127 | Erich Jarvis on Language, Birds, and People

Many characteristics go into making human beings special — brain size, opposable thumbs, etc. Surely one of the most important is language, and in particular the ability to learn new sounds and use them for communication. Many other species communicate through sound, but only a very few — humans, elephants, bats, cetaceans, and a handful of bird species — learn new sounds in order to do so. Erich Jarvis has been shedding enormous light on the process of vocal learning, by studying birds and comparing them to humans. He argues that there is a particular mental circuit in the brains of parrots (for example) responsible for vocal learning, and that it corresponds to similar circuits in the human brain. This has implications for the development of intelligence and other important human characteristics.

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Erich Jarvis received his Ph.D. in Animal Behavior and Molecular Neurobehavior from Rockefeller University. He is currently a professor in the Laboratory of Neurogenetics of Language at Rockefeller and an investigator at the Howard Hughes Medical Institute. Among his many awards are the Alan T. Waterman Award from the National Science Foundation, an American Philosophical Society Award, a Packard Foundation fellowship, an NIH Director’s Pioneer award, Northwestern University’s Distinguished Role Model in Science award, and the Summit Award from the American Society for Association Executives.

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0:00:01 Sean Carroll: Hello, everyone. Welcome to the Mindscape Podcast. I’m your host, Sean Carroll, and I don’t need to point out the obvious here, but I am talking to you right now. You are listening. We are engaging in a communication act mediated by speech, by vocalizations. This is something that human beings can do. We can talk to each other. We have the power of language. Where did that come from? Is it common in the animal kingdom? Is it common in other species? Well, yes and no, and this is what we’re going to get into in today’s podcast.

0:00:33 SC: Erich Jarvis is a leading scientist, he’s at Rockefeller University, who studies the origins of language and vocal learning and how they arise not only in human beings, but in other species, especially in birds. Birds are… Have a… Several of the other species where vocal learning, the ability to learn new sounds, is a common trait. And you might think that, well, I talk to my dog and my cat. You can give instructions to horses or elephants or whatever, but that’s not quite language. And the interesting distinction is that dogs and cats can bark and meow, but they can’t learn new sounds. Those sounds that they have to communicate with, they’re born with, more or less. Maybe they learn to meow, but they always had the ability to do it.

0:01:20 SC: And so it’s a very small number of species that actually has the ability to learn new sounds and then put them to use in communicating with each other. As we’ll go through, I’m not going to give away all of the fun things that happen in the podcast, but in addition to a few mammal species, there’s several species of birds. You know about parrots, parakeets, hummingbirds also, and so forth have this ability to learn new sounds. So one question is, why is this ability so rare? It seems kind of useful. And then, why do we human beings in particular put it to use in the way that we do? Parakeets don’t make grammatically complicated sentences in the same way that human beings do.

0:02:01 SC: And Erich is a wonderful person to talk to because he kind of studies this problem on all different levels. He will record birdsong and sort of analyze it, has plenty of birds in his lab. He will also do genetic analysis, comparing the genes between different species, and then he will also do sort of brain level analysis looking into the brains of the birds and other species to see what’s going on. And the hypothesis is that there’s literally a motor circuit in the brain that was sort of borrowed from other motor circuits, maybe what we used to move our hands or our faces or something like that, that was repurposed to really just focus in on making new sounds, and he claims that by looking both at the genes and at the structure of brains, you can see similarities in the brains of parakeets and human beings that you don’t see if you compare parakeets to falcons, or human beings to chimpanzees.

0:02:57 SC: We share this ability, which is kind of rare and interesting, and it’s fun. If you have time, I recommend sticking around to the end of this podcast, because we start hypothesizing on some fun things and some new ideas, and that’s what makes science and podcasting and their intersection pretty great, because we can let our hair down a little bit. We can talk about ideas that bring in lots of different points of view, and maybe something new and interesting happens there. Certainly, talking about things is an important part of what we do. So knowing how that happens, knowing why we do it, knowing how to make it better, maybe even give that ability to new species is something we should know more about. So let’s go.

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0:03:54 SC: Erich Jarvis, welcome to the Mindscape Podcast.

0:03:56 Erich Jarvis: Thank you.

0:03:57 SC: We’re interested in spoken language in humans and other species and so forth, so here’s my question. Every morning, 5:00 AM, I’m asleep in bed and my cat, Ariel, climbs on top of me and starts meowing, and this is clearly a vocalization that is meant to communicate something, namely, she is hungry, and it is breakfast time. But I think that by the standards of what you’re interested in, this does not count as spoken language or vocal learning. So what is the difference between just communicating by making sounds and what you’re interested in?

0:04:34 EJ: Yeah, so that meow coming from the cat, that’s a natural ability that it’s born with like our eye color, height, and so forth where there’s… It’s mostly genetically pre-determined. The cat can learn how to use a meow in different contexts, like for food and water, and we call that vocal usage learning, but not vocal production learning, which is the ability to produce novel sounds that you’re not born to be able to produce.

0:05:04 SC: Okay. So it’s not just a matter of the meaningfulness of the sound, so other… Plenty of species have meaningful communication via sounds, but you’re interested in learning new sounds.

0:05:16 EJ: That’s correct. So learning new sounds that you copy from other people or you can even modify, I mean, imitate sounds that you hear in your environment, so it’s the ability to actually modulate the acoustic structure and the sequence of the sounds that you produce.

0:05:37 SC: Okay, and that’s one component of what we call spoken language. Maybe it’ll be useful just to put things in context to talk about what the other components of spoken language are. Like many things that we’re very familiar with, it’s a simple thing that actually has a lot of different moving parts.

0:05:52 EJ: That’s right. Yeah, we humans don’t realize that spoken language has multiple components to it, of course, that I just mentioned one of them, vocal production learning. Another is auditory learning, and this component is actually pretty common. Like pet animals, like a dog can learn how to understand what the meaning of the word sit means and actually sit, or in other language like sientese in Spanish, or get the ball, the newspaper, get this toy, and so forth. So this is necessary for spoken language because we need to form an auditory memory of what we’re going to imitate in our speech, but it’s not sufficient.

0:06:31 SC: Right. And so… So I can even… So you’re saying the we have auditory learning and vocal production learning so… Sorry. Vocal usage learning is the thing that the cat has?

0:06:42 EJ: No. Vocal usage learning is common, where you learn how to use a sound in different contexts, even innate sounds. But it’s vocal production learning, or just more simply vocal learning itself, that’s very rare. And auditory learning that I had just mentioned as a second component is actually common.

0:07:01 SC: Are there… It sounds like, to me, auditory learning, the ability to hear and understand, and vocal usage learning, the ability to make a noise and be understood, those would be pretty closely correlated. Are there species that have one but not the other?

0:07:16 EJ: Yeah, yeah. So, like I mentioned that dogs have the ability of vocal… Of auditory learning, I’m sorry, but without the vocal production learning.

0:07:26 SC: But they have vocal usage learning, you said, right?

0:07:29 EJ: Say it again?

0:07:30 SC: Sorry, I’m trying to figure out whether or not a species can have auditory learning, but not vocal usage learning.

0:07:37 EJ: Ah, yes. Okay. That’s not really been tested, but I doubt that they have those two separate. I bet you, for most species, it’s going to be they have both, except for some lizards that don’t vocalize at all.

0:07:56 SC: So they can hear and understand sounds but they don’t make them?

0:08:00 EJ: That’s correct.

0:08:00 SC: Interesting.

0:08:01 EJ: They don’t make them, at least through their vocal tract.

0:08:04 SC: Okay, and interesting. Yeah. Alright. So… And I think that one of the slippery things is that because things like cats and dogs or horses or whatever, have this auditory learning and vocal usage learning, we think of that as just a primitive form of speech, right, and then it’s just sort of a continuum all the way up to what we have but… And probably, I’m guessing that in most people’s minds, the real difference is the idea of symbolic language, right, the idea that we make a sound and the sound doesn’t have any intrinsic meaning, but we associate it with something. Is that something that dogs and cats can have?

0:08:43 EJ: Yes. So that’s the surprising thing, is that… That these species that don’t have spoken language or don’t have vocal learning can still have symbolic understanding to a certain degree. So getting back to dogs, you can teach them to understand the meaning of different objects, and even whole human sentences, but… Or even in a vervet monkey, you can get them to… Not you just get them, they do this naturally out in the wild where they all associate even some of their innate sounds, whether an eagle in the sky or a snake on the ground, different innate sounds will mean different things that they culturally pass on from one generation to the next. But the ability to modify those sounds is innate.

0:09:36 SC: Interesting. And so what is the evidence that they culturally pass it on? That’s fascinating.

0:09:40 EJ: Yeah. There’s work of Seyfarth and Cheney where… I won’t say it’s solid evidence but it’s circumstantial, but it’s indicative of it, where young animals will respond to all different kinds of alarm calls that the adults make. And through experience with the adults, they learn that they should, let’s say, run up in the tree with this particular alarm call or stay on the ground with this other one, or go to some other tree with food with this particular call. They’re not born with that understanding, they have to learn it through experience with their own kind.

0:10:17 SC: Interesting. And is the famous case of Koko the gorilla an example of this, where she learned sign language? Yeah.

0:10:23 EJ: Absolutely, yes. Yeah, Koko… Depending on what literature you read, it was anywhere from 2000 to 7000 words that Koko understood. Okay, I think it was 7000 kind of understood, about 1000 to 2000 that she could sign, with hands, but not with the voice. So that’s a lot for a non-human animal.

[chuckle]

0:10:43 EJ: Even though our vocabulary is 20,000 words, it’s still… 2000 to 7000 is a lot.

0:10:49 SC: It is a lot. But I’ve heard, yeah, that there are Koko truthers who think that her abilities were exaggerated a little bit.

0:10:56 EJ: Yeah, I don’t know, it could be. I don’t want to say yes or no to that. I will say that just putting it in relative perspective, Koko can’t even utter a single word.

0:11:08 SC: Right, right.

0:11:09 EJ: So whether it’s 1000 or 2000 or 7000 words from understanding, not even a single word from production is a huge difference.

0:11:19 SC: And is Koko or are other non-human animals… Before we get to the vocal stuff, which is obviously what we’re going to focus on, but what about grammar? Is that something that other animals know about?

0:11:31 EJ: Yeah. I don’t… I would say no. There’s not enough evidence to indicate that Koko had a grammar, but it’s hard to… Even in the linguistic community, it’s hard to, I think, really define what you would call grammar and syntax in a non-human animal.

0:11:52 SC: Right.

0:11:53 EJ: Just to say, I’m going to use a more simple word, I consider more simple, is syntax, where there is a non-random ordering of sounds. Vocal learners do that. There are some rules that are there, and a grammar where there is a higher order rule-based organizing of those sounds. I don’t think there’s good evidence for that yet, because one reason is that I don’t think it’s been thoroughly tested yet.

0:12:21 SC: Okay, good. Yeah, one of the goals of the podcast is to inspire young people who are not yet graduate students doing work to pick some good problems. So that sounds like one that is worth tackling.

0:12:32 EJ: I would agree.

0:12:34 SC: And then we get to the vocal learning part, which is what we care mostly about here. It’s interesting to me the connection that I get from reading your stuff between the physical ability to learn to make different sounds and the communication ability that we have. So what is this vocal learning thing and why do we care about it so much?

0:12:55 EJ: Yeah. So it’s the ability to hear the sounds… It’s ability not only from the auditory memories of the sounds that you hear, but then to actually repeat them. And to not only repeat simple sounds like individual phonemes like ba, da, ga, but to actually produce whole a sequence of sounds and words and so forth. And you ask about recombining them in species from the auditory domain, from the hearing domain. But you do get that in some parrots where they can take learned human speech sounds and recombine them into new words or new meanings that wasn’t taught to them. So…

0:13:33 SC: Oh, that’s interesting.

0:13:34 EJ: So… So, yes. So this ability, and it varies from one species to another, being simple in some and more complex in the others.

0:13:44 SC: So many species can make sounds of different forms, it seems almost surprising that the ability to learn how to make new sounds is so rare.

0:13:53 EJ: Yeah, yeah, so… Exactly, and it’s so rare and that rareness does come along with differences in the biology, getting back to your original question, which is, we find that the species that can produce learned sounds have a specialized forebrain circuit that you don’t find in the species that can’t. Alright, and that circuit actually has a lot of similarities with brain pathways that control learning how to move.

0:14:20 SC: Right. So therefore maybe it was hard to evolve it?

0:14:25 EJ: Yeah. Yeah, I think it’s… Yeah, and it’s not just one brain region, it’s a whole circuit.

0:14:30 SC: Right, okay.

0:14:31 EJ: So I think it’s… It’s interesting how to think about this, whether it’s hard to evolve, or it’s hard to keep it if you evolve it.

0:14:39 SC: Okay. I guess maybe for the benefit of the audience out there, how many species we talking about here? Who counts? People count but who else?

0:14:48 EJ: Yeah. So we’re talking 5 out of the 30 or so different orders of mammals, I think it’s close to 50 really orders of mammals, and that’s us humans… Actually, amongst us humans, it’s only amongst the primates, that is, it’s only humans. Then you have the cetaceans, those are the whales and dolphins, and there are multiple vocal learners built in that group. You have the bats who produce in the ultrasonic range that we can’t hear, and you have the pinnipeds, who are the sea lions and seals.

0:15:20 SC: Oh, okay.

0:15:23 EJ: So it’s just those groups, and they don’t have close relatives. Oh, I forgot one more, which is the… The elephants.

0:15:29 SC: Alright.

0:15:30 EJ: And amongst birds… Amongst birds, there are three of them, parrots, songbirds and hummingbird. And the rest of the 40-something bird lineages don’t have vocal learners.

0:15:37 SC: And that’s just a… Never a list anyone would guess on the basis of anything else.

0:15:43 EJ: No.

0:15:43 SC: They’re not sort of like, we’re much closer to chimpanzees or monkeys, but it’s bats and parrots that share this ability with us.

0:15:52 EJ: That’s right. It almost seems random, but I think there is an association with predations. I think the vocal learners are, for at least amongst mammals, are near the top of the food chain. And I think if you evolve this trait, you’re producing varied sounds that predators have a hard time habituating to and you’re more likely to be eaten.

0:16:20 SC: I’ll believe that for elephants and whales, you’ll have to convince me that for bats and parakeets, that they’re at the top of the food chain. [chuckle]

0:16:28 EJ: Right. So bats, they’re in the ultrasonic range where a lot of other species can’t hear them, and for songbirds and parrots, I didn’t have a good rationale there either until we, back in 2014, we created a phylogenetic tree of birds using whole genomes and discovered that they descended from apex predator birds back in the time of dinosaurs, who were called giant parrot birds by the palaeontologists.

0:16:56 SC: So, okay. So are little parrots… Parrots and parakeets, are they both… And hummingbirds, you said?

0:17:01 EJ: Hummingbirds, I don’t see that they have an ancestry with being apex predators and… Yeah, they’re just smallest animals, they’re pretty fast, though, at evading predators, so I think we can give them that. They’re some of the fastest flying birds besides falcons.

0:17:19 SC: So the birds that you mentioned are the only non-mammals that have this ability?

0:17:23 EJ: Yes, it’s only a group of mammals and a group of birds. So there are 70,000 vertebrate species, and many of them are fish, frogs, amphibians, reptiles, and of course, these bird and mammal groups, and of those 70,000 species, you can put them in roughly 260 orders. And so of those 260 orders, 8 of them are the vocal learners.

0:17:51 SC: Interesting. And do the… The birds just seem like an outlier, we can see that even though mammals seem very different from each other, they’re at least all mammals. Do these birds have other abilities we would qualify as linguistic?

0:18:04 EJ: Yeah. I would say the closest you get to that is in the parrots, where they will learn actually human speech words and do new recombinations of them.

0:18:16 SC: I see. So they make new words. Do they make sentences?

0:18:20 EJ: Yeah, they make sentences. Yes.

0:18:22 SC: Okay, and to convey meaning because they want something to happen.

0:18:26 EJ: Yeah. So I once talked to an owner of a famous parrot, parakeet is basically a small parrot, that’s what it means, who learned about 400 human words besides his own wobble song, and he would basically produce those words in new combinations and about 75, 70% of the time, they seem random, just random combinations of words, and 30% of the time, to the listening humans, they made sense. A new combination of words in a new situation that made sense.

0:19:04 SC: Are we… Are we worried that that’s the humans’ ability to see patterns where they don’t exist?

0:19:09 EJ: No, because Irene Pepperberg, who’s done some work on African gray parrots, doing experimental analysis of this, demonstrates that this happens in a non-random manner. It’s statistically significant that her parrots were producing words and combination words in appropriate social context.

0:19:30 SC: We tend to… Look, we’re human beings, we tend to think that we’re awesome and we’re at the top of everything, and the ability to do language and speech is one of our most important traits. Is there some kind of intelligence that parakeets and parrots and hummingbirds have that we’re not giving them credit for, or is there just a looser connection between vocal learning and intelligence that we might have guessed?

0:19:57 EJ: Overall, I think we humans overrate ourselves and thereby underrate other animals, including the non-vocal learner, but among the vocal learners there is some anecdotal evidence that the more learned kind of communication we do in humans and parrots and songbirds, including crows, who are a songbird, that there is a greater intelligence, but I’m going to say more of a social intelligence than anything, than other kinds of intelligence, and I think this is brought on because of the greater capacity for learned communication.

0:20:33 SC: So I’ve certainly seen these demonstrations of crows solving puzzles that are quite impressive, right?

0:20:40 EJ: Yes.

0:20:41 SC: But are crows… They’re not vocal learners. Were they in the group?

0:20:44 EJ: They actually are vocal learners. They don’t actually have a… Let’s say they don’t have a really loud advertising song like a canary would have, but they do produce low volume song in the bushes to each other, and their crows, the crowing vocalizations that they produce that you can hear and that’s pretty loud, is also learned. And there have been cases where crows have picked up human speech sounds.

0:21:13 SC: Alright, good, yeah, and the crows are definitely clever. There’s definitely some intelligence there.

0:21:17 EJ: Yeah.

0:21:17 SC: But maybe, even though we said it, it’s worth emphasizing that other primates don’t have this ability, and they are quite intelligent, so therefore there’s clearly something physiological that is a little bit different between a human being and chimpanzee or a gorilla.

0:21:33 EJ: Yes, there is. There’s something different physiological in the brain, and of course parts of the body as well, but it’s mostly when it comes to what we would call intelligent behavior and speech, it’s in the brain. And it’s this specialized circuit that I told you about, but there’s some other differences as well. One is that in humans, we have an extra copy of a gene called SRGAP2, and this extra copy causes the neurons to stay in a more immature state throughout our lives, and that more immature state is argued to allow us to learn more readily throughout our lives.

0:22:14 EJ: I think I’ll add we often forget more equally as well because of that than other species. Conversely, in parrots and songbirds, the vocal learning birds, they don’t have an extra copy of this gene, but they do have a greater, twice the density of neurons packed in the same amount of space as a non-vocal learning species, and I think that this doubling of neurons in the brain, without increasing brain size mathematically, allows them to have more extra brain circuits for vocal learning and other behaviors.

0:22:52 SC: I see. So is it more neurons overall or just in the sort of vocalization area?

0:22:58 EJ: It’s more neurons overall, which then, I and some others will argue, allows the capacity to have more neurons dedicated to vocal behavior.

0:23:10 SC: Okay. And is it just the brain, or is the difference between us and chimpanzees or whatever also in our mouths and lungs and larynxes?

0:23:18 EJ: Yeah, so there’s been an argument out there for many decades now, started by Lieberman, who argued that the descent of the larynx allows humans to produce a lot greater variety of sounds than other primates or animals overall, and the work of Tecumseh Fitch has shown that this is not true, that other animals, when they raise their heads up, can get their larynx descended as low as humans, and there are some animals that independently evolve a descended larynx, in some lions, but yet they don’t imitate sounds and produce speech like we do. So I think the evidence for that is pretty weak, or not there at all, actually evidence against a difference in the vocal organ that makes the ability for speech.

0:24:06 SC: Okay. But is this one of these things where we see in evolution where multiple things had to happen? So it sounds like you need that ability to vocalize, and then you also need the brain circuits to put it to work in learning things.

0:24:17 EJ: Yeah, I think multiple things did happen, including maybe some modifications to peripheral organs, but I don’t think it’s the descended larynx. For example, in the Fitch lab, they showed that if you take a post-mortem larynx of a macaque, a monkey basically, and blow air through it in different patterns and so forth, you can get that larynx to produce all kinds of sounds and phonemes like a human larynx would, and it doesn’t matter how far away you blow the air through that larynx in terms of its descent.

0:24:57 SC: So I guess you could imagine why evolution would like the animal to have the ability to make all sorts of different sounds, whether or not it was for speech in particular, or language or something like that.

0:25:09 EJ: Right. Yeah, I think it’s like, for example, there are two reasons why we think parrots can produce more complex learning sounds than other vocal learning birds like songbirds and hummingbirds. One is because they use the tongue more than the other species, like we use our tongues, not just our larynx to modulate the sound. Second is they, parrots and humans, have an extra brain pathway. It’s like a song system within a song system that controls this behavior.

0:25:43 SC: So an extra brain pathway is literally extra neurons, or a different wiring diagram for the existing neurons?

0:25:50 EJ: It’s both. It’s extra neurons, plus some differences in the wiring of those extra neurons compared to the original vocal learning pathway that we think they began with.

0:26:00 SC: And this relates to the motor circuit that you talked about earlier?

0:26:05 EJ: Yeah. What we think is that initially a motor learning pathway duplicated and gave rise to a vocal learning pathway, and then in humans and parrots, that new vocal learning pathway duplicated again and gave rise to a second one.

0:26:22 SC: Wow, okay. And by duplicating… You’ll forgive me, I’m just an innocent physicist here. That sounds hard to do, just like a duplicate motor pathway in your brain. Is that the kind of thing that arises all the time, or was that a really weird thing?

0:26:39 EJ: Yeah, I think it is hard to conceptualize how that happens. And one way I think about it is like a gene duplication. In the genome, one gene gets copied into another while the cell is undergoing cell division. So there’s an accidental copy, and that accidental copy then gets incorporated as a new copy of that genome. So I’m proposing here a new theory that maybe brain circuits actually can duplicate also during development, and maybe duplicating these circuits is a natural process, so that one motor circuit controls the hand, the other controls the feet, the chest and so forth, and now duplicated again, it controlled the larynx in the [0:27:20] ____.

0:27:20 SC: So I guess, now that I’m thinking about it, and you’re talking about it, the idea that you have in your genome a blueprint for making a certain kind of motor circuit, and then you just have some transcription error or whatever that duplicates it, is easier to imagine maybe than starting from scratch and building a new one.

0:27:40 EJ: Exactly. That’s how I’m thinking about it. That’s how I think it even… That’s the hypothesis I have about how it evolved.

0:27:46 SC: Right. And is there some specific motor circuit that did exist, that is the one that got duplicated, to help us control vocal learning or we don’t know?

0:28:00 EJ: I have two alternative views on that. One is that I think it is specific. It’s either the circuit that controls the oral-facial musculature, or the circuit that controls the hands.

0:28:11 SC: Ah, okay, that’d be very different, yeah.

0:28:14 EJ: Yeah, and the reason why I say the oral-facial musculature, because one of these circuits in the human brain is kind of next to or intermingled with the oral-facial musculature circuit that you can find in other species. The other isn’t. The other one is directly adjacent to the hand area of the cortex in the human brain. And even before my group came up with this hypothesis, it was argued the hand gesture theory of language origins, where it’s recognized that we humans, even as I talk to you and maybe as you talk to me, nobody can see us, but I’m using my hands to explain what I’m saying, is that we naturally use gesturing and learn gesturing. Each language has its own learned gestures of the hands.

0:29:06 SC: No, I absolutely do. I’m constantly apologizing for trying to explain things using my hands, as I know perfectly well that I’m on audio and not video. And also is this sort of the same fact or a related fact to the idea that the hand control part of your brain is near to the vocal control part?

0:29:29 EJ: Yeah, I think that’s partly the one explanation that could explain the use of hands, that they duplicated from the hand gesturing areas. So you can get Koko and other primates and some other animals to communicate with gestures using their hands or using their wings. And so yeah, maybe there’s a close relationship there and it’s maintained that relationship after it duplicated from that hand circuit.

0:29:58 SC: And I guess the part I’m missing is I totally think, although I understand the idea that there’s a motor control circuit, it gets duplicated, it helps us control our vocalizations, but its relationship to learning I guess I’m missing. Is it a particular kind of circuit that helps us learn, or is it just communicate and cooperate with other parts of the brain?

0:30:21 EJ: Yeah, I’m proposing this is a motor learning circuit, and what do I mean by motor learning? I mean learning, the brain controlling body part to learn how to move muscles in certain ways.

0:30:33 SC: I see, okay.

0:30:34 EJ: Learning how to play the piano with the fingers, learning how to walk or do dancing, right?

0:30:41 SC: Got it.

0:30:42 EJ: That this circuit exists, not exactly dancing to music, that’s another thing, but to learn, like circus animals learning how to do tricks, that learning how to move your body in different ways is now controlling the larynx.

0:30:57 SC: I see. Yeah, good. A lightbulb just went off in my brain. I mean, clearly, all these different kinds of species have some learning capacities, and clearly they also have some motor control capacities, but that doesn’t guarantee that they’re sort of linked up. Like we can’t control our heart rate or something like that, right?

0:31:13 EJ: Right, exactly.

0:31:14 SC: But you’re saying that we develop the ability to apply our learning abilities to our vocalization abilities.

0:31:20 EJ: That’s right, right, exactly. Using a similar type of muscle fibers, but now it’s muscles that produce the voice and produce sound.

0:31:30 SC: And it does seem still remarkable to me that it happens in such wildly different species as birds and humans. This is obviously a case of completely independent evolution, right?

0:31:41 EJ: Right, exactly. And I think that it’s kind of like you can get evolution to do the same thing multiple times, and it’s kind of like the evolution of wings. They evolve in bats and birds, some ancient flying dinosaurs, and each time it’s at the sides of the body, not one on the head, one on the foot or somewhere else, because the center of gravity, there’s this selection pressure. You need to have a center of gravity in the sky, you need something to be aerodynamic. So nature is selecting for this trait, and I think it’s the same thing when it comes to spoken language.

0:32:18 SC: Yeah, we’ve had some biologists, evolutionary biologists on the show before, and one of the themes that keeps coming up is on the one hand, evolution, natural selection involves some random changes, trying out new things, but on the other hand, there are still laws of physics and design principles and so forth, and so you need to find the right solution and it might be found in different times by different species.

0:32:40 EJ: Exactly. Exactly. And thinking about the laws of physics and so forth, when we came up with this motor theory of vocal learning origin and how it could have happened and also prove using the phylogenetic tree with whole genomes that this is independent origins of in birds and in mammals, it gave me more… A lightbulb went off in my head and said, “Heck, this has to mean that not only are there other planets but maybe there’s life on other planets… “

[chuckle]

0:33:14 EJ: Because if you’re starting from the same substrate and just can naturally evolve something as complex as spoken language, or at least something close to it, multiple times, why can’t you evolve something as complex as life multiple times?

0:33:29 SC: This is a very good question. We’ve also talked with origins of life people, so you’re now leaning toward the idea that life is ubiquitous in the universe? I know this is a little aside, but that’s okay. That’s what podcasts are for.

0:33:41 EJ: Yeah. I won’t go as far as saying ubiquitous, but I could go as far as saying as definitely more than an N of 1.

0:33:48 SC: Right, okay. There’s the big idea that maybe there’s monocellular life all over the place, but it never got together to make multicellular life.

0:33:57 EJ: Okay. I find that hard to believe, because cells like to communicate with each other and they like to aggregate, so it’d have to be monocellular life that does not have the selection for a multicellular need.

0:34:13 SC: Yeah, yeah. It took a long time, though, on Earth. Life came to be pretty quickly but the grouping together took a long time.

0:34:21 EJ: I would agree with that. So… So, yeah, it’s not a straightforward linear function over time, as to getting to the more complex life form we are now.

0:34:29 SC: Yeah.

0:34:30 EJ: I just wish we humans, we’d evolve a little faster considering our current politics.

0:34:35 SC: Yeah. There are things we… But evolution is not directed, as you know, so maybe evolving is not what we want to do.

0:34:42 EJ: Right.

0:34:43 SC: But okay, so back to the birds. Just to drive it home, the fact that it’s whales and elephants and humans that can vocal learn clearly means that they don’t have a common ancestor, it evolved independently within those mammals. Did the vocal learning also evolve independently within the different bird species where it happens?

0:35:05 EJ: I would say we don’t have evidence that vocal learning involved within the different bird species. We do have the evidence that it was lost in some, like the Anna’s hummingbird, and that it was lost in females of a number of songbird species. And this is why there are some species out there, and we humans in the northern hemisphere think that in most species only the males sing and the females don’t. It turns out, the Equator, where most songbirds are at, adult males and females learn how to sing. The further you get away from the Equator, to higher probability that females lost the ability, where there has been more of a division of labor between the sexes.

0:35:44 SC: It’s interesting, yeah, that we will learn something that useful and then lose it. Maybe this goes back your ideas about, I guess… Could I put your idea that the predators in the phrasing it as, there’s a resource cost in being able to have vocal learning…

0:36:01 EJ: Yeah.

0:36:01 SC: And you have to decide whether it’s worth it to your situation?

0:36:04 EJ: Exactly. And that resource comes in two forms. One is, like I said, for the predators, you’ll just be dead, and the other is, it takes a lot of energy, glucose, ATP, and so forth, in this brain circuit, which has very high firing rates. And one of the reasons why I think that’s the case is because the larynx muscles, besides the lateral active muscles, the larynx muscles are the most rapidly firing muscles in the body. So I think it takes a lot of actual real energy for the body to actually produce spoken language.

0:36:42 SC: And what is it that is the benefit to a hummingbird or a parakeet to be able to do this? Do they vocally learn and use that in social contexts to team up?

0:36:55 EJ: They do use it in social contexts, most species us it for mate attraction and territorial defense. The more varied your vocalizations, the more likely you are to attract a mate, because the more intelligent you sound, the more healthier you sound.

0:37:08 SC: Is that the way it works? Okay.

0:37:09 EJ: [0:37:09] ____ species like chickadees, they will have particular calls and learn calls and pitches of those calls that identify particular predators in the area, and you can get dolphins who will use what they call signature whistles with names for each other. So you can imagine, once you get this form of communication, it’s not visual, it’s auditory, but sound propagates a long distance so you can communicate with somebody a long distance without actually having to see them. You have a greater social network with this than you get from visual [0:37:49] ____ or smell.

0:37:51 SC: Actually, that makes me ask, is there a visual equivalent of this question about vocal learning? Is the ability to make gestures that have meaning something some species have and others don’t?

0:38:04 EJ: Yeah. So the visual equivalent would be sign gesturing, which can be learned. Like a zebra finch can learn… When it sings its learned song to a female, a male sings to a female, it produces some body movement that we call a courtship dance. That actual body movement is also learned. And you have that kind of learning in other species as well that don’t produce learned sounds. So yeah, there is visual learning through visual motor integration.

0:38:38 SC: Good.

0:38:39 EJ: But you need to see something close to you in order to see what that learned communication is.

0:38:45 SC: Sure. Yeah. And these days in the pandemic, who has time to look good and… [chuckle] be visually appealing, so I get that but…

0:38:54 EJ: But actually, to put it in another perspective, if we only could sign but can’t produce learned sounds, we couldn’t actually communicate with… If I’m in the kitchen and somebody else is in the bathroom, I can yell out to that person and say, “Hey, please bring me the towel from the bathroom.” But if I sign, do a sign, “Please bring me a towel from the bathroom,” that person can’t hear me.

0:39:22 SC: Yeah, but it’s sort of battling in my mind, the idea that it’s still so rare. It would seem like some herd of animals in the savannah would find it very, very useful to be able to warn about different things using actual symbolic language.

0:39:40 EJ: Right. Unless the predators pick them off.

0:39:42 SC: Yeah. So the predators are the ones who…

0:39:45 EJ: Yeah, that’s why I think there’s selection for it, and there is selection pressure against it.

0:39:50 SC: Yeah. Okay, good, good. So you mentioned the idea that it makes you sexier if you can talk and you have a sweet-tongued voice, etcetera, but my impression is that this is something that evolutionary biologists struggle with, the extent to which just being more attractive to mates is something that drives evolutionary pressures. Have we learned more about that since my vague learnings from years ago?

0:40:15 EJ: Yeah, there is debate about it. At the same time, I can understand the side of the debate that says propagating your species, the survival of your species, is being just as important as the survival as an individual. How do you make your species survive is you have sexual reproduction. So the competition for that survival of your own individual genes is high, and so anything that can help that, including sounding intelligent and sexy, I think will go a long way.

0:40:50 SC: Interesting. So that’s a major driver, do you think, not only in birds, but also in humans or in elephants?

0:40:58 EJ: Yeah. In humans. Yeah, because brain over brawn is a common statement. Both of them are seen as selection traits of how strong you are, as well as how intelligent you are. And that intelligence correlates with spoken language abilities. In birds, it’s been shown that… Stephen Nowicki at Duke University has shown that if you nutritionally deprive a songbird at a young age, and then it grows up to be an adult, it sings what sounds like maybe an impoverished song as a result of that nutritional deprivation, because that nutritional deprivation impacted the brain in a negative way. Females don’t like that impoverished song, and that bird doesn’t get to pass on its genes.

0:41:52 SC: We just talked to David Eagleman about how the brain is especially plastic at young ages, and how you learn things and then you lose the ability to learn them, so I guess what you’re saying is that songbirds also, they have a window in which they can learn and it goes away, maybe.

0:42:09 EJ: That’s right, that’s right. Yeah, this critical period like we humans have, when you learn best at an early age in life, and then it’s harder to learn new sounds later in life. And for some songbirds, they just can’t. And others, they are able to, like humans, but still not as good as when they are a young infant.

0:42:30 SC: In some sense, the fact that songbirds also have this ability to do vocal learning is a boon for scientists like you, because you can study the actual brains of songbirds with a lot less restriction than the brains of human beings or something like that.

0:42:44 EJ: That’s right. And in one form, you would think, well, it’s because it’s independent, it’s going to be different. And therefore it may not be relevant to a human spoken language, but we’re finding because things that evolve independently can evolve in a similar way, it does mean that since it’s similar, you can learn about the human mechanisms from studying these animals, and this is what we’ve been discovering.

0:43:12 SC: Right. So when you say that there is this motor circuit that helps us control our vocalizations and helps us learn, do we say it’s the same motor circuit in a parakeet, in a human, or similar, related?

0:43:27 EJ: No, we say it’s an analogous one. So the word analogy or analogous means that it’s independently evolved but in a similar way, and homologous means it’s the same. So in actuality, if this motor theory of vocal learning origin is true, it would mean that the surrounding motor circuit found in all vertebrates for learning how to move other parts of the body, that’s homology. And we would call that a deep homology, because it gave rise to the analogous circuit for speech.

0:44:03 SC: Okay, so there is an aspect that is homologous, which is the stronger form than simply analogous.

0:44:11 EJ: That’s right. Right. So the motor pathway for learning is homologous, deep homology, and the analogous one that it came out of is the speech pathway.

0:44:20 SC: Okay. Very good. And maybe let’s go into some details about how you know something like that. How do you learn what’s going on in the brain of a parakeet?

0:44:29 EJ: We have different kinds of experiments. One is people can put electrodes in the brain, like when patients are undergoing surgery, they put electrodes and they find out the speech areas, and they ask the person to speak, so they don’t want to remove that part of the brain. When a person is trying to remove a tumor or a reason that causes epilepsy, so you’d put electrodes and when a person speaks like we’re doing now, the neurons light up. The reaction potentials, electrical currents pass from one neuron to another that control that behavior, but you can do the same thing with these animals, and record while they’re singing.

0:45:08 EJ: The other is we have… There are certain genes in the brain that respond to that activity, that electrical [0:45:14] ____ changes in the brain. Their messenger RNA and protein products go up or down, and we can use this like a molecular mapping tool to identify brain areas that are active during particular behaviors.

0:45:29 SC: And how do you know what brain area is expressing a gene?

0:45:33 EJ: We do have… In that case we do have to dissect the brain out after they’re vocalizing, and we measure using techniques like immunocytochemistry, it’s called, or in situ hybridization. These are techniques where we take a probe in a test tube that we make to a particular gene, and then we bind it to the tissue. And we can measure the gene product with that probe, to find out what brain area was active.

0:46:00 SC: So maybe just for sort of intellectual interest reasons, it sounds like you have a lab, or maybe you have multiple labs and you’re doing all sorts of different kinds of things, sometimes you’re dissecting birds and sometimes you’re training them. What’s going on in the different parts of your lab?

0:46:16 EJ: Yeah. So I actually have three different lab spaces. One we call the neurogenetics of language lab, where here we’re trying to, and I’m sitting in my office of that lab now, where we try to figure out the genetics behind spoken language, what is setting up those brain circuits, what’s similar to what we see in the birds, what we can learn from the birds and humans. And the circuitry, the electrophysiological activity in them and the behavior. So we’re doing all of that, and on top of trying to figure out how it works, we have hypotheses of how it works, and what genes are specializing in the brain to make this work in humans and these songbirds. And what we’re trying to do is take the human version of those genes and put them in the mouse brain, a species that can’t imitate sounds the way we do. To test the hypothesis, if we take the human version of these genes that causes disconnectivity, will we get the mouse to actually learn how to imitate sounds?

0:47:17 SC: And the answer is?

0:47:19 EJ: We’re not there yet. So far we’ve modified one gene, and we don’t think it’s enough. We’ve got to modify dozens of genes, we think. We also have a genome… Go ahead.

0:47:32 SC: I’m just… I’m interested. So we find a gene in human beings that is related to our vocal learning capabilities and you’re inserting it, literally, into the mouse genome.

0:47:44 EJ: Yeah. So far, what we’re… Except for this SRGAP2 gene, which I don’t think is directly related to language, right, we’re not finding that humans and songbirds and parrots have extra genes that we think of as associated with language. We think it’s modification of existing genes. The only case that we’re looking for extra genes, could there be extra copies of a gene that cause a brain pathway duplication? But even if that were occurring, we’re seeing existing genes that we can find in mice, we can find in birds, we can find in reptiles and in fish, have been modified in a similar way in humans and songbirds.

0:48:21 SC: Okay, so that’s dramatic. I want to make sure that I’m not over-emphasizing. And so for one thing, I think maybe people don’t understand the extent to which there’s overlap between the genes of a songbird and the gene of a human being. How similar are those two things? ‘Cause they look different. A bird looks very different from a person.

0:48:41 EJ: Yeah. Even though a bird looks very different from a person, over 80% of our genes are the same genes. They’re just regulated in different ways and do have different protein-coding sequences to them as well, divergence in that… But they’re regulated in different ways that causes a bird to be a bird and a mammal to be a mammal.

0:49:02 SC: So when you say that the motor pathway is… Parts of it homologous, parts of it analogous between songbirds and humans, you can sort of pinpoint that at the gene level?

0:49:17 EJ: Yes, yes. Because while we can… Based upon the connectivity, we can tell where we can call this a motor pathway because it’s synapsing onto… It’s making connections to neurons that eventually control the muscles. The other is certain genes that are expressed in the motor pathway of birds, we can see it in the mammal brain as well. Mind you, I’m going to say that the bird brain, the organization of the cortex, part of the bird brain, they do have a cortex, but it’s not layered as it is in humans. The cells are actually clustered in their organization. So it actually has a different cellular organization, even though it’s an ancient motor-learning pathway.

0:49:57 SC: Right, got it. But it does raise this possibility, maybe this is what you already just said with the mice, that the same genes exist in all sorts of species that don’t have vocal learning, but if you can just fiddle with how they’re expressed or not, you can give them that ability.

0:50:14 EJ: That’s right, that’s right. So, some biologists like to think of this as the tool kit. Even though we have… A lot of species, including us, have these big giant genomes of lots of DNA, but only 20,000 protein-coding genes. If nature wanted to, it can fit 100 times that many genes inside our genome, with a lot of this intergenic regions for regulation and duplications for… Or just housing viruses and keeping them quiet in our genome. So nature has a way of taking a limited set of 20,000 genes as a tool kit. Think about 20,000 tools and then use them in different ways to control different kind of connections in the brain, or different kinds of cell types in the body.

0:51:06 SC: Right. I think this was one of the points made by my evil twin, Sean B. Carroll. We had him on the podcast.

0:51:12 EJ: Yes. I know who he is. Yes.

[laughter]

0:51:15 SC: He talks about the tool kit. Now it’s the same tool kit? You mean the same thing?

0:51:19 EJ: That’s right. So the same tool kit is being used to generate the spoken language pathway.

0:51:23 SC: I see. Okay. So now you’re making super mice that can talk to each other and plot our ultimate downfall.

[chuckle]

0:51:33 EJ: Well, think about this, parrots can also imitate us and they’re apparently not taking over the world, at least not yet.

0:51:36 SC: That’s true, that’s true. But the mice… Yeah, yeah, I don’t know. I worry about the mice a little bit. But okay, but these are early days with the mice. You’re trying to explore how you can… How do you do it? What exactly do you fiddle with in the genome? Is it… Do you change the gene somewhere to change the expression elsewhere or do you just put different chemicals in the environment?

0:51:56 EJ: We’re trying to change the expression locally in the circuits in the brain that control vocal behavior, and not change it elsewhere. And so we’re trying to up-regulate or down-regulate certain gene products that control connections. And the one connection we’re trying to modify the most is one that the cortex in the forebrain has a direct control of the neurons that modulate the muscles for vocalizations. In other species we don’t get that direct connection, or even any connection at all. In humans and songbirds it’s a huge, robust connection from the forebrain.

0:52:31 SC: Okay. So it’s sorta a target to shoot for in some sense.

0:52:35 EJ: That’s right. We have targeted connections we’re trying to change in the brain.

0:52:39 SC: And all this sounds, from the point of view of any scientists= 20 years ago, to be incredibly science fictiony, the ability to really go in there and zero in on genes and turn them on and off is rapid progress in the field as far as I can tell.

0:52:54 EJ: Yes, and I would still say at this point, it’s still science fictiony to me, but I’ve been able, and other colleagues of mine have been able to come up with clear hypotheses that, if tested and work out, actually will get us there, if things really work this way. Twenty years ago we didn’t have a clear hypothesis. So now, based upon the data we’ve collected and other labs have collected, we can formulate this hypothesis and say, “Wow, this is a crazy idea, but let’s go ahead and get some people to give us money to try it.” And that’s what has happened.

0:53:32 SC: Well, we’ve had the human genome project, but we don’t have the entire animal kingdom genome project yet. Is that something that we’re thinking about?

0:53:41 EJ: Well, yes, about the lab spaces I have and all these questions have now led to one lab space. My second lab space is a vertebrate genome lab being run by, with me, and another colleague, Olivier Fedrigo. And there, guess what, I’ve now become chair of a large international consortium whose mission it is to sequence the genomes of all vertebrate species on the planet, so all animals.

0:54:07 SC: Oh, okay. Wow.

0:54:07 EJ: 70,000 of them. And to do it at high quality, because we’ve found that if you don’t have high quality genomes, meaning that pieces are assembled correctly without gaps and without errors in them, you can do better biological investigations. And I said, “Why not just do that, not only for the vocal learners, but let’s just do it for all species on the planet.”

0:54:29 SC: And then you can… Presumably this is a giant database, this is just enormous amount of computational resources, yeah.

0:54:36 EJ: That’s right, exactly. So we don’t have the computational ability to do all of that right now. We don’t have the money to actually generate all the data, but we have a will and we have a path forward. And we now are in phase 1 of 260 species representing all vertebrate orders where we have found the money for that first phase. And we’re going to use that as a sounding board to say, “Hey, world, please give us the rest of the money to complete the entire project.” And eventually not for just all vertebrates, for an earth file genome project being led by Harris Lewin for all eukaryotic species on the planet.

0:55:14 SC: Eukaryotic species. Okay, so we’ll count as insects…

0:55:17 EJ: That’s right.

0:55:18 SC: Right. And so, just again, for the cultural enrichment purposes, my scientific life, my team is typically me and a postdoc and a few students. How big is all of these labs that you have and are trying to control?

0:55:34 EJ: Yeah. And I do have one more, which is a field research center upstate New York, part of the Rockefeller University, where we do field work on different species, recording their songs in the wild and looking at the different species have different repertoire compositions. Some are more complex than… Many, 100 songs, some just sing one. And so I would say my team, amongst these three lab spaces, is a total close to 30 people, with the neuroscience space being at least half, more than half of those people. And the international consortiums that I’m part of for the vertebrate genomes project, earth file genome project, and also one for collaborating on brain evolution across species with the Allen Institute and others, each one of those… Well, the genome one itself alone is well over 200 people in 80 countries as of right now, and it grows every week. And the neuroscience brain evolution one is like four labs, each one of them having anywhere from seven to… My lab having 30 people, and the Allen Institute, they have hundreds.

0:56:52 SC: Yeah, you’re not quite up to the level of the experimental particle physicists with 5000 people on a collaboration, but it’s clear that’s the direction in which things are going.

0:57:00 EJ: But I’ve taken some inspiration from them. I was invited a few years ago to the American Astronomical Society to give a keynote lecture on the evolution of language. And I’m like, “Why do astronomers want to know about the brain and how it evolved and so forth?” And I can see why now, when I came up with this idea of thinking that life is on other planets, when I can understand how language evolves more than once.

0:57:25 SC: Yeah, yeah, exactly. That’s right. And what is the… What kinds of things can we learn once we get the entire vertebrate genome or the set of them all sequenced? What are the questions you’re immediately asking comparing between species?

0:57:39 EJ: Yeah, so that’s what I’ve been hoping is that there are going to be questions that people will think of that they never would think of before, because they never thought in their lifetime, not only having a human genome, they have the genome of all life on earth. And so it’ll become… You don’t have to sequence anymore, what we’ll need to do is create a database of traits of all these different species. And with a database of traits and a database of their genetic codes, that’ll make it a lot easier to figure out what kind of genes you need to create certain drugs against certain diseases, because there would be lots of species that are resistant to a disease and others that are not. And you’ll be able to figure that out relatively quickly with that information.

0:58:28 EJ: I think we’ll be able to define what is really a species, and when to call a species a species, as opposed to a subspecies or a strain. I think we’ll be able to really understand evolution a lot better than we do now, and we’ll be able to really figure out the Tree of Life a lot more accurately than we have now.

0:58:54 SC: So for example, I thought that the Tree of Life is something we understood pretty well, are we still lacking in certain important aspects there?

0:59:02 EJ: Yes, I thought we did too, until I discovered that these vocal learning species all have, like I said, especially amongst the birds, very similar brain pathways. That started, me and other people, questioning, “Did they have a single origin?” And for the songbirds, parrots and hummingbirds. And so when I started then looking at the literature, and every year, every other year, the bird tree, the family tree of birds, is changing. Owls going from one position to another, hummingbirds was going from one position to another, and I said, “Wait a minute, these guys don’t know what they’re talking about.” The tree is not really set. And that’s when we decided to do whole genomes, and we changed the bird tree once again, which is now more stable, and it’s in the publication since we have the whole genome. So no, the Tree of Life is not resolved. It’s far from resolved.

0:59:57 SC: But the genome project would be exactly the kind of thing you need to do that. You don’t even sort of need to look at what they look like anymore, you can just trace in the genomes what came from what, is that a safe way to see it?

1:00:07 EJ: That’s right.

1:00:07 SC: Okay.

1:00:08 EJ: That’s right. And it’s not going to be a straightforward, what we call bifurcating tree, where you have parents give rise to children, who… Or you can go from the children to the parents and their grandparents and so forth. There’s going to be inter-relationships, and so it’s going to be partially network-like, and the way I’ll put that in for humans, even amongst the vocal learning species as well, but for humans, is that, you’re not my father or my parent, and so forth, right, but we’re all cousins.

1:00:42 SC: Yeah.

1:00:42 EJ: People don’t realize we’re all cousins, we’re all related to each other by being cousins. And if we sequence the genome of every person on the planet, we can figure out what our cousin relationships are to everybody else.

1:00:56 SC: Right. And when we… Because I’m again, naive about this, when we get the genome for a species, like when I first heard that we were doing the Human Genome Project, my reaction was, “But human beings have different genomes.” Right? “We’re genetically not identical to each other.” And is the difference that there are certain broad genes that we do exactly share and then there are minor differences here and there, do we map down to the individual base pairs of DNA or is it cruder than that?

1:01:24 EJ: Yeah, and that’s another project that I got involved with as well, called the Pan-Human Genome Project, where we predict if you sequence the genomes of about 300 people, representing roughly 350 different populations or ethnic groups on the planet, that you’ll basically determine what is the conserved human genome that everybody shares and then what is different…

1:01:50 SC: Right, good.

1:01:50 EJ: From one group to another. And we don’t know the answer to that. Like how much… What is the percent that is unequivocally human that will… That once that sequence changes, we’re no longer human. And we’re getting close to knowing that, but we don’t really know the answer to be able for me to answer that question in a percentage manner, but we do know that it has to exist.

1:02:14 SC: Right. What is the other primate that is probably closest to human beings, genetically?

1:02:20 EJ: Chimpanzee is the closest relative, the closest living relative.

1:02:24 SC: Okay. And so then the other thing we’d want to know is how different we are from the chimpanzees, not just how different we are from each other, right? There are some genes that are probably always different between humans and chimpanzees, but always the same among humans.

1:02:36 EJ: That’s right. And one of those is the SRGAP2 gene that I mentioned to you, that keeps our brain in a more immature state compared to chimpanzees and other animals. Another one close to home for me is FOXP2. It’s a transcription factor that regulates other genes, that it has two nucleotide mutations, just two amino acid differences that you don’t see in chimps or most other vertebrate species that we think somehow enhances spoken language [1:03:08] ____ to function the way they do.

1:03:11 SC: To what extent can we think about spoken language as the thing that makes us special? It’s clearly one of the things. Do you think that it is one of the main things that really set humans on this slightly different trajectory?

1:03:26 EJ: Yeah, so you asked about, a little while ago, about the… Even amongst the vocal learners, are there differences? And there are. And so I think it’s… There are differences of degree for almost everything, and that includes spoken language, so we are special for spoken language, but the specialty is not have and have not, okay? The specialty is that we’re much more far advanced for this ability than even the other vocal learners.

1:03:56 SC: So we’re just better at making the sounds or creating them in different patterns?

1:04:02 EJ: Yeah, we’re better at making… I won’t say exactly better at making them because you can get some parrots producing sounds in ways we can’t…

1:04:09 SC: Yeah, that’s true.

1:04:10 EJ: Right? And I challenge anybody to produce parrot wobble song with their vocal learning abilities, but we are better at recombining them and better at using our sounds for various different things, like writing, reading, forming new concepts, and so on.

1:04:30 SC: Given everything that you’ve learned about language and vocal learning, what does this teach us about old ideas from Noam Chomsky or what I learned about from Steven Pinker’s books about the language instinct, is that a good way of thinking about things, that we have some built-in grammar choices in our brain or is that kind of outdated?

1:04:49 EJ: There are two things coming from those two people and also the linguistic community in general, the language instinct, this… There is a truth to that in the sense that we have a genetic predisposition to learn how to imitate sounds. The brain pathway that controls spoken language is genetically determined. What it does and what it imitates is not genetically determined, that we learn culturally.

1:05:17 SC: Right.

1:05:19 EJ: So the second thing is coming out of Chomsky is that there’s a language module in the brain that then controls the vocal pathway and the auditory pathway, telling it what to do and how to process speech and sounds. I disagree with that. I don’t think there’s good evidence for a separate language module. I think the brain pathway that’s actually controlling the grammar, the syntax, and the… And so forth, is the spoken language pathway itself, is the motor learning pathway that I’ve talked about this whole time. And the other pathway that controls perception of the sounds is the auditory pathway, including Wernicke’s area, that I believe exists in all these vertebrate species, at least dogs and Koko and chickens and so forth. And this is not unique, it’s already there. It feeds into our motor learning pathway but it’s already there, and it’s not a separate language module. And this is why dogs can understand rudimentary human speech.

1:06:15 SC: Okay. I guess this is… This is a good place to sort of wind things down. We let our hair down at the end of the podcast and think about the relationship between language and intelligence more broadly. The first thing that people would say, if you said what makes human beings different than other animals, is that we’re smarter, right? But clearly this language ability that we share with this kind of somewhat random collection of other animals is also kind of important. Is there some… What is the right word… Evolutionary pressure that sort of increases intelligence because we learn these vocal abilities or vice versa, or what’s going on?

1:06:58 EJ: Yeah. I’m going to say, I’m not going to put a whole lot of confidence in what I’m about to say, but I’m going to say it still hasn’t been disproven and it’s worth testing further, and I won’t be the first to say this. But I’m going to say it in more in a unique way, and that is, I don’t think it’s… I don’t want to call it language ability associated with greater intelligence, I’m going to call it vocal learning ability associated with greater intelligence, and then why that could have occurred, is that vocal learning leads to greater social communication. And greater social communication, I think then selects for greater intelligence, in that sequence of order. And that the language ability, in other words, the ability to communicate in a syntactical meaning, manner with sign gesturing or even olfaction or vision, already exists in many species, but I don’t think it’s selecting for greater intelligence. I think it’s particularly the vocal learned communication that’s selecting for it.

1:08:00 SC: I guess maybe… Let’s throw something out there. In the list of other species that have this vocal learning ability, whether it’s elephants or bats or whales or birds, we’re the only ones that have fingers, whereas other primates have fingers, or even other mammals have fingers and can grasp things, but they don’t have vocal learning. Is there some combination of this ability to speak and learn language sounds but then also be able to manipulate our environment in delicate ways that maybe makes intelligence a useful quality in ways that it’s less obviously useful to evolution in other contexts?

1:08:41 EJ: That’s an interesting… I haven’t thought about that. This is the very first time somebody has even brought that idea to me. That’s an interesting idea. I like it that… That in addition to our greater social communication through vocal learning, we do now use our hands in a manipulative way, that can manipulate the environment more than the other vocal learners. And if parrots had hands, maybe they would be able to take over the world.

1:09:08 SC: They can fly, they can clearly take over the world much more easily than we can if they could build things.

1:09:14 EJ: Right. That’s not a… That’s even a more hand-waving idea, but I don’t want to shoot it down, I think that’s a plausible thing to ponder on more.

1:09:27 SC: Well, in that case, I definitely want to end this podcast, because this is a high note that we’re not… We’re not going to get higher than. But I’d like… Maybe I’ll give you the last word here, but one of the things about evolution is not just that there are random mutations and it leads us crazy places, but that there are weird synchronizations, as was already said, between different things, whether it’s having fingers and vocalizing and learning and so forth, and… What is the role of abstract thought in all of this? Is this something that is unique to humans, and if we give some credit to our ability to vocalize, or is this once again something where we’re just giving ourselves too much credit because we’re ourselves?

1:10:10 EJ: I think this is one of those things where the truth is in the middle, that we do give ourselves too much credit for, but I do think we have a greater capacity for abstract thought, and the reason why is that I think thought is happening in our auditory or visual pathways as well as in our speech pathways. And when we have thought through our speech pathways, we are talking to ourselves, we’re not actually producing the sounds, but we’re talking in our head, and that speech that’s being produced in our head is being sent to the hearing pathway, the auditory pathway, to hear what we say. So we have this greater capacity for thinking, but I don’t think we’re the only ones with that ability. And so I think parrots will talk in their own heads, but a dog will only hear in its own head, it won’t talk in its own head.

1:10:56 SC: Wow, that’s fascinating. It’s a really, really good way to put it. On an earlier podcast with Karl Friston, I contrasted my two cats, because I think they have very different intellectual abilities. One really seems to have an inner life and the other one doesn’t, so… [chuckle] I think that… I hope that biologists and neuroscientists like yourself can learn more about the inner lives of all sorts of animals going forward.

1:11:20 EJ: If we can get them to talk we could be able to do that.

1:11:22 SC: Well, you’re going to change their genome so they can do that. That’s going to revolutionize the world. Alright, Erich Jarvis, thanks very much. This was a fascinating conversation. Thanks for being on Mindscape.

1:11:31 EJ: You’re welcome.

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