The Great Dying


Permian extinction
252 million years ago

Just as the reptiles were flourishing, life on Earth faced perhaps its greatest challenge. The Permian extinction was the worst mass extinction in the planet’s history, obliterating up to 96% of marine species and similar numbers of land animals. We don’t know for sure what caused it, but massive volcanic eruptions – creating what is now the Siberian Traps – may have been to blame. In the aftermath, the first dinosaurs evolved.

See other: History of Life

On Body and Brain


Batiatus: A good body with a dull brain is as cheap as life itself.

– Lewis. E. (Producer), Kubric. S. (Director). (1960). Spartacus [Motion Picture]. United States: Universal Studios

On a Life in Fear


“A life lived in fear is a life half-lived.”

– Spanish proverb

On Fear and Understanding


“Nothing in life is to be feared. It is only to be understood.”

– Marie Curie

Snowball Earth


A frozen world
850-635 million years ago

Earth froze over again, twice, in the space of 200 million years. The ice may well have stretched all the way from the poles to the equator. This second Snowball period may have triggered the evolution of the first complex animals. The first complex organisms, weird tube- and frond-shaped things called the Ediacarans, appeared soon after.

See other: History of Life

Multicellular Life


Big organisms
1 billion years ago?

For the first time, life was not just made up of single cells. Now cells were teaming up to form larger organisms with things like mouths, limbs and sense organs. It’s hard to say when this happened: there are fossils of large organisms dating back 2.1 billion years, but these may simply have been colonies of bacteria. Different groups of organisms probably evolved multicellularity independently, with plants managing it before animals.

See other: History of Life

Endosymbiosis


Complex cells
2-1 billion years ago

The first organisms were simple cells like modern bacteria, but some of them became much more internally complex. These ‘eukaryotes’ developed lots of specialised equipment within their cells. They also had a new source of energy: sausage-shaped objects called mitochondria that were once free-living bacteria, but which were absorbed in a process called endosymbiosis. Every animal and plant you have ever seen is a eukaryote.

See other: History of Life