The Octopus: A Case Study in Alien Intelligence
What these evolutionary outliers can teach us about alternative minds
When we imagine aliens, we often picture the little green men of retro 1950s sci-fi. Popular depictions of intelligent extraterrestrials have somewhat diversified since then, but it’s still difficult to escape the classic humanoid form. According to human portrayals, most sentient and civilized species seem to have something resembling a head, where — presumably — they do a majority of their thinking (consider aliens in Star Wars, Star Trek, Avatar, ET, X Files, District 9, etc). This makes sense: nearly all of our experiences with intelligent species are with those who process information in a centralized nervous system. Humans — as well as other relatively intelligent animals such as monkeys, dogs, whales, pigs, and birds — follow this template. But all of these species shared an evolutionary history, and a single planet upon which they evolved. Why should we assume that sentient aliens, who may hail from worlds unfathomably different from our own, will have anything in common with us?
Maybe we need to search for weirder examples of intelligent organisms. All of earth’s life has the same origin — we all share basic cellular structure, genetic code, etc — so it is difficult for us to find creatures that are completely detached from our roots. But there may be one species that can serve as a model of alternatively structured intelligence: the octopus. These strange animals invite us to consider forms of cognition beyond our own narrow, anthropocentric experience.
What is Intelligence and Who Has It?
It’s difficult to come up with one universal definition of intelligence. When studying animal cognition, scientists have often loosely defined it as the ability to solve novel problems, learn from experience and adapt to new situations. Some animals may be highly suited to their environments and able to deal with challenges that commonly arise, but it is flexibility in facing new problems that sets a few species apart. For example, dogs can be trained to successfully carry out a wide variety of tasks including acting as service animals for the disabled and detecting explosives, drugs or diseases via scent; chimpanzees can learn sign language; some African grey parrots can name and categorize objects and even count items.
Octopuses are similarly impressive. They can complete mazes and challenges requiring them to do things like unscrew jar tops; they’ve been known to turn off lights by squirting water at them; they are infamously escape artists, sneaking out of tanks and occasionally causing other types of mischief; they can recognize and remember individual human faces; they have sometimes been observed using tools in the wild, such as carrying around coconut shells for use as portable shelters. These behaviors are rendered even more notable when we consider that cephalopods are most closely related to creatures such as snails and clams. Though defining exactly how intelligent octopuses are can be challenging, it’s clear that they possess more impressive cognition than other invertebrates, and even many vertebrates.
Evolution: Divergent and Convergent
They may be smart, but just how closely related are octopuses to us humans? Let’s consider humanity’s evolutionary history. Birds, some of whom (as mentioned above) have remarkable cognitive abilities, can serve as a point of comparison. The common ancestor of mammals and birds was an early amniote, likely a small reptilian, lizard-like animal. While not a creature we would consider particularly intelligent, it did possess a nervous system structure that we recognize: most information processing and decision-making happened in a centralized brain. From this common ancestor, the evolutionary paths of humans and birds diverged relatively recently, around 310 million years ago. But to find the last common ancestor of octopuses and humans, we have to go much further back: more than 550 million years. This ancient relative was a primitive flatworm. Though we share certain characteristics with octopuses that were passed down from our shared worm ancestor (the general structure of cells, the genetic code, certain genes, etc.), essentially any feature that the flatworm did not possess cannot be considered homologous between octopuses and humans. In other words, any intelligence beyond the level of a flatworm is something that evolved independently in both species, shaped by our wildly different environments. The fact that octopuses and humans both demonstrate notable problem-solving ability and cognitive flexibility is an example of convergent evolution, the concept of similar traits evolving independently in different lineages.
It’s both the evolutionary distance between humans and octopuses as well as the remarkably different habitats in which we evolved that make the cephalopod a good case study in alternative forms of intelligence. Not to mention, octopus nervous systems are dramatically different from ours and from those of any other intelligent animal on earth.
The Decentralized Mind
In humans, nearly all information processing and decision making occurs in the brain. Even the octopus nervous system has a degree of centralization: the brain has some neuronally dense regions such as the vertical lobe, which is responsible for learning and memory. It seems that there can be an advantage to keeping things compact: centralization of nervous systems has evolved independently at least five times in different lineages. This makes sense — neuronal signaling is fast, but not THAT fast. Centralization offers advantages in processing speed, especially for more sophisticated cognitive operations, since neurons can be located in closer proximity. It also reduces the resources needed to grow and maintain long neuronal connections over large distances. But depending on the body structure and lifestyle of an animal, there may be advantages to decentralization as well.
The octopus central brain is still responsible for high-level decision making and learning, but it forms a relatively smaller part of the nervous system than in vertebrates. More than two-thirds of an octopus’ ~500 million neurons are outside the central brain, and most of these neurons — around 350 million of them — are in the arms. Octopus arms communicate with each other via a ring of nerves as well as nerve cords that connect arms across the body, allowing them to coordinate without needing to involve the central brain. Relatively small numbers of nerves connecting the arms to the brain further suggest that much of the sensory and motor processing occurs peripherally. This likely allows octopus arms to react more quickly to their environment than they would be able to if the central brain were in charge of all information processing.
This nervous system architecture is drastically divergent from what we see in humans or other intelligent animals, where the brain is the clear cognitive center. It’s evident that even beings with vastly different systems of information processing can still solve complex problems and behave in ways that we would consider intelligent.
The differences between octopuses and humans also raise questions about the subjective experience of being an octopus. What is this like? Their conscious experience, if it exists, may be fundamentally different from our own. Some researchers have proposed that octopuses may have multiple centers of subjective experience, potentially even having separate “selves” associated with each arm. While this remains speculative, it highlights how profoundly alien the octopus mind and psychology may be compared to ours.
A Model of Alien Intelligence
Fringe theories have sometimes suggested that octopuses may be of extraterrestrial origin, carried to earth on meteors (a version of the idea of panspermia). Though these myths lack scientific merit, they certainly appeal to the popular imagination. Occasional portrayals of aliens in pop culture also resemble octopuses or other cephalopods (Cthulhu, the martians from War of the Worlds), though these are often shown as monsters rather than benevolent, civilized beings.
There is indeed an alien quality to these creatures (not only do they have eight arms, but they can also change color and texture and release ink), and they may provide a useful example of alternative architectures for cognition. Yet octopuses might represent just one of many possible structures of information processing that we could encounter in hypothetical extraterrestrials. The reality of alien intelligence would likely be even stranger and more difficult for us to comprehend, having evolved in unimaginably different environments. Aliens might live in conditions that seem incompatible with life as we know it, like Earth’s extremophiles; they might have alternative biochemistries, with solvents such as sulfuric acid or methane instead of water; they could have exotic modes of reproduction and inheritance that bear little resemblance to our DNA-based system.
The science fiction film “Arrival” presents a thought-provoking example of an alien species with a radically dissimilar form of intelligence. The extraterrestrial beings in the film perceive time in a non-linear fashion, and their language reflects this foreign conceptualization of reality. Their circular logograms hint at a mode of thinking that is initially almost incomprehensible to the human characters.
Octopuses can serve as an earthly example of why humanity should be humble and not immediately resort to anthropocentric thinking. We should be cautious about projecting our own cognitive biases and expectations onto alien minds; they might operate in ways that defy our preconceived notions of intelligence and consciousness. The subjective experience of an alien with a distinct cognitive architecture could be so foreign to us that we would have difficulty recognizing it as a form of intelligence at all. This might not mean, however, that these creatures are not sentient or conscious. Perhaps we’ll need to broaden our conception of intelligence.
Beyond Biology
While alien life forms have long starred in speculative sci-fi, synthetic intelligence has also been a persistent theme in the genre. Humanity’s fascination with AI is obvious, from Asimov’s writing to 2001: A Space Odyssey to the film Her. Recent attention to the rapid development of AI has led to increased debate about when artificial general intelligence (AGI) might arise and what form it might take. The classic Turing test now seems obsolete: large language models have already passed it, but nearly all scientists agree that no existing AI can be considered true AGI. This highlights how much we already struggle to recognize intelligence (or the lack thereof), especially in forms different from ourselves. As technology further advances — and the specter of approaching AGI looms larger — we may be forced to question previous assumptions. Considering what we can learn from octopuses (and theoretical aliens), we might have to expand our idea of what a mind is. (This is a concept much more deeply explored by Michael Levin in this article.)
A Lesson in Cosmic Humility
If earthly life forms such as octopuses can be so different from us, we likely cannot begin to fathom the forms that extraterrestrial intelligence might take. The physical structure of information processing may vary widely among alien species, and the experience of consciousness and psychology of intelligent beings is probably even more diverse. Humans often struggle to empathize with others of the same species; bringing ourselves to recognize and understand foreign minds, whether biological or synthetic, is an even greater challenge.
Maybe cephalopods — weird, goofy, and clever deep-sea creatures that they are — can remind us to stay humble. Humanity’s place in the universe is infinitesimally small, and we’re likely not alone in the cosmos. Our understanding of intelligence and other minds is limited by the finite scope of our own. By admitting our limitations and embracing this cosmic perspective, we can keep our imagination open and better appreciate the beauty of the unknown.
Thanks to A.K. Schnell and Mesa Schumacher for generously granting me permission to use their images.
