Humanity is luminous.

Our forebears forfeited the protection of trees and fur. We kept the collarbones of brachiators, but we strode upright across ancient, ever-shifting plains and forests of the African continent. Without fur, our skin, the first line of defence against injury and infection, burned. Precious folic acids destroyed. Immunity compromised. We died of starlight.

But in place of fur, we took up melanocytes. We evolved cellular armours to contend with the radiation of our sun. A writhing celestial plasma-knot that birthed our entire solar system and us with it. Our skin became Kevlar. Interwoven layers of eumelanin and phaeomelanin deflects slashes of ultra-violet light and free radicals. Protects the helical delicacy of our DNA.

And like that sun, like the planet we walk on and the planets around us, and the bands of left-over creation at the edge of our solar system, we wander. The bulwark of our bodies changes with latitude and altitude. Some of us lighten. Our eyes mutate. We grow stouter, paler, and starve for starlight. Frostbite finds our melanocytes and spears them with ice fractals. The sun sinks for months at a time. But it rises again, a little larger, a little redder, a little hotter. Our skin acts as a living scroll. Imprinted by the life of something cosmic.

Because we walk in the light and the light walks with us.

(Image credit: NASA/SDO)