Original subtitles

'We are about to embark on an ambitious project.

'Something that's never been tried before.

'It will show us a hidden world.'

I'm standing in the middle of something

that you would never normally see.

It's taken six months from planning to this.

A new home for one million

of nature's most extraordinary creatures.

Ants.

'They fascinate us. They build complex, organised societies.

'And we've always drawn parallels between the world and ours.'

It's basically an ant production line.

'So what can we learn from ants?'

One ant in two million, and we found her. Fantastic.

To find out, we've brought a working colony of leafcutter ants

from the tropics of Central America.

We've recreated their nest so that we can see inside.

And for one month, we're going to capture every aspect of their lives.

'We'll track them.'

This is going to be great, because this is going to tell us

what these soldiers are doing in the ground.

'We'll listen to them.'

That little chirp?

Yeah.

'And get right up close to them.'

One's gone down my front!

'We'll go beyond our own ant metropolis

'to meet some of the most impressive ants on the planet.'

It's not just a group of ants holding on to each other,

it's a survival raft.

It is. It's a force to be reckoned with.

'And discover the surprising ways in which ants

'are helping us solve global problems.

'I'm an entomologist, and even to me,

'what ants can achieve is astonishing.'

'Our project will show their world as it's never been seen before,

'and reveal what they can teach us about ourselves.'

Glasgow. Not the natural home for leafcutter ants.

But over four weeks,

the Science Centre here will play host to our ambitious project.

Our goal, to unlock the secrets of the ant colony.

Well, the stage is now set for our remarkable experiment.

It's hot and humid in here,

and everything you see here is based on real-life.

Well, this is normally all you'd see of a leafcutter ant colony,

the bit above ground - ants taking bits of leaf underground.

Now, like an iceberg, the main event isn't the bit you can see,

it's what's happening beneath, and that's a part of the ant colony

that even scientists like me rarely ever see.

In the wild, the leafcutters dig huge underground nests.

We've used their natural design to inspire our own creation.

Down below here, underground,

we've tried to recreate what an ant colony would look like.

These boxes represent chambers in the soil, and the walkways are tunnels

in the soil by which the ants can access all parts of the colony.

'But the leafcutters need more than just a nest. They also need to feed.'

'We've built them a whole environment where they'll be able to search

'or forage for food as they would do in the wild.'

We've got plants in certain areas joined up to a main foraging area

with these rope walkways.

Now, in the real world, in the natural habitat,

these would be creepers and other plans.

Now, as you can see, there are no ants on it yet, but there will be.

In a short while, we'll let the ants loose

over this whole new world we've built for them.

And over the next month, I'm going to be really interested to see

how they take control of it and how the colony develops.

'Joining me is Professor Adam Hart

'from the University of Gloucestershire.

'He's studied the leafcutters for over 15 years.

'He's helped design a series of experiments

'to uncover how the colony works.

'And the first thing he's going to do

'is help us see inside one of the boxes.'

Adam, what's happening inside the box?

Hundreds of ants are attacking this camera!

Let's just try and wiggle it around a bit.

Now that box is absolutely swarming with ants,

and they don't seem terribly happy with your camera in there.

No.

'This is my first glimpse into the hidden world of our ant nest.

'In the wild, this would be an underground chamber,

'excavated by the ants themselves.

'And inside here is something vital to the colony.'

This grey material here is fungus, in fact,

which they're farming inside the nests.

They're using those leaves that they cut to help them grow this fungus.

'Leafcutter ants, despite their name, don't eat leaves.

'They bring them into the nest as a food supply for this fungus,

'and it's the fungus that they eat.

'Our ants are farmers, and the fungus is their crop.'

This means I can see right into the nest,

I can see the fine details of their normally hidden lives.

This is just incredible.

'In among the fungus, the white,

'translucent shapes you can see are the brood.

'That's the young of the colony, the eggs, larvae and pupae.'

'Here we can see the adults attacking the camera,

'whilst in the background, the brood is whisked away to safety.

'All that brood, every single egg, is laid by one ant - the queen.

'She's hidden somewhere deep within the nest,

'and hopefully we'll be able to track her down later.

'Right now, I want to open up this box and get my hands on some ants.'

Let me just get a bit out. I'll try and avoid getting a big soldier.

Try and avoid a soldier, yeah, I wouldn't like that very much.

'The soldiers, as the name suggests, are ants who protect the nest.

'They're big, and they bite.'

I haven't managed to avoid a soldier.

Haven't you? Oh, thanks. Oh, it just bit me! Thank you.

There's a big one there. Yeah, a big one.

One of them has just bitten my hand. Ah!

Wow.

There is a massive soldier -

ow! - who has just found a crease in my skin,

has sunk her jaws right into my skin, that's actually quite painful.

Yeah.

Now, you can see why the soldiers are so good at defending the colony.

Adam, I think I've had enough of holding this.

Shall we put it back?

Yes, if you could scoop that out.

'The soldiers are just one kind of ant in our leafcutter colony.'

Now, the first thing that is really obvious when you look at an ant

colony is that the adult ants seem to be of different sizes.

Now, it's not because they're not fully grown,

it's because they are different castes of ants,

and under here I've got three different castes of worker ant.

'In the insect world, a caste system means that individuals

'differ in shape and size within a single species.'

So you can see the range of size from the very, very small workers,

to the middle-sized workers, and the very large workers here.

And they're different sizes for a good reason.

Each of these castes of ants have a different job to do.

'I've already had a painful encounter with one of these, a soldier.

'That head isn't filled with a large brain,

'rather a massive set of muscles to power a fearsome pair of jaws,

'or mandibles, strong enough to cut through my skin.

'Going down the size scale,

'this smaller ant is called a media worker.

'These are the hands that collect and bring leaves back to the nest.

'It's serrated jaws are just the right shape

'for cutting into tough plant material.

'At the very bottom of the scale are the minima,

'the most numerous ants of all.

'These tiny nest mates effectively turn the leaves into fungus

'and tend to the brood.

'So the first thing we learn from our colony is that the labour

'is divided between all its members.

'Each caste of ant has a role to play.

'To allow us to investigate how all these different castes

'organise themselves and work together,

'we needed a supply of ants on an epic scale.

'Not just a handful bred in a laboratory,

'but a thriving, working colony from the wild.

'And Adam was giving the job of tracking one down.'

'I've come to Trinidad, just off the coast of Venezuela,

'and I'm on my way to a colony of leafcutter ants

'that sounds perfect for our project.'

Leafcutters are native here,

and they're considered a serious agricultural pest.

The colony we found was about to be destroyed by a farmer.

We want to rescue it and take it back to the UK.

'But digging up a nest of this scale won't be an easy task.'

They're huge.

There's tens of thousands of very aggressive soldiers

that will come out and bite you,

but we're going to have to do it almost surgically when we begin,

because we really need to make sure that we don't kill that queen.

The queen is the absolute critical thing in this colony.

We can get away with not bringing all the ants back,

but if we don't have the Queen intact, then we're stuck.

'Waiting at the nest site is Andrew Stevenson.'

All right, Andy? All right?

How's it going, good to see you.

This is the nest?

What do you think?

'Digging up ants is Andy's speciality.

'He provides leafcutter colonies to zoos, museums

'and universities all across Europe.'

I don't think it's too big for digging,

but what we're going to do is we're going to start at the bottom

with a trench, and then take sections as we go back through the

bank, hopefully showing a lot of the architecture of the nest as we go.

'At the moment, the only sign the leafcutters are even here

'is this loose pile of earth produced by the ants

'as they dig out their underground nest.

'This is because in the wild,

'our species of leafcutter tends to be nocturnal.'

'So to get a sense of how big the nest really is,

'we have to wait for night to fall.'

So here are leafcutters on the trail,

and you can really get a feel for their destructive power.

This is a fruit tree,

and the leaves are just pouring down out of the tree.

All of these fragments have been cut up, they're in the canopy,

and there are hundreds of ants passing every minute.

Just conveying, like a conveyor belt of leaves from the top of the tree,

all the way to the colony, which is about 100 metres away up the hill.

'It's easy to see why farmers are no friends of leafcutters.

'From the huge numbers of ants in the soil here,

'we reckon this colony is at least a million strong,

'so it's certainly on the scale that we need for the project.

'And so many ants means a large, subterranean nest.

'So to get a sense of how big a job we'll face on the dig tomorrow...'

Adam, over here, we've got one.

'..Andy and I are placing lights at each nest entrance we find.'

'This should show us roughly how big the nest is beneath our feet.'

What we've done is marked out what turned out to be

more or less a circle of lights.

It seems to show that most of the activity in this colony

is focused on the bank here,

where we're going to start doing our sectioning in the morning.

It's good news, because it means that once we get stuck into

that central part of the bank right in the middle of the lights,

we should start hitting fungus chambers quite quickly,

and with any luck, fingers crossed, we might even get the queen.

'It's the day of the dig,

'and time to see what the colony looks like underground.

'But the ants aren't about to take our intrusion lightly.'

This is pretty much the first blow of the spade,

we've been digging for about a minute, and already,

on the surface here, I can count

at least 20 or 30 of these big soldiers.

It's made our life a bit more difficult, in a way,

because we're now going to be under attack digging this trench.

'Undeterred by the threat of the soldiers,

'Andy and his team continue with the dig.'

Let's start taking about a foot at a time.

We'll start taking a slice and we'll work our way back.

'Before long, we've pushed back into the nest.

'What we see is a maze of chambers, connected by a system of tunnels.

'This natural architecture is what we've tried to

'recreate in building our own ant nest,

'with glass boxes and tubes replacing the chambers and tunnels.

'By mimicking a real-world design,

'we hope to encourage the ants to behave as they do in the wild.

'And it's not just the ants we need to rescue from this nest.

'The underground chambers are packed full of vital fungus.

'We need to collect as much of this fungus as we can.'

'Without it, the ants will quickly die.'

We've got into quite a good rhythm, now, really.

There's lots and lots of these fungus chambers

going back into the bank.

Every time you put the spade in and pull some soil off

it exposes some more,

so it's really just a case of methodically going through them,

when they fall out, or when you pull them out,

and making sure the queen's not there, so just keep cutting back,

keep cutting back, trying to find that queen.

'At the end of day one, we've recovered thousands of ants

'and a large quantity of fungus,

'but we've still to recover the most vital ant of all.'

No, she's not here.

'The queen.

'Failure to find her means failure of the entire project.

'Day two, and the hunt for the queen continues.

'We're searching for something quite distinctive.'

The queen is huge compared to other ants,

and she'll be covered in smaller ants, who tend her.

There's something really smart here.

Oh, yeah?

OK.

Yeah, yeah.

'This could be our needle in a haystack.'

This looks very promising.

So this could be the queen in the middle.

I think we're in, here.

Yes.

There she is. The queen, excellent.

One ant in two million, and we've found her.

'Through tons of earth,

'we managed to find the most important ant of all.

'It's a great relief to the whole team,

'and it means our project can go ahead.'

So this is what we've been seeking in all our mining.

This is the queen of the colony,

and I'm going to very carefully pick her up.

She is surrounded by a attendant workers who are biting me now - ow!

But she's in there.

That's the egg-laying machine that's at the heart of this colony.

And there she is, ready to go on her...

We're going to stick her onto a really nice use of fresh fungus,

very carefully, very gingerly, just plonk her on the top, there.

And that's..?

That's us.

That's us done. Good job.

'The race against time begins now.'

'We need to get the ants from here to the UK as quickly as possible.

'After two flights and a transatlantic journey

'of more than 4,000 miles,

'the ants arrive at their final destination,

'the Glasgow Science Centre, where their new home awaits.

'We put the ants and some fresh soil onto the top of the nest.

'This is our ground level.

'From here, they make their way down into the nest boxes,

'like the chambers we saw in the wild.

'And it's with some relief that we come across an old friend,

'the queen.'

Excellent.

'With the survival of the queen confirmed...'

Yep, she's in. OK.

'..and the ants exploring their new nest,

'the signs are good that our colony has survived the journey.

'Now we're hoping that they'll take over

'and complete the building of their new world.'

'We've given our ants time to settle into the main nest area.

'Now we're ready to let them loose

'on the wider world we've built for them.

'It's our first chance to see how they organise

'the great collective endeavour they're famous for.

'Leaf cutting.'

What we want to do now is to allow them to forage in a natural way,

they would do in the real environment, and to do that,

we need to join up the colony with the virgin foraging lands beyond.

'For the ants, it's finally time to explore.'

Well, we've only just put the bridge in, and already we've got workers

swarming up as far as here, so I don't think it will take very long

for them to find the other end of this bridge.

'Tentatively, the ants start to make their way down the bridge,

'although it's not exactly a massive trail yet.'

In the wild, you see them foraging all over the ground,

but how far will they forage from the main nest?

Up to 100 metres, sometimes more, so you can follow these trails

deep into the forest, and in fact, this colony was foraging deep into

a citrus grove, and you could follow them back for 100 metres or more.

'Our time-lapse cameras reveal that the trickle quickly becomes a flood.

'More and more ants head out to explore the foraging areas beyond.

'Now we'll have to wait to see how quickly they discover the plants

'and get their leaf-cutting operation under way.

'But there's one caste of ant we'll hardly ever see out here,

'and that's the soldiers.

'Unless they're responding to a threat,

'they tend to stay hidden deep within the nest.'

But we won't get a full picture of how our colony works

unless we can discover what these mysterious ants are doing.

So to find out, we've turned to technology.

'We're going to use radio tracking devices

'to follow individual soldiers 24 hours a day.

'Joining us to help is Clare Asher

'from the Zoological Society of London.'

So, what we're going to do is we're going to glue some radio frequency

tags onto their back, and Claire here is quite an expert at this.

I'm keeping well out of it, because I'm getting glued up myself.

So I just pop a little blob of glue.

Yeah.

On their back.

How heavy are these tags?

They hardly weigh anything at all, and to an ant like this,

they won't even really notice it.

There we go. It's fiddly work.

It is. You just need to...

And that should dry in a short time?

Very quickly, yeah.

I should point out that what we're doing isn't hurting

the soldier ants at all.

How long would they survive in the wild anyway?

These sorts of ants would only live a couple of months, often.

They're not long-lived.

This is going to be great,

because this is going to tell us what these soldiers

are doing, which we don't have a chance of finding out.

And where they are.

Yeah, and how much they move around, what they're getting up to,

which we know very little about, if anything, really.

So it is original research, this?

Yes.

Every tagged ant will emit a unique radio signal.

And to detect those signals,

we've placed radio receivers all over the nest.

This will allow us to track each individual ant

and follow its every movement.

We don't know what the ants are going to do,

or even if this experiment will work, but we're hoping it will give us

new insights into the role of the soldiers in the colony.

'While we've been busy, so have the foraging ants.'

Just look at that.

That's barely three hours

and already there's an incredibly well-established trail.

Yeah, it's teeming with ants.

We've got a really nice flow of ants going this way without leaves,

and these leaf-carrying ants going back to that big fungus garden

over there, so it's really, really nice.

Now, it seems to me that a few of these are a bit confused,

and some are going the wrong way.

Yeah, I think we've got a little bit of a pinch point here.

It's so busy going in this direction that I think some of these

ants are getting turned around, but that will even itself out.

Collectively, the ants carrying leaves are going in that direction,

and the ants not carrying leaves are going in that direction,

but there's always a few little errors.

I feel I want to help the ones that are heading the wrong way and just

go, "Come on," take you off and put you down there, bit of a head start.

'These ants are finely-tuned leaf-cutting machines.

'A large colony can consume the same weight of vegetation

'per day as a cow.

'And they're making short work of the plants we're giving them.'

It's fantastic to watch them at work, because if you just look at it,

glanced at it, it would just seem to be random, but it clearly isn't.

I don't know if you can see up close, George,

the way that they're actually cutting the leaf fragments.

It's really interesting. It's not how you might expect them to do it.

They're not using those mandibles like scissors.

The right-hand jaw is anchoring the leaf,

and the other one is a bit more like a guillotine.

Yeah, more like a blade going through.

'This method is incredibly powerful,

'enabling the ant to slice through even the toughest of leaves.'

Here we can see that same blade-like technique being used

on a very thick banana leaf.

They're anchoring themselves with the back feet, the back legs,

so when they go around with this guillotine, they're describing

an arc of a circle, and the bigger the ant, the bigger the arc.

Absolutely.

So you end up with a really nice mechanism to make sure that

bigger ants carry bigger loads.

Over the next few days,

our ants establish the leaf-cutting operation on an impressive scale.

A marching column across the ropes, over the foraging table

and up the bridge.

When they reach the top, the ants head down into the nest,

making their way through the tubes towards the fungus gardens.

There, smaller and smaller ants chop up the fragments

until it's mashed into a kind of plant mulch.

The tiniest ants of all then insert this mulch into the growing fungus.

There's nothing haphazard about this process.

The structure we see here is carefully built by the ants.

The pattern of ridges and hollows allows them

to fit more fungus into a confined space,

and the hollows provide a safe place to nurture the brood.

The whole process is like a massive production line.

It just looks like a conveyor belt of green material just disappearing.

It feels like the right sort of language to use.

We've got an industrial cutting process going on here.

We've got this conveyor belt going back to the processing, the factory,

if you like, back at the nest, so it's a real machine at work.

It's this kind of collective endeavour that has made ants

so fascinating to us humans down the ages.

During the Industrial Revolution, when factory life was

transforming human society, the parallels were striking.

Dr Charlotte Sleigh has studied how we viewed ants throughout history.

I think the 18th century is a period when you start seeing some really

sustained interest in ants and the way that they live, and a lot

of those very earliest writers were coming from a theological tradition.

Indeed, many of them were ordained clergyman.

The qualities that the ants exhibited

were considered to be really twofold.

One of them was industriousness, they worked, really, really hard,

and that's something everybody should do, and the other thing

that they exhibited was what the Victorians called mutual aid.

That is to say, they helped one another,

and supported one another in the life of the nest.

And as the Victorians travelled the world on the business of Empire,

they encountered new and intriguing species of ant.

One such traveller, an English engineer called Thomas Belt,

particularly admired the leafcutters.

Thomas Belt was a mining engineer,

and when he went out to Nicaragua, around about 1870,

he was not impressed with the native Nicaraguans,

he was not impressed with the Hispanic colonists,

he thought they had become sort of lazy and dependent

on the native labour, but what he really rated

were the leafcutter ants, and in particular,

he was so tremendously impressed with the mining that they did,

just like he was planning to, with the tunnels they constructed,

it was as though he had found the English in Nicaragua in the ants.

Watching our leafcutters at work,

it's easy to see why Thomas Belt was so impressed.

Their leaf cutting operation is a highly-sophisticated,

highly-organised collective endeavour.

This remarkable ability to cooperate isn't unique to the leafcutters.

Adam's been investigating on another species of ant

that takes the idea of cooperation to a whole new level.

Floating on the Amazon River is a wonder of the animal world.

It may look like a tangle of weeds, but up close,

it's a seething mass of ants.

This is Solenopsis invicta, the fire ant.

To survive the regular floods of the Amazon, an entire ant colony

can join together as one large raft, built from their own bodies.

They can survive like this for months, waiting for dry land.

So, how do the fire ants do it?

'I've come to Georgia Institute of Technology in America, to meet

'a scientist who's tried to discover the secrets of the fire ant raft.

'It's my first chance to see these extraordinary

'boat-builders up close.'

One of the big questions people ask is

what happens to the ants on the bottom.

Do they drown, and the answer is no.

They essentially remain dry,

even those bands that break through the surface tension of the water

and are fully submerged trap a layer of air around their bodies

so they can still breathe.

So there's an obvious thing for us to do now, which is to try

and submerge them and see what happens.

Can you push these down?

When you push it under the water,

they retain a pocket of air around their bodies.

It's almost encapsulating them inside an air pocket.

I can show you that here.

They're very buoyant.

They are. There we go.

So there's a silvery sheen over the outside,

which is all the air bubbles that have been trapped.

That's the air-water interface line, there.

Each ant is naturally water repellent.

Droplets simply slide off them.

And when thousands of ants combine,

the result is a raft that is virtually unsinkable.

When you do push them under the water, they pull themselves

even tighter together, so that when the subjected to the high

pressures underneath the water, it still keeps the water out.

Magnified hundreds of times,

the secrets of the fire ant raft are revealed.

The mandibles are used to grab hold of a nest-mate's leg.

At the end of each leg is an adhesive pad and a claw.

This, like a sticky grappling hook, allows them

to form further flexible connections with any nearby nest-mate.

The ants' own bodies act as a set of interlocking units,

so the entire colony can turn itself into a single structure.

So this is really an unsinkable, self-healing lifeboat?

It is. It is a force to be reckoned with, that's for sure.

This remarkable ability allows the fire ants to survive

the worst floods of the Amazon.

Cooperation has made them an engineering marvel of the natural world.

And one of the most successful and species on the planet.

It's now been ten days since our ants were released from the nest.

And I've come back to see how far the colony has come.

And straightaway, I can see foraging trails now traverse environment from end to end.

The fungal gardens I saw last time have grown,

and I can see some new ones too.

Since they arrived in their new home, the ants have made real

progress towards getting their society up and running again.

One of the best examples of this is at the very bottom of the nest.

We're now in the bowels of the colony,

right down below where all the ants have their nest chambers.

And the reason we're down here is that there's a lot happening.

The ants have a waste dump down here.

All that leaf processing produces a lot of waste that needs to be dealt with.

And ants cope with the trash burden in a similar way to us.

This is an ant landfill.

Now, what we've got here is a waste dump they've made

actually in the trough that surrounds the whole colony.

And that's a water-filled trough, which is designed to keep the ant in.

What's happened is, the ants have built a waste dump.

And because it's wet and the bacteria are building up in here,

the smell of decaying ants and fungus is overpowering, it's disgusting.

Normally, the dump is placed in chambers at the bottom of the colony

where workers turn over the waste as a gardener does their flowerbeds.

This speeds up the breakdown of potentially harmful substances.

But the ants aren't just dumping their garbage down here,

they are also disposing of dead bodies.

Over on this side is the graveyard.

Now, this is actually very interesting.

The ants, of course, don't live for ever and when they die,

their remains are taken down and dumped out of the colony.

And that in my hand is just dead remains of literally hundreds and hundreds of ants,

of all castes, small workers, large workers, soldiers.

So, when the ants have no longer any function

and when they die they are simply taken out and dumped.

The main reason why ants have to keep the waste and the dead remains

of ants out of the way of the colony is that when you're

in such high abundances in the colony you don't want any diseases

to spread so you have to maintain your environment, it has to be clean.

So anything that could possibly rot is removed.

Seeing the dump and the graveyard really brings it home to me

just how sophisticated the ant colony is.

It's easy to see why people have looked at the ants

and thought they were seeing our own world reflected back.

We've even used the language of our own social structures to describe ant society.

Workers, soldiers, the Queen.

But, is ant society really organised in this kind of hierarchy?

To answer that question, we need to take a closer look

at the roles of the different ants in our colony, especially the Queen.

Tended round-the-clock by workers and fiercely protected

by soldiers, she's the colony's most prized member.

But does that mean she's in charge?

I can't introduce you to our colony's Queen because she's deep in

a chamber somewhere behind me, and I wouldn't want to disturb her anyway.

But Adam has brought a Queen from a much smaller colony

and we can take a closer look at her.

So, what we've got here, George, is one I dug out the ground in Trinidad.

There's the Queen. I've never seen the Queen before like that.

She's an impressive creature, she's impressive in her own right,

but when you see her next to the smaller ants it gives you an idea of how big she is.

We can see the Queen's enormous body protruding from the fungus,

with smaller ants attending her.

Inside her large abdomen are the ovaries that allow her to lay up to 30,000 eggs a day!

So, is the Queen in our colony roughly the same size?

Yeah, the Queen in our colony will be exactly like this.

This is the same species from the same place.

She's a beautiful sort of velvety-brown colour? Yeah.

I just want to just touch her. Yeah.

She's beautiful.

Our colony will only ever have one Queen in residence.

But once a year, it will produce new queens who will leave the nest to start new colonies.

This is also the only time the colony will produce males,

and these males have one sole purpose - to mate.

Leafcutters have never been observed mating in the wild,

but we can see how much of a large-scale operation this is

with the British species, the wood ant.

In late summer, the colony produces hundreds of new queens and males.

These ants have wings and they fly from the nest en masse to find a mate.

This event is called the nuptial flight.

These winged individuals are the females, the new queens, the males that they'll mate with.

It is a very effective way of dispersing, not just mating

with individuals from another colony, but also spreading out and spreading the colony far and wide.

After the nuptial flight, the males simply die.

The Queen will never mate again.

She's now ready to start a new colony.

From now on, her role is to lay eggs.

It's a staggering thought that all the ants in our colony have the same mother.

And as males are only produced for the brief mating period,

all the ants we see here are female and they're all sisters.

And there's something else that's intriguing here.

All the eggs the Queen lays are essentially the same.

So how can they become all the different kinds of ant that make up the colony?

The workers are in control of what goes on.

Because when the Queen lays eggs, she doesn't lay an egg

for a minor worker, or a soldier, and an egg for a queen, she just lays an egg.

So it's totally how that larva that hatches from the egg is

nurtured, how much food it's given that determines what it turns into.

So the workers who feed the larva they are actually controlling

the number of soldiers and worker castes produced within the colony.

They're really flexible and dynamic and can respond to what's going on in the environment.

So if we start disturbing this colony, they'll start producing more soldiers.

And it's happening right in here now?

It's happening right here, all over these fungus gardens, they're rearing these workers up

within these fungus gardens and they're responding to what's going on, responding to the lights,

to heat, to food, responding to what the Queen's doing in terms of how many eggs she's laying.

And that information is somehow integrated in the workers, it's all about the workers this colony,

it's not really about the Queen, she's just popping out eggs.

So the ant colony has a very particular form of social organisation.

The Queen is the only ant who reproduces.

Her eggs will become the workforce of the colony.

Each generation raises the next, from egg to adult.

This results in multiple generations working together for the good of the colony.

And these attributes put our ants in a very special group of insects.

The truly social or eusocial insects.

Eusocial insects are phenomenally successful.

Where as they only make up less than 5% of all insect species,

they account for the majority of the insect biomass on Earth.

Apart from ants, the major groups of eusocial insects are termites, wasps and bees.

WINGS VIBRATE

Together, these insects outnumber all the others on Earth combined.

Being eusocial is one of the most important,

evolutionary developments in the animal kingdom.

It's such a significant step,

that scientists are trying to discover when it first occurred.

And what it is about being eusocial that gives these insects such an advantage.

Dr David Grimaldi is the curator of fossil insects at the American Museum of Natural History.

He's spent 25 years researching specimens of ants and other insects millions of years old.

This sample is from the Cretaceous era.

These early ants were wandering around at the time of the dinosaurs.

Dinosaurs died out but the ants went on

to become astonishingly abundant.

These ants are a window into prehistory.

The sap of ancient trees trapped them as they foraged and then

hardened into amber, preserving them for millions of years.

Now these remarkable specimens are helping scientists discover

more about the origins of eusocial insects.

There is one remarkable piece from the Cretaceous,

probably the most important piece, a chunk of 100-million-year old amber,

that contains ten individuals, almost certainly workers.

The ants are so rare in Cretaceous amber,

so the probability that you would get ten individuals preserved

in one piece just based on chance alone is astronomically improbable.

Unless of course, they were social.

Other ancient samples revealed that being social didn't just

affect the ants' behaviour, it also changed their anatomy.

These ants have pouches to share food with their sisters.

This feature of and anatomy is most clearly seen today in the Australian honeypot ant.

These ants are so full of food, they can hardly move.

They're like living larders, feeding their sisters.

When you have many, many individuals that specialise in foraging

and protection and nursing of the larva and in defence of the nest,

you can be much, much more effective.

So, being social is a tremendous adaptation,

perhaps one of the most effective adaptation is in the animal kingdom,

because we can see that when ants become highly, highly social,

they become a very dominant life form.

The advantages brought by eusociality have allowed these

insects to dominate the globe.

Ants have been called ecosystem engineers,

as they can change the environment around them.

Nutrients released from their underground nests fertilise

the surrounding soil,

which in turn promotes the growth of plant life on the surface.

With more plants come more animals, and studies have shown that an

ant colony can actually increase the diversity of animal life around it.

Eusocial insects can even affect our lives.

Without bees to pollinate our plants,

we wouldn't be able to grow enough food crops.

You might say it's eusociality that feeds our world.

It's been 15 days

since we began following the progress of our ant colony.

In that time, they've been far from idle.

They're now well-established in a nest we built for them.

The most amazing change since the colony has really become

established is the incredible growth of the fungus gardens.

You can see the green leaf material where the fungus hasn't quite

grown yet, so it's just becoming white from the base up.

You can see at the very outside edge,

you've got all the chewed, green material,

the food for the fungus, and then the fungus moves up.

It's fragile as anything.

It's just...

It's just a miracle of micro-engineering, this.

And it's one of the most beautiful things I've ever seen.

To see how much progress the ants have made re-growing

their fungal gardens, we're going to open up a nest box again.

Look at that. There we go. They're not happy about this.

You can really see the structure of the fungus garden.

They are really... That whole thing is hollow

and there is a soldier in there.

This is their very reason for being, isn't it?

That is the major resource.

Yes, it's not like a mushroom or a toadstool. It's very fragile.

It's more like a sponge.

There's a huge surface area in here, so there's lots of little

chambers and cavities and places for them to feed. That is unbelievable.

It's a really beautiful structure. Really soft. Yeah.

It's these white tufts, produced by the fungus, that feed the colony.

They contain just the right balance of nutrients to support

the developing brood.

This fungus garden alone, grown since the ants arrived,

will feed thousands of new ants.

It's the clearest indication yet

that our leafcutter colony is thriving.

Before we get completely inundated,

I think we're going to have to put this back down very gently.

Put that back.

Ah, one's gone down my front. Ah-ah! Ouch!

HE GASPS

Ah, yep.

See, they're incredibly good at defending. This is their colony.

And we've broken into it. And that's the result.

I don't think we'll be doing that again.

I'm beginning to regret this now.

We've had a good look at the fungus garden,

and we've seen a great response, but yeah, perhaps not again.

Away from the nest, there are more signs of progress.

The ants are constantly monitoring their long foraging trails.

If any blockages occur, workers swiftly clear them.

What our colony is showing is organisation on a massive scale.

And that begs an important question.

How did they organise all this? How did they know what to do?

Humans wouldn't be able to do this without some kind of hierarchy,

without somebody taking responsibility, giving instructions.

And, as we've seen, this is not the case with ants.

There is no hierarchy.

No central command or control from any individual or group of ants.

Not even the queen.

So how do the ants do it?

To help answer that question, Adam's going to put them to the test.

I've set the ants a problem. I've given them a Y-shaped trail.

At one end of that Y is food and at the other end is nothing.

And I've connected that trail up to the main trail,

so they're pouring down out of the nest, coming onto this trial

and are being faced with a choice.

Do they go left or right?

Our ants have a clear 50-50 choice between right and left.

But after just 20 minutes,

virtually all of them are heading down a path that leads to the food.

So, how do they know where to go?

At this distance, they can't see the food.

Their eyesight isn't good enough.

Instead, it's all down to be ingenious way the ants share

information with each other,

using their acute sense of smell.

The ants moving down here are laying behind them

a chemical pheromone trail that marks the way for other ants.

They can detect tiny amounts of these pheromones

using their antennae.

When an ant goes out foraging, she leaves the pheromone trail

on the ground behind her that her sisters are able to follow.

If she finds food, she will then lay down even more pheromone on her

way back to the nest,

making the original trail even stronger.

If she doesn't find food, she won't lay any more pheromone

and the trail simply evaporates away.

The stronger the pheromone trail,

the more likely an ant is to follow it.

And, in turn, add her own pheromone to the route.

When this is applied to hundreds and thousands of ants,

very strong trails are produced that link the nest directly to food

sources in the environment.

And what that means is that the branch that's got

food at the end of it is much more concentrated in terms

of pheromone than the branch that doesn't.

So that when ants come to that fork and they have to make a decision,

they follow the trail head that has the most amount of pheromone.

So they're much more likely to go right than they are to go left.

That means these ants can organise themselves.

The queen's not in the colony going, "Turn right, turn left,

"take the third exit."

They follow the trail of pheromone to the food.

So each individual ant is dealing with simple signals, simple rules.

But collectively this system achieves complex results.

It enables the colony to find new food sources, exploit them

efficiently and react swiftly when they are depleted.

This is what underpins the entire leafcutting operation.

But pheromones aren't the only way leafcutters communicate.

They're constantly exchanging information,

and with the right technology, we can even listen in.

Is it possible to actually hear?

Yes, luckily, I'm festooned with gadgets,

so we can actually...

We can actually mic these up.

Dr Gadget.

Yes, we can get some sound out of these.

They're very small animals and it must be a very faint noise.

Yes, it's a very small noise and it's quite high-frequency,

but if we just press that on to there...

To human ears, the ants' world seems silent,

but amplified by the microphones, the leaf comes alive with noise.

'And there is one particular sound we're listening for.

'In amongst the sound of leaves being cut

'and ant footsteps is a high-pitched chirrup.'

ANTS CHIRRUP

'This is stridulation,

'a sound the ants make by rubbing two sections of their abdomen together.'

That little chirrup? Yeah. There. Yup.

So they're making this sound but it's part of a group of sounds

they make, these sounds.

'That little chirruping noise is a recruitment signal.

'The more nutritious a leaf is, the more the ant make this noise,

'sending a cascade of vibrations through the plant.

'And this draws other ants to the tastiest part of the plant,

'which means the ants will tend to take the best leaves first.'

But there's more to stridulation than simply leaf cutting.

It can make the difference between life and death.

As they build their underground network of tunnels and chambers,

our ants, just like human miners, face an ever-present risk.

A roof collapse could bury them alive.

To discover how they respond, we're going to simulate this catastrophe.

And time for another gadget.

This is a plate microphone,

so this is recording directly from what's on the surface.

'We're going to put an ant on the surface of this microphone

'and bury it with soil, just like a roof collapse in the nest.

'And then, we listen.'

You put that on, and I'll... I'll wrangle the ant,

you get some earth on there. Ready?

There we go. Buried alive.

So this is going to be the sound of ant fear.

This is an ant that has been trapped under the soil.

It's calling its nest mates.

ANT CHIRRUPS

There's a bit of hiss there, but you can hear...

That's the noise they're making

by moving their abdomen backwards and forwards.

That's very obvious, isn't it?

It's a very clear signal that causes a very specific behaviour.

"Come over here, dig me out."

'What we're hearing is the ant's alarm call.

'She is appealing to her nest mates for help.

'With only a loose covering of soil, this ant

'isn't in any real danger.

'As she digs her way to the surface, the noise of panic stops

'and she emerges.'

There we go. She's free.

You actually get a window into their world. It really is amazing.

Because they're so small, we can't hear these sounds without

fancy microphones and things, but once you start hearing them,

you realise they are living in a very complicated world.

They produce sounds, they've got chemicals.

It's a very complex world they're in.

So this is how the ants organise themselves.

Each individual follows simple rules using communication tools

like pheromones and stridulation.

And applied to huge numbers of individuals,

these simple rules allow the colony to solve complex problems.

This is collective swarm intelligence.

Ant species around the world use this ability to tackle

problems that challenge even us humans.

'I've come to Bristol to discover how one species of ant uses swarm

'intelligence to make a vital decision.'

These are Temnothorax albipennis, also known as the rock ant.

They're absolutely tiny, only about two millimetres long.

Don't let their size fool you, these tiny creatures are smart operators.

They use an ingenious set of rules to make decisions that

test us to the limits.

'For instance, house-hunting.

'We might find it stressful.

'But to the rock ants, it's a matter of life and death.

'Here, at the University of Bristol's ant lab,

'Professor Nigel Franks

'has spent the last decade studying the behaviour of these insects.'

So this is a rock ant nest that you have set up in the lab,

pretty similar to what you would get in the wild? In a sense, yes.

In terms of the spatial scale, the spatial arrangement,

the colonies normally live in very, very flat crevasses in rocks,

with maybe a millimetre between the floor and ceiling,

so we can keep them in these nice simple microscopes like this.

As soon as they get them destroyed, particularly if they lose

the roof of their nest, in the wild, they can't do anything about that.

They simply have to find a new nest site to live in. OK, let's do it.

'Removing the roof effectively destroys the nest.

'In the wild, this would be a perilous situation for the colony.

'It's time to find a new home as quickly as possible.

'We've given them a range of options of varying suitability.'

Right over here we've got a really poor nest.

Too small and, in addition to that, it's got some dead bodies in there.

It's an absolute slum. Over on this side we've got the absolute des res.

We've got a nice big nest, hygienic, clean

and it's made dark with a red filter.

So we've got from really superb palatial accommodation

right down to an absolute slum.

'The ants go scouting for a new home.

'Like a team of insect surveyors, they inspect each site,

'checking factors like hygiene and light intensity.

'It doesn't take them long to discover our des res.

'It's clean, it's dark, but is it big enough?

'This is where their ingenious system of rules is revealed.'

They will go inside, they will actually pace the map in a way and

work out the floor area to see if it is big enough for a whole colony.

'When the ant encounters a potential new nest,

'she criss-crosses it many times.

'As she does so,

'she leaves behind her on the ground a tangle of pheromone trail.

'She will then leave the new nest,

'but that's not the end of her assessment.

'A short while later, she returns for a second inspection.'

They then sort of smell the ground

and every time they cross a previous path, they note it.

And, essentially, if they were in a very large nest, the frequency

with which they would cross a previous path would be very low.

If they're in a very small nest, it would be very high.

'So by counting the number of times she crosses her own path,

'an ant is able to very accurately work out how big a new nest is.'

So it's a beautiful example of the ants using an exquisitely simple

rule to solve a very complicated problem.

'But one ant's view isn't enough.

'Like us, they need a second opinion. And quickly.

'Because without a nest, the colony is in danger.'

If she thinks a nest is suitable, she will return to the colony

and she will attempt to recruit one other nest mate by a process

we call tandem running.

'To get that second opinion, the scouting ant

'physically leads a nest mate to the new location on a tandem run.'

'When the tandem runners arrive at the new nest,

'the leader heads back to the colony to recruit another ant,

'whilst the follower carries out her own survey.

'If she thinks the new nest is a suitable new home,

'she will also return to the colony and recruit yet another ant.'

And so the numbers snowball slowly. One, two, four, eight, etc.

'Because time is of the essence,

'they can't wait for every ant to agree.

'So, once a critical number of ants, which can be as few as ten,

'are in favour of the new site, another rule kicks in.

'Tandem running stops, and a moving behaviour begins.'

They will run back to the old nest

and start picking up their nest mates, whacking them

over their shoulders, so to speak, and running them to the new nest.

And they can run with an ant over their shoulder or a huge brood item

in their mandibles at three times the speed

that they can lead a tandem run. So it's like a gear change.

It's like going from second gear to fifth gear, and - wallop!

The colony commits and will rapidly emigrate to the nest

they have chosen.

The rock ants have used simple rules, applied one after the other,

to find a swift, collective solution to a life-and-death situation.

And this is just one species of ant with its own set of rules to

solve its own unique set of problems.

In the wild,

driver ants create imposing trails guarded by huge soldiers to

ensure the safe passage of the brood from one place to another.

The Asian weaver ants build intricate nests

using their own brood as glue guns.

This is an insect using a tool.

All of these behaviours, wonders of the natural world,

owe their existence to simple rules followed by colony

members in the same way over and over again.

Back in our colony, we are approaching

the end of our project to explore the world of the ants.

But there's one cast of ant whose roles

and behaviours remain more mysterious than any other.

The soldiers.

As we've seen, they tend to remain hidden deep within the nest.

But we're about to discover some of their secrets.

In our most ambitious experiment,

we've used radio tracking technology to follow the movements

of a group of soldiers day and night over a period of ten days.

Now, the results are in. And Adam has been crunching the numbers.

How difficult would this have been in the wild colony?

This sort of thing would be impossible, because in the wild,

we'd be underground right now.

You know, you can't use this sort of technology

deep in the ground in any sort of effective way.

So we've got no insight about how these things happen

in a natural nest. That's why this is such a nice opportunity.

So now you've begun to analyse all the results from the tagging.

What's beginning to emerge?

Well, what's really interesting is that individual soldiers

are behaving in quite a strange way. They're patrolling.

So one, for example, goes from this box to this box to this box

back again, back again, over about 20 hours.

We have others doing exactly the same thing,

oscillatory behaviour between boxes.

So almost as if each of the soldiers has a sector

of the nest they control.

Our results reveal the soldiers as a highly organised security force.

Every ant we tag has an oscillating patrolling behaviour,

all of it focused around the fungus gardens.

And we discovered there's more than one type of patrol.

Some soldiers moved back and forth between just two nest boxes.

Others have a much larger route,

visiting five or more boxes over a period of days.

This area here is a hotspot of activity,

with a number of different patrols converging on one box.

Due to the extra security presence,

it's our suspicion that this area is the location of the queen.

Overall, what we see is an organised security network, operating

on a regular schedule, guarding the prized assets of the leafcutters -

the queen...

..the brood...

and the fungus.

That makes sense, because they are the high-value

resource of the colony, and that's where the young are.

Yes, so the soldiers seem to be kind of barracked into these

areas where they've got something to defend.

Our data indicate that the soldiers are hardwired to patrol the nest,

poised and ready to repel anything that threatens the colony.

To see that response,

we can simulate an attack on the nest by pushing a camera down into it.

To the ants, this appears to be a predator,

and it triggers a call to arms.

Ants near the camera release a pheromone that signals alarm.

This pheromone attracts more ants onto the scene.

Almost instantly, there is a whole swarm attacking the camera.

Once again, they are following a simple rule.

Defend the nest.

But in the wild,

following this rule is likely to cost some ants their life.

This is a praying mantis feeding on driver ants.

When the colony responds to the threat, one of the first

ants on the scene throws herself into the jaws of the mantis.

She stops the insect taking any more of her nest mates,

but sacrifices her life in the process.

And as more individuals arrive, the tables turn,

and the predator literally loses its head.

To achieve the collective goal of defending the nest,

individual ant lives are expendable.

And this is the darker side of the parallel that people have

drawn between humans and ants.

Instead of a model of industriousness, a world of mindless

automatons, following rules, unable to control their destiny.

There's a moment, I think in the 20th century,

where certainly all those ideas of industriousness are gone,

the ant becomes a very scary thing.

Ant society becomes everything that humans want to avoid.

I think there are a couple of things that add to that.

The experience of the First World War,

and the sense of soldiers being sent off anonymously to their death.

Also, I think, the experience of mass life in factories.

You know, think about Henry Ford,

think about those cars rolling off the production line.

That's really very much like our leafcutter ants,

and their production line with the leaves.

There's no room for individuality, it's pretty horrific.

The ant is everything we don't want to become.

It also find it's way into science fiction films.

I mean, I remember a film called Them, where the

Earth is being threatened by these giant ants.

'There is no word to describe them.'

SHE SCREAMS

It's a classic Communist-era movie, in fact.

The sort of, the unknowability of these ants,

the sense that their operating under some system that's

swayed by propaganda, that we can't even really comprehend.

They are the classic Commie enemies.

Is there any type of gas we could use?

No, we can't take a chance, it might poison the whole city.

So bringing things right up-to-date now, there has been

a change of emphasis, the interest in what ants do is now altered a bit.

That's right, we've become increasingly interested in them

as technological systems, if you like. As natural computers.

And we're interested in the way that they solve problems,

and the way in which they, in particular,

find the most efficient way of solving problems, the most efficient

ways of foraging for food, bringing it back to the nest, and so on.

It's a radical thought.

It suggests we could see our ant colony as a giant,

powerful computer, that can solve complex problems.

Problems like finding sources of leaves, and delivering them

efficiently to the parts of the nest where they are required.

As we've seen, the colonies solve these problems using a logical

system, based on pheromone trails.

And this system is now inspiring new technologies,

designed to solve some very large human problems.

Here, in the Texan heat, a very cold industry is at work.

This is Air Liquide, a company that supplies tanker loads of compressed

gas to thousands of customers, from hospitals to oil refineries.

I'm here to meet Charles Harper, to find out how insight from ants

is helping the business solve a fiendishly-complicated problem.

Here we monitor the supply of, and the production of all our gases

and our liquids in the United States.

We have about 10,000 customer sites to deliver to,

we have 1,000 trucks and drivers to dispatch, so on any given day we

have to know who needs a delivery, and where to source the liquid from.

Finding the best routes to get the right truckloads to the right

customers every day is a massive logistical challenge.

And this challenge has a name - the travelling salesman problem.

The task is to find the shortest route between a number of cities,

visiting each only once before returning to the starting point.

With five cities, there are only 12 possible delivery routes.

But as more destinations are added,

the number of potential routes skyrockets.

A trip with just 15 cities has over 40 billion possible routes.

Air Liquide faces a travelling salesman problem that has

trillions of possible solutions.

So for help, they turned to the ants.

Inside this computer, there is a programme based on ant

behaviour, it's called an ACO, or ant colony optimisation.

So, you're running your delivery network very similar to

an ant colony going out foraging,

only instead of bringing food in, your looking to take goods out?

Exactly. Just the reverse, and in our particular case,

we're delivering food out to the customers,

in this case it's liquid oxygen or nitrogen,

but as an ant colony would bring food

and supplies back to the mound, we use that ant motion, and ant

reinforcement in the pheromone trail to simulate our routes.

The programme sends out digital versions of ants

to investigate potential routes.

Just like our own leafcutters,

the digital ants lay virtual pheromones as they go.

Shorter routes become reinforced with pheromone, as more

and more ants begin to follow them.

While the longer roots begin to evaporate, and are ignored.

It's the same technique our ants

use to establish the quickest route to a food source.

The digital ants quickly and efficiently identify the better

options, so there's no need to calculate every possible route.

And Air Liquide gets a highly-efficient way

to run its complex operations.

But solving complex delivery problems is just

the beginning of what ant colony optimisations can do.

Their ability to identify the best

route from billions of options is now helping scientists reach

far more ambitious destinations.

Dr Max Vesile, from the University of Strathclyde's

Advanced Space Concepts Laboratory, has studied how lessons

from the ant colony can be applied to travelling through space itself.

Well, one thing we decided to do some time ago was to try to use

ants to try and plan a trajectory from one planet to another,

passing by a number of intermediate planets, and exploiting

their gravity to change the velocity of the satellite.

If you send a spacecraft through the gravitational

field of a planet at precisely the right angle,

it acts like a catapult,

propelling the spacecraft across the solar system.

This is called a slingshot.

By using more than one planet, it's possible to

slingshot across the solar system, without the need for tons of fuel.

But calculating the best combination of slingshots

is extremely complicated.

So, you need to go from one point to another,

but you've got lots of points in between,

that you need to pass to get that boost?

Exactly, so what we asked the ants do, is to tell us

the best possible sequence of planets to reach the destination.

It's again similar to the travelling salesman problem,

but in this case, these cities are moving, and we have the

additional rule that we can visit multiple times the same city.

And on top of that, basically the cost of going from one city to

another, depends on the time in which we reach the city.

So, this is a much more complex problem

than ants are solving on Earth? Definitely, yes.

This research work is still in its infancy, but Max has tested

his galactic version of ant colony optimisation on the Cassini probe.

Launched in 1997, it flew to Saturn, propelled there by slingshots,

past Venus, the Earth, and Jupiter.

The digital ants not only replicated this route, but also

suggested two others that would have been quicker and more efficient.

It's literally millions of miles away from leafcutting.

We've reached the end of our project to explore the hidden world of ants.

The past month has revealed the sheer scale

of their organisational powers.

Well, it's incredible to see how far the ants have come.

We've uprooted them, and brought them halfway around the world.

We've seen them rebuild their entire society

in the space of just a few short weeks.

They've now taken control of this new territory, from the outermost

plants to the depths of the nest, and the colony is thriving.

We hope it will continue to be the subject of scientific observation.

But for me, the colony has already helped to show ants in a new light.

Rather than a vast number of individuals, the colony is

really a super-organism, functioning in a complex and sophisticated way.

The different ants like cells and organs and animal,

have different functions, but operate together as an ordered whole.

Seen as a super-organism, the ant colony truly is one of the most

impressive achievements in the evolution of life on our planet.

And the more we come to understand it,

the more we can harness the genius of the ants for our own benefit.

We now have a better understanding of the parallels

between ants and ourselves.

But we're only just beginning to understand what they can teach us.

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