There's a pigment called eumelanin that is higher in people with darker hair. Another pigment, pheomelanin, is lower in dark hair.
I guess the pigments in your hair can change, like the dark or light pigments that determine the tone of your hair.
I have brown hair. It is very common in human beings. In fact, it's second only to black hair in how common it is. That's what I said, haha. I wish I had red hair. I think it looks really cool. That's nice. Once again, brown hair is the second-most common color. I think red hair is mostly present in northern climates. It is pretty rare where I live. Oh, that's interesting. As for brown hair, it can vary from light to almost black in shade. Mine is on the lighter side. The sun makes it look almost blonde at times. Oh, yeah? So, yeah, brown hair has many shades, from light to almost black. Yeah, that's so true it should be said twice. What makes hair the color it is, anyway?
It is characterized by higher levels of the dark pigment eumelanin and lower levels of the pale pigment pheomelanin.