Blonde, Brown, Red — How is Human Hair Color Determined?
Hair color is highly variable in Europeans — not so much in the rest of the world. (Why? Our best guess is sexual selection. Some gentlemen really do prefer blondes. The Ice Age seems to have intensified it).
So, what determines the color of our locks? Hair color, needless to say, runs in families.
Eumelanin versus Pheomelanin
All natural hair colors are the result of two pigments. Eumelanin is black. Pheomelanin is red. (Red and yellow dogs and cats are also colored by pheomelanin). The color of your hair comes from the ratio of these two pigments in it. So, black hair is almost all eumelanin and red hair is almost all pheomelanin.
The default human hair color, as it were, is black. If we were talking about animals, we would call this the “wild type.” All but one of the great apes (orang utans) also have black hair. Every other color is a mutation off of this. So, let’s look a bit deeper into hair color genetics.
MC1R
We’re going to start with MC1R. We all have this gene. It makes a protein called the melanocortin 1 receptor. When it…
