Your skin cells are constantly regenerating, so how is it that a tattoo can last for decades? Fascinating new research from France sheds new light on how this works: Your skin cells soak up the pigment, then release it when they die for other cells to pick up. This cycle continues ad infinitum—the circle of tattooed life. In the research, published this week in the Journal of Experimental Medicine, scientists tattooed the tails of mice.