Why Does Hair Grow Gray When People are Old?
Some of the cells of the hair contain a pigment (coloring mattef). As human bodies grow old, most of them lose the power to make new pigment, so that the hairs are colorless, or white. Some people lose the power to make the pigment when they are still quite young others do not grow gray until they have reached a very advanced age. General health and good care of the hair may aid in keeping the color. However, loss of hair pigment runs in families, and many physicians believe that it is a hereditary trait. The condition of the nervous system has an effect upon the hair. Persons under a serious nervous strain have been known to grow gray quickly. We hear stories of people who turned white in a single night, because of shock, or fright or fear. Probably these stories are exaggerations; yet it is true that men and women under stress have become whitehaired in a few months. Scientists have studied for years, trying to find out what happens in the body that stops production of the color cell
