Many Minds

Hello friends, and happy new year! We're gearing up for a new run of episodes starting later in January. In the meanwhile, enjoy this pick from our archives.
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[originally aired October 16, 2024]
IQ is, to say the least, a fraught concept. Psychologists have studied IQ—or g for "general cognitive ability"—maybe more than any other psychological construct. And they've learned some interesting things about it. That it's remarkably stable over the lifespan. That it really is general: people who ace one test of intellectual ability tend to ace others. And that IQs have risen markedly over the last century. At the same time, IQ seems to be met with increasing squeamishness, if not outright disdain, in many circles. It's often seen as crude, misguided, reductive—maybe a whole lot worse. There's no question, after all, that IQ has been misused—that it still gets misused—for all kinds of racist, classist, colonialist purposes. As if this wasn't all thorny enough, the study of IQ is also intimately bound up with the study of genetics. It's right there in the roiling center of debates about how genes and environment make us who we are. So, yeah, what to make of all this? How should we be thinking about IQ?
My guest today is Dr. Eric Turkheimer. Eric is Professor of Psychology at the University of Virginia. He has studied intelligence and many other complex human traits for decades, and he's a major figure in the field of "behavior genetics." Eric also has a new book out this fall—which I highly recommend—titled Understanding the Nature-Nurture Debate. In a field that has sometimes been accused of rampant optimism, Eric is—as you'll hear—a bit more measured.
In this conversation, Eric and I focus on intelligence and its putatively genetic basis. We talk about why Eric doubts that we are anywhere close to an account of the biology of IQ. We discuss what makes intelligence such a formidable construct in psychology and why essentialist understandings of it are so intuitive. We talk about Francis Galton and the long shadow he's cast on the study of human behavior. We discuss the classic era of Twin Studies—an era in which researchers started to derive quantitative estimates of the heritability of complex traits. We talk about how the main takeaway from that era was that genes are quite important indeed, and about how more recent genetic techniques suggest that takeaway may have been a bit simplistic. Along the way, Eric and I touch on spelling ability, child prodigies, the chemical composition of money, the shared quirks of twins reared apart, the Flynn Effect, the Reverse Flynn Effect, birth order, the genetics of height, the problem of missing heritability, whether we should still be using IQ scores, and the role of behavior genetics in the broader social sciences. 
Alright folks, lots in here—let's just get to it. On to my conversation with Dr. Eric Turkheimer. Enjoy!
 
A transcript of this episode is available here.
 
Notes and links
3:30 – The 1994 book The Bell Curve, by Richard Herrnstein a Charles Murray, dealt largely with the putative social implications of IQ research. It was extremely controversial and widely discussed. For an overview of the book and controversy, see the Wikipedia article here.
6:00 – For discussion of the "all parents are environmentalists…" quip, see here.
12:00 – The notion of "multiple intelligences" was popularized by the psychologist Howard Gardner—see here for an overview. See here for an attempt to test the claims of the "multiple intelligences" framework using some of the methods of traditional IQ research. For work on EQ (or Emotional Intelligence) see here.
19:00 – Dr. Turkheimer has also laid out his spelling test analogy in a Substack post.
22:30 – Dr. Turkheimer's 1998 paper, "Heritability and Biological Explanation."
24:30 – For an in-passing treatment of the processing efficiency idea, see p. 195 of Daniel Nettle's book Personality. See also Richard Haier's book, The Neuroscience of Intelligence.
26:00 – The original study on the relationship between pupil size and intelligence. A more recent study that fails to replicate those findings.
31:00 – For an argument that child prodigies constitute an argument for "nature," see here. For a memorable narrative account of one child prodigy, see here.
32:00 – A meta-analysis of the Flynn effect. We have previously discussed the Flynn Effect in an episode with Michael Muthukrishna.
37:00 – James Flynn's book, What is Intelligence? On the reversal of the Flynn Effect, see here.
40:00 – The phrase "nature-nurture" originally comes from Shakespeare and was picked up by Francis Galton. In The Tempest, Prospero describes Caliban as "a born devil on whose nature/ Nurture can never stick."
41:00 – For a biography of Galton, see here. For an article-length account of Galton's role in the birth of eugenics, see here.
50:00 – For an account of R.A. Fisher's 1918 paper and its continuing influence, see here.
55:00 – See Dr. Turkheimer's paper on the "nonshared environment"—E in the ACE model.
57:00 – A study coming out of the Minnesota Study of Twins reared apart. A New York Times article recounting some of the interesting anecdata in the Minnesota Study.
1:00:00 – See Dr. Turkheimer's 2000 paper on the "three laws of behavior genetics." Note that this is not, in fact, Dr. Turkheimer's most cited paper (though it is very well cited).
1:03:00 – For another view of the state of behavior genetics in the postgenomic era, see here.
1:11:00 – For Dr. Turkheimer's work on poverty, heritability, and IQ, see here.
1:13:00 – A recent large-scale analysis of birth order effects on personality.
1:16:00 – For Dr. Turkheimer's take on the missing heritability problem, see here and here.   
1:19:00 – A recent study on the missing heritability problem in the case of height.
1:30:00 – On the dark side of IQ, see Chapter 9 of Dr. Turkheimer's book. See also Radiolab's series on g.
1:31:00 – See Dr. Turkheimer's Substack, The Gloomy Prospect.
 
Recommendations
The Genetic Lottery, Kathryn Paige Harden
Intelligence, Stuart Ritchie
Intelligence and How to Get It, Richard Nisbett
"Why our IQ levels are higher than our grandparents'' (Ted talk), James Flynn
 
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).

Hello there, friends! We hope you're having a restful holiday, or a lively holiday, or whatever mix of those you prefer. As the year draws to a close, we at Many Minds are taking a much needed pause ourselves. But we wanted to share with you an episode from a podcast that we've been following for some time called On Humans. It's hosted by Ilari Mäkelä. It looks at humanity from all angles to understand where we come from and where we're going. The episode we're sharing features an interview with biologist and historian of science, Matthew Cobb; he's also the author of the book, The Idea of the Brain: The Past and Future of Neuroscience. In it, Ilari and Matthew take a zoomed-out view of the human brain and of our quest to understand it. This episode is actually part of a 5-part mini-series that On Humans did all about the human brain. So if you enjoy it, you may want to check out that broader series.
 
Alright friends, have a great close of 2025 and a great start to 2026. We'll see you in January with our first episode of the new year. In the meanwhile, enjoy this offering from our friends at On Humans.
 
 
The original show notes for this On Humans episode can be viewed here. You can follow the On Humans podcast through their newsletter or on Bluesky.

Alright, friends—we've come to the end of the 2025 run of Many Minds!
Our final episode of the year is an audio essay by yours truly. This is a classic format for the show, one that we only do every so often. Today's essay is about names. It's about the question of whether animals have something like names for each other. And it's also about a deeper question: What even is a name? How do humans use names? How does the historical and ethnographic record kind of complicate our everyday understanding of what names are. I had a lot of fun putting this together, and I do hope you enjoy it. 
Now, the holiday season is a time when people might be shopping around for new podcasts to listen to. That makes it a great time to recommend us to your friends and family and colleagues. You can think of it as an especially thoughtful gift, one that's absolutely free, and that keeps on giving throughout the year. 
Speaking of gifts, as an addendum to this episode you'll find a little stocking stuffer after the credits. It's a reading of a poem that figures prominently in today's essay. 
Without further ado, here is my essay—'In search of names.' Enjoy!
 
A text version of this essay will be published shortly.
 
Notes
2:00 – The text of 'The Naming of Cats' by T.S. Eliot is here. See also the full collection, Old Possum's Book of Practical Cats. The lines about cats' taste preferences and cats having different kinds of minds comes from another poem in the collection, 'The Ad-Dressing of Cats.'
3:00 – The 2019 study finding that cats know their names, and the 2022 study showing that cats know the names of their friends.
4:00 – For an overview of research on dolphin "signature whistles," see here.
5:00 – For the 2024 study reporting name-like rumbles in elephants, see here. 
6:00 – For the 2024 study reporting vocal labels for individuals in marmosets, see here. A critical response to the study is here; the authors' response to the criticism is here.
12:00 – For overviews of cross-cultural variation in names and naming practices, see here, here, here, and here. Richard Alford's 1988 study, published in book form, is here. 
13:30 – The study reporting name signs in Kata Kolok is here.
15:00 – For research on expectations based on the sounds of people's names, see here and here.
16:00 – For recent work on the "face-name matching effect," see here. For the study on "nominative determinism" in the medical profession, see here. (Note that, while this latter study does report empirical data, its rigor is questionable. And, yet, at least one other study has reported similar findings.)
17:30 – For the example of over-used names in Scotland, see here. 
19:30 – For discussion of names in New Guinea, see here. For examples of research on "teknonymy," see  here and here. For discussion of Penan "necronyms," see here. 
20:30 – For an overview of name taboos, see here. For more on "alexinomia," see here.
22:30 – For an example of recent work on "name uniqueness," see here.  
23:00 – William Safire's column on dog names is here. The study of gravestones in the world's oldest pet cemetery is here.  
 
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.
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 Bluesky (@manymindspod.bsky.social).

Not long ago culture was considered rare in nature, maybe even uniquely human. But that's changed. We now know that the tree of life is buzzing with culture—and not just on a few lonely branches. Creatures great and small learn songs, migration routes, and feeding techniques from each other. Many species build up reservoirs of knowledge over generations. This has profound implications, not just for our understanding of the natural world, but also for our efforts to protect it. 
My guest today is Dr. Philippa Brakes. Philippa is an Honorary Lecturer at the University of Exeter, with one foot in science and another in conservation. She's both a behavioral ecologist, focusing on whales and dolphins, and a leading voice—for more than a decade now—urging conservationists to take animal cultures seriously. 
Here, Philippa and I talk about how researchers define culture and social learning in animals. We tour the mounting evidence for culture across species—in birds, in apes, in fish, possibly even in insects. We discuss the methods that scientists use to infer that behaviors are socially learned. We consider how animal culture complicates the conservation enterprise. We also discuss the idea that animal cultures have intrinsic value—not value for us humans, not value that can be easily quantified, but value for the animals themselves. Along the way Philippa and I talk about the notion of "cultural rescue"; indigenous understandings of animal culture; cases where social learning is maladaptive; human-animal mutualism; fashion trends; the idea of conserving "cultural capacity"; elephant matriarchs and other "keystone individuals"; golden lion tamarins, herring, and regent honey-eaters; and the question of why some orcas wear salmon as hats.
Alright friends, this topic has been on our wish list for a while now. Hope you enjoy it!
 
Notes 
2:30 – For academic articles by Dr. Brakes and colleagues on the importance of animal culture for conservation, see here, here, and here. The last of these is the introduction to a recent special issue on the topic. Many of the topics discussed in this episode are also covered in this issue. 
3:30 – The case of the golden lion tamarins is discussed here.
5:00 – For more about the Convention on the Conservation of Migratory Species (or CMS) of Wild Animals, see here. 
9:00 – For a classic paper on social learning in animals, see here. For a relatively recent, detailed overview of animal culture, see here. For a short primer on animal culture, see here.
10:00 – For discussion of the riskiness of long-line depredation, see here.
12:00 – For a study by Dr. Sonja Wild and colleagues on bottlenose dolphin declines following a heat wave—and how these declines may have been buffered by tool-using traditions—see here. 
15:00 – For the review of cetacean foraging tactics by Dr. Taylor Hersh and colleagues, see here. 
17:00 – For a primer on honeyguides (and their mutualism with honey hunters), see here.
20:00 – For a recent review of culture and social learning in birds, see here. For a review of conservation of avian song culture, see here.
25:00 – For a review of (the conservation of) chimpanzee culture, see here.
28:00 – For the initial report of chimpanzees putting grass in their ears, see here. For more on the phenomenon of orcas wearing salmon hats, see here.
33:00 – For a recent review of culture and social learning in fish, see here. 
35:00 – For the recent study on "collective memory loss" in herring, see here.
39:00 ­– For more on the possibility of social learning in insects, see here. For a video of the puzzle box experiment in bees, see here.
44:00 – For a recent review of the "methodological toolkit" used by researchers in the study of social learning in animals, see here.
47:00 – For the study using network-based diffusion analysis to understand the spread of feeding strategies in humpback whales, see here.
49:00 – For the original 2000 study on the spread of humpback whale song, see here. For a more recent study of "revolutions" in whale song, see here. 
53:00 – For an example of work looking at changes in whale song as a result of human noise, see here. 
55:00 – For more on the idea of "keystone individuals" in the case of elephants, see here. For more on menopause and the so-called grandmother hypothesis, see our earlier episode with Alison Gopnik. 
1:05:00 – A recent editorial calling for the protection of animal cultural heritage under UNESCO.
 
Recommendations
The Cultural Lives of Whales and Dolphins, by Hal Whitehead and Luke Rendell
Animal Social Complexity, edited by Frans de Waal and Peter Tyack
The Evolution of Cetacean Societies, by Darren P. Croft et al.
The Edge of Sentience, by Jonathan Birch (featured on an earlier episode)
 
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.
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 Bluesky (@manymindspod.bsky.social).

Everyone loves a good evolutionary puzzle. Why do we have appendices? Why do we dream? Why do we blush? At first glance, memory would not seem to be in this category. It's clearly useful to remember stuff, after all—to know where to find food, to remember your mistakes so you don't repeat them, to recall who's friendly and who's fierce. In fact, though, certain aspects of memory—when you hold them up to the light—turn out to be quite puzzling indeed.
My guests today are Dr. Ali Boyle and Dr. Johannes Mahr. Ali is a philosopher at the London School of Economics (LSE); Johannes is a philosopher at York University, in Toronto. Both have written extensively about the functions of memory, and, in particular, about the functions of episodic memory—that capacity for calling up specific events and experiences from our own lives. 
Here, Ali, Johannes and I lay out the textbook taxonomy of memory, and discuss how episodic memory has drawn the lion's share of philosophical interest. We pick apart the relationship between episodic memory and another major type of long-term memory, semantic memory. We sketch a range of different accounts of the evolved functions of episodic memory, including Johannes's proposal that episodic memory serves communication and Ali's proposal that it fuels semantic memory. And, finally, we consider what this all means for our understanding of memory in children and in animals. Along the way, we touch on Highly Superior Autobiographical Memory, infantile amnesia, evidential systems in language, imagination, "simulationist" theories of episodic memory, what it feels like to remember, collective memory, the hippocampus, cryptomnesia, and the cow's digestive system as a metaphor for memory. 
If you're enjoying Many Minds, you might consider leaving us a rating or review on your platform of choice, or maybe giving us a shout-out on social media. Thanks so much in advance for supporting us, friends!
 
Notes
4:30 – For a broad orientation to memory research in the cognitive sciences, see here. For a broad orientation to the philosophy of memory, see here. 
13:00 – See here for Dr. Boyle's paper on the "impure phenomenology" of episodic memory.
16:30 – For more on the idea of "WEIRD"-ness and the "WEIRD problem" in psychology, see our previous audio essay and our recent episode on childhood across cultures.
20:00 – For more on metaphors for memory in the cognitive sciences, see here (in which an apparently different "cow stomach" metaphor for memory is discussed). Note that cows do not, in fact, have four stomachs, but rather a single stomach with four distinct chambers.
24:00 – For an overview of the cognitive neuroscience of episodic memory, see here.
31:30 – For a discussion of the commonsense "mnemonic view" of episodic memory, see Dr. Boyle's recent article. 
37:00 – For one influential articulation of a "simulationist" account of episodic memory, see here. 
40:00 – For the proposal by Dr. Mahr and his colleague that episodic memory is for communication, see here and here.
45:00 – For more on evidential systems in language, see here and here. 
48:00 – For the study by Dr. Mahr and colleagues on source memory in children, see here.
51:30 ­– For Dr. Boyle's proposal that episodic memory is for semantic memory, see here. For another of Dr. Boyle's discussions of the functions of episodic memory, see here.
1:02:00 – For more of Dr. Mahr's ideas about the cultural evolution of the "epistemic tag" that distinguishes episodic memory, see here.
1:03:00 – Partially digested stomach contents are sometimes known as "chyme."
1:07:00 – A news story about recent findings on infantile amnesia. 
1:08:00 – A recent review article about Highly Superior Autobiographical Memory.
1:12:00 – An empirical study on the phenomenology of "cryptomnesia."
1:15:00 – For a recent discussion of episodic memory in animals, see this paper by Dr. Boyle and a colleague. Examples of Dr. Boyle's other work on memory in animals are here and here.
 
Recommendations
The Memory Palace (blog)
The Invention of Tomorrow, by Thomas Suddendorf, Jonathan Redshaw, & Adam Bulley (see also our episode featuring this book)
Searching for Memory, by Daniel Schacter
The Enigma of Reason, by Hugo Mercier & Dan Sperber
 
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.
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 Bluesky (@manymindspod.bsky.social).