Consider the octopus: Around 300 species of this animal inhabit Earth's oceans, ranging in size from under 1 pound (the star-sucker pygmy octopus) to perhaps 600 pounds with an armspan of 30 feet (a monster-sized giant Pacific octopus reported by a Canadian commercial diver in the 1950s; 300 pounds and 20 feet is probably more typical). The octopus has no solid parts except for its beak, and can therefore compress its body and arms into extremely small or narrow places. That allows it to take advantage of various dens where it spends its time, which can be anything from a tide pool to a deep-sea rock crevice. The octopus has eyes, but its primary sensory mechanism is a mix of touch and chemical-based smell or taste, both of which are communicated via the suckers on its arms. The eyes even have a lens-focusing "camera" mechanism similar to that of vertebrates, even though they evolved down a completely separate evolutionary path.
Octopi are generally seen as intelligent animals: They can learn to navigate a maze like a lab rat. Their behavior can be shaped by rewards and punishments, just like ours can. They can differentiate between two familiar environments, as evidenced by their ability to pick out a different reward location in each one. They can learn to unscrew jars to obtain food: Not only is this an example of tool use, but they can even do it when they themselves are trapped in the jar! Researchers also report various octopus "tricks" in the lab, including stealing food from a neighboring tank, turning off lights by squirting ink to short-circuit the electricity, and selectively splashing one particular staff member when they passed by the tank. And 2024 footage from divers off the coast of Israel showed octopi using fish as hunting animals, the same way that humans might use dogs; they even punch wayward fish in their team to keep them on-task! All of these behaviors lead us humans to suspect that the octopus is a fellow conscious being, that there is "something that it is like" to be an octopus.
Of course, we might be wrong in that assumption. I wrote recently about our tendency to attribute a rich internal life to robots, which presumably don't have one. I have previously written about the "zombie problem" in philosophy, and about skeptics like Daniel Dennett who argue that none of us are really conscious -- in other words, that I'm just as mistaken about my own inner life as I am about a robot's. Still, most people do in fact express the belief that they are conscious and aware. Most people extend that same assumption to other people's conscious awareness -- in other words, that our friends and neighbors have their own rich internal lives, rather than walking around as automatons. It's a rare person who doesn't extend the same courtesy to dogs, rabbits, or chimpanzees: We might argue about the degree or type of experience those animals are having, but we generally do assume there is "something that it is like" to be a dog. So, then, by extension, our theory of mind probably extends to octopi. We assume that they, like us, have conscious experiences, and for much the same reasons that we assume our fellow humans also have conscious experiences.
In some ways, however, our assumptions about octopus consciousness require a much greater leap than our assumptions about canine consciousness. To start with, octopi are mollusks. This is about as far as one can get from humans on the evolutionary tree. Our mammalian branch split off from that of the dinosaurs about 300 million years ago. Our nearest common ancestor with the octopus was more than twice that long ago, at 686 million years and in the Proteozoic era (earlier than that, the Earth didn't have features like tectonic plates!). Our last common ancestor was probably some form of worm with a very simple nervous system. Nevertheless, octopi evolved large brains -- about the same percentage of its body mass as vertebrates, although less large than those of mammals. Besides its central brain, the octopus has separate large ganglia or "sub-brains" that control each of its eight arms. The arms together contain nearly twice the amount of neurons as the head does. An octopus arm can still perform various reaching and grasping motions even if it is separated from the main body of the octopus! Philosopher Eric Schwitzgebel writes that octopi are probably the most "alien" intelligent species we are likely to encounter without leaving the planet.
Nevertheless, in a 2011 study that required octopi to maneuver an arm through a dry-air maze (which deprives the arm of its usual chemical senses), the octopus was able to visually coordinate the arm's motion in order to reach its goal. The central brain therefore also has a role in octopus behavior, above and beyond the mental activity that seems to be centered in the individual arms. The central brain may also be involved in learning, and the octopus shows long-term memory as evidenced by its recognition of mazes and personally-disliked lab attendants! Finally, the octopus has neural patterns that approximate REM sleep, at least in the sense that they are more similar to waking activity even though the animal's behavior suggests sleeping. And octopus brains even seem to show left-right dominance of some arms over others, in a manner similar to humans. At a more formal level, Dr. Jennifer Mather has shown that octopus behavior shows mental traits consistent with consciousness such as rich perceptions, awareness of the passage of time, and integration of different types of perceptual input.
If octopi have conscious experiences, what does that imply about our own state of consciousness? First, it's almost certain that octopi do not express themselves in language, unlike dolphins who are the most like us of any ocean-dwelling creature. If octopi don't use language then they also almost certainly don't think in language, which some researchers have characterized as simply subvocal speech. Of course, neither do most of our fellow mammals. In that case, activities like social affiliation and goal tracking are not the result of our inner dialogue, and thoughts do not drive behaviors. This relatively simple observation about the psychology of animals seems to undermine the theoretical basis for cognitive therapy. Octopi, in other words, accomplish everything they do without recourse to a Narrative Mind.
Octopi do, on the other hand, seem to have finely-tuned Intuitive Minds, with the arm-ganglia capable of parallel processing in the same way that our own brains are (at least, in all areas except language!). Do octopi have a single stream of consciousness, or is it multiple in some way? The behavior of a detached arm seems more like a simple stimulus-response arc, without the complex memory and planning activities that go on in the octopus head. It seems likely, then, that the head is where any conscious experience would reside, even though it is a less-dense neurological environment than the arms. Perhaps there is some type of summation of 8 streams of experience into a single octopus consciousness. In the same way, our own Intuitive experiences seem to add up to a single stream of conscious awareness, even as the Intuitive Mind goes on running important functions outside of consciousness. Or maybe we can envision a more alien experience of the world, in which the 8 streams of experience are centrally integrated, but still separate in some ways. We don't think of ourselves as having multiple streams of experience, but in some ways we do, with divided experience between the left and right hemispheres of the brain. Human awareness may be more divided than we usually think.
Part of our unified self-concept likely comes from the fact that humans layer another level of thinking on top of the Intuitive stream of experience -- the Narrative Mind. Yet it doesn't seem that language and reasoning, the things that we often consider the sine qua non of humanity, are really necessary to consciousness. In that, we may be more similar to our far-flung relative the octopus than we seem.
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