Part 1 - Why do we talk? - BBC Horizon

[♪ mysterious/mystical music]

Man: It is probably the most amazing thing you do,

and it defines you as being human.

Woman: And you do it with ease,

so much so you barely notice you're doing it.

Toddler: Apple. Parents: Yeah! Apple!

Woman: Your ability to talk.

Man: Or more precisely,

the way you use language.

[Speaking in different languages]

Woman: Language.

Robotic Male Voice: Hi, baby.

Narrator: From the moment we're born,

we have language in our lives.

Robotic Female Voice: Hi, baby.

Narrator: A unique ability that defines us

as human.

Man 2: I can walk up to someone I don't know

and I can make a sequence of noises

that I've never made before

by pushing air through my mouth.

I will take a thought in my head

and make it go into their head.

And that's an incredible trick.

[Dog barks]

Narrator: Other animals may use sounds

to communicate.

We're the only ones on the planet

who can talk.

Woman 2: Speech and language distinguishes us

from all other species.

We are not only using words

to be able to express ourselves,

but we're really expressing

our thought processes that are unique to ourselves.

Narrator: For most of us,

it just happens.

Woman 3: It's such a sophisticated skill,

and yet children learn it so easily

with minimal effort at all.

Girl: That's bubby.

Woman 3: And when you start thinking about it

it's quite miraculous how the brain does it.

Narrator: But despite decades of research,

how we learn to talk remains a mystery.

How did this ability evolve?

Why is it uniquely human?

And is it something we're born with

or something that we learn?

Man 2: It strikes me as surprising and odd

that we know an enormous amount

about for example,

the first fractions of a second

in the history of the universe,

but we really know very little at all

about what makes us human

and where language comes from.

Toddler: I fell down.

Daddy, I don't...

[Toddler oohing and ahhing]

Narrator: The wonder of language

may not yet be fully understood.

[Baby cawing and cooing]

Baby: Ca. Ca-ca. Car-car.

Narrator: But how we start to talk

is now being observed minute by minute

for the first time.

Cognitive scientist Deb Roy,

realized that to discover

how a child learns to speak,

he'd have to be to see and hear them

24 hours a day.

His solution was to take the extraordinary step

of turning his own home into a language laboratory.

And his guinea pig was his own son.

[Toddler undecipherable]

Roy: My wife and I were expecting our first child

and we had many conversations around

you know, would this possible?

Could we set up our home as an observation space

and actually capture this kind of

rich longitudinal record of

our own child's development from birth?

And that's what we set up to do.

Narrator: And so was born the speech home project.

The most ambitious language observation experiment

ever seen.

Cameras and microphones recorded every second

of Deb's son's life

from the moment he was born

until he was 3 years old.

Capturing in precise detail the process

of how we learn to talk.

Son: Ba. Boo. Boo. Ba. Boo. Booba. Boobal.

Roy: Blue ball, yeah.

Narrator: From the earliest unintelligible babble

to the emergence of a very first word.

Wife: You want it?

Toddler [whines]: Ba.

Roy: Apple.

Toddler: Apple. Parents: Yeah! Apple.

Roy: My interest going in was

really to understand the earliest stages

of languages formation.

And the typical development stages in language

a child will go from babbling

to using single words

usually as a complete request and descriptions.

And then, from that they will start

what's called a two-word stage

where they'll put two words together

like "more milk,"

and from that very quickly more complex

grammatical structures emerge.

My focus and my aim was to capture

the phase up to the two word utterance.

And that could happen anywhere

between 2nd and 3rd birthday.

It turned out my son was an early talker,

so by the time his 2nd birthday arrived

we had the main data set we wanted.

Narrator: By the time recording was complete,

more than 240,000 hours of information

and 16 million words had been collected.

Roy: It's a lot of data,

but in it's raw form,

it's useless.

And so, the challenge is this now sets up for us

is how to start extracting the right kind

of metadata.

Transcripts of who said what.

Annotations of where those people were.

Annotations of how they're moving

and the relationships that they were in

as they were speaking.

And these are the tools that we're now building

to analyze the raw data,

and from that we're starting to see some early

insights into the patterns of language development.

Narrator: Despite the mountains

of video footage,

Deb Roy is already uncovering

the intricate effect daily life

has on language development.

It seems cooing to your baby

is not just instinct,

it's essential.

In the months leading up

to their son's first words,

he and his wife unconsciously

simplified their speech.

Then as their son's own speech develops,

they began to use longer sentences again,

mirroring the child's own development.

Toddler: Green car.

Roy: What's that over there?

Over there. That ball.

Toddler: Gren bal.

Roy: Ooohhh.

Narrator: For the very first time,

the analysis has also enabled

Deb to piece together the precise emergence

of individual words.

Charting how a new word is born.

Mother: Okay, water. Wa-ter.

Toddler: Ga-ga-ga-ga?

Roy: So, my son around his first birthday

started using the sound "ga-ga"

to indicate "water."

And then over the next several months,

learned to slowly approximate

the proper speech form.

Mother: Water.

Roy: Just like time lapsed video

lets you capture a flower blossoming,

what we're going to hear

is the blossoming of a speech form.

Mother: Okay, water. Wa-ter.

Roy: Water?

Roy: Water?

Mother: Water.

Roy: That's water.

Narrator: It will takes years for Deb Roy

and his team to analyze all of the data.

But buried within this footage

are the secrets of how we learn language.

If the patents can be unlocked,

then once this remarkable project is complete,

we will have the clearest understanding yet

of how a child achieves the remarkable feat

of learning to talk.

[♪ mysterious/mystical music]

Woman 1: By the time a child is 5,

they'll know as many as 5,000 words.