Other Minds: the Octopus, the Sea, and the Deep Origins of Consciousness by Peter Godfrey-Smith was a fantastic read and probably the most fun, interesting, and thought-provoking book I have read in a long time. The whole time I read the book I couldn’t help but immerse myself in what was currently being discussed, whether it was an encounter with an octopus or a hypothetical oceanic scene 270 million years ago it felt like I was floating in the water the whole time. This book has changed the way I think about the world we live in, and the way I will go about creating my own.

Note that I do not care about the semantics of whether the plural for octopus is octopi or octopuses and for the sake of my own sanity I will be using octopi (it rolls off my tongue nicer). Godfrey, throughout the book, uses octopuses.


I will attempt to summarize each chapter, of which there are eight, into one-to-two paragraphs each. This will do the book a disservice, but it will stop me from going overboard and rewriting the whole book word-for-word.

Chapter 1: Meetings Across the Tree of Life

The first chapter begins by introducing us to Octopolis, an incredibly unique site off the coast of Australia that diver Matthew Lawrence is accredited with the discover of. The site is so unique that since the books publishing, in 2016, only one other similar site also off the coast of Australia has been discovered. Octopolis, and subsequently the second site named Octlantis, are unique because of the sociality found in the octopi there, Octopus tetricus, who are normally thought to be asocial.

Octopolis is the main site of many of Godfrey’s studies and has a whole chapter, chapter eight, dedicated to it. I won’t go into too much detail about the site in either of these chapters since it is not my main reason for reading the book of my main focus behind this review, but both chapters are nevertheless worthwhile reads.

Chapter 2: A History of Animals

In the second chapter Godfrey gives a basic fundamental rundown of evolutionary history, but one where the main focus is the nervous system. Godfrey restates multiple times throughout the book, and makes it very evident in this and the final chapter, that life has an aquatic and oceanic history. This got me thinking very early on about what life might look like on a planet devoid of a centralized ocean.

By the end of the chapter Godfrey has walked us through evolutionary history up to the early Cambrian. Single celled organisms have consumed each other and become the first multi-cellular organisms, senses and nervous systems have evolved, predation has appeared and claimed its first victims, the bilaterian body plan has seen its rise to dominance, complex nervous systems made to deal with complex sensory intake have evolved.

Chaper 3: Mischief and Craft

The third chapter aims to introduce and answer some basic questions about the evolution of intelligence. Godfrey introduces an interesting analogy, comparing the brain to a tool kit for the control of behavior. All tool kits share similarities, like perception, though each tool kit has its own way of incorporating this. Some tool kits are elaborate and expensive, others are simple and cheap. Godfrey says that octopi are intelligent but slow learners, great at adapting to unfamiliar and alien environments.

The later half of the chapter is devoted to the neurobiology of the octopus, introducing the concept of the decentralized nervous system. Octopi nervous systems are, like ours, made of neurons which fire and receive electrochemical signals. When neurons are gathered together and connected and fired in different patterns and with different chemicals they can create more complex behavior and systems with one another, this is the basis of the nervous system. Neurons in invertebrates, like octopi, form a rope-like structure composed of small brain-like knotted ganglia and ropes of neurons which connect them. Octopi do have a centralized brain, located around their stomach (a peculiar position, Godfrey notes, since consumed items could easily impale their brain), which all ganglia communicate to and which can communicate back to them. This central brain can order the ganglia, which are each connected to their own tentacle, to do certain tasks and exhibits a form of basic motor control over them.

Chapter 4: From White Noise to Consciousness

The fourth chapter discusses the evolution of experience, why and how are we conscious. Godfrey introduces a lot of important terms in this chapter, terms which you can find the definitions to later on in this page. Importantly the idea of ‘split brain’ is introduced. Vertebrates have an interesting quirk in their neurobiology where the two halves of the brain are used to process different information, this alone is not that interesting, however when the knowledge that these two halves do not communicate as much in some species as they do in other is applied this becomes much more interesting. Godfrey states that, “subjective experience does not arise from the mere running of the system, but from the modulation of its state, from registering things that matter.”

Everything we understand about the neurobiology of the octopus then has the knowledge previously discussed applied to it. Godfrey quotes works by Hillel Chiel and Randy Beer which compare the octopus to a band, where the central brain is a conductor of jazz players who are inclined to improvisation and will only take so much direction.

Chapter 5: Making Colors

The fifth chapter begins with an introduction to the Giant Cuttlefish, Sepia apama, which Godfrey notes are capable of much grandeur displays than octopi. Godfrey goes into great detail on how cephalopods change their colors, but ends in noting that they are colorblind; lacking in the color-differentiating cells that almost all other animals have. So, then, how are cephalopods such great masters of camouflage? The answer, as Godfrey predicts, lies in a scientific paper that suggests cephalopods like the cuttlefish may be able to see color through their skin using specialized photoreceptive organs.

But, why can an animal that has so much to say communicate so little? To answer this Godfrey introduces baboons, with their complex social troops and soap opera-like lives. Baboons only have 4 sounds which they can make, but are capable of extracting information and assembling complex chronological timelines simply by listening to who and how these sounds are made. On the contrary, Caribbean Reef Squid, Sepioteuthis sepioidea, are documented to have a great many displays they can make but are unable to communicate much information through these displays (As far as science is currently concerned). “On the baboon side, there’s a soap opera life … On the cephalopod side, there’s a simpler social life … but such extraordinary things expressed nonetheless.”

Chapter 6: Our Minds and Others

The sixth chapter is used by Godfrey to ponder on inner speech and its evolutionary purpose. Animals don’t need language for complex internal processing; the baboons serve as an excellent example. Instead, Godfrey suggests that perhaps the Vygotsky way of thinking is correct. Inner speech works to exert executive control over the mind, a way of experimenting without doing or exerting control over whims; a means of System 2 thinking. Godfrey theorizes that perhaps inner-monologue came about as an evolutionary byproduct of efference copies, a way to register what we are trying to say internally became a way to think internally.

Workspace theory, the idea that conscious thought is what allows us to perform novel and deliberate actions that require a ‘workspace’ of integrated senses and memory is introduced. Godfrey notes that Baars, Dehaene, and Naccache believed in workspace theory but also that broadcasting information throughout the brain is how information is made conscious and thus introduced to the workspace; instead, Godfrey says, broadcasting is perhaps simply a side-effect of inner speech. Godfrey proposes the idea that inner speech is how the brain creates a feedback loop, “intertwining the construction of thoughts and the reception of them.” Godfrey shoots down the idea that there is an essential step to subjective experience, but instead introduces the idea that there are multiple evolutionary steps and neurological processes that create subjective experience as we know it.

The chapter ends introducing us to afference, exafference, reafference, reafferent loops, and reintroducing efference copies. Reafferent loops are important here, and Godfrey notes that they are like internal monologue. Octopi cannot see their own patterns like a human can hear themselves talk, and for this reason there can be no feedback loop for an octopus like there can be for a human.

Chapter 7: Experience Compressed

Chapter seven is personally the chapter that I find most interesting, introducing me to many evolutionary ideas that I have pondered on in the past but have never quire fully understood. Godfrey asks why octopi and cuttlefish live such short lives, why do they ‘spontaneously fall apart’? Well, it has to do with evolutionary pressures and genetic mutation. The Medawar and Williams effects work together to create senescence, causing organisms which suffer great predation, like cephalopods, to acquire late-acting mutations and quick reproductive cycles.

Chapter 8: Octopolis

Chapter eight is the final chapter of the book and covers Octopolis. As I briefly mentioned, since the books publishing, another site similar to Octopolis has been discovered, named Octlantis. I won’t explain much about this chapter since it’s not as important to the overall science that I am interested in reviewing here, but nevertheless it is an excellent chapter of the book and I would highly recommend anyone to go read it themself. The chapter offers great insight into the behavior of octopi and the way they interact with their environment. It also presents a great short review of everything discussed in the book and introduces some thought-provoking history on human-ocean interaction.

Final Thoughts

Other Minds by Peter Godfrey-Smith is a must-read in my opinion, I failed to cover a lot of ideas discussed in the book and truly did not do it justice in my summary and must implore you to read it for yourself. While reading the book I attempted to jot down any ideas that came to me and began constructing a sort of ‘check list’ for determining certain factors about life that I would like to apply to my worldbuilding and writing endeavors.

  • All complex animals register primordial emotions like pain, hunger, and thirst. It is not what the organism processes but how it processes them that determines its subjective experience.
  • Not all body plans allow for higher thought by means of reafferent loops. An animal can have a lot to say but very little to hear.
  • How quickly animals age is determined by how much they are predated. An animal with many predators will feel the effects of the Medawar-Williams effect more than an animal with few predators.

Important Terms

Note that any of the definitions for these terms may be incorrect; they are simply what I took the word to mean while reading the book.

  • Extractive Foraging: A theory set forth by Katherine Gibson. Proposes two kinds of foraging, one where organisms specialize on a food that requires little manipulation and can be handled the same in every case, and another (extractive foraging) where the organism must adapt its choices to the circumstances.
  • Embodied Cognition: Psychology theory/movement that poses the idea that many features of cognition are shaped by aspects of an organism’s whole body.
  • Perceptual Constancies: The ability to recognize an object even if it changes. (Ex: A door opening or closing, you still know its a door even though it’s moved or changed in your vision.)
  • Primordial Emotions: Feelings which register important bodily states and deficiencies.
  • Afference: Everything you take in through your senses.
  • Exafference: Sensory changes due to changes in the objects around you.
  • Reafference: Sensory changes due to your own actions.
  • Efference Copy: A strategy employed by organisms to distinguish between reafference and exafference. As the organism moves it sends a signal to the parts of its body that deal with perception so they may compensate for movement.
  • Reafferent Loop: A byproduct of reafference which allows for external information storage. For example, taking a note. You change the world outside of you so that you may take in different sensory information later.
  • Senescence: Natural decay of organisms over time.
  • Medawar Effect: Late-acting genetic mutations are less likely to be bred out of a population because few organisms are likely to ever experience them.
  • Williams Effect: Natural selection will accumulate mutations with good-effects now and bad-effects later.
  • Semelparous: Organisms which reproduce only once in their lifetime.
  • Iteroparous: Organisms which reproduce multiple times throughout their life.
  • Episodic Memory: Memory of particular events.
  • Procedural Memory: Memory of skills.
  • Semantic Memory: Memory of facts.