Why Can’t Humans Have Naturally Blue Hair?
Human hair cannot be naturally blue because its colour comes from only two pigments: eumelanin, which gives dark shades, and pheomelanin, which gives golden and reddish ones. Every natural hair colour is a mix of the two, and neither can produce blue, green or purple.
What decides the colour of your hair?
Two natural pigments. Eumelanin is responsible for dark shades, from chestnut brown to jet black: the more eumelanin you have, the darker your hair. Pheomelanin is responsible for golden or reddish hues.
Key facts
- Hair colour is determined by two pigments: eumelanin and pheomelanin.
- More eumelanin means darker hair.
Why do we have only these two pigments?
The answer is likely evolution. For millions of years, our ancestors needed to blend in with their surroundings to avoid predators and to hunt.
Where can I read the full story?
This is a short version of “Why Don’t Humans Naturally Have Blue or Red Hair?” from OYLA 12+, Vol. 8, Issue 8. The same issue tells the story of Louis-Nicolas Vauquelin, the chemist who first studied what hair is made of.
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