Overview
“I’m gonna wash that gray right outta my hair.” Years ago, the marketing wizards at Clairol switched the lyrics to a song from the musical “South Pacific” to encourage women to cover up gray hair with their product. It’s a decision many people–men and women–grapple with, especially as they get older and grayer. The bigger question is why it happens in the first place.
Structure of Hair
Hair is mostly made up of keratin, a protein. The chemistry department at the University of South Carolina says each hair springs up from a follicle in the skin that houses the root bulb. According to USC, the bulb’s basic components are keratin, the pigment melanin and tiny amounts of metals. The Library of Congress describes melanin as being made up of melanocytes, cells that are specialized for the purpose of injecting pigment into the keratin that makes up the bulk of the hair.
Hair Color
Melanin starts forming in the body before birth, according to the Library of Congress. There are two kinds: eumelanin, which is dark, and phaeomelanin, which is light. The ratio and blend of these two types determines hair color. In an article in Scientific American, Coco Ballantyne says, “Hair that has lost most of its melanin is gray; hair that has lost all of this pigment is white.”
Theories
The Library of Congress cites Dr. Desmond Tobin, a biology professor in England, who has some ideas as to why hair turns gray as people age. He says the hair follicle is programmed with a sort of clock that eventually slows down or completely stops the activity of the melanocytes, so they no longer inject the keratin with pigment. He also theorizes that each hair follicle has a set amount of pigment it can provide, and we eventually run out as we age. Our genetics determine how young, or how old, we are when this happens, as well as whether it happens all at once or over a long period.
Other Considerations
Other factors that the Library of Congress notes can affect the cessation of melanocyte activity include personal ones–such as genetic defects and hormones–and environmental ones, such as climate, pollutants, toxins and exposure to chemicals. For the latter category, the longer you’re alive, the more exposure you have to these elements.
The Stress Myth
Coco Ballantyne explored the notion of stress causing gray hair. Some say that Marie Antoinette’s hair went completely white from stress on the eve of her execution by guillotine. Closer to home, parents often cite children’s misbehavior as the reason for their gray hair. Though scientists haven’t yet found a direct link between stress and gray hair, it’s a possibility. Stress hormones can lead to the production of free radicals. Free radicals destroy cells–and this could include melanocytes. Tyler Cymet, the head of family medicine at Sinai Hospital in Baltimore, told Ballantyne that basically, you’re genetically inclined to go gray at a certain point, but stress levels can swing that set point five to 10 years in either direction.
