All language subtitles for BBC Secrets of the Brain - Jim Al-Khalili - Series 1 Episode 2 (2025) Full Episode Documentary HD.en

[Music]

I'm Jamal Khalili, a professor of

theoretical physics, and I'm exploring

how the most complex objects we know of

in the universe, our brains, evolved.

>> This is what your head looks like

inside.

[Music]

In the last episode, we went from the

first neurons to the early mammal brain.

Wow.

In this episode, I learn how life in the

forests shape our brains

[Music]

and how our primate ancestors solve

problems to survive.

>> Look how quick.

>> Oh my word.

With my wife, I investigate how

relationships made us intelligent.

>> You're not a showoff like me, is that?

>> No, I'm not a show off like you. Not

many people are.

>> It's a long

>> and how our brains are wired to be

social.

>> The single best predictor of how long

you're going to live into the future.

It's simply the number and quality of

close friendships.

As we build artificial intelligence

vying to overtake our brains,

I want to find out what makes the thing

in our skulls so special.

This is my brain and this is its 600

millionyear story.

[Music]

66 million years ago, the Earth lay in

desolation and darkness. An asteroid

smashed into the surface of the planet.

Soot and ash and vaporized bedrock,

dimming the sun. Perhaps threearters of

all life on Earth was wiped out,

including the gigantic dinosaurs which

had ruled the world.

But as the earth slowly recovered,

forests returned and spread across the

land.

And with the dinosaurs gone, small

creatures colonized this new habitat.

Among them were our ancestors. Now,

here's the mystery. How did they survive

this catastrophe?

>> Dr. Ornella Bertron studies the

extremely limited evidence that survives

from this dark period in the Earth's

history.

That is not an easy job. You've drawn

the short straw when it comes to

paleontology. Right.

>> Definitely because it's very difficult.

There's just not that many fossils. We

find teeth. We find like a bit of bone

sometimes. One group that I'm really

interested in understanding is a group

called plesiaforms. They were little

like warm-blooded mammals.

Plesiaforms resembled modern shrews.

It's thought they used their sharp claws

to cling onto the branches of trees in

the primeval forest. They're the closest

we found to the predecessors of all

today's primates, including us.

Orella studies their skulls, but she

doesn't have many to work with.

>> We really have like six good specimens

so far.

>> Six specimens

>> in total these creatures.

>> Yeah. Yeah. So that's that's very

little, but we can learn so much just

from those different skulls.

Ornella has a 3D print of the skull of a

specimen called Ignatius Grey Bullanis

upscaled so we can see the details. By

scanning the cavity inside the skull,

she's been able to produce a cast of the

missing brain.

>> Tada. It's amazing, isn't it?

>> Is incredible.

>> It gave us like so much information

about what actually those animals were

able to do. And for example, these

structures in front.

>> I was just going to ask you there funny

little knobbybly bits at the front.

>> Yes, we still have those structure. The

allactory bulbs in humans.

>> They're old factory. Okay. So that's for

smell the smell.

>> Yeah. Yeah. Exactly.

>> Plesiodapforms had very large smell

processing systems.

Orella believes they may have scavenged

at dusk and at night when a strong sense

of smell is very useful.

I imagine them being like quietly moving

among the branches. That's kind of yeah

how I see them.

>> For this documentary, I've had my brain

scanned and I've been carrying around

a a 3D printed version of my brain.

>> Wow.

>> Which is here, which I'm very proud of.

>> I would be that's amazing.

>> Which we can put alongside Ignatius. I'm

not Look, I'm not boasting. There's been

some evolution.

>> So, just a little bit.

I'm interested in a particular part of

the brain, the neoortex.

>> So here we have the neoortex of

Ignatius. It's very small. It's actually

just this part of the brain.

>> In Ignatius, it covers about 20% of the

top of the brain. That's very different

in a human brain, isn't it?

>> Very, very different. You can see like

the neocortex in humans actually is

covering the entire rest of the brain.

This is amazing how big that it got in

humans.

A rudimentary neoortex helped early

mammals analyze the world around them

and respond to it. For humans, it's

become the seat of advanced thinking,

reasoning, and perception. But the

mystery is why did our neoortex grow so

large compared to any other mammal?

There's a compelling theory and it's to

do with climate change.

About 56 million years ago, greenhouse

gases released by volcanic activity

caused sudden global warming of up to

5°.

It was the beginning of the Eosene era,

a time of astonishing changes.

In the hop house environment of the

Eioene, dense rainforests spread around

the world. They even reached high enough

latitudes to be within what is today the

Arctic Circle. And as with the

rainforests of today, life proliferated.

Just look at these extraordinary fossils

found near Frankfurt in Germany, dating

nearly 50 million years ago. They give

us an incredible insight into the

competition which raged in the forests

of the early eosene.

[Music]

There were birds and agile tree dwelling

rodents. There were highly dangerous

predators, too. All of this meant fierce

competition for food and resources. And

with all these new predators around, it

was much more dangerous, too. Only those

creatures able to adapt would survive.

[Music]

In these changed circumstances, simply

staying alive would take brains as well

as brawn.

[Music]

As I'm very quickly finding out, a tree

is a tricky place to call home. It's

actually quite difficult moving around

up here. It It doesn't just take

physical strength. You need judgment.

You need to decide whether a branch is

strong enough to hold your weight,

whether it's too wobbly. You need to

plan a route through the trees.

On top of the physical, the mental

agility you need, coping with the

incredibly complex visual field of a

canopy of leaves poses yet more

problems.

While finding it really difficult

peering through the leaves and twigs and

branches, keeping an eye out for

predators as well as foraging for food

must have been a real challenge.

In the face of these evolutionary

pressures, a new kind of creature

appears in the fossil record of the

eosene.

They're called crown primates, the

forerunners of all today's primates,

including, of course, us.

[Music]

Is this the way we sit?

Like this? Early primates were well

adapted to life in the trees.

What's interesting is the way he's

grasping the branch.

[Music]

During the eosene, primates evolved

gripping hands and feet with nails.

They're much more dextrous. They're able

to hold on to this branch. It also means

they can use these hands to find food,

to forage, to manipulate objects much

more easily.

[Music]

The other thing to notice is that they

have eyes at the fronts of their heads,

not on the side.

Animals with eyes on the side of their

heads have a wider field of view and can

spot predators better.

But eyes at the front help with what's

ahead of you, judging the distance to

the next branch or locating food.

[Music]

The effect of millions of years of tree

dwelling is clear when we look at the

fossil record. This is the brain cast of

Ignatius, the plesapp we've already seen

clambering around the forest in the

years after the dinosaur extinction.

And this is the brain cast of a primate

called runa. It evolved around 20

million years after Ignatius.

With Ignatius, the neoortex covered 20%

of its brain. With runa it now covers

half its brain.

[Music]

The neoortex analyzes visual data

[Music]

and it has many other functions besides.

It works in extraordinarily complex ways

which we take for granted in our

everyday lives.

Take for instance what happens inside

our brains when we do something as

deceptively simple as reaching out and

grabbing an apple. It's actually far

more complicated than you might think.

I'm getting an extraordinary insight

into what's involved when we reach out

and grab something.

Dr. David Pitcher at the University of

York has carried out a functional MRI

which measures the way the blood flows

in my brain.

>> Okay, Jim, this is going to be an

8-minute scan. while he plays me videos

of reaching out and grasping an apple.

>> My colleague Al is going to put this uh

hello right on your head.

>> Yeah, I think so.

>> Then he uploads my results to this

machine

>> which uses spatial recognition

technology to guide me around my own

brain.

>> Now where she points to with that um

pointer, this is what your head looks

like inside.

Lovely death mask as well, isn't it?

>> Yeah. Oh, I can rotate that for you as

well, so we can see.

>> My scan shows astonishing activity

across my cerebral cortex as I watch the

video.

First, David shows me how my visual

processing works. A complex system which

really started to develop with those

early primates.

light hits your eyeball that's then

converted into neuronal signaling. That

information is then sent down the optic

nerve all the way to primary visual

cortex which in humans is right at the

back of your head.

>> As I was looking at the apple, my visual

cortex connected with another part of my

brain which helps us recognize objects.

>> You see this pathway that lights up?

This is the vententral object

recognition pathway.

>> And that pathway leads to the bit of the

brain where I'm storing information of

what apples look like.

>> Yeah.

>> The hard drive of my brain.

>> That's where we store everything. Yeah.

>> Then a second connection activates from

the visual cortex at the back of the

brain to the parietal lobe. The parietal

lobe judges where things are in space

around us and where our body is

positioned.

But to issue the orders to the body to

move, you need a third part of the

neoortex, the primary motor cortex.

>> This is your motor cortex. And there's

parts that control all the motor

function in your body. And if a male

moves the pen down the side of your

head, we're sort of tracking through

different parts of the motor cortex. And

where we come to uh sort of roughly

where Al is now, that's roughly where

the hand area is. So that's the

>> So different parts of the motor cortex

physically relate to different parts of

my body.

>> Exactly.

>> The visual, parietal, and motor cortex

all developed in our primate ancestors.

And a new area of the neoortex was also

beginning to evolve. It would become the

most sophisticated cognitive area of our

brains.

>> The other thing you have to do is be

able to plan and control a motor

actually. So for Mel brings the the

pointer forward a little bit is the

prefrontal cortex. It's where we do all

our thinking. It's where cognitive

control happens. The voice inside your

head.

So just picking up an apple means the

visual cortex, the parietal lobe, the

motor cortex, and the preffrontal cortex

all have to work together.

So four different parts of the brain are

all involved in the simple action of

reaching out picking up an apple. Visual

cortex, parietal lobe, motor cortex,

frontal cortex.

[Music]

From 40 million years ago, the creatures

we now call monkeys were evolving.

Their neoortex was becoming bigger and

more complex in structure.

In today's primates, the larger the

brain, the denser and more closely

packed the neurons, the more networks

they develop, the clever they become.

So, what were the driving factors which

caused some primates to evolve

differently from others? And why did

humans evolve the most intelligence? One

theory has to do with the ability to

find the best, most calorific food. And

it's something we can study by looking

at two species of modern monkeys side by

side.

>> So this is the viewing deck. And here we

can see both species, the capacins and

the squirrel monkeys.

There are relatives, but if we study

enough of our primate relatives, we can

start to make inferences about what our

ancestors, our primate ancestors might

have been like.

>> This is the living link center at

Edinburgh Zoo. Professor Amanda Seed

studies these species side by side to

try to understand the story of our own

brains.

>> The caper monkeys are our larger

monkeys. They're more robust. They have

this uh characteristic dark coloring on

their head and the little tufts at the

front. The squirrel monkeys, on the

other hand, they're smaller. They're

more slender. Look a little bit like

they've been dipped in chocolate.

Capacin monkeys and squirrel monkeys

evolved together in the same place, the

forests of the new world. And yet,

capacins have a much larger neoortex

compared to their body size and exhibit

greater intelligence. The question is

why? And what might that tell us about

the evolution of our own brains? Amanda

and her staff have devised a challenge

these monkeys haven't encountered

before.

They've hidden food in papia mâe boxes.

The challenge is which species will

figure out that there's food inside and

manage to get it.

>> Straight in.

>> Thank you very much.

>> Straight away the capachins have come

out.

They're very, very curious and their

first thought is, "Can I break it? Is

there food inside?"

>> Meanwhile, the squirrel monkeys hang

around on the sides, and not one of them

looks inside a box. Instead, they wait

for the capins to finish feasting, and

they pick up scraps from their table.

Amanda believes today's test has helped

confirm a theory which links

intelligence to diet.

>> The capacins rely on fruit to a much

greater extent than the squirrel

monkeys. The squirrel monkeys eat fruit

as well, but their diet is largely

comprised of insects.

>> The squirrel monkeys just have to wait

for an insect to come along and grab it,

and that happens a lot. But fruit only

appears a few months every year. is

found around the forest in patches in

often hard to find places. So in order

to find it, you have to remember and

plan ahead.

>> An ability to map your environment in

space and even time to be able to

predict when those resources are going

to become available now becomes useful.

And so now we have more selective

pressure for areas of the brain that can

deal with that. The penny is starting to

drop for me now that it's not so much

that they have larger brains, they're

smarter, therefore they're able to

figure out things like, you know, how to

find food. The need to look for food has

stimulated the growth of a larger brain

over millions of years.

>> Over millions of years.

>> So it may be that at some point in our

evolution, our ancestors were like the

capacins. They concentrated more and

more on fruit, high calorie fuel for

growing brains. But it takes more

intelligence to find.

By 25 million years ago, the first apes

were evolving. Ape brains are generally

larger than monkeys, and they have more

complex structures and networks.

[Music]

It's now thought that around this time

our ancestors took their first baby

steps towards one of our most important

cognitive abilities, complex spoken

language.

I've come to see something very

unexpected which might provide a vital

clue.

These gorillas live at Port Limb Safari

Park in Kent.

I'm with Professor Jillian Forester

who's been studying the primates at this

sanctuary for 20 years.

>> I really like working here at Portland

because it's it feels like more of a

collaboration with the gorillas. Um we

work together, but they're in an

environment that really suits them. The

enclosure was made for them, not for

people to view them.

>> Right.

It's lunchtime and the gorillas have an

unusual treat.

[Music]

Nettles, which they find very tasty.

They found a clever strategy to deal

with their stinging leaves.

[Music]

They strip the nettles off the stem in

one direction, a direction which doesn't

trigger the spines so they don't get

stung.

One gorilla decides to literally walk

away with her spoils.

>> Look at her go.

>> Fantastic.

>> We follow this gorilla to the inside

area where we catch a glimpse of a more

complex form of nettle preparation.

rolling the leaves into a ball to crush

the stinging spines.

This method of preparing nettles has

been recorded in many different gorilla

groups.

And you want me to try this, don't you?

>> Okay. Right. Let's see how we go.

>> Let's see.

>> Ah, well, okay. There we go. I was so

careful not to get stung, which I think

I've survived that I've dropped the

leaves.

>> Dropped the leaves. Yeah. Yep.

>> Not as delicate as you, but nearly

there. I think it's interesting because

eating the nettles requires the gorillas

to take certain actions in order to not

get stung.

>> Okay,

>> we could think of that as almost like

what we'd call a syntax in language.

When I speak, these are motor action

sequences. So my mouth has to make the

right words at the right time in order

for you to understand what I'm saying.

This is a syntax and language. And this

is a syntax in its physical form.

Jillian has created some puzzle boards

which require an understanding of more

complicated syntax than nettle

stripping. The boards have a series of

cogs. The question is, can Great apes

turn them in the right direction, in the

right order to solve the puzzles?

>> Sorry, Jim, but you've got that the

wrong way around. Oh,

>> we're trying out her puzzle boards on

two orangutang brothers. Malu and

Haddie.

>> Oh, here they are.

[Music]

>> Oh,

>> yeah. Oh, they're right in there.

Straight away,

>> they've spotted the nuts, which Jillian

has put at the top of the puzzle boards.

But to get them out, they'll have to

maneuver the nuts to the bottom of the

board.

On his board, Paddyy tries using a twig

as a tool, but that's not going to work.

Over on the other board, Maddu lands on

the correct solution.

>> Oh, look at that.

>> Okay, that Mali has worked that out.

Well, well done.

>> Here we go.

Mie's gotten to the second set of cogs

and now he has Oh, look how quick

>> Oh my word.

>> I can't believe how fluid his movements

are.

>> He's getting to the last stage now. This

is the double cog, the exciting bit.

Will he think about Yes, he's thought

about which way to turn it.

>> Ah,

>> he's gone to the access point. This

could be the solution.

Okay, he's been

>> the last Oh, look at that stage. A big

brother has taken over.

>> Big brother's taken over and Pia's going

to get the reward.

>> But between them, they

>> kind of Yes, it was a collaboration.

>> Yeah. Jillian is convinced that our ape

ancestors developed the ability to solve

ever more complicated physical syntax

problems and were unknowingly building

the foundations of what would one day

become language.

Our ancestors split from orangutangs

around 17 million years ago and from

gorillas about 10 million years ago.

Again, climate change was bringing new

threats.

Millions of years of slow global cooling

meant that rainforests were retreating

to be replaced by open grasslands and

woodland.

Competition for the most nutritious and

calorific foods in the rainforest was

becoming ever more intense. Life for our

primate ancestors was getting harder and

harder.

Survival would now depend on making

finely balanced judgments based on

limited information about where to find

food.

To find out what mark climate change

made on our brains, I'm visiting the

chimpanzees who live at Bedongo Research

Unit at Edinburgh Zoo. Along with

bonobos, they're our closest primate

relatives.

I've been told I can play a game with

them to test their cognitive powers.

>> Not one of you said thank you yet.

>> So, I head to the indoor part of their

living quarters.

When the chimps start making their

noises, it is really loud in here.

The chimpanzees have complete freedom to

do as they like here, so I have to wait

to see if one of them wants to join me.

[Applause]

Eventually, four-year-old Missindi

decides she wants to play.

>> Miss Cindy,

>> look. To get the game started, I show

her two empty cups.

>> Nothing.

>> Then I cover them with a screen and put

a grape under one of them. Do

>> you feel lucky?

I'll put it under this one. Pretend to

put it under this one. She doesn't know

which cup has the grape, so she guesses

the cup on the left.

>> That one. Okay.

>> But now I complicate things.

>> I move this cup back.

>> I remove the cup she doesn't want and

offer her an alternative. A half grape.

Now, what do you want?

>> So, now she has a choice. Pick up a cup

which may or may not have a grape under

it or settle for a guaranteed half

grape.

This one. That one you want. Okay. Well,

look. Look what you could have won, but

unfortunately you have a half. She's

chosen the half grape. It's a safe

decision, but she's missed the chance of

winning a full one.

>> And that that's the choice they have to

make whether they want half a grape for

sure or a whole grape half of the time.

>> We play the game again. And this time

she sticks with the cup.

You're going for it, are you? Are you

confident?

>> Clever. Of course, Miss Cindi is having

to guess if the cup has a grape under

it. But now, what happens if I give her

more information to act on?

I offer her two cups with one grape as

usual. But this time, I show her that

one of them is empty.

Let's see. This is the This is going to

be the clincher. What you going?

Good girl. You Yes, you got it. Well

done. She immediately realizes that the

other cup must be hiding the grape. She

knew there was definitely a grape under

this one. So, choice between that and

the half grape. She's sticking with the

cup cuz she knows there's a grape under

it.

>> The chimps also play video games

which simulate complicated foraging

tasks.

looking for hidden fruits scattered

around a complex landscape.

>> The game is helping investigate the

theory that as the rainforests

retreated, the need to find scarcer food

required greater brain power, memory,

and planning ahead.

>> These games are posing a vital question.

Are the chimps able to keep track of

their own awareness of the world?

>> What they know and what they don't know.

The ability to keep track of what you

know and don't know is a vital and

mysterious part of human intelligence

known as metacognition.

It's something which particularly

interests the head of the research unit,

Professor Joseph Call. Metacognition is

the ability to monitor and control your

own thought processes, your own mental

content. There is a thing called in

metacognition uh that is called the tip

of the tongue phenomena. When somebody

ask you a question and you say I cannot

give you the answer but I know that I

know this answer. I just

>> all the time.

>> Yes, there you go. So this is

metacognition where even though you

cannot produce the answer, you know that

you you know the answer.

>> One theory states that our ancestors

developed metacognition as they solved

problems posed by the environment such

as finding fruit in changing landscapes.

It's thought this led to what's known as

theory of mind.

The awareness not just of your own mind

but others minds too.

>> It's about knowing about your own

processes but also uh imputing processes

to others. What others can see, what

others want, what others intend, what

others believe.

Thinking about others is a crucial step

towards becoming the socially connected

creatures which human beings are today.

Our ancestors split from the lineage of

chimpanzees around 6 to 8 million years

ago. After that came a huge change in

lifestyle, a change with astonishing

consequences.

No one knows exactly how, why, or when

it happened. But at some point during

the millions of years after our own

lineage split from that of chimpanzees

and bonobos, our ancestors left the

forests to make a new life out on the

open plains. They became bipedal,

walking up on two legs, so better able

to adapt to different terrains and

environments.

Between two and three million years ago,

Homohabilis was evolving. The first

human species,

they were developing areas of the

neoortex involved in planning, thinking,

problem solving, and we start to see

some astonishing results of improved

brain power.

Dr. Nada is an experimental

archaeologist. She works at the ancient

technology center in Dorset.

I'm meeting up again with Jillian

Forester.

She and Neda have both investigated the

fascinating links between tools and the

story of our brain.

>> So Jim, I'm really excited to introduce

you to Nata. She works in this beautiful

place and she actually teaches people

how to make these ancient tool sets.

>> Wow. Okay. Teach me.

>> So, we'll just start with a brief

history of some of the ancient types of

stone tool that were made by our

homminid ancestors. This is a core, a

flint core where sharp pieces, as you

can see down on the floor here, have

been knocked off. And these sharp pieces

were used as tools for cutting.

I want to know how much brain power it

takes to create the kind of tools which

our ancestors made. So Netta sets me a

task to make this halffinish handax

thinner.

>> So yeah, you can see that that's not

coming off.

>> It's not brute force.

>> It's not just brute forced

unfortunately.

Breaking the hammerstone.

Oh, so he's actually broken the

hammerstone and not the actual flint,

>> which is quite an achievement really.

So,

>> so as you can see, just hitting it as

hard as you can directly on the spot

which you want to remove

>> is it working

>> isn't the right approach.

>> Making the flint break in the direction

you want it to turns out to be extremely

complicated.

It might seem counterintuitive, but you

actually have to hit it from this side

to be able to thin it effectively.

>> And before we do that, even we need to

prepare a place for us to hit to take a

piece which should travel down there and

thin the flint. If I do it right, I just

need to do a few more preparatory

flakes.

>> Only after a few minutes of careful

preparation can she do this.

>> I'm going to hit on the top. And that's

taken a piece which hasn't traveled as

far as I want, but

>> is kind of isolated this spot a bit

more. So made it stick out a bit more.

>> A lot of times when people think of

stone tools, they're thinking of cave

men. They're thinking of mighty muscles,

big hard hit. But it's also about

planning and thinking ahead.

>> Jillian believes this supports the

theory that our ancestors were using

cognitive abilities which had developed

millions of years beforehand. As we've

seen, our shared primate ancestors had

likely already developed an ability to

master syntactical problems.

>> We've looked at nettle processing with

the gorillas. We've looked at puzzle

solving with orangutans. And now we're

looking here at stone tool making. They

might seem like very, very different

kinds of behaviors on the surface, but

they have a commonality.

And that common point is that they

require us to put actions in the right

order. And that's not different from how

we put words in the right order to make

meaning out of a sentence.

>> Jillian believes that during our

evolution, carrying out problem-solving

actions with our hands led to our

ability to produce spoken language.

She has intriguing evidence from brain

scans which she explains to me using the

3D model of my own brain.

This is your brain as you will know.

We've got the back of it here and the

front of it here. And running right down

the middle here is your motor cortex.

This is telling your body to move

effectively. The hand area and the mouth

area, they're really quite close to one

another. And just in front of that area

here is a region that we call Broca's

area or Broca's region. It's always been

thought to be a language specific

region. It is activated when we speak.

But interestingly,

it is also activated when a deaf signer

signs their language. Doesn't seem to

matter if you're vocalizing or

gesturing. It likes syntax.

Brocker's region is also activated when

we carry out any sequential syntactic

tasks with our hands

as part of an investigation into the

evolution of our brains. Nada

co-authored a huge study of volunteers

who did a 100 hours of training in stone

napping. So one before they'd done any

flintnapping and one after almost 100

hours of flintnapping and we could see

activations in Brocker's area and

changes so developments in that area as

well.

>> It's fascinating is isn't it this

connection between language vocalization

and hand movements. I'm doing it now as

I talk. there is a connection and it's

the same part of the brain that's

controlling different actions I do with

my hands and the the the words that come

out of my mouth.

>> A lot of people's mouths will mimic what

their fingers are doing. For example, if

you were sewing and you had to thread a

needle exactly exactly going to purse

your lips when you've got a tight uh

space and you're going to maybe open

your lips more when you're grabbing

larger objects. This could possibly date

all the way back to just feeding

behavior. If you're going to pick up

something small,

>> you put it in. If you're picking up

something big, you need to open your

mouth wider. We also have this

evolutionary theory that we might have

been first speaking with our hands

before language moved to our mouths.

Only a small portion of the way we

communicate is actually through our

vocalizations. We're still communicating

a huge amount about what we think and

feel and intend through our facial

expressions, our body postures, and the

way we move.

>> So the theory is that carrying out

complex tasks like tool making helped

put in place the final bit of the brain

which will be needed for language.

Over the past 2 million years, our

ancestors brains tripled in size,

particularly in the advanced cognitive

areas such as the preffrontal cortex.

So why did this happen?

One compelling theory lies in the large

groups which hunter gatherer societies

formed and which we've inherited today.

It's known as the social brain theory

and it's something I'm about to explore

in a very personal way. I've been

working on these documentaries now for

nearly 20 years. I've worked with all

sorts of people. This is the first time

I'm working with someone I know very

well, my wife Julie. We've been together

for over 40 years. I was asked to bring

along either a good friend or my wife.

And uh I don't have any good friends.

>> Yeah, not really. You weren't completely

happy to come along.

>> It's not my kind of thing.

>> You're not a showoff like me, is that?

>> No, I'm not a show off like you. Not

many people are show off like you.

>> But anyway, I hope you know what you're

letting yourself in for this time.

>> Not really, but I might finally get to

find out what you do on these shoots.

>> We'll stay friendly and see what

happens.

>> Okay.

>> Okay.

>> Julie and I have been offered an unusual

opportunity. We've been invited to drop

in on a major 5-year exploration of a

unique aspect of the evolution of the

human brain.

Researchers from Nottingham Trent

University have taken over an entire

house.

Cameras have been placed everywhere.

And while we're here, every move will be

filmed from different angles. And the

footage will be analyzed by researchers

hidden away in a different room.

>> Are you ready to play a game together?

>> Yeah.

>> For months now, psychological and

behavioral tests have been carried out

here with 120 pairs of best friends or

couples.

>> The game that you're going to play is

called Lost on the Moon.

>> Lost on the Moon is a puzzle game.

>> Do we need this? Well, we've been asked

to put these items in order of

importance to help us survive on the

moon.

>> Why would we need a box of matches?

>> Because there's no atmosphere on the

moon. Can't

>> light a fire.

>> I'm going to be hungry. I'm saying I'm

going to feel peckish and thirsty.

>> Yeah, but it's not just about you, Jim.

>> Well, you're you'll probably what? A

snack.

>> What have you got?

>> I've got the pistols.

>> Oh, pistols.

>> What we going to shoot

>> you?

Apparently, we're going to need the

pistol because if we run out of food,

Julie's going to get hungry and she's

going to want to shoot me.

>> I'm not going to want to shoot you

because I might get hungry.

>> Just cuz you want to shoot me because

I'm getting on your nerves. Fine. As far

as we're concerned, this is all about,

you know, how can whether we can survive

on the moon until we're rescued, but

it's clearly about actually whether

we're cooperating.

>> We're quite good at that.

>> It might not seem like it all the time,

but we actually do manage to compromise

and and cooperate. What do you mean

doesn't seem like that?

>> Well, it just

>> Sorry, dear. While all this is

happening, our facial expressions are

being recorded and a team of

evolutionary psychologists are analyzing

our results. Then they call us for a

meeting.

So, we've been videoing you while you've

been doing all of these tasks and we've

been measuring your facial movement.

Whether you furrow your brow, whether

you raise your brow, whether you smile,

whether you wrinkle your nose,

>> if I look eyebrow raises,

>> eyebrow raises.

>> So, this gives us a huge amount of very

detailed information of behavioral

information that's happening during a

normal conversation. Jim has a rate of

approximately 127 muscle movements per

minute.

>> Is that good?

>> That's very high.

>> That's quite high. Yeah, the average is

about 100.

>> Julie had slightly less facial movements

than me, but it might be because she

tends to play her cards close to her

chest.

>> Might just be one of those really dead

pan people.

>> The poker face.

This project is investigating how much

we use our facial expressions to bond

with others, especially our nearest and

dearest, and comparing it with other

primates.

>> Many primates have facial expressions

that are similar to ours, but our faces

are the most expressive. And we think

this sort of complexity is is probably

really important to humans as a species

and how we manage these really

>> complex intense social interactions we

have with other people.

>> That's helped the evolution of our

brains. The fact that we are able to

communicate with facial expressions.

>> That's the basic idea behind the social

brain theory that what is difficult um

is the social stuff. So forming

relationships, understanding the signals

of others, understanding the

relationships between other individuals,

maintaining your own relationships,

that's the stuff that's difficult to do,

and that requires big brains.

>> Proponents of the social brain theory

believe there's a direct link between

the relative intelligence of primates

and the social groups they can sustain.

As our ancestors spread out across the

lands, they formed bigger social groups.

This helped keep them safe from

predators, but took more brain power.

Living in groups has costs, but it also

has lots of advantages in terms of

access to mates. You can monopolize

resources, and primates are very good at

living in groups. I think it's important

to think about humans and what we're

good at. And what we're good at is

intense social interaction.

For this program, we decided to conduct

a little test on the social brain

theory.

And what could be more appropriate than

a good old traditional British pub quiz?

[Music]

I've invited Professor Robin Dumbar to

take part.

>> What are we having? A whiskey, Jimmy,

whiskey?

>> It's a long evening.

>> He's the person who came up with the

social brain theory after years studying

primates.

I start with some easy questions. The

greatest science communicator of all

time is widely acknowledged to be A.

Carl Sean, B Neil Degrass Tyson, C.

Brian Cox, or D Jamal Khalili.

I set the questions. By the way,

according to the social brain theory,

what is the number of meaningful

friendships which the average human

being is capable of maintaining?

It's 150.

In fact, that's a very famous number,

the Dunbar number.

[Music]

The Dumbar number sets limits to the

number of friends and family we're

cognitively capable of having proper

relationships with. The Dumbar number

you have reflects the cognitive demands

of managing relationships.

In fact, it's a concentric circle of

numbers starting with your closest

circle of five people, the people you

think about most and feel most empathy

for.

>> The single best predictor of your mental

health uh and well-being, your physical

health and well-being, even how long

you're going to live into the future

from today. It's simply the number and

quality of close friendships.

An average of 50 people are good friends

and 150 is the average limit for

meaningful friendships.

>> Beyond the 150, there's a layer that

goes out to about 500 of acquaintances.

You may spend quite a lot of time

chatting them, but you probably not

going to invite them home.

>> Robin says many studies show this. From

the average size of a medieval village,

150, to a huge study about the number of

people we communicate with properly on

social media.

The average is 149.

I'm going to set our audience a

cognitive test which Robin believes

helps prove the social brain theory. See

if you can solve it yourself. Each card

has a number on one side and a color on

the other. If a card has an even number

on one side,

then on the other side it has to be

blue.

Which card or cards do you have to turn

over to find out if that statement is

true or not?

Now, if you find this difficult, don't

worry at all. Up to 90% of people can't

work it out.

>> I got it wrong.

>> It's because it's deliberately phrased

in a complicated and abstract way.

Here's the answer. To find out if that

statement is true, you'd have to turn

over two cards.

They are the number eight card and the

red card. How many people got that

right? Can I have a show of hands? Our

audience tonight did pretty well, but

the majority didn't get it.

>> Now, second test. Jane's going to put up

on one side the age of the person and on

the other side what they're drinking.

Beer

and lemonade.

Which card or cards do you have to turn

over to see if there are any underage

drinkers in your pub? This one just

feels so much easier.

To check if anyone is an underage

drinker, you just need to check the

16-year-old to see what they're drinking

and the beer drinker to see how old they

are. How many people got that right?

>> Yeah.

>> There you go. just about everyone. How

many people found the first test easier

than the second test?

No one. And that's the real point

because amazingly these two tests are

actually the same test of logic. The

beer is equivalent to the red and the

underage card, the 16, is equivalent to

the even card, the number eight. But we

humans nearly always find one much

harder than the other. Somehow phrasing

it in that way in terms of social

activities that we're familiar with in

everyday life

makes that logic test seem so much

easier. And yet, it's exactly the same.

The argument is that's because the brain

is attuned to constantly checking for

people who infringe on social rules.

So we didn't evolve as abstract logical

calculators. We evolved to work out each

other and to solve social problems and

police social rules such as spotting

underage drinkers.

[Music]

A rapidly developing field of

neuroscience is now making some

intriguing breakthroughs, revealing

where in our brains much of our social

processing takes place.

Professor Nancy Canwisher runs a

laboratory at MIT in Massachusetts.

>> This is a slice through the middle of

the brain here. So you see this is the

front of the head, that's the nose,

that's the back.

>> Thanks. She made a name for herself when

she tried to detect brain activity when

we look at each other.

>> Faces are one of the most important

kinds of visual stimula. They are the

first stimulus that an infant wants to

look at. And for social primates like

us, it's absolutely critical to be able

to perceive faces and all the rich

information they tell us about another

person. We popped people in the scanner,

me to start, uh, and I looked at

pictures of faces and pictures of

objects. And so the first time we did

this, I remember coming out of the

scanner and finding this little blob in

my brain and you could just see in the

time course of response in the

experiment a big peak during the times I

was looking at faces in these little

teeny bumps when I was looking at

objects and I just thought that's

amazing.

What Nancy had found is called the

fusififor face area a highly specialized

location in the brain.

So the fusform face area seems to be

involved both in detecting a face like

that thing I'm looking at that's a face

and in figuring out which face that is.

Is that Joe or Bob or Mary or Jay?

This is the scan of my own brain and

this is my fusififor face area

activated when I looked at videos of

faces.

Nancy and her colleagues have discovered

other specialized social areas of the

brain.

This network has recently been

discovered. It's called the dynamic

social pathway.

It helps us analyze and identify moving

people and faces, expressions, other

people's intentions and moods.

This area is activated when we look at

people's bodies.

We even have a spot of our brain called

the theory of mind area activated when

we think about what other people are

thinking.

>> You can think of all of this apparatus

as part of our social mind. This is how

we function in society. It's a very

tempting hypothesis to say, look, it

makes total sense for evolution to have

built this structure in us. We are

social primates. We care about each

other. We need to detect and recognize

each other to survive. And so it would

make sense for evolution to have crafted

a specialized face processing machine

and built it into a brain. But we have

to be careful.

>> This is still a fast developing field of

science. These social networks could

have developed in our infancy as we

became exposed to faces or they may be

part of our evolutionary inheritance.

What's known for sure is that our

ability to bond together as social

creatures starts very early.

>> I'm convinced he's already saying,

"Mama,

look at this."

>> Dr. Georgina Donati collaborates with

Jillian Forester in studying brain

evolution and development.

Recently, she's brought into the world

her own test subject, 4mon-old Elio.

>> Raspberry is is is a new skill, isn't

it?

Elio's social brain is already starting

to kick in.

>> He's become very vocal recently. He's

talking a lot. Although he does he when

other people are talking, he like he's

likes to listen. But I mean, there are

all of these incredible mechanisms that

we've developed. You know, they come out

screaming their heads off, which makes

us all kind of run to them immediately.

And then and then they develop smiles

and giggles and these things which keep

us there and keep us interacting with

them and creates this interaction which

the babies need to learn

>> and humans have evolved that

>> this is something that I think we're

continuing to to find out and explore.

>> How does this compare human babies with

other primates for example or indeed

other animals? One of the special

characteristics of us humans is that

we're born relatively early and

underdeveloped in comparison to other

gray apes. Gorillas, when they're born,

they they can grip onto their mums

better. They're not independent yet, but

but they're not quite as vulnerable as

our human babies. We've got a longer

developmental period, and it's made us

able to learn things more socially from

a very young age. Who's this?

[Music]

Who's that?

>> Of all the toys that he's been

introduced to, this gorilla is

definitely the one that makes him

happiest.

>> A long childhood gives us what's known

as high plasticity. Our brains can adapt

according to the different environments

we're in.

But it means our ancestors had to look

after a helpless infant for years in the

wild. It poses a huge question.

>> How did we survive?

>> Well, so as you'll know, being a parent,

>> it's a massive parental investment. With

modern humans, we've often got two

parents. And we also have extended

families that help raise these babies,

not just to be fed, but to be socially

engaged and to keep giving the stimulus

and the stimulation to the brain. You

know, our brains carry on developing

through adolescence, and we've we think

now that this is carrying on until we're

sort of in our mid20s. So potentially

providing these very nurturing

environments really just allows this

plasticity, this learning, this

flexibility to continue for longer and

longer.

>> So the lesson is without loving,

self-sacrificing parents and supportive

social communities, we'd never have

survived the rigors of the wild and

evolved the brains we have today.

The human brain has now started to build

machines which can surpass it in so many

ways. We humans have used our cognitive

powers to astonishing effect. From those

very early stone tools to devices like

this, a smartphone is basically a

pocket-siz supercomput capable of

processing vast amounts of information,

carrying out operations much more

quickly than our brains could ever do.

And today we're on the brink of a new

technological revolution. Artificial

intelligence is already performing

complex mental tasks from essay writing

to composing music.

The future of AI, our most extraordinary

creation, is still unknown. But what

I've learned on my journey has given me

hope. that being in a community with

others was the crucial final step in the

evolution of our brains.

What has fundamentally shaped our brains

is our relationships with each other.

It's the family and friendship groups we

form. It's our shared histories, our

shared cultures, our beliefs, our

memories. Ultimately, it's our capacity

for empathy, for love, for

self-sacrifice, for thinking about each

other that has made us who we are.

Curious about how MRI technology can

reveal the secrets of your brain? To

watch the Open University's new

animation exploring how an MRI works and

what it reveals, scan the QR code or go

to bbc.co.uk. uk/secsofthebrain

and follow the links to the open

university.

[Music]