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00:00Life has been evolving on planet Earth for three and a half billion years.
00:21Natural selection has shaped creatures to survive in nearly every habitat on the planet.
00:30And in the last few decades, humans have found that solutions to many of our technology problems are just waiting to be discovered in the vast library of life.
00:50In this program, we see how animals are locked in an evolutionary arms race.
00:56What can we learn from this?
00:58How is the flight of an owl connected to a beach in the Caribbean?
01:03How does a cuttlefish help the army to make a tank disappear?
01:11And how do horseshoe crabs give hope to someone who is paralyzed?
01:25There's a continual battle between predator and prey. Between trying to eat and trying not to be eaten. An arms race.
01:43As each evolves attack or defense mechanisms to survive.
01:46The arms race started in the distant past. These creatures live more than 500 million years ago.
01:52When there seemed to be a sudden increase in the variety of life.
01:55And among these new life forms were predators. New forms of attack.
02:00And there seemed to be a sudden increase in the variety of life.
02:04And among these new life forms were predators. New forms of attack.
02:09led to new forms of defense. And one simple defense is to wear a hard exterior. An exoskeleton.
02:34Trilobites are among the first creatures to have an exoskeleton.
02:43Perhaps the threat from predators drove their evolution.
02:47As predators become more sophisticated, armor becomes more elaborate.
02:52But the exoskeleton had other advantages. It changed life on Earth forever.
03:13It allowed ancient creatures to leave the safety and support of the water and crawl onto land.
03:20Every year, that moment in evolution is re-enacted along the eastern coast of North America.
03:34These are the nearest living relatives of trilobites. Horseshoe crabs.
03:49They're unchanged for nearly 200 million years. And emerge from the sea during spring tides. The highest tides of the month.
04:00An exoskeleton is waterproof. So that they don't lose water by evaporation.
04:13They lay their eggs in the sand, on the high tide mark, away from the water's edge.
04:20The eggs will hatch in two weeks, just in time for the next spring tide to wash the young crabs back into the sea.
04:35Another advantage of the exoskeleton is that it acts as a suit of armor.
04:45Not many predators can break through the hard shell.
04:50Eggs in the sand have no defense. The birds gorge themselves.
04:54But they can't attack the crabs. And an exoskeleton is strong.
05:03This is because a hollow cylinder is more rigid and yet lighter than a solid rod of the same material.
05:10So as armor and support, an exoskeleton is very efficient.
05:21Rigid cylinders, with muscles inside, make tiny creatures like ants incredibly strong for their body size.
05:29These are leafcutter ants. These ants are only a centimeter or so long, but carry a piece of leaf ten times their body weight over long distances to their nest.
05:44Wouldn't it be great if humans could be as strong as ants?
05:48But it doesn't work like this. There's a limit to how big a creature with an exoskeleton can get.
06:07As a creature gets bigger, its exoskeleton has to get thicker to support its weight.
06:13Until it's so heavy, the insect muscles can't move it.
06:19Ants can only be this strong because they're so small.
06:25But human technology can overcome some of these limitations.
06:30This exoskeleton can be worn by humans to make them as strong, so to speak, as ants.
06:37To lift easily weights that would be impossible for a normal human.
06:42But it only works because muscle power is amplified by powerful hydraulic motors.
06:49And that means the suit must be connected to cables providing electrical and hydraulic power.
06:55It can't be used on its own.
06:56But understanding the exoskeleton has given Professor Kazarouni and his team at Berkeley ways to design a lightweight and self-contained exoskeleton to give the power of movement to people with paralyzed legs.
07:13Kazarouni explains.
07:14Our goal here is to create this technology of exoskeleton for people with mobility disorder.
07:23And the whole idea is to help you do the daily tasks that you would be doing.
07:30For example, stand up, sit, walk, stop.
07:33There's not much in there.
07:35But if you have all that stuff, then it enables you to do a lot more independent.
07:40Go around the park and around the city, do your job and everything.
07:42Steven Sanchez is working with the team to refine the system.
07:48The way I was injured was breaking my L1 vertebrae on my BMX bike, doing a dirt jump.
07:55And from that left me paralyzed from the waist down.
08:00He's been in a wheelchair ever since.
08:04Because I'm in a wheelchair, people perceive only the wheelchair, not what's here and what's here.
08:12With a new leg system, Steven can stand on his own.
08:23But will he be able to walk unaided?
08:42I like this machine a lot. I'm real happy.
08:44I've had a smile on myself for the past week that I've been in this thing.
08:49It feels great to be walking around.
08:53To make their designs efficient and lightweight, the team studies nature's skeletons.
08:59But not of humans. They studied the way exoskeletons moved.
09:03Michael McKinley is researching how to improve the leg joints in the system.
09:10I took a number of interesting courses that looked at research in natural organisms,
09:17specifically cockroaches and crabs.
09:20And one thing that struck me was how simple these creatures were.
09:23So if you look at the example of a cockroach, the springiness of their legs and the springiness of their exoskeleton
09:31produces a suspension tuning almost, similar to a high-performance race car.
09:36And so by tuning this suspension properly, they're able to maintain stability over very high speed running,
09:44over very difficult terrain.
09:45We're talking terrain with an obstacle that would be shoulder height for us.
09:50And they can go over this at the same speed they'd run on flat ground.
09:54And so one would think that it would take lots of control, lots of brain power to control the limbs to maintain stability.
10:03But in their case, most of that is just done through the mechanics of the structure.
10:10Applying these principles to a human isn't easy.
10:13It takes some trial and error.
10:17It's still a trip doing this.
10:20So gotta watch the ground almost.
10:26Steven's parents have come to see his progress.
10:28It feels great to walk around in an EXO because walking is what you naturally want to do anyways.
10:46Since I've become more comfortable in it now, I'm feeling like it's gonna beat to the point where I'm walking around everywhere in it.
10:58Steven's mother is thrilled to see him walking again.
11:02I'm so excited.
11:04I always told him the technology and the way things are in his age that someday he'll walk because he's so young when it happened that I just knew the technology was out there somewhere and he found it.
11:17It's just awesome.
11:19Can't be happy.
11:20It's very overwhelming just being outside with the walking world walking, not on wheels.
11:30Much different reaction from people.
11:34It's a fun project.
11:35I'm digging it.
11:38It's a great machine that they made and every time I get in it, I'm smiling most of the time.
11:43I can't stop, usually.
11:52Ants and cockroaches bring hope to those who want to walk again.
11:56What else can we find in the library of life?
12:02One of life's most important challenges, to eat.
12:06Some live by hunting other creatures and others try to avoid being eaten.
12:11A crucial weapon for both predator and prey is camouflage.
12:19Camouflage has a simple purpose.
12:22Look inconspicuous to creep up on prey.
12:26Or hide to escape being caught.
12:32There are several ways that camouflage is used in the natural world.
12:35One is to blend into the background and take on its color or pattern.
12:45Another is to look like something completely different.
12:49Something that's not out of place in the environment.
12:52Like a dead leaf.
12:54A dead leaf.
13:11Nature has perfected the art of camouflage.
13:15And camouflage is also used by humans.
13:19Mostly by the military.
13:20The simplest way is to try to blend into the background.
13:25But this only works for a particular environment.
13:29Move somewhere else and this camouflage is useless.
13:33It would be much more powerful if we could change the camouflage to match the background every time we change our surroundings.
13:42The masters of this sort of camouflage live in the ocean.
13:52Octopus, squid and cuttlefish.
13:56With no hard shell to protect them, they rely on disguise to stay out of danger.
14:01They can change the color and pattern of the skin to match the background behind them.
14:12To add to the effect, cuttlefish also raise their tentacles to match the vertical shape.
14:17To add to the effect, cuttlefish also raise their tentacles to match the vertical structure of seaweed.
14:33To add to the effect, cuttlefish also raise their tentacles to match the vertical structure of seaweed.
14:36Sometimes a cuttlefish just sits still and lets its colors pulse.
14:54So, how does it change its colors so fast?
14:59The answer lies inside the skin.
15:07With tiny structures called chromatophores.
15:14There can be hundreds of these to the square millimeter.
15:19Inside each chromatophore, colored pigments are held in tiny elastic bags.
15:24When the cuttlefish wants to display that color,
15:26mussels open the sacs, stretching them into discs, displaying that color.
15:34Red, yellow and black combine to create a range of colors and patterns.
15:39But for a cuttlefish to match its background, it must know what the background looks like.
15:56The eyes of the cuttlefish are on top of its head.
16:00So, how does it know what's behind it?
16:02The same light-sensitive proteins found inside the eye are found in some areas of the skin.
16:10So, it's possible this gives them some sense of the background.
16:14Another way is for the cuttlefish just to look sideways.
16:19Whatever it sees, it assumes to be its background.
16:21Either way, it's as if cuttlefish can see behind them and create the background on their bodies.
16:30Making them almost invisible.
16:35For a soldier, it would be like having a camera on his back, feeding the image onto a screen on his front.
16:41This way, he could disappear into the background unseen.
16:52Or not.
16:54This experiment shows how hard it is.
16:57The system needs a lot of power, and the screen and camera are heavy.
17:02And the angle of the camera is critical to making the image look realistic.
17:06So, if we find it so difficult, how does the cuttlefish make it seem so easy?
17:17Let's give it more of a challenge and introduce the cuttlefish to our environment.
17:27It sees the vertical stripes of the wallpaper as seaweed, but it's not very effective.
17:36On the mottled sofa, the camouflage is more realistic.
17:43The pattern looks like a sandy seabed.
17:53But on the checkered floor, the cuttlefish is really struggling.
17:57Nature doesn't often do straight lines and squares.
18:00The cuttlefish is better at matching the types of pattern it meets in the natural world.
18:08Tests like this show that cuttlefish have only three sorts of responses.
18:13It can make the same pattern all over, like sand.
18:19Or make a more mottled pattern, like gravel.
18:21Or try to match a background of larger pebbles with a white patch.
18:27So, on the checkered floor, it's trying to make its big pebbles pattern.
18:33In its own world, this strategy is near perfect.
18:37And although the camera and screen camouflage is impractical,
18:40the military have designed another way to adapt the cuttlefish method to disguise a very big object.
18:52A tank.
18:57Tanks are big and noisy.
18:59And when the engine is running, the body becomes hot.
19:02The army often carry out maneuvers at night.
19:06And although it's hard to see a tank in the dark,
19:09the army uses another method to see.
19:12They use heat.
19:14Infrared.
19:16Seen with infrared, the tank stands out as white.
19:20It's warm.
19:23But new technology can change all that.
19:26Like the cuttlefish, this tank is covered by special sensors and tiles.
19:31Alex Parfit is Head of Adaptive Camouflage Systems at BAE.
19:38By changing the temperature displayed by the tiles,
19:42we can change the infrared signature.
19:44We can use that to match the background in much the same way as a cuttlefish does.
19:48By using electro-optic sensors mounted on the turret,
19:51we can measure the heat intensity on one side and displayed on the other side of the vehicle,
19:55making it appear completely invisible in the infrared spectrum.
19:58This is a seam recorded to an infrared sensor.
20:01As you can see on the left is a car,
20:03and on the right is one of our tanks fitted with the adaptive technology.
20:07By measuring the infrared signature around it,
20:09we can make the tank completely disappear.
20:16Camouflage at its most effective.
20:18For most predators, accurate vision is a critical sense.
20:36To be able to see prey at a distance and then attack.
20:40When it comes to vision, most birds have much more sophisticated eyes than ours.
20:52Their colour vision is more sensitive.
21:01They can differentiate more colours than us,
21:04and this is a big advantage to some sorts of birds.
21:11The kingfisher.
21:12Kingfishers hunt fish, but this presents a problem.
21:18They have to see through the surface of the water to spot their prey.
21:25The greatest problem is the surface itself.
21:28It reflects light, making it hard to see the fish below.
21:32But kingfisher vision overcomes this problem.
21:50Like many birds that hunt fish or spend time over water,
21:54their eyes contain filters that reduce the amount of blue light they see.
21:58It's not clear exactly how this works,
22:01but it could help them see through the surface reflections to target their prey.
22:14This ability to filter out different colours has been developed for human use.
22:23Engineers have designed a special camera that can be mounted on an aircraft.
22:28This is really multiple cameras, all seeing different colours,
22:33and the operator can choose to add or subtract whichever colours he needs to enhance the image.
22:42To human eyes, peering down on the ocean from an aircraft,
22:46the surface of the sea looks completely opaque.
22:51But by manipulating the different wavelengths that form the image,
22:56it's possible to cut through the surface glare and see down into the ocean itself.
23:05Dustin Medeiros interprets the images.
23:06What you'll see a little bit of is, as we're flying over the water,
23:07you'll see a little bit of splashes on this, but this is mostly video.
23:09Right now we're in the middle of a turn, we're going to come around for another pass.
23:10Right now we're in the middle of a turn, we're going to come around for another pass.
23:16This camera system has a very valuable use in conservation.
23:20And if you're using the image of the picture, you can see a little water,
23:26which is a big, like, you have to pull up the surface.
23:30Right now, we're in the middle of a turn.
23:31We're going to come around for another pass.
23:40This camera system has a very valuable use in conservation.
23:46Many whales are threatened by extinction.
23:48And vital to any management plan is
23:51to know how many there are and where they are.
23:56We used to try to count them from aircraft.
23:59But unless they were very close to the surface,
24:01they couldn't be counted accurately.
24:05But with this system, seeing below the surface
24:08reveals how many whales there are.
24:19Stabilizing and starting capture.
24:23And got them, and holding.
24:26So from here, we can clearly see one.
24:29The second one is very easy to see.
24:31The other one is mostly diving at the moment.
24:34So that's from the visual angle.
24:36So what we can see from the images coming down
24:38is all three whales are clearly standing out
24:40against the background.
24:41So we can confirm now that there is actually three whales there
24:45and that they're traveling.
24:46And actually, I can hold on them and follow them
24:48and track them as they move.
24:51We can see the whales and we can see what they're doing.
24:56The camera may be even more sophisticated than the Kingfisher.
25:00The computer doesn't just filter out the blue from the surface.
25:03It can filter out different blues or greens.
25:06If you use the blue and the green,
25:09one sees down into the depths of the water
25:12and one reflects off the surface of the water.
25:17Manipulating the colors that the camera can see
25:19allows us to see into different depths,
25:22several meters below the surface.
25:24This camera has huge potential, not only for whale surveys,
25:35but to track whales on their migrations.
25:37Whales face almost insurmountable problems,
25:41so every tool we can use will help to make a difference.
25:49The biological arms race has also driven the evolution
25:52of natural materials.
25:55Materials we've been harvesting for millennia.
26:00Ivory, whale baleen, or wool.
26:12But rather than just collecting these materials from nature,
26:16we'd like to be able to make them for ourselves,
26:19particularly the most elusive and most amazing...
26:25silk.
26:29It's one of the most incredible weapons in the arms race
26:32and could be very useful to us if we knew how to make it.
26:37This is spider silk.
26:41Spider silk makes the ultimate trap.
26:43The web is light, strong, and sticky.
26:49It's almost invisible and incredibly strong.
26:52And spiders make different types of silk for different tasks.
26:56The web is light, strong, and sticky.
27:00Once caught, the victim can't escape.
27:01Then the spider spins a different type of silk to wrap up her prey.
27:05We know what the spider silk is made of.
27:07It's a type of protein.
27:08But we can't spin it like they do.
27:09We know what the spider silk is made of.
27:10It's a type of protein.
27:11But we can't spin it like they do.
27:13It's not practical to farm spiders in large numbers.
27:38It's not practical to farm spiders in large numbers to generate enough silk for us to
27:45study.
27:47They just eat each other.
27:50So we turn to other materials in nature that might be easier to use.
27:55And one example is made by a bizarre creature found in the depths of the ocean.
28:03The hagfish.
28:06Although they sometimes hunt for prey, they're often found scavenging on a carcass on the
28:11seabed.
28:12They're usually the first to arrive and, if they can, they'll try to eat the carcass from
28:17the inside out.
28:28Hagfish are not, at first sight, very attractive creatures.
28:34They have one enthusiastic fan in scientist Eddie Kisvaloudi.
28:46First, he must collect them using ripe dead fish as bait.
28:52He lowers his trap to the bottom, filled with stinking rotten mackerel to tempt the hagfish.
29:03The trap hits the bottom 70 meters down and the hagfish arrive immediately.
29:09They're more interested in the dead fish than the danger of the trap.
29:20they come with something that wasn't there before.
29:39Slime.
29:41Lots of it.
29:42And it's the slime that Eddie's interested in.
29:55So, where's the slime coming from?
30:04If we can lift it up just a little bit, you can see these little white pores on the side
30:09of the animal.
30:10They're just, they're right along there.
30:12And there's a protein that comes out of that.
30:14When it hits the seawater, it expands to huge volumes and it can turn a small tank like this
30:19into slime in just a few seconds.
30:25So why do hagfish make so much slime?
30:28Simple.
30:29For defense.
30:33The hagfish just slimes its attacker.
30:36The slime expands into the predator's mouth, clogging gills and leaving it gagging.
30:42And the hagfish just goes back to feeding.
30:47No other fish in the ocean has this ability to basically slime its predators and escape,
30:53leaving the shark or fish completely repulsed.
30:58One hagfish produces a lot of slime.
31:01But for Eddie to study its properties, he needs to generate a lot more of it.
31:06On the southern coast of California, the Scripps Institute of Oceanography is the ideal
31:12place for Eddie to demonstrate why he's so excited about slime.
31:22When the tank is full of seawater, the hagfish are poured in.
31:26Below me is a tank filled with about 50 hagfish and it's about 1600 liters of seawater and all
31:55we have to do is just agitate them just a little bit to see what they'll do.
31:59And that's my job.
32:09And the result is slime.
32:12Plenty of slime.
32:16Let me try this so you can just see it there.
32:19And that was just from a little tap from my foot and it just created a huge amount of slime.
32:41That is absolutely disgusting.
32:44I think I got some on my face actually.
32:50Now you can see it dripping off here.
32:52This is the protein.
32:53It's wrapped onto all the seawater.
32:56And what we want to do is really just get rid of all the seawater so only the protein is left.
33:02The best way to do that is to hang it on these drying racks over here.
33:06We're just going to drape it over the side here.
33:07And what we want to do is just dry it overnight to be sure that all the seawater actually evaporates.
33:13And so we're just going to leave it just like that and see what happens tomorrow.
33:17Dried hagfish slime.
33:33It's what happens when you hang it for a few hours.
33:35All the seawater just dries right off of it and you're left with this very fine filamentous protein type structure.
33:43And what we want to do is just see how strong this stuff really is.
33:47Now we've got this weight, it's about 12 ounces.
33:51We're going to slide that on and see if it's strong enough to hold.
33:56It holds that fine.
33:59We've got this big weight right down here.
34:05This is a 15 pound dumbbell that you normally use for working out.
34:11This is what we use for anchoring the hagfish traps offshore.
34:15I'm just going to hold it like that.
34:20Okay.
34:2215 pounds.
34:24Slime.
34:28And it's really difficult to hold on to.
34:31That is amazing.
34:34It's holding this 15 pound dumbbell weight.
34:38I can barely hang on to this right here on the edge.
34:41That is strong stuff.
34:43Wow.
34:45Well, we know the limits of what hagfish slime can hold.
34:51But just those little filaments, it was just slime a few hours ago.
34:56And it held 15 pounds worth of weight.
34:58Now, this is interesting to us because this might be a new synthetic material.
35:02Maybe a nylon.
35:03Could be something that we can make clothing out of.
35:06But this stuff is just remarkably strong.
35:10Quite amazing.
35:11Hackfish slime has great potential.
35:16But hackfish live in the deep ocean and to get the slime involves stressing them out.
35:21So, can we make a similar material on an industrial scale that has all the advantages of slime,
35:28but is made of materials that are readily available.
35:38Javier Fernandez at the Wyss Institute in Harvard is well on the way to achieving that goal with a material he calls shrilk.
35:52Shrillk can be made from materials that are common in the natural world.
35:56Javier was inspired by specimens in the Harvard Natural History Museums.
36:06He realized the natural world is full of materials made from the same basic ingredients.
36:12And he worked out how to combine those ingredients to make his new material.
36:18So, the main advantage of this material is that it is made of natural sources.
36:23So, we have an almost unlimited raw material.
36:29Chitin is the hard stuff from the shells of creatures like shrimps.
36:33It's treated to create a liquid and poured into a dish, spread out and left to dry.
36:41The other ingredient is raw silk from silkworms, made of a type of protein called fibroin.
36:51Javier isolates this fibroin by dissolving the silk in a solvent.
36:57To filter out the fibroin from the mixture, he pours it into a cellulose bag and stands it in a jar of water.
37:06The jar is stirred mechanically for 48 hours or so.
37:27At the end of the process, Javier opens the bag, which now contains concentrated fibroin.
37:37He pours it onto the dish containing the dried chitin, forming a laminate of silk and shrimp.
37:46This is also left to dry.
37:48And when Javier returns, he has a strong sheet of transparent material.
37:53He's made shrilk.
37:56It looks like plastic, but has a big advantage.
38:02Shrilk is both strong and completely biodegradable.
38:09And the good thing also is that the material can be recycled.
38:14And also because the main component has a lot of nitrogen, will work as a fertilizer.
38:20Shrilk is adaptable.
38:22It can be shaped and molded into all sorts of packaging applications
38:27and uses materials that are cheap and easily available in a simple process.
38:33Today, egg boxes, tomorrow, the world.
38:44In the arms race, some predators rely on stealth to get close to their prey.
38:51And for a predator that hunts from the air, a big advantage is silent flight.
39:02To approach prey giving no warning.
39:08Can we learn from the use of stealth as a weapon?
39:15The expert in silent flight is the owl.
39:24So, what does this have to do with a tropical paradise?
39:30Get away from it all to the peace and quiet sun, sea, sand.
39:40But this particular beach has a unique tourist attraction.
39:43Oh my God.
40:07Here in St. Martin's in the Caribbean, the island is so small, the runway is very close
40:17to the beach. So close that the turbulent downdraft and noise have become something
40:23of a spectacle. Tourists here see the low flying planes as part of the local character.
40:37But everywhere else in the world, noise and turbulence are real problems. Engineers
40:50are trying to find a way to reduce these. And to do that, they've turned back to nature.
41:03Owls hunt at night and rely on sound, or lack of it. Their prey, mice and voles, have extremely
41:10sensitive hearing. The owl must swoop down on its prey so quietly it won't hear it coming
41:16and escape. But one careless rustle of a branch sends the prey scurrying for cover.
41:33The owl's weapon is silence, and its prey's defense is acute hearing.
41:53Owls are the quietest birds in flight. But what makes them different from other birds?
42:05We can see the difference in the way the owl and the pigeon fly. The pigeon is about the
42:10same size as the same size as the owl, so is a good comparison. Noise is created by wings
42:16moving through the air, breaking up the air behind the wing. Flying both birds over a bed
42:22of feathers show how different this effect is. The pigeon wings create turbulence that disturbs
42:29the feathers as it passes over them. But the owl hardly moves the feathers at all.
42:52Somehow the owl is reducing the turbulence coming off the wings, and hence the sound the wing
42:57beat makes.
43:05This is a barn owl. So quiet, it's also known as the ghost owl.
43:11A barn owl finds its prey by listening for the slightest sound. Its face is shaped like a dish to capture
43:30sound and direct it to its ears. So the owl can't afford to make any noise at all as it
43:41approaches its prey. Can a barn owl really be this silent?
43:48Bird handler Lloyd Bug works with his trained barn owl, Kensa. She's been trained to fly onto
43:56a beeper buried in the grass.
44:03Lloyd is going to find out for himself how quiet Kensa really is.
44:08He and his wife Rose are setting up a test. Can Lloyd hear the owl's approach?
44:23Right, ready? Yeah, you're going to put it there? Yeah, yeah. I'm going to put it right there.
44:35Lloyd will keep his eyes closed and listen for Kensa's approach.
44:39Okay. Now if I think she's there, I'll raise my hand.
44:44Okay, my eyes are closed.
44:48Rose activates the target beeper to guide the owl.
44:51I could not tell she was there at all. Sure? Yeah, I had no idea. I thought you were going to put your hand up.
45:04You cannot tell she's there. Not until her little feet touch down in the grass.
45:18Nothing at all? No, nothing.
45:20You clever girl.
45:25Lloyd's hearing is good for a human, but we can measure the sound more accurately.
45:31We can take a barn owl into a specialist sound facility in Germany.
45:37It's designed to absorb all sound. It's soundproof, so no sound can enter from the outside world.
45:45And the walls are structured so that echoes don't reflect back into the room.
45:51Any sound in the chamber is deadened. Totally.
45:58So sound can be measured very accurately.
46:03Bird handler, Micah Schmidt, has brought a barn owl into the chamber to measure any sound its wings make as it flies.
46:10But there's a problem.
46:15A barn owl depends so much on hearing to orientate itself.
46:19In this silent chamber, it won't fly free.
46:23So Micah rocks him on her wrist, so he has to flap his wings to keep his balance.
46:31The result is silence.
46:35So how do owl wings make so little noise?
46:42If we understood that, could we apply that to our own technology?
46:50One reason is that the curved shape of the owl wings means they can fly very slowly and flap less often than birds of a similar size.
46:59But the texture of the wing itself is crucial to the way the wing works.
47:06In Aachen, Germany, engineers are studying how different textures affect a wing's performance in a wind tunnel.
47:17First, they tried a basic wing with a smooth surface.
47:20Their results showed that the air passing over this wing separates off from the surface, which is not very efficient.
47:36But the owl wing has a soft, velvety texture.
47:46So they tried covering the wing with velvet.
47:49This time, they saw that the air passed smoothly over the wing.
47:54It made the wing more efficient, and on the owl wing, the velvety texture reduced the sound of the feathers sliding over each other.
48:09So, can this discovery be used by the airline industry?
48:14Should we glue patches of deep-piled carpet to aeroplane wings?
48:17The aerodynamics of large wings are very different from small wings such as birds' wings.
48:25This would make it worse instead of better.
48:28But there's another property of the owl's wing that also reduces noise.
48:34Biologist Thomas Bachmann studies how real owl wings perform in the wind tunnel.
48:39The wind speed in the canal is 5 meters per second.
48:44What is the normal flight speed of schleier-eulens.
48:48One of the specials of the oil-eulens are these small franses on the back end.
48:53And here it is thought that these franses influence the aerodynamics of the plane.
49:01The fringes reduce the turbulence behind the wing, which contributes to the noise the wings make in flight.
49:07And we can apply this design to our own technology.
49:17Fans occur everywhere, from the inside of computers to huge air conditioning units.
49:24If they could be made more efficient, there would be huge savings in energy and noise.
49:37The engineers in Germany are testing a fan that is based on the owl wing design.
49:46A fan this size should be uncomfortably loud.
49:49But the Owlet fan is surprisingly quiet.
49:53It's being tested in the sound chamber.
49:55The great breakthrough was that it was used to use.
50:00By the
50:09The engineers based the geometry of the blade on the owl wing, giving the edges serrations like the fringes on the feathers.
50:39This is the snap of the tail end. Here we can find the contour of the tail end of Eulenflugels.
50:46This special tail end contour is a extreme reduction of the noise level for the ventilators.
50:54These owl-like serrations reduce turbulence and noise.
50:59We can't use the techniques of an owl wing on a wing the size of a plane, but owl technology could help planes cut noise in another way, applying serrated edges to the casing of the engine.
51:17Dr. James Bridges of NASA's Glenn Research Center explains.
51:22These are being used in the aircraft that are being turned off the production line today are the ones that will soon be coming off the production lines.
51:29They've been in the initial flight tests. The chevrons are the sawtooth pattern, and that is a change from just the regular smooth round lip that most nozzles have.
51:40That change modifies how the flow downstream of the engine makes noise, makes it so that it doesn't make as much noise, which is obviously what we all want, the aircraft to be quieter.
51:51These work in a similar way to the fringes on the trailing edge of owl wings, reducing turbulence and noise whilst increasing efficiency.
52:01But that might wreck the tourist industry in St. Martins.
52:22In three and a half billion years of evolution, nature has solved a host of problems.
52:28But there's a lot more hidden, just waiting to be discovered in the vast library of life.
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53:12You