When a certain gene called Bcl2 isn't working right in mice, the stem cells that give rise to hair color die off when hair follicles go dormant, but the actual color-making cells are fine—this leads...

In mice, when a specific gene called Bcl2 isn't working, the stem cells that make pigment die off when the hair cycle pauses, but the mature pigment cells stay alive — showing that stem cells really rely on this gene to survive.

As we get older, the cells that give hair its color start to die off because of stress and lower levels of a protective protein, which is why hair turns gray and doesn’t grow back 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.

When mice experience sudden stress, it causes the cells that give hair its color to panic and leave their home in the hair follicle, burning out too soon and making the fur turn gray forever.

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.