“We assumed,” he said, “that when we launched the replicators we were introducing something new to the universe, a wholly new kind of artificial life. That assumption was naive. We—human beings, terrestrial or Martian—weren’t the first sentient species to evolve in our galaxy. Far from it. In fact there’s nothing particularly unusual about us. Virtually everything we’ve done in our brief history has been done before, somewhere, by someone else.”

