Written in Permanent Ink

In 1974, Swedish biochemist Tomas Lindahl made an unsettling discovery: human DNA is chemically unstable. Every cell in your body experiences tens of thousands of damage events every single day — from sunlight, oxidation, even the simple act of breathing. Left unchecked, this accumulation would make human life impossible within days. But Lindahl didn't stop there. He found something equally astonishing: our cells contain an elaborate, tireless repair system.…