Within only seven hundred million years of Earth's formation, while traces of the Late Heavy Bombardment were still fading in the newly cooled oceans, simple cellular life had emerged. Graphite enrichments and putative microfossils in the Isua greenstones of Greenland and the Pilbara craton of Western Australia are debated as the earliest direct evidence.

These first organisms were prokaryotes: single-celled, lacking nuclei or internal organelles. They drew energy from chemosynthesis or simple phototropic reactions. Easy as the story is to summarise, the transition from abiotic chemistry to the first replicator remains one of biology's deepest open questions — researchers continue to probe clay mineral surfaces, hydrothermal vents, and the RNA world hypothesis as plausible paths.

What matters is this: every known living thing — bacteria, archaea, fungi, plants, animals, humans — belongs to an unbroken chain of copying that reaches back to these early cells. We all share the same molecular grammar.