Metazoa is kind of a sequel to “Other Minds”, Godfrey-Smith’s excellent book about the nature of cephalopod intelligence. Metazoa takes a broader view, and explores the nature of minds in general, and how they’re inextricably linked to the animal way-of-being: having a unified, unitary body that can sense and react to the world around it. It was also an interesting book to read in combination with Sean B. Carroll’s “Endless Forms Most Beautiful” about animal body plans, and how they evolved through the use of gene regulatory networks and a meta-genetic toolkit that we share with all bilaterians.
This author kind of feels like a Carl Sagan of Marine Biology — very clearly trying to understand the world within a Materialist / Naturalist framework (which I appreciate) but without losing a sense of the mystical nature of existence. He’s asking “What kind of thing is a mind?” and “How can that kind of thing arise through evolution and be composed of nothing but a particular collection of matter and energy?” Why does this happen at all? How general or common a phenomenon is it?
A lot of both this book and Other Minds is about highlighting similar features that seem to have arisen both in human / mammalian / vertebrate brains-and-minds, and the almost completely independently evolved brains-and-minds of other very different forms of life. Our family tree split more than half a billion years ago, and our last common ancestor was, by all indications, something like a flatworm.
So it’s kind of crazy that so many high level similarities have arisen — it makes it seem plausible that minds in general are just a kind of thing that matter does sometimes in the universe. Compound and camera eyes, the ability to sense pressure and heat and chemical gradients, to manipulate the world around you, to differentiate between yourself and other things, and the consequences of your actions, and phenomena that are independent of you — to a remarkable degree these phenomena exist in at least 3 big branches of Earth’s phylogenetic tree, mostly independently.
There’s a lot in here that gets at the connection between knowing and doing too, which is something I’ve been thinking about a lot lately, especially in the context of collective action and knowledge at the societal level.
One idea he explored that was interesting was the possibility of more distributed consciousnesses, as in the case of the octopus, which only has about 1/3 of its neurons in a centralized “brain” while the rest are distributed throughout its arms. The arms appear to be semi-autonomous, but also capable of acting in concert with each other and some more directed, centralized purpose when the creature wants to. So does each arm have its own independent or subsidiary consciousness? Do they meld together with each other? Or with the centralized mind when there’s more attention being paid? This seems pretty abstract and hypothetical… except that it turns out we have evidence for this kind of multiplicity of consciousness in humans too!
In some severe cases of epilepsy, the two hemispheres of human brains are surgically separated, and these split-brained folks are still generally able to function well under most circumstances. But when you isolate the sensory input to one side of the brain, things get weird. Like you can recognize an object, but not think of the word that describes it. I’d read about this before, but I hadn’t heard that you can induce this situation non-destructively in people too! It’s possible to put just one hemisphere of the brain under general anesthetic at a time, leaving you with the consciousness of half-a-brain! And it’s still conscious! And the kind of consciousness you have is different, depending on which half is awake! Knock out the side that deals with language, and every single word you know is suddenly just on the tip of your tongue… Part of me (which part?!) would honestly love to have this experience. What does the transition from one-sided consciousness to two-sided consciousness feel like? Waking up that other half of yourself?
Also wild: it turns out that this is how dolphins sleep! One hemisphere at a time. They’re never completely asleep. Also, it seems like many, many different kinds of minds need to sleep, and seem to dream!
Another thing I’d never realized is that there are macroscopic patterns of electrical activity in the brain. Not just cascades of neurons firing, but waves of coordinated electrical flow — a spatially oriented and temporally organized cascades. Almost like a clock cycle in a CPU, and operating at more than one frequency. It reminded me of a 1996 experiment by Adrian Thompson in which circuits were allowed to evolve toward some end in field programmable gate arrays (FPGAs), and it was found that even some disconnected elements of the circuits were necessary for them to function — because they had evolved to take advantage of analog electromagnetic coupling within the computer (more anecdotes here)!
I love these long rambling explorations of some thread of our evolution. The book gave me a deeper appreciation for what it really means to be an animal in the general sense — like in a way that would make it possible to recognize the animal way-of-being in another entirely separate biosphere. It also made the idea of Other Minds more generally in the universe seem more likely to me. Will they develop radio telescopes and space ships? Maybe not, but I find it even hard now to imagine a Universe where Earth is the only home of sensitive, evaluative, coherent selves. I mean if hermit crabs can weigh several different pros and cons in whether or not they should change shells, and then make a decision, why not?
It also got me thinking about these other general ways-of-being that have evolved on Earth. Plants and Fungi seem like the other two obvious ones. The stationary light harvesters, and the disassemblers. What other strategies for macroscopic life exist out there? How often do the different strategies combine with each other? How prevalent are the different strategies? Is it common to get a planet that only has plants and fungi without animals? Or is the animal way-of-being irresistible to life? I want to read The Hidden Life of Trees (plants) and Entangled Life (fungi) for analogous takes on these other branches of our biosphere.
Also: what other kinds of hardware do these underlying strategies play out on? We happen to have cells made of lipid bilayers, and we use them to construct electrical networks using ion channels that influence each other and cause cascades of charge to flow. But surely there are other ways of evolving the same functionality. Are there animals that have fiber optic nerves? That transmit information internally using light instead of electrochemical systems? How does that affect their subjective experience? Are there light-harvesting-beings that make use of harder radiation? UV or X-rays? Or is it just too hard to maintain an ordered substrate with that much energy flowing through you in destructive packets?
At the very end of the book he briefly considers the idea of “artificial” minds — whether based on what we know about how animal minds are composed, we should expect to be able to create something similar in computers. Obviously the hardware is really different, and so the physical kind-of-thing that animal minds are wouldn’t be replicated, but it felt to me like he was too dismissive of the possibility just on the basis of that difference. The pulsing waves of electromagnetic fields that animal minds generate and are bathed within seem too orderly and ubiquitous to be an accident, and they wouldn’t exist in the same way for an artificial mind, but is it so crazy to think that we could figure out (or evolve) another system that would play the same regulatory or other role that those fields play in us?
In any case, plenty of good food for thought.
One thought on “Metazoa by Peter Godfrey-Smith”