From the archive: Philosophers on psychedelics
Many Minds
Hi friends! We're taking a bit of a summer pause. We will be back soon—in the meanwhile, enjoy this listener favorite from our archives! ----- [originally aired May 14, 2025] 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,...
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The origins of Darwin's ideas
Many Minds
No discipline, no sphere of intellectual life, has been untouched by the work of Charles Darwin. He died in 1882 but his ideas are very much alive; they're now central to how we understand the natural world, the human mind, non-human minds, plants, biogeography, morality and emotion, culture, language, and more. But where did his ideas come from? How did they grow out of his travels, his social circle, his hobbies, his particular cast of mind? My guest today is . Janet is Professor Emerita at Harvard University in the department of the History of Science. She is perhaps best known for...
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The sparkling deep
Many Minds
It’s tempting to see bioluminescence as an oddity, one of those rare eccentricities of life on earth. And, on land, maybe that’s true. But our planet is mostly water, and out in the open ocean bioluminescence is utterly commonplace. Creatures of all shapes and sorts sparkle and glow, glitter and pulse. But what are these displays for? Why did they evolve? How did light become the currency of the deep? My guest today is . Sönke is a Distinguished Professor of Biology at Duke University, where he and his research group study the visual ecology of the ocean. He’s the author of...
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Is Man the Hunter just a myth?
Many Minds
There's a story about of our past that you know well. It goes like this: At some point earlier in human evolution, we started to hunt. Men in particular—perhaps channeling some deep-seated aggressive impulses—began to seek out big game. This new food source, this bonanza of calories, was what allowed our brains to expand. It changed our bodies and our societies and sent our species off on a whole new track. In short, Man the Hunter made us human. This story—told in different versions, with different points of emphasis—has circulated for decades. It's been debunked and revived, rejected...
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Babies, dogs, and the riddles of word learning
Many Minds
It's kind of astonishing, really, that kids ever learn words. Each one poses a little riddle. Does this sound string refer to a person? A category of things? Or maybe some other feature of the blooming, buzzing world? And yet word learning happens. In fact, we now know it begins earlier in infancy than we realized. And we now know, further, that dogs (or at least some dogs) understand words as well. So how does this happen? What do babies and dogs really know about words? And how might we go about figuring this all out? My guests today are and Dr. Claudia Fugazza. Elika is an Associate...
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The inner life of the hand
Many Minds
Newton saw in the human hand proof of the divine; Darwin saw a key to our species' success. Many others, too, have described the hand in hyperbolic terms, as a paragon of design, a cornerstone of human uniqueness, an engine of our achievements. But what makes the human hand so powerful? Is it the proportions of the fingers? Is it the opposability of the thumb? Or, could it be none of this? Could it be that the real power of our hands lies—not in the physical design—but elsewhere, out of sight? My guest today is . Matt is Professor of Cognitive Neuroscience at Birkbeck, University of...
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From the archive: The cuttlefish and its coat of many colors
Many Minds
Hi friends! We're skipping a beat to take care of some spring housekeeping tasks. We will be back in May! In the meanwhile, enjoy this listener favorite from our archives! ----- [originally aired April 30, 2025] 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,...
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Illuminating cave art
Many Minds
Deep in our past, in the dark depths of caves, our ancestors did something strange and beautiful. Working by firelight, some doodled little designs. Others made hand stencils. Some saw a bulge of rock, or a crack in the wall, and thought to turn it into a horse or a bison. Why did they make this art? What did it mean to them? Who were these artists? These questions are old—very old—but thanks to new methods and new interpretive frameworks, archaeologists are beginning to see them in a new light. My guest today is . Izzy is an archaeologist at Aarhus University in Denmark,...
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What can AI teach us about the mind?
Many Minds
Everyone is talking about AI these days. Often these conversations are about how AI might upend education, or work, or social life, or maybe civilization itself. But among cognitive scientists and psychologists the conversation inevitably drifts toward other questions. What does this latest generation of AI tell us about the human mind? Is it putting old ideas and theories to rest? Is it ushering in new ones? Will AI—in other words—also upend cognitive science? My guests today are and . Mike is a Professor of Psychology at Stanford University, where focuses on language learning and...
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Mutualisms all the way down
Many Minds
No one is an island. We all depend on each other in critical, often tangled ways. And when I say "we" and "each other" I don't just mean humans. Yes, we humans rely on other humans. But we also rely on bees, yeasts, dogs, bacteria, and countless other creatures big and small. These interspecies dependencies—or mutualisms, as biologists call them—have deflected and inflected our history. And there's no doubt they will also inflect our future. My guest today is . Rob is Professor of Applied Ecology at North Carolina State University, where he studies the creatures and ecologies all...
info_outlineIt’s tempting to see bioluminescence as an oddity, one of those rare eccentricities of life on earth. And, on land, maybe that’s true. But our planet is mostly water, and out in the open ocean bioluminescence is utterly commonplace. Creatures of all shapes and sorts sparkle and glow, glitter and pulse. But what are these displays for? Why did they evolve? How did light become the currency of the deep?
My guest today is Dr. Sönke Johnsen. Sönke is a Distinguished Professor of Biology at Duke University, where he and his research group study the visual ecology of the ocean. He’s the author of a number of books: most recently Into the Great Wide Ocean, about life in the pelagic realm, and The Radiant Sea, a photographic tour of bioluminescence and color, written in collaboration with Dr. Steven Haddock.
Here, Sönke and I talk about the open ocean: the most common habitat on our planet, yet one that many people will never experience. We consider the curious distribution of bioluminescence— rare on land, exceptionally prevalent in the ocean, and all but absent in freshwater. We talk about how bioluminescence seems to have evolved—many, many times over in fact. We survey the functions of making light in the deep—from counter-illumination to courtship to revenge. Finally, we consider what Sönke takes to be the biggest remaining puzzle about bioluminescence at sea.
Alright friends, if you’re enjoying Many Minds, we ask (humbly) if you would think about rating us, reviewing us, leaving us a comment, boosting us on social media, or perhaps haranguing your friends—relentlessly—until they give us a listen.
Without further ado, onto my conversation with Dr. Sönke Johnsen. Enjoy!
Notes
3:30 – The scientific report by Dr. Johnsen and colleagues describing the bioluminescent octopus, Stauroteuthis syrtensis.
12:00 – A popular article on the bristlemouth. The article reports a scientist's estimate of “as many as a dozen [bristlemouths] per square meter of ocean.”
15:00 – A recent discussion of the “burglar alarm hypothesis.”
18:00 – The website for the Johnsen Lab at Duke University.
24:00 – A chart and discussion of the depth zones of the ocean.
29:30 – A study by Séverine Martini and Steven Haddock quantifying the prevalence of bioluminescence at different depths. A popular write-up of the same study.
33:00 – A popular article on vertical migration in the ocean, also called “diel vertical migration.” A recent scientific study of the phenomenon.
39:00 – A recent article on the evolution of bioluminescence.
45:00 – For detailed scientific discussion of the physical basis of bioluminescence, fluorescence, and other phenomena we discuss, see Dr. Johnson’s book, The Optics of Life.
52:00 – For previous episodes on the use of sound in the animal kingdom, see here and here. For our previous episode on electroreception and electric ecology (including in marine organisms), see here.
57:00 – For more on the functions of bioluminescence, see here. For a report of a recently discovered function of bioluminescence, see here.
1:03:00 – An article by Dr. Johnsen about the different colors of bioluminescence present in the deep sea.
1:05:00 – A video of ostracod mating displays.
1:08:00 – For our recent episode on cave art, see here.
1:16:00 – For our earlier episode on firefly synchronization, see here.
Recommendations
Website and review article by Steven Haddock
The lab of Todd Oakley
Below the edge of darkness, Edie Widder
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.
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