French researchers say they have found the answer, and it's a little bit surprising. They found that immune system cells called macrophages eat the ink, and then pass it to their replacements when they die. So the tattoo ink doesn't stain skin cells, as many people had believed.

Possessed of ancient roots, tattoos have in recent years gone from being taboo to part of the social fabric. The next step? Their acceptance as art works that can even outlive their owners, writes Thomas Hobbs.

Mainstream Acceptance: Tattoos have become increasingly accepted and normalized in many parts of the world. They are no longer solely associated with fringe groups or rebellion but are embraced by people from diverse backgrounds, professions, and walks of life.