Original subtitles

♪♪

Garrod: SKIN --

WE ALL HAVE IT,

AND SO DOES EVERY VERTEBRATE ON THE PLANET.

IT KEEPS THE OUTSIDE OUT

AND THE INSIDE IN.

ANIMALS MAY LOOK VERY DIFFERENT ON THE SURFACE,

BUT WE ALL SHARE THE SAME BASIC SKIN BLUEPRINT.

I'M BEN GARROD, PROFESSOR OF EVOLUTIONARY BIOLOGY,

AND I'M FASCINATED BY THIS OFTEN OVERLOOKED WONDER OF NATURE.

IT'S NOT JUST A CASE THAT HE'S HAIRLESS.

THE SKIN'S TOTALLY DIFFERENT.

Garrod: NOW GROUND-BREAKING NEW SCIENCE...

THIS IS REALLY QUITE REMARKABLE.

IT SHOULD BE A GAME CHANGER FOR SO MANY PEOPLE.

THAT SOUND -- OH, IT MAKES THE HAIR

ON THE BACK OF YOUR NECK GO UP, DOESN'T IT?

Garrod: ...IS REVEALING SKIN'S MYSTERIES.

IT REALLY TRANSFORMS OUR UNDERSTANDING OF DINOSAURS.

I'M GOING TO EXPLORE THE NATURAL HISTORY

OF THE BODY'S LARGEST ORGAN

TO SEE HOW SKIN HAS ALLOWED ANIMALS

TO CONQUER EVERY HABITAT,

DISAPPEAR INTO THEIR SURROUNDINGS,

AND DEVELOP EXTRA SENSORY ABILITIES.

WE'RE EVEN DISCOVERING THE COMPLEX ECOSYSTEM

LIVING ON OUR SKIN.

OH, JIM, THAT'S AWFUL.

[ Laughing ] IT REALLY IS.

Garrod: IN THIS EPISODE, I'LL FIND OUT WHY SHARK SKIN

IS COVERED IN THOUSANDS OF TINY TEETH...

NOW, I LOVE SHARKS, BUT I'M NOT ABOUT TO GIVE THIS ONE A STROKE.

...HOW BIRDS HAVE ADAPTED THEIR SKIN TO RULE THE SKY...

-OOH! -OH.

-AND DOWN HE GOES. -ROBOCROW IS DOWN.

...AND HOW A GECKO'S SKIN ALLOWS IT

TO DEFY THE LAWS OF GRAVITY...

HE'S ABLE TO CLING ONTO THIS PIECE

OF VERTICAL, SMOOTH GLASS WITH EASE.

...AS I EXPLORE HOW ANIMALS USE THEIR SKIN

TO MOVE THROUGH THE WORLD AROUND THEM.

I'M GOING TO REVEAL THE SECRETS OF SKIN.

--Captions by VITAC-- www.vitac.com

CAPTIONS PAID FOR BY DISCOVERY COMMUNICATIONS

MOVEMENT IS CRITICAL FOR THE SURVIVAL OF ANIMALS.

FISH SWIM.

MOLES DIG.

SUGAR GLIDERS LEAP.

AND HUMMINGBIRDS HOVER.

MUSCLES AND BONES MIGHT DO A LOT OF THE HEAVY LIFTING,

BUT IT'S ADAPTATIONS TO THEIR SKIN

WHICH HAVE ALLOWED THESE ANIMALS TO MOVE

IN THE WAYS THAT THEY DO.

AS WE'LL DISCOVER,

SKIN IS ESSENTIAL FOR ALL TYPES OF MOVEMENT.

♪♪

FISH ARE SHAPED THE WAY THEY ARE

BECAUSE THEY NEED TO BE STREAMLINED ENOUGH

TO MOVE THROUGH THE WATER

WHILE USING THE LEAST AMOUNT OF ENERGY.

BUT ONE GROUP OF FISH HAVE TAKEN STREAMLINING TO THE NEXT LEVEL,

WITH A SUPER HYDRODYNAMIC SURFACE TO THEIR SKIN.

SHARKS -- SOME OF THE MOST FORMIDABLE HUNTERS

IN THE OCEANS.

THE MAKO SHARK HUNTS SOME OF THE FASTEST FISH IN THE SEA,

SUCH AS TUNA AND SWORDFISH...

...SO HAS EVOLVED TO BE INCREDIBLY QUICK,

REACHING TOP SPEEDS OF OVER 64 KILOMETERS PER HOUR.

AND AS WITH ALL SHARKS, THEIR SKIN PLAYS A CRUCIAL ROLE

IN HELPING THEM DO THIS.

-OKAY. -WE GOOD?

I'M AT BLUE PLANET AQUARIUM IN CHESTER,

WHERE I'M ABOUT TO GET VERY CLOSE TO THESE PREDATORS.

IN THIS TANK IN FRONT OF ME,

THERE ARE FIVE DIFFERENT SPECIES OF SHARK,

ALL OF WHICH ARE INFINITELY MORE SUITED

TO MOVING THROUGH THE WATER THAN I AM.

ANYONE WHO'S BEEN IN A POOL WILL KNOW

THAT MOVING THROUGH WATER

IS A LOT HARDER THAN MOVING THROUGH AIR.

WHEN I MOVE THROUGH THE WATER LIKE THIS,

MY BODY IS CREATING A HUGE AMOUNT OF RESISTANCE.

AND THIS REALLY SLOWS ME DOWN.

AND IT'S BECAUSE OF THIS RESISTANCE

THAT I CAN'T MOVE THROUGH THE WATER VERY FAST.

BUT SHARK SKIN IS PERFECTLY ADAPTED

TO REDUCE THE RESISTANCE CREATED AS THEY SWIM,

AND SO THEY CAN SLIP THROUGH THE WATER WITH RELATIVE EASE.

NOW, I LOVE SHARKS, BUT I'M NOT ABOUT TO GIVE THIS ONE A STROKE.

BUT IF I DID, I WOULD FEEL THAT FROM THE HEAD

TO THE TAIL IS VERY SMOOTH.

BUT FROM THE TAIL TO THE HEAD IS ACTUALLY VERY ROUGH.

AND THAT'S BECAUSE IF YOU LOOK AT THE SKIN OF A SHARK

IN MICROSCOPIC DETAIL,

YOU'LL SEE THEIR SKIN ARE EFFECTIVELY COVERED

IN MILLIONS AND MILLIONS OF TINY TEETH.

THESE DERMAL DENTICLES GROW OUT THROUGH THE TOP LAYER OF SKIN,

THE EPIDERMIS.

THEY ARE MADE FROM A HARD MINERAL CALLED VITRODENTINE

ON THE OUTSIDE

AND SOFTER DENTINE ON THE INSIDE.

IT'S INCREDIBLY SIMILAR TO THE MATERIAL

HUMAN TEETH ARE MADE FROM.

DENTICLES FORM A REGULAR PATTERN

ALL OVER THE SKIN OF EVERY SHARK IN THE OCEANS,

WITH EACH SPECIES HAVING DIFFERENT-SHAPE DENTICLES

UNIQUE TO THEM.

♪♪

THESE DERMAL DENTICLES HAVE EVOLVED TO ALLOW THE SHARKS

TO SLIP SEAMLESSLY THROUGH THE WATER.

IT MAKES THEM MORE STREAMLINED, AND IT REDUCES RESISTANCE.

AND THIS ALLOWS SHARKS TO SWIM NOT ONLY FAST AND STEALTHILY,

BUT BY SAVING SO MUCH ENERGY,

THEY CAN COVER HUGE DISTANCES ACROSS OCEANS.

ALL OF THESE THINGS HAVE HELPED TURN SHARKS

INTO VERY EFFICIENT HUNTERS.

THESE INCREDIBLE IMAGES ARE CT SCANS OF BABY SHARKS,

PRODUCED AT THE NATURAL HISTORY MUSEUM

IN LONDON.

THE SHARKS IN THESE IMAGES ARE ONLY A FEW WEEKS OLD,

BUT YOU CAN ALREADY CLEARLY SEE THE REGULAR ARRANGEMENTS

THAT DENTICLES FORM IN THE SKIN.

DR. TOM FLETCHER FROM LEICESTER UNIVERSITY

IS AN EXPERT ON SHARK HYDRODYNAMICS.

I'VE SEEN SOME AMAZING SHARKS RECENTLY,

AND ONE THING THAT REALLY THROWS ME

IS OBVIOUSLY THEY'RE COVERED IN DENTICLES,

BUT I DON'T FULLY GET HOW THOSE DENTICLES HELP THEM

MOVE THROUGH THE WATER WITH SUCH EASE.

SCIENTISTS FOR YEARS WERE PERPLEXED

BY THE ROUGHNESS OF THESE SHARKS

AND HOW THEY WERE MANAGING TO REDUCE DRAG SO EFFECTIVELY.

NOT ONLY ARE THE DENTICLES QUITE ROUGH,

BECAUSE THERE ARE LOTS OF THEM

ALL JUTTING UP NEXT TO EACH OTHER,

LIKE WE HAVE HERE,

BUT THEY'RE ALSO VERY ROUGH ON THE SURFACE AS WELL.

OBVIOUSLY, THESE AREN'T ACTUAL DENTICLES.

YOU'VE HAD THESE 3D PRINTED,

AND THEY'RE MUCH LARGER THAN REAL LIFE, YEAH?

YES, THEY'RE ABOUT 1,000 TIMES BIGGER THAN THEY SHOULD BE.

IF YOU LOOK AT SHARK DENTICLES IN REAL LIFE,

THEY'RE LIKE GRAINS OF SAND. THEY'RE ABSOLUTELY TINY.

AND WHAT WE HAVE HERE IS, WE HAVE A SECTION OF SHARK SKIN.

THESE ARE DIFFERENT SPECIES.

THIS IS A LEOPARD SHARK, AND WE HAVE A SINGLE ONE HERE.

THIS IS PROBABLY THE FASTEST SHARK THAT WE'VE GOT

IN OUR OCEANS TODAY.

IT'S THE MAKO SHARK.

THESE SHOW REALLY NICELY THE MICROSCOPIC STRUCTURES

THAT ARE REDUCING DRAG.

THE KEY ARE THESE RIBLETS HERE, THESE PEAKS AND TROUGHS

THAT WE HAVE ON THE SURFACE.

AND THE WAY THEY WORK IS BY REDUCING THE FRICTION

OF THE SWIRLING FLUID ABOVE THE SURFACE.

SO IF, FOR EXAMPLE, I'M THE SHARK HERE,

AND THE FLUID'S MOVING OVER THE SURFACE

AND IT'S COMPLETELY SMOOTH,

THAT'S A VERY LARGE AREA FOR FRICTION TO OCCUR.

IT'S SORT OF LIKE GOING ONTO AN ICE RINK WITH BIG SNOWSHOES ON.

IF YOU'VE GOT BIG, FLAT SNOWSHOES

THAT ARE NICE AND SMOOTH,

ACTUALLY, YOU'VE GOT LOTS OF FRICTION THERE,

WHEREAS AN ICE SKATER WITH THAT THIN BLADE OF METAL

INTERACTING WITH THE ICE, JUST LIKE THESE RIBLETS,

THE FRICTION IS MUCH REDUCED AND YOU CAN GO MUCH FASTER.

Garrod: IN FACT, SHARK DENTICLES ARE SO GOOD AT THEIR JOB,

THEY'RE INSPIRING A WHOLE HOST OF NEW TECHNOLOGIES.

PEOPLE HAVE BEEN VERY INTERESTED IN REDUCING DRAG BY 10%,

THAT'S REALLY, REALLY ENORMOUS, AND IT CAN SAVE A LOT OF ENERGY.

IN AIRCRAFT, FOR EXAMPLE, THEY'VE TINKERED WITH THIS,

THE UNDERSIDE OF BOATS AS WELL.

IF YOU NEED TO MOVE A FLUID ACROSS A SOLID SURFACE,

THEN THIS COULD POTENTIALLY REALLY HELP.

GOOD OLD SHARKS.

Garrod: IF YOU LOOK CLOSE ENOUGH,

YOU'LL FIND A HIDDEN MICROSCOPIC WORLD

ON THE SURFACE OF THE SKIN OF MANY ANIMALS,

HELPING THEM MOVE IN WAYS WHICH OFTEN APPEAR IMPOSSIBLE.

LIKE SHARKS,

GECKOS USE THEIR SKIN TO HELP THEM HUNT PREY.

HOWEVER, WHEN YOUR FOOD IS AN INSECT

WHICH COULD LAND VIRTUALLY ANYWHERE,

IT'S NOT JUST SPEED THAT YOU NEED,

BUT ALSO THE ABILITY TO CLIMB.

AS GECKOS GO, THIS TOKAY GECKO IS PRETTY HEAVY.

BUT STILL, HE'S ABLE TO CLING ONTO THIS PIECE

OF VERTICAL, SMOOTH GLASS WITH EASE.

AND AS HE SPINS AROUND,

WE'RE ABLE TO SEE JUST HOW HE MANAGES TO DO THIS.

YOU MIGHT THINK THE SURFACE OF GLASS IS TOTALLY SMOOTH,

BUT LIKE ALL MATERIALS,

IT'S COVERED IN MICROSCOPIC IMPERFECTIONS.

AND THE SKIN ON A GECKO'S TOES

IS ABLE TO MAKE USE OF THESE IMPERFECTIONS

AND STICK TO THE GLASS.

THIS IS DOWN TO A PHYSICAL PROPERTY

CALLED VAN DER WAALS FORCE.

NAMED AFTER THE 18th CENTURY DUTCH PHYSICIST,

IT'S A WEAK ELECTRICAL ATTRACTION

THAT EXISTS BETWEEN ALL MOLECULES

IF THEY GET CLOSE ENOUGH TO EACH OTHER.

IF I WERE TO PLACE MY HAND ON THE GLASS,

THERE ARE SO MANY RIDGES,

LUMPS, AND BUMPS, THINGS LIKE FINGERPRINTS,

THAT THERE ISN'T ENOUGH SURFACE AREA FOR ME

TO BE ABLE TO USE VAN DER WAALS FORCE

TO STICK TO THE GLASS.

HOWEVER, GECKO TOES HAVE A REMARKABLE MICRO STRUCTURE.

OUT OF THE EPIDERMIS

PROTRUDE HUNDREDS OF THOUSANDS OF TINY FILAMENTS

MADE OF A PROTEIN CALLED KERATIN,

THE SAME STUFF THAT MAKES OUR HAIR AND NAILS.

THESE KERATIN FILAMENTS ARE SO SMALL

THAT FAR MORE OF THE MOLECULES ON THE GECKO'S TOE

COME INTO CONTACT WITH THE MOLECULES ON THE GLASS.

THIS ALLOWS THE GECKO TO USE VAN DER WAALS FORCE

AND ENABLES IT TO CLING ONTO AND MOVE

UP VERTICAL SURFACES.

♪♪

FOR ANY ANIMAL TO MOVE, THEIR SKIN NEEDS TO BE FLEXIBLE.

AND ONE SUBTERRANEAN RODENT

HAS TAKEN THIS FLEXIBILITY TO AN EXTREME.

THE MOST INTRIGUING ANIMAL WITH THE STRANGEST SKIN I KNOW,

LIVES IN AFRICA, UNDERGROUND, AND IS RARELY SEEN.

NAKED MOLE RATS --

THEY'RE ALMOST BLIND AND VIRTUALLY HAIRLESS.

AND UNTIL RELATIVELY RECENTLY,

THESE STRANGE ANIMALS WERE A TOTAL ENIGMA TO SCIENCE.

HI, CHRIS. -HI, BEN. HOW ARE YOU DOING?

-LOOK AT THESE LITTLE GUYS. -YEAH.

DR. CHRIS FAULKES HAS ONE OF THE LARGEST CAPTIVE COLONIES

OF NAKED MOLE RATS IN THE WORLD.

IT'S NOT JUST A CASE THAT THIS LITTLE RODENT IS HAIRLESS.

THE SKIN'S TOTALLY DIFFERENT. IT'S REALLY BAGGY.

WHY ARE THEY SO LOOSE?

HOW DOES IT HELP THEM MOVE, FOR EXAMPLE?

WELL, WE THINK THAT IT HELPS THEM TO PASS EACH OTHER

IN VERY TIGHT SITUATIONS.

SOMETIMES YOU GET A TRAFFIC JAM

WITH SEVERAL ALL TRYING TO GET PAST EACH OTHER

AND THAT LOOSE SKIN HELPS THERE.

Garrod: ONE THEORY IS THAT

ALMOST LIKE BEING IN A SLEEPING BAG,

THE NAKED MOLE RATS' LOOSE SKIN

HELPS THEM WRIGGLE 'ROUND MUCH MORE EASILY IN TUNNELS,

WHERE THERE'S VERY LITTLE ROOM FOR MANEUVER.

IT ALSO HELPS TO HAVE LOOSE SKIN

WHEN YOU'RE LIVING WITH THIS MANY FAMILY MEMBERS.

IN THE WILD, THEY CAN LIVE IN SOCIAL GROUPS

OF UP TO 300 SOMETIMES.

YET, THERE'S ONLY ONE FEMALE THAT BREEDS, THE QUEEN,

AND THE REST ACT AS EITHER DEFENDERS OR HELPERS.

SO IT'S A BIT LIKE THE MAMMAL EQUIVALENT OF A SOCIAL INSECT.

CRAWLING THROUGH THESE SMALL SPACES MEANS CONSTANTLY BUMPING

OR SCRATCHING YOURSELF ON SHARP ROCKS IN THE EARTH.

BUT NAKED MOLE RATS FEEL LESS PAIN THAN OTHER RODENTS.

EVOLUTIONARY CHANGES TO THE PAIN RECEPTORS IN THEIR SKIN

MEANS THAT FEWER PAIN SIGNALS ARE SENT TO THEIR BRAIN,

MAKING THEM PERFECTLY SUITED TO THEIR UNDERGROUND LIFE.

REMARKABLY, THEY LIVE INCREDIBLY LONG FOR A SMALL RODENT,

OVER 30 YEARS.

34 YEARS IS THE RECORD AT THE MOMENT.

SO IF YOU THINK OF A SIMILARLY SIZED MOUSE,

THAT LIVES FOR ABOUT THREE YEARS,

SO MORE THAN 10 TIMES LONGER THAN A MOUSE.

THEY RESIST ALL OF THE NORMAL SIGNS OF AGING.

AND THAT'S NOT EVEN THE MOST REMARKABLE THING

ABOUT THEIR PHYSIOLOGY.

THEY ALSO RESIST GETTING CANCER.

SO PROBABLY LESS THAN 0.3% INCIDENTS OF CANCER

COMPARED TO, IN SOME MOUSE STRAINS,

UP TO 90% DEVELOP CANCER.

SCIENTISTS BELIEVE THIS INCREDIBLE ABILITY

TO RESIST CANCER

COULD BE TO DO WITH A COMPOUND FOUND IN THEIR SKIN.

THERE'S A COMPONENT IN THE SKIN CALLED HYALURONAN,

OR HYALURONIC ACID, WHICH ALL MAMMALS HAVE.

WE HAVE IT.

IT'S OFTEN PRESENT IN SKIN CREAMS AND BEAUTY PRODUCTS.

NOW, NAKED MOLE RATS HAVE A UNIQUE KIND OF HYALURONAN

IN TERMS OF SIZE AND ITS MOLECULAR STRUCTURE.

HYALURONIC ACID IS A COMPONENT OF THE CONNECTIVE TISSUES

WHICH FORM THE STRUCTURE OF SKIN AND OTHER ORGANS.

AND NAKED MOLE RATS HAVE A UNIQUE FORM OF HYALURONIC ACID

WITH A COILED MOLECULAR SHAPE.

THIS MAKES THE MOLECULE ACT ALMOST LIKE A SPRING.

THIS GIVES THE NAKED MOLE RATS THEIR STRETCHY SKIN

AND MIGHT BE A KEY FACTOR IN THEIR ABILITY TO RESIST CANCER.

BUT RESEARCH INTO THIS IS STILL AT AN EARLY STAGE.

WHETHER YOU THINK THEY'RE UGLY OR CUTE,

WHAT'S NOT UP FOR DEBATE

IS THAT THESE SAGGY-SKINNED MEMBERS OF THE RODENT FAMILY

ARE HELPING US UNDERSTAND

AND TACKLE SOME OF OUR MOST DEVASTATING DISEASES.

LIFE IN CHALLENGING ENVIRONMENTS IS OFTEN ONLY POSSIBLE

BECAUSE OF SKIN'S INCREDIBLE VERSATILITY.

♪♪

ONE LEADING THEORY SUGGESTS THAT A SUBTERRANEAN EXISTENCE

DROVE ONE PARTICULAR GROUP OF ANIMALS

TO EVEN MORE EXTREME ADAPTATIONS.

GO BACK 150 MILLION YEARS,

AND THE ANCESTORS OF SNAKES LIVED UNDERGROUND

BUT HAD FOUR LEGS.

BUT THESE LIMBS WOULD HAVE JUST GOT IN THE WAY,

SO OVER TIME, THE SNAKES LOST THEM

AND EVOLVED TO PROPEL THEMSELVES ALONG ON THEIR BELLIES.

BUT NOW, WITH THE MAJORITY OF SNAKES LIVING ABOVE GROUND,

THERE'S ONE QUESTION THAT HAS PUZZLED SCIENTISTS.

HOW ARE SNAKES ABLE TO GET ACROSS FLAT SURFACES

WITHOUT LIMBS?

THE SECRET TO HOW THIS SNAKE IS ABLE TO MOVE

LIES IN THE SPECIALLY ADAPTED SCALES

ON THE UNDERSIDE OF HER BELLY THERE.

[ CHUCKLES ]

AND WHILE THEY MAY LOOK VERY SMOOTH, THEY'RE ACTUALLY

ABLE TO GENERATE A LARGE AMOUNT OF FRICTION.

EACH BELLY SCALE IS MADE OF KERATIN

AND POPULATED WITH MICROSCOPIC PROTRUSIONS.

THE SNAKE CAN GRIP THE GROUND WITH ITS BELLY SCALES

BY USING THESE PROTRUSIONS TO CATCH ON ANY IMPERFECTIONS

ON THE SURFACE.

IT IS THEN ABLE TO PULL OTHER PARTS OF ITS BODY FORWARD.

THE ARRANGEMENT OF THESE TINY PROTRUSIONS IS KEY.

THEY'RE POSITIONED SO THAT WHEN THE BELLY SCALES SLIDE FORWARD

OVER THE GROUND, THEY DO SO SMOOTHLY.

IN ONE DIRECTION, THE SCALE SLIPS.

IN THE OTHER DIRECTION, IT GRIPS,

ALLOWING SNAKES TO MOVE EFFORTLESSLY

THROUGH A RANGE OF HABITATS,

TACKLING VIRTUALLY ANY SURFACE THEY COME ACROSS.

♪♪

THROUGHOUT EVOLUTION,

SKIN HAS USED KERATIN IN A VARIETY OF INGENIOUS WAYS.

IT'S THE MAIN COMPONENT OF NAILS, SCALES, AND HAIR.

BUT NONE OF THESE ARE AS COMPLEX

AS ITS REAL CROWNING ACHIEVEMENT.

FEATHERS --

THEY GROW IN A SIMILAR WAY TO OUR HAIR.

A SHAFT MADE OF KERATIN GROWS OUT OF FOLLICLES IN THE SKIN,

BUT THAT'S WHERE THE SIMILARITY ENDS.

AS THE SHAFT EMERGES FROM THE FOLLICLE,

BRANCHED KERATIN FILAMENTS OPEN OUT,

FORMING A FLAT SURFACE KNOWN AS THE VEIN.

THERE ARE DIFFERENT TYPES OF FEATHERS,

WHICH COME IN ALL SHAPES AND SIZES.

AND IT'S THE FLIGHT FEATHERS

THAT BIRDS GROW FROM THE SKIN ON THEIR WINGS

WHICH ENABLE THEM TO TAKE OFF AND STAY IN THE AIR.

I'VE COME TO THE INTERNATIONAL CENTRE FOR BIRDS OF PREY

IN GLOUCESTERSHIRE TO SEE SOME REALLY IMPRESSIVE FLYERS.

THIS IS A STELLER'S SEA EAGLE.

HE'S GOT A TWO-METER WINGSPAN,

AND HE'S ONE OF THE HEAVIEST EAGLES ON THE PLANET.

AND HE CAN DIVE FROM A PERCH TO CATCH HIS PREY,

OR HE CAN SOAR USING THOSE MASSIVE WINGS

TO LOOK FOR HIS NEXT MEAL.

HE'S GOT HUGE FLIGHT FEATHERS, AND EACH ONE IS LIGHTWEIGHT,

STIFF, BUT IMPORTANTLY, REALLY, REALLY STRONG.

Garrod: IN FLIGHT, THE SHAPE OF A BIRD'S WING

MEANS THE AIR PRESSURE UNDER THE WING

IS GREATER THAN THAT ABOVE.

AND IT'S THIS DIFFERENCE IN PRESSURE

WHICH KEEPS THEM IN THE AIR.

BUT THIS IS ONLY POSSIBLE

BECAUSE OF THE WAY THEIR FLIGHT FEATHERS WORK.

AND IF YOU TAKE ONE OF THESE FEATHERS AND HAVE A LOOK,

YOU CAN ACTUALLY SEE THAT ON ONE SIDE,

THERE'S JUST MORE FEATHER.

AND IT'S THIS ASYMMETRY THAT ALLOWS HIM TO BE

SUCH AN AMAZING FLYER.

ON FLIGHT FEATHERS, ONE SIDE OF THIS KERATIN VEIN IS LARGER.

AS A BIRD FLIES, THIS LARGER PART OF THE VEIN

CATCHES THE AIR, ROTATING THE FEATHERS SLIGHTLY.

THIS TWISTS THE FEATHERS SO THEY INTERLOCK.

THIS THEN STOPS AIR PASSING THROUGH THEM,

AND IT'S THIS THAT GIVES THE WING LIFT AND THRUST.

THIS INTERLOCKING MEANS THAT TOGETHER,

ALL THE FEATHERS IN THE WING FORM A LARGE SURFACE AREA,

IMPERMEABLE TO THE AIR,

MEANING THE HIGHER PRESSURE UNDERNEATH KEEPS THE BIRD ALOFT.

ANOTHER TYPE OF FEATHER COMMON TO ALL BIRDS

IS THE CONTOUR FEATHER.

UNLIKE FLIGHT FEATHERS, THE VEIN ON CONTOUR FEATHERS

IS PRETTY SYMMETRICAL.

THESE FEATHERS COVER THE TORSO,

GIVING THE BIRD ITS AERODYNAMIC SHAPE.

FLIGHT FEATHERS AND CONTOUR FEATHERS

SHARE AN AMAZING MICRO STRUCTURE.

THE VEINS' FILAMENTS HAVE INTERLOCKING BARBS

WHICH MESH TOGETHER TO FORM AN EFFECTIVE SURFACE

FOR THE AIR TO SLIP OVER.

THIS ALLOWS CONTOUR FEATHERS TO CREATE A STREAMLINED SHAPE

AROUND THE BIRD'S BODY.

AND THERE'S ONE GROUP OF BIRDS OF PREY

WHICH TAKE FULL ADVANTAGE OF THIS AERODYNAMIC FEATURE.

WHEN THEY HUNT, SOME FALCONS

CAN REACH AN ASTONISHING 320 KILOMETERS PER HOUR.

AND I'M GOING TO SEE ONE OF THEM IN ACTION.

JEMIMA, THIS IS A BEAUTIFUL BIRD,

AND I'VE SEEN THESE IN THE WILD.

THIS IS A GYRFALCON, ISN'T IT?THAT'S RIGHT.

THESE ARE BUILT FOR SPEED AND BUILT TO KILL, RIGHT?

THEY ARE. THEY'VE GOT THESE LOVELY LONG, POINTED WINGS,

AS HAVE ALL THE FALCONS.

AND WE HAVE A SPECIAL WAY TO SHOW YOU

HOW THIS THING DOES FLY.

SO WE'VE GONE MODERN,

AND WE HAVE A ROBOTIC CROW, THE ROCROW.

SO WE'RE GONNA CHUCK UP A ROBOT, GET IT TO FLY,

AND SEE IF THIS BEAUTIFUL BEAST CAN TAKE IT DOWN?

THAT'S WHAT WE'RE GONNA DO.

BRILLIANT. I WANT TO SEE THIS.

♪♪

Garrod: JEMIMA USES THIS TECHNIQUE

TO TRAIN MANY OF HER FALCONS.

THESE BIRDS TYPICALLY HUNT

AT A HEIGHT OF AROUND 300 METERS,

PERFECT FOR SWOOPING DOWN ON THEIR PREY.

SO HE'LL HAVE TO CLIMB NOW, I GUESS,

TO GET ABOVE THE ROBOT, WON'T HE?

HE HAS TO CLIMB, AND THAT'S WHAT HE'S GOT TO LEARN.

HE'S QUITE YOUNG AND NOT, AS YET, VERY FIT,

AND IT'S A WINDY DAY FOR HIM.

Garrod: FALCONS DIVE AT THEIR PREY LIKE BULLETS,

OFTEN STUNNING OR EVEN KILLING THEM IN MID-AIR.

DURING THIS DIVE, THEIR POINTED WINGS

AND THE INTERLOCKING BARBS ON THEIR FEATHERS

MAKES THIS FAMILY OF BIRDS

AMONG THE FASTEST ANIMALS ON THE PLANET.

THE ROBOCROW DOESN'T STAND A CHANCE.

Garrod: YOU CAN SEE THOSE BIG, LONG FLAPS

FOLLOWED BY SOME REALLY QUICK, THRUSTING BEATS THERE.

YEAH.

HE'S JUST TRYING TO GET SOME SPEED.

AND HE DOESN'T STOP EITHER.

WHOA! -OOH, OOH, OOH!

GOOD BOY! OH!

HE JUST HIT -- OH, AND ROBOCROW'S DOWN.

AND DOWN HE GOES. GOOD BOY.

AND THIS IS WHAT THEY USE TO HUNT IN THE WILD.

WE SAW DIFFERENT TYPES OF FLIGHT THERE,

AND THAT LAST-SECOND HIT, USING THE FEATHERS,

USING THE WING SHAPE TO REALLY BRING ALL THOSE THINGS TOGETHER

AND TAKE DOWN ITS PREY.

WELL, I'M ALWAYS HAPPY WHEN NATURE TRASHES A ROBOT,

SO THAT WAS GREAT.

Garrod: FROM THE GROWTH OF SMALL KERATIN PROTRUSIONS,

IT'S THEIR SKIN WHICH HAS ENABLED BIRDS TO SOAR,

HOVER, DIVE, AND GLIDE THEIR WAY

TO DOMINATING THE SKIES.

BUT WITHOUT FEATHERS, HOW DO YOU GET INTO THE AIR?

LIVING IN THE RAINFORESTS OF AUSTRALIA AND INDONESIA,

SUGAR GLIDERS SPEND THEIR TIME IN THE TREETOPS,

GLIDING BETWEEN BRANCHES.

THESE MARSUPIALS USE WINGS MADE OF FLAPS OF SKIN

TO HARNESS THE POWER OF THE AIR,

ALLOWING THEM TO GLIDE UP TO 50 METERS.

BUT HOW THEY MANAGE TO STAY AIRBORNE FOR THIS DISTANCE

HAS REMAINED A MYSTERY.

TODAY, THIS WILL BE TESTED FOR THE FIRST TIME

BY DR. JORN CHENEY, A SPECIALIST IN ANIMAL FLIGHT ADAPTATIONS.

HEY, JORN.HEY, BEN, NICE TO SEE YOU.

YEAH, YOU TOO. WHO HAVE YOU GOT HERE?

THIS IS CHLOE.

I'VE NEVER SEEN A LIVE SUGAR GLIDER BEFORE.

HELLO.

I'M ABSOLUTELY FASCINATED BY THE STRUCTURE OF THEIR SKIN

BECAUSE THEY MOVE THROUGH THE AIR,

BUT THEY DON'T FLY IN A TRADITIONAL SENSE, DO THEY?

NO, NO, THEY'RE MORE GLIDERS THAN FLYERS.

AND TRADITIONALLY, WE THINK OF FLYING AS ANIMALS

THAT FLAP THEIR WINGS AND POWER THEMSELVES THROUGH THE AIR.

GLIDERS MOSTLY GO DOWN AND THEN SIDEWAYS.

IT'S SUPER WEIRD, BECAUSE THAT'S NOT HOW WE FLY.

WE DON'T SEE BIRDS FLY THAT WAY.

WE DON'T BUILD AIRCRAFTS THAT WAY.

AND SO I'M INTERESTED IN WHY SHE'S ABLE TO FLY SO WELL

WITH SUCH AN UNUSUAL SHAPE.

Garrod: FOR THIS EXPERIMENT,

WE'RE AT THE SPECIALIST FLIGHT RESEARCH CENTER

AT THE ROYAL VETERINARY COLLEGE IN HERTFORDSHIRE.

-I'LL RELIEVE HER FROM YOU. -THANK YOU.

CHLOE HAS BEEN HAND-REARED, AND HER HANDLER, SIMON,

IS GOING TO HELP WITH THE EXPERIMENT.

SO CHLOE'S GOING TO START ON THAT PLATFORM UP THERE.

SHE'S GONNA USE THAT AS A LAUNCH PLATFORM,

AND SIMON'S GONNA HOLD THAT AND COAX HER OFF

TO JUMP OVER TO YOU, JUST LIKE THAT,

WHERE YOU'LL BE STANDING OVER THERE.

JORN HAS SET UP FOUR ULTRA-HIGH-SPEED CAMERAS

TO RECORD CHLOE'S GLIDING.

CHLOE TAKES HER PLACE ON THE LAUNCHPAD,

AND I DO MY BEST TO IMPERSONATE A TREE.

Simon: [ SMOOCHING ]

OOH, OOH, OOH, OOH, OOH. SHE'S THINKING ABOUT IT.

OOH, OOH.

[ LAUGHS ]

PERFECT. [ LAUGHS ]

Garrod: CHLOE GETS INTO THE SWING OF THINGS IMMEDIATELY.

COME ON, THEN.

ALTHOUGH HER AIM NEEDS A LITTLE WORK.

[ LAUGHS ]

THIS IS ONE OF THE WEIRDER EXPERIMENTS

I'VE EVER DONE, I'M NOT GONNA LIE.

OH! [ LAUGHS ]

I LOVE THAT WE'RE ACTUALLY DOING SCIENCE

WHILST TRYING TO CATCH A SUGAR GLIDER.

THIS IS BRILLIANT.

Garrod: IT'S THE SHAPE THAT CHLOE'S FLEXIBLE SKIN WINGS

TAKE IN THE AIR THAT WILL TELL JORN

A LOT ABOUT HOW SHE'S USING THEM.

WELL DONE, LITTLE ONE.

AND IN ORDER TO SEE THIS,

HE'S CREATED A 3D MODEL OF CHLOE'S WINGS WITH HIS CAMERAS.

WHAT HAVE THE RESULTS SHOWN?

SO THAT BEAUTIFUL THING IS CHLOE,

JUST THE TOP SURFACE OF HER.

YEP.

WHAT YOU'RE ABLE TO PICK UP FROM THIS

IS THE FULL 3D SHAPE THAT SHE'S USING WHEN SHE GLIDES.

AND THAT'S IMPORTANT BECAUSE THE AERODYNAMICS

ARE ENTIRELY DETERMINED BY THE SHAPE.

BUT ALSO, SHE'S NOT FLAT. SHE'S CURVED.

YEAH, SHE'S GOT A LOT OF CURVATURE.

Garrod: JORN HAS WORKED OUT THAT CHLOE'S WINGS CURVED,

OR BILLOWED, BY A SURPRISING AMOUNT,

OVER THREE TIMES MORE THAN THE WINGS OF A GLIDING BIRD.

ALL OF THAT BILLOWING HELPS GUIDE THE AIR DOWNWARD

AND BACKWARD, PRODUCING LIFT.

THE MORE BILLOWING YOU GET,

THE MORE AERODYNAMIC FORCE YOU'RE PRODUCING.

SO IF THE WING WASN'T BILLOWING LIKE THAT,

SHE'D BE A MUCH WORSE FLYER.

WHAT'S ALSO CLEAR IS THAT CHLOE IS CONTROLLING THIS BILLOWING.

THE MUSCLES IN THE MIDDLE OF THE SKIN FLAPS ARE RELAXED,

WHILE THE MUSCLES AROUND THE EDGE HAVE BEEN TENSED.

Garrod: SO THIS FLEXIBLE SKIN --

WE DEFINITELY DON'T SEE THAT WITH BIRDS, DO WE?

WE DON'T SEE IT WITH BIRDS, BUT WE DO SEE IT

WITH EVERY OTHER GLIDING MAMMALIAN LINEAGE.

ALL HAVE, FOR WHATEVER REASON,

CONVERGED UPON THE IDEA OF USING SKIN AS A WING

AND THEN EMBEDDING MUSCLE INTO IT.

AND WE'RE ABLE TO FIGURE OUT THAT THE MUSCLE

ISN'T THE ONLY THING SUPPORTING THE BODY WEIGHT.

THE SKIN IS ACTUALLY DOING QUITE A BIT.

Garrod: THERE'S STILL A LOT MORE WORK TO DO TO REALLY UNDERSTAND

WHAT IS GOING ON WITH GLIDING ANIMALS LIKE CHLOE.

BUT ONE DAY, JORN IS HOPING EXPERIMENTS LIKE THIS

COULD PAVE THE WAY FOR NEW AIRCRAFT TECHNOLOGY

USING FLEXIBLE MATERIAL FOR WINGS.

SKIN'S ADAPTABILITY IS UNPARALLELED.

ANIMALS HAVE USED THEIR SKIN TO MASTER MOVEMENT

ON EVERY SURFACE, PATCH OF SKY, AND BODY OF WATER ON EARTH.

[ SPLASHING ]

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