Between one and two billion years ago,
a remarkable episode occurred in the history of life.
Until then, the only living things on Earth were bacteria.
But the events of that distant time gave birth to the complex cell
and, from that starting point, to all plants, fungi, and animals.
We now know that the complex cell formed through the merging of symbiotic bacteria.
But why should it have happened then,
and why was it never repeated?
Through vivid accounts of beautiful single-celled forms,
symbiosis in coral reefs today, and fossils from two billion years ago,
Martin Brasier, well known for his work on early life,
gathers clues about the conditions that enabled this unique turning point for life on Earth.