‘Chameleon’ tattoos change color, may help diagnose illness

When a pair of tourists hiking the Alps stumbled across the frozen remains of the mummy Ötzi in 1991 they also, unknowingly, discovered the oldest known examples of tattoos in history. The 5,300-year-old body, more famously known as the Iceman, has 61 tattoos arranged in patterns of straight lines scratched across his skin.