If the level of interest the public has in their gray hair could only be transferred to an interest in practical work to repair aging, how much better off we'd be. Here is more research into the biological causes of loss of hair pigmentation with aging: "Wnt signaling, already known to control many biological processes, between hair follicles and melanocyte stem cells can dictate hair pigmentation. ... We have known for decades that hair follicle stem cells and pigment-producing melanocycte cells collaborate to produce colored hair, but the underlying reasons were unknown. We discovered Wnt signaling is essential for coordinated actions of these two stem cell lineages and critical for hair pigmentation. ... The study suggests the manipulation of Wnt signaling may be a novel strategy for targeting pigmentation such as graying hair. The research study also illustrates a model for tissue regeneration. ... Using genetic mouse models, researchers were able to examine how Wnt signaling pathways enabled both hair follicle stem cells and melanocyte stem cells to work together to generate hair growth and produce hair color. Research also showed the depletion (or inhibition or abnormal) Wnt signaling in hair follicle stem cells not only inhibits hair re-growth but also prevents melanocytes stem cell activation required for producing hair color. The lack of Wnt activation in melanocyte stem cells leads to depigmented or gray hair."

Link: http://www.sciencedaily.com/releases/2011/06/110614115046.htm