Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness

by Peter Godfrey-Smith

Cephalopods are an island of mental complexity in the sea of invertebrate animals. Because our most recent common ancestor was so simple and lies so far back, cephalopods are an independent experiment in the evolution of large brains and complex behavior. If we can make contact with cephalopods as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over. This is probably the closest we will come to meeting an intelligent alien.

The octopus is not Ishmael from Moby-Dick, who escaped alone to tell the tale, but a distant relative who came down another line, and who has, consequently, a different tale to tell.

Once the same chemicals are being sensed and produced, there is the possibility of coordination between cells. We have reached the birth of social behavior.

This is because they hunt at night, when moonlight would normally cast their body’s shadow down to predators below. Their internal lights cancel the shadow.

The chemistry of life is an aquatic chemistry. We can get by on land only by carrying a huge amount of salt water around with us.

chemicals that are made because they’ll be perceived and responded to by others—brings us to the threshold of signaling and communication.

Sensing and signaling between organisms gives rise to sensing and signaling within an organism.

Rather, animals arose from a cell whose daughters did not separate properly during cell division.

A sponge? It seems that one could hardly pick a more implausible ancestor:

animals most distantly related to us; instead, this title may belong to the comb jellies.

mass of such cells concentrated together, sparking in a chemo-electrical storm of repurposed signaling, become a brain.

According to the first view, the original and fundamental function of the nervous system is to link perception with action