Other Minds
The Sea and The Deep Origins of Consciousness
By Peter Godfrey-Smith
Rating | |
Originally published | Dec 6, 2016 |
Tags | Nonfiction Science Philosophy |
Started | Jan 17, 2020 |
Finished | Jan 21, 2020 |
This book investigates why octopus, squid, and cuttlefish (and related animals) have such complex nervous systems and, related to that, express some very complex behavior even though they branched from humans very long ago in the evolutionary tree
Origins of Life, Humans, and Cephalopods
"Because our most recent common ancestor was so simple and lies so far back, cephalopods are an independent experiment in the evolution of large brains and complex behavior. If we can make contract with cephalopods as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over, This is probably the closest we will come to meeting an intelligent alien" (9)
The author aims to learn more about subjective experience and consciousness and perhaps to draw a kine between them
"The chemistry of life is an aquativc chemistry. We can get on land only by carring a huge amount of salt water around with us."(19)
"Evolution has tranformed cell-to-cell signaling from an activity in which cells simply broadcast their signals to whoever os close enough and istening into someting different: an organized netowk." (23)
"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 the other mind" (36)
"meeting an octopus is, in many ways, the closest we're likely to get to meeting an intelligent alien. Yet it's not really an alien; the Earth and its oceans made us both." (200)
Understanding Perception
"Two forms of control are working in tandem: there is the central control of the arm's overall path, via the eyes, combined with a fine-tuning of the search by the arm itself" (69)
"Some animals do not integrate their experience nearly as much as we do" (84)—rather, cognition is more distributed
Birds can learn tasks with only one eye being used and in the brain they "did not show any 'inter-ocular transfer' at all. What seemed to be a skill learned by the whole bird was in fact available to only half the bird" (85)
Some with extreme cases of epilepsy exhibit this "split-brain" behavior though it is very common in some species (namely birds)
"To some degree, unity is inevitable in a living agent: an animal is a whole, a physical object keeping itself alive. But in other ways, unity is optional, an achievement, an invention." (87)
There's no reason to holistically understand things if instead a subset of you can just react to stimulus; this is the difference between the ventral stream which deals with "categorization, recognition, and description of objects" and the dorsal stream which deals with "real-time navigation through space" (88)
This muddles how we understand "sight"
"a frog does not have a unified representation of the world, and instead has a number of separate streams that handle different kinds of sensing" (89)
In the case of humans, "at some stage in evolution, extra capacities appear that do give rise to subjective experience: the sensory streams and brought together, an 'internal model' of the world arrises, and there's a recognition of time and self" (90)
Primordial emotions: "it seems possible that an animal might feel pain or thirst without having an 'inner model' of the world, or sophisticated forms of memory" (93)
Octopuses exhibit perceptual constancies: "abilities an animal has to re-identify objects despite changes in viewing conditions—distance, lighting, and so on" (99) and can perform complex navigation tasks (for example, traversing a large area in a circle and returning to the same point); "our most recent common ancestor—a worm-like creature in the Ediacaran—almost certainly had none of these skills" (100); we independently evolved similar skills
Many actions in octopuses are distributed
They can change skin color: "Neurons reach from the brain through the body into the skin, where they control muscles. The muscles, in turn, control millions of pixel-like sacs of color...stretch the sac to make its color visible, or relax it for the opposite effect." (109) This has an ensemble effect with reflecting cells. They can match their surroundings but interestingly tend to be color-blind. (110-119)
Their skin can sense light and produce a response → can mimic colors behind them rather than merely reflecting or can do things that go way beyond any biological function
Very different from primates which have ~ simple language but complex interpretation: "Here we have very powerful signal production system, but most of what is said is going unnoticed"
"Evolution is not heading anywhere, not toward us or anyone else. But I can't resist seeing, in both animals, an unfinished quality. They are both animals with a one-sidedness in their vision of the fundamental signaling duality, the interlocking roles of sender and receiver, producer and interpreter. On the baboon side, there's a soap opera life, frantic and stressful social complexity, and a little means to express it. On the cephalopod side, there's a simpler social life, hence less to say, but such extraordinary things expressed nonetheless." (133)
"A person is just a bundle or collection of images and feelings, 'which succeed each other with an inconceivable rapidity, and are in a perpetual flux and movement.'" (137)
We have "inner speech" which "makes possible organized thought" (139); "very complex things go on inside other animals without the aid of speech" (141) → language not needed for complex thought
"Language provides a medium for the arrangement and manipulation of ideas"
Inner speech is "a means for System 2 thinking"—"Inner speech gives us a way of performing actions in the right order...and exerting top-down control over habits and whims" (146)
"We start to deal with a task consciously when our habits break down, or can't be applied, and we have to do something new." Specifically, "broadcasting information throughout the brain is what makes that information conscious" (150). "Inner speech is a way your brain creates a loop, intertwining the construction of thoughts and the reception of them." (151) → "higher order thought" about what is going on rather than just sensing and acting
"The nervous system arose through one internalization of sensing and signaling, and the internalization of language as a tool for thinking was another. In both cases, a means of communication between organisms became a means of communication within them." (153)
In the case of cephalopods, "Their expressive medium, colors and patterns, does not lend itself to complex loops...The animal can't see its own patterns in thew ay a person can hear what they say...Cephalopod displays have enormous expressive power, but as long as we're looking at a single animal, rather than a pair or a group, these displays are not embedded in a lot of looping feedback, and perhaps could never be. The human case—an extreme case—suggests that the opportunities associated with reafference help to drive the evolution of a more complicated mind." (157)
Death
For octopuses, "What is the point of building a large nervous system if your life is over in a year or two?" "What is the point of investing in a process of learning about the world if there is almost no time to put that information to use?" (160)
"Why do some organisms live for dozens, hundreds, or thousands of years while others, in the natural course of events, do not see even a single year pass? Death from accident or infectious disease is no puzzle, the puzzle is death from 'old age.'" (162)
"An automobile's original parts will indeed wear out, but an adult human is not operating with his or her original parts. We are made of cells that are continually taking in nutrients and dividing, replacing old parts with new ones." (162)
"At the level of cells there is the possibility of indefinite renewal. But something about the kinds of objects we are—the kinds of collections of cells we are—gives us and other animals a relation to aging that is different from that of other living things." (163)
Mutation-selection balance: "bad mutations of a gene are being weeded out just as quickly as they are being introduced" (166); however many animals reproduce or die before old-age actually impacts them → "the 'selection pressure' against a late-acting harmful mutation is very slight" (166) → "the gene pool of the population will come to contain a lot of mutations that have harmful effects on long-lived individuals." "It will appear to have been 'programmed to decline,' because the effects of those lurking mutations will appear on a schedule. The population has begun to evolve aging." (166-167)
"But things are different if the few individuals who do succeed in reproducing when they are very old can have very large numbers of offspring. This is not true of us, but it is true of trees." (168)
Everything comes down to short term versus long term tradeoffs
"Why should an organism devote all it's resources to one brood, or one breeding season? Much depends, again, on the risk of death by predation or other external causes—especially on how this risk changes over an animal's lifetime. Suppose in some animal the juvenile stage is risky, but once you get to be an adult, you can expect to live for a while without being eaten. Then it makes sense for adults to reproduce more than once...If, on the other hand, the adult life stage is very risky, it might make more sense to 'go for broke' as soon as you get to a stage where you can breed." (171); "If you spend less now to save something for later, that will do you no good if animals of your kind have little chance of making it to the next breeding season" (172)
This philosophy explains the octopus's situation which before seemed paradoxical
"Certainly there has been a temptation to think that octopuses, in particular, have 'too much' brain for animals living such brief and asocial lives" (195)
"once you have a larger nervous system, this makes it worthwhile to further expand the body's possibilities." "The loss of the shell also had another effect: it made the animals much more vulnerable to predators...That put a premium on the evolution of wiles and camouflage." (173)
"An octopus can't expect to live a long time, especially as they must be active predators themselves...This vulnerability makes them ideal candidates for the Medawar and Williams effects to compress their natural lifespan" (173)
A Plea for Protecting the Environment
Overfishing and chemical change via acidification are huge problems (201-202)
Gives an example of a honeybee population which failed due to human-caused changes to their environment: "Eventually a critical point was reached, and honeybee colonies just started to fail. They failed dramatically—visibly—not because some sudden pest had swept through, nut because their capacity to absorb the stresses had run out." (203)
For the ocean, "This sphere of biological creativity is so vast that for centuries we could do whatever we liked to it and have little impact. But now our capacity to stress its systems is much greater." (203)
"There are many reasons for us to appreciate and care for the oceans, and I hope this book has added one. When you dive into the sea, you are diving into the origin of us all." (204)
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