Why Does Hair Turn Gray When People Are Old?
Different hair colors, from blond to black, are determined by the melanin, or coloring matter, in your hair cells. This melanin is added to the new hair cells as they form in the hair roots. Less and less melanin is deposited in newly forming hair as a person grows older.
Without this coloring matter, the hair becomes gray and then white. Some people have gray hair when they are still quite young, and some people keep their hair color even when they are old.
How early we get gray hair is determined by our genes. This means that most of us will start having gray hairs around the same age that our parents or grandparents first did.
Gray hair is more noticeable in people with darker hair because it stands out, but people with naturally lighter hair are just as likely to go gray.
From the time a person notices a few gray hairs, it may take more than 10 years for all of that person’s hair to turn gray. Many animals, including cats and dogs, also grow gray as they get older.