Origin Story: A Big History of Everything

by David Christian

We get the first good evidence for large numbers of multicellular organisms early in the Ediacaran period, which lasted from around 635 million years ago to around 540 million years ago. For the first time, we see the three familiar groups of large organisms: plants, which depend on photosynthesis so they can usually sit still and suck up sunlight; fungi, which scavenge decomposing organic material; and animals, which have to be alert and mobile because they survive by hunting down and eating other organisms. With the emergence of huge numbers of organisms that got their energy by consuming other organisms, the biosphere became more complex, more diverse, and more hierarchical as energy from sunlight was passed through different trophic levels, from plants to animals and fungi.