Any attempt to explain a singular event will always have the appearance of a fluke about it. How can we prove it one way or another? There might not be much to go on in the event itself, but there may be clues concealed in the aftermath, a smoking gun that gives some indication of what happened. Once they cast off their bacterial shackles, the eukaryotes became enormously complex and diverse in their morphology. Yet they did not accrue this complexity in an obviously predictable way: they came up with
