Many Minds

• String theories

  Where would our species be without string? It's one of our most basic technologies—so basic that it's easy to overlook. But humans have used string—and its cousins rope, yarn, cordage, thread, etc.—for all kinds of purposes, stretching back tens of thousands of years. We've used it for knots and textiles and fishing nets and carrier bags and bow-strings and record-keeping devices. It's one of the most ubiquitous, flexible, and useful technologies we have. But we haven't only put string to practical purposes. We've also long used it to tickle our minds. My guest today is Dr. Roope Kaaronen. Roope is a cognitive anthropologist and postdoc at the University of Helsinki in Finland. Along with an interdisciplinary team, Roope recently conducted two studies that showcase the centrality of string in human culture. One is on the history and diversity of "string figures” (which are visual designs made with a loop of string held between the hands, often known to English speakers as “Cat's Cradle”). The other study is on the history and diversity of knots. Here Roope and I discuss the deep history of string in human culture. We talk about the seemingly universal spread of string figures across the globe. We zoom in on one string figure in particular—the Jacob's ladder—which seems to be the most widespread string figure of all, despite its complexity. We talk about how both knots and string figures are related to the branch of mathematics known as “topology," and about how knots and string figures have evolved under different constraints. Finally, we discuss what our fascination with string designs might tell us about the human mind. And we lament the fact that much of our string-based cultural heritage is headed—quite rapidly—for extinction. Just a reminder that applications are now open for the 2025 Diverse Intelligences Summer Institute or DISI. If you are an early career researcher and you like this show, you would probably like DISI. Actually, fun fact: our guest today, Roope, is a DISI alum. We met at the Institute a couple years ago and I've followed his work ever since. That should give you some flavor for the people who attend. In any case, for more info, check out disi.org—that’s d-i-s-i. org. Alright friends, on to my conversation with Dr. Roope Kaaronen. Enjoy!   A transcript of this episode is available here.   Notes and links 3:00 – The 2020 paper reporting the use of string by Neanderthals. 8:00 – A paper describing the Antrea Net and its discovery. 10:00 – On the issue of gender bias in the study of textiles, see Virginia Postrel’s book, The Fabric of Civilization. 12:00 – Dr. Kaaronen’s other ethnomathematical projects include work on measurement across cultures.  16:30 – The website of the International String Figure Association. 19:30 – The 1969 paper first introducing the Standard Cross-Cultural Sample.  22:20 – A step-by-step explanation for how to make Jacob’s Ladder. 30:30 – A step-by-step explanation for how to make the Swan. 38:00 – An example of a string figure that uses the Caroline Extension.  40:35 – A video demonstrating the string figure game of Cat’s Cradle, which is played with a partner. 44:30 – A preprint of the knot study by Dr. Kaaronen and colleagues.  45:00 – The website of HRAF—the Human Relations Area Files—is here. 49:00 – A step-by-step explanation for how to make the knot known as the “sheet bend.” 55:00 – An interactive article about what is known about Incan khipus.  59:30 – The “bible of knots” is the Ashley Book of Knots. 1:08:30 – An illustrated article on the so-called Austronesian expansion. 1:16:00 – An image of the ochre stone from 70,000 years ago, found at Blombos cave, featuring net-like imagery. A study finding sensitivity to abstract shapes in humans but not baboons.   Recommendations The Fabric of Civilization, by Virginia Postrel String Figures: A Study of Cat’s Cradle in Many Lands, by Caroline Furness Jayne WhyKnot (YouTube channel)   Many Minds is a project of the Diverse Intelligences Summer Institute, which is made possible by a generous grant from the John Templeton Foundation to Indiana University. The show is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte and with creative support from DISI Directors Erica Cartmill and Jacob Foster. Our artwork is by Ben Oldroyd. Our transcripts are created by Sarah Dopierala. Subscribe to Many Minds on Apple, Stitcher, Spotify, Pocket Casts, Google Play, or wherever you listen to podcasts. You can also now subscribe to the Many Minds newsletter here! We welcome your comments, questions, and suggestions. Feel free to email us at: [email protected].  For updates about the show, visit our website or follow us on Twitter (@ManyMindsPod) or Bluesky (@manymindspod.bsky.social).

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  1:21:28
• The other half of the brain

  Neurons have long enjoyed a kind of rock star status. We think of them as the most fundamental units of the brain—the active cells at the heart of brain function and, ultimately, at the heart of behavior, learning, and more. But neurons are only part of the story—about half the story, it turns out. The other half of the brain is made up of cells called glia. Glia were long thought to be important structurally but not particularly exciting—basically stage-hands there to support the work of the neurons. But in recent decades, at least among neuroscientists, that view has faded. In our understanding of the brain, glia have gone from stage-hands to co-stars.   My guest today is Dr. Nicola Allen. Nicola is a molecular neuroscientist and Associate Professor at the Salk Institute in La Jolla, California. She and her lab study the role of glial cells—especially astrocytes—in brain function and dysfunction.   Here, Nicola and I talk about how our understanding and appreciation of glial cells has changed. We do a bit of Brain Cells 101, reviewing the main division between neurons and glia and then sketching the subtypes within each category. We discuss the different shapes and sizes of glial cells, as well as the different functions. Glia are an industrious bunch. They’re involved in synapse formation and pruning, the production of myelin, the repair of injuries, and more. We also talk about how glial cells have been implicated in various forms of brain dysfunction, from neurodegeneration to neurodevelopmental syndromes. And how, as a result, these cells are attracting serious attention as a site for therapeutic intervention.   Well, it's that time of year again folks. Applications are now open for the 2025 Diverse Intelligences Summer Institute, or DISI. This is an intense program—highly interdisciplinary, highly international—for scholars and storytellers interested in all forms and facets of intelligence. If you like thinking about minds, if you like thinking about humans and animals and plants and AIs and collectives and ways they’re alike and different—you would probably like DISI. For more info, check out disi.org—that's D-I-S-I dot org. Review of applications begins March 1st, so don't dally too too long.   Alright friends—on to my conversation with Dr. Nicola Allen. Enjoy!   A transcript of this episode is available here.   Notes and links 3:00 – Correction: “glia” actually comes from the Greek—not the Latin—for “glue.” 3:30 – See this short primer on glia by Dr. Allen and Dr. Ben Barres. For a bit of the history of how glial cells were originally conceived, see this article on Ramón y Cajal’s contributions to glia research. 10:00 – On the nascent field of “neuroimmunology,” see here. 14:00 – On the idea that “90% of brain cells are glia” see this article by (former guest) Suzana Herculano-Houzel. 18:00 – The root “oligo” in “oligodendrocyte” means “few” (and is thus the same as the “olig” in, e.g., “oligarchy"). It is not related to the “liga-” in “ligament.” 28:00 – On the idea that the glia-neuron ratio changes as brains grow more complex, see again the article by Dr. Herculano-Houzel. 30:00 – See Dr. Allen’s paper on the idea of glia as “architects.” See also Dr. Allen’s paper on the idea of glia as “sculptors.” 33:00 – See Dr. Allen’s paper on the idea of the “tripartite synapse.” 42:00 – A recent paper reviewing the phenomenon of adult neurogenesis.  48:00 –  See Dr. Allen’s recent review of the role of astrocytes in neurodegeneration. 51:30 – A recent article on the roles of APOE in Alzheimer’s.   Recommendations Glia (2nd edition), edited by Beth Stevens, Kelly R. Monk, and Marc R. Freeman   Many Minds is a project of the Diverse Intelligences Summer Institute, which is made possible by a generous grant from the John Templeton Foundation to Indiana University. The show is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte and with creative support from DISI Directors Erica Cartmill and Jacob Foster. Our artwork is by Ben Oldroyd. Our transcripts are created by Sarah Dopierala.   Subscribe to Many Minds on Apple, Stitcher, Spotify, Pocket Casts, Google Play, or wherever you listen to podcasts. You can also now subscribe to the Many Minds newsletter here! We welcome your comments, questions, and suggestions. Feel free to email us at: [email protected].    For updates about the show, visit our website or follow us on Twitter (@ManyMindsPod) or Bluesky (@manymindspod.bsky.social).

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  59:39
• A paradox of learning

  How do we learn? Usually from experience, of course. Maybe we visit some new place, or encounter a new tool or trick. Or perhaps we learn from someone else—from a teacher or friend or YouTube star who relays some shiny new fact or explanation. These are the kinds of experiences you probably first think of when you think of learning. But we can also learn in another way: simply by thinking. Sometimes we can just set our minds to work—just let the ideas already in our heads tumble around and spark off each other—and, as if by magic, come away with a new understanding of the world. But how does this happen exactly? And does it only happen in humans?    My guest today is Dr. Tania Lombrozo. Tania is a Professor of Psychology at Princeton University; she and her research group study learning, reasoning, explanation, belief, and more. In a recent paper, Tania outlines this puzzling alternative form of learning—learning by thinking, as it’s known—and presents evidence that it happens in both humans and AIs.   In this conversation, Tania and I talk about her longstanding work on explanation, and how it led her to study this less-obvious form of learning. We zoom in on four flavors of learning by thinking—learning through explanation, through simulation, through analogy, and through reasoning. We talk about the evidence that machines also learn in this way, and we consider whether animals could, too. We discuss how to resolve the paradox at the heart of "learning by thinking": how it could be that reshuffling old bits of knowledge can actually lead to new understanding. Along the way, Tania and I touch on: chain-of-thought prompting in LLMs, the Reddit community 'Explain Like I'm Five,’ the illusion of explanatory depth, the power of thought experiments, Darwin and Galileo, imagination and rationalization, how psychology and philosophy complement each other, and whether we can also learn—not just by thinking in our proverbial armchairs—but also by writing and talking.   So, happy 2025, friends! We've got some great stuff lined up for the coming year. If you like what we're doing with the show, we would—as ever—appreciate your support. And the main way you can support us is just by helping us get the word out—by telling a friend about us, or a colleague, or a student, or your thousands of social media followers.   Alright, without further ado, on to my conversation with Dr. Tania Lombrozo. Enjoy!   A transcript of this episode is available here.    Notes and links 3:30 – An influential early paper on “chain-of-thought prompting” in Large Language Models. A recent preprint by a team, including Dr. Lombrozo, exploring the cases where “chain-of-thought prompting” actually impairs performance in LLMs. 8:00 – For some of Dr. Lombrozo’s important earlier work on explanation, see here and here. 11:15 – The Reddit community ‘Explain Like I’m Five.’ 13:00 – An early paper on the “curse of knowledge”—the difficulty of ignoring what you know. 19:00 – Dr. Lombrozo’s recent review article on “learning by thinking” is here. Another article of hers on the same topic is here. 20:00 – The original report of the “self-explanation” effect. The original report of the “illusion of explanatory depth.” 30:00 – For a basic description of Galileo’s falling bodies thought experiment, see here. A discussion of this thought experiment by philosopher Tamar Gendler. 38:00 – For analysis of Darwin’s analogy between artificial and natural selection, see here and here. 42:00 – A paper on rationalization by Fiery Cushman.  48:00 – A paper from Dr. Lombrozo’s lab on “need for explanation.” The original paper describing the construct of “need for cognition.” 52:00 – The original report of “framing effects” by Tversky and Kahneman. 54:00 – A paper by Annette Karmiloff-Smith discussing “representational redescription.” 1:02:00 – A recent overview of issues surrounding “explainable” AI.    Recommendations Alison Gopnik, Andrew Meltzoff, & Patricia Kuhl, The Scientist in the Crib Frank Keil, Wonder: Childhood and the Lifelong Love of Science   Many Minds is a project of the Diverse Intelligences Summer Institute, which is made possible by a generous grant from the John Templeton Foundation to Indiana University. The show is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte and with creative support from DISI Directors Erica Cartmill and Jacob Foster. Our artwork is by Ben Oldroyd. Our transcripts are created by Sarah Dopierala.   Subscribe to Many Minds on Apple, Stitcher, Spotify, Pocket Casts, Google Play, or wherever you listen to podcasts. You can also now subscribe to the Many Minds newsletter here! We welcome your comments, questions, and suggestions. Feel free to email us at: [email protected].    For updates about the show, visit our website or follow us on Twitter (@ManyMindsPod) or Bluesky (@manymindspod.bsky.social).

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  1:06:42
• From the archive: The octopus and the android

  Happy holidays, friends! We will be back with a new episode in January 2025. In the meantime, enjoy this favorite from our archives! ----- [originally aired Jun 14, 2023] Have you heard of Octopolis? It’s a site off the coast of Australia where octopuses come together. It’s been described as a kind of underwater "settlement" or "city." Now, smart as octopuses are, they are not really known for being particularly sociable. But it seems that, given the right conditions, they can shift in that direction. So it's not a huge leap to wonder whether these kinds of cephalopod congregations could eventually give rise to something else—a culture, a language, maybe something like a civilization.  This is the idea at the center of Ray Nayler's new book, The Mountain in the Sea. It's both a thriller of sorts and a novel of ideas; it’s set in the near future, in the Con Dao archipelago of Vietnam. It grapples with the nature of intelligence and meaning, with the challenges of interspecies communication and companionship, and ultimately with what it means to be human.  Here, Ray and I talk about how he got interested in cephalopods and how he came to know the Con Dao archipelago. We discuss some of the choices he made as an author—choices about what drives the octopuses in his book to develop symbols and about what those symbols are like. We consider the major human characters in his book, in particular two ambitious researchers who embody very different approaches to understanding minds. We also talk a fair bit about AI—another central character in the book, after all, is a super-intelligent android. Along the way, Ray and I touch on Arrival, biosemiotics, the nature of symbols, memory and storytelling, embodiment, epigenetics, cephalopod camouflage, exaptation, and the sandbox that is speculative fiction.  This episode is obviously something a little different for us. Ray is a novelist, after all, but he’s also an intellectual omnivore, and this conversation, maybe more than any other we’ve had on the show, spans three major branches of mind—human, animal, and machine. If you enjoy this episode, note that The Mountain in the Sea just came out in paperback, with a jaw-droppingly cool cover, I’ll add. I highly recommend that you check it out. One more thing, while I have you: If you're enjoying Many Minds, we would be most grateful for your help in getting the word out. You might consider sharing the show with a friend or a colleague, writing us a review on Apple Podcasts, or leaving us a rating on Spotify or Apple. All this would really help us grow our audience.  Alright friends, on to my conversation with Ray Nayler. Enjoy!    A transcript of this episode is available here.     Notes and links 8:30 – For the review of The Mountain in the Sea in question, see here.  14:00 – Con Dao is a national park in Vietnam. 17:00 – For our previous episode about cephalopods, see here. 19:00 – For a book-length introduction to biosemiotics, see here.   24:00 – A video of Japanese macaques washing sweet potatoes.  26:30 – For discussion of the human case, in which environmental pressures of some kind may have propelled cooperation, see our episode with Michael Tomasello.  29:00 – A popular article about RNA editing in cephalopods.  35:00 – A video of the “passing cloud” phenomenon in cuttlefish. A brief article about the phenomenon. A video showing other forms of camouflage in octopuses. 41:00 – An experimental exploration of the movement from “iconic” to “symbolic” communication in humans.  44:00 – A popular article about the communication system used in the movie Arrival.  49:00 – One source of inspiration for Ray’s book was Eduardo Kohn’s How Forests Think.  1:00:00 – An article on the idea of “architects” and “gardeners” among writers.  1:05:00 – Ray’s story ‘The Disintegration Loops’ is available here. 1:11:00 – Ray’s story ‘The Summer Castle’ is available here.  1:13:00 – A popular article about the phenomenon of highly superior autobiographical memory. An essay about the idea that faulty memory is a feature rather than a bug. 1:18:00 – Ray’s story ‘Muallim’ is available here.   Recommendations Ways of Being, by James Bridle Living in Data, by Jer Thorp   Follow Ray on Twitter.   Many Minds is a project of the Diverse Intelligences Summer Institute, which is made possible by a generous grant from the Templeton World Charity Foundation to UCLA. It is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte and with creative support from DISI Directors Erica Cartmill and Jacob Foster. Our artwork is by Ben Oldroyd. Our transcripts are created by Sarah Dopierala. Subscribe to Many Minds on Apple, Stitcher, Spotify, Pocket Casts, Google Play, or wherever you listen to podcasts. You can also now subscribe to the Many Minds newsletter here! We welcome your comments, questions, and suggestions. Feel free to email us at: [email protected].   For updates about the show, visit our website or follow us on Twitter: @ManyMindsPod.

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  1:25:39
• Your brain on language

  Using language is a complex business. Let's say you want to understand a sentence. You first need to parse a sequence of sounds—if the sentence is spoken—or images—if it's signed or written. You need to figure out the meanings of the individual words and then you need to put those meanings together to form a bigger whole. Of course, you also need to think about the larger context—the conversation, the person you're talking to, the kind of situation you're in. So how does the brain do all of this? Is there just one neural system that deals with language or several? Do different parts of the brain care about different aspects of language? And, more basically: What scientific tools and techniques should we be using to try to figure this all out?   My guest today is Dr. Ev Fedorenko. Ev is a cognitive neuroscientist at MIT, where she and her research group study how the brains supports language and complex thought. Ev and her colleagues recently wrote a detailed overview of their work on the language network—the specialized system in our brain that underlies our ability to use language. This network has some features you might have expected, and—as we’ll see—other features you probably didn't.   Here, Ev and I talk about the history of our effort to understand the neurobiology of language. We lay out the current understanding of the language network, and its relationship to the brain areas historically associated with language abilities—especially Broca's area and Wernicke's area. We talk about whether the language network can be partitioned according to the subfields of linguistics, such as syntax and semantics. We discuss the power and limitations of fMRI, and the advantages of the single-subject analyses that Ev and her lab primarily use. We consider how the language network interfaces with other major neural networks—for instance, the theory of mind network and the so-called default network. And we discuss what this all tells us about the longstanding controversial claim that language is primarily for thinking rather than communicating.   Along the way, Ev and I touch on: some especially interesting brains; plasticity and redundancy; the puzzle of lateralization; polyglots; aphasia; the localizer method; the decline of certain Chomskyan perspectives; the idea that brain networks are "natural kinds"; the heart of the language network; and the question of what the brain may tell us—if anything—about how language evolved.   Alright friends, this is a fun one. On to my conversation with Dr. Ev Fedorenko. Enjoy!   A transcript of this episode is available here.    Notes and links 3:00 – The article by a New York Times reporter who is missing a portion of her temporal lobe. The website for the Interesting Brains project.  5:30 – A recent paper from Dr. Fedorenko’s lab on the brains of three siblings, two of whom were missing portions of their brains.  13:00 – Broca’s original 1861 report.  18:00 – Many of Noam Chomsky’s ideas about the innateness of language and the centrality of syntax are covered in his book Language and Mind, among other publications. 19:30 – For an influential critique of the tradition of localizing functions in the brain, see William R. Uttal’s The New Phrenology. 23:00 – The new review paper by Dr. Fedorenko and colleagues on the language network.  26:00 – For more discussion of the different formats or modalities of language, see our earlier episode with Dr. Neil Cohn. 30:00 – A classic paper by Herbert Simon on the “architecture of complexity.” 31:00 – For one example of a naturalistic, “task-free” study that reveals the brain’s language network, see here.  33:30 – See the recent paper arguing “against cortical reorganization.” 33:00 – For more on the concept of “natural kind” in philosophy, see here.  38:00 – On the “multiple-demand network,” see a recent study by Dr. Fedorenko and colleagues.  41:00 – For a study from Dr. Fedorenko’s lab finding that syntax and semantics are distributed throughout the language network, see here. For an example of work in linguistics that does not make a tidy distinction between syntax and semantics, see here.  53:30 – See Dr. Fedorenko’s recent article on the history of individual-subject analyses in neuroscience.  1:01:00 – For an in-depth treatment of one localizer used in Dr. Fedorenko’s research, see here.  1:03:30 – A paper by Dr. Stephen Wilson and colleagues, describing recovery of language ability following stroke as a function of the location of the lesion within the language network. 1:04:20 – A paper from Dr. Fedorenko’s lab on the small language networks of polyglots.  1:09:00 – For more on the Visual Word Form Area (or VWFA), see here. For discussion of Exner’s Area, see here.   1:14:30 – For a discussion of the brain’s so-called default network, see here.  1:17:00 – See here for Dr. Fedorenko and colleagues’ recent paper on the function of language. For more on the question of what language is for, see our earlier episode with Dr. Nick Enfield.  1:19:00 – A paper by Dr. Fedorenko and Dr. Rosemary Varley arguing for intact thinking ability in patients with aphasia.  1:22:00 – A recent paper on individual differences in the experience of inner speech.   Recommendations Dr. Ted Gibson’s book on syntax (forthcoming with MIT press) Nancy Kanwisher, ‘Functional specificity in the human brain’    Many Minds is a project of the Diverse Intelligences Summer Institute, which is made possible by a generous grant from the John Templeton Foundation to Indiana University. The show is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte and with creative support from DISI Directors Erica Cartmill and Jacob Foster. Our artwork is by Ben Oldroyd. Our transcripts are created by Sarah Dopierala.   Subscribe to Many Minds on Apple, Stitcher, Spotify, Pocket Casts, Google Play, or wherever you listen to podcasts. You can also now subscribe to the Many Minds newsletter here! We welcome your comments, questions, and suggestions. Feel free to email us at: [email protected].    For updates about the show, visit our website or follow us on Twitter (@ManyMindsPod) or Bluesky (@manymindspod.bsky.social).

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  1:32:56

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