15,000 YEARS AGO, AFTER THE LAST GREAT ICE AGE ENDED AND MAN FIRST BEGAN TO LIVE IN PERMANENT SETTLEMENTS, ANOTHER SPECIES WAS WATCHING CLOSELY FROM THE FOREST.

AND THEY SAW US AS A ONCE-IN-A-LIFETIME OPPORTUNITY.

WITHIN JUST A FEW HUNDRED YEARS, THESE WOLVES CHANGED FROM DEADLY PREDATORS INTO MAN'S BEST FRIEND.

CANIS LUPUS FAMILIARIS, THE VERY FIRST DOGS.

THIS TRANSFORMATION FROM WILD WOLF TO TAME DOG PROVED REVOLUTIONARY TO MAN.

DOGS BECAME OUR HUNTING PARTNERS, PROTECTORS OF OUR SETTLEMENTS AND OUR LIVESTOCK.

WHEREVER WE VENTURED IN THE WORLD, WE TOOK THEM WITH US.

BUT AFTER THOUSANDS OF YEARS OF WORKING TOGETHER, WE DISCOVERED SOMETHING COMPLETELY NEW ABOUT THE DOG.

THIS ANIMAL IS AN EVOLUTIONARY MIRACLE.

IN THE SPACE OF 150 YEARS, IT HAS BECOME THE MOST VARIED SPECIES ON THE PLANET.

[ DOG BARKS ] FIERCE, FRIENDLY, HAIRY, BALD, CUTE, WRINKLED, MASSIVE, TINY.

WITH OVER 400 INTERNATIONALLY RECOGNIZED BREEDS, THE DOG HAS A GREATER RANGE OF SHAPES AND SIZES THAN ANY OTHER MAMMAL.

SOME OF THESE DOGS ARE BEING TRAINED TO HUNT THE KILLERS OF THE FUTURE.

SOME OF THESE DOGS FACE PROBLEMS AND THEIR VERY SURVIVAL IS IN QUESTION.

THIS IS THE STORY OF HOW A CHINESE EMPRESS AND A VICTORIAN PASSION CREATED THE MOST VARIED MAMMAL ON EARTH.

IT'S ALSO THE STORY OF HOW OUR CHOICES WILL DETERMINE THE DOG'S FUTURE.

PROFESSOR OF BIOLOGY RAYMOND COPPINGER IS ABOUT TO SHOW US HOW THE WOLF WAS ABLE TO TURN INTO 400 BREEDS OF DOG.

[ IMITATING BARKING ] Abraham: AS HIS SIMPLE EXPERIMENT WILL PROVE, IT'S ALL ABOUT HUMAN CHOICES.

Coppinger: CAN YOU HELP ME WITH AN EXPERIMENT, SIR?

YES, SIR.

TELL ME.

WHAT I WANT YOU TO DO IS, I WANT YOU TO LOOK AT THESE PUPPIES, AND I WANT YOU TO PICK YOUR FAVORITE ONE.

MY FAVORITE ONE?

YEAH, WHICH ONE IS YOUR FAVORITE DOG?

WHY DO YOU LIKE THAT ONE?

Man: BECAUSE THAT'S DIFFERENT.

IT'S ORIGINAL, IT'S DIFFERENT FROM THE REST.

Abraham: IN THIS PARK IN MEXICO CITY, THE PROCESS THAT MOLDED THE FIRST PRIMITIVE DOGS INTO SO MANY DIFFERENT FORMS STILL HAPPENS TODAY.

WOW.

NOW, WHY DID YOU PICK THAT ONE?

IT'S BEAUTIFUL.

IT HAS VERY STRANGE EYES.

I LIKE THIS FACE -- WELL, I LIKE THEM ALL, AND THE BLACK ONE IS BEAUTIFUL, BUT THIS... WELL, I THINK THIS ONE.

THAT ONE THERE?

WHY DO YOU LIKE THAT ONE?

BECAUSE HE SHOWS MORE INTEREST.

I SEE.

LIKE, HE'S MORE CURIOUS.

SO HE'S PROBABLY GOING TO BE, LIKE, MORE, HE'S GOING TO DEVELOP MORE... MORE COMMON SENSE.

WHY DID YOU PICK THE BLACK ONE?

BECAUSE, I DON'T KNOW, IT IS SIMILAR TO MY SOUL.

[ KISSES ] Coppinger: WE JUST DID THIS LITTLE EXPERIMENT, AND IT'S AN IMPORTANT LITTLE EXPERIMENT, BECAUSE, RATHER THAN PICK THE AVERAGE ONE, IT'S A KIND OF A HUMAN RESPONSE TO PICK ONE OF THE EXTREMES.

IN THE LONG HAUL, WHAT THAT MEANS IS THAT YOU'RE INCREASING THE AMOUNT OF VARIATION THAT YOU ARE GETTING, BECAUSE YOU ARE PICKING THE EXTREMES OF THE LITTER, SO THEN YOU ARE BREEDING THEM BACK TO OTHER EXTREMES OF THE LITTERS AND SO YOU KIND OF JUST FAVOR THIS ENDLESS VARIATION THAT GOES ON AND ON AND ON.

Abraham: PEOPLE DISCOVERED THAT BY BREEDING TOGETHER THE DOGS WITH TRAITS AND CHARACTERISTICS THEY LIKED BEST, THESE WOULD BE PRESERVED AND EVEN EXAGGERATED IN THE NEXT GENERATION.

BUT, AS WE HAVE SEEN, THE REASONS WE CHOOSE A PARTICULAR DOG DEPEND VERY MUCH ON WHO WE ARE.

NEARLY 8,000 MILES AWAY, THIS IS THE ARRISHEH DESERT IN JORDAN.

TEMPERATURES HERE CAN REACH OVER 120 DEGREES FAHRENHEIT.

IN ONE OF THE HARSHEST ENVIRONMENTS ON EARTH, WHERE ONLY THE VERY TOUGHEST OF SPECIES SURVIVE, MAN AND DOG MAKE A FORMIDABLE TEAM.

FOR 6,000 YEARS, THE BEDOUIN HAVE CONSISTENTLY BRED FROM ONLY THE QUICKEST, MOST LONG-LEGGED AND AGILE DOGS WITH THE BEST EYESIGHT.

THESE CHOICES HAVE CREATED ONE OF THE MOST SPECTACULAR DOGS KNOWN TO MAN.

THE SALUKI CAN OUTRUN ALMOST ANYTHING THAT MOVES ON THE HORIZON AND SECURE NUTRITIOUS MEAT FOR ITS MASTERS.

THEIR STAMINA AND STRENGTH ARE BREATHTAKING.

THE SALUKI HELPED TURN THE HOSTILE DESERT INTO A HOME FOR ALI'S BEDOUIN ANCESTORS, WHO TREATED IT AS A GIFT FROM GOD.

[ SPEAKING BEDOUIN LANGUAGE ] Interpreter: WHAT MAKES THEM SO SPECIAL IS THE SHAPE OF THE DOG, THE LONG LEGS.

THEY CAN RUN QUICKER THAN THE OTHER DOGS, WHICH IS VERY IMPORTANT FOR THE HUNTING.

WHEN THE SALUKI KNOWS IT'S GOING OUT HUNTING, IT IS VERY EXCITED, BECAUSE IT KNOWS IT'S GOING OUT TO RUN AND CATCH THE HARE.

IT'S READY FOR IT AND ENJOYS IT VERY MUCH.

Abraham: HUSSEN IS JUST 12.

HIS UNCLES ARE TAKING HIM ON HIS FIRST SALUKI HUNTING TRIP, TEACHING HIM THE SKILLS THAT THE BEDOUIN HAVE PASSED DOWN THROUGH COUNTLESS GENERATIONS.

THERE IS LITTLE COVER, AND ANY CREATURE WILL SEE THEM APPROACHING FROM MILES AWAY.

THE ONLY WAY TO CATCH A HARE IS TO OUTRUN IT.

[ MAN CALLING IN BEDOUIN LANGUAGE ] IT IS THE PHENOMENAL SPEED OF THE SALUKI, CREATED BY SIMPLE HUMAN CHOICES, THAT IS THE KEY TO ITS SUCCESS.

THEY ARE THE ORIGINAL SPEED DEMONS, PRECURSORS OF THE GREYHOUND, PERFECTLY SUITED FOR THE DESERT.

IF WE LOOK UNDER THE SALUKI'S SKIN, WE CAN SEE HOW CAREFUL BREEDING HAS TRANSFORMED THE PRIMITIVE EARLY DOG INTO THE ULTIMATE SPRINTER AND THE BEDOUIN'S DEADLY WEAPON.

THE SALUKI HAS BECOME HIGHLY STREAMLINED.

ITS BONES ARE LIGHT, AND ITS RIB CAGE AND WAIST INCREDIBLY SLENDER.

SALUKI DOGS HAVE A UNIQUELY FLEXIBLE SPINE, SIMILAR IN DESIGN TO A CHEETAH, WHICH ALLOWS THEM TO TURN ON A DIME IN PURSUIT OF PREY.

THE STRIDE IS HUGE.

AT TOP SPEED, IT FLIES 12 FEET ACROSS THE GROUND.

THE HEART CAN BE UP TO A THIRD LARGER THAN OTHER DOGS', WITH A SUPER-SIZED AORTA PROPELLING BLOOD TO ITS MUSCLES FAST, GIVING THE DOG THE POWER TO REACH FULL STRIDE VERY QUICKLY.

THEY ARE SIGHT HOUNDS.

AND ONCE THEY'VE SPOTTED THEIR PREY, IT STANDS LITTLE CHANCE OF ESCAPE.

[ MAN CALLING IN BEDOUIN LANGUAGE ] WHAT HAPPENS NEXT IS TRULY INCREDIBLE.

THE BEDOUIN TRAINING HAS ALTERED THE SALUKI'S NATURAL INSTINCT TO KILL.

INSTEAD, IT CATCHES AND HOLDS THE PREY FOR ITS MASTER.

[ CALLING IN BEDOUIN LANGUAGE ] Abraham: TODAY, THE BEDOUIN NO LONGER RELY ON THE SALUKI TO CATCH ALL OF THEIR MEAT.

BUT IN THE PAST, HUSSEN'S ANCESTORS WOULD HAVE DEPENDED ON THEM FOR THEIR VERY SURVIVAL.

THE BOND THAT STILL EXISTS BETWEEN ALI, HUSSEN, AND THEIR DOGS IS SPECIAL -- BUT NOT UNIQUE.

FROM HAULING AND HERDING... TO RUNNING FAST AND TRACKING, ON EVERY CONTINENT, FROM THE DESERT TO THE ARCTIC, THERE ARE PEOPLE WORKING WITH AND DEPENDING ON THEIR DOGS EVERY DAY.

OUR PUPPY EXPERIMENT IN MEXICO SHOWED US HOW PEOPLE INVARIABLY CHOOSE DIFFERENT PUPPIES FOR DIFFERENT REASONS.

THE RIGHT CHOICES PRODUCE DOGS ADAPTED, WILLING AND ABLE TO LIVE AND WORK WITH US, WHATEVER AND WHEREVER THE CHALLENGE.

[ WHISTLING ] [ SHEEP BLEATING ] BUT, AS THE VICTORIANS WERE TO DISCOVER 150 YEARS AGO, MAKING VERY DIFFERENT CHOICES WILL GET YOU VERY DIFFERENT, AND SOMETIMES PROBLEMATIC, RESULTS.

[ WHISTLE BLOWS ] THE INDUSTRIAL REVOLUTION IN THE 19th CENTURY WOULD CHANGE THE WORLD BEYOND RECOGNITION.

IN VICTORIAN ENGLAND, IT CREATED A HUGE UPSURGE IN THE URBAN MIDDLE CLASS -- A WHOLE NEW GROUP OF PEOPLE WITH MONEY AND TIME ON THEIR HANDS.

AND BECAUSE OF THEM, THE ARRIVAL OF THIS TINY CHINESE DOG IN QUEEN VICTORIA'S LONDON COURT IN 1860 WAS TO HAVE FAR-REACHING CONSEQUENCES.

[ BELL RINGS ] THE PEKINGESE WAS CREATED NOT BY THE HARSHNESS OF AN ENVIRONMENT, BUT BY THE POWER OF RELIGIOUS BELIEF.

ALSO KNOWN AS THE "LION DOG," THE PEKINGESE IS FIRST RECORDED TO HAVE BEEN KEPT IN CHINA AT THE TIME OF THE ZHOU DYNASTY 2,000 YEARS AGO.

CHINA HAD RECENTLY BECOME A BUDDHIST COUNTRY.

BUT THIS CONVERSION FACED A SIGNIFICANT STUMBLING BLOCK.

THE LION, WHICH BUDDHA HAD TAMED, CREATING A FAITHFUL SERVANT AND POWERFUL PROTECTOR, DIDN'T EXIST IN CHINA.

FACED WITH THE NEED FOR SUCH A POWERFUL RELIGIOUS SYMBOL, BUDDHIST MONKS TURNED TO DOGS FOR THE ANSWER AND CHOSE THE PUPPIES MOST LIKELY TO HELP.

Man: IF YOU LOOK IN ANY LITTER OF DOGS, THERE WILL BE A VARIATION IN SIZE OF PUPPIES.

AND IF YOU WANT TO DOWNSIZE, IF YOU SIMPLY BRED FROM THE SMALLER MEMBERS OF THE LITTER TO OTHER SMALL MEMBERS AND KEEP DOING THAT, A SELECTION THAT YOU SELECT TO BREED FROM ONLY SMALL DOGS, THEN YOU WILL DOWNSIZE IN TERMS OF THE SIZE OF THE BREED.

Abraham: THE PEKINGESE WAS MOLDED INTO EXISTENCE BY BREEDING FROM THE SMALLEST, HAIRIEST DOGS THE MONKS COULD FIND, TO PRODUCE A MINIATURE LION.

THEY WERE SO SUCCESSFUL THAT THE DOGS BECAME SACRED SYMBOLS, OWNED EXCLUSIVELY BY THE IMPERIAL FAMILY.

REMOVING THEM FROM THE PALACE PRECINCT WAS A CRIME PUNISHABLE BY DEATH.

THE PEKINGESE IS ONE OF THE EARLIEST BREEDS WITH A WRITTEN STANDARD SETTING OUT EXACTLY WHAT THE ANIMAL SHOULD OR SHOULD NOT LOOK LIKE.

THIS TEXT, WRITTEN BY THE EMPRESS DOWAGER TSU H'SI AND DISCOVERED IN THE MID-1800s, WOULD HAVE INFLUENCED WHICH PUPPIES WERE CHOSEN FOR BREEDING AND WHICH MAY HAVE BEEN DISCARDED.

As Empress Dowager: LET THE LION DOG BE SMALL.

LET ITS FACE BE BLACK.

LET ITS FOREHEAD BE STRAIGHT AND LOW.

LET ITS EARS BE SET LIKE THE SAILS OF A WAR JUNK.

LET ITS EYES BE LARGE AND LUMINOUS.

LET ITS NOSE BE LIKE THAT OF THE MONKEY GOD OF THE HINDUS.

LET ITS FORELEGS BE BENT, SO THAT IT SHALL NOT DESIRE TO WANDER FAR OR LEAVE THE IMPERIAL PRESENCE.

Abraham: THE EMPRESS DOWAGER'S INSTRUCTIONS WERE DISCOVERED UNDER DRAMATIC CIRCUMSTANCES.

IN 1860, THE SUMMER PALACE IN BEIJING WAS STORMED BY ENGLISH TROOPS, HERALDING THE END OF THE MIGHTY CHINESE EMPIRE.

THE IMPERIAL DOGS, CAREFULLY BRED AND NURTURED FOR MANY CENTURIES, WERE SLAUGHTERED TO PREVENT THEM FROM FALLING INTO FOREIGN HANDS.

BUT FIVE OF THE ANIMALS SURVIVED, UNNOTICED IN THE CHAOS.

THESE DOGS WERE BROUGHT TO ENGLAND, AND THE SMALLEST ONE WAS PRESENTED TO QUEEN VICTORIA.

ITS TINY LEGS AND FLATTENED SNOUT CAUSED A HUGE STIR AND BECAME A FAST FAVORITE IN HIGH SOCIETY.

OWNING A LAP DOG WAS THE ULTIMATE STATUS SYMBOL.

AND FOR THE NEWLY MONEYED MIDDLE CLASSES WITH TIME ON THEIR HANDS, IT WAS JUST THE INSPIRATION THEY'D BEEN LOOKING FOR.

BREEDING DOGS AND KEEPING THEM AS PETS, OR THE DOG FANCY, AS IT WAS KNOWN, QUICKLY BECAME THE HOBBY OF CHOICE -- AN AFFORDABLE OPPORTUNITY FOR THE MIDDLE CLASSES TO PRODUCE THEIR OWN VERSIONS OF THE ELITE'S ESSENTIAL CANINE ACCESSORY.

Woman: ONCE PEOPLE HAD THE LEISURE TIME TO START PLAYING AROUND WITH THE DIFFERENT SIZE AND FORMS OF DOGS, YOU CAN START SELECTING THE SMALLEST ANIMAL FROM A LITTER AND MATING THEM TOGETHER.

AND ALSO ANIMALS THAT WOULD BE SLIGHTLY UNUSUAL, THAT WOULD BE, ACTUALLY HAVE SOME OF THESE GENETIC MUTATIONS, THINGS LIKE LONG HAIR RATHER THAN SHORT HAIR OR DWARFED LEGS.

AND BECAUSE PEOPLE REALLY ARE CURIOUS, I THINK, ABOUT SOME OF THESE KINDS OF DIFFERENCES, IF YOU'VE GOT THE TIME AND ENERGY AND RESOURCES TO PLAY AROUND WITH THAT, I THINK IT'S PART OF OUR HUMAN NATURE TO JUST SEE WHAT WE CAN DO WITH THEM.

Abraham: THE VICTORIAN PASSION FOR BREEDING TINY DOGS ALSO APPEALED TO ANOTHER SIDE OF HUMAN NATURE.

A Y DOG HAS A PUPPY-LIKE APPEARANCE.

THE BIG EYES AND TINY NOSE REMIND US OF OUR OWN OFFSPRING, AND WE ARE PSYCHOLOGICALLY PROGRAMMED TO RESPOND AND WANT TO CARE FOR AND NURTURE THE DOG IN THE SAME WAY WE WOULD RESPOND TO A BABY.

SO IT'S NOT SURPRISING THAT A TINY DOG FROM CHINA WOULD HAVE SUCH AN EFFECT ON THE VICTORIAN DOG BREEDERS -- AN EFFECT THAT WAS TO HAVE FAR-REACHING CONSEQUENCES.

Man: THE DEVELOPMENT OF THIS DOG-BREEDING HOBBY DOES MARK A TOTALLY NEW CHANGE, A NEW TREND, IN OUR RELATIONSHIP WITH THE DOMESTIC DOG.

ALL OF A SUDDEN, THE EMPHASIS SHIFTED FROM THE KIND OF JOB THE DOG COULD PERFORM TO BASICALLY WHAT IT LOOKED LIKE.

AND THIS IS AN ENTIRELY NEW WAY, REALLY, FOR HUMANS TO LOOK AT DOGS AS OBJECTS OF AESTHETIC APPRECIATION.

Abraham: IN 1873, THE KENNEL CLUB WAS FORMED IN LONDON, THE FIRST OF ITS KIND IN THE WORLD.

AS THE HEADQUARTERS OF THE DOG FANCY, IT KEPT TRACK OF THE MULTITUDE OF NEW TYPES BY SETTING INDIVIDUAL STANDARDS FOR EVERY BREED.

[ DOG BARKS ] IT WAS ALSO THE DRIVING FORCE BEHIND DOG SHOWS -- AN OPPORTUNITY FOR THE PROUD DOG BREEDER TO PARADE HIS LATEST CREATION.

THE DOG SHOW -- WHERE THE WINNER WAS THE CLOSEST MATCH TO THE KENNEL CLUB BREED STANDARD -- BECAME A FIXTURE OF THE SOCIAL CALENDAR.

[ DOG YIPS ] THIS NEW PASSION LED TO A PROFUSION OF NEW BREEDS.

UP UNTIL THE INDUSTRIAL REVOLUTION, DOGS HAD BEEN LOOSELY CATEGORIZED INTO 40 WORKING TYPES.

AND FROM THIS MIXED BATCH, THE VICTORIANS CREATED A PHENOMENAL ARRAY OF SHAPES AND SIZES, WHICH GAVE US THE 400 INTERNATIONALLY RECOGNIZED BREEDS WE KNOW TODAY.

Man on speaker: THE MINIATURE PINCER.

Abraham: THE MODERN DOG IS QUITE SIMPLY THE MOST VARIED MAMMAL IN THE WORLD.

NO OTHER HAS EVEN A QUARTER OF THE RANGE OF THE INDIVIDUAL CHARACTERISTICS FOUND IN DOGS.

Man: AND NOW, WE HAVE HERE THE CHINESE CRESTED.

[ APPLAUSE ] THE INCREDIBLE VARIETY WE CAN SEE IN DOMESTIC DOGS IS EVEN MORE ASTOUNDING WHEN YOU CONSIDER THEIR GENETIC HISTORY.

ALL DOGS -- WHATEVER THEIR SHAPE AND SIZE -- ARE DIRECT DESCENDANTS OF THE WOLF.

[ HOWLING ] Man: IF YOU TRY TO IMAGINE GOING FROM SOMETHING LIKE A WILD WOLF, YOU KNOW, THOSE GREAT BIG YELLOW EYES LOOKING OUT AT YOU OUT OF THE FOREST, AND TRANSFORMING THAT ANIMAL INTO A PEKINGESE.

FROM A GENETIC POINT OF VIEW, YOU'VE GOT TO UNDERSTAND -- WHAT A REVELATION, THAT YOU COULD ACTUALLY DO SUCH A THING.

Abraham: THE CONVENTIONAL DARWINIAN UNDERSTANDING OF EVOLUTION AS A SLOW AND GRADUAL PROCESS JUST CANNOT EXPLAIN HOW THE GENES OF A WOLF CAN GENERATE THIS HUGE VARIATION IN JUST 15,000 YEARS.

SO HOW DID IT HAPPEN?

Crockford: OKAY, PUPPY.

ZOOLOGIST SUSAN CROCKFORD BELIEVES THAT SOMETHING MUST BE CONTROLLING THE GENES AND THEIR EXPRESSION.

SHE IS STUDYING ONE OF THE HORMONES THAT DETERMINE THE DOG'S GROWTH.

Crockford: THESE PUPPIES AROUND ME ARE GREAT DANES, AND, AMAZINGLY, THEY ARE EXACTLY THE SAME AGE AS THIS LITTLE CHIHUAHUA HERE.

EACH OF THESE DIFFERENT BREEDS IS GROWING AT QUITE A DIFFERENT RATE.

THE GREAT DANE PUPPIES ARE ON A REALLY, REALLY RAPID GROWTH TRAIN, TO ALLOW THEM TO BE ONE OF THE TALLEST OF THE DOG BREEDS THAT WE HAVE TODAY.

Abraham: ACCORDING TO CROCKFORD, THE WAY A DOG GROWS DEPENDS ON HOW MUCH THYROXIN IS AVAILABLE AT CRITICAL TIMES.

IN THE WOMB, THE PUPPY RECEIVES PULSES OF BREED-SPECIFIC AMOUNTS OF THYROXIN FROM THE MOTHER, VIA THE PLACENTA.

AFTER IT'S BORN, THE PATTERN IS SET.

THE PUPPY'S OWN THYROID GLAND TAKES OVER PRODUCTION AND RELEASES THYROXIN UNTIL THE DOG'S ADULT SIZE IS FIXED.

THIS CAN HAPPEN AT VERY DIFFERENT TIMES IN DIFFERENT DOGS.

Crockford: NOW WE'VE GOT THESE TWO BREEDS AS TWO-YEAR-OLDS.

THE CHIHUAHUA IS FULLY GROWN AT THIS POINT.

HE'S SEXUALLY MATURE, HE'S PUT ON WEIGHT, HE'S GOT THE FULL COORDINATION OF A TRUE ADULT.

THIS BIG BOY STILL HAS A WAYS TO GO.

HIS BONES MIGHT BE ALMOST FINISHED GROWING, BUT HE'S GOT SOME WEIGHT TO PUT ON STILL, SOME COORDINATION TO DEVELOP, AND THAT'S GOING TO TAKE A FEW MORE MONTHS.

Abraham: FULLY GROWN, THE GREAT DANE CAN WEIGH 170 POUNDS AND THE CHIHUAHUA AS LITTLE AS TWO -- AN EXTREME EXAMPLE OF HOW DIFFERENT GROWTH PATTERNS CAN PRODUCE SUCH DIFFERENT BREEDS.

Crockford: EACH BREED OF DOG ACTUALLY HAS A BREED-SPECIFIC GROWTH RATE.

SO IF THYROXIN RHYTHMS ARE ACTUALLY WHAT IS CONTROLLING THAT GROWTH RATE, WE CAN THEN PROPOSE THAT THYROXIN RHYTHMS MUST BE DIFFERENT FOR EACH OF THE DIFFERENT KINDS OF BREEDS.

Abraham: SUSAN'S THEORY IS PROVOCATIVE, BUT IT COULD BE AN EXPLANATION FOR HOW THE DOG HAS TRANSFORMED INTO OVER 400 DIFFERENT BREEDS IN THE BLINK OF AN EVOLUTIONARY EYE.

AND OF ALL THE BREEDS IN THE WORLD, THE BULLDOG IS PERHAPS THE MOST OUTSTANDING EXAMPLE OF JUST HOW FLEXIBLE THE DOG'S FORM IS.

Woman: IZZY!

IZZ!

IZZY-LOU, COME ON.

Abraham: DEBBIE CHARWIN, A BULLDOG BREEDER FOR OVER 10 YEARS AND A SHOW JUDGE, HAS A PROFESSIONAL APPRECIATION OF THE BREED'S SPECIAL FEATURES.

Charwin: THEIR NOSE SHOULD BE SET BACK FROM THE FACE, GOING INTO A FURROW, WHICH IS THIS BIT, OVER A BROAD HEAD, FLATTISH SKULL, AND THESE LOVELY ROSE EARS.

THEY SHOULDN'T BE PRICKED UP OR ANYTHING, THAT IS INCORRECT.

THIS IS WHAT THEY CALL AN UPSWEEP, UPSWEEP JAW WHICH COMES DOWN AND GOES ROUND.

SHE'S GOT A NICE WIDTH OF CANINE, AND THAT'S WHAT THEY CALL UNDERSHOT.

THE TOP LOT SIT RIGHT BACK.

THEY CAN BE LIKE A PICKET FENCE RATHER THAN IN A STRAIGHT LINE, AS LONG AS THEY ARE THERE.

NOT MUCH ATTENTION IS PAID TO THAT, REALLY.

THAT'S ALLOWED.

AS YOU CAN SEE, SHE HAS GOT A VERY POWERFUL NECK, INTO THESE VERY, WHAT THEY CALL TACKED-ON SHOULDERS.

IF YOU LOOK AT THE WHOLE DOG WHEN THEY ARE SET UP, THEY LOOK LIKE THEIR SHOULDERS HAVE BEEN PUT ON AS AN AFTERTHOUGHT.

AND THAT IS UNIQUE TO THIS BREED.

YOU SHOULD BE ABLE TO CHOP THE HEAD OFF -- SOUNDS AWFUL, AND STICK IT BETWEEN THEIR LEGS, AND IT SHOULD FIT NICE AND SQUARE.

IT MEANS THE DOG IS WELL PROPORTIONED.

Abraham: FOR DEBBIE, IT'S NOT JUST JUST THE BULLDOG'S PHYSICAL ATTRIBUTES THAT MAKE IT SO ATTRACTIVE.

Charwin: THEY'RE A VERY BIG DOG IN A SMALL BODY.

THEY ARE A TRUE CHARACTER.

I THINK SHE'S JUST PERFECT.

TO ME.

Abraham: HISTORIAN DAVID HANCOCK IS ALSO A BIG BULLDOG FAN, BUT HE PREFERS A MUCH OLDER VERSION.

Man: IF YOU LOOK AT THE BULLDOG OF 1870 AND THE BULLDOG OF THE TURN OF THE CENTURY, TO MY MIND THERE IS NO COMPARISON.

THE 1870 DOG IS AN ATHLETIC DOG, IT'S A HANDSOME DOG, AND IT'S A HEALTHY DOG.

THIS ONE, THAT HAS DEVELOPED SINCE, IT'S NOT WELL BUILT AT ALL.

ITS JAW IS TOO SHORT, ITS BUILD IS TOO SQUAT, THERE IS NO CANINE ATHLETICISM THERE AT ALL.

IT IS PURELY BREEDER WHIM.

Abraham: ORIGINALLY, THE BULLDOG WAS NOT A BREED, AS WE KNOW IT TODAY.

IT WAS SIMPLY A GENERAL TERM FOR A DOG THAT HAD A CERTAIN SET OF TALENTS.

BULLDOGS WERE USED BY BUTCHERS TO CONTROL LIVESTOCK IN THE SLAUGHTERHOUSE YARD.

THEIR SPECIALIST SKILL WAS TO PIN DOWN WAYWARD CATTLE.

BULLDOG OWNERS WOULD SHOW THIS OFF AT BULL-BAITING EVENTS FOR THE PUBLIC TO WATCH.

Hancock: THESE ARE THE BULLDOGS AT THE BAITING RING, TAKEN ABOUT 1830.

YOU NOTICE THAT THE BULLDOGS HAD GOOD, LONG MUZZLES.

THEY DO NOT HAVE SHORT, SQUASHED FACES.

THEY ARE AGILE, ATHLETIC, CAPABLE OF LIGHTNING MOVEMENT.

IF THEY DIDN'T, IF THEY COULDN'T, THE BULL WOULD HAVE VERY QUICKLY ENDED THEIR LIVES.

Abraham: BY THE END OF THE CENTURY, BULL-BAITING HAD BEEN BANNED, THE FIGHTING ARENAS CLOSED, AND THE BULLDOG ENTERED THE VICTORIAN SHOW RING, INSTEAD.

Hancock: THIS IS A DEPICTION OF THE TREMENDOUS CHANGE THAT TOOK PLACE IN BULLDOG BREEDING AND FANCYING.

THIS BECAME THE BULLDOG THAT SURVIVED.

THE OLD TYPE WAS NO LONGER FAVORED.

THE GREAT SADNESS OF THE PICTURE IS THAT THE FAR HEALTHIER BULLDOG IS DEPARTING THE SCENE, AND A LESS HEALTHY DOG, MORE EXAGGERATED DOG, IS TAKING CENTER STAGE.

Abraham: THE STANDARD THAT WAS DRAWN UP FOR THE BULLDOG JUST OVER 100 YEARS AGO IS WHAT CREATED THE BREED AS WE KNOW IT TODAY.

THE SNOUT HAS SHORTENED DRAMATICALLY, BY OVER THREE INCHES.

SO ITS TEETH ARE OFTEN OVERCROWDED AND PROTRUDE OUTSIDE THE MOUTH.

BULLDOGS ARE BRED TO HAVE BROAD BREAST BONES AT THE FRONT AND NARROWER HIPS AT THE BACK.

THE PROCESS HAS BEEN SO EFFECTIVE THAT MANY PUPPIES ARE NOW TOO WIDE TO PASS THROUGH THE BIRTH CANAL, AND ARE DELIVERED BY CAESAREAN SECTION INSTEAD.

ITS IMPRESSIVE WIDE SHOULDERS MAKE IT LOOK POWERFUL, BUT THE BULLDOG'S STRENGTH IS ONLY SKIN DEEP.

LIKE IT OR LOATHE IT, THE PHYSICAL CHANGES THAT TRANSFORMED THE BULLDOG ARE VISUALLY STRIKING.

AND ALL PEDIGREE DOGS HAVE GONE THROUGH A SIMILAR PROCESS OF SELECTIVE BREEDING.

SOME EXPERTS THINK IT'S TIME WE STOPPED TO CONSIDER THE CONSEQUENCES FOR THE DOG.

Man: THE SHAR-PEI IS A LOVELY DOG, LOVELY TEMPERAMENT.

BUT PHYSICALLY THEY ARE JUST A DISASTER.

THEY HAVE VERY COMMON EYE PROBLEMS WHERE THEY HAVE TO HAVE LAYERS OF SKIN REMOVED FROM THEIR EYELIDS BECAUSE IT'S SO HEAVY, IT ACTUALLY STARTS TO AFFECT THEIR EYES, AND THEY CAN END UP NOT BEING ABLE TO SEE.

THEIR SKIN IS NOW SO LOOSE THAT APPARENTLY THE SAYING IS, A SHAR-PEI COULD TURN AROUND IN ITS OWN SKIN, IT HAS SO MUCH LOOSE SKIN.

THE RESULT OF THAT IS, IT FORMS THESE HEAVY, THICK LAYERS OF SKIN.

AN EXCESS OF BODY HEAT BUILD UP WITHIN THOSE THAT CAN START TO CAUSE SORES AND IRRITATIONS UNDER THE SKIN.

AND PEOPLE DON'T WANT THEM UNLESS THEY ARE REALLY WRINKLY, YOU KNOW, WHEN IN FACT THEY NEED TO BE MUCH LESS WRINKLY.

Abraham: PRODUCING SUCH UNUSUAL FEATURES AS WRINKLY SKIN CAN REQUIRE THE MATING OF VERY CLOSELY RELATED INDIVIDUALS.

AND IT'S THIS INBREEDING THAT HAS CAUSED SOME OF THE CLINICAL PROBLEMS THAT CAN OCCUR IN PEDIGREE DOGS.

Sampson: WHAT WE'VE DONE IN THE LAST COUPLE OF HUNDRED YEARS IS TO ESSENTIALLY NARROW DOWN THESE GENE POOLS.

ONE OF THE CONSEQUENCES IS THAT IT CAN BRING TOGETHER UNWANTED MUTATIONS THAT CAN CAUSE CLINICAL PROBLEMS.

AND BECAUSE OF THE NARROWNESS IN OUR MATING PROGRAMS -- DOG BREEDERS CALL IT LINE BREEDING, IN HUMANS, WE CALL IT INBREEDING -- BECAUSE OF THOSE, THOSE VERY FEATURES OF THE WAY DOGS HAVE BEEN BRED, THE CHANCES OF THESE RECESSIVE MUTATIONS BEING BROUGHT TOGETHER ARE FAR HIGHER.

AND THEREFORE, THERE ARE FAR MORE INHERITED DISEASES AS A CONSEQUENCE.

Abraham: BUT THE CHOICES WE MAKE ABOUT WHICH DOGS TO BREED CAN HAVE POSITIVE OUTCOMES.

WE CAN USE EXACTLY THE SAME PRACTICES TO REVERSE AND REPAIR EARLIER MISTAKES.

Sampson: THE WAY THAT DOGS LOOK TODAY IS CERTAINLY NOT STUCK WHERE IT IS.

IT CAN BE AN ONGOING PROCESS.

IT'S A VERY PLASTIC SITUATION.

IT'S JUST A QUESTION OF GETTING THE BREEDERS TO CHANGE THEY WAY THEY SELECT PARENTS TO BREED FROM.

THAT TIME FRAME CAN BE RELATIVELY SHORT, AS FEW AS THREE OR FOUR GENERATIONS.

THE SAME GENETIC PRACTICES THAT HAVE BEEN USED OVER THE YEARS TO PRODUCE WHAT WE HAVE TODAY, THEY CAN BE USED AS EFFECTIVELY TO REVERSE SOME OF THESE EXAGGERATED FEATURES THAT WE SEE.

Abraham: JUST AS IT'S BEEN FROM THE BEGINNING, THE CHOICES WE MAKE WILL CONTINUE TO SHAPE AND CHANGE THE DOGS WITH WHICH WE NOW SHARE OUR LIVES.

Crockford: I SEE IT AS ACTUALLY MOVING TOWARDS JUST MODIFYING THOSE KINDS OF SELECTION PROCEDURES SO THAT WE END UP WITH DOGS OF DIFFERENT TYPES -- PERHAPS NOT NEARLY SO MANY, PERHAPS NOT NEARLY SO EXTREME -- BUT THAT THERE WILL ALWAYS BE DIFFERENCES IN SIZE, SHAPE AVAILABLE TO US TO CHOOSE FROM.

Abraham: THE VICTORIAN PASSION FOR BREEDING DIDN'T JUST RESULT IN DRAMATIC PHYSICAL CHANGES IN DOGS.

IT FUNDAMENTALLY ALTERED OUR RELATIONSHIP WITH THEM.

Serpell: I THINK ONE OF THE BYPRODUCTS OF THIS RECENT EVOLUTION OF OUR RELATIONSHIP WITH DOGS IS THAT WE KIND OF SEEM TO HAVE LOST TOUCH WITH WHAT DOGS ARE.

THEY'RE STILL DOGS, AND THEY STILL HAVE THEIR OWN NEEDS.

PEOPLE NEED TO REALLY GET BACK IN TOUCH WITH THE REAL DOG, BEHIND THAT KIND OF, THESE SUPERFICIALITIES OF APPEARANCE, AND START THINKING SERIOUSLY ABOUT WHETHER THEY SHOULD REALLY KEEP A DOG IF THEY AREN'T GOING TO MAKE FOR THAT ANIMAL AN ENVIRONMENT THAT WILL SATISFY ITS NEEDS.

Abraham: THE RECENT PHYSICAL CHANGES WE'VE MADE TO THE DOG CAN BE REVERSED, BUT ITS BEHAVIOR AND INSTINCTS ARE NOT SO EASILY CHANGED.

IF WE FORGET THIS, THE RESULTS CAN BE DEVASTATING.

[ DOGS BARKING ] STOP IT!

[ BARKING ] Abraham: 4.7 MILLION PEOPLE ARE BITTEN BY DOGS EVERY YEAR IN THE U.S., AND MOST OF THEM ARE CHILDREN.

OUT OF THE 65 MILLION DOGS THAT AMERICANS OWN, AS MANY AS ONE IN FIVE WILL BE PUT TO SLEEP BECAUSE ITS OWNER IS UNABLE TO MANAGE ITS BEHAVIOR.

[ SNARLING ] [ DOGS BARKING ] [ BARKS ] FIVE MILLION DOGS END UP IN SHELTERS EVERY YEAR.

[ BARKS ] [ BARKING ] FOR ROBERT ALLEYNE, THE PROBLEM LIES IN POOR SOCIALIZATION AND IN A DOG'S INTRINSIC BEHAVIOR.

KEEPING DOGS PURELY AS DOMESTIC PETS IS A MODERN PHENOMENON.

BEFORE THE VICTORIANS INVITED THEM INTO OUR HOMES, WORKING DOGS WERE BRED OVER THOUSANDS OF YEARS TO DO A VERY SPECIFIC JOB.

THAT BEHAVIOR HAS NOW BECOME PART OF THE DOG'S GENES.

IT'S WHAT BIOLOGISTS CALL HARD-WIRED.

Man: DIFFERENT TYPES OF DOGS WILL EXHIBIT DIFFERENT TYPES OF HARD-WIRED BEHAVIOR.

SO WITH THE GERMAN SHEPHERD, FOR EXAMPLE, WE SEE GUARDING BEHAVIORS.

WITH COLLIE TYPES, WE'LL FIND HERDING BEHAVIORS, SO THE OWNER WILL SAY THAT THE DOG HERDS ALL THE CHILDREN INTO A CORNER OF THE ROOM AND WON'T LET THEM MOVE.

IF YOU PICK UP A BALL AND GO TO THROW IT, THE DOG RUNS IN CIRCLES AROUND YOU.

Abraham: AND ONE OF THE MOST POPULAR PETS OF ALL IS, IN FACT, A NATURAL-BORN KILLER.

Alleyne: WITH TERRIERS, YOU'LL SEE A DIFFERENT TYPE OF HARD-WIRED BEHAVIOR.

TERRIERS WERE BRED TO KILL OTHER ANIMALS, WITHOUT EXCEPTION.

ALL OF THE TERRIERS WERE BRED FOR THAT.

SO YOU'LL SEE OFTEN VERY, VERY AGGRESSIVE BEHAVIOR IN TERRIERS.

THEY WANT TO GET HOLD OF THINGS AND KILL THEM.

SO I'LL GET OWNERS SAYING, "I DON'T UNDERSTAND WHY MY JACK RUSSELL WANTS TO KILL TIMMY'S RABBIT," YOU KNOW.

[ BARKING ] Abraham: A TERRIER DOESN'T THINK IT'S BEHAVING BADLY.

IT'S JUST DOING WHAT ITS INSTINCTS TELL IT TO DO -- INSTINCTS THAT WE NURTURED AND VALUED IN VERY DIFFERENT TIMES.

THIS PINT-SIZED KILLER EMERGED IN 17th-CENTURY ENGLAND AS A WORKING-CLASS DOG PROTECTING FARMERS FROM A PEST THAT THREATENED TO DESTROY THEIR LIVELIHOODS.

AN INFESTATION OF RATS IN YOUR GRAIN STORE COULD SPOIL AN ENTIRE CROP, AND THE TERRIER WAS HIGHLY EFFECTIVE AT PEST CONTROL.

YAH, YAH!

YAH, YAH, YAH, YAH!

Abraham: EVERYTHING ABOUT THE TERRIER IS DESIGNED TO KILL RATS...

IN HIGH NUMBERS, AT HIGH SPEED.

THE TERRIER WAS BRED TO HAVE A STURDY NECK FOR ITS TINY SIZE AND TO KILL ITS PREY WITH A SINGLE POWERFUL SHAKE.

Hancock: IF YOU HAD A COTTAGE AND NOT MUCH MONEY, BUT YOU NEEDED YOUR GRAIN STORE TO BE PROTECTED, YOUR LARDER TO BE PROTECTED, YOUR TERRIER DID THAT FOR YOU AND WASN'T A BIG DOG, DIDN'T EAT A LOT, MADE FEW DEMANDS ON YOU AND SO WAS A VERY VALUABLE MEMBER OF YOUR HOUSEHOLD.

Abraham: THE TERRIER'S SMALL AND APPEALING FEATURES CONCEAL A MUCH LARGER DOG'S PERSONALITY.

CAREFUL BREEDING AND SELECTION CREATED A TINY DOG THAT IS FEARLESS, WILLING TO TAKE ON ANYTHING.

[ SNARLING ] ITS FEISTY TEMPERAMENT AND DESIRE TO KILL SMALL RODENTS CAN BE DISASTROUS, ESPECIALLY IF IT'S FEELING THREATENED IN THE CONFINES OF THE MODERN HOME.

[ BARKING ] [ SNARLING ] NOW, NOW, CALM.

[ SNARLING ] Abraham: WHEN A WORKING DOG IS NOT WELL MANAGED AS A PET AND POORLY SOCIALIZED, ITS INSTINCTIVE BEHAVIOR CAN BECOME UNCONTROLLABLE.

THIS IS ONE OF THE REASONS WHY UP TO FIVE MILLION DOGS ARE GIVEN UP BY THEIR OWNERS EACH YEAR.

Alleyne: FOR THOUSANDS AND THOUSANDS OF YEARS, MAN AND DOG HAVE HAD A VERY STRONG, EFFICIENT WORKING SYMBIOTIC RELATIONSHIP, AND THAT RELATIONSHIP NOW IS IN CRISIS.

I THINK THE KEY REASONS FOR THIS CRISIS ARE ALMOST TOTAL BREAKDOWN IN COMMUNICATION, A LACK OF UNDERSTANDING OF WHAT OUR DOG IS TODAY AND HOW WE CAN ENSURE THAT WE MAINTAIN THE DOG OF TOMORROW.

WE HAVE COMPLETELY FORGOTTEN THE NATURE OF THIS ANIMAL AND WHAT IT WAS DESIGNED FOR.

Abraham: ROBERT, LIKE MOST PEOPLE TODAY, DOESN'T RELY ON A DOG THAT WORKS FOR A LIVING BY HUNTING, HAULING, OR HERDING.

BUT IN THE MODERN WORLD, DOGS STILL HAVE HUGE POTENTIAL TO HELP US SURVIVE.

[ THUNDER ] FOR THOUSANDS OF YEARS, MAN HAS TAKEN ADVANTAGE OF THE DOG'S ABILITY TO TRACK A SCENT.

[ BARKING ] TODAY THESE BLOODHOUNDS ARE FOLLOWING A MAN'S SCENT TRAIL FOR FUN, BUT THEY WERE ONCE USED TO HUNT DOWN CRIMINALS AND GANGSTERS.

THEIR SENSE OF SMELL IS SO ACUTE, THEY CAN FIND A SCENT TRAIL UP TO TWO WEEKS OLD.

[ BARKING ] TO UNDERSTAND HOW THE DOG'S SENSE OF SMELL CAN BE A THOUSAND TIMES BETTER THAN HUMANS', WE HAVE TO TAKE A CLOSE-UP LOOK AT HOW THE DOG'S NOSE WORKS.

LONG, PENDULOUS EARS AND A WRINKLY FACE WAFT SCENT PARTICLES UP FROM THE GROUND.

HIDDEN INSIDE THE NOSTRILS IS AN INCREDIBLE STRUCTURE -- THE SECRET OF THE DOG'S POWERS.

A MAZE OF BONY PASSAGES, LINED WITH OVER 200 MILLION NASAL RECEPTOR CELLS, TRAP THE INCOMING SCENT PARTICLES.

THERE'S A FURTHER UNIQUE ADAPTATION THAT PREVENTS AN OUTWARD BREATH FROM BLOWING AWAY ANY SCENT PARTICLES DIRECTLY IN FRONT OF THEM.

A FLAP OF SKIN MOVES IN AND SEALS THE FRONT OF THE NOSTRILS, FORCING THE AIR OUT SIDEWAYS AND BACKWARDS -- LEAVING PARTICLES ON THE GROUND IN FRONT UNDISTURBED, READY FOR THE DOG'S NEXT SNIFF.

[ BARKING ] TODAY BLOODHOUNDS AND MANY OTHER BREEDS ARE ALREADY DOING VERY MODERN JOBS -- DETECTING BOMBS, COUNTERFEIT MONEY, AND DRUGS.

[ BARKING ] Man: GOOD GIRLS AND BOYS!

Abraham: IF WE CAN PROPERLY UNDERSTAND THEIR INCREDIBLE ABILITY TO DETECT EVEN THE TINIEST TRACES OF A SCENT, THEY COULD HELP US CATCH ONE OF TODAY'S BIGGEST KILLERS.

[ BARKING ] AT AMERSHAM HOSPITAL IN ENGLAND, CAROLYN WILLIS AND CLAIRE GUEST ARE PART OF A GROUNDBREAKING MEDICAL RESEARCH UNIT.

HELLO, POPPETS, HELLO!

Abraham: DAISY AND TANGLE ARE KEY MEMBERS OF THEIR TEAM.

THEY ARE LEARNING HOW TO SMELL CANCER.

Woman: DISEASES ALWAYS GIVE RISE TO ABNORMAL EVENTS WITHIN CELLS.

AND SOME OF THAT IS THE PRODUCTION OF DIFFERENT TYPES OF STRESS-RELATED MOLECULES.

AND SOME OF THESE WILL THEN GIVE RISE TO VOLATILE CHEMICALS, WHICH WILL SMELL.

THERE WILL BE VERY LIGHT MOLECULES, COME UP INTO THE ATMOSPHERE, INTO THE AIR.

AND, SAY, DOGS THAT ARE PARTICULARLY SENSITIVE CAN PICK THEM UP MORE EASILY.

NOW, THESE ARE CONTROLLED SAMPLES GOING DOWN HERE NOW, AND THEY ARE A MIXTURE OF SAMPLES FROM NORMAL, HEALTHY PEOPLE, BUT ALSO SAMPLES FROM PEOPLE WHO ARE OLDER AND WHO HAVE UROLOGICAL DISEASE, SO THEY ARE A MIXTURE OF CONTROLS.

Abraham: SOMEWHERE IN THE COMPLEX COCKTAIL OF ODORS FROM THESE URINE SAMPLES IS THE SIGNATURE SMELL OF BLADDER CANCER.

FAR BEYOND THE POWERS OF THE HUMAN NOSE, THIS TELLTALE SCENT IS WHAT THE DOGS ARE BEING TRAINED TO DETECT.

Woman: THE THING THAT IMPRESSES ME PARTICULARLY ABOUT WORKING WITH DOGS IS THEIR FANTASTIC ABILITY TO CONCENTRATE ON THEIR JOB WHEN THEY WORK WITH YOU.

I CAN HONESTLY SAY THAT THE DAYS THAT I TRAIN WITH THESE DOGS, THAT THEY ALWAYS ARE WAGGING THEIR TAILS, "WHAT CAN WE DO?"

AND DESPERATELY TRYING TO GET IT RIGHT.

YOU NEVER FEEL THAT YOU ARE MAKING THEM DO IT OR FORCING THEM TO DO IT.

AND YOU ALWAYS FEEL THAT, WHEN THEY GET IT RIGHT, THEY GET THAT SENSE OF, "YES, DONE IT!"

AND THAT JUST MAKES THEM FANTASTIC CREATURES TO WORK WITH.

Willis: SO THIS ONE IS THE URINE SAMPLE FROM A CANCER PATIENT, AND IT'S GOING INTO "C." TANGLE, TANGLE.

GOOD BOY.

GOOD BOY.

SICK SEEK, SICK SEEK.

Abraham: TANGLE IS A WELL-SOCIALIZED COCKER SPANIEL, AND CLAIRE AND CAROLYN ARE HONING HIS SKILLS BY GIVING HIM THE MOST DIFFICULT SAMPLES THEY HAVE.

IS IT "C"?

GOOD BOY, GOOD BOY!

Abraham: CAROLYN IS CONFIDENT THAT THE DOG'S ABILITY TO GIVE US AN EARLY WARNING OF CANCER WILL HELP US TO CREATE NEW, MUCH MORE EFFECTIVE WAYS TO DIAGNOSE DISEASE.

Willis: I THINK DOGS HAVE THE MOST ENORMOUS POTENTIAL TO HELP US IN THE MEDICAL ARENA.

THEY HAVE HELPED US FOR CENTURIES IN TERMS OF HERDING AND TRACKING, BUT NOW I THINK WE CAN EXPLOIT THEIR SENSE OF SMELL TO REALLY HELP US DIAGNOSE DISEASE AND TO HELP THE MANAGEMENT OF PATIENTS WHO ACTUALLY ARE SUFFERING WITH CERTAIN DISEASES.

I THINK THEY HAVE ENORMOUS POTENTIAL.

COME ON DAISY, DAISY.

GOOD GIRL.

DAISY, SICK SEEK.

SICK SEEK.

GOOD GIRL!

WHAT A CLEVER GIRL!

GOOD GIRL!

WHAT A CLEVER GIRL!

Abraham: 4,000 MILES AWAY, THE DISEASE-DETECTING TALENTS OF DOGS HAVE ALREADY CHANGED THIS FAMILY'S LIFE.

IF IT WASN'T FOR GERMAN SHEPHERD, DELTA, THIS BOY WOULDN'T BE ALIVE.

JOSEPH REINKEMEYER IS 13 YEARS OLD AND HAS CONGENITAL TYPE ONE DIABETES.

HIS BODY IS UNABLE TO PRODUCE INSULIN, THE HORMONE THAT CONTROLS THE BODY'S BLOOD SUGAR, AND THIS CAUSES SEIZURES.

HE WOULD BITE AT US, HE WOULD KICK, HE WOULD HIT.

HE WOULD JUST SCREAM IN TERROR.

HE WAS SEEING MONSTERS.

EVEN IF WE TRIED TO GET JUICE IN HIM OR SOMETHING LIKE THAT, HE WOULD FIGHT IT OFF, THINKING IT WAS A MONSTER COMING AFTER HIM.

Abraham: JOSEPH WAS FIRST DIAGNOSED AT THE AGE OF SEVEN, AND HIS REGULAR DIABETIC SEIZURES WOULD TERRIFY BOTH HIM AND HIS PARENTS.

Michele: IT WAS HALLUCINATIONS, BASICALLY, AND HE WOULD HAVE THOSE EVERY TIME.

WE USED TO SCREAM AT HIM BECAUSE HE COULDN'T HEAR WHAT WE WERE SAYING, BUT IF WE YELLED LOUD ENOUGH, HE COULD HEAR A NOISE, AND HE'D KNOW THAT THAT WAS US.

Abraham: ONCE A SEIZURE HAS STARTED, JOSEPH'S PARENTS HAVE ONLY 15 MINUTES TO GIVE HIM AN INJECTION TO BOOST HIS BLOOD SUGAR.

LONGER THAN THIS, AND THE CONSEQUENCES COULD BE FATAL.

Michele: MY HUSBAND WAS WORKING FULL TIME.

I HAD QUIT MY JOB.

AND WE WERE LITERALLY CHECKING HIM EVERY HOUR ON THE HOUR, AND STILL HAVING THE SEIZURES.

EVERY TIME HE WOULD HAVE A SEIZURE, I WOULDN'T SLEEP FOR NIGHTS, BECAUSE I WAS SCARED TO DEATH THAT HE WAS GOING TO HAVE ANOTHER ONE.

HE SLEPT IN THE BED WITH US.

HE QUIT GOING ANYWHERE.

HE WOULDN'T SPEND THE NIGHT WITH HIS BEST FRIEND.

HE WOULDN'T LET HIS FRIEND SPEND THE NIGHT WITH HIM, BECAUSE HE WAS AFRAID THAT HE'D SEE THAT.

Abraham: AFTER MONTHS OF KNIFE-EDGE WORRY, MICHELE MADE A LIFE-CHANGING DISCOVERY.

Michele: AFTER JOSEPH'S 11th SEIZURE, HE WAS REALLY SCARED OF GOING BACK TO SLEEP.

HE HAD ASKED ME TO STAY AWAKE SO THAT HE WOULD NOT HAVE ANOTHER SEIZURE.

SO I AGREED TO STAY UP, AND I WAS ON THE INTERNET.

YOU, AS A PARENT, AT FIRST, YOU ARE IN DENIAL.

YOU KNOW, "THIS CAN'T BE REAL.

THERE HAS TO BE A BETTER ANSWER."

AND I READ ABOUT A WOMAN WHOSE DOG HAD STARTED NATURALLY ALERTING TO THIS, AND ABOUT 50 PERCENT OF THE TIME HE WOULD LET HER KNOW WHEN HER BLOOD SUGARS WERE GOING LOW.

SO SHE TRAINED HIM TO GO TO THE FRIDGE AND GET HER A COKE WHEN SHE WAS GOING LOW.

Abraham: HAVING PREVIOUSLY TRAINED SEARCH AND RESCUE DOGS, MICHELE IMMEDIATELY WENT LOOKING FOR A PUPPY THAT WAS EAGER TO LEARN.

SHE FOUND AN EIGHT-WEEK-OLD GERMAN SHEPHERD -- DELTA.

AND ALTHOUGH THEY WERE WARNED THAT TRAINING A DOG TO ALERT FOR TYPE ONE DIABETES MIGHT BE VERY DIFFICULT, THEY PINNED ALL THEIR HOPES ON DELTA'S AMAZING SENSE OF SMELL.

Man: JOSEPH LOW?

YES, YES, GOOD GIRL.

LET'S GO GET HIM.

WHERE'S JOSEPH?

JOSEPH.

Abraham: THE RESULTS HAVE BEEN MUCH MORE THAN THEY COULD EVER HAVE HOPED FOR.

THEY TRAINED DELTA TO DETECT NOT ONLY WHEN JOSEPH IS ABOUT TO HAVE A SEIZURE.

SHE CAN ALSO SMELL THE SUBTLE BODY CHEMISTRY CHANGES THAT WARN HIS BLOOD SUGAR LEVELS ARE FALLING, WELL BEFORE THE SEIZURE HAPPENS.

Michele: NOW THAT DELTA'S ALERTING, IT'S NOT A BIG PANIC.

IT'S NOT...IT'S, "OKAY, WE'VE GOT ANOTHER LOW, "YOU KNOW, IT'S GOING TO BE FIVE OR TEN MINUTES BEFORE I CAN GET BACK TO SLEEP."

AND YOU GO UP THERE, YOU TEST HIM, YOU TREAT HIM, THEN GO BACK TO BED, BECAUSE IF HE GOES LOW AGAIN WE'RE GOING TO GET WOKE UP AGAIN.

Abraham: WITH DELTA AS HIS CONSTANT COMPANION, JOSEPH CAN ENJOY HIS FREEDOM, AND DIABETES NO LONGER RULES HIS LIFE.

Boy: SHE HAS GIVEN ME BACK MY LIFE, PRETTY MUCH.

USED TO, I DID NOT GO TO FRIENDS' OR HAVE FRIENDS OVER, BECAUSE I WAS TOO SCARED OF HAVING A SEIZURE IN FRONT OF THEM OR SOMETHING.

AND NOW THAT I HAVE A SERVICE DOG THAT I CAN DEPEND ON AND KNOW THAT SHE'LL KEEP ME SAFE, I CAN DO ALL THOSE THINGS NOW.

COME ON, DELTA.

Abraham: WHETHER DETECTING DISEASES LIKE EPILEPSY, DIABETES, AND CANCER, OR PROVIDING SUPPORT AND COMPANIONSHIP TO PEOPLE SUFFERING FROM MENTAL ILLNESS, DELTA REPRESENTS ONE OF MANY BREEDS THAT HAVE ADAPTED TO WORKING WITH US IN THE MODERN WORLD.

Hancock: IF YOU TAKE THE GERMAN SHEPHERD DOG -- STARTED OFF AS A SHEEP DOG, AS ITS NAME IMPLIES.

BECAUSE THEY WERE CAPABLE DOGS, THEY MOVED ON, AND THEY BECAME SERVICE DOGS, FIRST FOR THE GERMAN ARMY IN THE FIRST WORLD WAR, AND THEN WIDELY THROUGH MANY POLICE FORCES.

THEIR NOSES ARE EXTRAORDINARILY ADAPTABLE TO HUMAN REQUIREMENTS AND HUMAN NEEDS.

GOOD GIRL.

Abraham: IT'S NOT JUST DOGS WITH PEDIGREES THAT CAN SAVE LIVES.

THROUGHOUT HISTORY, THERE ARE EXTENSIVE RECORDS OF ALL KINDS OF DOGS WITH THE ABILITY TO ALERT US TO NATURAL DISASTERS.

Hancock: LOCAL PEOPLE IN SOUTHEAST ASIA DETECTED CONSIDERABLE AGITATION IN THEIR CANINE PETS BEFORE THE TSUNAMI.

DOGS HAVE THIS SIXTH SENSE.

THIS SIXTH SENSE ENABLES A DOG TO KNOW WHAT'S HAPPENING LONG BEFORE MAN CAN DETECT IT -- WHETHER YOU CAN GET OUT OF THE WAY OF A TSUNAMI IN TIME, WHETHER YOU CAN TAKE PRECAUTIONS IF A HURRICANE IS APPROACHING OR YOU CAN TAKE SOME KIND OF PROTECTIVE MEASURES IF AN EARTHQUAKE IS ABOUT TO HAPPEN, THIS IS IMMENSELY VALUABLE TO MAN.

Abraham: THE DOG'S EXTRAORDINARY SENSES HAVE ALREADY BEEN USED BY SCIENTISTS IN CHINA TO HELP SUCCESSFULLY PREDICT EARTHQUAKES.

WHEREVER WE ARE IN THE WORLD, IT'S THE DOG'S INTELLIGENCE AND ABILITY TO COMMUNICATE WITH US THAT SETS IT APART FROM OTHER DOMESTIC SPECIES, FROM PETS TO FARM ANIMALS.

Serpell: WE ARE REALLY PARASITES ON MOST OF OUR DOMESTIC ANIMALS.

WE FEED OFF THEM, FOR THE MOST PART.

BUT THE DOG HAS BECOME THIS KIND OF SYMBIOTIC PARTNER WITH US.

IT HAS BECOME LIKE ANOTHER LIMB, AN EXTENSION OF OURSELVES.

[ CHIRPS ] Abraham: THE CLOSE RELATIONSHIP BETWEEN MAN AND DOG HAS A LONG HISTORY.

BUT AFTER 15,000 YEARS, WE ARE STARTING A NEW CHAPTER.

FROM DIAGNOSIS TO DISASTER PREDICTION, SCIENTISTS ARE JUST BEGINNING TO UNDERSTAND THE NEW WAYS IN WHICH DOGS CAN CONTINUE TO CHANGE THE WORLD.

WHATEVER WE FACE IN THE FUTURE, ONE THING IS CERTAIN.

THERE WILL ALWAYS BE A DOG AT OUR SIDE TO PROTECT AND ENRICH OUR LIVES.

DOWN.