Original subtitles

(gentle music)

The Jura Mountains on the French/Swiss border

are in the grip of winter.

The ground has been frozen solid for months.

This is a tough place in which to live.

I'm told that clearings like these

could be the home of a real giant.

At this time of the year, it'll be in hiding.

But evidence of its existence,

these strange mounds, is everywhere.

Inside here, deep down and protected from the cold,

the giant is asleep.

Beneath the thatch of spruce needles lies a maze

of tunnels and chambers,

the home of hibernating wood ants.

Individually they are tiny, but they're members

of a giant super colony.

When temperatures rise, over half a billion of them

will emerge and dominate this landscape.

(intense music)

Scientists are only just working out how ants

manage to survive up here.

But in fact, there's a much greater and more profound

mystery that has brought me up this mountain.

Among ants, cooperation between colonies is very rare.

Warfare is common.

Yet these nests over a great area

live at peace with one another.

This may sound like an epic tale of war and peace,

but does it also contain an echo of human nature?

These ants in some extraordinary way

have exchanged war for peace.

It's not recognized as one of the largest

of all insect super societies.

And its very existence conflicts

with some of the laws of evolution

as we presently understand them.

(grandiose orchestral music)

It's been a long, cold winter

here in the Swiss Jura Mountains.

It's hard to believe that any insect

could survive in this frozen landscape.

But now change is in the air.

Soon ant nests all over this mountain will come to life.

Some of these mounds are independent colonies,

but others are part of one huge super colony.

Over the coming months, I'll be looking at the differences

between these two wood ant societies,

one that wages war with all its neighbors,

and the other, which welcomes them and lives at peace.

(gentle music)

As the grip of winter eases,

sentries emerge from the mounds to check on conditions.

They detect the sign that they've been waiting for.

The temperatures are rising.

Spring is on the way.

The ants survive the winter

thanks to their own central heating system,

warmth given off by the slow decomposition

of the dead vegetation in the nest's fabric.

And that prevents them all from freezing.

Now by swarming all over the surface of the nest,

they're recharging their batteries, absorbing heat

directly from the sun's rays.

(gentle orchestral music)

This behavior only happens over one or two days

in the early spring.

The worker ants have emerged into the sunshine

and are now clumping together.

And they're not just sunbathing, it could well be

that the ultraviolet rays of the sun

cure them of any infections from viruses or fungi

that may have happened during their long sleep underground.

You can almost feel the enthusiasm with which

these little creatures are enjoying their sunbathe.

(gentle piano music)

This is unusual enough, but now here is something

truly extraordinary, there is a queen.

She's almost twice the size of her subjects.

She's also the most important member of her family.

And what's more, there's another.

To see a queen exposed and vulnerable outside the nest

is very rare indeed.

There's one.

And there's another.

Shining wonderfully in the sunshine.

A normal wood ant nest usually has just a single queen

who lays all the eggs, but clearly,

this is not so here.

There's another, there's another, several of them.

Amazing.

(gentle orchestral music)

After a few moments in the sunshine,

the only time they see daylight in the whole year,

the queens disappear and make their way

back to the brood chambers deep in the nest.

(slow orchestral music)

Those unwilling to go are dragged back.

We may call them queens, but there's no sovereign rule here.

The workers govern by consensus, and they decide

when and where the queens will go.

There may be hundreds of queens in this single nest.

And there are over a thousand such mounds

as this all interconnected.

So across the super colony,

there may be as many as a million queens.

(gentle music)

It's now only April.

The queens, returned below to prepare for the egg-laying,

started a race against the clock.

They must complete their most important work below

in the next two months.

(gentle piano music)

Using infrared light, which is invisible to the ants,

we can watch them inside their nest without disturbing them.

Most of the first eggs to be laid will produce

the next generation of breeding individuals,

the queens and the males, both of whom will have wings.

Inside the thousand nests of the super colony,

over half a billion mostly unrelated worker ants

cooperate to ensure that the queens and the males

will be ready for their mating flights in mid-June.

(birds chirping)

With all these developments on the way,

it's imperative that the workers collect more food

as soon as possible.

But many of the mounds are still surrounded by snow,

so the workers can't reach their feeding grounds.

But there's something they can collect.

Heat.

The nest needs more heat than that which comes

from the rotting vegetation

if the eggs are to hatch in time for their June appointment.

Now, however, the ants have another source of warmth.

(playful orchestral music)

Using their bodies as solar panels,

the ants harvest the sunlight.

We have a heat-sensitive camera

that detects differences in temperature.

The nest appears black because it's hotter

than the surrounding environment.

It shows a similar difference in the ants.

Those going down into the nest are black

because they've been heated by the sun,

whereas those coming out are white

because they're cold, having transferred their body heat

to their charges in the brood chambers below.

It's this kind of selfless collaboration

that is the key to success of any ant colony.

In normal ant colonies,

all the workers are related to one another and the queen.

And the theory is that that is why they all cooperate.

But that is not the case here.

There are hundreds of queens here.

Over a thousand have been counted in a single nest.

So all the workers can't have the same parents

and genetics have confirmed that this is so.

It's this cooperation between unrelated ants

in a single colony that appears to be rewriting

the rules of insect evolution.

But we still don't really know how this has come about.

(mellow piano music)

Spring is now well on the way.

The snow has disappeared and color comes to the meadows.

(mellow piano music)

By late April, there are piles of eggs in the nest,

and the first larvae are hatching.

The workers labor unceasingly to ensure

that the growing brood will be ready to emerge

in six weeks' time at the peak of the short Jura summer.

(gentle orchestral music)

But not every ant nest on this mountain can be so focused.

Some will soon have to deal with threats

to their very survival.

Just a short distance away on the borders

of the super colony's woodland territory,

there are other wood ants.

The mounds here on this side of the mountain

look exactly the same as those of the super colony.

And so do the ants themselves.

The inhabitants of each nest here

are all the offspring of its single queen.

And the colonists compete aggressively with one another.

After the winter hibernation, the territories between

that nest over there and this one here

have become blurred, and the frontier

has to be reestablished.

And in order to do that, workers from both nests

are now scouring the ground.

And that brings neighboring ants into contact

for the first time this season.

(intense music)

When foragers from the different nests meet,

they immediately recognize that they're from rival families.

They then dash back to their nests, and within minutes,

both colonies know that territory on their frontier

is being disputed.

Armies assemble.

(intense orchestral music)

This is war.

And the weapons being used are chemical.

Formic acid.

(sniffs)

I can smell it in the air.

They're squirting it from the ends of their abdomen.

And if they can bite their opponents

so that the formic acids gets beneath the outer shell

of an ant, it will dissolve its internal organs.

(intense orchestral music)

As they grapple, each tries to restrain its opponent

by clamping its jaws around a leg or an antenna.

(intense orchestral music)

Soldiers from both sides tug at their opponents' limbs.

It could take seven ants to subdue a single enemy.

One holds each leg,

and the seventh uses its mandibles

to cut open sections of their opponent's

exoskeleton, exposing the insides.

An attacker brings forward its abdomen under its body

and squirts acid onto its victim.

Battles are going on everywhere.

Each colony carries its own chemical badge.

Invisible to our eyes, but clear

to the ants' sensitive antennae.

Fighters touch each other to confirm whose side they're on.

Here and there, individuals clamber up the vegetation.

Are they having a rest?

Or are they surveying progress to see where help is needed?

(intense orchestral music)

The smell of formic acid reaches the colony

and more ants from both sides run to join the battle.

(slow percussion music)

These wars can continue for over a week.

At their peak, many thousands are fighting

and thousands are killed.

(intense orchestral music)

The victors will certainly have enlarged their territory.

But some say they have also gained other rewards.

They're taking off the bodies of their victims

and carrying them back to the nest over there

to feast upon them.

Both sides have suffered heavy losses.

For the ants in the meadow,

it has been a costly start to the year.

(somber music)

Higher up the mountain in the territory of the super colony,

the inhabitants of different nests are also meeting.

But here, things are very different.

These ants come from a mound about half a mile away.

If that mound was a separate independent colony,

then these, when they land there,

will be savagely attacked.

But let's see what happens.

At first the resident ant makes an aggressive gesture.

But then the other strokes the first's antennae.

That gesture is a request for food,

and the other obligingly feeds her.

This behavior, known as trophallaxis,

is in itself not unusual.

Most ants do it at times.

What is unique is that these ants

are almost certainly unrelated, yet they treat each other

as if they were from the same nest.

They do this because they share the super colony's scent,

the chemical signature that is transferred

together with the food.

In one experiment, scientists fed a distinctive chemical

to a nest on one side of the super colony,

and eight weeks later, that same chemical appeared

far away on the other side.

It's this sharing of food between over

half a billion individuals that makes

this super society so truly remarkable.

(gentle orchestral music)

Because of this, super colony ants

can move freely between mounds.

And they have as a result created over a hundred kilometers

of trails that link over a thousand nests.

These trails not only allow the ants to make new nests

deep in the forest, they also give all the members

of the super colony access to resources

of great value to them.

It comes from the spruce trees.

(gentle piano music)

The ants don't feed directly on the spruce trees,

they become farmers, and these

are their flocks, aphids.

The presence of the ants keeps insect predators at bay

so the aphids can feed unmolested.

They drink the trees' sap and excrete what they don't need

as a sugary liquid called honeydew,

and the ants love it.

(gentle orchestral music)

Just as human farmers milk their cows,

so the ants stroke the aphids with their antennae

to persuade them to release their honeydew.

(bright orchestral music)

Once the aphids have milked and the ants have drunk

as much honeydew as they can carry,

they head down the tree, abdomens bulging,

and return to the nest.

(bright orchestral music)

The honeydew is not only food with which

to sustain themselves, some use it to raise the heat

of their bodies well above normal,

and as so, warm the atmosphere within the nest.

A valuable ability in the fickle climate of the Jura.

The spruce trees themselves also produce a substance

that the ants can use directly.

These ants

have collected little flakes of resin.

That's a sort of gum that oozes

from the broken twig of a coniferous tree.

The tree uses it to seal off an injury.

But what are the ants using it for?

Inside the nest, the extra warmth produced by honeydew

helps the queens to keep laying

and the larvae to keep growing.

However, constant warmth can create problems.

Despite regular cleaning, diseases can thrive.

The ants have a remarkable solution to that problem.

They cover the surface of the mounds with tiny nuggets

of resin, and also take it into the chambers below.

One nest contained over four kilos of it.

It is in fact ant medicine.

The ants combine acid from their bodies with the resin

and so produce a very effective antibiotic.

This is one of the most sophisticated

animal pharmacologies known to science.

It's been shown that wood ants living in nests

that contain resin are better able to survive

diseases than those that don't.

And their eggs are far less likely

to be infected by fungi.

(birds chirping)

This immense peaceful super colony has few enemies.

But now at the end of May, a new threat has arrived.

(cowbells ringing)

(cows mooing)

The Jura is famous for producing

some of Europe's finest cheese.

For generations, farmers have made small clearings

in the woods to create meadows where cattle can graze.

Only now is it warm enough for cows

to be brought up to these high pastures.

Somehow, the ants need to make sure that they're left alone

and that nothing damages their nests.

And that's a considerable challenge even for a super colony.

(intense orchestral music)

But these ants are very determined.

When one squirts its acid, others follow suit.

(intense orchestral music)

The result is a coordinated barrage.

(intense orchestral music)

The cows are not harmed, but they do get a dose

of acid in the nose, which they don't like,

and they tend thereafter to avoid these mounds.

(cowbells ringing)

By now, in June, the larvae have become big and greedy.

They must be given special care

because they will produce the next generation of royalty.

So the workers labor hard to meet their demands.

In summer, hundreds of thousands of eggs

are hatching every day,

and honeydew is not enough.

The ants go in search of something else,

a supplement, fresh meat.

(bee buzzing)

The lush green hills and mountains of the Jura

are now teeming with all sorts of life.

And nearly all of it is potential food.

(gentle music)

The ants spread out from the nest,

scouring every square inch of the ground in search of prey.

(gentle music)

As the hunters approach, those that can, take flight.

The ants' vision is not very acute.

They can only see a target if it moves.

A wolf spider, however, can see the ants clearly.

But as long as she doesn't move,

they won't know that she's here.

(slow orchestral music)

She's carrying a little sac full of eggs.

(gentle music)

She decides to run for it,

and her sudden movement alerts the hunters.

(dramatic music)

That first freaky touch by an ant left a faint scent mark,

and now fellow hunters can home in on their target.

The spider has a venomous bite,

but that is no use now.

Eight powerful legs are her only hope.

But her speed is the very thing

that enables the ants to follow her.

Slow motion reveals the basic ant-hunting technique,

lunge with jaws open and hope for the best.

(intense orchestral music)

At last an ant manages to grab her.

(intense orchestral music)

Like a pride of lions taking down a buffalo,

the ants surround her.

Two restrain their catch

while another delivers the fresh dissolving acid.

(intense orchestral music)

The wolf spider is just one of many victims.

(slow percussion music)

Alone, an ant can take only the smallest prey.

But by working as a team,

they can capture creatures many times their size.

(slow percussion music)

A super colony can make hundreds of millions

of kills every year.

Beetles, caterpillars, worms, flies.

They will tackle almost any living thing.

(dramatic orchestral music)

Whatever the prey, it's first cut up

and eaten by the workers, who then regurgitate it

to feed to the larvae.

Once they have grown to full size,

the larvae spin silk cocoons for themselves.

Inside each, a featureless larva is changing into an adult.

Their time in the sun is approaching.

(birds chirping)

Wood ants live in one of the most highly organized

and complex of insect societies.

They fight wars over territory,

they hunt in packs, and farm other species.

They build complex homes with central heating.

They produce their own medicine.

And one group of them we now know

has made another advance.

The super colony has extended this collaboration

beyond the frontiers of the family

to form a super society of such dimensions

that we can perhaps begin to compare it

with that other great social creature

on this planet, ourselves.

People studying the origins of human culture

suggest that shared myths were one of the factors

that bound early human societies together.

But what about ants?

Well, in many species, it is certainly the case

that all the individuals are very closely related

to one another, but that is not so

in the super colony.

And in some days in June,

such colonies continue to break the rules.

(gentle orchestral music)

As midsummer approaches, the Jura briefly becomes

a paradise of wildflowers.

And something new appears inside each of the nests.

Wings.

The royal generation, male and female,

has finally hatched, and both will be able to fly.

Winged individuals are the only ones

that are capable of breeding.

The males are little more than animated insemination devices

and they will soon achieve their purpose and die.

But the females, which are emerging just now,

this is the beginning of a long life of servitude.

(gentle music)

When the weather is just right,

sunny and not too windy,

the nests suddenly become covered with winged ants.

There's an excitement in the air.

(gentle music)

The males, which have matte black bodies,

are incapable of feeding themselves.

So once they leave the nest,

they only have a short time to live.

There's no time to waste.

The virgin queens who are also black

but splendidly shiny, have a rather clumsy

beginning to their lives.

They're heavy with fat reserves and swollen ovaries

so that getting airborne is not easy for them.

This is the most important flight of their lives,

but it's also their first.

Many test their wings before takeoff.

They may need several attempts before they achieve

complete flight control.

(bright orchestral music)

Over a few days, half a million winged ants

of both sexes take to the air

and head off for new territory.

(bright orchestral music)

They then all assemble here

in the heart of the super colony.

It's not clear how they find this meadow.

But year after year, virgin males and females

from across the super colony are drawn here

for their nuptial flight.

(bright orchestral music)

The queens congregate in small patches of taller plants

and begin to release sex pheromones,

airborne chemicals that attract males.

(bright orchestral music)

Detecting this scent on the wind,

the males home in on the females.

(bright orchestral music)

The virgin queens may only get the chance to mate once,

and they need to obtain enough sperm to fertilize

the eggs they will be producing for years to come.

But with plenty of males in the meadow,

they can afford to be choosy.

The males are so driven, they even try to mate with females

who are already doing so.

(bright orchestral music)

Those males fortunate enough to couple quickly

make the most of their few remaining hours of life.

Once they've mated, their service to the colony is over

and they die of exhaustion.

(slow orchestral music)

The queens now have no further use for their wings

and they try to get rid of them.

But they are necessarily rather firmly fixed.

(playful orchestral music)

Trying to remove a backpack with your feet,

even if you have six of them,

is clearly a frustrating process.

(bright orchestral music)

Eventually the meadow is marked with little drifts

of discarded wings.

Such breeding swarms are fairly typical of ants generally,

but now the queens of the super colony

do something much less common.

To understand why they behave so differently,

we must first return to the spring battlefields

of the ordinary wood ants outside the empire

of the super colony.

The warring colonies on this side of the mountain

have now accepted their frontiers,

and summer brings a brief pause in their battles.

The mating system they use may seem at first sight

to be the same as that of the super colony,

but in fact, it's fundamentally different.

Every decision taken by a mated female

is fraught with danger.

The colony this queen comes from

is at war with all its neighbors.

So if she meets any of them, they will try to kill her.

She needs a home, but she can't build it without help.

Her solution to the problem is extraordinary and radical.

Under this rock, a different species, field ants,

have built a nest.

These small ants, less than a third of her size,

are common and live in meadows on the edge of the forest.

The only way this wood ant queen can get her own nest

is by taking over one of theirs.

She will become a parasitic queen.

She lurks near the nest,

trying to pick up the scent of the field ants.

She avoids groups of them because they could overpower her.

Instead, she tackles individuals.

There's a brief duel, and then she retreats.

But each time she's left with a trace of their scent

so that she slowly begins to build up a chemical disguise.

These contests go on for several days.

Gradually her disguise becomes more and more convincing.

The entrance to the field ants' nest is unguarded.

Cautiously she enters.

Inside, she is vastly outnumbered.

Wood ant behavior inside a field ant nest

has never been observed in detail before,

let alone filmed, so what happens next

must be interpreted with caution.

(intense music)

There are fights, and most wood ant queens

are in fact killed at this stage.

But after she has endured repeated attacks,

some of the field ants become less aggressive towards her.

Eventually a confused field ant worker

feeds the wood ant queen.

And when it does that, the fate of the nest is sealed.

The wood ant queen has now acquired the colony's scent.

She oozes queenly pheromones, and the field ants

seem entranced by their new foreign queen.

The gamble has paid off, and she has a fully functioning

nest ready to receive her first batch of eggs.

Taking over a nest of field ants is the way

typical wood ants start a new family.

But how about the queens from a super colony

with their multifamily communal nests?

Have they found a more peaceful strategy?

Each mated female has to set out on her own journey.

If she's to become a true queen,

she has to find a nest that will accept her.

And that is where the tolerance of the members

of the super colony is tested once again.

Being already in the heart of a super colony,

these newly mated queens don't have to walk far

before encountering their own kind.

But even for a super colony queen,

walking straight up to a busy trail is risky.

If the workers she meets are not in a welcoming mood,

they will tear her to pieces.

(deep orchestral music)

Slowly, one by one, workers come to investigate her.

Some seem uncertain whether to attack or not.

But others lick and clean her.

(slow orchestral music)

After a few tense moments, a worker starts to drag her

towards the nest.

This is a sign that she will be adopted.

And now scientists have made a further discovery.

Many nests in the super colony shortcut the whole process.

The winged males and the queen ants

don't even bother to leave the nest.

Many different families live here,

so there's no need to fly away to avoid inbreeding.

The winged queens can simply mate

with one of the males that hatched here.

Perhaps this unusual behavior is the next stage

in the evolution of the super colony.

With these innovative mating systems,

the super colony queens don't take the same risks

as normal wood ant queens.

They don't need to infiltrate the nest

of field ants to start a family.

The workers just build new nests when needed,

enabling the super colony to extend deep into the forest

where there are no field ants.

It's changes in behavior like this

that most likely gave rise to the super colony

in the first place and colonized this new habitat

with all its riches.

(grandiose orchestral music)

It's possible that this kind of cooperation

between different nests is becoming more common among ants.

New super colonies are still being discovered

in different species across the world.

Are we perhaps witnessing the next stage

of the social conquest of the Earth?

The super colony consists of literally thousands

of different families all working in cooperation.

It's a development that mankind achieved

a very long time ago and could be seen

as one of the reasons why we have come to dominate

so many parts of the planet.

Could it be that peace is the winning strategy

on this ant mountain, too?

(grandiose orchestral music)