The scientists traced the loss of hair color to the gradual dying off of adult stem cells that form a reservoir that spawns a continuous supply of new pigment-manufacturing cells, called melanocytes, that give hair its youthful hues. Not only do the non-specialized stem cells become depleted, they also progressively make errors, turning into fully committed pigment cells in the wrong place within the hair follicle, where they are useless for coloring hair.

Each hair follicle has a tiny reservoir of adult stem cells that churns out a continuous supply of pigment-making cells. The stem cells naturally start to die off for most people in their 20s.

Knowing what causes graying could lead to drugs to interrupt the process, but Fisher isn't trying to put Grecian Formula out of business. He wants to harness the natural cell death to fight melanoma.

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