Why does our skin look different in UV portraits? Human hair and skin contains melanin to block cancer-causing ultraviolet light from the sun. The melanin is produced in the deepest of the five layers of the epidermis. Unlike visible light, UV light penetrates the outer layers of our skin and is blocked by the melanin, appearing dark in the portraits. (Sunscreen and UV blocking glasses also appear dark.)
It is often forgotten that the range of light that humans can and can’t see is by no means universal. Many animals—ranging from butterflies to cats to reindeer—see ultraviolet light. As we know, outwardly visible differences of melanin levels have been used by various human societies as a pretext for racial discrimination, subjugation, and enslavement. Viewing each other in UV light is a stark reminder of just how arbitrary and artificial melanin-based social hierarchies are.