0:00:02 > 0:00:04Our planet is the greatest living puzzle in the universe.
0:00:04 > 0:00:06A collection of worlds
0:00:06 > 0:00:08within worlds.
0:00:08 > 0:00:11Each one a network of relationships
0:00:11 > 0:00:13and connections
0:00:13 > 0:00:14between all their living parts
0:00:14 > 0:00:18leading to the diverse and complex world we live in.
0:00:21 > 0:00:23And at the heart of many of these worlds
0:00:23 > 0:00:25is a very special group of animals.
0:00:26 > 0:00:29The insects and their close relatives,
0:00:29 > 0:00:32the arachnids and crustaceans,
0:00:32 > 0:00:36classed together as the arthropods.
0:00:36 > 0:00:42Together, they account for 80% of all animal species on our planet.
0:00:42 > 0:00:44In these three specials,
0:00:44 > 0:00:47we're going to explore the connections and relationships
0:00:47 > 0:00:52that they have with us, our planet
0:00:52 > 0:00:53and with each other.
0:00:55 > 0:00:57Ultimately to understand how this group
0:00:57 > 0:01:00hold the key to life itself
0:01:00 > 0:01:03inside nature's microworlds.
0:01:11 > 0:01:14Humans evolved around 200,000 years ago
0:01:14 > 0:01:18into a world that was dominated by the arthropods.
0:01:22 > 0:01:25In that time, we've learnt to live alongside each other,
0:01:25 > 0:01:29taking the benefits and putting up with some of the annoyances.
0:01:31 > 0:01:34But do we understand what life would be like
0:01:34 > 0:01:36without this group of animals?
0:01:38 > 0:01:39How many of us really know
0:01:39 > 0:01:42how intricately linked our lives have become
0:01:42 > 0:01:45that, without the arthropods, life as we know it would not exist?
0:01:49 > 0:01:50Some even question
0:01:50 > 0:01:53if survival of the human race would be possible at all.
0:01:55 > 0:01:56But how can this be?
0:01:57 > 0:02:00What have the arthropods ever done for us?
0:02:04 > 0:02:08The ways they affect human life are diverse and far reaching
0:02:08 > 0:02:12and to really understand the importance of this influence,
0:02:12 > 0:02:14we need to unpick the relationships,
0:02:14 > 0:02:15both good and bad,
0:02:15 > 0:02:17that we have with the arthropods.
0:02:27 > 0:02:30One of the most intriguing ways they influence us
0:02:30 > 0:02:32occurs in the forests of Kenya.
0:02:42 > 0:02:45These driver ants are searching for food.
0:02:49 > 0:02:50They're efficient hunters
0:02:50 > 0:02:53moving through the forest like a tidal wave.
0:02:53 > 0:02:56They'll eat any living animal in their path.
0:03:00 > 0:03:03Colonies can number up to 22 million
0:03:03 > 0:03:06and it's said that even elephants will turn and flee
0:03:06 > 0:03:08when they see them coming.
0:03:09 > 0:03:12These lethal predators are actually totally blind.
0:03:14 > 0:03:19They rely on touch, smell and chemical signals to find their way.
0:03:22 > 0:03:25The soldiers flank the raiding columns of workers
0:03:25 > 0:03:27with immense jaws raised.
0:03:30 > 0:03:32Anything that can't outrun them
0:03:32 > 0:03:33risks becoming their prey.
0:03:37 > 0:03:39This is perhaps how most of us view arthropods -
0:03:39 > 0:03:42creepy crawlies that are nothing more than a problem.
0:03:46 > 0:03:47But their presence is actually
0:03:47 > 0:03:49a real asset for these villagers.
0:03:51 > 0:03:56The ants can capture up to 100,000 insects in a single raid,
0:03:56 > 0:03:59providing invaluable pest control for the farmers.
0:04:01 > 0:04:05Pests inside homes and in surrounding fields are removed,
0:04:05 > 0:04:07dismembered and devoured.
0:04:07 > 0:04:11In fact, the whole place is given a five-star ant clean-up.
0:04:18 > 0:04:21Thanks to their highly effective cleaning raids,
0:04:21 > 0:04:23these ants play a key role
0:04:23 > 0:04:25in the lives of the locals.
0:04:30 > 0:04:32But arthropods can provide us
0:04:32 > 0:04:35with something even more important than a service.
0:04:35 > 0:04:38They can provide us with one of the essential elements of life.
0:04:41 > 0:04:43900 miles south of Kenya
0:04:43 > 0:04:45lies Lake Malawi.
0:04:50 > 0:04:53Beneath the water, something's stirring.
0:05:01 > 0:05:07Trillions and trillions of lake fly larvae are getting ready to emerge.
0:05:13 > 0:05:17After many months buried in the sediment on the lake floor,
0:05:17 > 0:05:19they'll take to the air to mate.
0:05:24 > 0:05:28Towers of mating flies stretch hundreds of metres into the air.
0:05:31 > 0:05:33Like smoke, they rise
0:05:33 > 0:05:34from the surface of the lake.
0:05:40 > 0:05:44The towers of flies are swept by the wind towards the shore
0:05:44 > 0:05:46and towards human habitation.
0:05:49 > 0:05:51Here, they cloak vegetation
0:05:51 > 0:05:55and engulf whole forests and villages in their path.
0:06:00 > 0:06:02This may seem like an annoyance,
0:06:02 > 0:06:06but, actually, these flies present great opportunity.
0:06:14 > 0:06:17Villagers sweep baskets through the air to catch the flies.
0:06:20 > 0:06:24The biomass of these flies is equivalent to huge herds of game
0:06:24 > 0:06:26that roam the surrounding plains,
0:06:26 > 0:06:28but they're far easier to catch.
0:06:35 > 0:06:37The flies are then made into patties
0:06:37 > 0:06:39and fried in hot oil.
0:06:42 > 0:06:44Each patty contains half a million flies
0:06:44 > 0:06:48and has seven times more protein than the average beef burger.
0:06:50 > 0:06:52For people who have little protein in their diet,
0:06:52 > 0:06:53this can be a lifesaver.
0:06:57 > 0:07:00It may feel a long way from our idea of a perfect meal,
0:07:00 > 0:07:02but the importance of eating arthropods
0:07:02 > 0:07:04shouldn't be underestimated.
0:07:10 > 0:07:12Over 11 million tonnes of crustaceans
0:07:12 > 0:07:14are consumed by humans every year.
0:07:25 > 0:07:29In Botswana, the mopane worm collection industry
0:07:29 > 0:07:31is worth millions of pounds each year.
0:07:35 > 0:07:39For 2.5 billion people worldwide,
0:07:39 > 0:07:41insects are a vital source of food.
0:07:47 > 0:07:50More than a thousand insect species
0:07:50 > 0:07:52form a regular part of the human diet.
0:07:57 > 0:08:01Rich in vitamins, protein and minerals.
0:08:06 > 0:08:08It's mainly in the West
0:08:08 > 0:08:11that people are uncomfortable with the idea of eating insects.
0:08:14 > 0:08:16But the United Nations believe
0:08:16 > 0:08:19that eating insects instead of mammal meat
0:08:19 > 0:08:22may provide a solution to stamping out famine
0:08:22 > 0:08:23and reducing climate change.
0:08:28 > 0:08:30The raising of livestock such as cows, pigs and sheep
0:08:30 > 0:08:34occupies two thirds of the world's farmland
0:08:34 > 0:08:37and generates 20% of all greenhouse gases.
0:08:44 > 0:08:46With the human population projected to reach nine billion
0:08:46 > 0:08:48in just 40 years' time,
0:08:48 > 0:08:50the consumption of arthropods
0:08:50 > 0:08:53could provide a healthy Earth-saving measure.
0:08:56 > 0:08:59So, in the future, arthropods have the potential
0:08:59 > 0:09:02to address our global food crisis.
0:09:02 > 0:09:04That's no small claim.
0:09:06 > 0:09:10But they've also played an enormous role in shaping our past
0:09:10 > 0:09:13to such an extent that human life, as we know it,
0:09:13 > 0:09:17would not exist if it weren't for this next arthropod product.
0:09:20 > 0:09:23It all started with a cocoon
0:09:23 > 0:09:25and a beautiful piece of cloth.
0:09:30 > 0:09:32China - home to a billion people
0:09:32 > 0:09:35and a very special arthropod.
0:09:36 > 0:09:38This is a silk worm caterpillar.
0:09:41 > 0:09:43They eat only mulberry leaves.
0:09:45 > 0:09:47And, after 50 days of feeding,
0:09:47 > 0:09:51they'll be 10,000 times heavier and ready to transform.
0:09:54 > 0:09:5725% of their body mass is made up of silk glands.
0:10:01 > 0:10:04They spin a cocoon using a single thread
0:10:04 > 0:10:07which can be over 900 metres in length.
0:10:10 > 0:10:13And it's this silk that forms the basis of an industry
0:10:13 > 0:10:15that's shaped our history
0:10:15 > 0:10:17and today, has a commercial value
0:10:17 > 0:10:19of up to £300 million.
0:10:27 > 0:10:33The cocoons are boiled and precious silken threads begin to unwind.
0:10:37 > 0:10:41But this arthropod product is not only responsible for human clothing.
0:10:43 > 0:10:46It's shaped our culture for over a thousand years.
0:10:50 > 0:10:54The transport of silk from Asia towards Europe
0:10:54 > 0:10:58led to the establishment of the famed Silk Road around 200 BC.
0:11:01 > 0:11:03This 4,000-mile trade route
0:11:03 > 0:11:07forged relationships between different and diverse cultures.
0:11:09 > 0:11:11And was pivotal in the development of the civilisations
0:11:11 > 0:11:15in China, India, Europe and Arabia.
0:11:20 > 0:11:24So silk has shaped human culture and distribution,
0:11:24 > 0:11:28but there's another arthropod product that's valued so highly
0:11:28 > 0:11:31humans will risk their life trying to collect it.
0:11:37 > 0:11:39The Himalayas, in Nepal.
0:11:41 > 0:11:45These men are climbing 400 metres up sheer cliffs
0:11:45 > 0:11:47to steal from giant honey bees.
0:11:50 > 0:11:53They're the largest honey bee in the world
0:11:53 > 0:11:55and their stings are notoriously painful.
0:11:57 > 0:11:59So what could make men risk their lives in this way?
0:12:01 > 0:12:02Honey!
0:12:04 > 0:12:07These bees, like honey bees the world over,
0:12:07 > 0:12:09take nectar from the surrounding flowers
0:12:09 > 0:12:12and spit it into the cells in the comb.
0:12:16 > 0:12:19Enzymes in their saliva break down the sugars
0:12:19 > 0:12:22and water evaporates until the condensed honey remains.
0:12:25 > 0:12:27This honey will be the colonies' sole source of food
0:12:27 > 0:12:29during the colder winter months
0:12:29 > 0:12:32and they'll give up their lives to protect it.
0:12:34 > 0:12:38So the honey gatherers will not only have to deal with perilous heights,
0:12:38 > 0:12:40but also with angry bees.
0:12:43 > 0:12:46When the men finally reach the comb,
0:12:46 > 0:12:47they must manoeuvre sticks
0:12:47 > 0:12:49to work free a section of honey.
0:12:52 > 0:12:55With little protection against the stings,
0:12:55 > 0:12:58they must work quickly before being overcome by the bees venom.
0:13:03 > 0:13:06The honeycomb is dropped into a suspended basket
0:13:06 > 0:13:09and then lowered to the ground.
0:13:09 > 0:13:12They leave a large section of the comb intact
0:13:12 > 0:13:14so the colony can rebuild its honey supplies.
0:13:17 > 0:13:22Job complete, the men can descend to enjoy their hard-won prize.
0:13:24 > 0:13:27Honey's made up of 80% natural sugars
0:13:27 > 0:13:30and so, provides a vital energy-rich food source
0:13:30 > 0:13:31for these mountain dwellers.
0:13:33 > 0:13:36So prized is this product
0:13:36 > 0:13:40that the farming of arthropods for their honey has now gone global.
0:13:43 > 0:13:48Around 1.2 million tonnes of honey is produced worldwide each year.
0:13:48 > 0:13:51When you think that one little bee in its entire lifetime
0:13:51 > 0:13:54produces only about a spoonful of honey,
0:13:54 > 0:13:56that's a humbling amount of work
0:13:56 > 0:13:58from our arthropod friends.
0:14:02 > 0:14:06But honey isn't the only product that bees provide us with.
0:14:10 > 0:14:11Bees and their relatives
0:14:11 > 0:14:16have a much more far reaching and significant effect on us humans.
0:14:18 > 0:14:22Without which, it's questionable if humans would survive at all.
0:14:27 > 0:14:29And to see what this is,
0:14:29 > 0:14:33we must examine a wonderful process happening all around us
0:14:33 > 0:14:36and responsible for shaping the world we live in.
0:14:40 > 0:14:42The coastal cliffs of Sardinia,
0:14:42 > 0:14:43in the Mediterranean,
0:14:43 > 0:14:45are home to an unusual plant.
0:14:48 > 0:14:49The dead horse arum.
0:14:50 > 0:14:53It looks like a dead rotting animal
0:14:53 > 0:14:54and has a smell to match.
0:14:56 > 0:14:58This canny flower even raises its temperature
0:14:58 > 0:15:02by as much as 20 degrees above the surrounding vegetation
0:15:02 > 0:15:04to complete its disguise.
0:15:07 > 0:15:09The smell is taken by the wind
0:15:09 > 0:15:12and it's not long before the arum is noticed.
0:15:14 > 0:15:16These flies are hoping they've found a carcass
0:15:16 > 0:15:17on which to lay their eggs,
0:15:17 > 0:15:19but, instead, they become trapped.
0:15:21 > 0:15:22Inside the flower,
0:15:22 > 0:15:24they brush against the female stigma
0:15:24 > 0:15:27releasing any pollen they're already carrying.
0:15:28 > 0:15:31This flower is now pollinated.
0:15:36 > 0:15:40Spines prevent the flies' escape and they're trapped.
0:15:44 > 0:15:47Overnight, when the flies are inactive,
0:15:47 > 0:15:50the spines wither and the male pollen above them ripens
0:15:50 > 0:15:52ensuring that, in the morning,
0:15:52 > 0:15:55each exiting fly is coated with pollen to take to the next flower.
0:16:00 > 0:16:03This flower has invested everything
0:16:03 > 0:16:05in the process of cross-pollination.
0:16:05 > 0:16:06It's modified its appearance,
0:16:06 > 0:16:09its smell, its temperature
0:16:09 > 0:16:11and its internal barriers,
0:16:11 > 0:16:14all to ensure the transfer of pollen grains
0:16:14 > 0:16:16from one plant to another.
0:16:24 > 0:16:26And it's this process of pollination
0:16:26 > 0:16:28that's the next key
0:16:28 > 0:16:31to why the arthropods are pivotal to human success
0:16:31 > 0:16:33and to our very own food chain.
0:16:37 > 0:16:40As much as 35% of all human food
0:16:40 > 0:16:43is dependent on pollination by arthropods.
0:16:46 > 0:16:50Across the world, the value of crops pollinated by insects
0:16:50 > 0:16:54is over £120 billion a year.
0:16:54 > 0:16:59Without them, we wouldn't have apples, almonds, cherries, oranges,
0:16:59 > 0:17:01tomatoes or squash on our supermarket shelves.
0:17:04 > 0:17:0684% of crop species grown in Europe
0:17:06 > 0:17:09still depend on insect pollination.
0:17:11 > 0:17:14Without insects, our crops would flounder,
0:17:14 > 0:17:16supermarket stocks would plummet
0:17:16 > 0:17:19and life on Earth would irreversibly suffer.
0:17:23 > 0:17:27But to really understand our relationship with the arthropods,
0:17:27 > 0:17:30we need to examine their negative effects as well as the positive.
0:17:33 > 0:17:35The deserts of West Africa.
0:17:41 > 0:17:44Moisture in the soil and increased temperatures
0:17:44 > 0:17:46provide the triggers for a mass hatching.
0:17:49 > 0:17:51Eggs that may have lain dormant for 20 years hatch
0:17:51 > 0:17:55and flightless locusts, called hoppers emerge.
0:17:58 > 0:18:03These hoppers follow the smell of freshly sprouting grass.
0:18:03 > 0:18:05After about 20 days of feasting,
0:18:05 > 0:18:09they transform into winged adults and form a swarm.
0:18:12 > 0:18:15A swarm can cover an area of 1,000 square miles
0:18:15 > 0:18:17and can literally blot out the sun.
0:18:23 > 0:18:26They eat their own body weight in food each day.
0:18:29 > 0:18:33En masse, they can get through 200,000 tonnes of crops,
0:18:33 > 0:18:35enough to feed half a billion people.
0:18:45 > 0:18:49Many arthropods have the potential to reach biblical proportions.
0:19:01 > 0:19:05Their ability to reproduce quickly and prolifically
0:19:05 > 0:19:08means their numbers, left unregulated,
0:19:08 > 0:19:09can snowball out of control.
0:19:13 > 0:19:16For us humans, that can present a real problem.
0:19:22 > 0:19:26And there's a parasite that's utilised this breeding success
0:19:26 > 0:19:30and today, it's the biggest cause of human fatality on our planet.
0:19:40 > 0:19:43It kills 3,000 people every day
0:19:43 > 0:19:46and without arthropods, it wouldn't exist.
0:19:47 > 0:19:49Throughout history,
0:19:49 > 0:19:53this relentless killer has claimed more victims than any other disease.
0:19:55 > 0:19:58It's killed more people than both the world wars put together
0:19:58 > 0:20:02and at least 40% of the world's population are at risk.
0:20:06 > 0:20:08The disease is carried by the Anopheles mosquito
0:20:08 > 0:20:10and it's called malaria.
0:20:13 > 0:20:15But, really, this mosquito
0:20:15 > 0:20:17is just a pawn in a parasite's game.
0:20:20 > 0:20:23The parasite lives by eating the red blood cells
0:20:23 > 0:20:24of the victim it attacks.
0:20:26 > 0:20:29When a mosquito bites an infected person,
0:20:29 > 0:20:32it sucks up the blood containing the parasite into its gut.
0:20:34 > 0:20:36The parasite multiplies...
0:20:39 > 0:20:42..then, burrows into the mosquito's saliva gland...
0:20:45 > 0:20:46..where it's squirted into the blood
0:20:46 > 0:20:48of the mosquito's next victim.
0:20:52 > 0:20:54And so, the cycle continues.
0:20:56 > 0:20:58But can we really blame the mosquito?
0:21:01 > 0:21:04It gains nothing from carrying the parasite.
0:21:09 > 0:21:11And, ironically, mosquitoes,
0:21:11 > 0:21:13along with other arthropods,
0:21:13 > 0:21:16might be the ultimate solution to this deadly disease
0:21:16 > 0:21:19in their ability to regulate each other.
0:21:28 > 0:21:30An example of this is played out
0:21:30 > 0:21:32in a field in the South Downs.
0:21:36 > 0:21:40These aphids are doing what aphids do best -
0:21:40 > 0:21:42multiplying.
0:21:46 > 0:21:48They're breeding machines
0:21:48 > 0:21:49and, by the end of a season,
0:21:49 > 0:21:53a single aphid can have produced over a billion descendants.
0:22:04 > 0:22:07Each aphid uses their specialised mouth parts
0:22:07 > 0:22:10to suck out the plants' juices.
0:22:10 > 0:22:13Left uncontrolled, they can devastate a whole field of crops.
0:22:17 > 0:22:19Luckily for farmers and gardeners,
0:22:19 > 0:22:22there's a crack team of predators on standby.
0:22:25 > 0:22:28Firstly, the colourful but ferocious ladybird.
0:22:33 > 0:22:37One ladybird can eat over 5,000 aphids in a lifetime.
0:22:39 > 0:22:41But working alone, they'd have their work cut out
0:22:41 > 0:22:44to keep up with the prolific breeding of the aphids.
0:22:45 > 0:22:47Luckily, they've got backup.
0:22:49 > 0:22:53Money spiders parachute in from surrounding fences and hedgerows.
0:22:57 > 0:23:00The spiders spin delicate but lethal orb webs
0:23:00 > 0:23:02and wait for their prey to arrive.
0:23:08 > 0:23:10When the bumbling ladybird has had her fill,
0:23:10 > 0:23:13her movements dislodge further aphids
0:23:13 > 0:23:15that drop into the silken traps below.
0:23:16 > 0:23:19This natural balance of predators and prey
0:23:19 > 0:23:22may seem only relevant to gardeners and farmers,
0:23:22 > 0:23:26but the global importance of this natural biological control
0:23:26 > 0:23:27is not to be underestimated.
0:23:31 > 0:23:34Pest control services provided by insects were valued
0:23:34 > 0:23:37at over 60 billion dollars a year, in the USA alone.
0:23:39 > 0:23:42This is a service we really can't afford to lose.
0:23:49 > 0:23:53And the arthropod regulators could potentially provide some hope
0:23:53 > 0:23:56against the worst disease the human race has ever faced.
0:24:00 > 0:24:03There are plans for a non-malaria-carrying mosquito
0:24:03 > 0:24:07to be released to outcompete the deadly malaria-carrying ones.
0:24:11 > 0:24:15So we've seen how arthropods provide us with food and products.
0:24:15 > 0:24:19How they've shaped our distribution and culture.
0:24:19 > 0:24:22We've seen how pivotal they are to our own food chain
0:24:22 > 0:24:27and how their presence can regulate pests and even fatal diseases.
0:24:29 > 0:24:33But there's one final key to how they influence our lives...
0:24:35 > 0:24:37..one final offering from the arthropods
0:24:37 > 0:24:40that could shape the way we exist and operate in years to come.
0:24:52 > 0:24:54In this vast colony,
0:24:54 > 0:24:58every army ant appears to be following a master plan,
0:24:58 > 0:25:01like tiny cogs in a huge machine.
0:25:05 > 0:25:09They allocate resources depending on environmental conditions.
0:25:12 > 0:25:15If a rich food source is found,
0:25:15 > 0:25:17workers will appear to deal with the bounty.
0:25:25 > 0:25:28They build organised highways with no congestion.
0:25:31 > 0:25:35They construct shelter and a place to rear their young
0:25:35 > 0:25:37using their own bodies.
0:25:39 > 0:25:41They stage foraging raids
0:25:41 > 0:25:44and vacate an area of forest when food sources dwindle.
0:25:46 > 0:25:49They're efficient, responsive and smart.
0:25:49 > 0:25:52Everything our human organisations strive to be.
0:25:55 > 0:25:57But this colony doesn't function
0:25:57 > 0:25:59like any organisation we humans are familiar with.
0:26:03 > 0:26:06There's no central control, no figure of authority.
0:26:06 > 0:26:08The queen ant may have her lofty title,
0:26:08 > 0:26:10but plays no role in coordination.
0:26:15 > 0:26:19And we're just starting to learn how such efficiency is achieved.
0:26:26 > 0:26:31Haulage companies and airports are learning to operate like ants.
0:26:34 > 0:26:37Abandoning pre-determined master plans
0:26:37 > 0:26:39and instead focusing on smaller,
0:26:39 > 0:26:41smarter decisions.
0:26:42 > 0:26:45And it's not just the ants that we're learning from.
0:26:47 > 0:26:51Bees are teaching us how to build honeycomb-style structures
0:26:51 > 0:26:55providing maximum strength while using minimal materials.
0:26:55 > 0:26:59Spiders are helping us design crawling robots
0:26:59 > 0:27:01for inspecting ship hulls
0:27:01 > 0:27:02and nuclear reactors.
0:27:05 > 0:27:07Butterflies hold the key in their wings
0:27:07 > 0:27:11to harnessing the sun's energy more efficiently than ever before.
0:27:14 > 0:27:18And termites, with their unpowered air conditioning towers,
0:27:18 > 0:27:20are inspiring architects.
0:27:24 > 0:27:28It seems that arthropods really do have a lot to teach us.
0:27:31 > 0:27:35Arthropods have been pivotal in shaping our culture
0:27:35 > 0:27:36and distribution.
0:27:40 > 0:27:44Without them, our food chains would collapse
0:27:44 > 0:27:47and pests would multiply beyond control.
0:27:58 > 0:28:01We humans would do well to remember
0:28:01 > 0:28:04that arthropods could survive perfectly well without us.
0:28:06 > 0:28:12But life as we know it could not continue without them.
0:28:45 > 0:28:48Subtitles by Red Bee Media Ltd