Most people think grey hair is just aging, but your biology sends the signal long before the color changes. Researchers have already mapped out the internal pathways that switch pigment on or Stress sensing in the human greying hair follicle: Ataxia Telangiectasia Mutated (ATM) depletion in hair bulb melanocytes in canities prone scalp Scientific Reports Hair Aging and Oxidative Stress Your Best Hair at Any Age Arey Natural products and their derivatives as candidate treatments for hair greying: from drug discovery to molecular mechanisms Chinese Medicine Springer Nature Link