Cro-Magnon Virus

The marks the body refuses to wash off are not bruises. They are not scars on the skin. They are written inside you, in the darkest part of every cell, in the language the body uses to run itself — and they were put there by a virus.

Sometime in the deep past — not years ago, not centuries, but millions of years — a virus got into one of your ancestors. Not a cold. Not a fever. This one went further. It threaded itself into the DNA of a single cell, and that cell divided, and divided again, and eventually became a person, who became a line of people, who became you. The virus came with them the whole way. It is still there.

Eight percent of your genome is ancient viral scar tissue. Eight percent. More than the portion that codes for being human. Some of it has been sitting there so long it has gone silent, fossilised into junk. But some of it — and this is the part that takes a moment to land — the body learned to use. Proteins your placenta makes right now, to keep your immune system from attacking a growing child, are built from instructions a virus left behind. The thing that almost killed your ancestor is part of the reason you exist.

Your genome is not a clean blueprint. It is a palimpsest: a document written and overwritten ten thousand times by ten thousand things that were not you, and some of them are still writing.