“The earliest evidence we have of tattoos, not surprisingly, is cosmetic,” says Lars Krutak. Tattooed on the upper lip of a 7,000-year-old mummy from the Chinchorro culture of northern Chile and southern Peru is a thin pencil mustache. “But, the second oldest we have is medicinal,” he adds.

http://www.smithsonianmag.com/science-nature/can-tattoos-be-medicinal-156450609/?no-ist