What if, she mused to Y, what if there are people there, people more or less like us biologically? Like what if primate evolution is always something that comes of small arboreal mammals?
That seems, well, improbable, he answered. That three billion years of natural selection would unfold the same way.
Ok, she changed course, forget about primates. What if the dominant species arose from a very different biological order? Like an aquatic species with advanced intelligence? Primates aren’t the only path to that.
Let me try a different way of explaining, she said.