In mice with a broken Dguok gene, their hair turns gray because the stem cells that give color to hair disappear early, even before the color actually fades.

Going gray might happen because the stem cells that keep your hair colored stop working properly as you age, according to studies in people and specially tagged mice.

As we age, the stem cells that give color to our hair can start acting up — they might turn into pigment cells too soon or in the wrong place, which could be why our hair turns gray.

Going gray might happen because the stem cells that give rise to hair color cells get damaged over time, not because the color-making cells themselves stop working. Keeping these stem cells healthy could be key to keeping your hair colored as you age.

When a certain gene is turned off in pigment cells in mice, their fur starts turning gray around 4 months old, and by 8 months, most of their hair has lost color — but normal mice don’t go gray, so this gene might help keep hair colored.

As we get older, the stem cells that keep our hair colored might stop working properly because of problems in their internal repair system, and once they're gone, our hair turns gray for good.