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 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.

♪♪

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