Humans have been tattooing themselves for thousands of years. In fact, Europe’s oldest natural mummy, Ötzi, which is approximately 5,200 years old, has tattoos. How tattoos work is that a needle punctures the skin and ink is injected into the second layer, called the dermis. Usually, if something is in the dermis, white blood cells clear it from the body, but pigment particles are too big for white blood cells to consume, meaning the ink just stays in place. Over the past several decades…
