All language subtitles for 1 Secrets.Of.Skin

♪♪

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 IT'S HAIRLESS.

THE SKIN'S TOTALLY DIFFERENT.

NOW, GROUNDBREAKING
NEW SCIENCE...

THIS IS REALLY QUITE REMARKABLE.

IT SHOULD BE A GAME CHANGER
FOR SO MANY PEOPLE.

[ RATTLING ]THAT SOUND! OH!

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

...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
EXTRASENSORY ABILITIES.

WE'RE EVEN DISCOVERING
THE COMPLEX ECOSYSTEM

LIVING ON OUR SKIN.

JIM, THAT'S AWFUL.
IT REALLY IS.

IN THIS EPISODE, I'LL REVEAL
HOW SKIN'S AMAZING VERSATILITY

HELPS FRIGATEBIRDS
ATTRACT A MATE...

♪♪

...MEANS FROGS
DON'T HAVE TO RELY

ON THEIR LUNGS TO BREATHE...

AND LETS MICROSCOPIC ANIMALS
LIVE ON OUR FACES --

ANIMALS THAT COULD CHANGE
THE STORY OF OUR EVOLUTION.

I'LL EXPLORE HOW SKIN'S
UNIQUELY ADAPTABLE STRUCTURE

ALLOWS VERTEBRATES TO OVERCOME

SOME OF LIFE'S
GREATEST CHALLENGES.

I'M GOING TO REVEAL
THE SECRETS OF SKIN.

♪♪

THERE ARE MORE THAN
66,000 SPECIES

OF VERTEBRATES ALIVE
ON THE PLANET TODAY.

THEY'VE CONQUERED THE WATER,
LAND, AND AIR,

AND HAVE EVOLVED INTO A DAZZLING
ARRAY OF SHAPES,

SIZES, AND COLORS.

AND IN MY OPINION, IT'S SKIN,
THE LARGEST ORGAN IN ANY ANIMAL,

THAT HOLDS THE KEY
TO THIS DIVERSITY AND SUCCESS.

OVER 500 MILLION YEARS
OF VERTEBRATE EVOLUTION,

SKIN'S INCREDIBLE ADAPTABILITY

HAS ENABLED IT
TO BECOME TOUGH...

FLEXIBLE...

SENSITIVE...

AND COLORFUL.

IT CAN GROW FEATHERS,
SCALES, HAIR...

AND EVEN TEETH.

BUT THAT'S JUST THE TIP
OF THE ICEBERG.

♪♪

THE KEY TO THIS INCREDIBLE
VERSATILITY

IS A REMARKABLE BLUEPRINT

THAT FORMS
THE BASIS OF VERTEBRATE SKIN.

FISH, REPTILES, AMPHIBIANS,
MAMMALS, AND BIRDS

ALL SHARE THE SAME
BASIC SKIN STRUCTURE.

ON THE SURFACE, THE EPIDERMIS,

MADE OF A FEW THIN LAYERS
OF PROTECTIVE CELLS.

BENEATH THAT, THE DERMIS,
RICH IN GLANDS,

NERVES, AND BLOOD VESSELS,

WHERE HAIR, FEATHERS,
AND SCALES ARISE.

AND THEN FINALLY,
THE SUBCUTANEOUS FAT LAYER,

A BED OF FATTY TISSUE
THAT HELPS INSULATE THE BODY.

ADAPTATIONS IN THE FORM
AND FUNCTION

OF THESE THREE BASIC LAYERS

HAVE LED TO THE DAZZLING RANGE
OF SKIN TYPES

EXHIBITED BY VERTEBRATES TODAY.

AND THE STORY STARTS
WITH THE OUTERMOST LAYER --

THE EPIDERMIS.

THE EPIDERMIS IS THE FINAL,

THIN BARRIER BETWEEN AN ANIMAL
AND ITS ENVIRONMENT.

ON MY BODY, IT VARIES BETWEEN
ONE MILLIMETER THICK

ON THE SOLES OF MY FEET

TO JUST 30 MICROMETERS
HERE ON MY EYELIDS.

ON MY LITTLE FRIEND HERE,
IT CAN BE EVEN THINNER,

BETWEEN 50 AND 12 MICROMETERS.

IT'S ESTIMATED THAT THE AVERAGE
HUMAN EPIDERMIS

CONTAINS UP TO 180 BILLION
CELLS.

ITS MAIN FUNCTION IS TO PROTECT
US FROM THE OUTSIDE WORLD,

AND IT IS CONSTANTLY
REPLACING ITSELF.

I'M LOSING 20 MILLION EPIDERMAL
CELLS EVERY SINGLE HOUR.

AND IN ROUGHLY A MONTH'S TIME,

MY ENTIRE EPIDERMIS
WILL EFFECTIVELY BE BRAND-NEW.

THIS MEANS MAMMAL SKIN
IS A LITTLE BIT

LIKE A FLAKY CONVEYOR BELT.

THIS ENDLESS CYCLE OF EPIDERMAL
RENEWAL HAS TWO BENEFITS.

DAMAGED SKIN FALLS AWAY TO BE
REPLACED BY NEW, HEALTHY CELLS.

AND BECAUSE OUR EPIDERMIS
IS CONSTANTLY RENEWING,

IT CAN GROW WITH US.

BUT THIS ISN'T THE CASE
FOR ALL VERTEBRATES,

PARTICULARLY REPTILES,
BECAUSE THEY HAVE A PROBLEM.

REPTILES' OUTER LAYER OF SKIN
DOESN'T GROW WITH THEM,

SO THEY HAVE TO SHED THEIR
ENTIRE EPIDERMIS IN ONE GO.

IT'S SIMPLY REPLACED BY A BIGGER
VERSION GROWING UNDERNEATH.

♪♪

A SNAKE'S SIMPLER BODY SHAPE
MAKES THIS PROCESS MUCH EASIER.

ADULT SNAKES DO THIS
UP TO FOUR TIMES A YEAR,

ALTHOUGH YOUNG,
FAST-GROWING INDIVIDUALS

CAN SHED EVERY TWO WEEKS.

THIS SNAKE HAS JUST SHED.

HER SKIN CAME OFF
LIKE ONE BIG SOCK,

AND EVERY SINGLE BIT OF HER
WAS REPLACED IN ONE GO,

INCLUDING THE SCALES
OVER HER EYES.

LIZARDS AND SNAKES
SHED LIKE THIS

BECAUSE REPTILE SKIN
IS TOUGHENED

BY LARGE AMOUNTS OF A FIBER
MADE IN THE EPIDERMIS --

KERATIN,
A COMPLEX OF TWISTED PROTEINS.

IT'S ONE OF THE TOUGHEST
NATURAL MATERIALS IN EXISTENCE.

FOUND IN ALL VERTEBRATES' SKIN,
IT'S INCREDIBLY VERSATILE.

BUT JUST HOW TOUGH IS IT?

ONE PLACE KERATIN IS FOUND
IN HIGH CONCENTRATIONS

IS THE HARD OUTER WALL
OF A HORSE'S HOOF.

WILD STALLIONS USE THEIR HOOVES
AS WEAPONS

IN VIOLENT BATTLES OVER MARES.

[ HORSE NEIGHS ]

THEY'RE CAPABLE
OF DELIVERING A KICK

WITH A FORCE OF UP TO A TON,
WITH BONE-SHATTERING RESULTS.

[ HORSES NEIGHING ]

WITH THIS IN MIND,

I NEED A SAFE WAY TO SEE
THOSE TOUGH HOOVES CLOSE UP.

SO I'VE COME TO HILL LIVERY
STABLES NEAR BRISTOL

TO MEET FARRIER DAN DOWNTON.

WHO HAVE WE GOT HERE?

THIS IS JASPER.

HE'S COME IN
FOR A NEW SET OF SHOES.

I'M REALLY INTERESTED
TO SEE HOW IT'S DONE.

SHALL WE GET ON WITH IT, THEN?YEAH. LET'S GIVE A GO.

SO, FIRST OF ALL,
WE'RE GONNA TAKE THE SHOE OFF.

YEAH.

DAN, THAT LOOKS QUITE BRUTAL,

BUT JASPER'S NOT
FEELING THAT, IS HE?

NO. HE'S GOT QUITE
A LOT OF FOOT THERE,

AND WE'RE NOT TOUCHING
ANY SENSITIVE STRUCTURES,

SO IT'S FINE.

AND THAT'S THE NAIL
WE CAN SEE THERE, ISN'T IT?

YEAH.
SO THAT'S THE HOOF WALL.

THIS IS THE SOLE,
AND THIS IS THE FROG.

OKAY.

A HORSE'S HOOF EVOLVED
FROM A SINGLE TOENAIL,

LIKE ONE OF OURS.

AND ITS DENSE WALL OF KERATIN

GROWS OUT OF THE EPIDERMIS
IN A SIMILAR WAY.

THE KERATIN IN AN UNSHOD HOOF

HAS TO WITHSTAND
INCREDIBLE FORCES.

A GALLOPING HORSE CAN GENERATE
1,000 KILOGRAMS

THROUGH EACH FOOT.

GIVE THAT A RASP.

HE HASN'T GOT A LOT
OF FOOT ON IT.

ONCE THE OLD SHOE'S OFF,
DAN TRIMS THE HOOF.

SO THIS IS LIKE
A BIG NAIL FILE?

SO YOU'VE BASICALLY GIVEN JASPER
A HUGE MANICURE RIGHT NOW?

THAT'S IT.[ LAUGHS ]

Garrod: JUST LIKE OUR NAILS,
A HORSE'S HOOVES

DON'T CONTAIN NERVES
OR BLOOD VESSELS.

THE KERATIN WALL GROWS
FROM THE SKIN

AT AROUND SIX MILLIMETERS
A MONTH --

AN EVOLUTIONARY RESPONSE
TO THE CONSTANT WEAR AND TEAR

HOOVES EXPERIENCE.

HOOVES ARE SO IMPORTANT

TO THE SURVIVAL
AND WELL-BEING OF A HORSE

THAT FOR AT LEAST 2,000 YEARS,

WE'VE ENHANCED KERATIN'S
TOUGHNESS WITH IRON,

SHOEING DOMESTICATED HORSES

TO MAINTAIN THE VITAL INTEGRITY
OF THEIR HOOVES.

IT'S NOT JUST HORSES THAT RELY
ON KERATIN'S DURABILITY.

MANY OTHER ANIMALS
HAVE EXPLOITED

ITS AMAZING ATTRIBUTES.

♪♪

PANGOLINS, LIKE THIS ONE HERE,

ARE COVERED IN OVERLAPPING
KERATIN SCALES.

THEY GROW OUT OF THE EPIDERMIS
AND FORM THIS TOUGH,

BUT FLEXIBLE SUIT OF ARMOR.

IF THE PANGOLIN IS ATTACKED,

IT CURLS INTO A BALL
TO PROTECT ITSELF.

AND EVEN A LION'S TEETH
AND CLAWS CAN'T GET THROUGH

THOSE 2-MILLIMETER-THICK SCALES.

KERATIN ISN'T JUST PRODUCED
FOR PROTECTION.

VERTEBRATES USE IT IN A HUGE
RANGE OF SKIN-BASED STRUCTURES.

IT'S A KEY COMPONENT
IN ALL HAIR AND QUILLS...

ALL FEATHERS AND SCALES...

AND CLAWS AND FINGERNAILS.

♪♪

THERE ARE 30 DIFFERENT FORMS
OF KERATIN IN MAMMALS ALONE.

AT ITS MOST CHEMICALLY COMPLEX
AND TOUGH,

IT TURNS A RHINO HORN
INTO A BATTERING RAM.

[ RHINOS GRUNTING ]

♪♪

WHILE THE MAIN FUNCTION
OF THE EPIDERMIS IS PROTECTION,

THE LAYER BELOW,
THE DERMIS,

COMBINES INTENSE
BIOLOGICAL ACTIVITY

WITH SOME EXTRAORDINARY
PHYSICAL ATTRIBUTES.

[ FRIGATEBIRDS CALLING ]

THIS IS A MALE GREAT FRIGATEBIRD
FROM THE GALAPAGOS ISLANDS.

HE'S JUST WON A HOTLY CONTESTED
PATCH OF GROUND TO NEST ON.

NOW HE NEEDS A MATE.

FEMALE FRIGATEBIRDS
ARE GLIDING OVERHEAD.

SOMEHOW, HE MUST ATTRACT
THEIR ATTENTION

WITHOUT ABANDONING HIS HARD-WON
BIT OF TURF.

♪♪

HIS SOLUTION IS THIS HUGE,
INFLATED BALLOON OF SKIN

ON HIS THROAT.

CALLED A GULAR SAC,
IT'S ALMOST AS TALL AS HE IS

AND CLEARLY VISIBLE
TO THE CIRCLING FEMALES.

[ FRIGATEBIRDS CALLING ]

HE ADDS TO THE DRAMATIC EFFECT
BY SHAKING IT FROM SIDE TO SIDE

AND CLACKING HIS BEAK.

EVENTUALLY, HIS LONELY-HEARTS AD
DOES THE TRICK

AND A FEMALE JOINS HIM
AT THE NEST SITE.

♪♪

JOB DONE.

HIS GULAR SAC DEFLATES
AND ALL BUT DISAPPEARS.

THE KEY TO A MALE FRIGATEBIRD'S
AMAZINGLY STRETCHY SKIN

IS DOWN TO A FIBROUS PROTEIN

THAT'S FOUND IN THE DERMIS
OF ALL VERTEBRATES.

IT'S CALLED ELASTIN.

NAMED FOR ITS ELASTIC PROPERTIES
AND LOOKING AND BEHAVING

LIKE A MESH OF TIGHTLY COILED
MICROSCOPIC SPRINGS,

ELASTIN PULLS STRETCHED SKIN
BACK INTO SHAPE.

HUMAN ELASTIN PRODUCTION
SLOWS DOWN AS WE GET OLDER.

AND THIS MEANS OUR SKIN
NOT ONLY GETS LESS STRETCHY,

BUT STARTS TO DEVELOP WRINKLES.

♪♪

THE IMPRESSIVE ELASTICITY
OF THE DERMIS

HAS LED TO SOME EXTRAORDINARY
ADAPTATIONS

ACROSS THE VERTEBRATE WORLD,

FROM KANGAROO POUCHES
TO BAT WINGS.

♪♪

AND NONE MORE SO THAN FROGS.

DURING THE BREEDING SEASON,

MALE FROGS' VOCAL SACS
COMBINE ELASTIN

AND VERY THIN SKIN
TO AMPLIFY THEIR MATING CALLS.

THE AMPHIBIAN DERMIS IS
REMARKABLE FOR ANOTHER REASON.

♪♪

MORE THAN ANY OTHER VERTEBRATE,

THEY RELY ON THEIR SKIN
FOR THE UPTAKE OF OXYGEN.

AMPHIBIANS,
LIKE THIS AFRICAN BULLFROG,

USE THEIR THIN, PERMEABLE SKIN
EFFECTIVELY TO BREATHE IN WATER

AS WELL AS ON LAND.

THEIR SKIN HAS EVOLVED
TO LET OXYGEN PASS

THROUGH THE CELLS
OF THE EPIDERMIS AND DERMIS

AND INTO THE BLOODSTREAM.

THEY CAN GET AS MUCH AS 20% OF
THEIR OXYGEN THROUGH THEIR SKIN.

♪♪

[ LAUGHS ]

ONE FROG HAS TAKEN THIS
TO THE EXTREME.

THE TITICACA FROG,

FOUND IN RIVERS AND LAKES
HIGH IN THE ANDES,

IS COVERED IN FOLDS
OF EXTRA SKIN.

A DENSE NETWORK OF CAPILLARIES
IN THE DERMIS OF THESE FOLDS

ALLOWS THE FROG TO ABSORB
ALL THE OXYGEN IT NEEDS

FROM THE WATER,

MEANING IT NEVER HAS TO SURFACE
TO BREATHE.

BUT THERE ARE DRAWBACKS
TO THIS TYPE OF RESPIRATION.

IN ORDER TO SURVIVE, AMPHIBIANS
NEED TO LIVE IN DAMP PLACES,

WHERE THEIR SKIN REMAINS MOIST.

IF IT DRIES OUT, IT MEANS THAT
GASES CAN'T DIFFUSE ACROSS IT

AND THEY SUFFOCATE.

ALONGSIDE ITS IMPRESSIVE
PHYSICAL ATTRIBUTES,

THE DERMIS IS ALSO A HIVE
OF BIOLOGICAL ACTIVITY.

SPECIALIZED GLANDS PRODUCE A
HUGE ARRAY OF NATURAL COMPOUNDS,

WHICH FURTHER ENHANCE
THE SKIN'S VERSATILITY.

AND I'VE GOT A NEAT, LOW-TECH
WAY TO DEMONSTRATE THIS.

THESE ARE CAMPHOR BOATS,

AND A TINY CAMPHOR CRYSTAL
ON THE BACK OF EACH ONE

HAS THEM SHOOTING ACROSS THE
SURFACE OF THE WATER LIKE MAGIC.

OF COURSE IT'S NOT MAGIC.

CAMPHOR IS A PUNGENT CHEMICAL
HARVESTED FROM CAMPHOR TREES.

IT DISSOLVES IN WATER,
ALTERING THE SURFACE TENSION

AND PUSHING THE LITTLE BOATS
FORWARD.

ALL IT TAKES TO STOP THEM
IS A THIN LAYER

OF GREASE ON THE WATER,

AND I KNOW JUST WHERE
TO FIND SOME.

♪♪

IN COMMON WITH MOST MAMMALS,

MY SKIN IS COATED
IN A THIN LAYER OF OIL.

THIS IS A WAXY SUBSTANCE
CALLED SEBUM

THAT HELPS LUBRICATE
AND WATERPROOF MY SKIN.

IT'S PRODUCED
BY SEBACEOUS GLANDS

IN THE DERMIS OF ALL MAMMALS.

THESE ARE OFTEN FOUND
NEXT TO HAIR FOLLICLES,

WHICH IS WHY OUR HAIR
GETS GREASY.

WHILE WE HAVE AN ESTIMATED
2 MILLION SEBACEOUS GLANDS

ALL OVER OUR SKIN,

IT'S STILL A MYSTERY

WHY THEY'RE MOST ABUNDANT
ON OUR SCALP AND FACES.

MAMMALS
AREN'T THE ONLY VERTEBRATES

PRODUCING NATURAL OILS
IN THE DERMIS.

BIRDS HAVE SEBACEOUS GLANDS,
TOO.

BUT INSTEAD OF LOTS OF
SMALL GLANDS ALL OVER THE SKIN,

THEY'VE EVOLVED ONE BIG ONE.

AND IF WE'RE REALLY CAREFUL,
WE CAN LOOK AT THIS CONURE'S...

[ CONURE SQUAWKS ]BECAUSE -- HELLO! --

JUST AT THE TOP OF THE TAIL,
YOU CAN SEE A LITTLE PATCH

THAT LOOKS LIKE IT'S A BUNCH
OF SOGGY FEATHERS.

THAT'S THE PREEN GLAND.

AND IT'S THIS THAT PRODUCES OIL

WHICH THE BIRD THEN SPREADS
AROUND ITS BODY

USING ITS BEAK AND HEAD.

BIRDS USE THIS
DERMIS-PRODUCED OIL

FOR LOTS OF DIFFERENT REASONS --

KEEPING FEATHERS SUPPLE
FOR FLYING,

SENDING ODOR-BASED
CHEMICAL MESSAGES

TO POTENTIAL MATES OR RIVALS.

IT ALSO HELPS
TO KEEP FEATHER COLORS VIVID.

MANY DIVING BIRDS
HAVE LARGE PREEN GLANDS,

WHICH SUGGESTS
IT ALSO PLAYS A VITAL ROLE

IN WATERPROOFING THEIR FEATHERS,

ALTHOUGH BIOLOGISTS
ARE UNSURE OF EXACTLY HOW.

PREEN OIL IS AN IMPRESSIVE,

BUT MYSTERIOUS
MULTIPURPOSE SUBSTANCE.

AND THE DERMIS STILL
HAS MORE SURPRISES IN STORE.

♪♪

IN ANCIENT MAMMAL ANCESTORS

LIVING MORE THAN
250 MILLION YEARS AGO,

SCIENTISTS BELIEVE
THE DERMIS EVOLVED

TO SECRETE SOMETHING
EXTRAORDINARY -- MILK.

THERE ARE FOUR DIFFERENT
TYPES OF GLAND

IN THE MAMMALIAN DERMIS,

AND IT'S THOUGHT AN ADAPTATION
OF ONE, THE SWEAT GLAND,

LED TO THIS VITAL STEP
IN MAMMAL EVOLUTION.

WE HAVE A ROUGH IDEA
OF HOW THAT MIGHT HAVE WORKED

FROM PLATYPUS AND ECHIDNAS,

LIKE THIS LITTLE GUY HERE
FROM AUSTRALIA.

NOW, THESE ARE UNUSUAL MAMMALS
IN THAT THEY LAY EGGS,

AND THEY FEED THEIR OFFSPRING
FROM MILK

THAT'S SECRETED TO THE SURFACE
OF THE SKIN

BY COLLECTIONS OF PORES.

THIS MIGHT HAVE BEEN AN EARLY
STEP INTO THE DEVELOPMENT

OF DEDICATED NIPPLES
AND MAMMARY GLANDS

AS WE SEE
IN MOST MAMMALS ALIVE TODAY.

THE VERSATILITY OF THE DERMIS

ALLOWS IT TO MAKE AN ARRAY
OF UNIQUE COMPOUNDS

THAT HAVE SHAPED
VERTEBRATE EVOLUTION.

AND THERE IS ONE MORE --
COLLAGEN,

A PROTEIN WITH INCREDIBLE
TENSILE STRENGTH

WHICH IS FOUND
IN EVERY VERTEBRATE DERMIS.

ONLY NOW ARE WE UNDERSTANDING
THE FAR-REACHING EFFECT

IT COULD HAVE ON OUR LIVES.

I'M GOING TO SEE BIOENGINEER
DR. CLAIRE HIGGINS.

SHE'S TESTING A DISC
OF HUMAN FOOT SKIN

TO SEE HOW IT RESPONDS
TO A BIT OF WEAR AND TEAR.

Higgins:
SO, THE MACHINE COMPRESSES
THE PIECE OF SKIN,

AND WE MEASURE THE AMOUNT
OF DEFORMATION IN THE TISSUE

AS TO HOW MUCH THE TISSUE
IS CHANGING SHAPE.

THE DISC OF FOOT SKIN
IS REPEATEDLY SQUASHED

UP AND DOWN
AND SIDE TO SIDE,

MIMICKING THE FORCES
PRODUCED BY WALKING.

AND WHAT HAVE THE RESULTS
SHOWN SO FAR?

SO WITH COMPRESSION, FOOT SKIN
DEFORMS BY ABOUT 15%

WHEREAS BODY SKIN CHANGES SHAPE
BY ABOUT 25%.

AND THEN, WHEN WE LOOK AT
SHEAR FORCES,

FOOT SKIN DEFORMS BY ABOUT 40%,

WHILE LEG SKIN ACTUALLY DEFORMS
BY AS MUCH AS 150%.

CLAIRE'S TESTS REVEAL THAT

WHEN IT COMES TO DEALING
WITH WEAR AND TEAR,

THE SKIN ON OUR FEET
SIGNIFICANTLY OUTPERFORMS

THE SKIN
ON THE REST OF OUR BODIES.

TO FIND OUT WHAT MAKES FOOT SKIN
SO RESILIENT,

CLAIRE'S USING LASER MICROSCOPY.

SO WE'RE ACTUALLY IMAGING
COLLAGEN FIBERS,

AND WE'RE INTERESTED
IN COLLAGEN

BECAUSE IT MAKES UP
ABOUT 90% OF THE SKIN DERMIS,

AND IT'S REALLY
THE STRUCTURAL PROTEIN

THAT CONTRIBUTES
TO THE INTEGRITY OF THE SKIN.

FIBERS OF COLLAGEN
RUNNING THROUGH THE DERMIS

ARE WHAT GIVE VERTEBRATE SKIN
ITS TENSILE STRENGTH.

SO YOU CAN SEE,
IN THIS IMAGE HERE,

THIS IS COLLAGEN IN FOOT SKIN.MM-HMM.

AND THIS IMAGE ON THE RIGHT
IS COLLAGEN IN LEG SKIN.

THE FOOT SKIN
OWES ITS IMPRESSIVE TOUGHNESS

TO THIS DENSE NETWORK
OF COLLAGEN.

THE IMAGES SHOW THAT
THE COLLAGEN FIBERS IN FOOT SKIN

ARE MUCH THICKER
THAN THE ONES IN LEG SKIN.

THEY'RE ALSO ABOUT FOUR TIMES
BRIGHTER, WHICH IS SIGNIFICANT.

THAT BRIGHTNESS ACTUALLY IS
AN INDICATION OF TENSILE STATE.

THE FIBERS IN FOOT SKIN
ARE PRETENSED ALMOST.

SO BASICALLY THESE ARE EVER
READY LITTLE BUNDLES OF COLLAGEN

IN ANTICIPATION
FOR THIS HEAVY WEAR AND TEAR

THAT WE'RE NOT SEEING
ELSEWHERE IN THE BODY?

♪♪

CLAIRE'S GROUNDBREAKING
RESEARCH HAS REVEALED

THAT OUR SKIN STRUCTURE VARIES
WITH THE JOB IT HAS TO DO.

HER ULTIMATE AIM IS TO REPLICATE

THE DURABILITY OF FOOT SKIN

IN SKIN
ON OTHER PARTS OF THE BODY,

CHANGING LIVES IN THE PROCESS.

THERE ARE SOME CIRCUMSTANCES,
SUCH AS AFTER AMPUTATION,

THAT SKIN ON A STUMP
IS REQUIRED TO BE LOAD-BEARING,

BUT IT'S NOT DESIGNED TO BE.

SO WE'RE HOPING THAT WE CAN
TRY TO RE-ENGINEER SKIN,

SUCH AS STUMP SKIN,
TO MAKE IT STRONGER

AND MAKE IT CAPABLE
OF BEING LOAD-BEARING.

SO YOU'RE TALKING ABOUT
DEVELOPING SKIN ON PEOPLE

WITH DISABILITIES
OR INJURIES HERE?

YEAH, RE-ENGINEERING SKIN
ON THE STUMP, ESSENTIALLY.

THIS IS REALLY
QUITE REMARKABLE,

AND IT SHOULD BE A GAME CHANGER
FOR SO MANY PEOPLE.

OH, WE HOPE SO.
YEAH, ABSOLUTELY.

CLAIRE'S DISCOVERIES
ARE SHEDDING NEW LIGHT,

NOT JUST ON THE POTENTIAL
OF HUMAN SKIN,

BUT THE VERSATILITY
OF SKIN ITSELF.

IT'S ALSO A CLEAR DEMONSTRATION

OF JUST HOW MUCH
WE STILL HAVE TO LEARN.

ANOTHER REMARKABLE DISCOVERY
ABOUT HUMAN SKIN

COULD CHANGE
OUR VIEW OF EVOLUTION.

IT INVOLVES LOOKING FOR
AN ANIMAL

THAT LIVES ON AND IN OUR SKIN.

THEY'RE SO SMALL
THAT YOU CAN'T FEEL THEM

OR SEE THEM WITH THE NAKED EYE,

BUT MOST OF US DO HAVE THEM.

SO I'M OFF TO SEE
WHETHER I CAN FIND MINE.

THEY'RE SKIN MITES.

AND I'VE COME TO MEET
DR. DAVE PATTON,

WHO'S GOING TO HELP ME
TRACK MINE DOWN.

HI, DAVE.
HELLO.

SO WE'RE GONNA LOOK FOR MITES
ON MY FACE, ARE WE?

YEAH. WE'RE GONNA USE
AN INTERESTING TECHNIQUE

INVOLVING SUPERGLUING YOUR HEAD
TO A GLASS SLIDE.

[ LAUGHS ]

YOU SAY IT LIKE
IT'S SUCH A COMMON THING.

OKAY, SO WE'VE LITERALLY GOT A
GLASS SLIDE AND SOME SUPERGLUE.

YES.

OKAY.
RIGHT.

SO ALL WE DO IS PUT SOME GLUE
ON THE SLIDE

AND THEN PRESS IT ONTO
YOUR FOREHEAD FOR A MINUTE.

THEN IT'LL REMOVE
SOME OF YOUR FOREHEAD

AND HOPEFULLY
SOME SKIN MITES.

NOT MUCH OF MY FOREHEAD,
THOUGH, RIGHT?

UM...A MILLIMETER.

[ CHUCKLES ]

MITES LIVE IN GREATER
CONCENTRATIONS ON OUR FACES

THAN ANYWHERE ELSE,

PARTICULARLY ON OUR CHEEKS
AND FOREHEADS.

YOU READY?
I THINK SO.

RIGHT, OKAY.

OKAY.
CAN YOU HOLD THAT IN PLACE?

YEAH.

WHILE THE 60 SECONDS COUNT DOWN,
I WANT TO CHECK SOMETHING.

HAVE YOU DONE THIS
TO YOURSELF?

YES. YES.

HAVE YOU FOUND ANY?

WE HAVE FOUND ONE.
[ LAUGHS ]

THAT'S NOT
A VERY HIGH HIT RATE.

SO TO BE ON THE SAFE SIDE,
WE'LL NEED SOME BACKUP SAMPLES.

I THINK IN THAT CASE, THEN,
WHAT I MIGHT DO

IS TO GET SLIDES AND SAMPLES
FROM ALL THE CREW, AS WELL.

WHY NOT? [ LAUGHS ]

COME ON, GUYS!
[ CHUCKLES ]

AND SO THE CREW BRAVELY SUBMITS
TO THE SUPERGLUE TREATMENT.

JUST PRESS THAT ON.
THANK YOU.

THANK YOU.

♪♪

AAH!

SORRY.THAT DIDN'T HURT.

WE HAVE GOT A NICE VARIETY OF
PEELED SKIN ON THERE RIGHT NOW.

SO NOW WE'VE PUT THOSE
UNDER A MICROSCOPE

AND WE SEE WHETHER WE CAN FIND

THESE LITTLE FACE MITES
STUCK ON THE SUPERGLUE?

YEAH. THAT'S THE PLAN.

WELL,
LET'S SEE IF WE CAN FIND SOME.

GOOD LUCK, TEAM.

♪♪

DAVE PUTS MY SAMPLE IN A
SCANNING ELECTRON MICROSCOPE,

AND WITHIN MINUTES,

I'M LOOKING AT THE INSIDE
OF MY SKIN MAGNIFIED 200 TIMES.

IT'S LIKE A REALLY HORRIBLE
TREASURE TRAIL,

'CAUSE I DON'T WANT
TO FIND WHAT'S HIDING.

[ BOTH LAUGHING ]

RIGHT, SO, TO SEARCH,
I'M JUST GOING TO MOVE

ONE SCREEN AT A TIME.

AND WE'RE LOOKING FOR
A LITTLE HEAD

THAT'S POPPING OUT NEXT
TO THE HAIR ITSELF, AREN'T WE?

YEAH, IN THE SAME PORE,
SO, LIKE, PARALLEL TO THE HAIR,

LOOKING VERY SIMILAR
TO THE HAIR.

BUT HOWEVER HARD WE SEARCH,

WE JUST DON'T FIND
ANY SIGNS OF LIFE.

SO WHAT I THINK WE SHOULD DO
IS HAVE A LOOK

AT SOME OF THE OTHER
FILM CREW MEMBERS

TO SEE WHAT THEIR SKIN'S LIKE.

SO WHO HAVE WE GOT HERE,
THEN, DAVE?

ANDY, THE SOUND MAN.

THERE'S A PORE THERE
WITH HAIR COMING OUT OF IT.

IT'S PROBABLY JUST A BIG BIT
OF FOLLICLE THERE

BELONGING TO THIS HAIR.

♪♪

DAVE LOOKS EVEN CLOSER,
AND BINGO.

THAT'S TEMPTING.
LOOK. LOOK AT THAT.

THERE APPEAR
TO BE 1, 2, 3 DEMODEX.

ANDY NOT ONLY HAS MITES.
HE'S GOT LOADS OF THEM.

SO YOU'VE GOT EVIDENCE

OF THREE LITTLE MITES
ON ONE HAIR STRAND

FROM ANDY'S SAMPLE HERE?

IT LOOKS LIKE IT.

WHAT WE'VE FOUND
ARE DEMODEX MITES --

TINY, HARMLESS ARACHNIDS
THAT LIVE ON MY,

YOUR, AND ANDY
THE SOUND MAN'S SKIN.

THEIR LONG, THIN BODIES
HELP THEM SLIDE

INSIDE OUR HAIR FOLLICLES,

WHERE THEY CLING ON
WITH EIGHT STUMPY CLAWS.

THEY SPEND THEIR TIME
HIDDEN AWAY,

FEEDING ON OILS
MADE IN THE DERMIS

AND ALL THOSE DEAD
EPIDERMAL CELLS.

IF THAT WASN'T BAD ENOUGH,

THESE LITTLE ANIMALS
ARE LIGHT-SENSITIVE

AND ONLY COME OUT AT NIGHT,

WHEN THEY MATE
ON OUR FACES.

♪♪

THE ONLY TIME WE DON'T HAVE
DEMODEX MITES

IS WHEN WE'RE IN THE WOMB.

ONCE YOU'RE BORN, A FEW SNUGGLES
FROM YOUR MUM OR DAD

AND YOU'VE PROBABLY GOT MITES.

♪♪

WHILE THIS IS BOTH FASCINATING
AND DISTURBING,

IT JUST GOES TO SHOW THAT
OUR SKIN ISN'T JUST AN ORGAN.

IT'S AN ENTIRE ECOSYSTEM.

THIS DISCOVERY HAS OPENED UP

A WHOLE NEW LINE
OF SCIENTIFIC INQUIRY.

BY TESTING MITE DNA
FROM AROUND THE GLOBE,

SCIENTISTS REVEALED IN 2015
THAT DIFFERENT HUMAN POPULATIONS

HAVE DIFFERENT MITE POPULATIONS,

HANDED DOWN
THROUGH THE GENERATIONS.

THIS MEANS WE CAN MAP
WHICH CONTINENT

A PERSON'S ANCESTORS CAME FROM

BY STUDYING THE MITES
ON THEIR SKIN.

WE MAY EVEN BE ABLE TO TRACE
ANCIENT HUMAN-MIGRATION PATTERNS

BY STUDYING MITE DNA,

SHEDDING NEW LIGHT
ON OUR EVOLUTION.

AND THE EXTRAORDINARY STORY
DOESN'T END THERE.

EVERY MAMMAL SPECIES
TESTED SO FAR

HAS ITS OWN
FAMILIAL DEMODEX MITES --

PROOF THAT SKIN
STILL HAS ITS SECRETS.

♪♪

WHEN IT COMES
TO HELPING VERTEBRATES THRIVE

IN AN UNPREDICTABLE WORLD,

SKIN, WHICH IS BOTH RESOURCEFUL
AND ADAPTABLE,

IS THE ULTIMATE
MULTIPURPOSE TOOL,

HELPING ANIMALS
DEFEND THEMSELVES,

DISGUISE THEMSELVES,
EVEN COMMUNICATE.

AND IT'S STILL
FULL OF SURPRISES.

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

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS