melanin. It is one of the oldest molecules in biology and is found throughout the living world. It doesn’t just color skin. It gives birds the color of their feathers, fish the texture and luminescence of their scales, squid the purply blackness of their ink. It is even involved in making fruits go brown. In us, it also colors our hair. Its production slows dramatically as we age, which is why older people’s hair tends to turn gray.
