Great Apes The Wonder of Animals

Planet Earth.

Millions of different species.

But a few are special.

Born to thrive.

These are the opportunists.

The collaborators.

The survivors.

So, what is it that makes these animals so successful?

By exploring the details deep beneath the skin,

we'll discover the unique features that set some species apart.

In this series, new behaviour,

and the very latest scientific discoveries

will throw fresh insight

into the wonder of animals.

Humans may have the most complex brains on the planet...

..but we've got some relatives that aren't far behind.

The great apes.

In this episode, we'll reveal how different parts of their brains

have been adapted over time by their anatomy...

..their ingenuity...

..and their sociability.

These three forces have shaped the evolution

of one of the most intelligent groups of animals on the planet.

But our journey starts with the simplest of beginnings,

one part of their anatomy.

And that part

is the hand.

The great apes, orang-utans,

gorillas, chimpanzees

and, of course, us, all benefit by having a form of opposable thumb.

This is a thumb which is capable of moving

so it can touch the other digits on the hand,

but of course, the other great apes use them in different ways.

Gorillas spend most of their time on the ground.

They use their hands to select and manipulate their food.

In the trees, chimpanzees and orang-utans hold branches

with opposable toes, as well as thumbs.

What they all have in common is the ability to grasp objects...

..with a dexterity that few other species have.

And it's this dexterity that has allowed the primate brain

to really flex its muscles.

Delicate hand movements take concentration and control,

the more intricate the hand movement the more brain power is required.

And there are few movements more intricate than using a tool.

Chimps fish for termites with handmade rods.

Palm branches act as a pestle,

to soften the tree's edible heart.

And folded leaves make sponges for gathering water.

Orang-utans also use branches as tools...

..to get fruit that would otherwise be out of reach.

And those that live near humans

sometimes even try our tools.

These actions may look simple

but what's going on inside the apes' head is highly complex.

Many parts of the brain work together to create these movements,

but one part in particular is key.

The cerebellum.

This is the part of the brain that enables us

to move our limbs in an accurate and controlled way,

and recent research has found that it's crucial for tool use.

Over many generations,

those that learned how to use their hands survived better.

So, as the more dexterous individuals thrived,

gradually bigger brains evolved.

But there's a lot more to dexterity than just having an opposable thumb.

This chimp is doing something that a lot of animals can't.

Many animals can only use their hands symmetrically.

The great apes, however, can use their hands asymmetrically.

Both at the same time and in different ways.

For us, it's such an ordinary ability

that we simply take it for granted.

But asymmetrical bi-manuality, as it's known, is, in fact,

a complicated skill and it takes a lot of brain power.

Once again, the cerebellum is hard at work.

It's communicating via a huge number of connections

with another key part of the brain, the motor cortex.

This part controls the movement of the body's muscles

and in the great apes,

the largest area of the motor cortex is devoted to the hands.

All the great apes have evolved

an enlarged motor cortex and cerebellum

compared to other primates...

..allowing them to use both of their hands independently.

But whilst using tools takes dexterity,

actually designing them and building them

takes something altogether different,

ingenuity.

The orang-utans of North-West Sumatra feed mostly on fruit.

But when the swamp forests flood, the waters bring in rich nutrients

and in their wake, an abundance of insects,

a welcome break from their usual diet.

Although they are more difficult to collect.

The orang-utans, however, have come up with a solution.

They break off a branch,

strip off the twigs...

..fray one end...

..and then, dip the stick into holes in the trees,

to get honey and termites.

They've designed and built a makeshift spoon.

As well as constructing tools,

great apes devise strategies for using them.

A flurry of recent research

has revealed that chimpanzees actually plan ahead...

..collecting useful objects before they're needed

and then, taking these tool kits to the feeding site.

If they haven't got quite the right one for the job,

they use a sequence of up to five different objects

to get the tool they need.

This ability to problem solve

gives apes access to food that would otherwise be unobtainable.

Ingenuity and innovation exercise the brain.

Compared with less resourceful animals,

great apes have bigger, executive brains,

that's the neocortex, the top layer,

and the striatum, deep within.

Parts of the neocortex are crucial to innovation

as they inhibit old patterns of behaviour and generate new ones.

So, over time, devising ingenious ways to get food

favoured an expansion of the brain.

But apes aren't born intelligent.

Their brains have to be programmed with the right information.

They have to learn.

And they don't just learn by watching.

One research team from the University of Zurich,

believe they have evidence that apes actively teach their young.

In the tropical rainforests of the Ivory Coast,

an important food source is nuts.

Nuts are energy rich,

but only if you can crack the shell.

By numbering rocks,

scientists were able to analyse how the chimpanzees used them as tools.

This is the hammer,

and this is the anvil.

Adult chimps can crack open 130 nuts in an hour.

It takes ten years for the young chimps to fully acquire this skill.

The study found that when their young are present,

adults often leave their hammers by the anvil

whilst they're collecting nuts,

to give the infants a chance to have a go.

The scientists also observed mothers

showing their young how to position the nut correctly.

Acting for the benefit of others like this

is a crucial part of collaboration...

..the first step towards building a cohesive social group.

Most great apes live in communities.

In chimpanzees, these communities can number up to 150 individuals.

So, this means developing complex relationships.

They must learn who to greet...

..who to play with...

..and when to work together as a team.

All of which requires a bigger brain and once again,

many parts are at work.

But crucially, a tiny region called the amygdala.

Recent research has found

that primates living in large social groups have a bigger amygdala.

It's thought that this part of the brain may have evolved

to deal with an increasingly complex social life.

It's the same within humans.

The more complex a person's social network,

the greater the volume of the amygdala.

This part of the brain enables great apes

to form relationships and function as a team.

And at no time is collaboration more important in chimp society

than when it comes to a hunt.

Their prey, the colobus monkey,

is fast and light.

To catch it, the chimps must work together.

Certain members will herd the colobus...

..driving the monkeys into a trap...

..where a second group will make the kill.

COMMOTION

SCREECHING

But this controlled aggression

is not always directed at prey.

SCREECHING

Chimps can turn on each other.

If a territory is under threat from other communities,

the chimps will fight to protect it

and secure access to the best food.

But not all great apes are quite so aggressive.

There is a species that's followed the path of peace

and it all began one million years ago.

Back then, this central African land was occupied by two ape species.

The ancestor of modern-day chimpanzees...

..and gorillas, their ecological rivals.

Until...so as one theory goes,

a massive drought drove the gorillas away

from the south side of the River Congo.

The chimpanzee ancestors now had the southern jungles to themselves

with little competition for resources.

And with plenty of food to go round,

what's the point in fighting?

Over hundreds of thousands of years,

aggression gradually became a less prominent trait.

And those chimpanzee ancestors south of the Congo River

evolved into today's bonobo.

This evolutionary theory has been put forward

by scientists from America's Duke University,

And it may explain why the social behaviour of bonobos

is so different to that of chimpanzees.

Famous for their love of sex over war...

..bonobos seem to have replaced aggression with seduction

as a means of resolving conflict.

But their bonding instincts run far deeper than this.

Tests done by the scientists found that whilst chimpanzees

will fight over food...

..bonobos will actually share theirs.

Even with strangers.

So, how did this gentler trait evolve in bonobo society?

The Duke University anthropologists

have again possibly come up with an answer.

Could it be that bonobos have gone through

a process known as "self-domestication" -

a bit like the process that dogs have gone through

in their evolution from wolves?

Generation after generation of selectively breeding

for more passive dogs,

means that their wolf-like aggression has diminished.

Leaving them, just like the bonobos,

altogether more friendly.

But according to the theory, over hundreds of thousands of years,

some species are actually capable of domesticating themselves.

Like the bonobos.

So, a million years ago,

on the south side of the Congo River,

as the ancestor chimpanzees enjoyed a land of plenty,

there was less call for violence.

And therefore, the females were able to choose

to breed with less aggressive males.

In this way, over many generations,

the bonobos domesticated themselves...

..becoming a more gentle species of ape.

But even more remarkably,

they now show a trait that was once believed to be uniquely human.

This orphan bonobo is playing with his friend,

but it soon gets rough.

The mother of the victim intervenes

and reprimands the orphan by biting his finger,

whilst another mother tries to stop her.

What's remarkable is how the rest of the group

react to the injured orphan.

They show empathy.

Two young bonobos come to see how the orphan is.

Empathetic behaviour of this kind

is regularly observed in bonobos.

Empathy is a complex emotion.

The fact that bonobos are capable of it

proves that their reduced aggression is more than skin deep.

It's down to a difference in their brains.

Scientists from Emory University in Atlanta,

have found that parts of the brain crucial to feeling empathy

and regulating emotion, the limbic structures,

are more developed in bonobos than in chimpanzees.

In bonobos, these areas contain more grey matter

and have a thicker connection between the amygdala

and the anterior cingulate which helps moderate social behaviour.

When the bonobos sense that their actions are causing distress,

that pathway works to reduce their aggressive behaviour.

What's remarkable about bonobos' empathy is their ability

to show compassion to strangers, as well as to others in their group.

As one of our closest living relatives,

researchers are now investigating to see if there are similarities

between the social tolerance of bonobos and that of humans.

What's certain is that bonobos have crossed an imaginary line

that was once thought to separate us from our ape relatives.

The ability to feel and respond to the emotions of others.

The great apes' anatomy has enabled them

to use their hands with exquisite precision.

They've developed ingenious strategies for designing tools,

which have kept their big brains fed.

In turn, allowing them to navigate the complex relationships

that come from living in a society.

Dexterity, ingenuity and sociability

have all played their part in the evolution

of one of the most complex brains in the animal kingdom

and that is the wonder of great apes.