Here's Why Tattoos Last Forever Despite Our Dying Skin Cells

The history of tattoos is long and rich with the earliest evidence of tattooed humans dating back to 4th millennium BC. Archeologists have uncovered tools, ancient art, and mummified skin that prove the practice has been alive and well for centuries.

The permanence of tattoos on skin, however, is something that's bothered scientists for quite some time. It is common knowledge that our skin cells constantly regenerate – so does tattoo ink last for years and years without fading out completely? A new fascinating research from France is bound to give us the answer.

(Photo: Taylor Harding via Unsplash)

Up until now, it was known why our skin cells soak up the pigment in the first place – it's all thanks to the immune cells called macrophages that target and soak up the ink as they would a basic infection. However, what happens when old cells, including macrophages, die off and are replaced with new ones?

According to a group of scientists from Aix Marseille Université, the dead cells release the tattoo ink into neighboring cells, thus creating a continuous cycle and allowing your tattoo to stay intact for decades to come. Leader of the research group, Sandrine Henri, explained:

"We think that, when tattoo pigment–laden macrophages die during the course of adult life, neighboring macrophages recapture the released pigments and insure in a dynamic manner the stable appearance and long-term persistence of tattoos."

The experiment that has lead to this discovery involved tattooing the tails of mice. After the macrophages in their skin soaked up the pigment, the scientists killed of those cells only to find the tattoo didn't change. In another try, the team transferred a piece of tattooed skin from one mouse to another, and found that after six weeks, the new mouse's cells had absorbed the pigment as well.

If you think 'well, who cares' wait until you or someone you care about gets a horrendous tattoo on their neck and wants to remove it. Apparently, this new finding is super helpful in understanding how to better remove unwanted tattoos. According to the researchers:

"Tattoo removal can be likely improved by combining laser surgery with the transient ablation of the macrophages present in the tattoo area.

As a result, the fragmented pigment particles generated using laser pulses will not be immediately recaptured, a condition increasing the probability of having them drained away via the lymphatic vessels."

Hooray science!

"Because tattoo pigment can be recaptured by new macrophages, a tattoo appears the same before (left) and after (right) dermal macrophages are killed." (Photo: Journal of Experimental Medicine)