The history of life
The same milestones, cut differently: only those the corpus files under life or evolution. Thirty-seven of them, from the last common ancestor of everything alive to the genome we now edit. What this page shows is not a lineage — no tree here, and no descent. It shows when each thing was invented, and how long the gaps between the inventions are: two billion years between the first cell and the first nucleus, half a billion between the first animals and the first flower. The gaps are the point, and only a timeline shows them.
37 milestones out of 200, in 10 chapters
Hadean4.54 Ga → 4.03 Ga
Five hundred million years without a single rock left to show for them. The eon takes its name from the underworld, and it is the only division of Earth's history defined by the absence of what should record it.
- The Ancestor of Everything Alive~4.2 billion years ago (estimates 4.3 to 3.5 Ga)
- Where Life May Have Started~4.2 billion years ago (setting debated)
Eoarchean4.03 Ga → 3.6 Ga
The dawn era, and the first four hundred million years for which any rock survives at all. What it holds is thin, contested, and among the most important evidence there is.
See it on the timelinePaleoarchean3.6 Ga → 3.2 Ga
Four hundred million years in which life stops being a contested trace and becomes a structure you can walk up to and touch.
See it on the timelineMesoarchean3.2 Ga → 2.8 Ga
Somewhere in this era the crust may start behaving as it does today, one plate sliding beneath another and driving the machinery that builds continents.
See it on the timelinePaleoproterozoic2.5 Ga → 1.6 Ga
Nine hundred million years, and the most violent change the planet has undergone: the air fills with oxygen, and almost everything alive is poisoned by it.
- The Great Oxidation Event~2.4 billion years ago
- The Cell That Swallowed a Bacterium~1.9 billion years ago (order of events debated)
- The First Complex Cells~2.0–1.8 billion years ago
- A Lost World, Read in Its Molecules~1.64 billion to 800 million years ago
Mesoproterozoic1.6 Ga → 1 Ga
Six hundred million years in which, as far as anyone can tell, remarkably little happens. They sit at the heart of what the literature calls the boring billion, and the nickname is a confession.
- The Ceiling That Held for a Billion Years~1.6 to 0.8 billion years ago
- The Origin of Sex~1.2 billion years ago
Neoproterozoic1 Ga → 539 Ma
Four hundred and sixty million years in which ice reaches the tropics more than once, a supercontinent breaks apart, and the first animals appear.
- The First Animals~800 million years ago (claims 890 to 635 Ma)
- Large Life, Soft and Unarmed~575 to 539 million years ago
Paleozoic539 Ma → 252 Ma
Two hundred and eighty-seven million years, from the first shelled animals to the worst extinction in the record. Life leaves the water in this era and never fully returns.
- The Cambrian Explosion~540–518 million years ago
- The First Backbones~518 million years ago
- The Window on Soft Bodies~518 to 500 million years ago
- The First Eyes~515 million years ago
- Plants Colonise the Land~470 million years ago
- The First Mass Extinction~445 million years ago
- Vertebrates Walk onto Land~390 million years ago
- The Invention of the Seed~372 million years ago
- The Line That Leads to Us~315 to 300 million years ago
- The Great Dying~252 million years ago
Mesozoic252 Ma → 66 Ma
A hundred and eighty-six million years between two catastrophes: the only era on the chart that both begins and ends with a mass extinction.
- Warm Blood~233 million years ago
- Dinosaurs Start Small~233–230 million years ago
- The First Mammals~220–205 million years ago
- The Largest Animals That Ever Walked~190 to 145 million years ago
- The First Flowers~140 million years ago (origin debated)
- Bees and Flowers~123 to 100 million years ago
Cenozoic66 Ma → 2026
The last sixty-six million years, in which mammals inherit a world emptied by an asteroid, grasslands spread, ice returns, and one primate lineage ends up drawing timelines.
- The Asteroid That Ended the Dinosaurs66.0 million years ago
- The Mammals Fill the Gap~66 to 56 million years ago
- First Primates~55 million years ago
- The First Departure~2.1 to 1.8 million years ago
- Descent with Modification1859 CE
- The Rules of Inheritance1866 CE
- Reading Time in Proteins1962 to 1965 CE
- A Third Branch of Life1977 CE