Mysteries of Evolution

WHY DOES THE GIRAFFE HAVE SUCH A LONG NECK?

WHY IS THE VULTURE'S HEAD BALD?

WHY MIGHT THE MANDRILL HAVE A MULTICOLORED FACE?

ORANGUTANS ARE CHEEKY PRIMATES, BUT WHY?

AND HOW COULD A FLATHEAD, LIKE THE HAMMERHEAD SHARKS,

BE AN ADVANTAGE?

ALL OF THESE CREATURES GET AHEAD WITH ADAPTATIONS

FROM THE NECK UP.

WHEN AN ANIMAL COMES FACE TO FACE WITH A VULTURE,

IT PROBABLY MEANS IT'S ALL OVER.

VULTURES MEET OTHER CREATURES AT THE END OF THE ROAD.

TOGETHER THEY CIRCLE A CARCASS AND THEN FEED ON THE CARRION

INGESTING BACTERIA THAT WOULD INFECT

AND KILL OTHER KINDS OF ANIMALS.

BUT HOW DO VULTURES EAT ROTTING MEAT

WITHOUT GETTING SICK?

WILD VULTURES ARE FOUND ON EVERY CONTINENT

EXCEPT ANTARCTICA AND AUSTRALIA.

THEY ARE DIVIDED INTO TWO GROUPS,

OLD WORLD AND NEW WORLD.

OLD AND NEW WORLD VULTURES ARE NOT AS CLOSELY RELATED

AS YOU'D THINK.

THEY ARE A PERFECT EXAMPLE OF CONVERGENT EVOLUTION,

SPECIES WHO INDEPENDENTLY EVOLVE SIMILAR TRAITS

AS A RESULT OF ADAPTING TO SIMILAR ENVIRONMENTS.

OLD WORLD VULTURES ARE RELATED TO HAWKS AND EAGLES.

NEW WORLD VULTURES ARE CLOSELY RELATED TO STORKS.

ONE EXTINCT SPECIES IN THEIR LINEAGE IS THE GIANT TERATORN,

A CONDOR-LIKE BIRD THAT LIVED IN ARGENTINA

FIVE TO EIGHT MILLION YEARS AGO.

TERATORNS ARE THE LARGEST SPECIES OF FLYING BIRD

EVER TO BE DISCOVERED, WEIGHING IN AT 170 POUNDS

WITH A WINGSPAN NEARLY THAT OF A SMALL AIRPLANE.

DUE TO THEIR MONSTROUS SIZE,

THESE BIRDS WOULD HAVE NEEDED THE HELP OF WIND

AND A STEEP SLOPE TO ACHIEVE FLIGHT.

IT'S THOUGHT THE TERATRONS ACTIVELY HUNTED THEIR PREY

VULTURES TODAY DO NOT.

THESE MEAT-LOVERS ARE NOT LIKE OTHER BIRDS OF PREY.

THEIR VIRTUE ISN'T VIOLENCE, IT'S PATIENCE.

VULTURES ARE UNIQUE

BECAUSE THEY DON'T TYPICALLY HUNT FOR THEIR FOOD

THE WAY WE THINK OF BIRDS OF PREY.

THEY DO NOT HAVE THE POWER TO TAKE A HEALTHY LIVE ANIMAL.

SO THEY ARE GONNA GO AFTER STUFF THAT'S DYING,

ON ITS WAY OUT OR DEAD.

THE VULTURES HAVE A DISTINCTIVE BALD HEAD.

IT'S AN ODD LOOK,

BUT ESSENTIAL FOR THE BIRD'S SURVIVAL.

WITHOUT FEATHERS

THERE'S NO PLACE FOR THE BACTERIA IN THE CARRION

TO SURVIVE AND INFECT THE BIRD.

IF YOU IMAGINE THAT YOUR FEEDING HABIT

IS TO DIG YOUR HEAD INTO A SACK OF ROTTING MEAT,

WELL, THEN IT WOULD BE ADVANTAGEOUS

NOT TO HAVE A HEAD FULL OF FEATHERS

FOR ALL OF THAT MEAT TO GET STUCK INTO.

SINCE THEIR ENTIRE EXISTENCE DEPENDS ON FINDING

THE DEAD AND DYING,

SPECIES LIKE THE TURKEY VULTURE

HAVE DEVELOPED ONE OF THE MOST IMPRESSIVE NOSES

IN THE ANIMAL KINGDOM.

THEY HAVE A VERY KEEN SENSE OF SMELL,

WHICH IS QUITE RARE AMONG BIRDS

AND THIS, AS WE CAN IMAGINE, IS ONE OF THE MEANS

BY WHICH THEY FIND THEIR FOOD BY HOVERING AROUND

AND BEING ABLE TO ESSENTIALLY TO SMELL THE PUTRID ODORS

THAT ARE EMANATING FROM A CARCASS

THAT'S ROTTING SOMEWHERE HIDDEN IN A VALLEY

OR ON THE GROUND SOMEWHERE.

THIS VULTURE CAN DETECT THE SCENT

OF ROTTING FLESH IN THE AIR

IN CONCENTRATIONS AS TINY AS A FEW PARTS PER BILLION.

THEY HAVE THESE REALLY BIG NOSTRILS,

IN FACT, SO BIG THAT MANY OF THEM

YOU CAN LOOK RIGHT THROUGH THEIR BEAK

AND SEE DAYLIGHT THROUGH THE OTHER SIDE.

AND SO THAT IS, OF COURSE, ALLOW THE GOOD INTAKE OF AIR

FOR THEM TO BE ABLE TO SMELL REALLY EFFECTIVELY,

BUT IT ALSO HAS THIS CONSEQUENCE OF MANY TIMES

GETTING THEIR NOSE STUFFED FULL OF ROTTING MEAT

AS THEY'RE FEEDING.

ONCE THIS ROTTING FLESH MAKES IT PAST THEIR NOSE,

IT THEN TRAVELS TO THEIR BELLY

AND SINCE CARRION IS INFECTED

WITH INCREDIBLY HARMFUL BACTERIA,

VULTURES HAVE AN ADAPTATION TO COMPENSATE.

THE INSIDES OF THEIR STOMACHS ARE COATED WITH ACID SO STRONG

IT'S CAPABLE OF DISSOLVING AN ALUMINUM CAN.

THEIR STOMACHS ARE 10 TO 100 TIMES MORE RESISTANT

TO THE EFFECTS OF ACID THEN A HUMAN'S.

BECAUSE THEY FEED ON ROTTING MEAT,

THEY ACTUALLY HAVE A DIGESTIVE SYSTEM

THAT COMPENSATES FOR THIS

BY HAVING HIGHLY CORROSIVE STOMACH ACIDS,

WHICH ARE ESSENTIALLY ABLE TO DECOMPOSE

AND ATTACK ALL OF THOSE PATHOGENS

THAT MIGHT CAUSE YOU OR I TO GET SICK

IF WE WERE TO EAT IT.

IF BACTERIA DO SURVIVE,

THEIR BLOOD IS PACKED WITH ANTIBODIES

READY TO ATTACK INVADING THREATS.

AS MESSY AND MEAN AS THEY SEEM,

VULTURES COMPLETE OUR FOOD CHAIN.

SEEMINGLY COOL, BUT ACTUALLY CRAFTY,

VULTURES HAVE EVOLVED TO FEED ON ROTTING CARCASS.

WITH BARE NECKS AND STRONG STOMACHS,

THESE CREATURES TAKE THEIR LIVES FROM DEATH ITSELF.

SLICING THROUGH THE OCEAN

IS ONE OF THE STRANGEST LOOKING HEADS

IN THE ANIMAL KINGDOM.

IT ALMOST LOOKS LIKE A MISTAKE,

BUT WHAT IS IT ABOUT THIS ODD BODY PART

THAT ACTUALLY HELPS THIS SPECIES SURVIVE?

SHARKS HAVE BEEN AROUND FOR 400 MILLION YEARS.

BUT THE SHARK FAMILY

THAT IS THOUGHT TO HAVE EVOLVED MOST RECENTLY

IS THAT OF THE HAMMERHEAD SHARKS

RADIATING INTO NINE DIFFERENT MODERN SPECIES.

SCIENTISTS BELIEVE THAT ALL HAMMERHEADS

DESCENDED FROM A COMMON ANCESTOR

THAT SWAM THE SEAS 20 MILLION YEARS AGO.

THIS SHARK LOOKS LIKE

IT'S HEAD GOT CAUGHT UNDER A STEAM ROLLER,

BUT IT'S THIS VERY TRAIT

THAT HAS INTRIGUED SCIENTISTS FOR YEARS

LEADING TO A NUMBER OF PLAUSIBLE THEORIES FOR THE SHAPE.

WE'RE STILL NOT SURE AS SCIENTISTS

EXACTLY WHY THIS HAPPENED IN TERMS OF EVOLVING SEPARATELY.

WE KNOW THERE'S A LOT OF BENEFITS.

SO THERE ARE A NUMBER OF THEORIES

AS TO WHAT ARE THE MAIN FUNCTIONS

AND THEN IN FACT, THEY'RE NOT MUTUALLY EXCLUSIVE

FROM ONE ANOTHER.

IT COULD HAVE SOMETHING TO DO BY INCREASING ITS FIELD OF VISION,

HAVING ITS EYE SEPARATED LIKE THAT

OVER A LONG, BROAD FACE.

ALTERNATIVELY, IT MAY ACTUALLY HAVE A HYDRODYNAMIC ROLE.

SO IT MAY ACTUALLY HELP IT SWIM MORE EFFECTIVELY

VERY MUCH LIKE A WING OF AN AIRPLANE CAUSES A LIFT.

LASTLY, OF COURSE,

WE CAN RECOGNIZE THAT PART OF THE HUNTING MECHANISM OF SHARKS

IS IN THE ELECTROMAGNETIC SENSORS

THAT THEY HAVE IN PITS ON THEIR FACES.

LITTLE ELECTRO-SENSORY ORGANS

THAT ALLOW THEM TO DETECT ELECTROMAGNETIC FIELDS

THAT ARE EMITTED BY ALL LIVING ORGANISMS.

AND SO THE IDEA IS RATHER THAN HAVE YOUR FACE

POINTED AS SUCH WITH A CERTAIN SURFACE AREA ON IT,

SPREAD THAT SURFACE AREA OVER A GREATER DISTANCE

AND HAVE IT ALL OUT FRONT.

THE SHAPE OF THEIR HEAD IS ALSO A DISTINCT ADVANTAGE

BECAUSE OF JUST HOW BIG IT IS.

THEIR HEAD IS PACKED WITH SENSORY ORGANS

TO PICK UP ALL SORTS OF CUES FROM POTENTIAL PREY ITEMS

DOWN TO THE ELECTRIC SIGNALS

THAT EMANATE FROM EVERY LIVING THING.

THEY HAVE SPECIAL ELECTRO-RECEPTORS

CALLED AMPULLAE OF LORENZINI

THAT ARE SPREAD OUT OVER THEIR MASSIVE HEADS.

SO PREY ITEMS CAN'T HIDE FOR LONG.

THE GREAT HAMMERHEAD SHARK'S FAVORITE FOOD

IS SOUTHERN STING RAYS OR ANY SPECIES OF STINGRAY.

OFTEN TIMES YOU'LL GET A STINGRAY

THAT'S EATING CLAMS ON THE BOTTOM,

THAT SENDS OUT SOUND WAVES, IT SENDS OUT VIBRATIONS.

IT ALSO SENDS OUT A SENT CUE.

THE HAMMERHEADS CAN PICK UP ON THAT.

ONCE THE STINGRAY HAS, KIND OF, BEEN IDENTIFIED

BY SCENT SOUND,

THEN THEY START USING THEIR AMPULLAE OF LORENZINI.

THEY'RE LOOKING WITH ELECTRIC CUES

WHERE THAT STINGRAY MIGHT BE BURIED IN THE SAND

AND THEN THEY PREY ON THAT ITEM.

HAVING THIS WIDE HEAD GIVES THEM A GREAT ADVANTAGE.

INSTEAD OF HAVING THEIR FACE COME TO A POINT,

THEY HAVE ALL THEIR SENSORY ORGANS

SPREAD OUT ON THIS BIG FLAT SURFACE.

IT'S LIKE THE HAMMERHEADS HAVE A WIDE BEAM OF HEADLIGHTS

HELPING THEM SCOUR THE SEA FLOOR.

SOME THINK THE HAMMER-SHAPED HEAD

GIVES THEM A HYDRODYNAMIC LIFT

HELPING THEM REACH SPEEDS OF UP TO 45 MILES AN HOUR.

IT'S ALL PART OF HOW THESE SHARKS HAVE EVOLVED

TO BE PERFECT PREDATORS.

ORANGUTANS MAY BE CLOSELY RELATED TO HUMANS,

BUT THEY ARE A LOT CHEEKIER THAN WE ARE.

WHAT IS THE PURPOSE OF THOSE AMAZING FLANGES?

IN THE ISLANDS OF BORNEO AND SUMATRA

LIVES A MOST-IMPRESSIVE GREAT APE.

THE LARGEST TREE-CLIMBING ANIMAL IN THE WORLD,

THE WILD ORANGUTAN IS OUR VERY CLOSE COUSIN.

THEY SHARE ABOUT 96% OF THE SAME GENES AS HUMANS,

YET LOOK AND BEHAVE SOMEWHAT DIFFERENTLY.

THEIR STORY BEGINS IN THE TREES.

IT TURNS OUT THAT THE STORY THAT WE KNOW

ABOUT WHERE THE PRIMATES CAME FROM

IS THAT THEY WERE SPECIES

THAT FIRST EVOLVED ABOUT THE SAME TIME

THAT FLOWERING PLANTS EVOLVED.