Island of the tool users
Many Minds
Tool use is rare in the animal kingdom—but maybe not as rare as we once thought. Since Jane Goodall famously observed a chimpanzee fishing for termites, many new examples of animals using tools have come to light. Birds using sticks to forage for grubs. Sea otters using rocks to smash open mussels. Digger wasps using stones to close off their burrows. But as these examples mount, so do the scientific questions. What is tool use, really? What different forms does it take? Does it always imply a high degree of intelligence? And perhaps the biggest question of all: Why do some creatures use...
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Cognitive offloading and its consequences
Many Minds
For thousands of years—maybe for as long as we've been human—we've offloaded our thinking. We've counted on our fingers. We've carved tallies into bone. We've invented a long series of tools to help us reason, remember, and manage information—tools like abacuses, calendars, writing systems, calculators, smartphones, and many, many more. So cognitive offloading is hardly new—but the questions around it seem newly urgent. As cognitive technologies accumulate, as opportunities for offloading tempt us at every turn, as headlines warn of "digital dementia" and "cognitive surrender," it...
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Coming of age in Ngogo
Many Minds
It's a familiar story in many ways. A child is born, and for years afterward is adored and indulged and anchored to home and family. But then the child grows up and starts crossing that long threshold into adulthood. The transition proves—to say the least—a bit turbulent. Now when I say this story is familiar, I don't just mean familiar to us as human beings. After all, a similar story has long played out among our closest cousins, the chimpanzees. My guest today is . Rachna co-directs the longstanding in Uganda and is an incoming Assistant Professor of Psychology at the University of...
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The natural history of linguistic diversity
Many Minds
Thousands of languages are used around the world today, and this linguistic diversity is a precious part of our human heritage. But it's also more than that. Linguistic diversity provides clues—a vast crazy quilt of clues—about how language works, about how history has unfolded, about the dynamics of culture, and about the nature of the human mind. My guest today is . Damián is an based at the at the Pompeu Fabra University in Barcelona. Over the last decade or so, Damián’s emerged as one of the most innovative researchers in the study of language and linguistic diversity. He’s...
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From the archive: Electric ecology
Many Minds
Hi friends! We're still taking a bit of a summer pause. We'll be back at the end of August—in the meanwhile, enjoy this listener favorite from our archives! ----- [originally aired September 19, 2024] There's a bit of a buzz out there, right now, but maybe you haven’t noticed. It's in the water, it's in the air. It's electricity—and it's all around us, all the time, including in some places you might not have expected to find it. We humans, after all, are not super tuned in to this layer of reality. But many other creatures are—and scientists are starting to take note. My guest today...
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From the archive: Varieties of childhood
Many Minds
Hi friends! We're taking a bit of a summer pause. We'll be back soon—in the meanwhile, enjoy this listener favorite from our archives! ----- [originally aired July 10, 2025] 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...
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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...
info_outlineNewton 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 Dr. Matt Longo. Matt is Professor of Cognitive Neuroscience at Birkbeck, University of London. He's the author of the recent book, The Invisible Hand, a wide-ranging tour of the human hand and how it's geared into the brain.
Here, Matt and I talk about the difference between the "visible hand"—that is, its physical structure—and the "invisible hand"—its representation in the brain. We consider the evolution of the visible hand and whether there really is anything truly distinctive or impressive about it. We talk about the biology of touch. We tour the invisible hand, discussing how—through cortical magnification—the hand becomes over-represented in the brain's sensory maps. We catalogue a few ways that the hands can go awry. And we talk about whether we should feel any nostalgia for all the hand-based activities and crafts that we're losing. Along the way, we also touch on star-nosed moles and raccoons; tetrapods and the primitive archetype; hand dominance; the parallel between a horse's knee and a human's wrist; tool use, plasticity and abstraction; homunculi; the rubber-hand illusion; supernumerary fingers; the Third Thumb project; and the question of what it might unlock if dolphins had hands.
Alright, friends, this is a fun one. On to my interview with Dr. Matt Longo!
Notes
3:00 – For discussion of the many traits and behaviors that have been proposed as uniquely human, see our earlier audio essay.
5:00 – For an example of the “if only dolphins had hands” thought experiment, see here.
8:00 – See The Principles of Anatomy as Seen in the Hand by Frederic Wood Jones.
10:30 – Dr. Longo’s book, The Invisible Hand, is available open access here.
16:00 – For discussion of how—in horses and other species—the five digits have been reduced or otherwise tweaked over evolution, see here. For an image showing examples of homology between the human forelimb and the forelimbs of other creatures, see here.
19:00 – For a brief discussion of “thumb opposability,” see here. For an influential discussion of hand morphology and human hand grips, see work by Mary Marzke here.
30:00 – For our earlier episode on the brain’s many maps, see here.
34:00 – For a discussion of Penfield’s work and the idea of a “homunculus” in the brain, see here.
42:00 – For an illustration of a “homunculus” with big lips and hands, see here.
44:30 – For more on the star-nosed mole and its distinctive appendage, see here.
49:00 – For the report that first coined the term “numbsense,” see here. For recent work on “anarchic hand,” see here. For more on phantom limbs, see here. For a classic study of the “rubber hand illusion,” see here.
59:30 – For a discussion of hand-dominance across primate species, see here.
1:03:00 – More on the “Third Thumb” project.
1:06:00 – A classic case of “motor equivalence” is seen in handwriting.
Recommendations
Marco Catani, ‘A little man of some importance’
Tracy Kivell, ‘Evidence in hand: Recent discoveries and the early evolution of human manual manipulation’
Hands, by John Napier
Tile art credit: Image by Picsea via Unsplash
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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