All language subtitles for 4 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 THE CASE
THAT HE'S HAIRLESS.

THE SKIN'S
TOTALLY DIFFERENT.

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

AT 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
EXTRA-SENSORY ABILITIES.

WE'RE EVEN DISCOVERING
THE COMPLEX ECOSYSTEM

LIVING ON OUR SKIN.

OH, JIM, THAT'S AWFUL.

IT REALLY IS!

IN THIS EPISODE, I'LL UNCOVER
INCREDIBLE NEW SCIENCE

ABOUT PUFFINS AND THEIR BEAKS,

WITNESS A DEADLY SNAKE
SEND ME A WARNING SIGNAL

WITHOUT EVEN OPENING ITS MOUTH,

AND LEARN TO READ
THE COLOR-CODED MESSAGES

MANDRILLS SEND TO EACH OTHER
THROUGH THEIR FACES,

TO MARVEL AT HOW SKIN
HAS EVOLVED,

ALLOWING ANIMALS TO COMMUNICATE.

I'M GOING TO REVEAL
THE SECRETS OF SKIN.

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

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS

♪♪

ANIMALS COMMUNICATE
THROUGH SMELL,

COLOR, TOUCH, AND SOUND.

[ CALLING ]

AND THEIR SKIN HAS ADAPTED
TO HELP THEM DO JUST THAT.

I'M STARTING WITH
A VERY FAMILIAR PRIMATE,

RING-TAILED LEMURS,

WHICH USE THE SMELL
OF THEIR SKIN TO FIGURE OUT

WHO'S WHO AND WHAT'S WHAT.

♪♪

WITH THEIR DISTINCT
BLACK-AND-WHITE MARKINGS

AND THOSE UNMISSABLE
STRIPY TAILS,

RING-TAILED LEMURS ARE HARD
TO TELL APART BY SIGHT ALONE.

SO THEY'VE EVOLVED
A LANGUAGE OF SMELL.

AND IT'S THE MALES
I'M REALLY INTERESTED IN.

♪♪

I LOVE THAT CLASSIC
LEMUR POSE!

[ CHUCKLES ]

SO, I'VE COME TO TWYCROSS ZOO

TO GET CLOSE TO A GROUP
OF CAPTIVE MALES.

THE ONE BEHIND YOU IS ZAC.
SO, HE'S GOT A VERY DARK FACE.

AND THEN WE HAVE GOT ONE,
SOMEWHERE.

HERE HE IS!

SO, ZEUS, HE'S GOT
HIS LITTLE CAULIFLOWER EAR.

WE'VE ALSO GOT ONE
WITH A SHORTER TAIL,

SO, THIS IS ZAZU
UP HERE.

WHILE KIRSTY, THEIR KEEPER, CAN
IDENTIFY A FEW OF THEM BY SIGHT,

LEMURS USE
A TOTALLY DIFFERENT WAY

OF RECOGNIZING ONE ANOTHER.

THEY USE SCENT.

BOTH SEXES HAVE SCENT GLANDS
IN THEIR GENITAL REGIONS,

BUT MALES HAVE GONE
ONE STEP FURTHER

AND EVOLVED SCENT GLANDS
ON THEIR SHOULDERS AND FOREARMS.

THEY'LL USE THAT
TO SCENT-MARK

ALL OF THEIR FURNITURE
IN THE ENCLOSURE.

THEY'LL ALSO DO IT A LOT
WITH THEIR SCENT-MARKING.

THEY'LL WIPE IT ALONG
THEIR TAILS.

IT'S SORT OF, LIKE,
A TERRITORIAL THING.

THE SCENT GLANDS ARE
OIL-PRODUCING SEBACEOUS GLANDS,

LIKE WE HAVE IN OUR SKIN.

BUT THEIRS HAVE EVOLVED

AND ARE UNLIKE ANYTHING ELSE
IN THE ANIMAL KINGDOM,

PRODUCING AN ENTIRE
CHEMICAL LANGUAGE.

♪♪

SCIENTISTS HAVE IDENTIFIED
OVER 200 CHEMICAL COMPOUNDS

THAT MAKE UP THE SCENT
LEMURS PRODUCE,

MEANING THAT THEY CAN ALL CREATE

A PERSONALIZED AROMA
TO COMMUNICATE.

♪♪

[ LEMURS CHATTERING ]

THE NUMBER OF COMPOUNDS
IN THE SCENT DROPS BY 10%

IF A LEMUR IS INJURED,

SOMETHING OTHER MALES
CAN USE TO THEIR ADVANTAGE

BY ACTING MORE AGGRESSIVELY
TO THE WEAKER MALE.

♪♪

MALE RING-TAILED LEMURS
ALSO USE THEIR SMELL TO FIGHT.

THEY RUB THEIR TAILS
IN THEIR SCENT GLANDS,

AND THEN WAFT THE SMELL IN
THE DIRECTION OF THEIR RIVALS.

THESE BATTLES MAINTAIN
SOCIAL STATUS

WHILE REDUCING
PHYSICAL AGGRESSION.

AND THEIR SCENT
DECIDES THE WINNER.

♪♪

♪♪

ANOTHER GROUP OF PRIMATES
HAS DEVELOPED A DIFFERENT WAY

OF COMMUNICATING DOMINANCE
THROUGH THEIR SKIN --

COLOR OF THEIR RUMP AND FACE.

THESE ARE MANDRILLS IN GABON,
WEST AFRICA.

CHARLES DARWIN WROTE,

"NO OTHER MEMBER IN
THE WHOLE CLASS OF MAMMALS

IS COLORED IN SO EXTRAORDINARY
A MANNER

AS THE ADULT MALE MANDRILL."

PRIMATOLOGIST JO SETCHELL
HAS BEEN STUDYING

AND PHOTOGRAPHING THESE
MANDRILLS FOR OVER 20 YEARS.

♪♪

JO, I LOVE THESE ANIMALS,

ONE OF THE MOST RECOGNIZABLE
MEMBERS OF OUR PRIMATE FAMILY.

-AREN'T THEY FABULOUS?
-THEY REALLY ARE.

THEY HAVE THESE REMARKABLE
RED AND BLUE NOSES.

AND THEY'RE USING THIS RED
AND BLUE SKIN

TO COMMUNICATE
WITH ONE ANOTHER.

WHAT ARE THEY COMMUNICATING?

STATUS, ESSENTIALLY.

SO, IF THEY CAN LOOK AT
THE RED COLOR OF ANOTHER MALE,

DECIDE INSTANTLY
WHETHER HE'S DOMINANT,

AND THEREFORE,
YOU SHOULD AVOID HIM,

OR HE'S SUBORDINATE.

THEN THAT AVOIDS FIGHTS.

SO, IT PAYS OFF TO SIGNAL

RATHER THAN TO FIGHT
IT OUT, I GUESS?

DEFINITELY, YES.

DO WE KNOW WHAT'S GOING
ON BENEATH THE SKIN?

RIGHT BENEATH THAT RED SKIN
IS BLOOD,

AND THERE'S AN AWFUL LOT OF
BLOOD VESSELS, VASCULARIZATION.

AND SO THE RED OF THE BLOOD
IS SEEN RIGHT THROUGH THE SKIN.

UNLIKE HUMANS, WHOSE SKIN COLOR
COMES FROM MELANIN,

THAT INTENSE RED
OF A MALE MANDRILL'S FACE

OWES ITSELF TO OXYGENATED
HEMOGLOBIN

IN BLOOD VESSELS
CLOSE TO THE SKIN'S SURFACE.

♪♪

THE BLUE COLOR IS FORMED
BY THE STRUCTURE OF COLLAGEN

WITHIN THE DERMIS.

AND IT'S ALIGNED IN A WAY
THAT SCATTERS THE VISIBLE LIGHT,

WHICH WE SEE AS BLUE.

SO, HERE WE HAVE
ANOTHER ADULT MALE,

AND THE FIRST ONE
WAS ALSO AN ADULT MALE,

AND THEIR RED SKIN
IS EXTREMELY SIMILAR.

WHAT THAT SKIN IS SAYING

IS THAT THEY ARE
OF VERY SIMILAR DOMINANCE.

WHEN THERE ARE TWO
THAT ARE SO SIMILAR,

THERE MUST BE ISSUES
WITH THAT?

YES. SO, THESE ARE
THE SORTS OF MALES

THAT WILL FIGHT
WITH ONE ANOTHER,

PRESUMABLY BECAUSE THEY CAN'T
TELL EASILY FROM THE RED SKIN

WHO IS DOMINANT OVER WHOM.

♪♪

COLOR COMMUNICATION
FOR MALE MANDRILLS

CAN BE A LIFE-SAVING STRATEGY.

THOSE CANINES ARE AMONG
THE LARGEST OF ANY PRIMATE,

REACHING UP TO 5 CENTIMETERS
IN LENGTH.

THEY CAN INFLICT SERIOUS INJURY,
AND EVEN DEATH.

SO FIGHTING IS A LAST RESORT.

THESE TWO MALES
OF SIMILAR COLOR AND STATUS

BOTH WANT THE RIGHT TO MATE
WITH THE FEMALES.

ONLY ONE WILL BE VICTORIOUS.

AND A SURGE OF TESTOSTERONE,

WHICH CAUSES THE BLOOD VESSELS
TO DILATE,

WILL MAKE HIS FACE EVEN REDDER
AND MORE ATTRACTIVE.

AND IF YOU'RE THE MALE
WHO REACHES THE TOP

OF THE PECKING ORDER,
YOUR FACE SAYS IT ALL.

♪♪

[ CHUCKLES ]
HE IS IMPRESSIVE!

HE MUST BE TOP DOG.

HE IS.
THIS IS AN ALPHA MALE,

THE MOST DOMINANT
IN THE GROUP,

AND HAS BEEN FOR ENOUGH TIME

FOR THE RED COLOR
TO MOVE UP INTO HIS EYES.

THESE ANIMALS LIVE IN GROUPS
OF HUNDREDS.

HOW MANY WILL REACH
THIS STATUS?

AS FAR AS WE KNOW, THERE'S
JUST ONE WHO LOOKS LIKE THIS.

ONCE YOU HIT THIS LEVEL,
WHAT HAPPENS WITH

THE INTERACTIONS BETWEEN
THE OTHER MALES,

THE ONES THAT ARE BRIGHTLY
COLORED, BUT NOT LIKE THIS?

ANY MALE THAT IS NOT THIS
BRIGHTLY COLORED WILL STAY AWAY.

PRIMATES MAY USE COLOR

AND EVEN SMELL PRODUCED
BY THE SKIN TO COMMUNICATE.

BUT WHEN IT COMES TO DARKER
ENVIRONMENTS

WITH POOR VISIBILITY,
ONE UNIQUE GROUP OF FISH

HAS EVOLVED SOME REALLY
FASCINATING WAYS

TO SEND OUT A MESSAGE
WITH THE HELP OF THEIR SKIN.

THIS IS A BLACK GHOST KNIFEFISH.

AT FIRST GLANCE, IT MIGHT NOT
LOOK VERY IMPRESSIVE.

IT ISN'T BRIGHTLY COLORED,
IT DOESN'T HAVE AMAZING SPINES,

OR ANYTHING LIKE THAT.

IN FACT, IT'S JUST BLACK
WITH A COUPLE OF WHITE STRIPES

AND A RATHER IMPRESSIVE-LOOKING
FRILL.

BUT THIS LITTLE
SOUTH AMERICAN FISH,

THANKS TO ITS SKIN,

IS ALMOST ABLE TO DEFY
THE LAWS OF NATURE.

BLACK GHOST KNIFEFISH HAVE
EVOLVED A HIGHLY SPECIALIZED WAY

OF COMMUNICATING --
THEY USE ELECTRICITY.

♪♪

THERE ARE MORE THAN 30,000
SPECIES OF FISH ON THE PLANET,

BUT ONLY AROUND 350 CAN PRODUCE
THEIR OWN ELECTRIC FIELD.

STRONGLY ELECTRIC FISH,

LIKE ELECTRIC EELS
AND SOME RAYS,

PRODUCE AN ELECTRIC DISCHARGE
OF UP TO 800 VOLTS,

STRONG ENOUGH TO STUN
THEIR PREY.

WHILE WEAKLY ELECTRIC FISH,
LIKE THE BLACK GHOST KNIFEFISH,

PRODUCE LESS THAN ONE VOLT,

AND USE THIS TO NAVIGATE
AND COMMUNICATE.

TO SHOW ME JUST HOW THEY USE
THEIR SKIN TO DO THIS,

PhD STUDENT SARAH SKEELS
HAS SET UP AN EXPERIMENT.

♪♪

IN THE TANK,
THERE IS A SINGLE FISH,

AND A PAIR OF ELECTRODES TO
PICK UP ITS ELECTRICAL SIGNAL.

THESE ARE CONNECTED
TO A SPECIAL AMPLIFIER

WHICH CONVERTS
ELECTRIC SIGNALS INTO SOUND.

♪♪

[ SOFT BUZZING ]

DOESN'T SOUND MUCH, BUT THAT'S
THE AUDITORY REPRESENTATION

OF THE FIELD THIS LITTLE FISH
IS MAKING?

EXACTLY. SO, THEY PRODUCE
A CONTINUOUS SINE WAVE,

AND THAT'S WHAT WE'RE HEARING,
THOSE TONAL CHANGES.

AND IT MAY BE QUITE SUBTLE,

BUT IT ALLOWS THEM
TO GET MORE INFORMATION

FROM WHAT'S
IN THEIR ENVIRONMENT.

EVERY TIME HE MOVES AWAY
FROM HIS LITTLE BRANCH,

IT CHANGES SLIGHTLY.

AND EVERY TIME HE COMES BACK,
AGAIN THE TONE CHANGES.

[ SOFT BUZZING INTENSIFIES ]

BLACK GHOST KNIFEFISH HAVE
AN ELECTRIC ORGAN

RUNNING DOWN THE LENGTH
OF THEIR BODY,

WHICH IS MADE UP
OF MODIFIED MUSCLE CELLS.

EACH OF THESE CELLS DISCHARGES
A SMALL AMOUNT OF VOLTAGE,

PRODUCING THE CONSTANT ELECTRIC
FIELD AROUND THEIR BODY.

♪♪

BUT IT'S THE RECEPTOR CELLS
IN THE SKIN

THAT ACTUALLY RECEIVE
THIS ELECTRIC CHARGE,

ALLOWING THE FISH TO SENSE THEIR
SURROUNDINGS AND COMMUNICATE.

AND IS THAT WHY WE'RE SEEING
THIS REALLY WEIRD ANATOMY?

THEY'RE TYPICALLY CALLED
SCALELESS FISH,

BUT THEY ACTUALLY
HAVE VERY TINY SCALES.

AND THIS IS
AN IMPORTANT THING,

BECAUSE IF THEY HAD
LOTS OF BIG SCALES,

THEY WOULD JUST INTERFERE
AND THE SIGNAL WOULDN'T BE ABLE

TO GO VERY FAR.

IT'S THE COMMUNICATION
BETWEEN TWO FISH

THAT I'M REALLY INTERESTED IN.

THEY HAVE VERY POOR VISION,
SO IT'S THEIR ELECTRIC FIELDS

WHICH ALLOW THEM
TO SENSE ONE ANOTHER.

[ BUZZING CONTINUES ]

SO, THE MOMENT YOU PUT
THE SECOND FISH IN...

[ SOFT BUZZING INTENSIFIES ]

...YOU CAN HEAR
THERE'S SOMETHING DIFFERENT

WITH THAT TONE.

YEAH.
SO, IT'S A COMBINATION OF BOTH

OF THEIR SIGNALS
THAT WE CAN NOW HEAR.

AND IT'S REALLY INTERESTING
THAT EVERY TIME THEY GET CLOSER

TO ONE ANOTHER, EVERY TIME
THEY'RE NEAR ONE ANOTHER,

YOU GET THIS DIFFERENCE IN
THE SOUND BEING GENERATED HERE.

AS WELL AS INTERPRETING
THE ELECTRIC SIGNALS

AS AUDIBLE SOUND,
SARAH HAS AN OSCILLOSCOPE,

WHICH DISPLAYS A GRAPH
OF THE ELECTRIC VOLTAGE

BEING PRODUCED BY THE FISH.

SO, YOU CAN SEE ON THE TOP LEFT,
THIS TRACE IS FROM ONE FISH.

AND THE BOTTOM TRACE
IS FROM TWO FISH.

SO, YOU CAN SEE
ON THE TOP ONE,

WHEN THERE'S ONLY ONE FISH,
IT'S QUITE REGULAR.

BUT IF YOU SEE ON THE BOTTOM,

THERE'S A LOT OF DISTORTION
IN HERE AND HERE,

WHERE THE SIGNALS
FROM BOTH FISH ARE COMBINING

AND CREATING
SOME KIND OF INTERFERENCE.

SO, ARE THEY TRYING TO
OUTDO ONE ANOTHER?

ARE THEY TRYING TO TALK
TO ONE ANOTHER?

WHAT'S GOING ON?

SO, ELECTRIC COMMUNICATION CAN
BE USED FOR A NUMBER OF ROLES.

SO, HERE, WE THINK WE HAVE
A MALE AND FEMALE,

AND IT COULD BE USED
TO ELICIT COURTSHIP DISPLAYS.

BUT IT CAN ALSO BE USED
TO DECIDE ON TERRITORY,

WHO HAS, IN THIS EXAMPLE,
THE PIECES OF WOOD.

IT'S NOT JUST TWO FISH,
EFFECTIVELY,

TRYING TO OUTSHOUT
ONE ANOTHER.

THERE'S SOMETHING MORE GOING ON
HERE, ISN'T THERE?

THEY CAN PRODUCE SOMETHING
CALLED THE JAMMING RESPONSE,

WHERE THEY WILL CHANGE
THEIR FREQUENCY

SO BOTH OF THEM CAN SIGNAL
WITHOUT INTERRUPTING THE OTHER.

THIS JAMMING RESPONSE
ONLY OCCURS

WHEN FISH OF THE SAME SPECIES,

WITH SIMILAR ELECTRIC
FREQUENCIES, GET TOO CLOSE.

THEY CHANGE THEIR SIGNAL

SO THEY CAN BOTH STILL
COMMUNICATE

AND NAVIGATE THEIR SURROUNDINGS.

SO, IT'S THEIR WAY OF FINDING
A METHOD FOR BOTH

BEING ABLE TO BE NEAR ONE
ANOTHER WITHOUT LOSING

THIS ABILITY TO SENSE
THEIR WORLD AROUND THEM,

WHILE STILL COMMUNICATING
AT THE SAME TIME?

-EXACTLY.
-IT'S VERY COMPLEX, ISN'T IT?

YEAH, AND THE ELECTRORECEPTORS
ARE ABSOLUTELY KEY ON THE SKIN.

WITHOUT THEM,
THEY WOULDN'T BE ABLE

TO DO THIS KIND
OF BEHAVIOR.

♪♪

USING THE SKIN TO COMMUNICATE
VIA ELECTRIC SIGNALS

IS VERY SUBTLE.

BUT FOR MUCH MORE OBVIOUS
COMMUNICATION,

MANY ANIMALS HAVE EVOLVED
TO USE COLOR.

♪♪

FROM CHAMELEONS, WHO CAN CHANGE
THE COLOR OF THEIR SKIN

TO SHOW THEIR MOOD...

TO SARCASTIC FRINGEHEADS,

WHOSE GAPING, VIBRANT MOUTHS
ACT AS A WARNING SIGNAL

TO HELP DEFEND THEIR TERRITORY
FROM RIVALS.

♪♪

BUT NOWHERE IS IT MORE READILY
SEEN THAN IN BIRDS.

♪♪

THERE ARE OVER
10,000 SPECIES OF BIRD,

AND THEIR FEATHERS REPRESENT
A HUGE RANGE

IN THE COLOR SPECTRUM.

♪♪

FEATHERS ARE MADE FROM KERATIN,

A PROTEIN FORMED IN TINY
FOLLICLES IN THE EPIDERMIS.

LIKE IN REPTILES,
MAMMALS, AND FISH,

BIRDS CAN BE DIFFERENT COLORS

BECAUSE OF THE PIGMENTS
CONTAINED IN THEIR SKIN

AND THE WAY IN WHICH
THE KERATIN IS STRUCTURED.

THE MOST WIDESPREAD
COLOR-PRODUCING PIGMENT

FOUND IN NATURE IS MELANIN,

AND IT CREATES
THE DARKEST COLORS --

BLACKS, BROWNS, AND GRAYS.

♪♪

MELANIN IS PRODUCED
BY MELANOCYTES,

SPECIALIZED SKIN CELLS
LOCATED IN THE EPIDERMIS.

AND IT CAN BE SEEN IN ACTION
IN THIS GOLDEN PLOVER FEATHER.

[ CHIRPING ]

THESE SPOTS AND STRIPES
ARE PERFECT ADAPTATIONS

FOR ALLOWING THE BIRD TO ALMOST
DISAPPEAR IN ITS SURROUNDINGS.

IT'S A GREAT EXAMPLE
OF FEATHERY CAMOUFLAGE.

AND IN TERMS OF WHAT IT'S SAYING
TO THE WORLD AROUND IT,

WELL, IT'S PRETTY MUCH,
"THERE'S NOTHING TO SEE HERE."

ANOTHER TYPE OF PIGMENT

FOUND ACROSS THE ANIMAL KINGDOM
ARE CAROTENOIDS.

MOST OF THE REDS, ORANGES,
AND YELLOWS

SEEN IN BIRD FEATHERS

ARE COLORED BY THESE
CHEMICAL COMPOUNDS.

BUT, UNLIKE MELANIN, THEY ARE
NOT PRODUCED BY THE SKIN,

BUT OBTAINED FROM THE FOOD
THE BIRDS EAT.

♪♪

CAROTENOID PIGMENTS ARE THEN

TRANSPORTED THROUGH THE SKIN
TO THEIR FEATHERS.

ONCE IN PLACE, THEY ABSORB
MOSTLY BLUE LIGHT

TO PRODUCE THE ORANGE,
RED AND YELLOW COLORS

THAT WE SEE IN THESE FEATHERS.

YOU CAN SEE THE CAROTENOIDS
HAVE CLEARLY COLORED

THESE LITTLE GOLDCREST
FEATHERS A FIERY ORANGE.

AND THIS ONE IS DEFINITELY
NOT TRYING TO BLEND IN

WITH ITS SURROUNDINGS.

IT'S FROM THE CAP OF A MALE,
AND DURING THE BREEDING SEASON,

THESE LITTLE CAPS FLASH ORANGE,
YELLOWS AND GOLDS.

AND THEY'RE TRYING TO SAY,

"STAY AWAY.
THIS IS MY TERRITORY."

AS FOR THE IRIDESCENT COLORS
FOUND IN BIRDS,

THEY'RE NOT CAUSED
BY PIGMENTS IN THEIR SKIN,

BUT BY THE STRUCTURE
OF THE FEATHER ITSELF.

KERATIN WITHIN THE FEATHER
IS ALIGNED IN SUCH A WAY

THAT IT ALLOWS LIGHT TO TWIST,
TURN, AND SEPARATE

INTO A RAINBOW OF COLORS.

THIS FEATHER IS FROM
A MALE PEACOCK.

HE'S TRYING TO SAY HIS GENES
ARE AMAZING.

HE CAN WASTE ENERGY
IN THESE BIG, BRIGHT,

OSTENTATIOUS FEATHERS
BECAUSE HIS GENES ARE THAT GOOD.

BASICALLY, HE'S TELLING
EVERY OTHER FEMALE IN THE AREA,

"YOU SHOULD MATE WITH ME."

FROM UNDERSTANDING HOW FEATHERS
ARE COLORED IN MODERN-DAY BIRDS,

A WHOLE NEW APPRECIATION
OF COLORATION IN EXTINCT SPECIES

HAS BEEN POSSIBLE.

ADVANCES IN RESEARCH
OVER THE LAST TEN YEARS OR SO

HAVE TRANSFORMED
OUR KNOWLEDGE OF DINOSAURS,

ALLOWING A DEEPER FOCUS
ON FOSSILIZED FEATHERS,

AND A GREATER UNDERSTANDING
OF HOW COLOR IS PRODUCED

RIGHT ACROSS THE ANIMAL KINGDOM
IS MAKING THIS POSSIBLE.

PALEONTOLOGIST
PROFESSOR MIKE BENTON

IS SHOWING ME
A FOSSILIZED FEATHER

UNDER A SCANNING
ELECTRON MICROSCOPE.

HE AND HIS TEAM MADE
A BREAKTHROUGH

WHEN IT WAS DISCOVERED
THAT THE SHAPES EMBEDDED

IN THE FOSSILS WERE MELANOSOMES.

MELANOSOMES ARE MADE
IN MELANOCYTES,

WHICH ARE THE MELANIN-FORMING
CELLS FOUND IN THE SKIN.

THEY'RE THE SITE OF SYNTHESIS,

STORAGE, AND TRANSPORT
OF MELANIN PIGMENTS,

AND PROVIDE TISSUES WITH COLOR.

IN SOME OF THE FOSSILS,
WE FOUND THESE

KIND OF SAUSAGE-SHAPED ONES.

IN OTHERS, WE FIND SPHERICAL
ONES OR BALL-SHAPED ONES.

AND LOOKING AT EVIDENCE FROM
MODERN BIRDS AND MODERN MAMMALS,

WE DISCOVER THERE'S
AN EXACT CORRELATION

BETWEEN THE SHAPES
OF THE MELANOSOMES

AND THE COLORS THAT THEY HAVE.

EVERY TIME WE LOOKED AT A HAIR
OR A FEATHER

FROM A MODERN CREATURE
WHERE WE KNOW THE COLOR,

WE FOUND
THE SAUSAGE-SHAPED MELANOSOMES.

YOU EITHER GET BLACK IF THEY'RE
VERY TIGHTLY PACKED,

BROWN IF THEY'RE MORE LOOSELY
PACKED,

GRAY, ALL THE WAY THROUGH
TO BLOND,

WHERE THERE'S NOT
VERY MANY AT ALL.

AND WHEN WE LOOKED IN
MODERN FEATHERS AND HAIRS,

SAY, FROM
A GINGER-HAIRED PERSON,

WE FOUND THE OTHER KIND
OF MELANIN,

WHICH IS CHEMICALLY DIFFERENT,
AND IT GIVES ONLY GINGER COLORS.

AND THAT CORRESPONDS TO THIS
KIND OF BALL-SHAPED MELANOSOMES.

DOES THAT MEAN WE'RE SEEING
BROWNS AND GRAYS AND WHITES

AND EVEN GINGERS
IN SOME OF OUR DINOSAURS?

YES, AND I THINK THIS HAS
COMPLETELY REVOLUTIONIZED

THE WAY WE SEE DINOSAURS.

Garrod: DINOSAURS WERE CLEARLY
MORE COLORFUL

THAN SCIENTISTS ONCE THOUGHT,

AND IT'S NOT JUST BLACKS,
BROWNS, AND EVEN GINGERS.

FOSSILIZED REMAINS INDICATE
THAT DINOSAURS

HAD MUCH THE SAME RANGE
THAT WE SEE IN BIRDS TODAY.

THE FACT THAT YOU GET
THE SAME RELATIONSHIP

BETWEEN COLOR
AND MELANOSOME SHAPE

IN ALL THE BIRDS THAT PEOPLE
HAVE LOOKED AT

AND IN ALL THE MAMMALS
MEANS THAT, PROBABLY,

THIS IS A GENERAL RULE
OF NATURE.

Garrod: AND COLOR IS ONLY
HALF THE STORY.

FROM THE FOSSIL EVIDENCE,
MIKE AND HIS TEAM

HAVE DISCOVERED PATTERNS,
AS WELL.

THEY'VE BEEN ABLE TO PIECE
TOGETHER TRACES

OF DIFFERENT SHAPED MELANOSOMES,
AND CREATE A MORE ACCURATE IMAGE

OF WHAT A DINOSAUR
WOULD HAVE LOOKED LIKE.

THIS IS SINOSAUROPTERYX.

WE WERE SAMPLING
ACROSS THE BODY,

ALONG THE TAIL,
AND ACROSS THE HEAD, AND SO ON,

AND WE WERE ABLE TO SHOW
VERY DEFINITELY

THAT IT HAS THESE GINGER
AND WHITE STRIPES.

SO, THE FIRST THING
WAS WE ONLY FOUND

THE BALL-SHAPED MELANOSOMES,
THEREFORE, ALL GINGER.

WE COULDN'T FIND ANY HINT

OF THE SAUSAGE SHAPES
OR BLACK OR BROWN COLORS.

AND IN THE AREAS SHOWING WHITE,
WE WERE FINDING NO MELANOSOMES.

WHAT WAS SINOSAUROPTERYX DOING?
WHAT WAS HIS COLORATION FOR?

AT FIRST, WE SAW THE STRIPES,
AND WE THOUGHT,

"WELL, COULD IT BE
CAMOUFLAGE?"

I MEAN, THAT'S A BIG FUNCTION
OF COLOR, OF COURSE.

WE THINK OF TIGERS AND ZEBRAS
AND SO ON.

BUT THE FACT IS THE STRIPES

DON'T OCCUR
ACROSS THE WHOLE BODY,

SO IT'S NOT LIKELY YOU WOULD
SIMPLY CAMOUFLAGE YOUR TAIL.

AND SO THE OTHER FUNCTION

THAT SEEMED QUITE OBVIOUS
WOULD BE DISPLAY.

AND, OF COURSE, A TAIL
IS A PERFECT DISPLAY ORGAN.

AND, PRESUMABLY, WHOEVER HAD
THE BRIGHTEST, LONGEST,

STRIPIEST TAIL PROBABLY
WOULD WIN THE MOST MATES.

Garrod: COLOR IS ONE WAY
TO COMMUNICATE USING YOUR SKIN.

BUT FOR MORE AGGRESSIVE SIGNALS,

SKIN HAS EVOLVED
TO PRODUCE ITS OWN SOUND.

♪♪

[ HISSING ]

THIS IS A DESERT HORNED VIPER.

I LOVE THIS LITTLE SNAKE.
ABSOLUTELY INCREDIBLE.

BUT I'M NOT GONNA GET ANY
CLOSER BECAUSE IT'S VENOMOUS.

AND, ACTUALLY, MORE THAN THAT,

THIS LITTLE SNAKE IS DEADLY.

AND WHAT I REALLY LOVE
ABOUT THIS SNAKE...

[ HISSING ]

...IS THAT NOISE.

[ HISSING ]

RIGHT NOW, I'M BEING TOLD,

IN NO UNCERTAIN TERMS,
"STAY AWAY."

"GET BACK...OR ELSE."

[ HISSING ]

♪♪

DESERT HORNED VIPERS LIVE
IN THE SAHARA, IN NORTH AFRICA.

THEY'RE SIDEWINDERS
AND ARE THE MOST ABUNDANT

AND VENOMOUS SNAKES
IN THIS REGION.

LIKE ALL DESERT VIPERS,

THEY'VE EVOLVED TO COMMUNICATE
THROUGH THEIR SKIN,

TELLING ANYONE WHO CAN HEAR THEM
THAT THEY ARE DANGEROUS.

TO DO THIS,
THEY HAVE KEELED SCALES,

WHICH THEY USE TO PRODUCE
A HISSING SOUND OF THEIR OWN.

[ HISSING ]

HE'S ARRANGING HIS BODY

INTO A SERIES OF
PARALLEL "S"-SHAPED CURVES.

AND ONCE HE'S DONE THAT, HE'S
RUBBING THESE LATERAL SCALES,

THE ONES DOWN THE SIDE OF
HIS BODY, AGAINST ONE ANOTHER,

AND THAT IS HOW
HE'S MAKING THIS NOISE.

[ HISSING ]

KEELED SCALES,
UNLIKE THE SMOOTH VARIETY

FOUND IN MOST OTHER SNAKES,

HAVE A RIDGE RUNNING DOWN
THE CENTER LINE.

THIS GIVES THE ADDED ADVANTAGE

OF REDUCING THE SHINE
OF THE SNAKE'S SKIN,

HELPING WITH CAMOUFLAGE AND
KEEPING IT OUT OF HARM'S WAY.

IT'S A GREAT NATURAL DETERRENT.

IN THE WILD, PREDATORS KNOW
TO KEEP THEIR DISTANCE,

AND THIS ALLOWS THE SNAKE
TO KEEP ITS PRECIOUS VENOM

IT CAN USE TO CATCH ITS PREY.

[ HISSING ]

♪♪

SOUND CAN BE AN EFFECTIVE WAY
TO CONVEY A WARNING,

BUT SOME NOISES IN THE ANIMAL
KINGDOM AREN'T CREATED BY SKIN.

[ INDISTINCT CONVERSATIONS ]

MANY ANIMALS HAVE A VOICE BOX
WHICH, LIKE IN HUMANS,

IS OFTEN USED TO PRODUCE
A WIDE ARRAY OF SOUNDS.

THE FURTHEST A HUMAN CAN PROJECT
THEIR VOICE IS ABOUT 180 METERS.

BUT ONE PRIMATE USES
ITS SPECIALLY ADAPTED SKIN

TO THROW ITS VOICE MORE
THAN 10 TIMES THAT DISTANCE.

[ GIBBONS CALLING ]

AND I'VE COME TO TWYCROSS ZOO
TO TAKE A CLOSER LOOK.

♪♪

THESE BEAUTIFUL ANIMALS
ARE SIAMANGS.

THEY'RE THE LARGEST
OF THE GIBBONS

AND ACTUALLY ONE OF THE
LOUDEST ANIMALS ON THE PLANET.

THEY'RE NOT MAKING A HUGE AMOUNT
OF NOISE RIGHT NOW

BECAUSE THEY'RE HAVING
THEIR BREAKFAST,

BUT WHEN THEY CALL,

YOU CAN HEAR THEM
FROM OVER 2 KILOMETERS AWAY.

AND, IF I WAS TO STAND
NEXT TO THEM,

THEY'D BE LOUDER
THAN A ROCK CONCERT.

[ SIAMANGS CALLING ]

IN THEIR FOREST HOMES
OF SOUTHEAST ASIA,

VISUAL GESTURES WOULD BE LOST
IN THE DARK CANOPY OF THE TREES,

SO LOUD VOCALIZATIONS
PLAY AN IMPORTANT ROLE

TO FEND OFF
NEIGHBORING SIAMANGS.

[ SIAMANGS CALLING ]

AND THEY CAN ONLY DO ALL THIS
BECAUSE OF THEIR SKIN.

THEY'VE GOT THESE INCREDIBLE,
LARGE INFLATABLE THROAT SACS

THAT REALLY HELPS THROW
THEIR VOICE AS FAR AS POSSIBLE.

IT'S THE ELASTIN AND COLLAGEN
WITHIN THE SKIN

THAT ALLOWS THE SIAMANGS
TO INFLATE THEIR THROAT SACS

TO THE SIZE OF THEIR HEADS.

BUT THIS SKIN DOESN'T GET IN THE
WAY WHEN THEY'RE NOTCALLING.

THANKS TO ITS PHYSICAL
PROPERTIES,

THE SKIN IS ABLE TO SPRING BACK
TO NORMAL WHEN NOT IN USE.

♪♪

THE ANIMAL KINGDOM HAS EVOLVED

SO MANY AMAZING WAYS
TO COMMUNICATE

THAT WE ARE ONLY STILL
JUST SCRATCHING THE SURFACE.

BUT BRAND-NEW SCIENCE
HAS CHANGED OUR UNDERSTANDING

OF HOW ONE LITTLE BIRD
COMMUNICATES USING ITS SKIN.

THE PUFFIN.

JAMIE DUNNING
IS AN ORNITHOLOGIST

AND HAS BEEN WORKING WITH BIRDS
FOR OVER 10 YEARS.

JAMIE, THESE ARE
SUCH AMAZING BIRDS.

THEY'RE INSTANTLY
RECOGNIZABLE.

AND THEY'RE ONE OF OUR
MOST ICONIC SEASIDE SPECIES.

AND IT'S ALL DOWN
TO THIS BEAUTIFUL,

VIBRANTLY COLORED BEAK.

BUT THERE'S SO MUCH GOING ON
BEHIND THE SCENES HERE,

ISN'T THERE?
YEAH.

SO, THE BEAK IS ALMOST CERTAINLY
A BIG KIND OF ORNAMENT,

A FLAG TO SUGGEST FITNESS
AND SEXUAL SELECTION

AND HELP THEM CHOOSE MATES.

'CAUSE BOTH MALES
AND THE FEMALES

HAVE THIS BEAUTIFUL BILL.

AS WITH ALL BIRDS,
THE PUFFINS' BEAKS ARE COVERED

IN THE COMPLEX PROTEIN KERATIN,

WHICH FORMS A HARD OUTER LAYER.

CAROTENOIDS
HAVE BECOME CONCENTRATED

IN THE KERATIN COVERING
TO GIVE THESE VIBRANT COLORS.

♪♪

IT MUST BE QUITE DIFFICULT

IN TERMS OF THE ENERGY
EXPENDITURE, THEN,

TO INVEST IN A BILL LIKE THIS
YEAR-ROUND?

THIS IS ONLY
HALF THE STORY.

SO, YOU ONLY NEED THIS
IN THE SUMMER.

IT LOOKS VERY DIFFERENT
OVER WINTER.

WELL, THIS IS
COMPLETELY DIFFERENT.

IT'S LIKE A WHOLE DIFFERENT
SPECIES OF BIRD.

THOSE BRIGHT COLORS
ARE GONE.

THE MAJORITY OF THAT
BIG, COLORFUL BILL

JUST FLAKES OFF OVER WINTER.
THERE'S NO NEED FOR IT.

SO WE ONLY SEE THOSE
BRIGHTLY COLORED BILLS

IN SUMMER AND SPRING,
THEIR BREEDING MONTHS?

WE DO, AND THAT COINCIDES
WITH WHEN WE SEE PUFFINS,

'CAUSE THEY ONLY COME TO LAND
DURING THE BREEDING SEASON.

THE WINTER IS SPENT OUT
IN THE MIDDLE OF THE SEA.

JAMIE HAS MADE
A GROUND-BREAKING DISCOVERY

ABOUT THE SKIN
ON A PUFFIN'S BEAK.

TO SHOW ME,

HE'S BROUGHT A PUFFIN ALONG
WHICH DIED NATURALLY

AND IS NOW PART OF HIS STUDY.

♪♪

JAMIE, THIS IS AMAZING!
IT'S SO COOL!

I MEAN...
IT'S GLOWING.

SO, THIS IS FLUORESCENCE.

THIS IS THE SEASONALLY
DEVELOPED BILL.

SO, THIS BIT ALL DROPS OFF,
INCLUDING THE FLUORESCENT BIT.

IT'S VISIBLE WITH THIS
U.V. LAMP AND TORCH,

BUT A LOT OF BIRDS CAN SEE
U.V. COLOR, CAN'T THEY?

YEAH, THAT'S RIGHT.

SO, WE HAVE THREE TYPES OF
COLOR RECEPTOR IN OUR EYE,

OR CONE CELLS.
THAT'S RED, GREEN AND BLUE.

AND WE MIX THOSE TO MAKE
ALL THE COLORS THAT WE CAN SEE.

BIRDS HAVE A FOURTH.
THEY HAVE TETRACHROMATIC VISION.

AND THAT FOURTH ONE
ALLOWS THEM TO SEE,

TO SOME DEGREE,
IN U.V. LIGHT.

FOR BIRDS, BEING ABLE TO SEE
U.V. LIGHT HAS ITS BENEFITS.

IT ENABLES A METHOD
OF COMMUNICATION

WHICH IS INVISIBLE
TO POTENTIAL PREDATORS

BUT ALLOWS THEM TO FIND A MATE.

AS THIS IS THE BIT
THAT FALLS OFF

OUTSIDE OF
THE BREEDING SEASON,

THERE'S A VERY GOOD CHANCE
THAT THIS HAS SOMETHING TO DO

WITH SEXUAL SIGNALING
AND FITNESS

AND LURING IN
THE OPPOSITE SEX.

IT'S AMAZING.

THESE LITTLE BIRDS THAT WE KIND
OF GROW UP KNOWING SO WELL

ACTUALLY HAVE A LOAD
OF SECRETS IN THEIR SKIN

THAT WE DIDN'T KNOW BEFORE.

IT'S EXCITING.

UNTIL RECENTLY, WE HAD
NO IDEA ABOUT THIS.

♪♪

Garrod: SKIN HAS ALLOWED ANIMALS
TO COMMUNICATE.

FROM VIBRANT COLORS...

TO SOUND...

TO ELECTRICAL SENSING...

THE SKIN DOES IT ALL.

♪♪

♪♪

♪♪

♪♪