The shaman with a thousand faces
Many Minds
When you hear the word "shaman," I'm guessing a web of associations starts to form in your mind. Perhaps you imagine strange ceremonies and strong substances; maybe you think of an earlier time when magic and superstition reigned. But shamanism is not just some relic of the past, or a curio from exotic lands. It's part of our present, and it will almost certainly be part of our future. This is because the roots of shamanism lie within us all. My guest today is . Manvir is an Assistant Professor of Anthropology at the University of California, Davis and to The New Yorker. He's also the author...
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Varieties of childhood
Many Minds
Childhood is a special time, a strange time. Children are adored and catered to—they're given their own menus and bedrooms. They're considered delicate and precious, and so we cushion them from every imaginable risk. Kids are encouraged to play, of course—but very often it's under the watchful eye of anxious adults. This, anyway, is how childhood looks in much of the United States today. But is this the way childhood looks everywhere? Is this the way human childhoods have always been? My guests today are and . Dorsa is an Assistant Professor of Psychology & Neuroscience at Duke...
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Science, AI, and illusions of understanding
Many Minds
AI will fundamentally transform science. It will supercharge the research process, making it faster and more efficient and broader in scope. It will make scientists themselves vastly more productive, more objective, maybe more creative. It will make many human participants—and probably some human scientists—obsolete… Or at least these are some of the claims we are hearing these days. There is no question that various AI tools could radically reshape how science is done, and how much science is done. What we stand to gain in all this is pretty clear. What we stand to lose is less obvious,...
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The primeval soil of play
Many Minds
Puppies wrestling and mock-biting each other. Toddlers playing hide and seek. Kittens pouncing—repeatedly—on a toy mouse. You've no doubt looked on at scenes like this with amusement. And you've no doubt seen some of those viral videos—of ravens sledding down hills, of bumble bees playing with balls. All these moments make us smile, maybe even giggle. But the scientific questions they raise merit serious attention. Where do we see play in the animal kingdom? Where do we not? What functions does play serve? Do we—and many other creatures—have an elemental need for play? My guest today...
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The big five and beyond
Many Minds
If you've heard anything about the study of human personality, you've probably heard about the “big five.” This is a framework that attempts to characterize human personality in terms of five broad factors or dimensions—neuroticism, extraversion, openness, conscientiousness, and agreeableness. The big five framework has been enormously influential, generating heaps and heaps of data, and study after study on the stability of personality, on the factors that shape our personalities, on how our personalities predict success and satisfaction. But is the big five really the best we can do?...
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Philosophers on psychedelics
Many Minds
Some call it the "psychedelic renaissance." In the last decade or so, interest in psychedelic drugs has surged—and not just among Silicon Valley types and psychiatrists and neuroscientists. It's also surged among a stereotypically soberer crowd: academic philosophers. The reasons are clear. With their varied and sometimes transformative effects, psychedelics raise ethical questions, epistemological questions, metaphysical questions, questions about the nature of experience and the nature of the mind. My guest today is . Chris is a philosopher of cognitive science at the University of Western...
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The cuttlefish and its coat of many colors
Many Minds
We humans have a hard time becoming invisible. For better or worse, we're basically stuck with the skin and body we have; we’re pretty fixed in our color, our shape, our overall appearance. And so we're fascinated by creatures that aren't—creatures that morph to meet the moment, that can functionally disappear, that can shape-shift on a dime. And no creatures are more skilled, more astonishing, more bedazzling in their abilities to do this kind of thing than the cephalopods. But how do they do this exactly? What's going on in their skin? What's going on under their skin? And what's going...
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Life, free energy, and the pursuit of goals
Many Minds
You've probably come across the "free energy principle." It's become one of the most influential ideas in the broader cognitive sciences. Since the neuroscientist Karl Friston first introduced it in 2005, the theory has been fleshed out, extended, generalized, criticized, and cited thousands and thousands of times. But what is this idea, exactly? What does it say about the nature of brains and minds? What does it say about the phenomenon of life itself? And is anything that it says really that new? My guest today is . Kate is a philosopher at the University of Edinburgh and the author of the...
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Universal emotions in fact and fiction
Many Minds
Are human emotions universal? Or do they vary from one place to the next and from one time period to the next? It's a big question, an old question. And every discipline that's grappled with it brings its own take, its own framings and forms of evidence. Some researchers appeal to cross-cultural experiments; others turn to neuroimaging studies or conceptual analysis. Some even look to fiction. My guest today is , an Associate Professor of English Literature at Arizona State University. Brad is the author of a new book, ; in it he maps the landscape of debate around this long-contested topic....
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From the archive: Fermentation, fire, and our big brains
Many Minds
Hi friends, We're taking care of some spring cleaning this week. We'll be back in two weeks with a new episode. In the meantime, enjoy this favorite from our archives! - The Many Minds team ––––––––– [originally aired February 22, 2024] Brains are not cheap. It takes a lot of calories to run a brain, and the bigger your brain, the more calories it takes. So how is it that, over the last couple million years, the human brain tripled in size. How could we possibly have afforded that? Where did the extra calories come from? There's no shortage of suggestions out there. Some say...
info_outlineNeurons 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.
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