- A song sparrow will have like... (whistles) Or... (whistles) - Wait a minute, man.

You speak bird?

- I try to whistle bird, yes.

- You speak bird?

(both laughing) (upbeat music) Erich, welcome to "Particles of Thought."

You do some fascinating research that involves understanding how the brain works, understanding how language works, and you study non-human animals to figure out how humans work.

- Mm-hmm.

Yep.

- Yeah.

So go into that a little bit for me.

- Yeah, so the brain does many fascinating things.

And humans have one fascinating thing that the brain does that you don't find in many other species, and that is language, particularly spoken language.

And one of the components that give rise to spoken language is the ability to imitate sounds.

The words that I'm saying now are imitated sounds.

And guess what?

There are very few species that have it, but they're out there.

Parrots is one of them.

Many people know that parrots can imitate, songbirds as well, hummingbirds, amongst birds.

And amongst mammals, besides us humans, we got dolphins, whales, sea lions, and bats.

- [Hakeem] Oh, wow.

- And some say elephants as well.

And then that's it that's been found so far.

- That's a bigger list than I think most people would appreciate.

- Yeah, yep.

That's right.

Yep.

- So, all right.

So we have, for example, dogs that seem to understand certain vocalizations that we make.

- Yes.

Yes.

- But we don't ever expect for them to be able to vocalize themselves, right?

- Right.

Right.

- So is it completely two different areas of the brain?

- Yeah.

See, this is what a lot of, actually not even of people in the public, but academic scientists don't get, you know, that when we talk about language, as I was saying earlier, there are multiple components.

And a lot of people think all those components, even if they think about them, they think that they're all unique to humans.

They're not.

And so the ability to understand spoken language actually is more widespread than people think.

- [Hakeem] Yeah.

- And you just gotta go to your pet animals, particularly dogs.

Dogs can understand the word sit or (speaks in Spanish) in Spanish, or (speaks in Japanese) in Japanese.

Dogs aren't born to understand Japanese or English.

Right?

- Right, right, right.

Yeah, yeah.

- Or even whole sentences: "Get the newspaper.

Get my ball," you know?

"Wanna go outside?

Wanna to be petted?"

They understand all these words, several hundred, you know, words- - [Hakeem] Interesting.

- But they can't say it, you know?

- Right.

- The best you can get out of a dog is trying to modify its vocal tract to say (mimics dog yapping), you know?

- Right, right, right.

Yeah, I've seen those.

- And that's good, you know?

- Yeah.

Yeah.

- And I would consider this like a semi-continuum of vocal learning.

They have very limited ability.

- But they do what you brought up earlier, which is imitating sound, right?

- Yeah, yeah.

Getting close to saying something that sounds like an imitated sound, but not full-blown imitation like we see in humans and parrots and songbirds.

- Right, right.

- So you asked about the brain pathways, yes.

- Right.

- And when you look in the brain, the brain areas involved in understanding speech, your hearing brain circuits, is separate from the brain pathway producing that speech.

- [Hakeem] I see.

- And when we look in the brain of various different species, we humans, parrots, and songbirds have brain areas for both hearing and processing speech-like sounds and producing them, but dogs only have the brain areas for hearing them.

- Oh.

- They don't have the brain pathway that goes to the larynx to control the imitation of those sounds.

- Wow.

- Yeah.

- Okay.

So they're just missing it.

- They're missing it.

Or it could be very rudimentary.

We think we found a very rudimentary circuit in mice, so I wouldn't be surprised if it's, they're in dogs.

But it's not this full-blown, advanced circuit that we find in humans and the other vocal learning species.

- Okay, so that brings me to another research study that I heard, I think, a year ago.

I don't think the result was a year ago.

I think I heard someone speaking of it a year ago.

And what that was is that it was originally thought that chimpanzees don't have the mechanical equipment for producing speech.

But then some study found, well, actually they do, they just don't have the brain for it.

- That's right.

That's right.

Yes.

- Okay.

- Yeah, this has been a debate over a number of years, and it includes, you know, what in biology, in the brain, in the muscles and so forth, makes speech special?

And there are a number of different hypotheses, and this is one of them, that there's a difference in the musculature of the larynx, or that it's more descended in humans, allowing greater airspace in the vocal tract to produce a greater variety of sounds.

A lot of this has been proven not to be the case.

- Ah.

- All right?

- So a colleague of mine, Tecumseh Fitch, blows air through post-mortem, you know, larynxes of humans, of chimpanzees, of monkeys.

And you get similar kinds of sounds that you get in speech when you, you know, phonemes we call them, different kinds of phonemes, that you get when you blow air even through a post-mortem larynx.

But when it's inside the living animal of a monkey, you can't get the speech sounds out of it.

And why?

Because it's not in the muscles, it's in the brain that makes that difference between being able to speak and not speak.

- So is it the case that... You know, you have birds, you have mammals, you know, a different part of the family tree, so are the same outcomes being achieved by different brain areas?

Or is it that there's some ancient ancestor that predates birds and mammals that had this particular equipment and now it's being used in different ways to get the- - Yep.

Well, discovering these gene specializations, where the regulation is different, helped us answer some of the questions that you just asked.

And putting it all together, the story that, you know, I've come up with is that all vertebrates have the ability to learn how to move.

And what happened in us humans and the song learning birds, dolphins, I believe, as well, is that these brain pathways that control learned movement of the body are duplicating themselves to control the hands, the chest, the feet, and so forth during embryonic development.

And in us humans and the vocal learning birds, the brain pathway duplicated one more time and now got hooked up to the muscles of the larynx and the jaw and so forth to control sound production, to learn how to imitate sounds.

And we already have auditory input from the hearing pathway going into the movement pathway.

If you're gonna learn how to move, you gotta learn to move to the sounds that you hear, learn to move away from sounds and so forth.

- [Hakeem] Right.

- And so this auditory input is already happening.

- [Hakeem] Yeah.

- The ability to understand complex sounds is already there.

- Yeah.

- All right?

I think consciousness is already there.

And yes, language evolved more recently, spoken language.

So we call this brain evolution by brain pathway duplication.

Like gene duplication, a whole brain pathway duplicates, connects to the vocal organs, and now you get spoken, like, speech, basically- - Holy cow.

- And spoken language.

- Talking about taking something that already exists and- - Yeah.

- Yeah, yeah.

- And so this happened multiple times.

And when, each time that it happened, a certain set of genes change in their regulation in humans and in the song learning birds.

We call that convergent evolution.

- [Hakeem] Right.

- All right?

Because their closest relatives... Like us, for chimpanzees, we are their closest relatives.

I mean, they're our closest relative too.

You know, so chimpanzees- - Right.

Right.

Living, surviving relatives.

- The surviving- - The closest surviving relatives.

Yeah, yeah, yeah.

- That's right.

Let's say what we call suboscine birds for songbirds, or falcons for parrots, none of them have these brain pathways or this gene expression specializations that we see in the vocal learning birds.

So we think the whole brain pathway duplicated, the gene specializations then were evolved in a convergent manner.

- [Hakeem] I see.

- And so it suggests that if vocal learning and spoken language were to evolve another half a million years from now, say, in a crocodile- - Yeah.

- Right?

- Yeah.

- Or a chimpanzee, I could tell you what the brain pathways are gonna look like and I can tell you which genes are gonna change.

- It's predictable.

- It's predictable.

- Wow.

- That's right.

- Because you know what the rough material they have to start with is already.

- That's right.

- Yeah.

Yeah.

- Well, because we've already seen it multiple times in multiple lineages of species that there seems to be a basic principle of a fundamental set of genes that needs to change in order to get vocal imitation.

- Right.

- All right?

And in the songbirds, that was like 30 million years ago.

In parrots, that was 50 million years ago.

In humans, it was, the most, a million years ago, I think, with some common ancestors, with Neanderthal and Denisovan, archaic humans.

- So it would have been Homo Erectus then that had language first?

- We might go that far back.

That would be a prediction.

But certainly, you know, the hominids, as we call them, which are modern humans and archaic humans.

- Right, right, right.

Wow.

So you brought up this idea between hearing, speech, and motion.

So this is something... My niece was was born in 1984, when I was in high school.

And, you know, and rap was new.

So I used to sit around (table thumping) beating out beats.

And my little niece, as soon as she could sit up, she would bop and dance to the little beats I was making.

And at the time, I was a high school musician as well, it occurred to me, I was like, "What is this thing with music?

Why is it that we respond in such a way?"

We get emotional.

Our bodies move, almost without us thinking about it, to these sounds.

Like, what the hell is going on?

Why?

Because it seems like a lot of species are completely, they don't respond that way, right?

Right?

- Yep.

- Have you guys figured that out?

What's the- - Yeah.

One of the remarkable things, the discoveries in the last, you know, 10 to 15 years is that it's been found that only vocal learning species can learn how to dance.

And when I say dance, I mean rhythmically to a beat of sound and music.

And why is that the case?

- [Hakeem] Yeah.

- In order to evolve the ability to imitate sounds, you need the auditory input going through your ears to have rapid integration with the movement pathway that's controlling your muscles to produce those sounds.

All right?

You need that tight auditory motor integration, as we call it.

I think that once that tight integration occurred for the vocal organs, it contaminated the rest of the movement pathway to now process sound in a way that controls movement or influences movement of the other organs, of the other body parts, muscles that control the body, the arms, the legs.

And so, yes.

(table thumping) You know, your little niece, right, had something special going on that they find in these humans and other vocal learning species.

And so I think it's a side effect of having vocal learning.

The ability to dance came about because of our ability to speak.

- Wow.

- Yeah.

- That is so deep.

- And what's remarkable is that there are several kinds of abilities that came along either for the ride or that are evolved, that are correlated with our ability to speak.

And that's one of them, is the ability to dance synchronously to a beat of music.

Another is problem solving.

- Interesting.

- We found that the more advanced vocal learning abilities you find, let's say, in a songbird species, the better you are at problem solving.

All right?

- Interesting.

- And so there's some cognitive ability there.

And putting all this together, these abilities that are special in vocal learners, I call it the vocal learning cognitive complex, and I'm including dancing in that cognitive complex.

- Wow.

Wow.

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(graphic whooshes) Okay, so if I give you a random genome and I say, "Can this species do vocal learning?

Can this species do auditory learning?

Can this species produce a range of sounds?"

Could you tell all of that just from the genome?

- We're trying to do such tests now.

- Because here's where this is going, man.

I'm like, you know,, we got these other human species, Heidelbergensis, Denisovan, Floresiensis, Neanderthals, you know, you have access to their DNA- - That's right.

- So you might be able to know whether or not they had speech.

- That's right.

- And even though it's make-believe of getting the DNA out of the mosquito in the amber, what if there were, like, dinosaur species that could have similar properties?

'Cause birds descended from them, right?

- That's right.

That's right.

- Yeah, yeah, yeah.

- So to be able to ask such questions, we have to have the genetic data of all these species.

- [Hakeem] Right, right.

- And so I'm, also help leading several large-scale projects to sequence the genomes of all vertebrate species on the planet, like, all 70,000, and eventually a sequence of genomes of all 1.8 million eukaryotic species that have a nuclear membrane.

- Oh, wow.

Right, right.

- And from those genomes, we're gonna be interrogating them.

Do they have some of the same genetic differences we see in vocal learning species?

- [Hakeem] Right, right, right.

- And so far, we found that genetic differences in humans and some songbirds that are associated with vocal learning, we find them in Neanderthal sequences.

- Ah.

- Okay?

So that's what makes me say archaic humans, Neanderthals, probably had spoken language.

- Wow.

Wow.

- Yeah.

- So, you know, when you mentioned up the idea of dance coming from language, it made me think, you know, 'cause sometimes, you know, we have the genetic story and we have the archeological story.

And I remember there being some statement of there being a flute that was found and thought to be Neanderthal, an ancient flute.

So does that equal, if you have music, then that means that you actually had speech?

- Yeah.

Yeah.

So let me answer.

All those questions, I'm gonna keep in my mind.

One is the music speech.

I and a number of other people think that vocal learning in humans and songbirds, other species, evolved first for singing, and for singing for the purposes of mate attraction, territorial defense, keeping a group of individuals in a cohesive communicating manner, and then later became used for things like we're doing now, like abstract communication.

- So singing preceded speaking.

- I believe singing preceded speaking and that the same brain areas that control speaking is used for singing as well.

The right side is more dominant for singing.

The left side is more... Ah, that's my left.

Sorry.

The left side is more dominant for speech and the right side more dominant for singing.

- [Hakeem] Interesting.

- So that was one question.

The other asked, earlier, about the dinosaurs.

And so I mentioned Neanderthal genomic sequences.

- [Hakeem] Right, yeah.

- DNA in fossils, or let's say amber, or something frozen, you know, in the frozen tundra up north, only lasts for a certain number of years.

To go back to the time of dinosaurs, you know, no one's found DNA yet.

- Yeah, I know that it hasn't- - But let's say theoretically one day it happens- - Yeah, yeah.

- And we sequence that DNA?

Yes, I think we'll be able to tell you whether that dinosaur was a vocal learner or not.

And is it possible even without it?

The answer is yes.

Songbirds are dinosaurs, parrots are dinosaurs.

All birds are the only surviving dinosaurs that survived the last mass extinction.

So if the bird dinosaurs had vocal learning abilities, why not some of the others?

- Right, right, right.

- Tyrannosaurus?

- That would be a wonderful world, right?

We went from these depictions of dinosaurs that were basically like, "Hey, let's just wrap skin around a skeleton," that's what they are.

- That's right.

- Then eventually, you know, we're like, "Oh, maybe they had fat."

Then it's like, "Oh, maybe they had colors and feathers," and now they're singing.

- That's right.

That is... (both laughing) - That is amazing.

- Yeah.

We humans tend to denigrate other species, whether living or ancient species, extinct ones, we tend to denigrate them to put ourselves at a higher status.

- Right.

Yeah.

- But when you actually study them, you start to learn that there are many other species that are smart, that are good-looking, that are, you know, have abilities even beyond humans, and that there's a greater diversity out there than we appreciate.

And if you don't come to that realization, you're hurting your ability to actually learn something, the truth, about non-human species.

- Yeah, yeah, yeah.

You got to be completely open-minded, right?

- Yep.

That's right.

- You have to be completely open-minded, let the data do the talking, and, you know, hopefully you can ask great questions.

- Yep.

- We now have the ability to edit genes.

- Mm-hmm.

Yep.

- Can you engineer speech into species or vocal learning into species?

- This is exactly what we're trying.

Yes.

So, trying it for several reasons.

I mean, of course, there's the cool factor.

Can you- - Right, "Planet of the Apes."

- Can you- - Becoming real, yeah.

- Yeah, I'm not sure if that'll happen in my lifetime, but it's theoretically possible.

It's theoretically possible, yes.

- [Hakeem] Right, right.

- And so, even number of years ago, when we started coming up with hypotheses about how could song pathways in songbirds and human speech areas convergently evolve to function in a similar way with a similar set of genetic changes?

And what are the function of these genes in vocal learning?

So we would love to genetically modify these genes in a human and test what they do.

But that's tricky and unethical to a certain degree.

And we would love to do it in a songbird as well, but the genetic tools to manipulate genes in songbirds is not as advanced as we can do in mice.

- Oh, I see.

I see.

- And so what we're trying to do, and what we are doing, is taking a gene variance that we find in humans, that is either unique to humans or unique to vocal learning species, and gene editing them into the mouse genome.

What are we looking for?

We're looking for changes in the vocalizations in two characteristics.

- Our words are made up of phonemes, eh, ah, oh, ou, and we sequence those phonemes together to make words and then we sequence those words together to make sentences.

We call those sequences and the rules in which they're based syntax.

- Got it.

- Okay?

- Well, guess what?

These mice and other species, they have individual phonemes, or syllables is another name that we call them, and what is learned is the sequences, okay?

And you can change around the sequences.

Sometimes those sequences are innate.

- [Hakeem] Yeah.

- In us, we can actually have learned sequences of sounds that make words and make sentences.

And so what we're looking for is changes to those sequences as well as to the individual structure of the phonemes.

- I see.

So let me ask you a question about the sequences right quick.

So if there's a particular mouse that makes vocalizations and you record that, is it the case that you find repetitions of the same sequence?

- Yes.

- Oh.

- Yeah.

Yeah.

And they're repetitions of the same sequences that are innate, okay?

- So every other mouse will share those?

- Every other mouse will share them.

- Oh.

- And what we're trying to do is to see if we can get the mouse to learn new sequences or change the acoustic structure of each syllable within the sequence.

- So is it incredibly subtle, where it's not obvious to the ear, you have to do some, take the waveform of this recording and- - Yeah.

The changes we're seeing thus far, like, with changing one gene at a time, are on the subtle side, but in the direction one would predict.

- Ah, interesting.

- So, like, we recently published on a, working with Bob Darnell at Rockefeller, recently published on a study where a NOVA1 gene, it's a gene that controls splicing of, cutting up RNA molecules and re-putting them back together.

There's a human variant that you don't even find in Neanderthal.

And we put this human variant in the mouse genome and these mice start producing more complex syllables.

- [Hakeem] Oh, interesting.

Interesting.

- All right?

Another gene called Plexin-A1.

It's a gene that controls connectivity in the brain, and we see- - Connectivity between neurons?

- Between neurons.

And this gene actually is turned down in the human speech-motor cortex.

All right?

It's not one that's turned up.

It's turned down.

And when it gets turned down, in a counterintuitive fashion, it allows certain connections to form from the speech brain areas to the areas that control the vocal organ.

So we call it... A loss of function of the gene causes a gain of function in the behavior.

- Wow.

- All right?

It allows a certain connection to form.

We can see this connection form in mice.

And these mice, too, are producing more complex sequences of vocalizations.

- Wow.

Wow.

- We have not yet seen or thoroughly tested: can these mice imitate sounds?

That's our next step.

But I do think we're gonna have to manipulate multiple genes to get imitation.

But that's also theoretically possible.

- Geez.

So do you have models that basically you can play with the various genes and predict the behavioral output?

- Yeah, we have computer algorithms that we developed that look at the regulation of these several hundred genes.

If we were to tweak one in one direction or tweak it in another direction, we can make predictions.

- Well, this takes us to a obvious direction.

Are we moving toward a future where we have talking pets?

(Erich laughs) Is that.. (laughs) - Yeah, someone asked me about that recently, another scientist, you know, thinking about: can we actually do that?

- Yeah.

Yeah.

- All right.

Yes.

- Eventually.

Not today, but- - Yeah, and do people wanna know what their pets are thinking?

- Oh, yeah.

- You see?

I do think once you have the ability to imitate sounds, you have this inner speech in your brain.

And I believe that the inner speech brain circuit is the same that's being used to produce the sounds.

And that is separate from the auditory circuit that's hearing that speech.

- All right, so I got to throw this in.

You say you believe?

- Yes.

- So does that mean that no one has stuck a brain in a scanner and saw what lights up when you're talking to yourself?

- That means, maybe it's my cautious scientific self, is that there's debate- - Yeah, I see.

- If your consciousness, your inner speech brain areas, are the same as what's used to speak the sounds- - Is the debate based on data?

- Yeah, debate's based on data.

- Okay.

- And I strongly favor, you know, the human fMRI studies that show that the brain regions that control speech production is the same brain regions that is being lit up when you're actually thinking in speech.

- Right, right.

- Yeah.

- [Hakeem] Yeah, yeah, yeah.

- And so you asked about our pet animals, right?

- [Hakeem] Right.

Yeah.

- The pet animals have the brain areas that hear speech, but not produce them.

- [Hakeem] Oh, that's right.

- So I do think if we can get our pet animals to speak through genetic manipulations, that will both allow them, you know, to say what they've been thinking in the hearing pathway, you know, but it'll even give them a great ability now to have inner speech- - Oh, interesting.

- What we call conscious speaking.

- So if you wanna know what your pets are thinking, by giving them this ability, you're giving them new thoughts.

- That's right.

- Yeah.

- That's right.

- So it's not like you're getting that same animal, it's basically a new animal now.

- That's a possibility.

- Yeah.

- That's a possibility.

That's right.

Yes.

- Yeah, yeah, yeah.

- Yes.

- Wow.

So let's talk about this, then.

If we could not speak and then we could speak, that pathway from not speaking to speaking, so you say it goes from song into speech, potentially.

So how do you imagine that playing out?

So if we're singing for mating purposes, for, you know, that's not the same as: "Go get some water," right?

So does it start out as: ♪ Go get some water ♪ You know?

(Erich and Hakeem laughing) - It's like: ♪ Look at me.

♪ - Right, right.

That's where it starts, right?

Look at that.

- Yeah.

♪ I'm healthy and sexy ♪ You know?

- Right.

But how does it switch over to: ♪ Clean your room ♪ Right?

- Right.

Yes, yes.

Yeah.

- Like, how do we imagine this?

'Cause again, when you think about things that happen evolutionarily, you think that there are some driver.

Either it's preventing something bad from happening or making something good happen, right?

- Yeah.

- So how does speech fit into there?

Because singing for reproduction is directly on the evolutionary pathway, it's reproduction.

- That's right.

That's right, yeah.

- Yeah, yeah, yeah.

But speech is different.

It's one of those things that might, I would imagine, give you a slight advantage- - Right, right.

- At the start.

- Yeah, yeah.

You're kind of asking the question: How do you go from, like, Jennifer Lopez and Ricky Martin to Einstein?

Right?

- I don't get that analogy.

What are we... (laughing) - Because you have these musicians- - Oh, right, right.

- Who are, like, you know, fantastic singers, who, you know, have, let's say, sex appeal, right?

- Right, right, right.

- Where that ancient ability to imitate sounds then gets translated into now communicating complex, abstract ideas like the theory of relativity.

- [Hakeem] Yeah.

- So that's the parallel I'm trying to bring out.

- [Hakeem] That's, yeah, brilliant.

- I hope those people can appreciate that.

- [Hakeem] Yeah, yeah.

- So I would say that what is selecting for this ability to imitate sounds and pass on this information or these sounds, culturally, from one generation to the next is... Mate attraction is a strong selective factor in biology.

That's survival of the species.

- Yeah.

- All right?

Or survival of an individual or a population of individuals.

And so anything that can help being selected as a mate is going to be strongly selected for.

And if imitation of sounds and increasing the variety of sounds you produce, you know, like, the more information you have, the more attractive you are.

- Right.

- Right?

- Yeah.

- And think about it, the more intelligent you seem, the more attractive you will be.

- Ain't that the truth?

- Yes.

(both laughing) - No, but it's real.

- Yeah.

Yeah.

- That's a real phenomenon.

- And so that's selecting this vocal learning, singing ability.

And then after that, just like the dancing itself, you start to use this new ability in new ways, like for communicating concepts, communicating information and passing that information culturally from one generation to the next.

- [Hakeem] Yeah, yeah.

- And it does have a flaw.

And the flaw of the cultural transmission of vocalizations, as you go further and further away in geographic distance, you start to get dialects, you start to get new languages, new songs, until you don't understand each other anymore.

- [Hakeem] That's right.

- This happens in all vocal learners.

- Oh.

- All right?

- Yeah.

All species of vocal learners?

- All species of vocal learners.

- Yeah.

- Yeah.

As they move away from their origin territory, their repertoire starts to change- - Right, right, right.

Interesting.

- Until they don't understand each other anymore.

- Wow.

Yeah.

So I read a book many years ago that basically said you don't learn language; language is an instinct.

- Mm-hmm.

Yeah.

That's a little exaggeration, okay?

All right?

(Hakeem laughing) And I've heard people say that.

- [Hakeem] Yeah.

- So we have an instinct, we have an innate ability to learn how to imitate sounds, but the actual sounds that we imitate, the actual words, the syntax, and the grammar is something that is learned- - Got it.

- And passed on culturally.

- Got it.

Got it.

So what are they trying, what are getting at by saying it's an instinct that- - There's a genetic component to learn how to imitate sounds.

- Okay.

- All right?

You need the genetic circuit, I mean, the genetic molecular pathway, the genes that I talked about earlier that are specialized in the up or down regulation, that is genetically controlled.

If you don't have that, you won't learn how to imitate sounds.

- [Hakeem] Got it.

- But the actual acoustic structure to the sounds like sit, (speaks in Spanish) that is learned, it's not instinctual.

- Got it.

Go it.

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Now back to the show.

(graphic whooshes) So we know what learning language is like or coming to speak is like in humans, right?

You mentioned there's the instinctual component that's in our genes, in our hardware, in our brains, but then we have to learn the actual vocalizations of our local language, the accent of our local culture.

So, do the other animals go through a similar process?

Do they have like, "Coochie coochie coo," baby talk, and then eventually they- - Yeah.

So another characteristic you find in all vocal learners is they go through a developmental period, after hatching or birth, that goes through these critical periods in which they learn how to imitate sounds.

In humans, we start out what we call babbling.

- [Hakeem] Right.

- And then we go through a phase where we have like, we call it, in songbirds, like, plastic song, where we're starting to imitate, but we don't do it as well.

And then when we become a full-blown adult, we crystallize onto a particular set of vocalizations that are part of our repertoire, that are full-blown imitations of what we hear.

- Interesting.

- So you don't see this in a dog or chimpanzee.

There are small modifications to their vocalizations over time, but not some big ones- - I see.

- That go, you know, through juvenile development to adulthood.

- Yeah.

They don't go from, "Ooh, ooh, ooh, ah, ah," to, "Hello, good day."

- No, no.

That's right.

That's right.

Yes, yes.

- Yeah.

It's more: "Ooh, ooh, ah, ah, ah."

- Right, that's right.

- Yeah, yeah, yeah.

So birds, though, they're very complex in their vocalizations.

- Yep.

- So does that mean that they... And also I would say the same thing with whales, right?

They're very complex.

- That's right.

That's right.

- So they would have these critical junctures?

- That's right, these critical junctures.

And they have to be exposed to your own species.

So, what's also characteristic of all vocal learners is that they're taken care of, they're born precocial, right, where the young have to be taken care of by the parents.

Whereas like chickens, they can start walking right away.

They grow up with parents for a short period of time and then they're independent.

All vocal learning species aren't independent until later in life.

- Interesting.

- And this is because you got to give them time to go through these critical periods and learn how to imitate the particular repertoire in which they're exposed to.

- So it seems like there actually is some sort of communication going on that's similar-ish to the language we have right?

- Right.

Mm-hmm.

- So, how close have we gotten to interpreting that?

And do we see a day where, say, for example, with AI, perhaps, we could actually, you know, if we have videos of what they're doing and recordings of what they're saying as they're doing it, could we somehow use the equivalent of machine learning techniques to actually understand what they're saying as they speak in their own way?

- Yeah.

So, I... Actually, we're working with a group of people to do just this.

- You're already doing that?

- Yeah.

We're going to start.

Yeah.

- Okay.

- We're collecting up sounds of a whole repertoire of a species, sets of vocalizations from different parts of the world where the species lives, and then try to use AI tools to try to infer: Is there a grammar to it?

Is there a fundamental syntax?

- Is that not limiting?

'Cause that's how we think of our speech.

Is it- - Yeah.

- Is that the right- - Well, I would say searching for patterns.

- Got it.

Okay, yeah.

- Searching for patterns.

- [Hakeem] Right, right, right.

- And in searching for those patterns, you know, we might find some principled rules that, you know, hopefully are unbiased.

- Right, right.

And do you have that metadata of the circumstances that these vocalizations match?

- Yeah.

Yeah, so it can be done with AI tools.

You need a lot of data.

That's the way AI tools work.

We have data from all over the world, from animals in the wild, animals in captivity.

- [Hakeem] Interesting.

- Yeah.

- Yeah, yeah, yeah.

So you got a lot of data.

You got- - We have a lot of data, yes, yes.

And we need to generate more data as well but... So the point being that we humans think that other animals aren't so smart because what they're saying doesn't make sense to us.

- [Hakeem] Right.

- But they could be communicating in ways that we just don't realize, that is more complex than what it seems like to the ear.

- Right, right.

Yeah.

- And there are some species that have, like, thousands of songs, right?

And there are some that just have one, right, that are learned.

And so people have avoided those species that sing thousands of different kinds of songs, or even parrots.

You know, some parrots have these warble-like song vocalizations that seem to go on endlessly, with various different combinations.

And so there's more complexity out there to the vocal learning animal world.

- Right.

So it sounds like we haven't really even gotten deep into the data that we could be examining.

- That's right.

Just think about hearing a totally foreign language to your perception one day.

- Right.

Yeah.

- Do you think you're gonna understand what's going on?

No.

- No.

- No.

- No.

Not at all.

And that's with my own species.

- That's right.

- Yeah.

- That's right.

So much less in other species.

So I just think we don't have the computational or other kind of tools yet to do this, but with AI, it's maybe coming close.

- Yeah, yeah, yeah.

So, you know how there's this recent study of the last universal common ancestor, where they were like, "Oh, okay.

It lived at this time.

It was anaerobic bacteria.

It already had an immune system."

Just by looking at what's common among various species, has there been a study where we look at vocal learning species or non-vocal learning species to identify, you know, when perhaps these vocal learning genes showed up in the animal genome?

- Yeah.

We have some preliminary data from already sequenced genomes to indicate, and in a family tree of species, like of birds, to indicate that vocal learning showed up somewhere around 30 million years ago in songbirds and about 50 million years ago in parrots.

- [Hakeem] Oh, yeah.

- Because we sequenced different parrot species in... The kakapo from New Zealand, only 200 animals left on the planet, by the way.

- Oh boy.

- An endangered species of flightless parrots are at the base of the family tree of parrots.

- [Hakeem] Oh, interesting.

- And we find, in their genome, genetic changes we see in other parrot species that learn how to imitate sounds, not as advanced as the other parrot species, but still there.

But we don't find them in their closest relatives, who are the falcons, or what we call also, another group of, who are a non-vocal learning species.

- So you know when they split, and so you can- - We know when they split.

- Wow.

- Yeah.

- What about like in mammals?

Is there an earliest known case?

- Well, because we're finding some of these genetic changes in Neanderthals, you know, we're saying at least these genetic changes associated with speech went back 500,000 years ago.

- In humans?

- In humans.

- But in whales, it has to be- - In whales, I think it's gonna be in the 50 million-year range.

- Wow.

- Yeah.

- And these are all convergent evolution- - These are all, yeah.

All convergent.

And what's interesting is that all these vocal learning species evolved after the last mass extinction.

- Oh, interesting.

- Yeah.

- Okay.

- So I think there's something that, after the last mass extinction, 65 million years ago, there's something, ecological niches that opened up that influenced greater diversity and speciation that may have selected for vocal learning.

And we humans are just the last ones on the planet to evolve vocal learning.

- We're always late, man.

- Yes.

- You know, when they divide the earth into 24 hours, you know, we show up at the very end, right?

- And take credit for everything.

(both laugh) - Well, we're different, you know?

We're different.

- Yes.

That's right.

- I guess that would be a great question, like: What is the newest species to evolve on earth?

Right?

- That's right.

Yes.

That's right.

- It ain't us.

But that's the other question I have, right?

If you look at birds, they're super ancient.

- [Erich] Mm-hmm.

- If you look at humans, we've been rapidly evolving for, you know, a few million years.

Take Homo Erectus, right, their brain size doubles.

And I guess the question I have is: that brain size doubling, could language be a driver of that or a result of that?

- Yeah.

So just to make this comparison more equal.

So birds are part of an order that is pretty old, you know, 100, 150 million or more years ago, right, are the first birds.

Primates, to which humans belong, is the equivalent order, we would call it.

Primates are more recent, all right?, roughly around the time of the last mass extinction, so 60 million years.

So birds been on this planet two times more as primates.

- Twice as long, yeah.

Yeah.

- And then amongst the primates, we vocal learning primates, us humans, is let's say... I said somewhere around 500,000 to 1 million years ago.

That's when we evolved this ability, I believe.

But birds, you know, at least amongst songbirds, it's 30 million years ago, so times as long.

- Wow.

- Yeah.

So your question was?

(both laugh) Before I get lost on that sidetrack.

- It led to some good stuff, whatever it was.

- Well, I guess the question I had is, in the one case, you know, I don't know how much birds have changed over the time period- - I remember now.

- That they have been birds, right?

- Yes.

- But humans have been rapidly evolving.

- That's right.

- And one of the things that happened during Homo Erectus, which preceded this, all of us Homo cousins popping out, was their brain size doubled over this short period of time.

So I'm wondering if language was a driver of that or a result of that.

- I think so.

- Okay.

- I think so.

And here is, you know, my explanation for it, is that we humans do have a larger brain size relative to body size than other, not only primates, than other mammals.

And why is that the case?

Some people argue, well, it's because of greater intelligence, you need more brain to have greater intelligence, and so forth.

I do think that the speech brain circuits take up space, all right?

And they evolved out of this motor learning circuit that controls movement.

I don't think we lost brain tissue because of this new brain circuit, we just added to it and increased our skull size a little bit more.

It's not the only thing that I think is taking up greater space.

I do think there are parts of the human brain that take up more space, but the speech circuit, I think, is the biggest.

- Right, right.

And I would imagine that if it turns out to be evolutionarily advantageous, then it would continue along that path and perhaps get bigger and bigger.

I don't- - I think so.

Yeah.

But there's only so much size that your body can accommodate, you know, for a heavy head, all right?

The bigger the brain, the bigger the skull, the more skull you gotta carry around.

- Well, now that we're all bending over and, you know, how the- - Yes.

- They say that that makes your neck have to support more.

Our brains have to shrink now to accommodate- - That's right.

That's right.

- Our smartphones.

- So your head doesn't fall down too much.

(Hakeem laughing) Now, that's humans, okay.

What about birds?

Well, it turns out a colleague of mine, Herculano, from Brazil, she found that the brains of vocal learning birds, like songbirds and parrots, are not only bigger relative to body size like humans, but the difference in body size to brain size is not as big as humans.

How did they compensate for that?

They have a doubling of neurons.

They fit more neurons into a smaller brain space by increasing the density.

- So they have a more dense brain.

- They have a more dense brain.

- Wow.

- More dense than humans.

- Wow.

- More dense than other birds, you know?

So the total number of neurons in a parrot brain is the same as a monkey five times its brain size.

- Why are you guys keeping all this stuff secret?

This is so cool.

(laughs) I'm like, "How am I hearing all of this for the first time today?"

- Yep, yep.

- This is so amazing.

- Yeah, you get some cool stuff out of these birds.

That's why it keeps me going in studying them.

So I do think that this has allowed parrots and songbirds to now have this new vocal learning system, which I can physically see with my own eyes, when I look at those brain areas, take up a lot of space in the brain.

- Wow.

- Yeah.

- Yeah.

And is that the same thing with the whales?

Do they also have... Do they have denser brains?

I know they have big brains.

I know the sperm whale has the biggest brain on the planet.

- That's right.

- Yeah, yeah.

- That's right.

And they have big brains because they have big bodies too, you know?

- Right.

Yeah, yeah.

- But they do have large brains relative body size.

But- - But are they extra?

- We don't know that answer yet.

I have somebody in my lab trying to figure that out.

- So I guess you need a comparison.

Are there non-vocal learner whales that exist?

I just assume they're all- - No, we... So far, they look like they're all vocal learners.

There are some that have, producing more simple vocalizations, some producing more complex.

But when you look at them and study them, you know, purposely for this trait, you find that they're vocal learners.

- All right, so this is off the beaten path, but on the path.

We're talking vocal learning, but we humans use symbolic learning, or writing, right?

We use writing as well.

- Yep That's right.

- So is there anything similar to that?

And is there... The brain circuitry that allows for that, is that built... It has to be built off of something that was doing something else or pre-existing.

And so the question would be, the questions: Do we see that in any other species?

And do we see the circuitry for that in any other species?

- Yeah.

I'm glad you asked about the circuitry because I don't like to give answers to fancy or advanced behaviors unless I know there's an underlying biological explanation in the brain; otherwise, we could be making things up.

So far, there isn't any evidence that other species can write in the way humans do.

They can draw... Well, let's say a non-vocal learning species.

You can get chimps and other primates to push buttons on a screen to spell out something, but the actual writing with the hand and so forth, no.

And so I do think that is a unique human characteristic that did come about as a result of having spoken language.

What's going on there in the brain?

Based upon... Now, this is not work we did, but this is work that I pulled together from the literature.

- Well, let me broaden it a little bit, right?

Because there is that, some group that use knots as a written language, right?

And so you see that birds make these very complex structures- - Yep, like bowerbirds.

- Yeah.

- That's right.

- So it seems like, even if it's not writing with your hand, there are other ways to convey language symbolically.

- Yes.

Yes.

- Right.

- That's right.

That's right.

And I think some symbolic communication, like sign gesturing- - Yeah.

- Is more doable and doesn't require a speech pathway to do it.

- Right.

- All right?

So Coco, who was a gorilla, raised with humans for, like, 39 years, was able to learn how to produce signed communication in English, all right, for hundreds of words, some say thousands, all right?

Whereas she was not able to speak a single word.

She can cough, she can voluntarily blow air through the vocal tract, but not say a single word that she could sign.

- [Hakeem] Wow.

- So that ability to communicate symbolically is already there before speech evolves.

- Ah, yeah.

- And speech is an expression of a symbolic communication ability that we already had.

- Ah.

Wow.

Because even though writing came after speaking, so you think it's more complex.

But really, what you're saying, it's the opposite.

- That's right.

- Yeah.

- That's right.

And even the ability to give abstract information to sound came before vocal learning evolved, or let's say spoken language.

And vervet monkeys have been shown, for example, to produce alarm calls of various sorts that culturally get transmitted as information.

This alarm call means a snake on the ground.

This alarm call means an eagle in the sky, right?

So flee to the trees when you hear the snake alarm call, flee out of the trees or to some cover when you see, you know- - They have that level of specificity in their- - That's right.

- Wow.

- That's right.

And so this is abstract meaning to sounds.

I'm not saying it's a whole repertoire of hundreds of sounds that humans have, but that ability, at least, exists before spoken language evolved.

And now, back to writing, what I do think is going on is when we read, all right, we're sub-vocalizing the words on the page.

All right?

What I think is going on there is your eyes are seeing the words on the page, like on this cup, NOVA, right?

- Yeah, yeah, yeah.

Just like the gene you study, right?

The NOVA1 gene.

- That's right.

The NOVA1 gene.

That's right.

Yes, that's right.

(Erich and Hakeem laugh) And we're seeing this word here.

It's going through our eyes to the back of our brain, where our visual system is at.

From the back of the brain, that visual signal is sent, I believe, to our speech brain areas.

We speak it in our brain, the word NOVA, and then we hear it in our auditory system.

- Yeah, yeah.

- And that's how we read.

- Wow.

- We're speaking to ourselves when we read.

And you can even see a person sub-vocalizing their lips and their larynx without making a sound.

Some talk to themselves when they read too.

- Yeah, yeah, yeah.

Hey, so I'll tell you, man, I don't... You know, when I'm reading scientific papers, they're tough, right?

- Yep.

- So I've been in the airports, when I can't understand something, I start reading it out loud.

And, you know, I'm in there in the airport going, "Okay, so," and I read out a statement.

And people kind of look at me, right?

But what's happening in my brain?

Why is it that I have to say it out loud?

Or another thing.

If I'm driving through a neighborhood and I'm trying to, like, find something, I feel the need to turn down the radio.

- Right.

Mm-hmm.

- Right?

What's going on with this brain-thought connection, the sound connection?

- Because I do think we read through speaking.

And this is another, you know, evolutionary pre-adaptation, is our ability to translate sounds into meaning, or symbols into sounds, I should say.

- Right, right, right, right.

Yeah, yeah.

- And that, I think, is what's going on in the brain.

And us speaking it helps us understand what we're reading better.

If you try purposely not to speak, not to think in speech, you're gonna have a very difficult time reading.

- You know, I would put it in my syllabus, in my physics class.

You know, so after I get with all the logistical type stuff, I have these wise words, right?

And it reminds me of something I saw in one of your interviews, where you say, "Hey, where's Erich?

In the lab."

Right?

Right?

So two things I'm gonna tell you.

The first one that's similar to that.

I would put in there, I was like, "Yeah, you need to think physics all the time.

From now on, stop, at any point in your life, and say, 'I bet Dr.

O is thinking physics right now,' and you'd be correct.

And it will be correct of all my colleagues as well," right?

But the other thing I would put in there, I was like, "Listen, in order to understand physics, you need to speak it.

Reading it, doing problems about yourself is not going to make it happen for you.

You need to speak it."

And what, my colleagues, we've all admitted to each other is, oh, you know, I got my undergraduate degree, I thought I knew physics.

I go into graduate school, I went through the process of studying for the qualifying exam, which tests you on all of physics, and I thought I knew physics.

- Right.

- I graduated, got my PhD, made this discovery, I thought I knew physics.

But then when I started teaching the courses, that's when I really learned the physics, because there was something about me telling everyone else that took it to a level, like, was unreachable otherwise.

- Yeah.

Yep.

- What is going on there?

- Well, this suggests, and there's some studies out that show that, yeah, speaking things helps you understand them.

- Yeah.

- So there, that's another correlation.

That ability to speak helps us become more cognitively advanced.

I think I mentioned earlier that amongst songbird species, we did a study recently.

Nick Odette, in my lab, found that the more advanced vocal learning ability a songbird species has, the better they are at problem solving.

- [Hakeem] Oh, right.

- And guess what?

The more their brain size is bigger relative to their body.

So I think this ability to communicate through vocalizations, learn vocalizations, is selecting upon more advanced cognitive abilities, selecting for it.

- It drives it?

- It drives it.

It drives it.

- Yeah.

Yeah.

- Yes.

And that's why speaking, you know, your physics lessons, talking it out helps you learn it better.

- Yeah.

So I wonder where language fits in.

So when I look at, like, the big things that separated humans from the animals, right, for me, the first one is, it's not those stone tools because, you know, there's other animals that make one-step tools, right, it was the domestication of fire.

And then I look and I see agriculture, right, changes everything.

Where does language fall in there?

Is it as big of a changer for humanity?

- I think language... And when you say language, we gotta break that down, right, because there's spoken language, there is sign language- - Yeah, and there's singing.

- There's singing, right?

That's right.

There's dance communication, all those kinds.

So let's keep it to the spoken part, which is really the more specialized one and the more advanced ability in us humans and in these other species that imitate sounds.

It's not the case that all vocal learning species now have complex societies out there and agriculture.

You know, We don't see parrots or songbirds doing agriculture or inventing fire and tool... Tool use, yes.

- [Hakeem] Right, right, right.

- There might be some kind of correlation there, but you don't need to be a vocal learner, also, to learn how to use tools.

So what is common amongst all these species is they have more advanced social structures, more advanced societies, let's call it that, more advanced ways of communicating, and that's a commonality.

And once you put all this whole package together, then I think you start to evolve these other things like fire or inventing agriculture.

- Right, right, 'cause you get that population density because you have that social structure.

- That's right.

That's right.

So I think it's the sociality that comes first.

After, you know... It's the first, let's say, new thing that comes after the vocal imitation, evolution of the vocal behavior.

- You're able to build bigger, larger, more cohesive societies.

You're able to create stories around which- - That's right.

- Yeah.

Man!

- That's right, yeah.

- Let's do this every day.

(both laugh) This is like, yeah, it's like, it's a lot of questions I had that I didn't know I had, and now they're like.. You know, you're building this new structure, this new edifice for understanding the evolution of life and the evolution of my own species.

This is pretty amazing, man.

- Yeah.

To me, it's an exciting time to be a scientist in this area.

- It is.

It is.

- Yeah.

- I often feel like it's a cruel joke, life.

You know, we're given 100 years and you're born with a curiosity, and there's so much to know about the universe, but you're gonna run out of time.

You're never gonna get it all, and I want it all, you know?

- That's right, yeah.

- Yeah, yeah.

I wanna know everything.

- Yep.

Yep.

- And I'll tell you, speaking of cognitive science, I was reading a book many years ago, I think the year was around 2004, around years ago.

And this cognitive scientist was arguing that even things that we think are objective and independent of humanity, like math, are really still human creations, and in a way, our descriptors all go back to our five senses, our five major senses in some way.

Which the conclusion this particular person was, you know, what they were presenting was because there are thoughts you can never think, there is knowledge you can never know.

- Mm-hmm.

Yeah.

That's an interesting, you know, statement.

Yeah, if you don't think it, will you know it?

- And if you can't vocalize it, can you think it?

- I think it's possible to think without vocalizing because I imagine this is what other animals are doing.

We're just so used to doing it, you know, thinking in speech, that we can't imagine what it's like not to think in speech.

- Yeah, yeah.

Speech or math.

Right?

- Yeah, that's right.

Yep.

That's right.

Yes.

So I do think there are concepts, or even just seeing in different dimensions, we can't, you know, beyond a certain number.

And so, you know, we can only translate it, you know, to... I think of like hearing mouse ultrasonic vocalizations.

They produce ultrasonic vocalizations in a range we can't hear, and the only way we can hear it is if we pitch it down to our human hearing range.

- [Hakeem] Right.

Right.

- So the only way to understand concepts that our brains can't perceive, we have to find out that such a thing exists, and then, through technology, pitch it down.

- Yeah, transform it into a form we can- - Into a form that we can.

- Yeah.

Wow.

Man, this has been such a surprising interview.

- Oh, thank you.

- I learned so much that, you know, I didn't even know I didn't know, right?

But it's all amazingly fascinating work, man.

So, you have any books?

Do you have... If people wanna learn more about you, where do you suggest they go?

- Well, I do have some review papers that are written for the general public- - Oh, nice.

- Both on my science, the 2009 paper we published in "Science Magazine," as well as my career, my life- - Oh, wonderful.

- And particularly life as an underrepresented minority as well.

And one published in "Molecular Biology of the Cell" in 2015.

And for a book, that's happening now.

We're working on it.

- Wonderful.

Wonderful.

- Yes.

- Yeah, congratulations.

- Thank you.

- I know it's a lot of hard work, man, too.

- Yep, that's right.

- Yeah, yeah, yeah.

- That's right, because you wrote several books yourself.

- Yeah, yeah.

I know it... Yeah.

I'm just like, "This is tough."

- Right.

Yes.

- But writing a book is a research project, right?

- That's right.

- When I wanna learn a new topic, I find a leader like yourself, and it was like, "Hey, you know, let's talk," and we find a project.

And it typically takes around months to two years to get that project done.

And then, you know, you're now an expert in the field, at least on that one topic, right?

- That's right.

Yep.

- So now I could consider getting some grant money.

So, you know, now I wanna go study birds, darn it.

- Well, I'm glad you're so motivated.

(laughs) - No, man.

I find, I've always been interested with the brain since a very young child and the fact that you can understand more about... The fact that we're looking at life together as a system, and brain evolution, and the genetic evolution of the hardware, and the circuitry, you know, that's just beautiful to me.

That is- - Yeah.

- I love what... You know, your species was once eating fruit in trees in the carboniferous era, right?

And now you're... (laughs) - That's right, yes.

- Now you're getting the genome of every vertebrate.

- That's right.

- That is amazing.

- That's right.

- Yeah.

Thank you so much for joining, man.

- You're welcome.

You're welcome.

- Come back anytime.

- Thank you for inviting me.

This has been wonderful.

- This has been excellent.

- Yeah.

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