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I WAS TAKEN OUT TO THIS SITE
IN THE MIDDLE OF THE DESERT.
Official YIFY movies site: YTS.MX
I HAD NO IDEA WHAT AWAITED ME.
AND THEN I SAW THEM AND I JUST STARTED CRYING.
THESE TRACKWAYS IN THE ARABIAN DESERT
ARE FOOTPRINTS IN TIME.
THEY WERE MADE SEVEN MILLION YEARS AGO
BY PREHISTORIC ELEPHANTS.
THEY TAKE US BACK TO A BYGONE WORLD
AND ITS VANISHED CREATURES.
HOW DID ELEPHANTS FROM SO LONG AGO GIVE RISE
TO THE MAGNIFICENT ANIMALS WE KNOW TODAY?
HOW DID ANY OF THE ANIMALS IN THIS AFRICAN LANDSCAPE
BECOME WHAT THEY ARE?
FOR GENERATIONS, IT WAS A MYSTERY.
NOW SCIENTISTS ARE REVEALING THE ANSWERS,
PIECING TOGETHER AN EPIC STORY.
THIS FILM UNLOCKS THE EVOLUTION
OF FOUR OF THE WORLD'S MOST SPECTACULAR CREATURES,
CROCODILES, BIRDS,
WHALES, AND ELEPHANTS.
LIKE EVERY ANIMAL ALIVE TODAY,
THEY HAVE A DEEP TIME HISTORY,
A LINEAGE FULL OF TWISTS AND TURNS,
SHAPED BY STRANGE ANCESTORS FROM LONG AGO.
BIZARRE ANCIENT CROCS-- THIS THING WAS BUILT
LIKE A GREYHOUND. FEATHERED DINOSAURS--
DINOSAURS NEVER WENT EXTINCT.
IN FACT, BIRDS ARE DINOSAURS.
A WHALE ANCESTOR THAT LIVED ON LAND--
IT MORE LOOKS LIKE A DOG WITH A LONG SNOUT.
IT'S A STORY MILLIONS OF YEARS IN THE MAKING,
OF LOST CREATURES REDISCOVERED,
AND THE SURPRISING LESSONS OF DEEP TIME.
MADAGASCAR.
250 MILES OFF THE COAST OF AFRICA.
THIS ISLAND IS A PERFECT LABORATORY
FOR THE STUDY OF EVOLUTIONARY CHANGE.
ISOLATED HERE FOR MILLIONS OF YEARS,
SPECIES HAVE TRANSFORMED IN UNIQUE WAYS.
SCIENTISTS HAVE LONG STUDIED THE EVOLUTION
OF THE ISLAND'S CHAMELEONS, BATS, AND LEMURS.
NOW THE SEARCH IS ON FOR THE ANCIENT HISTORY
OF ONE OF EARTH'S STRANGEST ANIMALS--
THE CROCODILE.
IN FLOODED UNDERGROUND CAVES,
RESEARCHERS ARE LOOKING FOR THE REMAINS
OF AN EXTINCT CROC SPECIES.
IT MAY HAVE DISAPPEARED JUST 2,000 YEARS AGO,
A RECENT TWIST IN THE STORY OF CROCS.
SOME PEOPLE SEE CROCODILES AS THIS ANIMAL
THAT'S UNCHANGING THROUGH TIME.
AND, ACTUALLY, WE KNOW NOW THAT THAT'S NOT TRUE,
BUT THEY LOOK LIKE IT.
COLD-BLOODED,
FEROCIOUS,
BUT STRANGELY BEAUTIFUL.
THE 14 LIVING CROCODILE SPECIES ARE ALL VERY SIMILAR.
MOST OF THE LIVING SPECIES OF CROCODILE
ARE REALLY, REALLY HARD TO TELL APART,
UNLESS YOU'RE SOMEBODY WHO SPENDS
ALL YOUR TIME THINKING ABOUT CROCODILES LIKE ME.
THEY ALL HAVE THE SAME REPTILIAN BODY PLAN,
LOW TO THE GROUND
AND ARMORED FROM HEAD TO TOE IN THICK SCALES.
THEY SEEM LIKE LIVING FOSSILS,
SOME HANGOVER FROM THE AGE OF THE DINOSAURS.
BUT ARE THEY?
IS THIS REALLY AN ANIMAL FROZEN IN TIME?
PERHAPS THE MYSTERIOUS SPECIES IN THE CAVE
WILL PROVIDE SOME ANSWERS ABOUT RECENT CROCODILE EVOLUTION.
SO, THERE'S THIS CROCODILE THAT EXISTED
ON THE ISLAND OF MADAGASCAR UNTIL RELATIVELY RECENTLY
AND IT DISAPPEARS ABOUT THE SAME TIME
THAT HUMANS GOT HERE,
AND THAT CROCODILE WAS CALLED
THE HORNED CROCODILE OF MADAGASCAR.
AND SO, ONE OF THE BIG QUESTIONS IS WHAT WAS THAT CROCODILE?
WHO WERE ITS RELATIVES?
AND, WHAT HAPPENED TO IT?
IT'S ONE OF THE BIGGEST MYSTERIES.
TODAY, THERE IS ONLY ONE SPECIES ON MADAGASCAR,
THE FAMOUS NILE CROCODILE,
ONE OF THE FIERCEST OF AFRICA'S PREDATORS.
SCIENTISTS THINK IT SQUEEZED OUT THE SMALLER HORNED CROC,
BUT THERE'S A LOT THEY DON'T KNOW.
THERE MAY BE ANSWERS IN THE FLOODED CAVES.
I KNEW FROM SPEAKING WITH SOME OTHER PEOPLE
THAT THERE WERE SUPPOSEDLY CROCODILE SKULLS IN THIS CAVE
OF THIS SPECIES THAT NO ONE HAS SEEN FOR AT LEAST 200 YEARS,
BUT MORE LIKELY A THOUSAND YEARS.
A HALF-HOUR IN THEY SEE IT,
A SKULL.
-SO EXCITED. -A SKULL?
YEAH. LOOK AT THAT.
IT'S BEAUTIFUL. IT LOOKS PERFECT.
THIS IS A SKULL OF THE EXTINCT
HORNED CROCODILE OF MADAGASCAR.
AND WHEN RESEARCHERS FIRST STARTED COMING
TO MADAGASCAR FROM EUROPE,
THEY SAW THESE CROCODILE SKULLS
AND THEY WEREN'T SURE EXACTLY WHAT THEY WERE.
THEY DIDN'T LOOK EXACTLY LIKE NILE CROCODILES.
THEY REALIZED IT WAS A SEPARATE SPECIES.
IF EVON'S LUCKY,
SHE'LL BE ABLE TO EXTRACT ITS DNA
AND LEARN WHERE THE HORNED CROC FITS
INTO THE STORY OF CROCODILE EVOLUTION.
TO MEET THE VERY FIRST CROCS,
WE MUST TRACE ONE BRANCH OF THE VAST TREE OF LIFE
FAR BACK IN DEEP TIME,
230-MILLION YEARS INTO THE GEOLOGIC PERIOD
CALLED THE TRIASSIC.
IT'S HARD TO IMAGINE SUCH A VAST EXPANSE OF TIME.
IF YOU LOOK, FOR INSTANCE, AT YOUR HISTORICAL TIME,
YOU CAN THINK BACK TO YOUR GRANDPARENTS
AND THAT TIME FRAME THAT PEOPLE ARE STILL COMFORTABLE WITH.
BUT YOU GO FURTHER BACK,
GO SAY BACK THOUSANDS OF YEARS
WHEN MUCH OF NORTH AMERICA WAS COVERED BY ICE.
A VERY DIFFERENT WORLD.
BUT GO FURTHER BACK YET.
GO BACK TO A HUNDRED MILLION YEARS
AND THIS WORLD WOULD HAVE BEEN ENTIRELY UNRECOGNIZABLE.
WOULD HAVE BEEN LIKE GOING TO ANOTHER PLANET
AND SEEING LIFE FORMS THAT WERE,
FOR THE MOST PART, UTTERLY ALIEN TO OUR EXPERIENCE
AND THIS IS REALLY DIFFICULT TO GRASP.
THERE IS LITTLE ABOUT THE PLANET
OF THE TRIASSIC WE WOULD RECOGNIZE.
THE CONTINENTS WE KNOW TODAY HAD NOT YET FORMED.
THEY WERE ALL CONTAINED IN ONE HUGE LAND MASS
SURROUNDED BY WATER, PANGAEA.
IT WAS HERE, ALONG WITH THE DINOSAURS,
THAT THE FIRST CROCS EVOLVED.
IN THE BEGINNING,
THEY WERE EVEN MORE SUCCESSFUL THAN THE DINOSAURS,
AND TO OUR EYES, THEY LOOK TOTALLY BIZARRE.
WELL THE TRIASSIC WAS IN MANY WAYS,
ACTUALLY THE AGE OF CROCODILES,
AND IN ANY TRIASSIC LANDSCAPE,
YOU WOULD HAVE SEEN THIS VAST DIVERSITY
OF CROCODILE RELATIVES WITH MANY BODY FORMS.
ANJAN BHULLAR HAS BEEN UNEARTHING THE BONES
OF THE VERY FIRST CROCODILE RELATIVES.
TWO OF THEM WERE FOUND TOGETHER
NEAR SOME SANDSTONE CLIFFS IN SOUTHERN UTAH.
WELL THESE ARE TWO OF THE MOST EXTRAORDINARY SKELETONS
FROM THE CROCODILE LINE THAT HAVE EVER BEEN FOUND.
THIS LARGE ANIMAL HERE IS SOMETHING CALLED A POPOSAUR.
AND IT'S THE ONLY COMPLETE SKELETON OF ONE OF THESE ANIMALS
THAT'S EVER BEEN FOUND.
ALL OF THE SUBTLE FEATURES ON IT, I MEAN IT'S JUST,
IT'S THE FIND OF A LIFETIME.
THESE ANIMALS SHOW US WHAT CROCODILES WERE LIKE
AT THE BEGINNING OF THEIR EVOLUTION
AND THEY'RE VERY, VERY DIFFERENT.
THE EXTRAORDINARY THING ABOUT THIS ANIMAL
IS THAT IT WAS REALLY TRYING TO BE A DINOSAUR
BEFORE DINOSAURS WERE DOMINANT,
IN THAT IT WAS ACTUALLY WALKING AROUND ON TWO LEGS.
YOU SEE HOW LARGE AND HOW HEAVILY BUILT
THE LEGS OF THIS ANIMAL ARE
COMPARED TO THESE TINY LITTLE ARMS.
AND SO, THIS ANIMAL COULDN'T REST
ANY OF ITS WEIGHT ON ITS ARMS.
POPOSAURUS WAS A FIERCE,
FAST-MOVING LAND PREDATOR,
ACTING FOR ALL THE WORLD LIKE A DINOSAUR.
AND IT WASN'T THE ONLY STRANGE TRIASSIC CROC
TO BE FOUND IN UTAH.
IN FACT, THE POPOSAUR, THIS LARGE SKELETON,
WAS THE FIRST THING WE FOUND,
AND WE DUG OUT THIS BIG SKELETON.
THEN RIGHT UNDERNEATH IT WAS A TINY FOOT.
AND UNDERNEATH THAT FOOT WAS THIS ANIMAL HERE,
WHICH IS THE ONLY COMPLETE SPECIMEN
OF WHAT WE CALL A SPHENOSUCHIAN GRADE STEM CROCODILE
THAT'S EVER BEEN FOUND.
THEY CALLED THE SPHENOSUCHIAN, LITTLE FOOT.
IT WAS EVEN STRANGER THAN POPOSAURUS.
AND SO, THE POPOSAUR IS SOMETHING LIKE MOUNTAIN LION,
WHEREAS THE SPHENOSUCHIAN, YOU LOOK AT THIS ANIMAL,
AND IT'S GOT A SLENDER LITTLE BODY,
IT'S GOT EXTRAORDINARILY LONG LEGS.
EXTRAORDINARILY LONG ARMS,
AND THESE ARMS WERE TAKING ITS WEIGHT,
UNLIKE THOSE OF THE POPOSAUR.
AND SO, THIS THING WAS BUILT ALMOST LIKE A GREYHOUND
WITH A HEAVY HEAD AND A LONG TAIL.
IT WAS AN ANIMAL THAT WAS UTTERLY BUILT FOR SPEED.
THE STRANGE CREATURES OF THE TRIASSIC
WERE PART OF THE FIRST GREAT FLOWERING
OF THE CROCODILE FAMILY TREE.
BUT 200 MILLION YEARS AGO,
MUCH OF THAT TREE WAS CUT BACK
WHEN A MASS EXTINCTION
WIPED OUT THE VAST MAJORITY
OF THE ANIMALS OF LAND AND SEA.
AS THE SUPERCONTINENT PANGEA BEGAN TO BREAK UP,
VOLCANOES PUMPED VAST AMOUNTS OF CARBON DIOXIDE
INTO THE AIR, ACIDIFYING THE OCEANS.
THE PLANET WARMED AND HABITATS WERE TRANSFORMED.
MOST OF THE TRIASSIC CROCODILE RELATIVES,
INCLUDING POPOSAURUS AND LITTLE FOOT, DIED OUT.
EXTINCTIONS ARE OF GREAT INTEREST
TO EVOLUTIONARY BIOLOGISTS,
BECAUSE THEY BASICALLY RESET THE EVOLUTIONARY GAME.
EVERY ONCE IN A WHILE, DURING THE HISTORY OF LIFE
THERE HAVE BEEN CATASTROPHIC EVENTS OF SUCH MAGNITUDE
THAT THOUSANDS OR MILLIONS OF SPECIES WERE WIPED OUT
IN WHAT BASICALLY IN DEEP TIME IS A SINGLE MOMENT.
THERE HAVE BEEN FIVE
MAJOR EXTINCTIONS IN EARTH'S HISTORY.
THROUGH THE LENS OF DEEP TIME,
WE CAN SEE THEY CAUSED PROFOUND DESTRUCTION,
AND CHANGED THE HISTORY OF LIFE ON EARTH.
THE MASS EXTINCTION THAT ENDED THE TRIASSIC PERIOD
USHERED IN A NEW CHAPTER IN THE STORY OF CROCS.
IN THE JURASSIC AND CRETACEOUS PERIODS,
CROCS FLOURISHED AGAIN,
BUT IN NEW AND EVEN STRANGER WAYS.
A RECORD OF THOSE WONDROUS CREATURES IS PRESERVED
IN ONE OF THE MOST SPECTACULAR LANDSCAPES ON EARTH,
PATAGONIA.
MANY GROUPS DIVERSIFIED IN THE JURASSIC.
DINOSAURS WERE CERTAINLY THE MOST CONSPICUOUS,
BECAUSE THEY WERE BIG,
BUT OTHER GROUPS BEGAN TO DIVERSIFY
IN A VERY, VERY IMPRESSIVE WAY,
AND CROCS WERE ONE OF THEM.
FOR THE DURATION OF THE JURASSIC
AND CRETACEOUS PERIODS, ALMOST 150 MILLION YEARS,
CROCS VIED WITH DINOSAURS FOR DOMINANCE.
THEY STOPPED BEING ONLY THE LAND ANIMALS
THEY WERE IN THE TRIASSIC
AND EXPERIMENTED WITH RADICALLY NEW WAYS OF BEING.
YOU START SEEING ANIMALS LIKE DAKOSAURUS
IS THE SWIMMING MARINE CROC
THAT ADAPTED THEIR FORELIMBS INTO PADDLE-LIKE FLIPPERS.
AND THEN YOU HAVE FRESHWATER GIGANTIC CROCS
LIKE SARCOSUCHUS THAT'S ABOUT 12 METER LONG,
THAT WAS EATING DINOSAURS.
AND THEN YOU HAVE HERBIVOROUS CROCS LIKE NOTOSUCHIANS.
LOOK AT THIS ANIMAL.
IT REALLY LOOKS NOTHING LIKE A CROC
IT HAS A SHORT SNOUT, VERY HIGH,
THE EYE SOCKETS ARE POINTING TO THE SIDES,
AND THE CRAZY, CRAZY THING IS THAT
IT MOVED THE LOWER JAW BACK AND FORTH.
AND THIS WAS A WAY OF THE UPPER TEETH AND LOWER TEETH
TO SLIDE AGAINST EACH OTHER
AND IN THAT WAY THIS ANIMAL WAS PROCESSING THE PLANT MATTER.
SO HERE WAS AN ANCIENT CROC
THAT CHEWED LIKE A GOAT.
DIEGO HAS SPENT MUCH OF THE LAST 20 YEARS
EXCAVATING ANCIENT CROCS
FROM THE BARREN OUTCROPS OF PATAGONIA.
BUT BACK WHEN THOSE CREATURES LIVED,
THE WORLD WAS A VERY DIFFERENT PLACE.
IT WAS MUCH WARMER PLANET.
THERE WERE NO ICE CAPS ON THE POLES.
IN THE WARMING GREENHOUSE WORLD
OF THE JURASSIC AND CRETACEOUS, CROCS PROSPERED.
THIS WAS THEIR GOLDEN AGE.
THEY BECAME SO DIVERSE THAT IN SOME PLACES YOU GO,
AND YOU BASICALLY ONLY FIND CROCS.
SO, WE CAN SEE A REALLY,
REALLY CRAZY DIVERSITY IN THE CRETACEOUS.
AND THEN ABOUT 66 MILLION YEARS AGO,
IT ALL WENT AWAY.
WHAT HAPPENED TO THE MANY CRETACEOUS CROCS?
IT SEEMS MOST OF THEM PERISHED
THE SAME WAY AS THE DINOSAURS.
IT WAS LONG REALIZED THAT AROUND 66 MILLION YEARS AGO
THERE WAS A MAJOR EXTINCTION OF ANIMALS AND PLANTS
ON LAND AND IN THE OCEANS.
ON LAND THE MOST FAMOUS CAUSALITY WAS THE DINOSAURS.
SCIENTISTS AGREE THAT AN ASTEROID STRIKE
BROUGHT ON THE GLOBAL DEVASTATION,
BUT MANY NOW ARGUE
IT WAS NOT THE ONLY CAUSE OF THE MASS EXTINCTION.
FROM THE FOSSIL RECORD, THEY CAN SEE THAT CLIMATE CHANGES
WERE ALREADY PUSHING MANY SPECIES TO EXTINCTION
BEFORE THE ASTEROID IMPACT.
SO BASICALLY, THIS IMPACT IS SORT OF THOUGHT
IF NOT THE SOLE CAUSE OF THE EXTINCTION,
CERTAINLY THE COUP DE GRACE FOR A GREAT MANY LINEAGES.
ANCIENT CROCS WERE REDUCED
TO A FRACTION OF WHAT THEY ONCE HAD BEEN.
SO OUT OF THIS WONDERFUL DIVERSITY
ONLY A FEW SPECIES MADE IT THROUGH.
AND THE ONES THAT ACTUALLY MADE IT THROUGH
WERE VERY PARTICULAR IN MANY WAYS.
THEY WERE CERTAINLY ADAPTED TO LIVING
IN THE FRESHWATER ENVIRONMENT.
THEY WERE ADAPTED TO FEEDING IN WATER.
THEY WERE PREDATORS, THEY WERE NOT HERBIVORES.
THEY WERE NOT LAND CROCODILES.
THEY WERE NOT MARINE CROCODILES.
SO ONLY A TINY FRACTION OF THAT DIVERSITY MADE IT THROUGH.
THE CROCODILES THAT MADE IT THROUGH
WERE THE SHORELINE PREDATORS
THAT LIVED HALF IN WATER AND HALF ON LAND.
THEIR LOW, TANK-LIKE BODY PLAN
MAY HAVE BEEN ONE SECRET OF THEIR SURVIVAL.
IT ALLOWS THEM TO LAY SEMI-SUBMERGED IN THE SHALLOWS
AND AMBUSH THEIR PREY WITH FEROCIOUS SPEED.
THE SUCCESS OF THAT LETHAL DESIGN
IS WHY CROCODILES TODAY ALL SEEM SO SIMILAR.
CROCODILES HAVE THIS FORM
THAT'S VERY, VERY SUCCESSFUL.
THEY HAVE SORT OF AN ARMORED BODY PLAN
THAT ALLOWS THEM TO BE A SUCCESSFUL PREDATOR
IN AQUATIC ENVIRONMENTS.
AQUATIC ENVIRONMENTS CAN BE MORE STABLE
THAN OTHER KINDS OF ENVIRONMENTS,
LIKE TERRESTRIAL ENVIRONMENTS.
AND SO, IT MAKES SENSE THAT THEY'VE RETAINED
THIS BODY PLAN FROM DEEP TIME,
FROM THE ANCESTRAL CROCODILIANS
THAT WERE AROUND THE GLOBE MILLIONS OF YEARS AGO.
IT WORKS REALLY WELL, WHY CHANGE IT?
OF COURSE, THAT CLASSIC BODY PLAN
IS NO GUARANTEE OF SURVIVAL.
THE HORNED CROC OF MADAGASCAR DIED OUT JUST CENTURIES AGO,
LIKELY PUSHED OUT BY THE GIANT NILE CROC.
RESULTS FROM EVON'S WORK
SUGGEST THE SPECIES ARE MORE CLOSELY RELATED
THAN ANYBODY REALIZED.
IT'S A GREAT EXAMPLE OF HOW DNA ANALYSIS
HAS BECOME A VITAL TOOL FOR PALEONTOLOGISTS.
ONE OF THE EXCITING THINGS
ABOUT THE NEW TOOL KIT WE HAVE TODAY,
THE ABILITY TO USE DNA TO LOOK AT EVOLUTIONARY HISTORY,
IS WE CAN USE IT AS SORT OF A METRIC
FOR CHANGE OVER TIME AND LINEAGES.
SO, WITH LIVING SPECIES, WE CAN TAKE THEIR DNA
AND WE CAN CALCULATE BACK HOW LONG IT TAKES
TO ACCUMULATE THE NUMBER OF CHANGES WE SEE IN THE GENOME.
AND WE CAN SAY,
THIS CORRESPONDS TO A SPLIT THREE MILLION YEARS AGO,
OR SIX MILLION YEARS AGO, OR 20 MILLION YEARS AGO.
DNA HAS SHOWN THAT BOTH CROCODILES AND ALLIGATORS
ARE DESCENDED FROM A COMMON ANCESTOR
THAT LIVED 80 MILLION YEARS AGO.
AND THEN, EVEN MORE RECENTLY,
THIS THING THAT WE'VE ALWAYS THOUGHT
AS THE SORT OF PRIMORDIAL CROCODILE, THE NILE CROCODILE,
WE RECENTLY HAVE FOUND USING MOLECULAR CLOCK DATING
THAT THE NILE CROCODILE IS JUST A BABY.
IT JUST AROSE PROBABLY WITHIN
THE LAST FOUR TO SIX MILLION YEARS.
IT'S A YOUNG'UN ON THE LANDSCAPE OF
CROCODILIANS IN THE MODERN WORLD.
SO, DESPITE THEIR PRE-HISTORIC APPEARANCE,
IT TURNS OUT THAT OVER THEIR 230 MILLION YEAR HISTORY,
CROCODILES HAVE BEEN IN CONSTANT EVOLUTION.
THEY HAVE PROVED THEMSELVES
TO BE ONE OF THE MOST RESILIENT LINEAGES
ON THE FACE OF THE PLANET.
FOR ME, THESE CROCODILES
SORT OF REPRESENT AN ORGANISM THAT
THROUGH THE HISTORY OF LIFE ON EARTH,
IT'S FOUND A WAY TO PERSIST.
THE STORY OF THE CROCODILE LINEAGE
IS OF DEEP TIME TRANSFORMATIONS
THAT PRODUCED A WILD DIVERSITY OF CROC SPECIES,
FOLLOWED BY A STEEP DECLINE.
TODAY THERE ARE JUST A HANDFUL OF CROCS
AND THE STRANGE ANIMALS THAT GAVE RISE TO THEM ARE ALL GONE.
THE SURVIVING CROCS ARE ALL VERY SIMILAR,
ALL SHORELINE PREDATORS OF THE TROPICS.
BUT WHILE THE CROCODILE LINEAGE HAS BOTTLENECKED,
ANOTHER LINEAGE IS EXPERIENCING
A WILD EXPLOSION OF DIVERSITY.
BIRDS HAVE COLONIZED EVERY ENVIRONMENT ON EARTH.
AND THEY COME IN AN ASTONISHING VARIETY
OF SHAPES, COLORS, AND SIZES.
THERE ARE MORE SPECIES OF BIRDS
THAN ANY OTHER GROUP OF VERTEBRATES THAT LIVES ON LAND.
THEY CAN CROSS THE HIMALAYAS ON WING.
THEY CAN DIVE INTO A PART OF THE OCEAN
WHERE SUNLIGHT DOES NOT REACH.
THEY CAN MIGRATE BETWEEN CONTINENTS.
SO, THEY ARE TRULY REMARKABLE.
BIRDS HAVE COLONIZED
NOT ONLY THE NATURAL ENVIRONMENTS OF THE PLANET
BUT ALSO THE URBAN SPACES CREATED BY HUMANS.
THERE ARE MORE THAN 10,000 SPECIES OF BIRDS,
BUT EVEN MORE STRIKING THAN THAT,
THERE ARE MORE THAN HALF THAT NUMBER
IS JUST WITHIN ONE LINEAGE, SONGBIRDS.
SO THAT MEANS THE BIRDS THAT ARE IN YOUR BACKYARD
ARE PART OF WHAT IS TRULY AN EXTRAORDINARY EVOLUTION.
SO, WHAT'S THE STORY
BEHIND THE SPREAD OF BIRDS ACROSS THE PLANET?
HOW DID THEY COME TO BE EVERYWHERE AND SO DIVERSE?
THINGS THAT CAN SEEM SO COMMONPLACE,
CROWS OR PIGEONS IN A PARK
ARE THE LEAVINGS OF AN AMAZING HISTORY
THAT STRETCHES BACK HUNDREDS OF MILLIONS OF YEARS.
OUR UNDERSTANDING OF THAT EVOLUTIONARY HISTORY
BEGAN WITH ONE EXTRAORDINARY FOSSIL
DISCOVERED IN THE 1860'S IN GERMANY,
ARCHAEOPTERYX.
THIS FOSSIL, TO MANY PEOPLE,
MIGHT JUST LOOK LIKE ROAD KILL
OR SOMETHING THAT HIT YOUR WINDOW.
BUT IN FACT, TO ME THESE BONES, THEY COME TO LIFE.
AND THE WINGS ARE MOVING,
COVERED IN FEATHERS,
BUT WITH MOBILE CLAWS AT THEIR TIPS.
MOST STRIKING IS A LONG, BONY TALE WITH FEATHERS.
150 MILLION-YEARS-OLD,
ARCHAEOPTERYX WAS A BIRD.
IT HAD FEATHERS AND IT COULD FLY.
BUT WITH ITS CLAWS, TAIL AND TOOTHED BEAK,
THERE WAS SOMETHING ALMOST DINOSAUR-LIKE ABOUT IT.
IT LED PROPONENTS OF THE NEW THEORY OF EVOLUTION
TO MAKE A SENSATIONAL CLAIM.
BIRDS MUST HAVE EVOLVED FROM DINOSAURS.
WHEN I LOOK AT THIS, I SEE AN ICON OF EVOLUTION.
IT WAS ONE OF THE FIRST KEY
AND TOTALLY UNAVOIDABLE PIECES OF EVIDENCE
CONSISTENT WITH EVOLUTION.
BUT THE THEORY THAT BIRDS EVOLVED FROM DINOSAURS
MET INTENSE OPPOSITION.
HOW COULD SOMETHING SO HUGE AND HEAVY
EVOLVE INTO SOMETHING SO SMALL AND LIGHT?
ONE OF THE BIGGEST OBJECTIONS
WAS THAT NO DINOSAUR HAD EVER BEEN FOUND WITH A WISHBONE,
IN BIRDS, THE CRUCIAL BRACE FOR THE CHEST
THAT MAKES FLIGHT POSSIBLE.
THE SEARCH WAS ON.
IF SCIENTISTS COULD FIND A DINOSAUR WITH A WISHBONE,
THEY WOULD CLINCH THE CASE,
BUT FOR A CENTURY, THEY FAILED.
THEN IN THE 1960'S,
PALEONTOLOGIST JOHN OSTROM HIT PAY DIRT.
A DINOSAUR FOSSIL, WITH A WISHBONE.
HE CALLED IT DEINONYCHUS, TERRIBLE CLAW.
HERE WE HAVE DEINONYCHUS ANTIRRHOPUS,
THE FOSSIL THAT CHANGED EVERYTHING THAT WE KNOW
ABOUT THE ORIGIN OF BIRDS
AND FUNDAMENTALLY ALTERED OUR UNDERSTANDING
OF HOW FLIGHT EVOLVED.
DEINONYCHUS WAS A FEROCIOUS PREDATOR
WITH WING-LIKE ARMS
AND ALL THE BONES AND MUSCLES NECESSARY FOR FLIGHT.
BUT IT COULDN'T FLY.
HERE'S AN ANIMAL WITH FORELIMBS MUCH TOO SHORT
AND MUCH TOO HEAVY IN THE BODY TO BE ABLE TO FLY,
YET IT HAS ALL THE BELLS AND WHISTLES
THAT WE ASSOCIATE WITH THE FLIGHT STROKE.
NOT ONLY THAT, IT HAD FEATHERS TOO.
BUT ALL THIS HAD NOTHING TO DO WITH FLIGHT.
ITS FEATHERS WERE FOR WARMTH
AND ITS CLAWED WINGS WERE FOR KILLING.
THE ARMS UP AGAINST THE BODY,
AND YOU SHOOT IT DOWN AND FORWARD,
GRAB YOUR PREY, DRAG IT UP AND BACK.
DOWN AND FORWARD, UP AND BACK,
DOWN AND FORWARD, UP AND BACK.
THAT'S THE FLIGHT STROKE.
SO, ALL THE DETAILS,
THE BASIC ARCHITECTURE, AT LEAST, OF THE FLIGHT STROKE
IS EVOLVED IN AN ANIMAL THAT IS NOT USING IT TO FLY.
AMAZINGLY, THESE TOOLS BUILT FOR KILLING
WOULD EVENTUALLY POWER FLIGHT.
SO YOU HAVE FEATHERS AND YOU HAVE THE FLIGHT STROKE
COLLIDING IN ONE ANIMAL,
SO THE SKIES WERE NO LONGER A BARRIER
TO THE EVOLUTION OF DINOSAURS.
AND THAT'S WHY WE THINK THAT BIRDS ARE LIVING DINOSAURS.
DEINONYCHUS WAS POWERFUL EVIDENCE
THAT DINOSAURS GAVE RISE TO BIRDS.
BUT THE MANY STAGES OF THAT EVOLUTION WERE STILL UNKNOWN.
TO COMPLETE THE STORY, SCIENTISTS NEEDED MORE FOSSILS.
ANOTHER LONG WAIT BEGAN.
THEN IN THE 1990'S,
FARMERS IN A REMOTE PROVINCE OF NORTHEASTERN CHINA
BLEW THE STORY OF BIRD EVOLUTION WIDE OPEN.
THEY HAD BEEN TURNING UP ROCKS
WITH THE OUTLINES OF BIRDS IN THEM
FOR AS LONG AS THEY COULD REMEMBER.
THEY HAD NO IDEA THESE WERE THE BIRD/DINOSAUR FOSSILS
SCIENTISTS HAD BEEN WAITING FOR.
BY THE LATE 1990'S,
FOSSIL FEVER HAD BROKEN OUT IN LIAONING PROVINCE.
AT FIRST, NOBODY KNEW HOW VALUABLE THEY WERE.
BUT THEN WE FOUND OUT.
WE ALL STARTED TO DIG.
I DID TOO.
I FOUND SOMETHING THAT LOOKED LIKE A BIRD.
I DIDN'T KNOW WHAT IT WAS,
BUT THEY SAID IT WAS SOMETHING CALLED CONFUCIUSORNIS.
A SINGLE FOSSIL COULD BRING A YEAR'S INCOME.
AS FARMERS SCOURED THE LANDSCAPE,
THE FOSSILS STARTED TO POUR IN,
HUNDREDS OF ANCIENT BIRDS FROM THE TIME OF THE DINOSAURS.
THE FOSSILS FROM WESTERN LIAONING
STARTED TO SHOW US THE TRANSITIONAL FORMS.
THEY SHOWED US THE EARLIEST BIRDS WITH BEAKS,
THE EARLIEST BIRDS WITH SHORT TAILS, LIKE LIVING BIRDS.
BIRD FOSSILS ARE EXTREMELY RARE
BECAUSE BIRD BONES ARE SO DELICATE.
BUT HERE IN NORTHEASTERN CHINA, 130 MILLION YEARS AGO,
A UNIQUE COMBINATION OF CIRCUMSTANCES
CREATED THE PERFECT CONDITIONS FOR THEIR PRESERVATION.
IF YOU WERE ABLE TO COME BACK HERE
131 TO 120 MILLION YEARS AGO AND LOOKED OUT,
YOU WOULD HAVE SEEN LAKES AS FAR AS THE EYE COULD SEE,
WITH ACTIVE VOLCANOES GOING OFF AROUND THEM
AND A FORESTED ENVIRONMENT
GROWING BY THE SHORES OF THESE LAKES.
AND THIS FOREST WOULD HAVE BEEN TEEMING
WITH SMALL, FEATHERED DINOSAURS.
AS THOSE SMALL FEATHERED DINOSAURS DIED
AND FELL OR WERE WASHED INTO LAKES,
THEY WERE QUICKLY BURIED IN LAYERS OF VOLCANIC ASH.
THE RESULT?
AN EXTRAORDINARY RECORD OF CRETACEOUS BIRD/DINOSAURS
PERFECTLY PRESERVED IN STONE.
THE AMAZING THING ABOUT THESE FOSSILS
IS THE EXCEPTIONAL PRESERVATION OF SOFT TISSUES,
WHICH REVEAL THESE EXTINCT ANIMALS IN A LEVEL OF DETAIL
THAT WE PALEONTOLOGISTS NEVER PREVIOUSLY THOUGHT POSSIBLE.
FOSSILIZED ALONG WITH THE BIRDS
WERE PLANTS AND SEEDS,
ALLOWING SCIENTISTS TO RECONSTRUCT
THE FORESTED ENVIRONMENT OF THE TIME.
TOGETHER, THE WEALTH OF LIAONING FOSSILS
REVEAL A WORLD WHERE CREATURES REPRESENTING
EVERY STAGE OF DINOSAUR TO BIRD EVOLUTION
LIVED SIDE BY SIDE.
THEY SHOW HOW NATURE EXPERIMENTED
WITH EVERY ASPECT OF WHAT WOULD FINALLY MAKE A BIRD,
BEAKS, WINGS, FEATHERS, AND FLIGHT.
THERE WAS CAUDIPTERYX,
A SMALL FEATHERED DINOSAUR THAT HAD WINGS BUT COULDN'T FLY.
LIVING ALONGSIDE IT WERE CREATURES THAT FLEW
BUT STILL HAD MANY DINOSAUR CHARACTERISTICS,
TEETH, LONG TAILS, AND CLAWS ON THEIR WINGS,
AND THERE WERE CREATURES LIKE CONFUCIUSORNIS,
ALMOST IDENTICAL TO MODERN BIRDS.
THE FEATHERED DINOSAURS OF LIAONING ARE A REMINDER
THAT EVOLUTION DOES NOT MOVE IN A STRAIGHT LINE.
THERE'S A COMMON PERCEPTION
THAT EVOLUTION PROCEEDS IN A VERY LINEAR FASHION.
SO YOU HAVE A LITTLE DINOSAUR
THAT SOMEHOW DECIDES, QUOTE/UNQUOTE, TO BECOME A BIRD.
BUT ACTUALLY, THE MANY BIRD FEATURES
WERE GRADUALLY ACQUIRED.
THERE WERE A LOT OF DEAD ENDS IN THIS EVOLUTIONARY PROCESS.
JUST LIKE DEINONYCHUS,
THE LIAONING FOSSILS SHOW THAT WINGS
AND FEATHERS EVOLVED SEPARATELY
AND FOR REASONS THAT HAVE NOTHING TO DO WITH FLIGHT.
IT WAS ONLY AFTER MILLIONS OF YEARS
THAT THESE THINGS CAME TOGETHER
TO MAKE THE CREATURE WE CALL A BIRD.
IN FACT, WHAT WE'VE LEARNED
FROM THIS HUGE DIVERSITY OF FOSSILS
IS THAT THESE FEATURES THAT WE ASSOCIATE WITH MODERN BIRDS
ACTUALLY EVOLVED MULTIPLE TIMES.
THE LIAONING FOSSILS OPENED A WINDOW
ON THE PROFUSION OF FEATHERED DINOSAURS
THAT POPULATED THE WHOLE WORLD
MANY MILLIONS OF YEARS AGO.
WHAT HAPPENED TO THEM ALL?
MOST DIED OUT IN THE SAME EXTINCTION EVENT
THAT KILLED THE BIG TERRESTRIAL DINOSAURS AND MOST CROCS.
BUT LIKE THE CROCS, A FEW BIRDS SQUEAKED THROUGH.
THOSE FEW SURVIVORS GAVE RISE
TO ALL THE BIRD ON EARTH TODAY.
HOW DID THAT AMAZING STORY OF SURVIVAL PLAY OUT?
REMARKABLY, THE SCIENTISTS ARE SOLVING THAT MYSTERY,
NOT FROM BONES, BUT FROM DNA.
SO WHAT HAPPENED IS THAT THIS MASS EXTINCTION OCCURS,
MAYBE AS A RESULT OF A BIG, GIANT METEORITE,
THEN CLIMATE CHANGE AND SO FORTH.
A FEW GROUPS OF BIRDS SURVIVE,
ONLY FIVE PERCENT OF THE SPECIES SURVIVE.
ERICH AND HIS COLLEAGUES
COMPARED THE GENOMES OF DIFFERENT BIRD SPECIES
TO CALCULATE THEIR DEGREES OF SIMILARITY.
THEY COULD THEN FIGURE OUT
WHEN THEY LAST SHARED COMMON ANCESTORS.
FIRST THING WE FIGURED OUT IS THAT
THOSE ONES THAT SURVIVED,
WITH THE DEEPEST BRANCHES IN THE TREE THAT WE GENERATED
WERE THE ONES THAT WERE SHORE BIRDS,
THAT CAN SURVIVE IN WATER, THAT CAN SURVIVE IN LAND,
THAT SURVIVE IN DIFFERENT HABITATS.
ALONG WITH SHORE BIRDS LIKE DUCKS AND GEESE,
THE ANCESTORS OF OSTRICHES AND EMUS ALSO SURVIVED.
THEN THOSE FEW FOUR OR FIVE LINEAGES THAT SURVIVE,
IN A 15-MILLION-YEAR WINDOW,
GAVE RISE TO EVERY SPECIES THAT WE ARE LOOKING AT NOW TODAY.
SCIENTISTS ARE FINALLY IN A POSITION
TO SEE THE WHOLE VAST AVIAN TREE OF LIFE.
ARISING WITH THE DINOSAURS, THE BIRD LINEAGE EXPERIMENTED
FOR MILLIONS OF YEARS WITH FEATHERS, BEAKS AND WINGS.
IT BARELY SURVIVED A MAJOR EXTINCTION EVENT
BEFORE FINALLY FLOWERING IN THE 10,000 SPECIES ALIVE TODAY.
BUT WHILE THE BIRD LINEAGE EXPLODED
AND BIRDS COLONIZED EVERY HABITAT ON EARTH,
ANOTHER LINEAGE CONCENTRATED ON COLONIZING JUST THE SEAS.
FOR AS LONG AS HUMANS HAVE KNOWN THEM,
WHALES HAVE INSPIRED FEAR AND WONDER.
HOW COULD THESE GIANTS OF THE DEEP
HAVE GROWN SO HUGE?
HOW COULD AIR-BREATHING CREATURES LIKE US
HAVE COME TO LIVE IN THE DEPTHS OF THE OCEAN?
WHAT SCIENCE NOW KNOWS ABOUT
THESE LEVIATHANS OF THE DEEP IS AMAZING.
BOWHEAD WHALES CAN LIVE FOR UP TO 200 YEARS,
LONGER THAN ANY OTHER MAMMAL ON EARTH.
SPERM WHALES CAN DIVE TO DEPTHS OF OVER 3000 FEET
AND STAY UNDERWATER FOR AN HOUR AND A HALF
WITHOUT BREATHING.
BLUE WHALES ARE THE BIGGEST CREATURES
TO EVER HAVE LIVED ON EARTH,
BIGGER EVEN THAN THE LARGEST DINOSAURS.
UP TO A HUNDRED FEET LONG AND 200 TONS IN WEIGHT,
THEY HAVE A HEART THE SIZE OF A SMALL CAR.
AND THESE GIANTS OF THE DEEP SING TO EACH OTHER,
COMMUNICATING OVER VAST DISTANCES IN A LANGUAGE OF SONG
THAT RESEARCHERS STILL DON'T FULLY UNDERSTAND.
HOW DID THESE GARGANTUAN ANIMALS
AND THEIR REMARKABLE BEHAVIOR EVOLVE?
FOR SO LONG IT WAS A MYSTERY.
WE'VE KNOWN THAT THE WHALES ARE MAMMALS
SINCE THE 18TH AND 19TH CENTURIES,
BECAUSE THEY'RE WARM BLOODED AND THEY SUCKLE THEIR YOUNG,
BUT WE DIDN'T KNOW WHERE THEY CAME FROM.
DARWIN TALKED ABOUT THE ORIGIN OF WHALES
IN HIS CLASSIC BOOK THE ORIGIN OF SPECIES
WHERE HE SAID SOMEONE HE KNEW
HAD OBSERVED A BEAR SWIMMING AROUND,
SKIMMING INSECTS OFF THE SURFACE OF THE WATER
AND HE SUGGESTED THAT PERHAPS SOMETHING LIKE A BEAR
COULD HAVE EVOLVED INTO A WHALE,
THE KIND OF WHALE THAT FILTER FEEDS
BY DOING SOMETHING SIMILAR
AND GETTING BETTER AND BETTER AT IT OVER TIME.
NOW DARWIN WAS NOT CORRECT ABOUT THAT,
BUT AT LEAST HE COULD CONCEPTUALIZE
OF A WAY THAT WHALES HAD EVOLVED.
BUT BASICALLY, WE DIDN'T KNOW WHERE WHALES CAME FROM
UNTIL EXTREMELY RECENTLY.
THE FASCINATION WITH WHALE EVOLUTION
BEGAN IN THE 19TH CENTURY.
STORIES OF SEA MONSTERS FILLED THE POPULAR IMAGINATION.
WHEN THE FIRST FOSSIL WHALE WAS UNEARTHED,
ITS DISCOVERERS THOUGHT THEY'D FOUND A GIGANTIC SEA SERPENT.
IT WAS CALLED BASILOSAURUS.
IT WAS DISCOVERED IN NORTH AMERICA
ALONG THE GULF COAST IN THE 1830'S,
AND IT WAS ACTUALLY THE FIRST FOSSIL WHALE
EVER TO BE SCIENTIFICALLY NAMED AND STUDIED.
THE GENTLEMAN WHO NAMED IT, A MAN NAMED HARLAN,
HAD READ ABOUT LARGE SEA SERPENTS
BEING DISCOVERED ELSEWHERE IN THE WORLD,
AND SO HE THOUGHT THAT THIS WAS SOMETHING SIMILAR.
AND THUS HE NAMED THIS ANIMAL BASILOSAURUS,
WHICH MEANS KING LIZARD.
UP TO 50 FEET LONG WITH FEROCIOUS TEETH,
BASILOSAURUS WAS A FORMIDABLE MARINE PREDATOR.
FINALLY, IN 1841, IT WAS IDENTIFIED AS A WHALE
AND DATED TO ABOUT 35 MILLION YEARS AGO.
FOR ALMOST A CENTURY AFTER ITS DISCOVERY,
BASILOSAURUS REMAINED THE OLDEST KNOWN WHALE.
IT WAS ASSUMED TO BE THE ANCESTOR OF ALL LIVING WHALES.
SO AFTER THE DISCOVERY OF BASILOSAURUS,
THERE WERE OTHER WHALES FOUND
THAT WERE JUST A LITTLE BIT EARLIER AND MORE PRIMITIVE,
BUT NOT BY VERY MUCH,
MAYBE FIVE MILLION YEARS OLDER THAN BASILOSAURUS.
AND IT DIDN'T PUSH THE ORIGIN BACK IN TIME,
AND WE REALLY DIDN'T DISCOVER A WHOLE LOT MORE
ABOUT THE ORIGIN OF WHALES.
THE DEEP ORIGINS OF THE WHALE LINEAGE
WERE A MYSTERY UNTIL 1975,
WHEN A PALEONTOLOGIST WENT ON A FOSSIL HUNTING EXPEDITION
TO PAKISTAN.
HE WASN'T LOOKING FOR EARLY WHALES AT ALL.
I WAS INTERESTED IN HOW ARCHAIC MAMMALS
CHANGED INTO THE MODERN MAMMALS.
THINGS LIKE THE FIRST HORSES,
THAT'S WHAT I WAS INTERESTED IN.
I TOOK SEVERAL STUDENTS WITH ME AND COLLEAGUES FROM PARIS
AND WE LOOKED FIRST IN PUNJAB PROVINCE, THEN SOUTH IN SINDH.
WE STILL HADN'T FOUND ANYTHING VERY INTERESTING.
AND WE WENT TO THE NORTHWEST FRONTIER PROVINCE.
AND THERE, HIGH ON A HILL,
WE FOUND A LITTLE JAW OF A LAND MAMMAL.
LATER THEY FOUND A PIECE OF SKULL,
AND ITS STRANGE EAR BONES
FINALLY UNLOCKED THE SECRETS OF EARLY WHALE EVOLUTION.
THIS IS WHAT WAS LEFT, THE BACK OF A SKULL,
AND IF YOU LOOK AT THE UNDERSIDE,
IT HAS THE COVERING OF THE EAR ON THE RIGHT SIDE
AND THAT COVERING IS MISSING ON THE LEFT SIDE.
THOSE EAR BONES TURNED OUT TO BE THE KEY.
PHILIP THOUGHT HE WAS LOOKING AT THE SKULL
OF SOMETHING LIKE A PRIMITIVE DEER,
BUT IT UNMISTAKABLY HAD THE EAR BONES OF A WHALE.
WHALES HAVE A SPECIAL STRUCTURE OF THE EAR
TO BE ABLE TO HEAR IN WATER.
IT TURNS OUT THAT THEY EFFECTIVELY
SEE IN WATER BY USING SOUND.
AND SO TO DO THIS THE EARS HAVE BECOME MODIFIED.
THE EAR BONES OF WHALES ARE VERY DENSE,
AND THAT DENSITY HELPS THEM TO HEAR SOUND IN THE WATER.
MAMMAL EARS ORIGINALLY EVOLVED IN TERRESTRIAL ANIMALS,
AND SO THEIR STRUCTURE IS OPTIMAL FOR HEARING IN AIR.
AND IN WATER, SOUND BEHAVES REALLY DIFFERENTLY.
SO, FOR EXAMPLE, IF YOU GO INTO A POOL OR UNDER A LAKE,
YOU CAN HEAR SOUND BUT IT'S A LITTLE MUFFLED,
BUT THE ONE THING YOU CAN'T DO IS YOU CAN'T FIGURE OUT
WHERE THE SOUND IS COMING FROM AROUND YOU.
AND THAT'S BECAUSE THE WAY MAMMALS DO THIS IS,
IS THEY USE THE DIFFERENCE IN TIME BETWEEN
WHEN A SOUND HITS YOUR RIGHT EAR AND YOUR LEFT EAR
TO FIGURE OUT WHAT DIRECTION THE SOUND IS COMING FROM.
SO IF THE SOUND IS OFF TO MY RIGHT,
IT HITS MY RIGHT EAR FIRST, THEN MY LEFT EAR,
AND SO MY BRAIN SAYS THE SOUND IS OVER TO MY RIGHT.
BUT IN WATER, THE TISSUE OF YOUR FACE AND SKULL
IS ABOUT THE SAME DENSITY AS WATER.
SO THE SOUND, RATHER THAN GOING AROUND MY SKULL
TO MY LEFT EAR, GOES RIGHT THROUGH IT.
SO IT GETS TO MY LEFT EAR
AT ALMOST THE SAME TIME AS MY RIGHT EAR.
AND I CAN'T TELL WHERE THE SOUND IS COMING FROM.
SO THE ADDED DENSITY TO WHALE EARS
IS REESTABLISHING THEIR ABILITY
TO HEAR DIRECTIONALLY UNDERWATER.
PHILIP'S FOSSIL HAD THAT SAME DISTINCTIVE EAR,
AND IT WAS 49 MILLION YEARS OLD.
THAT COULD ONLY MEAN ONE THING.
HERE AT LAST WAS ONE OF THE VERY FIRST WHALES.
PHILIP NAMED IT PAKICETUS.
ONCE WE KNEW IT WAS A WHALE,
WE KNEW IT WAS THE OLDEST WHALE ANYONE HAD EVER FOUND.
PAKICETUS PUSHED THE ORIGINS OF WHALES
BACK 15 MILLION YEARS
TO THE TIME WHEN THE INDIAN SUBCONTINENT
WAS SLOWLY CRASHING INTO ASIA.
WHERE PAKICETUS WAS FOUND WAS ONCE AN OCEAN SHORELINE,
ITS EARS MADE IT CLEAR PAKICETUS SPENT TIME UNDERWATER,
BUT OTHER FRAGMENTS OF SKELETON
ALSO CLEARLY SHOWED IT WALKED ON FOUR LEGS.
HOW DID THIS STRANGE BEAST GIVE RISE
TO THE GIANTS WE KNOW TODAY?
AT THE MUSEUM OF NATURAL HISTORY IN PARIS,
ONE OF THE BIRTHPLACES OF PALEONTOLOGY,
THEY HAVE BEEN ASSEMBLING
THE SKELETONS OF PREHISTORIC ANIMALS FOR OVER 200 YEARS.
THEY NOW HAVE ONE OF THE FEW COMPLETE RECONSTRUCTIONS
OF THE EXTRAORDINARY WHALE ANCESTOR, PAKICETUS.
YOU SEE IT IS A QUADRUPEDAL ANIMAL
WITH THE HIGHER FORELIMBS AND HIND LIMBS.
IT MEANS THAT THIS ANIMAL WAS DEFINITELY PARTLY TERRESTRIAL.
AND OBVIOUSLY IT'S A QUITE A STRANGE ANIMAL,
VERY SMALL, DOESN'T WHALE-LOOKING AT ALL.
IT MORE LOOKS LIKE A DOG WITH A LONG SNOUT.
PAKICETUS IS ONE OF
THE STRANGEST SURPRISES OF EVOLUTION,
A WHALE ANCESTOR THAT LOOKS LIKE A SMALL WOLF
WITH WEBBED FEET FOR SWIMMING.
THE KEY THING ABOUT IT IS,
IT HAS ELONGATED FINGER AND TOE BONES,
SO CLEARLY IT'S ALREADY SEMI AQUATIC.
PAKICETUS WAS A CREATURE OF THE SHORELINE,
HUNTING FOR FISH
AND PERHAPS OTHER SMALL ANIMALS IN THE SHALLOWS.
AND WE THINK THAT IT WAS USING ITS LONGER SNOUT
TO PROBE FOR AQUATIC PREY IN THE WATER.
AND SO IT WAS FEEDING IN THE WATER,
WHILE ALMOST CERTAINLY GOING OUT ON LAND
TO BREED AND HAVE THEIR YOUNG.
ONCE THEY ADAPTED TO LIFE IN THE SHALLOWS,
IT TOOK 10 MILLION YEARS FOR THE DESCENDENTS OF PAKICETUS
TO BECOME FULLY AQUATIC.
WHY DID IT TAKE SO LONG?
BECAUSE TO LIVE UNDER WATER, THEY HAD TO CHANGE!
IT IS ONE OF THE MOST REMARKABLE STORIES
OF TOTAL PHYSICAL TRANSFORMATION IN THE ANNALS OF EVOLUTION.
AFTER PAKICETUS,
WHALES TAKE ABOUT 10 TO 12 MILLION YEARS
TO EVOLVE INTO FULLY AQUATIC FORMS.
AND DURING THAT TIME THEIR HIND LIMBS TEND TO GET SMALLER
AND THEIR SKULLS TEND TO GET LONGER.
AND THE NARIS, WHICH IS THE HOLE IN THE SKULL
WHERE THE NOSE IS, MOVES UP THE SKULL.
IN ADDITION, THEIR FORELIMBS TEND TO TURN INTO FLIPPERS,
AND THEY GET MORE VERTEBRAE IN THEIR BACK,
WHICH MAKES THEIR BODIES LONGER.
BUT THERE WAS STILL ONE GREAT TRANSFORMATION
TO TAKE PLACE IN WHALES,
BALEEN FEEDING.
SO NEAR THE BASE OF THE WHALE FAMILY TREE
THERE'S THIS MAJOR SPLIT
INTO THE TWO GROUPS THAT WE HAVE TODAY.
WE HAVE TOOTHED WHALES AND THEN WE HAVE BALEEN WHALES
THAT ACTUALLY LOSE THEIR TEETH ENTIRELY.
AND THEY GROW WHAT ARE CALLED BALEEN PLATES
THAT ARE MADE OF KERATIN.
SO THEY'RE ACTUALLY MORE LIKE HAIR OR FINGERNAILS.
AND THESE WHALES USE IT TO FILTER THEIR FOOD.
SO THEY'LL TAKE BIG GULPS OF WATER
AND THEY'LL ACTUALLY FILTER THEIR PREY,
LITTLE TINY MICROSCOPIC ORGANISMS,
OUT OF THAT WATER USING THE BALEEN PLATES.
THE SPLIT INTO TOOTHED WHALES
LIKE ORCAS AND DOLPHINS,
AND BALEEN WHALES, LIKE BLUE WHALES AND HUMPBACKS
HAPPENED ABOUT 30 MILLION YEARS AGO.
THE TOOTHED WHALES REMAINED, LIKE THEIR ANCIENT ANCESTORS,
PREDATORS, LIVING MOSTLY IN COASTAL WATERS.
THERE THEY COULD FEED ON FISH,
OR LIKE SOME OF THE ORCAS, SEALS, AND BABY SEA LIONS.
THE BALEEN FEEDERS
UNDERWENT A MUCH GREATER TRANSFORMATION.
WITH A RADICALLY NEW WAY OF FILTER FEEDING,
THEY MOVED INTO THE DEEP OCEANS AND BECAME HUGE.
WHY?
FOR A LONG TIME, THE MASSIVE SIZE OF SOME BALEEN WHALES
WAS A PUZZLE.
BUT IT TURNS OUT THAT IN THE OCEAN,
GREAT SIZE IS AN ADVANTAGE.
IF YOU LOOK AT THE ENERGY BUDGET OF THESE ANIMALS,
THEY USE FEWER CALORIES PER UNIT BODY MASS
WHEN YOU GET BIGGER.
AND SO, THEY'RE MORE EFFICIENT WHEN THEY'RE HUGE.
THEY'RE ALSO MORE EFFICIENT WHEN THEY MOVE,
WHEN THEY SWIM AT LARGE BODY SIZE.
SO THERE'S ADVANTAGES TO BEING LARGE IN THE OCEAN.
THE HUGE SIZE OF BALEEN WHALES IS ALSO LINKED
TO ONE OF THE LAST GREAT PLANETARY TRANSFORMATIONS.
ARGENTINA AND SOUTH AMERICA
BECOME COMPLETELY SEPARATE FROM ANTARCTICA.
AND THAT CHANGES THE CURRENTS IN THE OCEAN SYSTEM,
AND IT SEEMS TO REALLY HAVE A PROFOUND IMPACT
ON WHAT WHALES ARE DOING.
THE COLD CURRENT THAT BEGAN TO CIRCLE ANTARCTICA
LED TO A VAST UPSURGE IN THE KRILL POPULATION
THAT BALEEN WHALES FEED ON.
WITH LARGE AMOUNTS OF FOOD
AND THE EFFICIENT BALEEN FILTER FEEDING SYSTEM,
THERE WAS SIMPLY NOTHING TO STOP BALEEN WHALES
FROM BECOMING HUGE.
ALONG WITH BALEEN,
WHALES HAVE DEVELOPED SOPHISTICATED FISHING BEHAVIORS
TO TRAP THEIR PREY.
HUMPBACKS RELY ON THE HELP OF GULLS.
AND WHAT'S HAPPENING IS THE DIVING BIRDS
ARE FORCING THE HERRING TOGETHER, THAT FORM A HUGE BALL.
THAT GIVES THE GULLS AT THE SURFACE A CHANCE
TO PROPEL THEMSELVES DOWN AND TRY TO GRAB A HERRING
AND THEN SOMEHOW THE HUMPBACKS KNOW
THAT THERE'S A CONCENTRATION OF FEED THERE.
AND THEY COME WITH THEIR HUGE MOUTHS, GULP IT DOWN,
GET RID OF THE SALT WATER THROUGH THEIR BALEEN
AND SWALLOW.
JACKIE HAS BEEN WORKING
WITH THE HUMPBACK WHALE POPULATION
OFF NORTHERN VANCOUVER ISLAND FOR ALMOST 20 YEARS.
JACKIE'S WORK HAS LED HER TO MARVEL
AT THE DELICATE WEB OF RELATIONSHIPS LINKING HUMPBACKS
TO EVERY ASPECT OF THE MARINE ECOSYSTEM.
IT'S PERFECTION.
IT'S BEEN GOING ON LONGER THAN WE CAN UNDERSTAND.
KNOWING WHALES,
KEEPS ME IN A STATE OF HUMILITY AND MYSTERY,
WHICH I THINK IS HOW A HUMAN LIFE IS WELL LIVED.
IT MAKES ME FEEL CONNECTED.
IT MAKES ME FEEL APPROPRIATELY SMALL
IN THE PRESENCE OF GIANTS.
OVER MILLIONS OF YEARS,
WHALES GREW HUGE AS THEY EXPLORED THE SEAS,
BUT ANOTHER MAMMAL GREW HUGE AS IT EXPLORED THE EARTH,
EVOLVING ITS OWN REMARKABLE TOOLS FOR LIFE ON LAND.
FOR MILLENNIA THESE STATELY CREATURES
HAVE PATROLLED THE AFRICAN SAVANNAS,
TRANSFORMING THE LAND AS THEY GO.
WE'RE DRIVING ALONG TRACKS
THAT THE ELEPHANTS HAVE MADE.
THEY'VE BEEN WALKING ON THESE TRAILS
PROBABLY FOR HUNDREDS OF YEARS.
THEY CREATE PATHS THAT THEY THEN USE FOR GENERATIONS.
ELEPHANTS ARE SUCH EXTRAORDINARY ANIMALS.
THE MORE WE LEARN ABOUT THEM, THE MORE WE REALIZE THAT
WE ACTUALLY ARE ONLY JUST SCRATCHING THE SURFACE.
EVERY NEW DISCOVERIES EMERGE
THAT ELEPHANTS CAN UNDERSTAND THINGS
THAT WE COULDN'T HAVE DREAMED POSSIBLE.
AND I THINK WE'LL NEVER UNCOVER THEIR SECRETS.
SCIENTISTS HAVE SHOWN THAT ELEPHANTS COMMUNICATE
THROUGH CALLS, TOUCH, AND EVEN LOW FREQUENCY VIBRATIONS,
WHICH CAN TRAVEL UNDERGROUND FOR MILES.
BUT THERE'S STILL A LOT THAT THEY DON'T FULLY UNDERSTAND.
IT WOULD BE AMAZING IF WE COULD ACTUALLY
UNCOVER WHAT IT IS THAT THEY KNOW.
I REALLY THINK THAT WE ARE BLUNDERING ABOUT RIGHT NOW
BECAUSE WE DON'T EVEN HAVE THE TOOLS
TO MEASURE HOW THEY COMMUNICATE.
AND PAULA IS CERTAIN
THAT ALONG WITH THEIR ABILITY TO TALK TO EACH OTHER,
THEY EXPERIENCE MANY OF THE SAME EMOTIONS WE FEEL,
GRIEF, ANGER AND EMPATHY.
SHE SENSES A MYSTERIOUS INNER LIFE.
WHEN YOU SIT WITH THEM FOR HOURS,
THIS LIKE WEALTH OF SENSATIONS
JUST KEEP COMING AND COMING AND COMING
AND IT JUST SEEMS TO BE ENDLESS.
I FEEL LIKE I CAN REALLY SENSE
WHAT IS GOING ON WITH THOSE ELEPHANTS.
AND THE LONGER I SPEND WITH ELEPHANTS,
THE MORE I FEEL IN TUNE WITH THEM.
AS MUCH AS SHE ADMIRES THEM,
PAULA IS KEENLY AWARE THAT ELEPHANTS TODAY ARE IN TROUBLE.
THERE USED TO BE DOZENS OF SPECIES OF ELEPHANTS.
AND NOW THERE ARE JUST THREE.
AND IF WE'RE NOT CAREFUL WE WILL LOSE THEM AS WELL,
AND THAT WILL BE THE END OF THE LINEAGE OF ELEPHANTS.
COULD THE ANCIENT LINEAGE OF ELEPHANTS
REALLY BE COMING TO AN END?
HOW DID THESE MAGNIFICENT ANIMALS
GO FROM MYRIAD SPECIES TO JUST THREE TODAY?
AND HOW DID THE ANCIENT HISTORIES OF
HUMANS AND ELEPHANTS
BECOME SO INTERTWINED?
AS WITH EVERY LINEAGE IT'S A STORY THAT BEGINS IN DEEP TIME,
A STORY TOLD BY FOSSILS,
MOST OF THEM FOUND IN THE BIRTHPLACE OF ELEPHANTS,
AFRICA.
THE DEEP ORIGINS OF ELEPHANTS LIE IN THE TURKANA BASIN
IN NORTHERN KENYA.
IN A PLACE CALLED BULUK, SCIENTISTS ARE FINDING FOSSILS
THAT POINT TO A MAGNIFICENT AGE OF ELEPHANTS.
THIS IS FROM THE RIGHT SIDE OF THE JAW.
FOSSILS ARE THE MESSENGERS OF THE PAST.
I BELIEVE THAT.
I THINK THAT WE, AS PALEONTOLOGISTS,
ARE TRYING TO BE THE INTERPRETERS
OF THE MESSENGERS FROM THE PAST.
THEY GIVE YOU THE OPPORTUNITY TO SEE
THE KIND OF INCREDIBLE JOURNEY
THAT ELEPHANTS HAD TO MAKE TO BECOME ELEPHANTS.
IT TOOK 60-MILLION YEARS TO MAKE AN ELEPHANT.
TODAY, BULUK IS ONE OF THE HOTTEST,
DRIEST PLACES ON EARTH.
BUT 17 MILLION YEARS AGO,
IT WAS A LUSH FOREST WITH RIVERS AND WETLANDS.
IT'S A VERY WET CLIMATE.
I'S A VERY EQUABLE CLIMATE, VERY WARM CLIMATE.
IT'S A GREAT PLACE TO BE A BROWSER.
IT'S A GREAT PLACE TO GO OUT AND LOOK FOR VEGETATION,
A GREAT PLACE TO GO GET A SALAD,
AFRICA IN THE EARLY MIOCENE.
HOW CAN SCIENTISTS RECONSTRUCT
THOSE VANISHED ENVIRONMENTS?
IT TURNS OUT ANCIENT LANDSCAPES LEAVE TRACES
JUST LIKE ANCIENT ANIMALS DO.
WE OFTEN FIND FOSSIL WOOD AND FOSSIL SEEDS,
SO THAT'S TELLING US SOMETHING ABOUT THE ENVIRONMENT
AND THE RED SEDIMENTS AROUND US ARE ANCIENT SOILS.
THEY'RE ACTUALLY ANCIENT FLOODPLAIN DEPOSITS.
SO THE ANIMALS WOULD HAVE BEEN LIVING
OUT ON THESE FLOOD PLAINS IN THESE FORESTED AREAS.
WE'RE TRYING TO RECONSTRUCT THE WHOLE ENVIRONMENT
THAT THESE ANIMALS WERE LIVING IN.
IF YOU GO IN AND JUST PICK UP THE BONES,
IT'S LIKE TAKING THE CHOCOLATE CHIPS OUT OF THE COOKIES.
SO WE WORK WITH GEOLOGISTS AND CLIMATE SCIENTISTS
AND ISOTOPE SPECIALISTS
AND ALL KINDS OF PEOPLE, GEO CHEMISTS.
THE PAINSTAKING WORK OF ELLEN AND HER COLLEAGUES
IS ALLOWING THEM TO RECONSTRUCT
THE WHOLE VANISHED WORLD OF ANCIENT BULUK.
SO IF YOU WERE TO BE TRANSPORTED BACK
TO THE EARLY MIOCENE OF BULUK, 17 MILLION YEARS AGO,
IT WOULD HAVE BEEN A MATURE MEANDERING RIVER SYSTEM
AND A WOODLANDS.
AND THERE WOULD HAVE BEEN A WHOLE HOST
OF DIFFERENT KINDS OF ELEPHANTS.
SO YOU WOULD HAVE HAD THE DEINOTHERES.
THEY'RE VERY, VERY PRIMITIVE.
THEY'RE ABOUT A THIRD OR A HALF
THE SIZE OF A MODERN ELEPHANT
AND THEY WOULD HAVE BEEN KIND OF SNUFFLING ALONG THE RIVER BANKS,
BECAUSE THEY SEEMED TO REALLY LIKE A CLOSED CANOPY FOREST
AND A WET ENVIRONMENT.
BUT AT THE SAME TIME, YOU HAVE THE AMEBELODONS,
THE SHOVEL TUSKERS.
THE LOWER INCISORS ARE THESE BIG LONG SHOVEL-LIKE TUSKS,
SO THEY WOULD HAVE USED THEM TO SCOOP UP THEIR DINNER.
AS SCIENTISTS EXCAVATE.
THEY ARE ASTONISHED BY THE DIVERSITY
OF STRANGE BEASTS THEY ARE DISCOVERING.
ANCIENT BULUK WAS A SORT OF JURASSIC PARK OF ELEPHANTS.
IMAGINE I'M TAKING YOU ON A SAFARI,
BUT A SAFARI BACK IN TIME.
YOU'LL BE CONFRONTED WITH THESE MAGICAL CREATURES,
A SLICE OF AFRICA THAT IS NOW GONE.
YOU'D BE CONFRONTED HERE WITH AMAZING HERDS OF ELEPHANTS.
IT WOULD BE MIND-BLOWING TO CONFRONT THIS SCENE.
I THINK THE MIOCENE 16 MILLION YEARS AGO AT BULUK,
THAT WOULD HAVE BEEN THE CENTER OF
THE EMPIRE OF THE AGE OF THE ELEPHANTS.
THE ANCIENT ELEPHANTS HERE BEAR WITNESS
TO A GLORIOUS FLOWERING OF THE ELEPHANT LINEAGE
ABOUT 17 MILLION YEARS AGO.
BUT WHAT WERE THEIR ORIGINS?
AND HOW DID THEY COME BY
THEIR MAGNIFICENT TUSKS AND TRUNKS?
FOR DECADES, THE EARLIEST ORIGINS
OF THE ELEPHANT LINEAGE WERE A MYSTERY.
BUT THEN IN THE 1990'S, A FRENCH PALEONTOLOGIST AND HIS TEAM
WERE EXCAVATING IN AN ABANDONED PHOSPHATE MINE IN MOROCCO.
IN LAYERS DATING TO 56 MILLION YEARS AGO,
HE CAME ACROSS FOSSIL REMAINS OF A MYSTERIOUS ANIMAL
ABOUT THE SIZE OF A SMALL DOG.
HE CALLED IT PHOSPHATHERIUM.
LATER HE CAME ACROSS FRAGMENTS OF THE JAWS AND TEETH
OF AN OLDER, EVEN SMALLER CREATURE.
THIS ONE WAS NO BIGGER THAN A RABBIT.
VOILA.
AS HE PUZZLED OVER BOTH FOSSILS,
HE NOTICED SOMETHING VERY STRANGE.
THEIR TEETH SEEMED TO BE
MINIATURE REPLICAS OF AN ELEPHANT'S TEETH.
THE MORE HE LOOKED THE MORE CERTAIN HE BECAME.
THEY MUST BE ANCESTRAL ELEPHANTS,
THE OLDEST EVER DISCOVERED.
IT WAS AN ASTONISHING CONCLUSION.
THE OLDEST ELEPHANT ANCESTOR WAS THE SIZE OF A RABBIT.
IT'S REALLY AMAZING.
THE FOSSILS WE FOUND
REVEAL THE ORIGINS OF PROBOSCIDEAN EVOLUTION.
WHICH USED TO BE TOTALLY UNKNOWN.
I GIVE A LOT OF CREDIT TO MY COLLEAGUE
EMMANUEL GHEERBRANT
BECAUSE IT'S LIKE A DETECTIVE STORY.
IT'S A REAL PUZZLER TO FIGURE OUT WHAT THEY ARE.
AND HE FOUND THESE THINGS
AND HE STARTED LOOKING AT THEIR TEETH
AND HE REALIZED THEY HAD
SOME SUBTLE FEATURES ON THEIR MOLARS,
THE ARRANGEMENT OF THE CUSPS ON THEIR MOLARS
THAT SAID I AM A PROBOSCIDEAN.
FINALLY, SCIENTISTS COULD SEE THE VERY BEGINNINGS
OF THE ELEPHANT EVOLUTIONARY TREE.
THE KEY TRAIT IS THE SLOW DEVELOPMENT
OF INCISORS AT THE FRONT OF THE SKULL.
THEY ARE ALREADY STARTING
TO BECOME ENLARGED IN PHOSPHATHERIUM.
THOSE INCISORS JUST KEEP GROWING
THROUGH ALL THE STAGES OF ELEPHANT EVOLUTION
RIGHT UP TO MAMMOTHS AND MODERN ELEPHANTS.
AS INCISORS BECAME TUSKS,
THEY TOOK ON THE FUNCTIONS THEY HAVE IN ELEPHANTS TODAY.
THEY'RE USED FOR ACQUIRING FOOD,
FOR KNOCKING DOWN PLANTS SO YOU CAN REACH FOOD.
THEY'RE USED FOR SOCIAL DISPLAY.
TUSKS ARE THE DEFINING FEATURES OF ELEPHANTS
AND IT'S LIKE THEIR BEHAVIOR
IS TIED UP IN HAVING THESE TUSKS.
AND AS TUSKS GREW,
THEY PROPELLED THE EVOLUTION OF THE TRUNKS
THAT WOULD BECOME THE HALLMARK OF ALL LATER ELEPHANTS.
SO I THINK ONCE YOU START TO GET TUSKS,
THEN TRUNKS FOLLOW THAT.
IT IS IMPORTANT,
BECAUSE THEY HAVE TO HAVE SOMETHING TO GET PAST THE TUSKS
IN ORDER TO REACH THE FOOD IN THEIR ENVIRONMENT.
AS TRUNKS GREW, THEY SLOWLY BECAME
THE AMAZINGLY SENSITIVE ORGAN OF TOUCH AND SMELL
THEY ARE IN MODERN ELEPHANTS.
TRUNKS ARE MADE UP OF SOMETHING LIKE
72,000 TINY MUSCLE FIBERS.
SO THEY'RE HIGHLY COMPLEX,
AND THEY CAN MOVE THEM AROUND
THE WAY THAT YOU CAN MOVE YOUR HAND AROUND
PLAYING THE PIANO.
ELEPHANTS HAVE TREMENDOUS CONTROL OVER THEIR TRUNK.
IT'S NOT JUST FLOPPING AROUND AND SUCKING UP WATER.
THEY CAN REALLY BE VERY GENTLE.
THEY CAN PICK A PENNY UP OFF THE GROUND WITH THEIR TRUNK.
THOSE TRUNKS GET A BIG WORKOUT.
TUSKS, TRUNKS, AND GREAT SIZE
WERE OBVIOUSLY SUCCESSFUL ELEPHANT ADAPTATIONS
TO THEIR FOREST ENVIRONMENT.
BUT THEY DIDN'T JUST HELP ELEPHANTS
RESPOND TO THEIR ENVIRONMENT,
THEY GAVE THEM THE CAPACITY TO CHANGE IT TOO.
SO, I THINK OF ALL THE SPECIES THAT WE KNOW OF,
APART FROM HUMANS,
THE ONLY OTHER MAMMALS THAT WE KNOW
HAVE THE CAPACITY TO BE ABLE TO ALTER
THE NATURAL ECOSYSTEMS THEY LIVE IN,
IN A SHORT TIME IN A VERY BIG WAY, WOULD BE THE ELEPHANTS.
PROBOSCIDEANS ARE BIG ANIMALS
AND YOU CAN IMAGINE ANY BIG ANIMAL
GOING THROUGH A LANDSCAPE IS KNOCKING DOWN TREES,
MOVING VEGETATION OUT OF THE WAY, CREATING PATHS.
FOR THAT,
BILL BELIEVES WE HUMANS OWE THEM A DEBT OF GRATITUDE.
HE THINKS ELEPHANTS HELPED CREATE THE PERFECT CONDITIONS
FOR A CERTAIN GROUP OF APES MILLIONS OF YEARS LATER
TO COME DOWN OUT OF THE TREES
AND BEGIN TO EXPLORE THE SAVANNAS.
THOSE WERE OUR ANCESTORS, THE AUSTRALOPITHECINES.
THE FAMOUS EARLY HUMAN LUCY
WAS DISCOVERED NOT FAR FROM BULUK.
BILL IS CONVINCED THAT SHE
AND OUR OTHER EARLY HUMAN ANCESTORS
FLOURISHED IN A LANDSCAPE THAT HAD BEEN UNINTENTIONALLY
PREPARED FOR THEM BY ELEPHANTS.
THIS IDEA OF ELEPHANTS OPENING THINGS UP
AND CREATING THE CONDITIONS OF SUCCESS FOR EARLY HOMINIDS,
MIGHT NOT BE AN EXAGGERATION TO SAY THAT
WE MIGHT NOT BE HERE WITHOUT ELEPHANTS.
AND JUST LIKE OUR ANCESTORS,
ELEPHANTS DID NOT STAY PUT.
AFTER MILLIONS OF YEARS IN AFRICA, THEY STARTED TO LEAVE.
PROBOSCIDEANS LEAVE AFRICA MULTIPLE TIMES.
DIFFERENT GROUPS LEAVE AT DIFFERENT TIMES.
THE FIRST MAJOR FORAY OUT OF AFRICA
IS AROUND 18 MILLION YEARS
AND THEY MAKE IT ALL THE WAY TO JAPAN
WITHIN A PERIOD OF ABOUT A MILLION YEARS
AFTER GETTING OUT OF AFRICA.
UNTIL RECENTLY, ALL WE KNEW
OF THOSE ANCIENT ELEPHANT SPECIES THAT LEFT AFRICA
WAS FROM A FEW FOSSIL BONES.
BUT THEN, A DRAMATICALLY DIFFERENT KIND OF DISCOVERY
BROUGHT THEM TO LIFE.
IN THE DESERTS OF ABU DHABI,
SCIENTISTS DISCOVERED NOT BONES BUT FOOTPRINTS.
THEY WERE MADE BY ANCIENT ELEPHANTS.
A VIVID RECORD OF THEIR GREAT MIGRATION OUT OF AFRICA.
IT'S PHENOMENAL
BECAUSE WHEN YOU'RE ACTUALLY ON THE LANDSCAPE,
IT SEEMS LIKE THE ELEPHANTS JUST PASSED THERE YESTERDAY,
BUT WE KNOW GEOLOGICALLY SPEAKING THAT'S IPOSSIBLE.
THESE ARE VERY, VERY OLD SEDIMENTS.
SO, IT WAS ALMOST AN AFTERTHOUGHT
TO IMAGE THE TRACKS FROM THE AIR.
AND THEN WE WENT BACK TO THE HOTEL THAT NIGHT
AND WE STARTED TO PUT THE IMAGERY TOGETHER.
AS WE REALIZED WHAT WE HAD WE BASICALLY OUR JAWS DROPPED.
WHAT THEY SAW WAS THE FOOTPRINTS
OF AN ENTIRE HERD OF ANCIENT ELEPHANTS ON THE MOVE,
A SNAPSHOT IN TIME OF ELEPHANT BEHAVIOR
SEVEN MILLION YEARS AGO.
BACK THEN THIS DESERT WAS A LUSH SAVANNA.
THE MUDDY GROUND AFTER A RAINFALL
CAPTURED THEIR FOOTPRINTS PERFECTLY,
ALL MADE BY ONE OF THE STRANGEST OF ELEPHANT RELATIVES.
IT'S PROBABLY 10 MINUTES
IN THE LIVES OF THESE INDIVIDUALS,
THIS HERD THAT WALKED ACROSS THE LANDSCAPE.
AND THOSE TEN MINUTES ARE FOREVER PRESERVED
IN THESE ROCKS FOR US TO SEE.
AND IN THAT 10-MINUTE SNAPSHOT,
FAYSAL CAN SEE ALL THE DYNAMICS OF THE HERD,
THE ADULTS AND CALVES, A SINGLE BULL MALE,
AND A NUMBER OF FEMALES.
YEAH, SO WE HAVE,
IT'S A MINIMUM OF 13 INDIVIDUALS ACTUALLY.
YOU'RE WALKING ALONG AND HERE WAS A LARGE INDIVIDUAL,
THERE WAS PROBABLY THE MATRIARCH.
THEY SLOW DOWN, THEY SPEED UP A LITTLE.
THERE WAS A SMALLER GUY.
HE'S ON THE EDGE SO WE'RE CLEARLY NOT TOO WORRIED
ABOUT ANY PREDATORS COMING ALONG ON THIS LANDSCAPE.
AND THEN, PERHAPS, JUST THE DAY BEFORE OR THE DAY AFTER,
WE'VE HAD THE LARGE BULL WHO ALSO CROSSED THIS LANDSCAPE.
NOT LONG AFTER FAYSAL
AND HIS TEAM MADE THEIR DISCOVERY,
THEY TOOK BILL SANDERS TO SEE IT.
I HAD NO IDEA WHAT AWAITED ME,
AND THEN I SAW THEM,
ALL THE FOOTPRINTS OF AN ENTIRE HEARD
GOING ON FOR ABOUT 260 METERS.
AND YOU CAN SEE BABY FOOTPRINTS, JUVENILE FOOTPRINTS,
FEMALE FOOTPRINTS,
AND THEN ONE GREAT TRACK OF A BIG BULL MALE
THAT MUST HAVE COME ALONG LATER AND CROSSED THAT TRACK
AND SORT OF CHECKING OUT THE HERD.
WE RARELY GET THAT OPPORTUNITY.
I WORK ON ELEPHANTS, I LOVE ELEPHANTS,
AND I'M SEEING THEIR BEHAVIOR CRYSTALIZED IN TIME,
ALL THE WAY BACK TO THE VERY BEGINNINGS OF ELEPHANTS.
AND I JUST STARTED CRYING.
AND MY COLLEAGUES ALL SORT OF APPLAUDED
AND THEY REALIZED I WAS NOT CRYING OUT OF SADNESS.
I WAS CRYING BECAUSE I WAS ECSTATIC.
LIKE SKILLED TRACKERS,
THE SCIENTISTS COULD READ THE ANCIENT FOOTPRINTS
AND RECONSTRUCT A REMARKABLY DETAILED PICTURE
OF THAT DAY SEVEN MILLION YEARS AGO.
WE COULD ESTIMATE THE ACTUAL SIZE
OF THESE INDIVIDUALS,
BASED ON STRIDE LENGTHS OF MODERN ELEPHANTS,
WHERE THEIR WEIGHTS ARE KNOWN,
AND THEIR STRIDE LENGTHS ARE KNOWN.
AND THEIR ESTIMATED WEIGHTS GO FROM,
A FEW HUNDRED KILOS FOR THE SMALL ONE,
UP TO 5,000 KILOS OR SO FOR THE LARGEST IN THE GROUP
AND POSSIBLY 6,000 OR SO FOR THE SOLITARY INDIVIDUAL
THAT WAS WALKING AT THAT SITE.
THAT MAKES THEM AS BIG AS ANY BULL ELEPHANT TODAY.
FROM FOSSILS FOUND NEARBY,
WE KNOW THAT THEY WERE MAGNIFICENT ANIMALS,
FOUR-TUSKED BEASTS CALLED STEGOTETREBELODONS.
AND HERE YOU ARE, YOU'RE ON THIS LANDSCAPE
AND YOU CAN IMAGINE THEM HAVING JUST BEEN HERE,
LIKE IT WAS YESTERDAY.
OVER GENERATIONS,
THEIR ANCESTORS MADE THE JOURNEY FROM AFRICA,
THOUSANDS OF MILES AWAY.
THEY'RE EXTINCT, THEY'RE LONG GONE,
AND THEY HAVEN'T JUST LEFT US THEIR BONES AND TEETH.
THIS IS AN IMPRINT OF THEIR SOCIETY.
THE DISCOVERIES IN ABU DHABI SHOW
THAT BY SEVEN MILLION YEARS AGO,
THE SOCIAL BEHAVIOR OF ELEPHANTS HAD ALREADY EVOLVED.
THEIR CLOSE FAMILY BONDS HAVE BEEN A KEY
TO THE SUCCESS OF ELEPHANTS FOR GENERATIONS.
EVEN THOUGH STEGOTETREBELODONS
DISAPPEARED A FEW MILLION YEARS AGO,
THEIR DESCENDENTS AND OTHER ELEPHANT SPECIES
SOON POPULATED MUCH OF THE GLOBE.
SOME, LIKE THE MAMMOTHS,
ADAPTED TO THE COLD OF SIBERIA AND NORTH AMERICA.
OTHERS, LIKE THE GOMPHOTHERES,
HEADED FOR THE WARMER CLIMES OF SOUTHERN ASIA
AND CENTRAL AMERICA.
IT HAD TAKEN 60 MILLION YEARS
BUT THE ELEPHANT LINEAGE HAD BECOME
ONE OF THE MOST SUCCESSFUL ON THE PLANET.
JUST 50,000 YEARS AGO,
ELEPHANT SPECIES WERE ON ALL CONTINENTS
EXCEPT AUSTRALIA, ANTARCTICA, AND SOUTH AMERICA.
SO, WHAT HAPPENED TO THEM ALL?
A LONG DEBATE AMONG MY COLLEAGUES IN MY FIELD HAS BEEN,
WHAT ARE THE AGENCIES
FOR THE EXTINCTION OF THE ELEPHANTS THAT WE SEE,
FOR EXAMPLE MAMMOTHS AND MASTODONS?
ONE HYPOTHESIS IS CLIMATE CHANGE.
AT THE END OF THE LAST ICE AGE,
10,000 YEARS AGO, THE WORLD WARMED.
THE COLD-ADAPTED ELEPHANTS OF SIBERIA AND NORTH AMERICA
JUST COULDN'T DEAL WITH IT.
IN THE NORTHERN HEMISPHERE,
IN NORTHERN LATITUDES,
YOU HAVE ALL THIS GLACIATION
AND THESE CHANGES ARE HAPPENING VERY, VERY RAPIDLY.
BUT FOR MILLIONS OF YEARS,
THE MAMMOTHS AND MASTODONS
MANAGED TO WEATHER SIMILAR CLIMATE CHANGES.
WHAT WAS DIFFERENT ABOUT THE WARMING
AT THE END OF THE LAST ICE AGE?
BILL BELIEVES IT WAS OUR OWN ANCESTORS
WHO TIPPED THE BALANCE.
SO WE SEE THE GREAT SITES IN EURASIA
WHERE INDIGENOUS PEOPLES LIKE 10,000 YEARS AGO
AND 50,000 YEARS AGO AND 60,000 YEARS AGO
WERE SLAUGHTERING THESE ELEPHANTS IN GREAT NUMBERS.
THERE IS A TREMENDOUS PREDATION PRESSURE.
AND IMAGINE IF YOU'VE GOT PREDATION PRESSURE
HITTING YOU ON ONE SIDE
AND NOW YOU'VE GOT THIS CLIMATE CHANGE,
AND WHAT IT DOES TO THE LANDSCAPE,
WHAT IT DOES TO THE PLANTS AND THE AVAILABLE RESOURCES.
BY 4,000 YEARS AGO,
THE WORLD WAS LEFT WITH JUST THE AFRICAN, ASIAN,
AND FOREST ELEPHANTS WE KNOW TODAY.
AND NOW THESE ARE UNDER THREAT AS WELL.
THIS TIME IT HAS NOTHING TO DO WITH THE END OF AN ICE AGE,
JUST US.
IN 1800, THERE WERE AN ESTIMATED 25 MILLION ELEPHANTS.
TODAY THERE ARE LESS THAN A MILLION
AND THE NUMBER IS FALLING FAST,
THANKS TO HABITAT LOSS
AND THE RELENTLESS SLAUGHTER OF ELEPHANTS FOR IVORY.
POACHING NOW IS VERY MECHANIZED, IT'S INDUSTRIAL.
IN SOME PLACES, WE'RE LOSING 1,000 ELEPHANTS IN A MONTH.
IT'S BEING DONE WITH NOT JUST WEAPONS,
BUT WITH AIRCRAFT, TRAINS, AND TRUCKS, AND SHIPS
TO MOVE THE IVORY OUT OF AFRICAN VERY QUICKLY.
THE TUSKS THAT HELPED ELEPHANTS SURVIVE
FOR MILLIONS OF YEARS HAVE BECOME A LIABILITY.
IT'S A NEW KIND OF EVOLUTIONARY PRESSURE, HUMAN GENERATED.
AND IN AFRICA, IT'S CAUSING ELEPHANTS
TO CHANGE ALMOST OVERNIGHT.
OVER THE MILLENNIA, ELEPHANTS HAVE EVOLVED
TO HAVE THESE HUGE TUSKS,
BECAUSE THE MOST SUCCESSFUL ELEPHANTS
ARE THE ONES THAT HAD THE BIGGEST TUSKS.
BUT OVER THE LAST FEW HUNDRED YEARS,
US HUMAN BEINGS HAVE BEEN KILLING ELEPHANTS
FOR THOSE TUSKS.
THERE ARE SOME POPULATIONS OF ELEPHANTS
WHO HAVE VERY SMALL TUSKS,
BECAUSE POACHERS ARE SELECTIVELY REMOVING
ELEPHANTS WITH BIG TUSKS.
AND SO, THE ONLY FEMALES THAT GET TO BREED
ARE THE ONES WHICH HAVE VERY SMALL TUSKS.
AND SO YOU INCREASINGLY SEE TUSKLESSNESS
IN SOME OF THESE ELEPHANT POPULATIONS.
IT WOULD BE SUCH A TRAGEDY IF THESE MAGNIFICENT ANIMALS
LOST THE ONE THING THAT MAKES THEM,
YOU KNOW, SO UNIQUE, THEIR TUSKS.
EVEN AS THEY ADAPT, ELEPHANTS ARE AT RISK.
LIKE SO MANY OTHER CREATURES,
THEY NOW FACE A NEW ERA OF EXTINCTION.
EVERYWHERE THE NATURAL WORLD IS BEING TRANSFORMED.
OUR OWN LINEAGE HAS BECOME
THE PLANET'S DOMINANT EVOLUTIONARY FORCE,
SHAPING THE WEB OF LIFE THAT EXISTS ALL AROUND US.
THIS ONE RECENTLY ARRIVED SPECIES
IS NOW THE WORLDWIDE PRESENCE
TO WHICH ALL OTHERS MUST ADAPT.
OUR IMPACT IS SO HUGE
THAT OUR ERA HAS BEEN GIVEN ITS OWN NAME,
THE ANTHROPOCENE, THE AGE OF HUMANS.
IT HAS SEEN THE EXTINCTION RATE AMONG NATURAL SPECIES SOAR
TO HUNDREDS OF TIMES WHAT IT WAS BEFORE OUR ARRIVAL.
AS SCIENTISTS RACE TO CHART THE PLANETARY CHANGES,
THEY CAN LOOK BACK AT LESSONS FROM DEEP TIME.
THEY'RE OBSERVING MANY OF THE THINGS
THAT HAPPENED IN EARLIER EXTINCTIONS,
RISING CO2 LEVELS LEADING TO ACIDIFICATION OF THE OCEANS
AND RAPID CLIMATE CHANGE,
HABITAT DESTRUCTION.
MANY BELIEVE WE ARE WITNESSING
OUR PLANET'S SIXTH MASS EXTINCTION,
BUT THE FIRST ONE CAUSED BY A SINGLE SPECIES.
LIKE OTHERS, IT WILL RESET THE EVOLUTIONARY CLOCK.
WE JUST DON'T KNOW HOW.
TODAY WHEN WE LIVE IN A WORLD WHERE HUMAN POPULATIONS
ARE GRADUALLY CHANGING THE FACE OF THE GLOBE
BY TURNING NATURAL ENVIRONMENTS
INTO ARTIFICIAL ENVIRONMENTS,
BY POLLUTION AND MANY OTHER WAYS
OF INTERFERING WITH NATURAL SYSTEMS,
WE ARE VERY MUCH CONFRONTED
WITH THE QUESTION OF EVOLUTION AND EXTINCTION.
YOU CAN'T HAVE EVOLUTION WITHOUT EXTINCTION,
BUT EXTINCTION REALLY COMPLICATES
OUR EFFORTS TO GET THE BIG PICTURE.
WE NOW KNOW THAT MASS EXTINCTIONS
ARE AN ENGINE OF EVOLUTION,
CLEARING OUT ENVIRONMENTS,
MAKING ROOM FOR NEW SPECIES TO EVOLVE,
BUT IN THE PAST, THEY HAVE USUALLY TAKEN MILLIONS OF YEARS.
THIS ONE IS HAPPENING FAST, IN A MATTER OF GENERATIONS.
VIEWED THROUGH THE LENS OF DEEP TIME,
THAT IS A NANOSECOND,
TOO FAST FOR MANY LIVING THINGS TO ADAPT.
BUT MAYBE NOT TOO FAST FOR US TO MAKE A DIFFERENCE.
CROCS HAVE LIVED ON EARTH FOR ALMOST 230 MILLION YEARS.
THEY'VE SURVIVED CATACLYSMIC EXTINCTION EVENTS,
BUT TODAY,
FIVE OF THE 14 CROCODILE SPECIES ARE CRITICALLY ENDANGERED.
MOST OF THE LIVING CROCODILIANS
WERE ON THE VERGE OF EXTINCTION BY THE 1970'S.
WE WERE ON THE VERGE OF LOSING ALL OF THEM
WHEN WE PUT IN PLACE PROTECTION.
PROTECTIONS HAVE HELPED.
IN AUSTRALIA, BOTH FRESH AND SALTWATER CROCS HAVE REBOUNDED
THANKS TO STRONG STEPS LIKE RESTRICTIONS ON HUNTING.
BUT WHAT ABOUT THE OTHER GREAT SURVIVORS OF DEEP HISTORY?
10,000 SPECIES OF BIRD STILL COVER THE GLOBE.
SOME HAVE ADAPTED TO CITIES
WHERE THEY LIVE BESIDE US IN SEEMING HARMONY.
BUT THAT'S NOT THE WHOLE STORY.
WE ARE HUGELY IMPACTING BIRD EVOLUTION.
THIS IS IN HABITAT LOSS, CONSUMPTION OR KILLING,
POISONS, THE USE OF TOXINS IN OUR ENVIRONMENT.
WITH 40 PERCENT OF BIRD SPECIES IN DECLINE,
THERE'S REASON TO WORRY,
BUT ALSO REASON TO HOPE.
WE MANAGED TO TURN THINGS AROUND FOR ICONIC SPECIES
LIKE THE BALD EAGLE AND CALIFORNIA CONDOR.
AND INNOVATIVE PROGRAMS SHOW THAT MORE IS POSSIBLE.
IN 1974 ONLY FOUR MAURITIUS KESTRELS WERE LEFT IN THE WILD.
TODAY THERE ARE A HUNDRED TIMES AS MANY,
THANKS TO PREDATOR CONTROL AND CAPTIVE BREEDING.
OCEAN CREATURES NEED PROTECTION TOO.
IT TOOK 50 MILLION YEARS FOR WHALES TO BECOME
THE WONDROUS GIANTS OF THE DEEP WE KNOW TODAY.
BUT IN JUST TWO CENTURIES,
INDUSTRIAL WHALING BROUGHT MANY OF THEM
TO THE BRINK OF EXTINCTION.
IN THE 20TH CENTURY ALONE,
ALMOST THREE MILLION WHALES WERE SLAUGHTERED
IT'S UNTHINKABLE NOW,
THAT WE EXPLOITED WHALES TO THE EXTENT OF,
IN THE CASE OF HUMPBACKS, DRIVING DOWN THEIR POPULATION
TO 10 PERCENT OF WHAT THEY WERE GLOBALLY.
THEY WERE ALMOST PUSHED OVER THE EDGE.
WE ONLY STOPPED WHALING
ON NORTHERN VANCOUVER ISLAND IN 1967.
HUMPBACKS WE STOPPED IN 1965.
SO WE THOUGHT OF THEM SO VERY DIFFERENTLY.
WE SAW THEM AS A RESOURCE.
BUT WITH HUMPBACKS WE HAVE A SECOND CHANCE.
WHILE SOME WHALES ARE CRITICALLY ENDANGERED,
WHALING BANS HAVE MADE A DIFFERENCE.
HUMPBACKS HAVE REBOUNDED,
AND BLUE WHALE POPULATIONS, WHICH FELL TO JUST 1,500,
SEEM TO BE SLOWLY INCREASING.
ONE OF THE MANY THINGS THAT THE WHALES DO
IS THEY REMIND US HOW CONNECTED WE ARE,
AND OF OUR CAPACITY FOR CHANGE.
AROUND THE PLANET,
OTHERS ARE HEEDING THAT REMINDER,
COMMITTING THEMSELVES
TO PROTECT ENDANGERED ANIMALS AND PLACES.
IN KENYA, PAULA KAHUMBU ADMIRES
ONE OF THE LAST TRUE GIANTS LEFT ON EARTH,
A TUSKER NAMED TOLSTOY.
I FEEL VERY HUMBLED TO BE ABLE TO MEET TOLSTOY.
HE IS A GIANT OF GIANTS.
HE'S NOT JUST A BIG TUSKER, HE'S A SUPER TUSKER.
THERE ARE VERY, VERY FEW ELEPHANTS OF THAT SIZE
WITH TUSKS OF THAT LENGTH LEFT IN THE WORLD.
YOU KNOW, WHEN WHEN YOU'RE WITH TOLSTOY,
IT'S ONE OF THE BIGGEST RUSHES YOU GET IS THAT I'M ALIVE.
RIGHT, YOU JUST FEEL THIS SENSE OF LIFE.
IT GIVES YOU GOOSEBUMPS JUST TO KNOW
THAT THIS ELEPHANT IS AWARE OF YOUR PRESENCE,
AND YOU'RE TINY AND HE'S HUGE.
IT'S, HE'S BEAUTIFUL.
IT'S A JUST A MOST INCREDIBLE EXPERIENCE.
TO KNOW THAT TOLSTOY,
IS THE PRODUCT OF AN EVOLUTIONARY JOURNEY
THAT HAS BEEN GOING ON FOR EONS
ONLY MAKES HIM MORE PRECIOUS.
AND TOLSTOY IS NOT ALONE.
CROCODILES AND BIRDS, WHALES AND ELEPHANTS
ARE JUST FOUR LIFE FORMS AMONG MILLIONS.
THE TREE OF LIFE IS VAST,
ENCOMPASSING EVERYTHING THAT HAS EVER LIVED.
WHAT WILL ITS BRANCHES LOOK LIKE AFTER THE AGE OF HUMANS?
THE ANSWER IS UP TO US.