Octopus intelligence

Just how smart is an octopus?

The cleft in the tree of life that separated the lineages that led to vertebrates and invertebrates happened 600 million years ago. One path, as Godfrey-Smith explains, led to progressively more complex intelligences, in the form of fish, reptiles, birds and mammals. The other path, while producing sophisticated means of sensing and surviving in a dangerous world, eschewed mental complexity. The cephalopods represent an island of intelligence in this invertebrate sea. They represent a separate experiment in the evolution of the mind.

Godfrey-Smith is not a scientist but a philosopher. This is, he says, a philosophy book as well as a scientific one. The question with which he wrestles is that of consciousness: “Does it feel like something to be one of the large-brained cephalopods, or are they just biochemical machines for which all is dark inside?”