The shared ancestor of every living organism on the planet lived at least 3.9 billion years ago – adding weight to theories that life started 100 million years earlier than we thought, at a time when the Earth was still being pummelled by meteorites .

That’s according to a study that has combined genetic and fossil evidence to build a timeline of crucial shifts in the early evolution of life. The study also sheds new light on the birth of complex cells, which today make up all …