Field guide
Long before you, there was life.
17 short entries on the bodies, worlds and crises behind Before Us, oldest first. Each keeps evidence apart from reconstruction, and links to its sources. Free, always.
About 4.2 billion years ago
LUCA, the last universal common ancestor
Every living thing shares one distant ancestor. It was not the first life, just the last one we all have in common.
Background
Perhaps a billion years ago
Between the Grains
A single cell with a nucleus, hunting and hiding in the film of water between grains of sand. By then, life was already ancient.
In the gameBetween the single cell and the first animals
Becoming a body
A body is not just a bigger cell. Somewhere on our line, cells began to stay together and coordinate.
Turning points
About 555 million years ago
The Garden of Ediacara
A tiny soft body with a front and a back, creeping over a sea floor carpeted in microbes.
In the game
About 518 million years ago
Backbone
A little fish with eyes and the beginnings of a backbone, in a sea suddenly full of hunters.
In the gameAbout 444 million years ago
The end-Ordovician extinction
Ice spread, seas cooled and shallow waters drained. One of the largest extinctions in the history of animal life struck the oceans.
Extinctions
About 375 million years ago
The Water’s Edge
A lobe-finned fish with lungs and a neck, leaning on its fins in shallow water at the edge of the first forests.
In the gameAbout 374 and 359 million years ago
The Late Devonian crises
Not one disaster but two, separated by about fifteen million years. The second reshaped the history of animals with backbones.
ExtinctionsAround 355 million years ago, perhaps earlier
Life away from water
Amniotes, the group that includes reptiles, birds and mammals, could live and breed away from water. Their origin may be much older than once thought.
Turning pointsAbout 252 million years ago
The end-Permian extinction
Earth’s most severe extinction. Volcanic heat released vast amounts of greenhouse gas, and the aftermath lasted a very long time.
ExtinctionsAbout 201 million years ago
The end-Triassic extinction
A warming world, and landscapes that burned. Dinosaurs came through this crisis; they did not end here.
Extinctions
About 67 million years ago
Beneath Giants
A small warm-blooded mother foraging by night beneath the feet of dinosaurs, with a litter to feed.
In the gameAbout 66 million years ago
The end-Cretaceous extinction
An asteroid struck what is now Mexico. Dust darkened the sky, and the world that followed was cold, dim and hungry.
ExtinctionsWithin a few hundred thousand years after the impact
The first primates
Soon after the asteroid, small tree-living primate relatives spread through recovering forests.
Turning points
About 10 million years ago
The Canopy
A young ape crossing the treetops with its family: grasp, sway and keep each other safe.
In the gameAbout 3.6 million years ago
Walking upright
Footprints pressed into volcanic ash in Tanzania show a human-like stride, long before our own genus appeared.
Turning pointsAbout 100,000 years ago
The Ember
People of our own species, carrying a living ember through a storm along a southern African coast.
In the game