Peter Godfrey-Smith - Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness

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For all those who work to protect the oceans

The demand for continuity has, over large tracts of science, proved itself to possess true prophetic power. We ought therefore ourselves sincerely to try every possible mode of conceiving the dawn of consciousness so that it may not appear equivalent to the irruption into the universe of a new nature, non-existent until then.

William James, The Principles of Psychology , 1890

The drama of creation, according to the Hawaiian account, is divided into a series of stages At first the lowly zoophytes and corals come into being, and these are followed by worms and shellfish, each type being declared to conquer and destroy its predecessor, a struggle for existence in which the strongest survive. Parallel with this evolution of animal forms, plant life begins on land and in the seaat first with the algae, followed by seaweeds and rushes. As type follows type, the accumulating slime of their decay raises the land above the waters, in which, as spectator of all, swims the octopus, the lone survivor from an earlier world.

Roland Dixon, Oceanic Mythology , 1916

On a spring morning in 2009, Matthew Lawrence dropped the anchor of his small boat at a random spot in the middle of a blue ocean bay on the east coast of Australia, and jumped over the side. He swam down on scuba to where the anchor lay, picked it up, and waited. The breeze on the surface nudged the boat, which started to drift, and Matt, holding the anchor, followed.

This bay is well-known for diving, but divers usually visit only a couple of spectacular locations. As the bay is large and typically pretty calm, Matt, a scuba enthusiast who lives nearby, had begun a program of underwater exploration, letting the breeze carry the empty boat around above him until his air ran out and he swam back up the anchor line. On one of these dives, roaming over a flat sandy area scattered with scallops, he came across something unusual. A pile of empty scallop shellsthousands of themwas roughly centered around what looked like a single rock. On the shell bed were about a dozen octopuses, each in a shallow, excavated den. Matt came down and hovered beside them. The octopuses each had a body about the size of a football, or smaller. They sat with their arms tucked away. They were mostly brown-gray, but their colors changed moment by moment. Their eyes were large, and not too dissimilar to human eyes, except for the dark horizontal pupilslike cats eyes turned on their side.

The octopuses watched Matt, and also watched one another. Some started roaming around. Theyd haul themselves out of their dens and move over the shell bed in an ambling shuffle. Sometimes this elicited no response from others, but occasionally a pair would dissolve into a multi-armed wrestle. The octopuses seemed to be neither friends nor enemies, but in a state of complicated coexistence. As if the scene were not sufficiently strange, many baby sharks, each just six inches or so long, lay quietly on the shells as the octopuses roamed around them.

A couple of years before this I was snorkeling in another bay, in Sydney. This site is full of boulders and reefs. I saw something moving under a ledgesomething surprisingly largeand went down to look at it. What I found looked like an octopus attached to a turtle. It had a flat body, a prominent head, and eight arms coming straight from the head. The arms were flexible, with suckersroughly like octopus arms. Its back was fringed with something that looked like a skirt, a few inches wide and moving gently. The animal seemed to be every color at oncered, gray, blue-green. Patterns came and went in a fraction of a second. Amid the patches of color were veins of silver like glowing power lines. The animal hovered a few inches above the sea floor, and then came forward to look at me. As I had suspected from the surface, this creature was big about three feet long. The arms roved and wandered, the colors came and went, and the animal moved forward and back.

This animal was a giant cuttlefish. Cuttlefish are relatives of octopuses, but more closely related to squid. Those threeoctopuses, cuttlefish, squidare all members of a group called the cephalopods . The other well-known cephalopods are nautiluses, deep-sea Pacific shellfish which live quite differently from octopuses and their cousins. Octopuses, cuttlefish, and squid have something else in common: their large and complex nervous systems.

I swam down repeatedly, holding my breath, to watch this animal. Soon I was exhausted, but I was also reluctant to stop, as the creature seemed as interested in me as I was in it (in him? in her?). This was my first experience with an aspect of these animals that has never stopped intriguing me: the sense of mutual engagement that one can have with them. They watch you closely, usually maintaining some distance, but often not very much. Occasionally, when Ive been very close, a giant cuttlefish has reached an arm out, just a few inches, so it touches mine. Its usually one touch, then no more. Octopuses show a stronger tactile interest. If you sit in front of their den and reach out a hand, theyll often send out an arm or two, first to explore you, and thenabsurdlyto try to haul you into their lair. Often, no doubt, this is an overambitious attempt to turn you into lunch. But its been shown that octopuses are also interested in objects that they pretty clearly know they cant eat.

To understand these meetings between people and cephalopods, we have to go back to an event of the opposite kind: a departure, a moving apart. The departure happened quite some time before the meetingsabout 600 million years before. Like the meetings, it involved animals in the ocean. No one knows what the animals in question looked like in any detail, but they perhaps had the form of small, flattened worms. They may have been just millimeters long, perhaps a little larger. They might have swum, might have crawled on the sea floor, or both. They might have had simple eyes, or at least light-sensitive patches, on each side. If so, little else may have defined head and tail. They did have nervous systems. These might have comprised nets of nerves spread throughout the body, or they might have included some clustering into a tiny brain. What these animals ate, how they lived and reproducedall are unknown. But they had one feature of great interest from an evolutionary point of view, a feature visible only in retrospect. These creatures were the last common ancestors of yourself and an octopus, of mammals and cephalopods. Theyre the last common ancestors in the sense of most recent , the last in a line.

The history of animals has the shape of a tree. A single root gives rise to a series of branchings as we follow the process forward in time. One species splits into two, and each of those species splits again (if it does not die out first). If a species splits, and both sides survive and split repeatedly, the result may be the evolution of two or more clusters of species, each cluster distinct enough from the others to be picked out with a familiar name the mammals , the birds . The big differences between animals alive nowbetween beetles and elephants, for exampleoriginated in tiny insignificant splits of this sort, many millions of years ago. A branching took place and left two new groups of organisms, one on each side, that were initially similar to each other, but evolved independently from that point on.