Asked by: Antonio Jones, London
Tattoo needles deposit ink beneath the epidermis. This is deep enough that the ink won’t be immediately shed with the skin cells of the upper layers, but macrophage cells from your immune system will gradually absorb the ink and disperse it.
And the UV frequencies in sunlight are energetic enough to break down the ink molecules over time, so tattoos that are always exposed – such as on the fingers or face – fade quicker than those covered by clothing.
Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.