The chemical/genetic makeup of red hair....

Among the various artistic and scientific endeavours I undertake during class is a near constant examination of the hairs that fall out of my beard onto my paper (for some reason that sounds gross). Anyway, I have red hair, but one thing I don’t understand is that the hairs themselves aren’t actually entirely red. They start out white (I’m talking about the follicles, not the little ball sometimes on the end) at the base, then they get clearer, then get darker and darker towards the end.

This, I presume, explains why whenever I cut my hair (I cut it short) my hair is lighter, more like a strawberry blond.

Why is this? Why is my hair not one uniform color? Does the color change as the cells in each follicle die or whatever the cells do after they grow out? Are all people’s hair like this (my girlfriend has jet black hair, but she won’t let me pull one out…obviously not as devoted to science as I am)?

Just curious…