Gray hair is usually seen as a sign of aging — but science suggests it may also reflect a powerful protective response inside the body. As hair turns gray, it signals that pigment-producing cells (melanocytes) have slowed down or stopped due to cellular stress. Interestingly, this same stress response is linked to mechanisms that prevent damaged cells from turning cancerous. When cells experience DNA damage or oxidative stress, the body can activate protective pathways that halt cell division or