Dr. Erich Jarvis: The Neuroscience of Speech, Language & Music | Huberman Lab Podcast #87

- Welcome to the Huberman Lab Podcast,

where we discuss science and science-based tools

for everyday life.

[lively music]

I'm Andrew Huberman,

and I'm a professor of neurobiology and ophthalmology

at Stanford School of Medicine.

Today, my guest is Dr. Erich Jarvis.

Dr. Jarvis is a professor at the Rockefeller University

in New York City

and his laboratory studies,

the neurobiology of vocal learning, language,

speech disorders,

and remarkably, the relationship between language,

music and movement, in particular dance.

His work spans from genomics,

so the very genes that make up our genome

and the genomes of other species

that speak and have language

such as songbirds and parrots

all the way up to neural circuits,

that is the connections in the brain and body

that govern our ability to learn

and generate specific sounds

and movements coordinated with those sounds,

including hand movements

and all the way up to cognition,

that is our ability to think in specific ways,

based on what we are saying

and the way that we comprehend

what other people are saying, singing and doing.

As you'll soon see,

I was immediately transfixed

and absolutely enchanted by Dr. Jarvis's description

of his work and the ways that it impacts

all the various aspects of our lives.

For instance, I learned from Dr. Jarvis that as we read,

we are generating very low-levels

of motor activity in our throat.

That is, we are speaking the words that we are reading

at a level below the perception of sound

or our own perception of those words.

But if one were to put an amplifier

or to measure the firing of those muscles

in our vocal chords,

we'd find that as we're reading information,

we are actually speaking that information.

And as I learned, and you'll soon learn,

there's a direct link between those species

in the world that have song and movement,

which many of us would associate with dance

and our ability to learn and generate complex language.

So for people with speech disorders like stutter,

or for people who are interested

in multiple language learning,

bilingual, trilingual, et cetera,

and frankly for anyone who is interested

in how we communicate through words, written or spoken,

I'm certain today's episode is going to be

an especially interesting and important one for you.

Dr. Jarvis's work is so pioneering

that he has been awarded truly countless awards.

I'm not going to take our time to list off

all the various important awards that he's received,

but I should point out

that in addition to being a decorated professor

at the Rockefeller University,

he is also an investigator

with the Howard Hughes Medical Institute,

the so-called HHMI.

And for those of you that don't know,

HHMI investigators are selected

on an extremely competitive basis

that they have to re-up,

that is they have to recompete every five years.

They actually receive a grade every five years

that dictates whether or not they are no longer

a Howard Hughes investigator

or whether or not they can advance to another five years

of funding for their important research.

And indeed, Howard Hughes investigators

are selected not just for the rigor of their work,

but for their pioneering spirit

and their ability to take on high-risk, high-benefit work,

which is exactly the kind of work

that Dr. Jarvis has been providing for decades now.

Again, I think today's episode is one of the more unique

and special episodes that we've had

on the Huberman Lab Podcast.

I single it out because it really spans

from the basic to the applied

and Dr. Jarvis's story is an especially unique one

in terms of how he arrived at becoming a neurobiologist.

So for those of you that are interested

in personal journey and personal story,

Dr. Jarvis's is truly a special and important one.

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And now, for my discussion with Dr. Erich Jarvis.

Erich, it's so great to have you here.

- Thank you. - Yeah.

Very interested in learning from you

about speech and language.

And even as I ask the question,

I realize that a lot of people, including myself,

probably don't fully appreciate the distinction

between speech and language, right?

Speech, I think of as the motor patterns,

the production of sound

that has meaning, hopefully.

And language, of course, comes in various languages

and varieties of ways of communicating.

But in terms of the study of speech and language,

and thinking about how the brain

organizes speech and language,

what are the similarities?

What are the differences?

How should we think about speech and language?

- Yeah, well, I'm glad you, you know, inviting me here.

And I'm also glad to get that first question,

which I consider a provocative one.

The reason why, I've been struggling,

what is the difference with speech and language

for many years.

And realize, why am I struggling,

is because there are behavioral terms,

let's call 'em psychologically,

psychology developed kind of terms

that don't actually align exactly with brain function.

All right.

And the question is there a distinction

between speech and language?

And when I look at the brain

of work that other people have done, work we have done,

also compared it with animal models,

like those who can imitate sounds

like parrots and songbirds.

I start to see there really isn't such a sharp distinction.

So, to get at what I think is going on,

let me tell you how some people think of it now.

That there's a separate language module in the brain

that has all the algorithms and computations

that influence the speech pathway

on how to produce sound

and the auditory pathway on how to perceive

and interpret it for speech

or for, you know, sound that we call speech.

And it turns out,

I don't think there is any good evidence

for a separate language module.

Instead, there is a speech production pathway

that's controlling our larynx,

controlling our jaw muscles

that has built within it

all the complex algorithms for spoken language.

And there's the auditory pathway

that has built within it,

all the complex algorithms for understanding speech,

not separate from a language module.

And this speech production pathway

is specialized to humans

and parrots and songbirds,

whereas this auditory perception pathway

is more ubiquitous amongst the animal kingdom.

And this is why dogs can understand,

"sit", "sientese", "come here, boy",

"get the ball" and so forth.

Dogs can understand several hundred human speech words.

Great apes, you can teach them for several thousand,

but they can't say a word.

- Fascinating.

Because you've raised a number of animal species

early on here and because I have a,

basically an obsession with animals

since the time I was very small,

I have to ask, which animals have language?

Which animals have modes of communication

that are sort of like language.

- [Erich] Yeah.

- You know, I've heard whale songs.

I don't know what they're saying.

They sound very beautiful,

but they could be insulting each other for all I know.

- [Erich] Yeah.

- And they very well may be.

Dolphins, birds, I mean,

what do we understand about modes of communication

that are like language,

but might not be what would classically be called language?

- Yes, right.

So, modes of communication

that people would define as language,

more, very, in a very narrow definition,

they would say, production of sound, so speech.

But what about the hands, the gesturing with the hands?

What about a bird who is doing aerial displays in the air,

communicating information through body language, right.

Well, I'm going to go back to the brain.

So what I think is going on

is for spoken language,

we're using the speech pathway

and all the complex algorithms there.

Next to the brain regions

that are controlling spoken language

are the brain regions for gesturing with the hands.

And that hand parallel pathway

has also complex algorithms that we can utilize.

And some species are more advanced in these circuits,

whether it's sound or gesturing with hands

and some are less advanced.

Now, we, humans and a few others

are the most advanced for the speech sounds

or the spoken language,

but a non-human primate can produce gesturing

in a more advanced form than they could produce sound.

I'm not sure I got that across clearly,

just to say that humans are the most advanced

at spoken language,

but not necessarily as big a difference at gestural language

compared to some of the species.

- Very clear and very interesting.

And immediately prompts the question,

have there been brain imaging

or other sorts of studies evaluating neural activity

in the context of, you know, cultures and languages,

at least that I associate with a lot of hand movement,

like Italian. - Yep.

- Versus, I don't know,

maybe you could give us some examples of cultures

where language is not associated with

as much overt hand movement.

- Yes, so as you and I are talking here today

and people who are listening, but can't see us,

we're actually gesturing with our hands as we talk

without knowing it or doing it unconsciously.

And if we were talking on a telephone,

I would have one hand here

and I'd be gesturing with the other hand.

[Andrew laughs]

Without even you seeing me, right?

And so why is that?

Some have argued and I would agree,

but based upon what we've seen

is that there's an evolutionary relationship

between the brain pathways

that control speech production and gesturing.

And the brain regions I mentioned

are directly adjacent to each other.

And why is that?

I think that the brain pathways that control speech

evolved out of the brain pathways that control body movement.

All right.

And that

when you talk about Italian, French,

English, and so forth,

each one of those languages

come with a learned set of gestures

that you can communicate with.

Now, how is that related to other animals?

Well, Cocoa, a gorilla who is raised

with humans for 39 years or more,

learned how to do gesture communication,

learned how to sign language, so to speak, right?

But Cocoa couldn't produce those sounds.

Cocoa could understand them as well

by seeing somebody sign

or hearing somebody produce speech,

but Cocoa couldn't produce it with her voice.

And so, what's going on there is that

a number of species, not all of them,

a number of species have motor pathways in the brain

where you can do learn gesturing,

rudimentary language, if you wanted, say with your limbs,

even if it's not as advanced as humans.

But they don't have this extra brain pathway for the sound.

So they can't gesture with their voice

in the way that they gesture with their hands.

- I see.

One thing that I've wondered about for a very long time

is whether or not

primitive emotions and primitive sounds

are the early substrate of language.

And whether or not there's a bridge

that we can draw between those

in terms of just the basic respiration systems

associated with different extreme feelings.

Here's the way I'm imagining this might work.

When I smell something delicious,

I typically inhale more. - Hmm hmm.

- And I might say, mmm, or something like that.

Whereas if I smell something putrid,

I typically turn away, and I wince

and I will exhale [exhales],

you know or sort of kind of like turn away,

trying to not ingest those molecules

or inhale those molecules.

I could imagine that these

are the basic dark and light contrasts

of the language system.

And as I say that,

I'm saying that from the orientation of a vision scientist

who thinks of all visual images built up

in a very basic way of a hierarchical map model

of the ability to see dark and light.

So I could imagine this kind of primitive

to more sophisticated pyramid

of sound to language.

Is this a crazy idea?

Do we have any evidence this is the way it works?

- No, it's not a crazy idea.

And in fact,

you hit upon one of the key distinctions

in the field of research that I started out in,

which is vocal learning research.

So for vocal communication,

you have most vertebrate species vocalize,

but most of them are producing innate sounds

that they're born with producing,

that is babies crying, for example,

or dogs barking.

And only a few species have learned vocal communication,

the ability to imitate sounds.

And that is what makes spoken language special.

When people think of what's special about language,

it's the learned vocalizations.

That is what's rare.

And so, this distinction between innateness and learned

is more of a bigger dichotomy

when it comes to vocalizations

than for other behaviors in the animal kingdom.

And when you go in the brain,

you see it there as well.

And so all the things you talked about,

the breathing, the grunting and so forth,

a lot of that is handled by the brain stem circuits,

you know, right around the level of your neck and below.

Like a reflex kind of thing.

So, or even some emotional aspects of your behavior

in the hypothalamus and so forth.

But for a learned behavior,

learning how to speak,

learning how to play the piano,

teaching a dog to learn how to do tricks

is using the forebrain circuits.

And what has happened is

that there's a lot of forebrain circuits

that are controlling,

learning how to move body parts in these species,

but not for the vocalizations.

But in humans and in parrots and in some other species,

somehow, we acquired circuits

where the forebrain has taken over the brain stem

and now using that brain stem,

not only to produce the innate behaviors or vocal behaviors,

but the learned ones as well.

- Do we have any sense

of when modern or sophisticated language evolved?

You know, thinking back to the species that we evolved from,

and even within Homo sapiens,

has there been an evolution of language?

Has there been a devolution of language? [laughs]

- Yeah.

Yeah, I would say,

and to be able to answer that question,

it does come with the caveat

that I think we humans overrate ourselves

compared to other species.

And so it makes even scientists go astray

in trying to hypothesize

when, you especially don't find fossil evidence

of language that easily

out there in terms of what happened in the past.

Amongst the primates, which we humans belong to,

we are the only ones that

have this advanced vocal learning ability.

Now, it was assumed that it was only Homo sapiens,

then you can go back in time now

based upon genomic data,

not only of us living humans,

but of the fossils that have been found

for Homo sapiens, of Neanderthals, of Denisovan individuals

and discover that our ancestor, our human ancestors,

supposedly hybridized with these other hominid species.

And it was assumed that these other hominid species

don't learn how to imitate sounds.

I don't know of any species today

that's a vocal learner that can have children

with a non-vocal learning species.

I don't see it.

Doesn't mean it didn't exist.

And when we look at the genetic data

from these ancestral hominids, that, you know,

where we can look at genes that are involved

in learned vocal communication,

they have the same sequence as we humans do

for genes that function in speech circuits.

So I think Neanderthals had spoken language.

I'm not going to say it's as advanced as what it is in humans.

I don't know.

But I think it's been there for at least

between 500,000 to a million years

that our ancestors had this ability

and that we've been coming more and more advanced with it

culturally and possibly genetically.

But I think it's evolved sometime

in the last 500,000 to a million years.

- Incredible.

Maybe we could talk a little bit more

about the overlap between brain circuits

that control language and speech

in humans and other animals.

I was weaned in the neuroscience era

where birdsong and the ability of birds

to learn their tooter song

was and still is a prominent field,

subfield of neuroscience.

And then of course,

neuroimaging of humans speaking and learning, et cetera,

and this notion of a critical period,

a time in which language is learned more easily

than it is later in life.

And the names of the different brain areas

were quite different.

If one opens the textbooks,

we hear Wernicke's and Broca's for the humans.

And you look at the birds of it,

I remember, you know.

- HVC. - Robustus, striatum.

Area X. - That's right.

That's right, yes. - Et cetera.

But for most of our listeners,

those names won't mean a whole lot,

but in terms of homologies

between areas in terms of function, what do we know?

And how similar or different are the brain areas

controlling speech and language

in say a songbird and a young human child?

- Yeah, so, going back to the 1950s

or even a little earlier,

and Peter Muller and others who got involved in neurotology,

the study of neurobiology of behavior

in a natural way, right.

You know, they start to find that behaviorally,

there are these species of birds

like songbirds and parrots,

and now we also know hummingbirds, just three of them

out of the 40-something bird groups out there on the planet,

orders, that they can imitate sounds like we do.

And so that was a similarity.

In other words, they had this kind of behavior

that's more similar to us than chimpanzees have with us

or than chickens have with them, right,

their closer relatives.

And then they discovered even more similarities,

these critical periods that if you remove a child,

you know, this unfortunately happens where a child is feral

and is not raised with human

and goes through their puberty phase of growth,

it becomes hard for them to learn a language as an adult.

So there's this critical period where you learn best.

And even later on, when you're in regular society,

it's hard to learn.

Well, the birds undergo these same thing.

And then it was discovered that if they become deaf,

we humans become deaf,

our speech starts to deteriorate

without any kind of therapy.

If a non-human primate or, you know,

or let's say a chicken becomes deaf,

their vocalizations don't deteriorate.

very little at least.

Well, this happens in the vocal learning birds.

So there were all these behavioral parallels

that came along with a package,

and then people looked into the brain.

Fernando Nottebohm, my former PhD advisor,

and began to discover the Area X you talked about,

the robust nucleus of the archipallium.

And these brain pathways were not found

in the species who couldn't imitate

so there was a parallel here.

And then jumping many years later, you know,

I started to dig down into these brain circuits

to discover that these brain circuits

had parallel functions with the brain circuits for humans,

even though they're by a different name,

like Broca's laryngeal motor cortex.

And most recently,

we discovered not only the actual circuitry

and the connectivity are similar,

but the underlying genes that are expressed

in these brain regions in a specialized way,

different from the rest of the brain,

are also similar between humans, and songbirds and parrots.

So all the way down to the genes.

And now we're finding the specific mutations

are also similar, not always identical, but similar,

which indicates remarkable convergence

for a so-called complex behavior

in species separated by 300 million years

from a common ancestor.

And not only that,

we are discovering that mutations in these genes

that cause speech deficits in humans, like in FOXP2,

if you put those same mutations

or similar type of deficits in these vocal learning birds,

you get similar deficits.

So convergence of the behavior

is associated with similar genetic disorders

of the behavior.

- Incredible.

I have to ask, do hummingbird sing, or do they hum?

- Hummingbirds hum with their wings

and sing with their syrinx.

- In a coordinated way?

- In a coordinated way.

There's some species of hummingbirds that actually will,

Doug Ashler showed this,

that will flap their wings

and create a slapping sound with their wings

that's in unison with their song

and you would not know it,

but it sounds like a particular syllable in their songs,

even though it's their wings

and their voice at the same time.

- Hummingbirds are clapping to their song?

- Clapping with their,

they're snapping their wings together

in unison with a song to make it like,

if I'm going ba, da, da, da [bangs], but, da [bangs]

and I banged on the table

except they make it almost sound like their voice

with their wings.

- Incredible. - Yes.

- I, I'm...

- And they got some of the smallest brains around.

- As the kids would say mind blown, right?

- Yes. Yes.

- Incredible. - Yes.

- Incredible, I love hummingbirds.

And I always feel like it's such a special thing

to get a moment to see one

because they move around so fast

and they fled away so fast in these ballistic trajectories.

- [Erich] Yep.

- That when you get to see one stationary for a moment,

or even just hovering there,

you feel like you're extracting so much

from their little microcosm of life,

but now I realize they're playing music essentially.

- Right, exactly.

And what's amazing about hummingbirds

and I'm going to say, vocal learning species in general,

is that for whatever reason,

they seem to evolve multiple complex traits.

You know, this idea that the evolving language,

spoken language in particular,

comes along with a set of specializations.

- Incredible. - Yeah.

- When I was coming up in neuroscience,

I learned that I think it was the work of Peter Muller

that young birds learn,

songbirds learned their tooter song and learn it quite well,

but that they could learn the song of another tooter.

In other words, they could learn a different,

and for the listeners, I'm doing air quotes here,

"a different language",

"a different bird song",

different than their own species song.

But never as well as they could learn

their own natural genetically linked song.

- Yes. - Genetically linked,

meaning that it would be like

me being raised in a different culture,

and that I would learn the other language,

but not as well as I would have learned English.

This is the idea. - Yes.

- Is that true? - That is true, yes.

And that's what I learned growing up as well.

And talked to Peter Muller himself about before he passed.

Yeah, he used to call it the innate predisposition to learn.

All right.

So which would be kind of the equivalent

in the linguistic community of universal grammar.

There is something genetically

influencing our vocal communication

on top of what we learned culturally.

And so there's this balance

between the genetic control of speech

or a song in these birds

and the learned cultural control.

And so, yes, if you were to take,

you know, I mean, in this case,

we actually tried this at Rockefeller later on.

Take a zebra finch and raise it with a canary,

it would sing a song

that was sort of like a hybrid in between.

We call it a can-inch, right?

[both laughing]

And vice versa for the canary,

because there's something different

about their vocal musculature

or the circuitry in the brain.

And with a zebra finch, even with a closely related species,

if you would take a zebra finch, a young animal,

and in one cage next to it placed its own species,

adult male, right.

And in the other cage placed a Bengalese finch next to it,

it would preferably learn the song

from its own species neighbor.

But if you remove its neighbor,

it would learn that Bengalese finch very well.

- [Andrew] Fantastic.

- It has something to do with also the social bonding

with your own species.

- Incredible.

That raises a question that I,

based on something I also heard,

but I don't have any scientific

peer-reviewed publication to point to,

which is this idea of Pidgin not the bird,

but this idea of when multiple cultures

and languages converge in a given geographic area,

that the children of all the different native languages

will come up with their own language.

I think this was in island culture,

maybe in Hawaii, called Pidgin,

which is sort of a hybrid of the various languages

that their parents speak at home

and that they themselves speak.

And that somehow Pidgin again, not the bird,

but a language called Pidgin,

for reasons, I don't know,

harbors certain basic elements of all language.

Is that true?

Is that not true?

- I would say, I haven't studied enough myself

in terms of Pidgin, specifically,

but in terms of cultural evolution of language

and hybridization between different cultures and so forth,

even amongst birds with different dialects

and you bring them together, you know,

what is going on here is cultural evolution

remarkably tracks genetic evolution.

So if you bring people

from two separate populations together

that have been in their separate populations,

evolutionarily, at least for hundreds of generations,

so someone's speaking Chinese,

someone's speaking English,

and that child is then learning from both of them.

Yes, that child's going to be able to pick up

and merge phonemes and words together

in a way that an adult wouldn't, because, why?

They're experiencing both languages at the same time

during their critical period years,

in a way that adults would not be able to experience.

And so you get a hybrid.

And the lowest common denominator

is going to be what they share.

And so the phonemes that they've re retained

in each of their languages is what's going to be,

I imagine, used the most.

- Interesting.

So we've got brain circuits in songbirds and in humans

that in many ways are similar,

perhaps not in their exact wiring,

but in their basic contour of wiring.

And genes that are expressed

in both sets of neural circuits in very distinct species

that are responsible for these phenomenon

we're calling speech and language.

What sorts of things are those genes controlling?

I could imagine they were controlling the wiring

of connections between brain areas.

You know, essentially a map of, you know, of a circuit,

basically like an engineer

would design a circuit for speech and language,

nature designed the circuit for speech and language,

but presumably other things too.

Like the ability to connect motor patterns

within the throat of muscles within the throat,

or in the control of the tongue.

I mean, what are these genes doing?

- You're pretty good, yeah.

You've made some very good guesses there that makes sense.

So, yes, one of the things that differ

in the speech pathways of us

and these song pathways of birds

is some of the connections are fundamentally different

than the surrounding circuits,

like a direct cortical connection

from the areas that control vocalizations in the cortex

or the motor neurons that control the larynx,

in humans or the syrinx in birds.

And so we actually made a prediction

that since some of these connections differ,

we're going to find genes that control neural connectivity,

and that specialize in that function, that differ.

And that's exactly what we found.

Genes that control what we call axon guidance

and form neuronal connections,

and what was interesting,

it was sort of in the opposite direction that we expected.

That is, some of these genes,

actually, a number of them

that control neural connectivity were turned off

in the speech circuit, all right.

And it didn't make sense to us at first

until we started to realize the function

of these genes are to repel connections from forming,

so repulsive molecules.

And so when you turn them off,

they allow certain connections to form

that normally would have not formed.

So by turning it off,

you gain a function for speech, right?

Other genes that surprised us

were genes involved in calcium buffering neuroprotection,

like Parvalbumin or heat-shock proteins,

so when your brain gets hot, these proteins turn on.

And we couldn't figure out for a long time,

why is that the case?

And then the idea popped to me one day and said, ah,

when I heard the larynx is the fastest firing muscles

in the body, all right.

In order to vibrate sound

and modulate sound in the way we do,

you have to control,

you have to move those muscles, you know,

three to four to five times faster

than just regular walking or running.

And so when you stick electrodes

in the brain areas that control learned vocalizations

in these birds and I think in humans as well,

those neurons are firing at a higher rate

to control these muscles.

And so what is that going to do?

You're going to have lots of toxicity in those neurons,

unless you upregulate molecules

that take out the extra load

that is needed to control the larynx.

And then finally, a third set of genes

that are specialized in these speech circuit

are involved in neuroplasticity.

Neuroplasticity, meaning allowing the brain circuits

to be more flexible so you can learn better.

And why is that?

I think learning how to produce speech

is a more complex learning ability

than say learning how to walk

or learning how to do tricks

and jumps and so forth that dogs do.

- Yeah, it's interesting as you say that,

because I realize that many aspects of speech

are sort of reflexive.

I'm not thinking about each word I'm going to say,

they just sort of roll out of my mouth,

hopefully with some forethought.

We both know people that seem to speak, think less,

fewer synapses between their brain and their mouth

than others, right. - Yes.

- A lot of examples out there,

and some people are very deliberate in their speech,

but nonetheless, that much of speech has to be precise.

And some of it less precise.

In terms of plasticity of speech

and the ability to learn multiple languages,

but even just one language,

what's going on in the critical period,

the so-called critical period? - Yeah.

- Why is it that, so my niece speaks Spanish.

She's Guatemalan and speaks Spanish

and English incredibly well.

She's 14-years-old.

I've struggled with Spanish my whole life.

My father is bilingual.

My mother is not.

I've tried to learn Spanish as an adult.

It's really challenging.

I'm told that had I learned it when I was eight,

I would be better off. - That's right.

- Or it would be installed within me.

So the first question is,

is it easier to learn multiple languages

without an accent early in life?

And if so, why?

And then the second question is

if one can already speak more than one language

as a consequence of childhood learning,

is it easier to acquire new languages later on?

- So, the answer to both of those questions is yes, in that,

but to explain this, I need to let you know,

actually the entire brain

is undergoing a critical period development,

not just the speech pathways.

And so it's easier to learn how to play a piano.

It's easier to learn how to ride a bike

for the first time and so forth

as a young child than it is later in life.

What I mean easier in terms of when you start

from first principles of learning something.

So the very first time,

if you're going to learn Chinese as a child

versus the very first time you learn Chinese as an adult

or learning to play piano as a child versus an adult.

But the speech pathways,

or let's say speech behavior,

I think has a stronger critical period

change to it than other circuits.

And why, what's going on there in general?

Why do you need a critical period

to make you more stable,

to make you more stubborn, so to speak?

The reason I believe is that the brain is not for,

the brain can only hold so much information.

And if you are undergoing rapid learning to learn,

to acquire new knowledge,

you also have to, you know, dumb stuff.

Put in memory or information in the trash,

like in a computer.

You only have so many gigabases of memory.

And so therefore, plus also for survival,

you don't want to keep forgetting things.

And so the brain is designed, I believe,

to undergo this critical period

and solidify the circuits with what you learned as a child

and you use that for the rest of your life.

And we humans stay even more plastic in our brain functions

controlled by a gene called srGAP2.

We have an extra copy of it

that leads our speech circuit and other brain regions

in a more immature state throughout life

compared to other animals.

So we're more immature.

We're still juvenile like compared to other animals.

- I knew it.

- But we still go through the critical periods

like they all do.

And now the question you asked about,

if you learn more languages as a child,

is it easier to learn as an adult?

And that's a common finding out there in the literature.

There's some that argue against it.

But for those that support it, the idea there is,

you are born with a set of innate sounds

you can produce of phonemes.

And you narrow that down

because not all languages use all of them.

And so you narrow down the ones

you use to string the phonemes together,

in words that you learn

and you maintain those phonemes as an adult.

And here comes along another language

that's using those phonemes

or in different combinations you're not used to.

And therefore, it's like starting from first principles,

but if you already have them

in multiple languages that you're using,

then it makes it easier to use them

in another third or fourth language.

- I see, incredible.

- So, it's not like your brain

has maintained greater plasticity,

it's your brain has maintained greater ability

to produce different sounds

that then allows you to learn another language faster.

- Got it.

Are the hand gestures associated with sounds

or with meanings of words?

- I think the hand gestures are associated

with both the sounds and the meaning.

When I say sound like if you are really angry, right,

and you are making a loud screaming noise, right,

you may make hand gestures

that look like you're going to beat the wall, right?

Because you're making loud sounds and loud gestures, right.

But if you want to explain something like, come over here,

what I just do now to you for those who can't see me,

I swung my hand towards you and swung it here to me.

That has a meaning to it, to come here.

So just like with the voice,

the hand gestures are producing both, you know,

both qualities of sound.

- And for people that speak multiple languages,

especially those that learn those multiple languages

early in development,

do they switch their patterns of motor movements

according to let's say,

going from Italian to Arabic

or from Arabic to French

in a way that matches the precision of language

that they're speaking?

- You know what?

You just asked me a question,

I don't know the answer to.

I would imagine that would make sense because of switching

in terms of sometimes people might call this code switching,

even different dialects of the same language.

Could you do that with your gestures?

I imagine so, but I really don't know if that's true or not.

- Okay, well, I certainly don't know from my own experience

because I only speak one language.

[both laughing]

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To go a little bit into the abstract, but not too far,

what about modes of speech and language

that seem to have a depth of emotionality and meaning,

but for which it departs from structured language.

Here's what I mean, poetry. - Hmm hmm.

- I think of musicians,

like there's some Bob Dylan songs that, to me,

I understand the individual words.

I like to think there's an emotion associated with it.

at least, I experience some sort of emotion

and I have a guess about what he was experiencing.

But if I were to just read it linearly without the music

and without him singing it, or somebody singing it like him,

it wouldn't hold any meaning.

So in other words, words that seem to have meaning,

but not associated with language,

but somehow tap into an emotionality.

- Yep, absolutely.

So, we call this difference semantic communication,

communication with meaning

and effective communication,

communication that has more

of an emotional feeling content to it,

you know, but not with, you know, the semantics.

And the two can be mixed up,

like with singing words that have meaning,

but also have this effect of emotional,

you just love the sound of the singer that you're hearing.

And initially, you know,

psychologists, scientists, in general,

thought that these were going to be controlled

by different brain circuits.

And it is the case.

There are emotional brain centers in the hypothalamus,

in the cingulate cortex and so forth,

that do give tone to the sounds.

But I believe, you know, based upon imaging work

and work we see in birds,

when birds are communicating semantic information

in their sounds, which is not too often, but it happens,

versus effective communication,

sing because I'm trying to attract the mate,

my courtship song or defend my territory,

it's the same brain circuits.

It's the same speech-like or song,

circuits are being used in different ways.

- A friend of mine, who's also a therapist, said to me,

you know, it's possible to say,

I love you with intense hatred

than to say, I hate you with intense love.

- [Eric] Right.

- And reminding me that it's possible to hear

both of those statements in either way.

So I guess it's not just limited to song or poetry.

It also, there's something about the intention

and the emotional context in which something spoken

that it can heavily shape the way

that we interpret what we hear.

- That's right.

And I consider all of that actually, meaning,

even though I defined it as,

people commonly do semantic and effective communication.

Effective communication to say, I hate you,

but meant love, right,

does have emotional meaning to it, you know?

And so, you know, one's more like an object kind of meaning

or an abstract kind of meaning.

There's several other points here

I think it's important for those listening out there to hear

is that when I say also

this effective and semantic communication

being used by similar brain circuits,

it also matters, the side of the brain.

In birds and in humans,

there's left-right dominance

for learned communication, learned sound communication.

So the left in us humans is more dominant for speech,

but the right has a more balance for singing

or processing musical sounds

as opposed to processing speech.

Both get used for both reasons.

And so when people say your right brain

is your artistic brain

and your left brain is your thinking brain,

this is what they're referring to.

And so that's another distinction.

A second thing that's useful to know

is that all vocal learning species

use their learned sounds for this emotional

effective kind of communication,

but only a few of them like humans

and some parrots and dolphins

use it for the semantic kind of communication,

we're calling speech.

And that has led a number of people to hypothesize

that the evolution of spoken language, of speech,

evolved first for singing,

for this more like emotional

kind of mate attraction like the Jennifer Lopez,

the Ricky Martin kind of songs and so forth.

And then later on,

it became used for abstract communication

like we're doing now.

- Oh, interesting.

Well, that's a perfect segue for me

to be able to ask you about your background

and motor control, not only of the hands but of the body.

So you have a number of important distinctions to your name,

but one of them is that you were a member

of the Alvin Ailey Dance School,

School of Dance. - That's right.

That's right, hmm hmm.

- So you're an accomplished

and quite able dancer, right?

Tell us a little bit about your background

in the world of dance

and how it informs your interest in neuroscience,

[clears throat], excuse me,

and perhaps even how it relates

specifically to your work on speech and language.

- Yes, well, it's interesting.

And then this kind of history even goes before my time.

So in my family, my mother and father's side,

they both went to the High School of Music and Art

here in New York City.

And particularly, in my mother's family,

going back multiple generations, they were singers.

And I even did my family genealogy

and found out not only, you know,

we have some relationships to some well-known singers,

distant relationships like Thelonious Monk,

but going back to the plantations

in North Carolina and so forth,

my ancestors were singers in the church

for the, you know, the towns and so forth.

And this somehow got passed on

multiple generations to my family.

And I thought I was going to grow up

and be a famous singer, right.

And me and my brothers and sister

formed a band when we were kids and so forth.

But it turned out that I didn't inherit

the singing talents of some of my other family members,

even though, you know, I was, you know, okay.

You know, but not like my brother,

or not like my mother or my aunts and my cousin Pura Fe',

who's now a talented Native American singer.

And so,

that then influenced me to do other things.

And I started, you know, competing in dance contests,

you know, actually this is around the time

of Saturday Night Fever and I was as a teenager.

And I started winning dance contests.

And I thought, oh, I can dance.

And I auditioned for the High School of Performing Arts.

And I got in, here in New York City,

and got into ballet dance and got in, right.

And thought, if I learned ballet,

I can learn everything else.

It I that idea, if you learn something classical,

it can teach for everything else.

And I was, yeah, at Alvin Ailey Dance School,

Joffrey Ballet Dance School.

And at the end of my senior concert,

I had this opportunity to audition

for the Alvin Ailey Dance Company.

And I had an opportunity to go to college.

And I also fell in love with another passion

that my father had, which was science.

And so I liked science in high school.

And I found an overlap also between the arts and sciences,

you know, both required creativity, hard work, discipline,

you know, new discovery, both weren't boring to me.

And the one decision I made at that senior dance concert

was, you know, when talking to the Alvin Ailey recruiter

and thinking about it,

I have to make a decision.

And I thought something my mother taught me

because she was growing up in the 1960s cultural revolution,

"Do something that has a positive impact on society."

And I thought that I could do that better

as a dancer than a scientist.

So now jump, I get into college, undergraduate school,

I major in molecular biology and mathematics.

I decide I want to be a biologist,

got into graduate school,

wanted to study the brain at, you know,

at the Rockefeller University.

So I went from Hunter College to Rockefeller University.

And so now I got to the brain

and why did I choose the brain

is because it controls dancing. [laughs]

But there wasn't anybody studying dancing.

And I wanted study the brain,

something that it does

that's really interesting and complex.

And I thought, ah, language is what it does.

You couldn't study that in mice.

You couldn't study in non-human primates.

But these birds do this wonderful thing

that Fernando Nottebohm was studying at Rockefeller.

And so that's what got me into the birds.

And then jumping now, 15 years later,

you know, yeah, that's right.

Even after I'm into now having my own lab,

studying vocal learning in these birds

as a model for language and humans,

it turns out that, you know,

Ani Patel and, you know, others,

have discovered that only vocal learning species

can learn how to dance.

- Is that right? - That's right, yes.

- So I've seen these just scrolling

through the files here in my mind.

I think about, every once in a while someone will,

I love parrots. - Yes.

- So every once in a while,

someone will send me one of these little Instagram

or Twitter videos of a parrot

doing what looks to me like dance,

typically it's a cockatoo. - That's right.

- Right. - That's right.

- Even foot stomping to the sound and-

- Famous one called Snowball out there,

but there are many Snowballs out there. [laughs]

- All the dancing birds are named Snowball?

That's an interesting tactic.

So only animals with language dance?

- Yeah, vocal learning in particular,

the ability to imitate sounds, yes.

- Incredible. - Yes.

And this now is bringing my life full circle, right.

And so when that was discovered in 2009,

at that same time in my lab at Duke,

we had discovered that vocal learning brain pathways

in songbirds, as well as in humans

and in parrots, right, like Snowball,

are embedded within circuits

that control learning how to move.

And that led us to a theory called the Brain Pathway

or Motor Theory of Vocal Learning Origin

where the brain pathways for vocal learning and speech

evolved by a whole duplication

of the surrounding motor circuits

involving learning how to move.

Now, how does that explain dance, right?

Well, when Snowball, the cockatoos, are dancing,

they're using the brain regions

around their speech-like circuits

to do this dancing behavior.

And so what's going on there?

What we hypothesize and now like to test

is that when this,

when speech evolved in humans

and the equivalent behavior and parrots and songbirds,

it required a very tight integration

in the brain regions that can hear sound

with the brain regions that control your muscles

from moving your larynx and tongue and so forth

for producing sound.

And that tight auditory motor integration,

we argue, then contaminated the surrounding brain regions.

And that contamination of the surrounding brain regions

now allows us humans, in particular, and parrots.

to coordinate our muscle movements of the rest of the body

with sound in the same way we do for speech sounds.

- [Andrew] Well.

- So we're speaking with our bodies when we dance.

- Incredible.

And I have to say that

as poor as I am at speaking multiple languages,

I'm even worse at dancing, so.

- But I guarantee you're better than a monkey.

- But not Snowball, the cockatoo?

- No, maybe not Snowball.

On YouTube, we have a video

where there's some scientists dancing with Snowball

and you'll see Snowballs doing better

than some of the scientists.

- Okay, well, as long as I'm not the worst

of all scientists dancing. - I don't think so.

- There's always a neuroplasticity.

May it save me someday.

You said something incredible

that I completely believe even though I have minimum to,

let's just say minimum dancing ability.

Okay, I can get by at a party or wedding

without complete embarrassment,

but I don't have any structured training.

So the body clearly can communicate with movement.

As a trained dancer and knowing other trained dancers,

I always think of dance and bodily movement

and communication through bodily movement

as a form of wordlessness,

like a state of wordlessness.

In fact, the few times when I think

that maybe I'm actually dancing modestly well

for the context that I'm in,

or I see other people dancing

and they seem to just be very much in the movement,

it's almost like a state of non-language,

non-spoken language. - Hmm hmm.

- And yet what you're telling me is

that there's a direct bridge at some level

between the movement of the body and language.

So is there a language of the body

that is distinct from the language of speech?

And if so, or if not, how do those map onto one another?

What does that Venn diagram look like?

- Yeah, yeah.

So, let me define first dance in this context

of vocal learning species.

This is the kind of dancing

that we are specialized in doing

and the vocal learning species are specialized in doing

is synchronizing body movements of muscles

to the rhythmic beats of music.

And for some reason, we like doing that.

We like synchronizing to sound

and doing it together as a group of people.

And that kind of communication amongst ourselves

is more like the effective kind of communication

I mentioned earlier,

unlike the semantic kind.

So we, humans, are using our voices more

for the semantic, abstract communication,

but we're using learned dance

for the effective emotional bonding kind of communication.

It doesn't mean we can't communicate semantic information

in dance, and we do it,

but it's not as popular.

You know, like a ballet that, you know, in the Nutcracker,

it is popular, you know,

where they are communicating,

you know, the Arabian guy comes out,

which I was the Arabian guy in the ballet Nutcracker.

That's how I remember. - Oh, yeah?

- Yeah, for the Westchester Ballet Company,

when I was a teenager.

You know, we're trying to communicate meaning

and our ballet dancing, it can go on

with a whole story and so forth.

But people don't interpret that as clearly as speech.

You know, they're seeing the ballet

with semantic communication,

with a lot of emotional content,

whereas you go out to a club, you know,

yeah, you're not communicating,

okay, how you're feeling today?

Tell me about your day and so forth.

You're trying to synchronize with other people

in an effective way.

And I think that's because,

the dance brain circuit

inherited the more ancient part of the speech circuit,

which was for singing.

- I always had the feeling

that with certain forms of music, in particular opera,

but any kind of music where there's some long notes sung

that at some level,

there was a literal resonance created

between the singer and the listener.

Or I think of like the deep voice of a Johnny Cash

or where at some level,

you can almost feel the voice in your own body.

And in theory, that could be the vibration of the

or the firing of the phrenic nerve

controlling the diaphragm for all I know.

Is there any evidence that there's a coordination

between performer and audience

at the level of mind and body?

- I'm going to say, possibly, yes.

And the reason why is

because I just came back from a conference

on the neurobiology of dance-

- Clearly, I'm going to the wrong meetings.

- Yeah, a colleague invited me.

- You know, vision science sounds be so boring.

- Yes, well, one of my colleagues,

Tecumseh Fitch and Jonathan Fritz,

they organized, well, a particular section

on this conference in Virginia.

And this is the first time I was in the room

with so many neuroscientists

studying the neurobiology of dance.

It's a new field now, in the last five years.

And there was one lab

where they were putting EEG electrodes on the dancers,

on two different dancers partnering with each other,

as well as the audience, you know, seeing the dance

and some, you know, argued,

okay, if you're listening to the music as well,

how are you responding

'cause you're asking a question about music

and I'm giving you an answer about dance.

And what they found is that, you know, the dancers,

when they resonated with each other during the dance,

or the audience listening to the dancers and the music,

there's some resonance going on there

that they've score as higher resonance.

Their brain activity with these wireless EEG signals

are showing something different.

And so that's why I say possibly, yes.

It needs more rigorous study

and you know, this is some stuff they publish,

but it's not prime time yet,

but they're trying to figure this out.

- Love it.

So at least if I can't dance well,

maybe I can hear and feel

what it is to dance in a certain way.

- Yes, that's right.

And this will be, some people will think that they,

even songs that they hear

and they can almost sing to themselves in their own head

and they know what they want it to sound like.

And you know when it really sounds good,

what it sounds like,

but they can't get their voice to do it.

- I'm raising, for those listening,

I'm raising my hand.

No musical ability.

Others in my household have tremendous musical ability

with instruments and with voice, but not me.

- Yeah, well, and so this is one of my selfish goals

of trying to find the genetics

of why can some people who sing really well and some not.

Is there some genetic predisposition to that?

And then can I modify my own muscles

of brain circuits to sing better?

- You're still after the sing.

I guess this is what happens

when siblings vary in proficiency

is that competitiveness amongst brothers

and sisters never goes away.

- I've been trying to be as good as my brother,

Mark and Victor, you know, for my entire life.

- Well, watch out, Mark and Victor,

he's coming for you with neuroscience to back him.

Earlier, you said that you discovered that you could dance.

That caught my ear.

It sounds like you didn't actually have to,

I'm not suggesting you didn't work hard at it.

But at the moment where you discovered it,

it just sort of was a skill that you had,

that up until that point,

you didn't target a life in the world of dance,

but the fact that you quote, unquote,

"discovered that you could dance really well"

and then went to this incredible school of dance

and did well,

tells me that perhaps there is an ability

that was built up in childhood

and or that perhaps we do all have

different genetic leanings for different motor functions.

- Yeah, well, for me, there could be,

both explanations could be possible.

For the first, yeah, I grew up in a family,

listening to Motown songs,

you know, dancing, you know, at parties and so forth,

family parties and, you know,

an African American family, basically.

And so I grew up dancing from a young child,

but this discovery, you know, maybe dancing even moreso,

in terms of a talent,

it could, the genetic component,

if it really exists, I don't know.

You know, with my 23andMe results, you know,

it says I have the genetic substitutions

that are associated with, you know,

high intensity athletes and fast twitch muscles.

And who knows.

Maybe that could have something to do with

me being able to synchronize my body

to rhythmic sounds, maybe,

maybe, better than some others.

It turns out that my genetics also show

that I have a genetic substitute

that makes it hard for me to sing on pitch.

And so that does correlate with my, you know,

even though I can sing on this pitch,

especially if I hear a piano or, you know,

kind of playing it, but,

you know, maybe that's why my siblings, you know,

who didn't have that genetic predisposition

in his 23andMe results, you know,

it could go along with the genetic component, as well.

- I'm imagining family gatherings with 23andMe data

and intense arguments about it,

innate and learned ability. - Yes.

- Fun.

Love to be an attendant.

I'm not inviting myself to your Thanksgiving dinner

by the way, but I suppose I am.

- You're welcome to. - Thank you.

I'll bring my 23andMe data.

I'd love to chat a moment about facial expression

because that's a form of motor pattern that,

you know, I think for most people out there

just think about smiling and frowning,

but there are, of course, you know, thousands,

if not millions of micro expressions

and things of that sort,

many of which are subconscious.

And we are all familiar with the fact that

when what somebody says

doesn't match some specific feature

of their facial expression

that it can call, you know,

that mismatch can cue our attention,

especially among people that know each other very well.

Like somebody will say, well, you said that,

but your right eye twitched to the, you know,

a little bit in a way that tells me

that you didn't really mean that,

these kinds of things.

Or when, in the opposite example,

when the emotionality and the content of our speech

is matched to a facial expression,

there's something that's just so wonderful about that,

because it seems like everything's aligned.

- [Erich] Yeah.

- So how does the motor circuitry

that controls facial expression

map onto the brain circuits that control language,

speech, and even bodily and hand movements?

- Yeah, and you ask a great question

because we both know some colleagues

like Winrich Freiwald at Rockefeller University

who study facial expression and the neurology behind it.

And now we both share some students that we're co-mentoring.

And talk about this same question that you brought up.

And what I'm learning a lot

is that non-human primates have a lot of diversity

in their facial expression like we humans do.

And what we know about the neurobiology

of brain regions controlling those muscles of the face

is that these non-human primates

and some other species that don't learn

how to imitate vocalizations,

they have strong connections from the cortical regions

to the motor neurons that control facial expressions,

but absent connections or weak connections

to the motor neurons that control the voice.

So I think our diverse facial expression,

even though it's more diverse in these non-human primates,

there was already a preexisting diversity of communication,

whether it's intentional or unconscious

through facial expression in our ancestors.

And on top of that, we humans now add the voice

along with those facial expressions.

- I see.

And in terms of language learning when we're kids,

I mean, children, fortunately are not told

to fake their expressions

or to smile when they say I'm happy.

So at some point, everybody learns, for better or for worse,

how to untangle these different components of hand movement,

body posture, speech, and facial expression.

- [Erich] Yes.

- But in their best form, I would say,

assuming that the best form is always,

I guess there are instances where, you know,

for safety reasons, one might need

to fain some of these aspects of language.

But in most cases, when those are aligned,

it seems like that could reflect that

all the different circuitries are operating in parallel,

but that the ability to misalign these

is also a powerful aspect to our maturation.

I can think of theater, for instance,

where deliberate disentangling of these areas is important.

But also we know when an actor,

when it feels real. - Yep.

- And when it looks like,

when bad acting is oftentimes

when the facial expression or body posture

just doesn't quite match what we're hearing.

- [Erich] Yeah.

- So are these skills that people,

that learn and acquire according

to adaptability and profession?

Or do you think that all children and all adults

eventually learn how to couple

and uncouple these circuits a little bit?

- Yeah, I think it's this similar argument

I mentioned earlier about the innate and learned

for the vocalizations.

And by the way, when I say,

we humans have facial expressions

associated with our vocalizations

in a different way than primates, non-human primates,

it's the learned vocalizations I'm talking about.

So there is a common view out there

that facial expressions in non-human species

like nonhuman primates,

or you can have them in birds, too,

are innate, all right.

And so they're reflexive and controlled.

I don't believe that.

I think there's some learned component to it.

And I think we have more learning component to it as well,

but we also have an innate component.

And so if you try to put your hands behind your back

and hold your fist, or even just not,

and try to speak and try to communicate,

it's actually harder to do.

You have to force yourself or put it by your side.

This comes naturally.

Facial expressions comes naturally

because there's an innate component.

And yes, you have to learn how to dissociate the two,

communicate something angry with your hands

or with your face,

but, you know, politely with your voice.

It's very hard to separate those two,

because there is that innate component

that brings them together.

So it's like an email, too.

You're emailing and someone says something by email,

someone can interpret that angrily or gently,

and it becomes ambiguous.

The facial expressions get rid of that ambiguity.

- So glad you brought that up

because my next question was,

and is about written language.

The first question I'll ask is when you write,

either type or write things out by hand,

do you hear the content of what you want to write

in your head?

Just, you personally.

- Yes, I do.

Yeah, and I know that I do,

because I was trying to figure out a debate about this issue

and trying to resolve the debate

with my own self experimentation on me.

- I asked that because,

a quite well-known colleague of ours,

Karl Deisseroth at Stanford,

who's been on this podcast, you know,

his optogenetics fame and psychiatry fame, et cetera.

- Yeah, I know him. - Yeah, he sends his regards.

- Okay. [laughs]

- Told me that his practice for writing

and for thinking involves a quite painful process

of forcing himself to sit completely still

and think in complete sentences,

to force thinking in complete sentences.

And when he told me that,

I decided to try this exercise and it's quite difficult.

First of all, it's difficult

for the reason that you mentioned,

which is that with many thoughts,

I want to look around

and I start to gesticulate with my hands, right?

So there it is, again,

the connection between language and hand movement,

even if one isn't speaking.

And the other part that's challenging is

I realize that while we write in complete sentences,

most of the time, we'll talk about how that's changing now.

- Right. - In texting, et cetera.

That we don't often think in complete sentences,

and specifically in simple declarative sentences,

that a lot of our thoughts would be,

if they were written out onto a page

would look pretty much like passive language

that a good copy editor or a good editor would say,

ugh, like we need to cross this out,

make this simple and declarative.

So what I'm getting at here is

what is the process of going from a thought to language,

to written word?

And I also wanted to touch on handwritten versus typed,

but thought to language, to written word.

What's going on there?

What do we know about the neural circuitry?

And I was going to ask, why is it so hard?

But now I want to ask why is this even possible?

It seems like a very challenging

neural computational problem.

- Yeah, yeah.

And coming from the linguistic world,

and even just the regular neurobiology world,

going back to something I said before

about a separate language module in the brain.

You know, there was this thought or hypothesis

that this language module

has all these complex algorithms to them.

And they're signaling to the speech circuit,

how to produce the sounds,

the hand circuit, how to write them or gesture,

the visual pathway on how to interpret them from reading

and the auditory pathway for listening.

I don't think that's the case, all right.

And you know, that this thinking where

there's this internal speech going on.

What I think is going on is

to explain what you're asking is about,

that I'm going to take it from the perspective,

reading something.

You read something on a paper.

The signal from the paper goes through your eyes.

It goes to the back of your brain,

to your visual cortical regions eventually.

And then you now got to interpret that signal

in your visual pathway of what you're reading.

How are you going to do that in terms of speech?

That visual signal then goes to your speech pathway

in the motor cortex in front here, in Broca's area.

And you silently speak what you read

in your brain without moving your muscles.

And sometimes actually, if you put electrodes, EEG,

EMG electrodes on your laryngeal muscles,

even on birds, you can do this,

you'll see activity there while reading

or trying to speak silently,

even though no sound's coming out.

And so your speech pathway

is now speaking what you're reading.

Now to finish it off,

that signal is sent to your auditory pathways

so you can hear what you're speaking in your own head.

- That's incredible.

- And this is why it's complicated

because you're using like three different pathways,

the visual, the speaking motor one,

and the auditory to read.

Oh, and then you got to write, right?

Okay, here comes the fourth one.

Now the hand areas next to your speech pathway

has got to take that auditory signal

or even the adjacent motor signals for speaking

and translate it into a visual signal on paper.

So, you're using at least four brain circuits,

which includes the speech production

and the speech perception pathways to write.

- Incredible.

And finally, explain to me why,

so I was weaned teaching undergraduates,

graduate students and medical students

and I've observed that when I'm teaching,

I have to stop speaking

if I'm going to write something on the board.

I just have to stop all speaking completely.

- [Erich] Right.

- It turns out this is an advantage to catch

because it allows me to catch my voice.

It allows me to slow down a bit, you know,

breathe and inhale some oxygen and so on

because I tend to speak quickly

if I'm not writing something out.

So there's a break in the circuitry for me,

or at least they are distinct enough

that I have to stop and then write something out.

- Yes, that does imply competing brain circuits

for your conscious attention.

- We have colleagues up at Columbia Med

who are known, at least in our circles,

for voice dictating their papers, not writing them out,

but just speaking into a voice recorder.

I've written papers that way.

It doesn't feel quite as natural for me

as writing things out. - Yeah.

- But not because I can go quickly from thought

to language to typing.

I type reasonably fast.

I can touch type now.

I don't think I ever taught my,

I think I taught myself.

I never took a touch typing course.

But it just sort of happened.

Now, I think, my motor system

seems to know where the keys are

with enough accuracy, that it works.

This is remarkable to me that any of us can do this.

But when it comes to writing,

what I've found is that if my rate of thought

and my rate of writing are aligned nicely, things go well.

However, if I'm thinking much faster than I can write,

that's a problem.

And certainly, if I'm thinking more slowly

than I want to write, that's also a problem.

And the solution for me

has been to write with a pen.

I'm in love with these.

And I have no relationship to the company,

at least not now, although if they want to come,

you know, if they want to work with us,

I love these Pilot V5, V7's

because not necessarily because of the ink

or the feel, although I like that as well.

But because of the rate that it allows me to write,

they write very well slowly,

and they write very well quickly.

And so I have this theory,

supported only by my own anecdata,

no peer reviewed study,

that writing by hand is fundamentally different

than typing out information.

Is there any evidence that this motor pathway for writing

is better or somehow different

than the motor pathway for typing?

- Yeah, that's interesting.

And I don't know of any studies.

I have my own personal experience as well,

but trying to put this into the context,

if I had to, you know,

design an experiment to test the hypothesis here that,

you know, to explain your experience and mine,

is that writing by hand,

I would argue, requires a different set of less skills

with the fingers than typing.

So you have to coordinate your fingers more

in opposite directions and so forth with typing,

but also writing by hand requires more arm movement.

And so therefore, I would argue that

the difficulty there could be

in the types of muscles and the fine motor control

you need of those muscles

along with speaking in your brain at the same time.

- So basically, I'm a course, I'm a brute.

So it makes sense that I would have,

a more primitive writing device would work.

- That's right, yes.

But, let me answer this in terms

of my own personal experience, right.

What I find is I can write something faster by hand

for a short period of time, compared to typing.

And that is because I think

I run out of the energy in my arm movements

faster than I run out of muscle energy

in my finger movements.

And I think it takes longer time

for us to write words with our fingers,

because, and in terms of the speech.

So I think your writing,

whether it's by hand or typing and your speech,

they only will align very well

if you can type as fast as you can speak

or write as fast as you can speak in your head.

- I love it.

So what you've done, if I understand correctly,

is created a bridge between thought and writing,

and that bridge is speech.

- That bridge is speech, that's right.

That's right.

When you're writing something out,

you're speaking it to yourself.

And if you're speaking faster than you can type,

you've got a problem.

- Interesting.

I do a number of podcast episodes that are not with guests,

but solo episodes.

And as listeners know,

these are very long episodes, often two or more hours.

And we joke around the podcast studio

that I will get locked into a mode of speech

where some of it is more collaborative and anecdotal

and then I'll punch out simple declarative sentences.

I find it very hard to switch from one module to the next.

The thing that I have done

in order to make that transition more fluid

and prep for those podcast episodes

is actually to read the lyrics of songs

and to sing them in my head

as a way of warming up my vocal chords.

But luckily for those around me, when I do that,

I'm not actually singing out loud.

And so this, what you're telling me

supports this idea that even when we are imagining singing

or writing in our mind,

we are exercising our vocal chords.

- You're actually getting little low potentials

of electrical currents reaching your muscles there,

which also means you're exercising

your speech brain circuits too, without actually, you know,

going with the full-blown activity in the muscles.

- Incredible. - Yeah.

And this idea of singing helps you as well.

Even with Parkinson's patients and so forth,

when they want to say something,

singing or listening to music helps them move better.

And the idea there is that the brain circuits for singing,

or let's say the function of the brain circuits for speech

being used for singing first is the more ancestral trait.

And that's why it's easier to do things with singing

sometimes than it is with speaking.

- I love it.

Stutter is a particularly interesting case

and one that every once in a while,

I'll get questions about this from our audience.

Stutter is complicated in a number of ways,

but culturally, and my understanding from these emails

that I receive is that

stutter can often cause people to hide and speak less

because it can be embarrassing.

And we are often not patient with stutter.

We also have the assumption that if somebody's stuttering,

that they're thinking is slow,

but it turns out there are many examples,

historically of people who could not speak well,

but who were brilliant thinkers.

I don't know how well they could write,

but they found other modes of communication.

I realize that you're not a speech pathologist or therapist,

but what is the current neurobiological

understanding of stutter

and, or what's being developed

in terms of treatments for stutter?

- Yeah, so we actually accidentally

came across stuttering in songbirds.

And we've published several papers on this

to try to figure out the neurobiological basis.

The first study we had was a brain area

called the basal ganglio,

or the striatum part of the basal ganglia

involved in coordinating movements,

learning how to make movements,

when it was damaged in a speech-like pathway in these birds,

what we found is that they started to stutter

as the brain region recovered.

And unlike humans,

they actually recovered after three or four months.

And why is that the case?

Because bird brains undergoes new neurogenesis

in a way that human or mammal brains don't.

And it was the new neurons that were coming in

into the circuit, but not quite, you know,

with the right proper activity

was resulting in this stuttering, in these birds.

And after it was repaired,

not exactly the old song came back after the repair,

but still it recovered a lot better.

And it's now known,

they call this neurogenic stuttering in humans,

damage to the basal ganglia

or some type of disruption

to the basal ganglia at a young age,

also causes stuttering in humans.

And even those who are born with stuttering,

it's often the basal ganglia that's disrupted

than some other brain circuit

and we think the speech part of the basal ganglia.

- Can adults who maintain a stutter from childhood

repair that stutter?

- They can repair it with therapy,

with learning how to speak slower,

learning how to tap out a rhythm.

And yeah, I'm not a speech pathologist,

but I started reading this literature

and talking to others, that you know,

colleagues who actually study stuttering.

So yes, there are ways to overcome the stuttering

through, you know, behavioral therapy.

And I think all of the tools out there

have something to do with sensory motor integration,

controlling what you hear with what you output

in a thoughtful controlled way helps reduce the stuttering.

- There are a couple examples from real life

that I want to touch on,

and one is somewhat facetious,

but now I realize, is a serious neurobiological issue,

serious meaning I think interesting.

Which is that every once in a while,

I will have a conversation with somebody

who says the last word of the sentence along with me.

And it seems annoying in some instances,

but I'm guessing this is just a breakthrough

of the motor pattern

that they're hearing what I'm saying very well.

So I'm going to interpret this kindly

and think they're hearing what I'm saying.

They're literally hearing it in their mind

and they're getting that low-level electrical activity

to their throat.

And they're just joining me

in the enunciation of what I'm saying,

probably without realizing it.

Can we assume that that might be the case?

- Well, I wouldn't be surprised so that, you know,

the motor theory of speech perception

where this idea originally came,

what you hear is going through your speech circuit

and then also activating those muscles slightly.

So yes, so one might argue,

okay, is that speech circuit now interpreting

what that person is speaking?

Now, you're listening to me

and is going to finish it off

because it's already going through their brain

and they can predict it?

That would be one theory.

And I don't think the verdict out there is known,

but that's one.

The other is synchronizing turn-taking in the conversation

where you're acknowledging that we understand each other

by finishing off what I say.

And it's almost like a social bonding kind of thing.

The other could be,

I want the person to shut up

so I can speak as well and take that turn.

And each pair of people have a rhythm to their conversation.

And if you have somebody who's over talkative

versus under talkative of vice versa,

that rhythm can be lost in them finishing ideas

and going back and forth.

But I think having something to do with turn-taking,

as well, makes a lot of sense.

- I have a colleague at Stanford who says

that interruption is a sign of interest.

[Erich laughs]

I'm not sure that everyone agrees.

I think it's highly contextual.

- [Erich] Yes.

- But there is this form of a verbal nod

of saying, hmm hmm or things of that sort.

And they're many of these.

And I'm often told by my audience, you know,

that I interrupt my guests and things of that sort.

Oftentimes, I'll just get caught in the natural flow

of the conversation, but. - Right.

Well, I think we've had pretty good turn-taking here,

I hope.

- So far so good. - I feel that way.

- I'm glad you feel that way,

because especially in the context of a discussion

about language. - Yes.

- It seems important.

Texting is a very, very interesting evolution of language

because what you've told us is that we have a thought,

it's translated into language.

It might not be complete sentences,

but texting, I have to imagine this is the first time

in human evolution where we've written with our thumbs.

So I don't know,

it seems more primitive to me than typing with fingers

or writing with hands, but hey,

who am I to judge the evolution of our species

in one direction or the other?

But the shorthand grammatically,

often grammatically deficient incomplete sentence form

of texting is an incredible thing to see.

Early in relationships, romantic relationships,

people will often evaluate the others text

and their ability to use proper grammar

and spelling, et cetera.

This often quickly degrades.

And there's an acceptance

that we're just trying to communicate through shorthand,

almost military like shorthand,

but with internally consistent between people,

but there's no general consensus of what things mean,

but, you know, WTFs and like,

and OMGs and all sorts of things.

- [Erich] Right.

- I wonder sometimes whether or not

we are getting less proficient at speech

because we are not required to write and think

in complete sentences. - Hmm hmm.

- I'm not being judgemental here.

I see this in my colleagues.

I see this in myself.

This is not a judgment of the younger generation.

I also know that slang has existed for decades,

if not hundreds of years.

But I also know that I don't speak the same way

that I did when I was a teenager,

because I've suppressed a lot of that slang,

not because it's inappropriate or offensive,

although some of it was, frankly,

but because it's out of context.

So what do you think's happening to language?

Are we getting better at speaking, worse at speaking?

And what do you think the role of things

like texting and tweeting

and shorthand communication, hashtagging,

what's that doing to the way that our brains work?

- Yeah, I think that,

well, one, in terms of, you know,

measuring your level of sophistication and intelligence

when you say OMG, right.

I think that also could be a cultural thing

that, ah, you belong to the next generation.

If you're an, you know,

or you're being cool,

if you're an older person, you know,

using OMG and other things that the, you know,

younger generation would use.

But if I really think about it clearly,

texting actually has allowed

for more rapid communication amongst people.

I think, without the invention of the phone before then,

or, you know, texting back and forth,

you had to wait days for a letter to show up.

You couldn't call somebody on the phone

and talk as well, you know?

And so this rapid communication

in terms of the rapid communication of writing in this case.

So I think actually,

it's more like a use it or lose it

kind of a thing with the brain.

The more you use a particular brain region or circuit,

the more enhanced.

It's like a muscle.

The more you exercise it, the more healthier it is,

the bigger it becomes and the more space it takes

and the more you lose something else.

So I think texting is not decreasing

the speech prowess,

or the intellectual prowess of speech.

It's converting it and using it a lot in a different way,

in a way that may not be as rich in regular writing,

because you can only communicate so much nuance

in short-term writing,

but whatever is being done,

you got people texting hours and hours

and hours on the phone.

So whatever, your thumb circuit is going to get pretty big,

actually. [laughs]

- I do wonder whether, you know,

many people have lost their jobs based on tweets.

- [Erich] Hmm hmm.

- The short latency between thought and action

and distribution of one's thoughts

is incredible. - Yes.

- And I'm not just talking about people

who apparently would have poor prefrontal top-down control.

This is geek speak by the way,

for people that lack impulse control.

But high-level academics,

I'm not going to point fingers at anyone.

But examples of where you see these tweets and you go,

what were they thinking? - Yep.

- So presumably, there's an optimal strategy

between the thought speech motor pathway,

especially when the motor pathway engages communication

with hundreds of thousands of people

and retweets in particular

and the cut and paste function

and the screenshot function

are often the reason why speech propagates.

- [Erich] Yep.

- So to me, it's a little eerie that,

just that the neural circuitry can do this

and that we are catching up a little bit more slowly

to the technology,

and you've got these casualties of that mismatch.

- I think that's a good adjective used, the casualties,

you know, of what's going on,

because yes, it is the case with texting,

what you're really losing there

is less so the ability to write,

but more the ability to interpret what is being written.

And you can over or under interpret

something that somebody means.

On the flip side of that, you know,

if somebody's writing something very quick,

they could be writing instinctually,

more instinctually, their true meaning,

and they don't have time to modify

and color code what they're trying to say.

And that's what they really feel

and as opposed to saying it in a more nuanced way.

So I think both sides of that casualty are present.

And that's a downturn, you know,

unintended negative consequence of short-term,

I mean, short-word communications.

- Yeah, I agree that this whole phenomenon

could be netting people that normally

would only say these things out loud

once inside the door of their own home.

- Right. - Or not at all.

- [Erich] Right.

- It's an interesting time that we're in.

These are these speech and language and motor patterns.

- So part of the human evolution for language,

I think this is all part of our evolution.

- That's right. - Yeah.

- So for those of you thinking terrible thoughts,

please put them in the world and be a casualty.

And for those of you that are not,

please be very careful with how proficient

your thought to language to motor action goes.

- [Erich] Yes. [laughs]

- Maybe the technology companies

should install some buffers, some AI-based buffers.

- Right, that's taking some EEG signals

from your brain while you're texting to say,

okay, this is not a great thought, slow down.

- Right, or this doesn't reflect your best state.

That brings me to

what was going to be the next question anyway,

which is we are quickly moving toward a time

where there will be an even faster transition

from thought to speech, to motor output,

and maybe won't require motor output.

What I'm referring to here

is some of the incredible work of our colleagues,

Eddie Chang at UCSF and others

who are taking paralyzed human beings

and learning to translate the electrical signals

of neurons in various areas,

including speech and language areas,

to computer screens that type out

what these people are thinking.

In other words,

paralyzed people can put their thoughts into writing.

That's a pretty extreme and wonderful example

of recovery of function. - Hmm hmm.

- That is sure to continue to evolve.

But I think we are headed toward a time,

not too long from now

where my thoughts can be translated into words on a page

if I allow that to happen.

- Yeah so, and Eddie Chang's work,

which I admire quite a bit and cite in my papers,

I think he's really one of those at the leading edge

of trying to understand within humans,

the neurobiology of speech.

And he may not say it directly, but you know,

I talked to him about this.

It supports this idea that the speech circuit

and the separate language module,

I don't really think that there's a separation there.

So with that knowledge,

yes, and putting electrodes into human brain

and then translating those electrical signals

to speech currents.

Yeah, we can start to tell what is that person thinking?

Why, because we often think in terms of speech.

And without saying words.

And that's a scary thought.

And now imagine if you can now translate

those into a signal that transmits something wirelessly

and someone from some distant part of the planet

is hearing your speech from a wireless signal

without you speaking.

So probably that won't be done in an ethical way,

who knows, you know?

But I mean, the ethics of doing that probably,

you know, might not happen, but who knows?

We have these songbirds, you know.

If we apply the same technique to them,

we can start to hear what they're singing

in their dreams or whatever,

even though they don't produce sound

so we can find out by testing on them.

- It's coming. - Yes.

- One way or another, it's coming.

For those listening who are interested

in getting better at speaking and understanding languages,

are there any tools that you recommend?

And here again,

I realize you're not a speech therapist,

but here I'm not thinking about

ameliorating any kind of speech deficiency.

I'm thinking, for instance,

do you recommend that people read

different types of writing?

Would you recommend that people learn how to dance

in order to become better at expressing themselves verbally?

You know, and feel free to have some degrees of freedom

in this answer.

These are obviously not peer-reviewed studies

that we're referring to, although there may be,

but I'm struck by the number of things

that you do exceedingly well,

and I can't help but ask,

well, the singing, which I realize it may,

your brother didn't pay me to say this,

may not be quite as good as your brothers yet,

but is getting, you'll surpass him,

I'm guessing at some point.

♪ Getting there ♪

- Getting there.

[both laughing]

Exactly, there you go.

You know, should kids learn how to dance

and read hard books and simple books?

What do you recommend?

Should adults learn how to do that?

Everyone wants to know how

to keep their brain working better, so to speak.

But also I think people want to be able to speak well

and people want to be able to understand well.

- Yeah, so what I've discovered personally, right,

is that, so when I switched

from pursuing a career in science from a career in dance,

I thought one day I would stop dancing,

but I haven't because I find it fulfilling for me,

you know, just as a life experience.

So ever since I started college,

you know, my late teens and early twenties,

I kept dancing even till this day.

And there've been periods of time,

like during the pandemic

where I slowed down on dancing and so forth.

And when you do that, you realize, okay,

there are parts of your body

where your muscle tone decreases a little bit and somewhat,

or you could start to gain weight.

I somehow don't gain weight that easily.

And I think it's related to my dance,

if that's meaningful to your audience.

But what I found is, you know,

in science, we like to think of a separation

between movement and action and cognition.

And there is a separation for you

between perception and production,

cognition being perception,

production being moving, right.

But if the speech pathways

is next to the movement pathways,

what I discover is by dancing,

it is helping me think.

It is helping keeping my brain fresh.

It's not just moving my muscles,

I'm moving or using the circuitry in my brain

to control a whole big body.

You need a lot of brain tissue to do that.

And so I argue,

if you want to stay cognitively intact into your old age,

you better be moving

and you better be doing it consistently,

whether it's dancing, walking, running,

and also practicing speech,

oratory speech and so forth or singing,

is controlling the brain circuits

that are moving your facial musculature.

And it's going to keep your cognitive circuits also in tune.

And I'm convinced of that from my own personal experience.

- Yeah, for me, long, slow runs

are a wonderful way to kind of loosen the joints

for long podcasts, especially the solo podcast,

which can take many hours to record.

And without those long slow runs,

at least the day before, or even the morning of,

I don't think I could do it, at least not as well.

- All right, well, you're experiencing something similar.

So that's an N of two.

- Yeah, N of two.

I'm tempted to learn how to dance

because there are a lot of reasons to learn how to dance.

- [Erich] Yes.

- And people can use their imagination.

I definitely want to get the opportunity

to talk about some of the newer work

that you're into right now about genomes of animals.

As you perhaps can tell

from my quite authentic facial expressions,

I adore the animal kingdom.

I just find it amazing.

And it's the reason I went into neurobiology, in part.

So many animals, so many different patterns of movement,

so many body plans, so many specializations,

what is the value of learning the genomes

of all these animals?

You know, I can think of conservation-based, you know,

schemes of trying to preserve these precious critters,

but what are you doing with the genomes of these animals?

What do you want to understand about their brain circuits?

And how does this relate to some of the discussion

we've have been having up until now?

- Yeah, I've gotten very heavily involved in genomes,

you know, not just to get at an individual gene

involved in the trade of interest, like spoken language,

but I realize that, you know,

nature has done natural experiments for us

with all these species out there with these various traits

and the one that I'm studying, like vocal learning,

has evolved multiple times among the animal kingdom,

even if it's rare, it's multiple times.

And the similar genetic changes occurred in those species.

But to find out what those genetic changes

that are associated with the trait of interests

and not some other trait like flying in birds,

as opposed to singing,

you have to do what's called comparative genomics,

even in the context of studying the brain.

And you need their genomes to compare the genomes

and do like a GWA, a genome-wide association study,

not just within a species like humans, but across species.

And so you need good genomes to do that.

Plus, I've discovered I'm also interested

in evolution and origins.

How did these species come about a similar trait

in last, you know, 300 million years or 60 million years,

depending who you're talking about.

And you need a good phylogenetic tree to do that,

and to get a good phylogenetic tree,

you also need their genomes.

And so, because of this,

I got involved in large scale consortiums

to produce genomes of many different species,

including my vocal learners

and their closest relatives that I'm fans of.

But I couldn't convince the funding agencies

to gimme the money to do that just for my own project.

But when you get a whole bunch of people together

who want to study various traits,

you know, heart disease,

or loss and gain in flight and so forth,

suddenly we all need lots of genomes to do this.

And so now that got me into a project

to lead something called the Vertebrate Genomes Project

to eventually sequence all 70,000 species on the planet.

And Earth BioGenome Project,

all eukaryotic species, all two million of them.

And to no longer be in a situation

where I wish I had this genome.

Now we have the genetic code of all life on the planet,

create a database of all their traits

and find the genetic association

with everything out there

that makes a difference from one species to another.

One more piece of the equation to add to this story

is what I didn't realize as a neuroscientist

were that these genomes are not only incomplete,

but have lots of errors in them,

false gene duplications,

where mother and father chromosomes

were so different from each other,

that the genome algorithm,

assembly algorithms treated them as two different genes

in this part of the chromosome.

So there are a lot of these false duplicated genes

that people thought were real, but were not

or missing parts of the genome

because the enzymes used to sequence the DNA

couldn't get through this regulatory region

that folded up on itself

and made it hard to sequence.

And so I ended up in these consortiums

pulling in the genome sequencing companies,

developing the technology to work with us

to improve it further

and the computer science guys

who then take that data and that technology,

and try to make the complete genomes

and make the algorithms better

to produce what we now just did recently

led by an effort by Adam Phillippy

is the first human Telomere-to-Telomere Genome

with no errors, all complete, no missing sequence.

And now we're trying to do the same thing with vertebrates

and other species.

Actually, we improved that before we got to the,

what we call telomere-to-telomere,

from one end of the chromosome to another.

And what we're discovering

is in this dark matter of the genome

that was missing before,

turns out to be some regulatory regions

that are specialized in vocal learning species

and we think are involved in developing speech circuits.

- Incredible.

Well, so much to learn.

And we're going to learn from this information.

Early on in these genome projects and connectome projects,

I confess I was a little bit cynical.

This would be about 10, 15 years ago.

I thought, okay, necessary,

but not sufficient for anything.

We need it, but it's not clear what's going to happen,

but you just gave a very clear example

of what we stand to learn from this kind of information.

And I know from the conservation side,

there's a huge interest in this

because even though we would prefer

to keep all these species alive rather than clone them,

these sorts of projects do offer the possibility

of potentially recreating species that were lost.

- [Erich] Right.

- Due to our own ignorance or missteps, or what have you.

- Yes, and along those lines,

because, you know, we got involved in genomics,

some of the first species that we start working on

are critically endangered species.

And I'm doing that not only for, you know,

perspectives to understand their brains

and the genes involved in their brain function,

but I feel like it's a moral duty.

So the fact that now I become more involved

in genome biology

and have helped develop these tools

for more complete genomes,

let's capture their genetic code now, before they're gone.

And could we use that information

to resurrect the species at some future time,

if not in my lifetime,

in some time in the future and generations ahead of us.

And so, in anticipation of that,

we create a database, we call the GenomeArk

and no pun intended like Noah's Ark,

meant to store the genetic code

as complete genome assemblies as possible

for all species on the planet

to be used for basic science,

but also some point in the future.

And because of that,

funding agencies or private foundations

that are interested in conservation

have been reaching out to me now, a neuroscientist,

to help them out in producing high quality genome data

of endangered species that they can use,

like Revive & Restore,

who want to resurrect the passenger pigeon

or Colossal, who wants to resurrect the wooly mammoth.

And so we're producing high quality genomes

for these groups, for the conservation projects.

- What a terrific and important initiative.

And I think for those listening today,

they now certainly understand the value

of deeply understanding the brain structures

and genomes of different species.

Because I confess,

even though I knew a bit of the songbird literature,

and I certainly understand

that humans have speech and language,

I had no idea that there was so much convergence

of function, structure and genomes.

And to me, you know, I feel a lot more like

an ape than I do a songbird. - Right.

- And yet here we are with the understanding

that there's a lot more similarity

between songbirds and humans

than I certainly ever thought before.

- Yeah, something very close to home for us humans,

I can give you an example of is evolution of skin color.

And skin color, we use it unfortunately,

for racism and so forth.

We use it also for good things to let in more light

or let out less light depending on the part of the planet,

you know, our population evolved in.

And most people think dark-skinned people

all evolved from the same dark-skinned person

and light-skinned people all evolved

from the same light-skinned person,

but that's not the case.

Dark skin and light skin amongst humans

has evolved independently multiple times,

like in, you know, the Pacific islands versus Africa.

And it's just depending on the angle

of light hitting the Earth

as to whether you need more protection from the sun

or less protection,

that's also associated with Vitamin D synthesis in the skin.

And so, and each time,

where darker or lighter skin evolved independently,

it hit the same gene, you know,

the mela [finger snaps].

- Melanin. - Melanin receptors.

That's right, yes, yeah.

Genes that are involved in melanin in formation.

And so those genes evolve some of the same mutations,

even in different species.

It's not just humans.

In equatorial regions, they are darker-skinned animals

than going away from the equator.

- Oh, right, I think of Arctic foxes

and things of that sort. - Yep, that's right.

That's right, polar bears, you know,

and so some of the same genes are used

in evolutionary perspective to evolve in a similar way

within and across species.

- Incredible. - Yeah.

And that's same thing happening in the brain too.

Language is no exception.

- Well, I have to say,

as somebody who is a, you know, career neuroscientist,

but as I mentioned several times now,

who also adores the animal kingdom,

but is also obsessed with speech and language,

at a distance not as a practitioner of music and dance,

this has been an incredible conversation

and opportunity for me to learn.

And I know I speak for a tremendous number of people

and I just really want to say,

thank you for joining us today.

You are incredibly busy.

It's clear from your description of your science

and your knowledge base,

that you are involved in a huge number of things,

very busy, so thank you for taking the time

to speak to all of us.

Thank you for the work that you're doing,

both on speech and language,

but also this important work on genomes

and conservation of endangered species and far more.

And I have to say,

if you would agree to come back

and speak to us again sometime,

I'm certain that if we were to sit down even six months

or a year from now, there's going to be a lot more to come.

- Yeah, we have some things cooking

and thank you for inviting me here

to get the word out to the community

of what's going on in the science world.

- Well, we're honored and very grateful to you, Erich.

Thank you.

- You're welcome.

- Thank you for joining me today for my discussion

with Dr. Erich Jarvis.