Because of a genetic mutation in the chromosomes that make up pair 16 in redheads. This mutation alters the production of two pigments – pheomelanin, which is reddish or yellowish in color, and eumelanin, which is brownish or black in color – responsible for coloring hair and fur, making them red or reddish.
A “side effect” of this mutation is the appearance of freckles, which are nothing more than spots caused by increased concentration of melanin in certain parts of the body. But even those who don’t carry this genetic heritage can have freckles. In this case, the spots are a skin response to the sun’s aggression – it pigments itself to block the penetration of the sun’s rays.
The biochemistry of red hair, an anomaly known as rutilism, was only unveiled at the end of the last century. Some researchers believe that the first redheads appeared on Earth about 50,000 years ago in Africa.
Estimates of the number of redheads in the world’s population are not very precise, but it is believed that people with red hair are 1 to 4% of the total (from 60 million to 240 million people). And it is in Great Britain that they are concentrated: in Scotland, one in ten people is a redhead.
Red hair, by the way, is not exclusive to the human species. Goats, squirrels and orangutans can also have red fur.
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