The first signs of life on Earth date back 4 billion years, but for most of Earth’s history the most complex organisms were bacteria. 

Really complex life, composed of ‘eukaryotic’ cells that are strikingly different to bacteria, emerged just once, around 1.5 billion years ago. This peculiar trajectory is not explained by genes alone, but might be shaped by the strange mechanism through which cells generate their energy, by electrical force-fields on their membranes. Keeping this electrical force alive over billions of years could explain many longstanding puzzles in biology, such as the evolution of two sexes.