Roughly 4.33 billion years ago, amid a planet still cooling from its own violent birth, Earth quietly crossed a threshold — not into life itself, but into the possibility of it. Researchers have identified this moment as the emergence of an 'RNA world,' the chemical precursor to all living things, arriving before even LUCA, the ancestor common to every organism that has ever existed. It is a date that transforms one of humanity's oldest questions — when did the story of life begin? — from open speculation into something science can now point to, examine, and refine.