The origin of red hair: a true rarity

Although red hair is trending among women and more and more people choose to dye their hair red, very few people in the world have naturally red hair. Only about 1-2% of the world's population can count themselves proud owners of a fiery head of hair. For comparison, over 95% of the world's population has dark to black hair. This rare occurrence of red hair makes it the rarest hair color of all. But why is that, actually, and what does it have to do with the origin of red hair?

origin of red hair

The Origin of Red Hair - From Genes to Hair Color

A person's hair color is fundamentally determined by genetics and can only be changed by coloring the hair externally. Many different genes are involved in hair coloring, and the MC1R gene, which sits on chromosome 16, is of particular importance for color. Normally, this gene ensures strong production of darker pigments, which in turn give the hair a darker tone. This gene plays a key role in the origin of red hair and is mutated in redheads. This gene defect, in turn, means that fewer dark pigments and more light ones are produced.

These pigments are the body-made pigment called melanin. This pigment comes in two different forms. The two variants are pheomelanin and eumelanin. The altered ratio of these two pigments causes people to develop either blonde or red hair. In the origin of red hair, there is considerably more pheomelanin than eumelanin. Blonde people, by contrast, produce both pigments in small amounts.

 

The Origin of Red Hair - Why Red Hair Is Rare

There are various reasons why red hair arises so rarely. The MC1R gene isn't only involved in coloring the hair. A mutation doesn't just pass red hair to its carrier, it also comes with lighter skin. This fact ties into our evolutionary history. Our ancestors from Africa were better able to protect themselves against strong UV radiation with darker skin. When they began migrating out of the warm continent, the amount of sunlight to be endured also dropped, which in turn benefited lighter skin types. These are less protected against UV light, but can produce vitamin D more efficiently with less sunlight.

Another factor affecting the spread of red hair is how red hair is inherited. The gene variants responsible for the origin of red hair are recessive in nature. That means both parents must pass these gene variations on to their children for red hair to be expressed. Other gene variants that promote the production of dark hair are dominant, so they suppress the expression of red hair. Conversely, parents who don't have red hair can have children with red hair if both pass on the respective gene variants for red hair to their children.

 

Why is red hair rare?

  • usually recessive inheritance
  • both parents must pass on the gene
  • "dark hair gene" suppresses expression of red hair