As the authors of a recent study published in BMJ attest, society’s red-haired members don’t always get a fair shake. Hoary stereotypes, such as the idea that redheads are also hot heads, are mixed together with actual physiological differences — such as a heightened sensitivity to pain. Now science is getting a better understanding of redheaded physiology than ever before.
In numerical terms, people with red hair are a decided minority. They comprise just 2-6% of the population of the northern hemisphere and 1-2% worldwide. It’s genetics that make them such rare birds.
The carrot-top coloration is caused by a gene on chromosome 16 that affects the melanocortin-1 receptor (MC1R) protein, which often leads to the redheads’ characteristic pale skin and light eyes, as well as a sensitivity to ultraviolet light — which is why they must slather on the sunscreen when they go outside. Because the gene is recessive, both parents must carry it in order for a red-haired child to be born. That’s not difficult — 80% of the global population carries the redheaded gene even most if they do so invisibly.
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