal hunter-gatherers during late Stone Age.

Scientists and historians have suggested that during this time, the gene responsible for causing red hair was likely passed to Homo Sapiens via the Halpogroup R1b, while others maintain that the gene developed independently in this lineage and was not inherited. As this was a time of migration, exploration and hunting, the gene moved across the world, with naturally-occurring red hair now being a primarily European phenomenon.

Today, the highest instances occur in Scotland, Ireland and Wales, and this has been the case for hundreds of years, as both Roman and Greek literature denotes encounters with red heads in Britain. Many stereotypes surrounding red heads, such as a fiery temper and heightened sensitivity to pain can be attributed to some of this early literature, and are still propagated today.

Famous figures in history and literature including Boadicea and Helen of Troy were described as being red heads, but the term itself didn’t enter the Oxford English Dictionary until some time around 1511. Romans also described the Germanic people as having red hair. While there are instances of red hair occurring elsewhere in the world, it is primarily found in Europe, particularly in Celtic countries according to this map. The reasons it remains strong in Celtic countries can perhaps be attributed to things like the environment (more on that later), but the reason red hair exists at all is purely down to genetics.

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The Science Behind Red Hair

Scientifically speaking, red hair is caused by a genetic mutation.

The gene that causes red hair to occur is a recessive gene, meaning it must be present twice for red hair to form, or in other words, inherited from both parents. The MC1R gene, or melanocortin 1 receptor, is what causes the colour to develop, a mutated gene located on chromosone 16. The colour itself is characterised by high levels of the pigment pheomelanin (light in colour), and low levels of the pigment eumelanin (black/brown in colour). This balance also affects skin colour, and as such many individuals with red hair also have a fair skin tone.

Scientists suggest that the mutation may have occurred to help habitants of northern countries such as Scotland adapt to their surroundings. Lighter skin absorbs the vitamin D found even in small amounts of sunlight better than darker skin, which in turn boost the production of vitamin D in the body. For places such as Scotland that have rainy climates with little sun, having pale skin is hugely beneficial, the drawback being of course a propensity to burn even in low levels of sun and an increased risk of melanoma.

Because the gene is recessive, the chances of both parents having it are slim, even in countries with a high percentage of red heads. For example, approximately 13% of the Scottish population has red hair, yet almost 40% carry the gene. So could you carry the illusive MC1R gene? There are now DNA tests available to help you determine whether or not red hair runs in your family, and if you can expect a flame haired baby in the future!