Mind Evolved Twice

Mind evolved twice. This is not a metaphor but an empirical claim about the history of life on Earth. The common ancestor of vertebrates and cephalopods was a small, flat creature with little in the way of a nervous system, living something like six hundred million years ago. Everything we recognize as mental—sensation, attention, learning, problem-solving, and perhaps subjective experience—came later, independently, on two entirely separate evolutionary roads. The vertebrate brain and the cephalopod nervous system are convergent solutions to the problem of living in a complex, variable world. When Peter Godfrey-Smith argues that looking into the eye of an octopus is the closest a human being can come to meeting an intelligent alien, he is making this empirical point: the octopus arrived at intelligence by different means, through different architecture, from a different starting point. It is genuinely other. And the fact that mind has