What comes to mind when you think of gray hair? Wisdom? The inexorable march of time? The beauty of the old? A pesky problem that must be dyed into submission?

Though you might associate graying with the death of your lovely tresses, gray hair is actually associated with rapid hair growth. Gray or white hair is generally longer and thicker than black hair: Just think about that one long white eyebrow hair of yours that sticks out annoyingly past all the others and keeps growing back, hydra-like, when you pluck it out. Yes, gray hair also grows faster and for a longer time than black hair.

A study of scalp and eyebrow hair revealed that the genes responsible for producing two of the main structural proteins in hair are twice as active in white hair as in black hair. The researchers, who published their findings in the British Journal of Dermatology, also looked at substances called growth factors that control how and where hair grows over time. They discovered that one of the substances that boosts hair growth is more active in white hairs than in black. On the other hand, another substance that slows hair growth is more active in black hair.

But how does hair growth translate to loss of hair color? Hair, like skin, gets its color from a compound called melanin. There are special cells that produce melanin. During hair growth, chemicals are produced that can kill or prematurely age those color-giving cells. One such chemical is hydrogen peroxide, which is well-known as a bleaching agent. In the end, though death of certain kinds of cells contributes to grayness, you can also blame the gray on too much growth.

What to do? Well, if you ever get tired of coloring and plucking your gray hair, take your cue from silver foxes like George Clooney, Anderson Cooper and Jamie Lee Curtis and embrace the gray.