“In 2003, it was predicted that cyanobacteria would be found in extraterrestial environments. The arguments were based on the molecular complexity of cyanobacteria, and the fact that microfossils indistinguishable from modern cyanobacteria had been discovered in cherts 3.5 billion years old. Following W. Schopf, I concluded that there was insufficient time for such organisms to evolve on the early Earth.”