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00:00The ability to move through the air in any direction you wish, to cross continents and oceans, to range over forests and deserts and mountains,
00:28all this birds have been able to do for 150 million years, but they weren't the first, or indeed the last, in the skies.
00:40We are setting out to explore one of the most astonishing stories in the natural world.
00:47The way in which animals manage to rise up from the surface of the earth and colonize the air.
00:56From the dazzling aerobatics of the insects,
01:02to the majesty of ancient winged reptiles.
01:13The splendor and agility of birds.
01:16And the sonar-guided precision of night-flying bats.
01:28Flight has been the key to the success of some of our planet's most remarkable inhabitants.
01:34To analyze their spectacular skills, we will use the latest technology.
01:50And we will travel around the world.
01:53From the jungles of Borneo to the fossil-filled rocks of China.
01:57And the cloud forests of Ecuador.
02:06We will take you into the air.
02:11And travel with animals as they fly.
02:13As they fly.
02:14As they fly.
02:15As they fly.
02:21As they fly.
02:29As they fly.
02:43this astonishing story can be found close to home in the fens of cambridgeshire
02:51here live creatures that have an ancestry stretching back millions of years
02:59nobody knows exactly how the first flying animals in the world evolved but there are
03:05creatures alive today that can take us back to those far distant remarkable times and they live
03:12surprisingly underwater looking down through the surface to the river bed is like traveling back
03:25in time over 320 million years it was then in an age long before even the dinosaurs evolved
03:36that creatures like this first appeared in the waters of the earth
03:45it's an insect
03:48a ferocious predator with jaws like a mechanical grab
03:52it seems unlikely but this animal's ancestors were among the first creatures ever to fly
04:10but this one is not yet adult it's a larva and it doesn't spend all its life in the water
04:24it has another life and another body above the surface
04:28a split appears in its skin and a very different looking creature begins to emerge
04:47it has four lumps on its back that might perhaps ancestrally have become either gills
04:53or protective armor plates
04:57but now they develop into something very different
05:06wings
05:10it has two pairs of them
05:14liquid from its body is pumped down along veins to stretch them tight
05:19as they dry in the sun they harden
05:34the water living dragon has become the dragonfly
05:39and the four-winged apparatus that it uses to get into the air is the earliest that we know
05:49we've been able to find the next to the river
05:50imprints of such wings have been found in rocks that
05:53were laid down on the bottom of ancient lakes and streams
06:00this specimen is about a hundred and fifty million years old
06:05and at nearly three hundred million years
06:08this is the oldest complete wing yet discovered
06:11Ancient and modern wings share a structure that is strikingly similar.
06:23So today's dragonflies are amazingly living fossils
06:27that can show us how the very first flyers
06:30overcame the pull of gravity and took to the skies.
06:41The wings are marvels of natural engineering.
06:48But to see how they lift a dragonfly into the air,
06:52we need to slow the action down.
06:55The wings are marvels of natural engineering.
07:00But to see how they lift a dragonfly into the air,
07:04we need to slow the action down.
07:07In principle, it looks fairly simple.
07:10Each wing beats down, pushing on the air below,
07:13so lifting the dragonfly up.
07:16But each beat also creates another air current
07:19that lifts the dragonfly in a very different way.
07:22And I can demonstrate it using this strip of paper
07:26to represent a wing.
07:28If I blow across the top of it,
07:30it will reach the dragonfly in a very different way.
07:33And I can demonstrate it using this strip of paper
07:36and on top of it, it'll rise. Watch.
07:48That is because the faster air moves,
07:51the lower its pressure.
07:53So I created a lower pressure above the wing,
07:56and in consequence, it was sucked upwards.
07:59The problem for a flying animal
08:01is to recreate that difference in air speed.
08:13The way the dragonfly does this is remarkable.
08:16As it moves through the air,
08:21we can see that it twists its wings at different angles.
08:28On the powerful downbeat,
08:32it holds them at a slight upwards angle to the airflow.
08:36And this produces an extraordinary effect above the wing.
08:40It creates a swirl behind the leading edge,
08:45which spins the air round,
08:47increasing the speed of the air current
08:49over the top of the wing.
08:51And just a tiny increase in speed
08:54generates a significant upwards force,
08:57lifting up the wing and the dragonfly.
09:01The dragonfly can then change the direction of its wing beats
09:08to propel it forwards as well as upwards.
09:18Remarkably, a dragonfly can beat each of its four wings independently.
09:23And that enables it to perform an astonishing variety of maneuvers.
09:33It can hover.
09:38It can glide.
09:42It can even fly backwards.
09:44From maximum power, it beats both pairs together
09:53and can make really sharp turns.
09:59So the very first dragonflies
10:01were able to extend their territories far and wide.
10:08And as more insects joined them in the skies,
10:11the dragonflies had the skills to be deadly aerial hunters.
10:32The ability to fly brought great advantages to those early insects.
10:36It enabled them to find food,
10:38to escape from predators.
10:40And particularly important,
10:41to travel to new territories in search of a mate.
10:50Camselflies, like their close relations dragonflies,
10:53have remained virtually unchanged for millions of years.
10:58Mating can be quite complicated when both partners can fly.
11:03And these were among the first kind of animals
11:05that had to deal with that problem.
11:07The blue color of this one shows that it's a male.
11:12To attract a female, a male must have something to offer her.
11:17A territory.
11:19He chooses a stretch of water that is likely to contain plenty of food for his offspring.
11:30Then he guards this territory against any rivals.
11:36Until a female flies in and joins him.
11:39He must now grab her before she changes her mind, in mid-air if necessary.
11:49He uses claspers at the tip of his abdomen to grip her behind her neck.
11:55Amazingly, the pair are able to coordinate the beats of their eight wings.
12:01They may mate in the air or choose a secluded perch,
12:06where they'll be safe from predators.
12:10They then fly around the territory, laying their fertilized eggs.
12:14Flight enabled insects to invade part of the planet that until then had been uninhabited.
12:32The air.
12:34And they flourished.
12:39So, 320 million years ago, the skies thronged with flying insects.
12:46But those early four-winged forms were destined to produce a whole range of spectacular, highly specialized fliers.
12:54The need to lay eggs in water tied the first dragonflies to streams and ponds like these.
13:07But then, around 20 million years after their arrival,
13:11a new kind of flying insect appeared with no such ties to water.
13:16To find spectacular proof of their success, we're headed next to Borneo.
13:22To find the next chapter in our evolutionary story of the flying insects, I've come to Borneo.
13:46The very first flyers had two pairs of wings.
13:52Now, we're looking for their successes.
13:55One group of creatures adapted that original four-wing design with such success that they diversified into the most numerous and widespread group of animals on the entire planet.
14:09And you can find some of the most spectacular examples down there in the rainforest.
14:15Not all insects are hunters.
14:16Some are strict vegetarians, like this one.
14:25This is the land-living equivalent of that underwater monster, the dragonfly larva.
14:35But this larva, instead of cutting little fish and water fleas, munches wood pulp.
14:45The trouble is that wood pulp is not very nutritious.
14:48And this creature has to eat it for at least a year before it's this size, which is full-grown.
14:55But then this larva will turn into an adult, which is equally monstrous.
15:07Emerging from beneath the ground where it has lived and fed as a larva is a beetle, one of the biggest in the world.
15:28The Atlas beetle.
15:37Males like this one are armed with long horns, powerful weapons with which to compete with rivals for a mate.
15:46It now spends most of its time above the ground, barging its way through the undergrowth, where it feeds on tree sap and fallen fruit.
15:58This hefty, powerful creature may not look as if it could fly, but it can.
16:07At key moments in its life, it takes to the air to look for new sources of food and, of course, a female.
16:19All this burrowing and rumsing around could injure delicate flight wings.
16:33So beetles have hardened the front pair to form this pair of protective covers.
16:39And the delicate flight pair are stowed away in safety underneath.
16:54To see how the wings are folded away beneath their covers, we need to wait for takeoff.
16:59As it flaps, sprung hinges click open and the wings are stretched to their full size.
17:16The working wings create lift in just the same way that the dragonflies wings do.
17:38And the front wings, which have now become covers, are held out to the side.
17:48And their shape does give a little extra lift.
17:52But it's clear that this is really a clumsy fly.
17:55Clumsy fly.
18:03Landings can be clumsy too.
18:07And now those fragile wings must be carefully packed away beneath their covers.
18:14They're guided by a line of tiny hairs at the base of the abdomen.
18:18These grip the wings and help push them into position.
18:28The beetle does it with all the care and precision that a skydiver uses
18:33when packing away his parachute.
18:39Once in a new territory, it will stake out a fresh source of food
18:43and then defend it until a female arrives.
18:51The beetle way of life proved astonishingly successful.
18:55There are over 370,000 different species of beetle so far discovered.
19:01Unbelievable figure.
19:04So, early on, the beetles managed to fly as much as they need to
19:10with just one pair of wings.
19:14And then, around 57 million years ago, came another key development
19:21in the history of flight.
19:27A new type of insect appeared, with two pairs of wings
19:32that became, in effect, huge billboards.
19:35Wings that are perhaps the most dazzlingly beautiful of all.
19:39Butterflies.
19:40Butterflies.
20:00Butterflies live on nectar, which they collect from flowers.
20:04Like dragonflies and beetles, they also fly to find a mate.
20:09But the way they beat their colorful wings is significantly different.
20:13This lovely creature has two pairs of wings, but it has, in effect, turned them into one.
20:22It's done that quite simply by overlapping the larger front pair over the smaller hind pair, so that when the front pair beat down, they automatically press down the lower pair.
20:36The lower pair themselves don't have the muscles to beat down, but just enough strength to return up.
20:54A butterfly's overlapping wings, compared to the size of their bodies, are enormous, around ten times the size of other insect wings.
21:09Because the wing is larger, each beat can generate a huge amount of lift.
21:25So, to stay airborne, a butterfly needs to flap less often than other insects.
21:31But that slow wing beat also enables it to make rapid and unpredictable changes of direction.
21:42And that allows butterflies to fly in that zig-zag, erratic way, which makes them so difficult to catch if you're a butterfly collector, or more importantly, a predator.
21:52The combined front and hind wings of a butterfly not only constitute very effective flying mechanism, they can also carry messages.
22:18In fact, they carry some of the loveliest advertisements in the whole of the animal kingdom.
22:24Like, for example, this beautiful golden birdwing butterfly from Borneo.
22:33The butterfly's huge wings provide a spacious canvas on which to display fantastically elaborate designs.
22:41So, how are these flying advertisements created?
22:47The secret lies in the microscopic structure of the wing's surface.
22:58These overlapping scales, lined up like tiles on a roof, have evolved from bristles that were once tiny sensors.
23:06Some contain tiny packets of pigment that give the wings color.
23:22Others have a complex structure which splits the light so that when viewed from a particular angle, it reflects a brilliant iridescence.
23:31There are over 18,000 species of butterfly around the world, and each has wings with their own distinctive design.
23:51These ravishing colors and delectable patterns, of course, enable a male butterfly and a female butterfly to know whether or not they belong to the same species.
24:04And a mature adult, ready to mate, can identify a suitable partner from surprising distances.
24:11When a male and female eventually meet, they flutter around each other in a ritual dance.
24:29Each is checking out the flying skills and wing patterns of the other.
24:32If both pass the test, they mate.
24:43The sheer size of butterfly wings might seem to condemn their owners to a slow, almost dawdling flight.
25:02But they can be much more efficient aeronauts than you might suppose.
25:06Butterflies may not be able to fly very fast, but astonishingly for such frail-looking creatures, they can travel for hundreds of miles in search of food.
25:19New discoveries are revealing that butterflies make immense journeys.
25:28And one of the most exciting of these studies is taking place 7,000 miles west of Borneo in Europe.
25:35I am joining a research project in the upland meadows of central Spain to look for one of the greatest of all butterfly travelers.
26:00The Painted Lady.
26:05Every spring, painted ladies appear in Spain in great numbers.
26:12But Spain is just a stopover.
26:18An international team of scientists are uncovering evidence of an astonishing journey right across Europe and beyond.
26:26This hugely ambitious project is the brainchild of Dr. Constante Stefanescu.
26:36Detailed records of when and where painted ladies appear have revealed an extraordinary mass migration.
26:55We were able to collate a huge number of observations from more than 60 different countries and maybe 35,000 records.
27:10Many people contributing their observations.
27:14And for the first time it was possible to understand the general pattern of migration all year round.
27:21By combining this wealth of data, the team are revealing a route map that spans incredible distances.
27:31And it begins in North Africa.
27:33Large numbers of painted ladies breed in Morocco over the winter before setting out across the Mediterranean to Europe.
27:46They then follow the spring bloom north as the plants that they and their young feed on sprout leaves and flowers.
27:52In summer, they appear in Britain and Scandinavia.
27:59But no individual butterfly lives long enough to achieve this huge journey by itself.
28:05Each step is taken by a new generation.
28:08So this painted lady in Britain is the grandchild of a butterfly that set out from Morocco.
28:21But then in autumn, all the painted ladies vanish.
28:25Do they simply die out or could there be a return leg to their epic migration?
28:35Searching for an answer to this mystery has given the project its most astonishing revelation yet.
28:41And it comes from a part of the team based at Rothensted Research Institute just outside London.
28:50The key discovery emerged from a surprising source.
28:55Radar.
28:56Our radar has a vertical pointing beam and it illuminates a narrow column of the sky above, like shining a powerful spotlight up into the sky.
29:09And we're able to detect individual insects as they fly through that beam.
29:13The signal is so detailed it can even help identify the species.
29:18And during the autumn disappearance, the radar picked up large numbers of painted ladies.
29:26They weren't dying out.
29:28They were on the move.
29:30And they were flying at astonishing heights.
29:33What we found was, in fact, the painted ladies were highly abundant at heights of three, four, five hundred meters above the ground.
29:40At this great height, they were invisible to observers down below.
29:48This explained their disappearance.
29:51But the butterflies had their own very good reasons to travel at such altitudes.
29:57One of the benefits of flying at three or four hundred meters above the ground is that the wind speeds there are much faster than they are at ground level.
30:04So the insects are able to get a lot of assistance from the wind and travel much faster than they would under their own powered flight.
30:11And we see these painted ladies traveling at 50 or even 70 miles an hour.
30:18As well as measuring the phenomenal speed of their flight, the radar also revealed its direction.
30:25They were heading south.
30:29So where were they going?
30:30The astonishing answer came from Constanti's far-flung network of observers.
30:39And the crucial piece of data was gathered in Africa.
30:43Some expeditions in Africa in October, November have shown that there is a huge arrival of butterflies at that moment.
30:50So by the end of the summer, the newborn butterflies in Europe start to migrate way back to Africa.
31:00Really?
31:01Yeah.
31:03A final generation riding on high-altitude winds makes an immense journey of up to 3,000 miles to West Africa in just a matter of days.
31:13Observers on the ground and radar in the air had found proof of an amazing migration cycle.
31:23Just in one year, the whole cycle is made and is the succession of these six generations moving about 5,000 kilometers in one direction and 5,000 in another direction.
31:38This migration is in fact the longest made by any insect on the planet so far discovered.
31:49Some insects face a very different challenge.
31:52Not flying long distances, but flying in the dark.
31:56A light trap can attract some of the most remarkable of these nocturnal flyers.
32:20Moths.
32:30Moths probably evolved to fly at night to avoid predators.
32:35Their eyes are adapted to low light, but they also use a second highly developed sense, smell.
32:42This is a male moon moth.
32:49Moths overlap their two pairs of wings in just the same way as butterflies do.
32:55And this particular moth is very special.
32:58It has an extremely short life.
33:01It will only live for a week.
33:03It won't even feed.
33:05Its only object is to find a female.
33:10And it does that with these remarkable feather-like antennae.
33:18The female emits a particular characteristic scent.
33:22And with those antennae, the male can sense it from as much as a mile away.
33:28It then takes off and flies upwind until eventually it finds the source.
33:43Moths, with their combined front and rear wings, are also excellent flyers.
33:48Some live longer and so need to fly to find food.
33:57This sphinx moth's favorite food is nectar.
34:03It can even hover as it drinks.
34:05So by overlapping their two pairs of wings, butterflies and moths have become very competent flyers.
34:22But there's one group of flying insects that has changed the back pair of wings into something quite, quite different.
34:30Something that enables them to perform the most extraordinary aerial gymnastics.
34:46For the final chapter in our story of flying insects, I'm returning to London.
34:51The urban jungle and its human inhabitants provide plenty of shelter and food for a particularly adaptable and numerous kind of insect.
35:04Thank you very much.
35:09An inviting meal like this one will, I'm quite sure, very soon attract a flying diner
35:15that is one of the most remarkable of all insect aeronauts.
35:23It is, of course, a fly.
35:26This particular kind, a blowfly, occurs all over the world.
35:31And its ancestors have been buzzing around for at least 250 million years.
35:36Flies are so common, we tend to dismiss them as just irritating pests.
35:45But their flying abilities are truly remarkable.
35:49Watch what happens if I try and spot this one with the menu.
35:58Slowing down the action by 40 times, we can see how astonishingly agile flies are.
36:03It makes its escape in the time it takes me to blink my eye.
36:16The ability to twist and turn at such high speeds, and so evade enemies,
36:21has made flies the global success that they are.
36:23They are the jet fighters of the insect world.
36:34And they own their maneuverability not to the shape of their wings,
36:38nor the power of their muscles,
36:40but to a set of highly advanced flight sensors.
36:43A fly has its own version of a fighter pilot's instrument panel.
36:54Providing constant updates on speed, altitude, and direction of travel.
37:04A fly gathers this flight data through its eyes.
37:07And these are among the best in the business.
37:11They can process visual information around ten times as fast as our own eyes.
37:18But in high-speed maneuvers, even a fly's eyes struggle with one crucial piece of flight data.
37:27The angle of its body in the air and the way it changes.
37:31Information that a human pilot would get from an instrument based on a gyroskin.
37:40And that is essential if you're going to pull off a stunt like this one.
37:45Fortunately, flies not only have eyes to guide them.
37:58They also have a second and even more remarkable set of sensors.
38:04One that is derived from that original four-wing design.
38:08A fly only has a single pair of wings.
38:19The rear pair have been converted into something else.
38:23A tiny club-like appendage known as a halt ear.
38:28This surprisingly sophisticated organ alerts the fly to changes in the position of its body in the air.
38:36As the fly takes off, each halt ear begins to beat up and down.
38:43And so fast, it immediately becomes a blur.
38:49But in slow motion, we can see that it swings back and forth like a pendulum.
38:55To understand how the halt ear works, we need to track its movement in a mid-air role.
39:02The weighted tip of the halt ear has a kind of moving inertia.
39:10So that it remains on the same swinging path as the fly banks.
39:16Now, the angle between the body and the halt ear changes and the base is put under strain.
39:21This triggers sensors which register the role.
39:31The fly can then adjust its wing beat to correct any imbalance, however extreme.
39:37New studies into a second remarkable use of the halt ear signal are taking place at London's Imperial College.
39:47In the Department of Bioengineering, experts are studying blowflies to see if their natural flight mechanics can improve the performance of man-made flyers like this drone.
40:03Flies are incredibly maneuverable.
40:09And if you look at their performance, one chasing another one, it's really hardly any other animal that can match this sort of aerodynamic performance.
40:19Holger has devised an experiment to investigate an intriguing connection between a fly's halt ears and its other key flight sensor, its eyes.
40:32A tiny motor simulates a series of high-speed mid-air roles.
40:42The way the fly then reacts is recorded on a specialist camera which can replay the action in slow motion.
40:50As you can see, if you look closely, the head of the fly is maintained level.
40:58The body is rotating, and to maintain a level gaze, they have to counter-rotate the head.
41:05Keeping the eyes level is vital if they are to gather accurate flight information.
41:11And the halt ears have been identified as the crucial sensor that makes this possible.
41:15The visual system alone would just be too slow.
41:20That's where actually the halt ears come in.
41:22The halt ears are extremely fast in terms of their responses.
41:26And their immediate, well, signals that are then sent to the neck motor system and to the flight motor system,
41:35they are the first, really, to compensate for any disturbances.
41:38And if that has happened, the visual system is perfectly well situated to cope with the rest.
41:49So, flies lost a pair of wings, but gained an extraordinary new flight sensor
41:55that made them the most advanced flyers in the insect world.
41:58Flight has enabled the insects as a whole to become an astonishing global success.
42:11There are twice as many insect species than there are of all other animals put together.
42:18Theirs is a remarkable evolutionary story that spans over 320 million years.
42:25from the first four-wing creatures that emerged from the water
42:31to the armor-plated beetles which colonized land away from water.
42:38The butterflies with their huge, colorful wings.
42:41And the stunningly skillful aerobatic flies.
42:50But skill may not be enough.
42:52Sometimes sheer size counts.
42:55The insects had the skies for themselves for around 100 million years.
43:01But then a new group of animals appeared, animals that could build bigger bodies.
43:05bigger bodies.
43:06And they were to lift the techniques of flying to even greater heights.
43:14As our journey through time continues,
43:17we encounter the extraordinary pioneers of a new wave of larger flyers.
43:21monsterous winged reptiles.
43:31Strange feathered dinosaurs whose ventures into the air led to the birds.
43:40And a group of mammals that conquered the pitch black of the night.
43:43the bats.
43:45And join Sir David Attenborough next Thursday at 8,
43:46where he'll be getting a lesson in flying from a small flock of hooperswans in Scotland,
43:50as Conquest of the Skies continues on Skywind HD and Sky 3D.
43:54Next, Agatha Raisin, The Quiche of Death.
43:56And join Sir David Attenborough next Thursday at 8,
43:59where he'll be getting a lesson in flying from a small flock of hooperswans in Scotland,
44:03as Conquest of the Skies continues on Skywind HD and Sky 3D.
44:08Next, Agatha Raisin, The Quiche of Death.
44:09Agatha Raisin, The Quiche of Death.