Other Minds: The Octopus and the Evolution of Intelligent Life

by Peter Godfrey-Smith

the sea is the original home of the mind, or at least of its first faint forms.

There are two sides to the world that have to fit together somehow, but do not seem to fit together in a way that we presently understand. One is the existence of sensations and other mental processes that are felt by an agent; the other is the world of biology, chemistry, and physics.

Single-celled organisms can sense and react. Much of what they do counts as behavior only in a very broad sense, but they can control how they move and what chemicals they make, in response to what they detect going on around them.

one mechanism registers what conditions are like right now, and another records how things were a few moments ago.

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.

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

A cell’s “environment” is largely made up of other cells, and the viability of the new, larger organism will depend on coordination between these parts.

Most likely, the origin of animals did not stem from a meeting between lone cells who drifted together. Rather, animals arose from a cell whose daughters did not separate properly during cell division.

In an animal like us, a large proportion of the energy taken in as food, nearly a quarter in our case, is spent just keeping the brain running.

The person calling the stroke, the coxswain or “cox,” usually acts as the crew’s eyes and as a coordinator of micro-actions. The same combination can be seen in a nervous system.

In the Cambrian, animals became part of each other’s lives in a new way, especially through predation. This means that when one kind of organism evolves a little, it changes the environment faced by other organisms, which evolve in response.

Nervous systems evolved before the bilaterian body plan, but this body created vast new possibilities for their use.

In the Ediacaran, other animals might be there around you, without being especially relevant. In the Cambrian, each animal becomes an important part of the environment of others. This entanglement of one life in another, and its evolutionary consequences, is due to behavior and the mechanisms controlling it. From this point on, the mind evolved in response to other minds.

The biologist Andrew Parker has argued that the invention of eyes was the decisive event in the Cambrian.

the result of this sensory opening was a “Cambrian information revolution.”

When more is known, decisions become more complicated. (Is the anomalocarid more likely to intercept me if I flee to that hole, or that other one?) An image-forming eye makes possible actions that would be unthinkable without it.

Gehling suspects that scavenging arose, followed by predation. Animals went from feeding on microbial mats to feeding on the dead, and then began hunting the living.

There are about thirty-four animal phyla – basic animal body plans. Only three phyla contain some animals with CABs, and within one of those three, the mollusks, the only animals that count are cephalopods.

All (or almost all) bilaterian animals have some form of memory and a means for learning, enabling past experiences to be brought to bear on the present.

Vertebrate brains all have a common architecture. When vertebrate brains are compared to octopus brains, all bets – or rather, all mappings – are off.

octopuses have not even collected the majority of their neurons inside their brains; most of the neurons are found in their arms.

giant Pacific octopuses can indeed recognize individual humans, and can do this even when the humans are wearing identical uniforms.

the chordate design emerges, with a cord of nerves down the middle of the animal’s back and a brain at one end. This design is seen in fish, reptiles, birds, and mammals.

much of a cephalopod’s nervous system is not found within the brain at all, but spread throughout the body. In an octopus, the majority of neurons are in the arms themselves – nearly twice as many as in the central brain. The arms have their own sensors and controllers.

Even an arm that has been surgically removed can perform various basic motions, like reaching and grasping.

Some cuttlefish have very large brains – perhaps even larger, as a fraction of the body, than octopuses. That is quite a mysterious fact at the moment, and less is known about what cuttlefish can do.

A vast range of movements became possible, but they had to be organized, had to be made coherent. Octopuses have not dealt with this challenge by imposing centralized governance on the body; rather, they have fashioned a mixture of local and central control.

some animals do not integrate their experience nearly as much as we do.

in many animals the eyes are on each side of the head, not the front. The eyes then have separate visual fields, either largely or entirely, and each connects just to one side of the brain.

The special kind of mental fragmentation seen in split-brain humans seems to be a routine part of many animals’ life.

quite complicated processing of visual information – processing that runs all the way from eyes, through brain, to legs or hands – can take place without the subject experiencing any of this as seeing.

The senses can do their basic work, and actions can be produced, with all this happening “in silence” as far as the organism’s experience is concerned. Then, at some stage in evolution, extra capacities appear that do give rise to subjective experience: the sensory streams are brought together, an “internal model” of the world arises, and there’s a recognition of time and self. What we experience, in this view, is the internal model of the world that complex activities in us produce and sustain. Feeling starts there – or, at least, it begins to creep into existence when these capacities creep into existence – in the brains of monkeys and apes, dolphins, perhaps other mammals, and some birds.

When we think of simpler animals as having subjective experience, according to this view, we’re projecting onto them a fainter version of our own kind of experience. This is a mistake because our experience relies on features they just don’t possess.

We can do a lot without consciousness, Dehaene thinks, but some things we can’t do.

What we’ve learned over the last thirty years or so, Dehaene thinks, is that there’s a particular style of processing – one that we use to deal especially with time, sequences, and novelty – that brings with it conscious awareness, while a lot of other quite complex activities do not.

A related family of theories claim that we are conscious of whatever information is being fed into working memory, a special kind of memory which holds an immediate store of images, words, and sounds that we can reason with and bring to bear on problems.

If you think that a global workspace is needed for subjective experience, or a special kind of memory, or some other mechanism along these lines, you’ll hold that only complex brains that are fairly similar to ours can give rise to experiences that feel like something. These brains will probably be found outside of people, but perhaps only in mammals and birds. The result is what I’ll call latecomer views about subjective experience. These views don’t hold that the lights went on in a sudden flash, but they do hold that the “waking up” came late in the history of life and was due to features that are clearly seen only in animals like us.

I treat subjective experience as a broad category and consciousness as a narrower category within it – not everything that an animal might feel has to be conscious. A person might then say that a “global workspace” is necessary for consciousness without it being needed for the most basic kind of subjective experience. Not only is this possible, but I think it’s approximately right.

Many responses to bodily damage that seem to involve pain probably do not.

These results do provide support for a view of pain as a basic and widespread form of subjective experience, one present in animals with very different brains from ours.

the demands of novelty jolt us from unconscious routine into conscious reflection. An octopus’s explorations are sometimes mixed with caution and sometimes with a puzzling recklessness.

The lifespans of different animals are set by their risks of death from external causes, by how quickly they can reach reproductive age, and other features of their lifestyle and environment.

The mind evolved in the sea. Water made it possible. All the early stages took place in water: the origin of life, the birth of animals, the evolution of nervous systems and brains, and the appearance of the complex bodies that make brains worth having.