Our planet is the greatest living puzzle in the universe.
A collection of worlds
within worlds.
Each one a network of relationships
and connections
between all their living parts
leading to the diverse and complex world we live in.
And at the heart of many of these worlds
is a very special group of animals.
The insects and their close relatives,
the arachnids and crustaceans,
classed together as the arthropods.
Together, they account for 80% of all animal species on our planet.
In these three specials,
we're going to explore the connections and relationships
that they have with us, our planet
and with each other.
Ultimately to understand how this group
hold the key to life itself
inside nature's microworlds.
Humans evolved around 200,000 years ago
into a world that was dominated by the arthropods.
In that time, we've learnt to live alongside each other,
taking the benefits and putting up with some of the annoyances.
But do we understand what life would be like
without this group of animals?
How many of us really know
how intricately linked our lives have become
that, without the arthropods, life as we know it would not exist?
Some even question
if survival of the human race would be possible at all.
But how can this be?
What have the arthropods ever done for us?
The ways they affect human life are diverse and far reaching
and to really understand the importance of this influence,
we need to unpick the relationships,
both good and bad,
that we have with the arthropods.
One of the most intriguing ways they influence us
occurs in the forests of Kenya.
These driver ants are searching for food.
They're efficient hunters
moving through the forest like a tidal wave.
They'll eat any living animal in their path.
Colonies can number up to 22 million
and it's said that even elephants will turn and flee
when they see them coming.
These lethal predators are actually totally blind.
They rely on touch, smell and chemical signals to find their way.
The soldiers flank the raiding columns of workers
with immense jaws raised.
Anything that can't outrun them
risks becoming their prey.
This is perhaps how most of us view arthropods -
creepy crawlies that are nothing more than a problem.
But their presence is actually
a real asset for these villagers.
The ants can capture up to 100,000 insects in a single raid,
providing invaluable pest control for the farmers.
Pests inside homes and in surrounding fields are removed,
dismembered and devoured.
In fact, the whole place is given a five-star ant clean-up.
Thanks to their highly effective cleaning raids,
these ants play a key role
in the lives of the locals.
But arthropods can provide us
with something even more important than a service.
They can provide us with one of the essential elements of life.
900 miles south of Kenya
lies Lake Malawi.
Beneath the water, something's stirring.
Trillions and trillions of lake fly larvae are getting ready to emerge.
After many months buried in the sediment on the lake floor,
they'll take to the air to mate.
Towers of mating flies stretch hundreds of metres into the air.
Like smoke, they rise
from the surface of the lake.
The towers of flies are swept by the wind towards the shore
and towards human habitation.
Here, they cloak vegetation
and engulf whole forests and villages in their path.
This may seem like an annoyance,
but, actually, these flies present great opportunity.
Villagers sweep baskets through the air to catch the flies.
The biomass of these flies is equivalent to huge herds of game
that roam the surrounding plains,
but they're far easier to catch.
The flies are then made into patties
and fried in hot oil.
Each patty contains half a million flies
and has seven times more protein than the average beef burger.
For people who have little protein in their diet,
this can be a lifesaver.
It may feel a long way from our idea of a perfect meal,
but the importance of eating arthropods
shouldn't be underestimated.
Over 11 million tonnes of crustaceans
are consumed by humans every year.
In Botswana, the mopane worm collection industry
is worth millions of pounds each year.
For 2.5 billion people worldwide,
insects are a vital source of food.
More than a thousand insect species
form a regular part of the human diet.
Rich in vitamins, protein and minerals.
It's mainly in the West
that people are uncomfortable with the idea of eating insects.
But the United Nations believe
that eating insects instead of mammal meat
may provide a solution to stamping out famine
and reducing climate change.
The raising of livestock such as cows, pigs and sheep
occupies two thirds of the world's farmland
and generates 20% of all greenhouse gases.
With the human population projected to reach nine billion
in just 40 years' time,
the consumption of arthropods
could provide a healthy Earth-saving measure.
So, in the future, arthropods have the potential
to address our global food crisis.
That's no small claim.
But they've also played an enormous role in shaping our past
to such an extent that human life, as we know it,
would not exist if it weren't for this next arthropod product.
It all started with a cocoon
and a beautiful piece of cloth.
China - home to a billion people
and a very special arthropod.
This is a silk worm caterpillar.
They eat only mulberry leaves.
And, after 50 days of feeding,
they'll be 10,000 times heavier and ready to transform.
25% of their body mass is made up of silk glands.
They spin a cocoon using a single thread
which can be over 900 metres in length.
And it's this silk that forms the basis of an industry
that's shaped our history
and today, has a commercial value
of up to £300 million.
The cocoons are boiled and precious silken threads begin to unwind.
But this arthropod product is not only responsible for human clothing.
It's shaped our culture for over a thousand years.
The transport of silk from Asia towards Europe
led to the establishment of the famed Silk Road around 200 BC.
This 4,000-mile trade route
forged relationships between different and diverse cultures.
And was pivotal in the development of the civilisations
in China, India, Europe and Arabia.
So silk has shaped human culture and distribution,
but there's another arthropod product that's valued so highly
humans will risk their life trying to collect it.
The Himalayas, in Nepal.
These men are climbing 400 metres up sheer cliffs
to steal from giant honey bees.
They're the largest honey bee in the world
and their stings are notoriously painful.
So what could make men risk their lives in this way?
Honey!
These bees, like honey bees the world over,
take nectar from the surrounding flowers
and spit it into the cells in the comb.
Enzymes in their saliva break down the sugars
and water evaporates until the condensed honey remains.
This honey will be the colonies' sole source of food
during the colder winter months
and they'll give up their lives to protect it.
So the honey gatherers will not only have to deal with perilous heights,
but also with angry bees.
When the men finally reach the comb,
they must manoeuvre sticks
to work free a section of honey.
With little protection against the stings,
they must work quickly before being overcome by the bees venom.
The honeycomb is dropped into a suspended basket
and then lowered to the ground.
They leave a large section of the comb intact
so the colony can rebuild its honey supplies.
Job complete, the men can descend to enjoy their hard-won prize.
Honey's made up of 80% natural sugars
and so, provides a vital energy-rich food source
for these mountain dwellers.
So prized is this product
that the farming of arthropods for their honey has now gone global.
Around 1.2 million tonnes of honey is produced worldwide each year.
When you think that one little bee in its entire lifetime
produces only about a spoonful of honey,
that's a humbling amount of work
from our arthropod friends.
But honey isn't the only product that bees provide us with.
Bees and their relatives
have a much more far reaching and significant effect on us humans.
Without which, it's questionable if humans would survive at all.
And to see what this is,
we must examine a wonderful process happening all around us
and responsible for shaping the world we live in.
The coastal cliffs of Sardinia,
in the Mediterranean,
are home to an unusual plant.
The dead horse arum.
It looks like a dead rotting animal
and has a smell to match.
This canny flower even raises its temperature
by as much as 20 degrees above the surrounding vegetation
to complete its disguise.
The smell is taken by the wind
and it's not long before the arum is noticed.
These flies are hoping they've found a carcass
on which to lay their eggs,
but, instead, they become trapped.
Inside the flower,
they brush against the female stigma
releasing any pollen they're already carrying.
This flower is now pollinated.
Spines prevent the flies' escape and they're trapped.
Overnight, when the flies are inactive,
the spines wither and the male pollen above them ripens
ensuring that, in the morning,
each exiting fly is coated with pollen to take to the next flower.
This flower has invested everything
in the process of cross-pollination.
It's modified its appearance,
its smell, its temperature
and its internal barriers,
all to ensure the transfer of pollen grains
from one plant to another.
And it's this process of pollination
that's the next key
to why the arthropods are pivotal to human success
and to our very own food chain.
As much as 35% of all human food
is dependent on pollination by arthropods.
Across the world, the value of crops pollinated by insects
is over £120 billion a year.
Without them, we wouldn't have apples, almonds, cherries, oranges,
tomatoes or squash on our supermarket shelves.
84% of crop species grown in Europe
still depend on insect pollination.
Without insects, our crops would flounder,
supermarket stocks would plummet
and life on Earth would irreversibly suffer.
But to really understand our relationship with the arthropods,
we need to examine their negative effects as well as the positive.
The deserts of West Africa.
Moisture in the soil and increased temperatures
provide the triggers for a mass hatching.
Eggs that may have lain dormant for 20 years hatch
and flightless locusts, called hoppers emerge.
These hoppers follow the smell of freshly sprouting grass.
After about 20 days of feasting,
they transform into winged adults and form a swarm.
A swarm can cover an area of 1,000 square miles
and can literally blot out the sun.
They eat their own body weight in food each day.
En masse, they can get through 200,000 tonnes of crops,
enough to feed half a billion people.
Many arthropods have the potential to reach biblical proportions.
Their ability to reproduce quickly and prolifically
means their numbers, left unregulated,
can snowball out of control.
For us humans, that can present a real problem.
And there's a parasite that's utilised this breeding success
and today, it's the biggest cause of human fatality on our planet.
It kills 3,000 people every day
and without arthropods, it wouldn't exist.
Throughout history,
this relentless killer has claimed more victims than any other disease.
It's killed more people than both the world wars put together
and at least 40% of the world's population are at risk.
The disease is carried by the Anopheles mosquito
and it's called malaria.
But, really, this mosquito
is just a pawn in a parasite's game.
The parasite lives by eating the red blood cells
of the victim it attacks.
When a mosquito bites an infected person,
it sucks up the blood containing the parasite into its gut.
The parasite multiplies...
..then, burrows into the mosquito's saliva gland...
..where it's squirted into the blood
of the mosquito's next victim.
And so, the cycle continues.
But can we really blame the mosquito?
It gains nothing from carrying the parasite.
And, ironically, mosquitoes,
along with other arthropods,
might be the ultimate solution to this deadly disease
in their ability to regulate each other.
An example of this is played out
in a field in the South Downs.
These aphids are doing what aphids do best -
multiplying.
They're breeding machines
and, by the end of a season,
a single aphid can have produced over a billion descendants.
Each aphid uses their specialised mouth parts
to suck out the plants' juices.
Left uncontrolled, they can devastate a whole field of crops.
Luckily for farmers and gardeners,
there's a crack team of predators on standby.
Firstly, the colourful but ferocious ladybird.
One ladybird can eat over 5,000 aphids in a lifetime.
But working alone, they'd have their work cut out
to keep up with the prolific breeding of the aphids.
Luckily, they've got backup.
Money spiders parachute in from surrounding fences and hedgerows.
The spiders spin delicate but lethal orb webs
and wait for their prey to arrive.
When the bumbling ladybird has had her fill,
her movements dislodge further aphids
that drop into the silken traps below.
This natural balance of predators and prey
may seem only relevant to gardeners and farmers,
but the global importance of this natural biological control
is not to be underestimated.
Pest control services provided by insects were valued
at over 60 billion dollars a year, in the USA alone.
This is a service we really can't afford to lose.
And the arthropod regulators could potentially provide some hope
against the worst disease the human race has ever faced.
There are plans for a non-malaria-carrying mosquito
to be released to outcompete the deadly malaria-carrying ones.
So we've seen how arthropods provide us with food and products.
How they've shaped our distribution and culture.
We've seen how pivotal they are to our own food chain
and how their presence can regulate pests and even fatal diseases.
But there's one final key to how they influence our lives...
..one final offering from the arthropods
that could shape the way we exist and operate in years to come.
In this vast colony,
every army ant appears to be following a master plan,
like tiny cogs in a huge machine.
They allocate resources depending on environmental conditions.
If a rich food source is found,
workers will appear to deal with the bounty.
They build organised highways with no congestion.
They construct shelter and a place to rear their young
using their own bodies.
They stage foraging raids
and vacate an area of forest when food sources dwindle.
They're efficient, responsive and smart.
Everything our human organisations strive to be.
But this colony doesn't function
like any organisation we humans are familiar with.
There's no central control, no figure of authority.
The queen ant may have her lofty title,
but plays no role in coordination.
And we're just starting to learn how such efficiency is achieved.
Haulage companies and airports are learning to operate like ants.
Abandoning pre-determined master plans
and instead focusing on smaller,
smarter decisions.
And it's not just the ants that we're learning from.
Bees are teaching us how to build honeycomb-style structures
providing maximum strength while using minimal materials.
Spiders are helping us design crawling robots
for inspecting ship hulls
and nuclear reactors.
Butterflies hold the key in their wings
to harnessing the sun's energy more efficiently than ever before.
And termites, with their unpowered air conditioning towers,
are inspiring architects.
It seems that arthropods really do have a lot to teach us.
Arthropods have been pivotal in shaping our culture
and distribution.
Without them, our food chains would collapse
and pests would multiply beyond control.
We humans would do well to remember
that arthropods could survive perfectly well without us.
But life as we know it could not continue without them.
Subtitles by Red Bee Media Ltd