NARRATOR: TODAY, WE HAVE EUROPE TO OURSELVES.

WE ARE ALL MODERN HUMANS.

BUT WHEN WE FIRST ARRIVED IN THIS LAND, IT WAS ALREADY A HOME FOR OUR COUSINS-- THE NEANDERTHALS.

WE USED TO THINK WE WERE SO MUCH MORE ADVANCED THAT WE KILLED THEM OFF, BUT THAT MAY BE WRONG.

IN REALITY, WE WERE SO SIMILAR, WE COULD INTERBREED WITH THEM AND SHARE OUR DNA.

MAN: THE OLD STORY HAS COLLAPSED, AND WE'VE GOT TO BEGIN TO TELL A NEW STORY ABOUT NEANDERTHALS AND MODERN HUMANS.

DIFFERENT MAN: THE POWER OF GENETICS IS THAT THE DATA WILL STARE YOU IN THE FACE AND FORCE YOU TO RETHINK YOUR IDEAS.

WOMAN: NEANDERTHALS HAVE A BAD REPUTATION OF BEING PERHAPS SOMEHOW STUPID, BUT THIS IS NOT TRUE.

NARRATOR: SO WHY DID WE WIN OUT WHILE THEY WENT EXTINCT?

THIS IS THE STORY OF OUR ANCESTORS AS THEY SPREAD TO EVERY CONTINENT OF THE WORLD.

WHAT WAS THE SECRET TO THEIR SUCCESS?

THEIR STORY IS OUR STORY.

NARRATOR: EASTERN EUROPE, 40,000 YEARS AGO.

TWO YOUNG MEN OUT HUNTING.

THEY'RE AS SMART AS ANY MODERN-DAY HUNTER...

BUT THEY'RE VULNERABLE-- NEWCOMERS IN A COLD NORTHERN LAND.

THESE ARE THE FIRST MODERN HUMANS WE KNOW OF ANYWHERE IN EUROPE.

40,000 YEARS LATER, THEIR REMAINS HAVE TURNED UP IN THE FORESTS OF ROMANIA AT PESTERA CU OASE-- THE CAVE OF BONES.

THEY WERE EXCAVATED BY PORTUGUESE ARCHAEOLOGIST JOAO ZILHAO.

IN 2002, ROMANIAN CAVERS CHANCED UPON A NEW CHAMBER DEEP INSIDE THE CAVE.

IT WAS AN ARCHAEOLOGIST'S DREAM, BUT GETTING TO IT WAS A NIGHTMARE.

MAN: PEOPLE TALK ABOUT EXTREME ARCHAEOLOGY.

I OFTEN THINK TO MYSELF, THERE'S TWO KINDS OF IT-- THERE'S THE HOLLYWOOD KIND, AND THERE'S THE REAL THING.

AND THE REAL THING IS RIGHT THERE.

NARRATOR: EVERY DAY, ZILHAO AND HIS TEAM HAD TO DIVE THROUGH AN UNDERWATER RIVER...

CLIMB DEEPER INTO THE CAVE... AND SQUEEZE THROUGH THE NARROWEST OF GAPS.

ZILHAO: YOUR BODY FITS BUT BARELY.

AND AS YOU, YOU KNOW, PULL YOURSELF OUT AND START LOOKING AROUND, IT'S-- IT'S FULL OF CAVE BEAR BONES ALL OVER THE PLACE, AND IT'S AMAZING.

NARRATOR: THIS WAS CLEARLY A PLACE WHERE PREHISTORIC BEARS HAD HIBERNATED.

THE ARCHAEOLOGISTS STARTED LOGGING EACH BONE.

ZILHAO: THE TEMPERATURE IS ABOUT 12 DEGREES.

THERE'S 100% HUMIDITY, AND IT'S DRIPPING ON TOP OF YOU CONSTANTLY, SO IT--IT'S NOT PLEASANT.

ZILHAO: YOU SEE ALL THESE BONES HERE?

NARRATOR: TWO WEEKS IN, THEY FOUND SOMETHING THAT WASN'T CAVE BEAR.

ZILHAO: THAT-- THAT LOOKS LIKE HUMAN OVER THERE.

YEP.

YEAH.

WHAT ELSE CAN IT BE?

AND ONE DAY, THERE YOU GO.

YOU KNOW, IT'S THE OCCIPITAL-- THE BACK OF THE SKULL.

YOU READ ABOUT HUMAN EVOLUTION, BUT IT'S ONE THING TO READ ABOUT THIS STUFF.

IT'S A DIFFERENT THING TO ACTUALLY HAVE THE EVIDENCE IN YOUR HANDS.

NARRATOR: IT WAS THE SKULL OF A TEENAGER WHO LIVED 40,000 YEARS AGO.

NEARBY, THEY FOUND THE JAWBONE OF ANOTHER YOUNG ADULT FROM THE SAME PERIOD.

HOW HAD THESE BONES GOTTEN INTO THE CAVE?

THERE WAS NO SIGN THE BODIES HAD BEEN DRAGGED IN BY A BEAR, BUT ALSO NO SIGN THE CAVE HAD BEEN USED AS A HOME BY PREHISTORIC PEOPLE.

WE FOUND NOTHING-- NO ARTIFACTS, NO CHARCOAL, NO FEATURES-- SO WE CONCLUDE THAT PEOPLE DID NOT LIVE IN THIS CAVE.

THE BODIES WERE NOT BURIED IN THIS CAVE.

THEY MUST HAVE BEEN WASHED IN.

NARRATOR: ZILHAO HAS AN INTRIGUING EXPLANATION FOR WHAT HE THINKS HAPPENED.

ZILHAO: IMAGINE TWO HUNTERS-- YOUNG ADULT OR LATE ADOLESCENT.

THEY'RE GOING OUT INTO THE MOUNTAINS TO HUNT.

ALL OF A SUDDEN, THERE'S A PROBLEM.

COULD HAVE BEEN A STORM.

[THUNDER] THEY HAVE AN ACCIDENT.

THEY FALL, AND THEY DIE.

THEN SNOW COVERS THE BODIES.

THEY GET FROZEN AND STAY THERE.

THEY'RE NOT EATEN BY SCAVENGERS.

THE BODIES ARE JUST PRESERVED IN THE SNOW.

END OF WINTER, COMES SPRING, WATER MELTS.

YOU HAVE THESE RUSHES OF MELTWATER, VERY POWERFUL.

EVERYTHING THAT WAS IN THE SNOW IS DRAGGED INTO THE SINKHOLES THAT EXIST ALL OVER THIS PLATEAU, AND THAT'S HOW THE BODIES END UP IN THE CAVE.

THEY JUST STAY THERE THOUSANDS AND THOUSANDS OF YEARS UNTIL WE COME AND DIG THEM UP.

NARRATOR: THESE UNFORTUNATE HUNTERS DIED 40,000 YEARS AGO.

THEY ARE THE OLDEST DEFINITIVELY MODERN HUMANS-- HOMO SAPIENS-- FOUND ANYWHERE IN EUROPE.

BUT THEY WERE NOT THE FIRST HUMANS TO CALL EUROPE THEIR HOME.

IN 1856, AN UNUSUAL SKELETON WAS DISCOVERED IN GERMANY IN THE NEANDER VALLEY.

IT BECAME KNOWN AS A NEANDERTHAL.

STOCKIER THAN MODERN HUMANS, WITH A BARREL CHEST AND SUPERSTRONG MUSCLE ATTACHMENTS, NEANDERTHALS HAVE FASCINATED US EVER SINCE.

AT FIRST, THEY WERE DISMISSED AS WILD, SIMPLEMINDED CAVEMEN, BUT NOW WE KNOW BETTER.

WOMAN: IF YOU LOOK AT THE NEANDERTHAL SKULL, YOU WILL NOTICE THAT IT'S ACTUALLY RATHER LARGE.

IT'S A VERY PRONOUNCED BROWRIDGE, DOUBLY ARCHED ABOVE THE EYE SOCKETS.

WE SEE A VERY PROJECTING NOSE WITH A VERY BIG NASAL OPENING.

NOT ONLY THE FACE IS LARGE, BUT ALSO THE BRAINCASE IS LARGE, AND THIS IS BECAUSE NEANDERTHAL BRAINS ARE LARGER THAN THE AVERAGE MODERN HUMAN BRAIN.

AND THIS IS PERHAPS SURPRISING BECAUSE NEANDERTHALS HAVE A BAD REPUTATION OF BEING PERHAPS SOMEHOW STUPID, BUT THIS IS NOT TRUE.

THIS DOESN'T MEAN THAT THEY WOULD HAVE HAD THE EXACT SAME COGNITIVE PROPERTIES AS WE DO, BUT CERTAINLY THEY WERE, UH, VERY SIMILAR IN MANY RESPECTS.

NARRATOR: IN THE HUMAN FAMILY TREE, NEANDERTHALS ARE OUR CLOSEST COUSINS.

HALF A MILLION YEARS AGO, THEIR ANCESTORS WERE THE SAME AS OURS.

BUT THEY MOVED OUT OF AFRICA EARLIER, INTO EUROPE AND CENTRAL ASIA.

THERE, THEY ADAPTED TO A COLDER CLIMATE AND EVOLVED INTO A DIFFERENT SPECIES-- NOT HOMO SAPIENS LIKE US, BUT HOMO NEANDERTHALENSIS... NEANDERTHALS.

THEY MADE ICE-AGE EUROPE THEIR HOME, LIVING IN SMALL GROUPS, HUNTING BIG GAME.

SO WHAT HAPPENED WHEN MODERN HUMANS TURNED UP 40,000 YEARS AGO?

WHAT DID WE MAKE OF THE NEANDERTHALS?

IT'S LONG BEEN THOUGHT WE WERE SO SUPERIOR, WE SIMPLY WIPED THEM OUT.

ARCKA!

ARCKA!

[PEOPLE SHOUTING INDISTINCTLY] NARRATOR: BUT IS THIS REALLY TRUE?

THE REMAINS THAT JOAO ZILHAO FOUND IN ROMANIA TELL A DIFFERENT STORY.

THEY HAVE THE FEATURES OF A MODERN HUMAN-- THE SMALL VERTICAL FACE AND JUTTING CHIN THAT FIRST APPEARED IN AFRICA 200,000 YEARS AGO-- BUT ALL IS NOT WHAT IT SEEMS.

ZILHAO: WHEN YOU LOOK AT THIS SKULL, IT IS OBVIOUSLY MODERN.

ON THE OTHER HAND, WHEN YOU LOOK MORE CLOSELY, SOME THINGS ARE NOT QUITE RIGHT FOR A MODERN HUMAN.

UH, FOR INSTANCE, THE FRONTAL BONE SLOPES BACKWARD VERY MARKEDLY.

THE DENTITION IN PARTICULAR IS VERY STRANGE.

THE FIRST MOLAR IS SMALLER THAN THE SECOND.

THE SECOND IS SMALLER THAN THE THIRD.

THESE ARE FEATURES THAT YOU WOULD NOT EXPECT TO FIND IN A--IN A MODERN HUMAN.

WHERE YOU DO FIND SUCH FEATURES IS AMONG THE NEANDERTHALS.

NARRATOR: INSTEAD OF WIPING OUT THE NEANDERTHALS, ZILHAO BELIEVES WE MATED WITH THEM, AND THE TWO PEOPLES INTERBRED.

ZILHAO: WE CALL THESE PEOPLE NEANDERTHAL AND MODERN HUMAN.

THEY WOULD NOT KNOW THEY WERE NEANDERTHAL OR MODERN HUMAN.

WE HAVE TO THINK ABOUT WHAT IS LOGICAL IN A CONTEST LIKE THIS.

PEOPLE HAVE SEX, AND PEOPLE BREED.

IT'S JUST, UH-- THAT'S BASIC HUMAN NATURE.

NARRATOR: ACCORDING TO ZILHAO, THE SKULL IS A HUMAN HYBRID-- PART MODERN, PART NEANDERTHAL.

UNTIL RECENTLY, THE IDEA THAT TWO DISTINCT HUMAN SPECIES COULD INTERBREED AND HYBRIDIZE WAS THOUGHT TO BE IMPOSSIBLE-- A SCIENTIFIC HERESY.

THAT'S CHANGED, THANKS TO DNA.

THE MAX PLANCK INSTITUTE IS A LEADER IN THE STUDY OF ANCIENT DNA.

IN 2010, THEY WERE THE FIRST PEOPLE TO CRACK THE GENETIC CODE OF A NEANDERTHAL.

THE FIRST CHALLENGE WAS TO FIND THE RIGHT BONE WHICH STILL CONTAINED READABLE DNA AFTER 38,000 YEARS IN A CAVE.

THEN THEY HAD TO SEQUENCE THE DNA, ANALYZING EVERY FRAGMENT.

IT WAS LIKE TRYING TO READ A BOOK THAT'S BEEN RIPPED INTO MILLIONS OF PIECES.

THE PROJECT WAS LED BY SWEDISH GENETICIST SVANTE PAABO.

MAN: IMAGINE THAT WHAT WE HAVE IN THIS BAG IS THE DNA WE HAVE EXTRACTED FROM A NEANDERTHAL BONE-- AND WE ILLUSTRATED THIS WITH AN AMERICAN DICTIONARY THAT WE HAVE SHREDDED.

BUT IT'S NOT ONLY THIS DICTIONARY HERE.

THERE ARE DICTIONARIES OF OTHER LANGUAGES THAT ILLUSTRATE THE GENOMES OF BACTERIA AND FUNGI THAT HAVE LIVED IN THE BONE OVER TENS OF THOUSANDS OF YEARS.

AND OUR CHALLENGE IS NOW TO TRY TO FIND THE PIECES THAT COME FROM THE NEANDERTHAL GENOMES AMONG ALL THESE MILLIONS AND MILLIONS OF OTHER PIECES THAT WE'RE NOT INTERESTED IN.

WHAT WE ARE FACED WITH IS NOT ONLY THAT WE HAVE A MIXTURE OF DIFFERENT GENOMES HERE.

THE PIECES ARE ALSO VERY SMALL, AND THEY GET SMALLER AND SMALLER AS TIME PASSES.

AND NOT ONLY THAT, THEY ARE IN ADDITION CHEMICALLY MODIFIED, WHICH WE CAN ILLUSTRATE WITH THIS.

NARRATOR: IMAGINE HAVING TO DECIPHER MILLIONS OF FRAGMENTS THAT ARE SO DEGRADED THEY'RE BARELY LEGIBLE AND THEN USING THEM TO RECONSTRUCT AN ENTIRE DICTIONARY.

IT SEEMS AN IMPOSSIBLE TASK, BUT THAT'S THE EQUIVALENT OF WHAT PAABO AND HIS TEAM HAD TO DO WITH THE NEANDERTHAL GENOME.

THEY HAD ONE THING GOING FOR THEM.

BECAUSE NEANDERTHALS ARE OUR COUSINS, THEIR GENOME WAS BOUND TO BE INCREDIBLY SIMILAR TO OURS-- WRITTEN IN MORE OR LESS THE SAME LANGUAGE.

MAN: WHAT WE DO IS COMPARE THESE TINY LITTLE DNA FRAGMENTS FROM THE NEANDERTHAL BONE TO THE GENOME OF PRESENT-DAY HUMANS.

AND WE EXPECT TO SEE JUST TINY DIFFERENCES, BECAUSE THE NEANDERTHALS ARE, OF COURSE, VERY CLOSELY RELATED, AFTER ALL, TO PRESENT-DAY PEOPLE-- AT LEAST 10 TIMES AS CLOSE AS A CHIMPANZEE, FOR EXAMPLE.

SO IN THIS ANALOGY HERE, ONE COULD SEE THIS AS A DIFFERENCE BETWEEN AMERICAN ENGLISH AND BRITISH ENGLISH, FOR EXAMPLE-- WHICH IS VERY, VERY SIMILAR, BUT HAVE TINY LITTLE DIFFERENCES IN HOW YOU SPELL WORDS.

NARRATOR: IT'S THESE SUBTLE DISCREPANCIES THAT EMBODY THE GENETIC DIFFERENCE BETWEEN NEANDERTHALS AND MODERN HUMANS.

IT TOOK THE SEQUENCING MACHINES 2 1/2 YEARS TO SIFT AND SORT THROUGH ALL THE FRAGMENTS AND CONSTRUCT A COMPLETE SEQUENCE...

BUT WHEN THE WORK WAS DONE, THEY HAD BEFORE THEM THE FIRST GENOME OF AN EXTINCT HUMAN.

MAN: ONE OF THE FIRST QUESTIONS WE WERE REALLY INTERESTED IN WAS WHAT HAPPENED WHEN MODERN HUMANS CAME OUT OF AFRICA AND MET NEANDERTHALS.

DID OUR ANCESTORS THEN MIX WITH NEANDERTHALS OR NOT?

NARRATOR: THEY COMPARED THE NEANDERTHAL GENOME WITH THAT OF MODERN-DAY PEOPLE FROM AROUND THE WORLD.

THEY DISCOVERED A REMARKABLE PATTERN.

IN AFRICA, THEY FOUND NO EVIDENCE OF INTERBREEDING...

BUT EVERYWHERE ELSE IN THE WORLD, THERE WAS A TRAIL OF NEANDERTHAL GENES.

BETWEEN 1% AND 3% OF OUR DNA HAS BEEN INHERITED FROM NEANDERTHALS.

PAABO: I WAS FIRST VERY SKEPTICAL WHEN WE STARTED SEEING THIS SIGNAL, BUT THE POWER OF GENETICS IS IN A WAY THAT THE DATA WILL STARE YOU IN THE FACE AND FORCE YOU TO RETHINK YOUR IDEAS IF YOU'RE WRONG.

NARRATOR: ACCORDING TO THE GENETICS, INTERBREEDING HAPPENED IN THE MIDDLE EAST.

AROUND 55,000 YEARS AGO, MODERN HUMANS WERE EXPANDING NORTH OUT OF AFRICA.

AT THE SAME TIME, THE NEANDERTHALS WERE BEING PUSHED SOUTH BY A COLD SPELL IN EUROPE.

THE TWO TYPES OF HUMAN WERE DESTINED TO MEET.

AND HERE THEY MATED AND INTERBRED.

THE GENETIC EVIDENCE UNDERMINES THE TRADITIONAL VIEW OF EUROPE'S FIRST PEOPLES.

IF THEY BRED WITH EACH OTHER, THE TWO TYPES OF HUMAN CANNOT HAVE BEEN SO VERY DIFFERENT.

MAN: FOR A CENTURY AND A HALF, SCIENTISTS HAVE BEEN PICKING OVER THE EVIDENCE IN EUROPE, TRYING TO UNDERSTAND WHY NEANDERTHALS SEEM SO SEPARATE FROM US.

THEY ASSUMED THAT MODERN HUMANS ARE JUST SUPERIOR TO NEANDERTHALS, AND SO THERE'D BE NO CHANCE OF THEM INTERACTING WITH EACH OTHER IN ANY MEANINGFUL WAY.

NOW GENETICS IS SHOWING US THAT THAT'S WRONG-- THAT THESE TWO TYPES OF HUMANS INTERBRED WITH EACH OTHER.

THAT MAY CHANGE EVERYTHING.

WE'VE GOT TO FIND A WAY TO FIT NEANDERTHALS INTO THIS STORY.

THEY'RE LIKE CARDS FROM A DIFFERENT PACK-- SIMILAR, BUT DIFFERENT.

THE PROBLEM IS, IF WE TRY TO PUT THEM IN THIS STRUCTURE, THE WHOLE THING MAY COME TUMBLING DOWN.

TO ME, AS AN ANTHROPOLOGIST, THAT'S WHAT IT FEELS LIKE AT THE MOMENT.

THE OLD STORY HAS COLLAPSED, AND WE'VE GOT TO BEGIN TO TELL A NEW STORY ABOUT NEANDERTHALS AND MODERN HUMANS-- A STORY ABOUT INTERACTION.

NARRATOR: THE NEW STORY STARTS HERE IN SOUTHERN FRANCE, WITH A REMARKABLE DISCOVERY WHICH SUGGESTS MODERN HUMANS WERE IN EUROPE FAR EARLIER THAN ANYONE THOUGHT.

[MAN SPEAKING FRENCH] NARRATOR: THIS IS MANDRIN CAVE.

ARCHAEOLOGIST LUDOVIC SLIMAK HAS BEEN EXCAVATING HERE FOR 10 YEARS.

[SPEAKING FRENCH] TRANSLATOR: MANDRIN CAVE WAS DISCOVERED RECENTLY AND HAS EXCEPTIONAL PRESERVATION.

MODERN ARCHAEOLOGICAL METHODS DEVELOPED HERE GIVE US A VERY PRECISE PICTURE OF THE LIVES OF THE DIFFERENT HUMAN GROUPS WHO CAME TO MANDRIN CAVE.

NARRATOR: AS HIS TEAM EXCAVATED, THEY UNCOVERED A MASS OF ARTIFACTS IN SEDIMENT THAT'S 50,000 YEARS OLD.

[SLIMAK SPEAKING FRENCH] TRANSLATOR: BELOW THE GRAY LAYER, IN THE MIDDLE THERE, YOU CAN SEE A KIND OF YELLOW SAND.

AND THIS LAYER HAS REVEALED SOMETHING SURPRISING WHICH WE'VE NEVER SEEN IN EUROPE BEFORE.

NARRATOR: IN THIS ONE LAYER WERE MORE THAN 1,000 TINY SHARDS OF FLINT.

[SLIMAK SPEAKING FRENCH] TRANSLATOR: THIS ONE IS A PERFECT TRIANGLE.

IT'S JUST A CENTIMETER LONG.

AND THIS POINT HAS A FRACTURE, WHICH I THINK MUST HAVE BEEN CAUSED BY ITS USE AS A WEAPON.

WE KNOW BLADES LIKE THIS EXIST IN TRADITIONAL TRIBES TODAY, BUT THEY ARE ALWAYS PROPELLED BY A BOW, WHICH WILL MEAN THAT THESE ARE ARROWHEADS.

NARRATOR: THE BOW AND ARROW IS A WEAPON ASSOCIATED ONLY WITH MODERN HUMANS.

DOES THIS MEAN THEY WERE IN FRANCE 50,000 YEARS AGO-- 10,000 YEARS BEFORE WE FIND THEM IN ROMANIA?

SLIMAK HAS TO BE SURE THE OBJECTS REALLY ARE ARROWHEADS, SO HE SETS ABOUT REPLICATING THEM.

[SLIMAK SPEAKING FRENCH] TRANSLATOR: THE SORT OF POINT FOUND AT MANDRIN REQUIRES A VERY HIGH LEVEL OF SKILL AND LOTS OF EXPERIENCE TO MAKE.

IT'S NOT ABOUT HITTING A ROCK AGAINST A ROCK.

IT'S ABOUT BECOMING IN TUNE WITH THAT ROCK.

THERE WOULD HAVE BEEN ONLY A FEW GREAT CRAFTSMEN WHO WOULD HAVE BEEN ABLE TO MAKE THEM.

WE ARE GOING TO CHIP OFF SOME SMALL PIECES TO GIVE THE BLOCK A PERFECT TRIANGULAR SHAPE.

WE CAN THEN MAKE IN ONE GO A POINT THAT'S IDENTICAL TO THE ONES FOUND IN MANDRIN CAVE.

NARRATOR: TO COMPLETE THE TEST, HE NEEDS TO FIRE THE ARROWHEADS AND SEE IF THEY FRACTURE IN THE SAME WAY AS THE POINTS FROM THE CAVE.

THAT REQUIRES AN EXPERT ARCHER AND A SUITABLE PREY.

[PEOPLE SPEAKING FRENCH] IT'S PERFECT.

[SPEAKING FRENCH] [SLIMAK SPEAKING FRENCH] C'EST BIEN.

IT'S A GOOD ONE.

NARRATOR: SINCE MODERN HUMANS WERE THE ONES MAKING ARROWHEADS, SLIMAK BELIEVES THEY MUST HAVE BEEN HERE 50,000 YEARS AGO.

[SLIMAK SPEAKING FRENCH] TRANSLATOR: TODAY, THE RHONE IS A MAJOR HIGHWAY.

BOATS, TRAINS, AND CARS USE IT TO GET FROM THE MEDITERRANEAN TO THE NORTH.

THIS HIGHWAY MUST HAVE BEEN THE SAME IN THE PAST.

YOU CAN IMAGINE SEEING BIG HERDS OF HORSES AND BISON COMING UP FROM THE MEDITERRANEAN.

THEY MUST HAVE BEEN A GREAT RESOURCE FOR THE HUNTERS WHO WERE IN THIS POPULATION 50,000 YEARS AGO.

NARRATOR: BUT MODERN HUMANS WERE NOT THE ONLY PEOPLE USING THIS HUNTING GROUND.

WHAT'S INTRIGUING IS, THE ARROWHEADS WERE FOUND IN A LAYER SANDWICHED BETWEEN OTHER LAYERS OF ARTIFACTS MADE BY NEANDERTHALS.

BASED ON FRAGMENTS OF SOOT IN THE SAME SEDIMENT, THE GAP BETWEEN THESE LAYERS WAS INCREDIBLY SMALL.

[SPEAKING FRENCH] TRANSLATOR: ANALYZING WITH SOOT DEPOSIT, WE CAN SEE THE TIME BETWEEN TWO OCCUPATIONS AT MANDRIN CAVE, AND THEREFORE WE KNOW THAT BETWEEN THE PEOPLE WHO MADE NEANDERTHAL TOOLS IN THIS CAVE AND THE PEOPLE WHO MADE THE BOW AND ARROWS, IT WAS ONLY A VERY SHORT TIME-- MAYBE ONE SEASON, MAYBE TWO.

NARRATOR: THE PICTURE THAT EMERGES IS OF MODERN HUMANS IN THE RHONE VALLEY 50,000 YEARS AGO.

THEY SHOW UP HERE BEFORE ANYWHERE ELSE IN EUROPE.

THEY WERE USING BOW AND ARROWS TO HUNT THEIR PREY.

BUT THEY DIDN'T STAY LONG.

FOR SOME REASON, THEY MOVED ON, NOT TO RETURN FOR THOUSANDS OF YEARS.

AND WITHIN MONTHS, OR JUST WEEKS, THE NEANDERTHALS MOVED BACK IN.

THERE'S NO SIGN OF CONFRONTATION.

IT'S AS IF THE TWO TYPES OF HUMAN WERE MOVING IN AND OUT OF EACH OTHER'S TERRITORY AS EQUALS.

NEANDERTHALS MAY NOT HAVE MADE ARROWHEADS, BUT AT EXACTLY THE SAME TIME, THEY WERE MAKING TOOLS JUST AS INGENIOUS AS THOSE MADE BY MODERN HUMANS.

300 MILES FROM THE RHONE, AT ABRI PEYRONY ROCK SHELTER, ARCHAEOLOGIST SHANNON McPHERRON HAS EXCAVATED PART OF A BONE.

MAN: IT'S A SMALL FRAGMENT OF RIB, WITH THIS CURVED POLISHED TIP, THAT I THINK IS THE BROKEN END OF A BONE TOOL.

WHEN--WHEN WE LOOK AT THIS IN A MICROSCOPE, WE SEE SMALL GROOVES, SMALL STRIATIONS THAT SHOW THE DIRECTION OF USE, THAT SHOW THAT IT WAS GETTING RUBBED UP AGAINST SOMETHING.

[HORSE NEIGHS] NARRATOR: AS McPHERRON WONDERED WHAT THESE BONE TOOLS WERE FOR, HE REALIZED LEATHER WORKERS TODAY USE SOMETHING SIMILAR.

DELPHINE VIAU IS A SADDLE MAKER WORKING IN A TRADITIONAL WAY.

SHE IMMEDIATELY RECOGNIZES THE TOOL.

[SPEAKING FRENCH] TRANSLATOR: THEY ARE LISSOIRS.

THIS ONE IS SMALLER, BUT IT'S THE SAME THING.

[SPEAKING FRENCH] TRANSLATOR: SO YOU'RE USING THE EDGES OF THE TOOL?

[SPEAKING FRENCH] TRANSLATOR: YOU CLOSE ALL THE PORES OF THE SKIN, WHICH MAKES IT WATERPROOF.

NOW IT'S CLOSED.

YOU CAN ALSO IMAGINE IF YOU USE OIL ON IT, IT WILL PENETRATE REALLY DEEPLY.

[SPEAKING FRENCH] TRANSLATOR: WHY USE BONE AND NOT WOOD?

[SPEAKING FRENCH] TRANSLATOR: IT CAN BE DONE WITH WOOD OR METAL, BUT METAL SCRATCHES EASILY.

THERE IS A RISK THAT SOMETHING COULD DAMAGE THE LEATHER.

AND WOOD WEARS OUT, UNLIKE BONE, WHICH IS INDESTRUCTIBLE.

NARRATOR: 50,000 YEARS AGO, THIS IS WHAT NEANDERTHALS WERE DOING-- USING A RIB BONE AS A LISSOIR TO MAKE THEIR SKINS WATERPROOF-- A CREATIVE RESPONSE TO THE WET, COLD CONDITIONS OF ICE-AGE EUROPE.

McPHERRON: IT DOES SHOW ON THE PART OF THE NEANDERTHALS AN ABILITY TO SOLVE A PROBLEM THAT LET THEM PREPARE THEIR HIDES BETTER.

WHAT I FIND COOL IN THIS CASE IS THAT WE HAVE SOMETHING THAT BRIDGES THAT 50,000 YEARS BETWEEN US AND THEM.

IN THIS CASE, IT'S THE SAME TOOL BEING USED ACROSS ALL THAT TIME.

NARRATOR: JOAO ZILHAO THINKS NEANDERTHALS HAD TALENTS THAT WENT BEYOND TOOL MAKING.

THEY ALSO HAD AN AESTHETIC SENSE.

THEY WERE CAPABLE OF SYMBOLIC THOUGHT-- USING SHELLS TO MIX UP NATURAL PIGMENTS.

ZILHAO: THERE ARE SEVERAL POSSIBILITIES TO EXPLAIN THIS.

ONE IS THAT, UH, THEY PAINTED THE SHELL.

THEY WANTED IT TO BE A DIFFERENT COLOR FROM THE ORIGINAL.

THE OTHER IS THAT THEY WERE USING THE SHELL AS A CONTAINER FOR SOMETHING LIKE BODY PAINTING OR MAKEUP.

IN SOCIETIES THAT LACK IDENTITY CARDS OR PASSPORTS, UM, BODY PAINTING AND PERSONAL ORNAMENTATION, UH, TRANSMIT INFORMATION ABOUT WHO YOU ARE.

IT'S A WAY OF CONVEYING A MESSAGE, UH, OF-- ABOUT THEMSELVES-- WHICH TRIBE YOU BELONG TO, WHETHER YOU'RE OUT TO PARTICIPATE IN HUNTING.

IN A WAY, YOU CAN SAY THAT THIS IS MODERN BEHAVIOR, AND SINCE WE HAVE DOCUMENTED IT AMONG THE NEANDERTHALS, THE CONCLUSION IS THAT NEANDERTHALS WERE MODERN, TOO.

THAT WOULD BE MY CONCLUSION.

[SHOUTS INDISTINCTLY] [SHOUTS INDISTINCTLY] NARRATOR: WHAT ELSE WERE THE NEANDERTHALS CAPABLE OF?

JUST HOW SIMILAR TO US WERE THEY?

JEAN-JACQUES HUBLIN IS AN EXPERT ON A LAYER OF ARTIFACTS-- KNOWN AS THE CHATELPERRONIAN-- FROM THE EARLY DAYS OF CONTACT.

MAN: THIS IS A TOOTH OF FOX THAT IS PIERCED HERE, AND WE IMAGINE VERY EASILY HOW THIS COULD BE A PART OF A--A NECKLACE OR HOW IT COULD BE FIXED ON A PIECE OF, UH, CLOTHES, FOR EXAMPLE.

AND CLEARLY THIS SPEAKS TO US, BECAUSE THIS IS EXACTLY THE KIND OF TECHNIQUE THAT HAS BEEN USED BY RECENT HUNTER-GATHERERS AND EVEN TODAY.

NARRATOR: ARCHAEOLOGISTS ALWAYS THOUGHT OF JEWELRY AS THE WORK OF MODERN HUMANS, BUT WHEN THEY DISCOVERED THE TEETH OF THE PEOPLE WHO MADE THE ARTIFACTS...

THEY WERE NEANDERTHAL.

HUBLIN: THE TEETH FROM THE CHATELPERRONIAN LAYERS ARE TYPICAL FROM WHAT WE FIND IN NEANDERTHAL, UH, DENTITION EVERYWHERE ELSE.

YOU CAN SEE HERE THE DIFFERENCE BETWEEN A NEANDERTHAL UPPER INCISOR AND A MODERN HUMAN UPPER INCISOR.

THERE'S A DIFFERENCE IN SIZE.

THERE'S ALSO A DIFFERENCE IN--IN SHAPE.

IN NEANDERTHALS, YOU HAVE WHAT WE CALL A-- A SHOVEL SHAPE OF-- OF THIS TOOTH THAT YOU DON'T HAVE AT ALL IN MOST MODERN HUMANS.

NARRATOR: IF NEANDERTHALS WERE MAKING SOME OF THE FIRST NECKLACES IN EUROPE, WHAT DOES THIS SAY ABOUT THEM AND THEIR ABILITIES?

ZILHAO: FOR--FOR DECADES, SCIENCE HAS BEEN ASKING ITSELF THE QUESTION OF WHETHER NEANDERTHALS COULD OR COULD NOT, UH, MAKE THESE KINDS OF THINGS AS A CLUE TO WHETHER THEIR COGNITION WAS LIKE OUR OWN.

IT HAS BECOME CLEAR FROM THE ARCHAEOLOGICAL RECORD THAT THEY COULD DO THESE THINGS.

WE KNOW THEY COULD, BECAUSE THEY DID DO THESE THINGS.

NARRATOR: IT SEEMS NEANDERTHALS WERE NOT THE DUMB BRUTES OF LEGEND.

ISOLATED IN EUROPE FOR TENS OF THOUSANDS OF YEARS, THEY HAD DEVELOPED THEIR OWN CULTURE ON A PAR WITH THAT OF THEIR MODERN HUMAN COUSINS.

BUT ALL THE WHILE, MODERN HUMANS CONTINUED PUSHING OUT OF AFRICA, THROUGH THE MIDDLE EAST, AND INTO EUROPE.

CHANGE WAS COMING.

WITHIN THE CHATELPERRONIAN LAYER, ARCHAEOLOGISTS FIND A TYPE OF SPEAR POINT MADE BY NEANDERTHALS WHICH LOOKS INCREDIBLY SIMILAR TO POINTS MADE AT THE SAME TIME BY MODERN HUMANS.

IT'S AS IF THE NEANDERTHALS WERE COPYING THE DESIGN.

THEY MAY NEVER HAVE MET THE PEOPLE WHO MADE THE ORIGINALS.

ALL THEY NEEDED WAS TO FIND A DISCARDED SPEAR AND WORK OUT FOR THEMSELVES HOW TO MAKE IT.

HUBLIN: IT LOOKS LIKE THEY HAVE PRODUCED THE SAME KIND OF OBJECT, BUT WITH THEIR OWN TECHNOLOGY.

SO THE FINAL PRODUCT LOOKS VERY MUCH THE SAME, BUT THE METHOD TO PRODUCE IT IS DIFFERENT.

NARRATOR: TO COPY A TECHNOLOGY WITHOUT AN INSTRUCTION MANUAL IS A SIGN OF INTELLIGENCE, BUT IT ALSO SPELLED THE BEGINNING OF THE END FOR THE NEANDERTHALS.

THEY WERE NOW PLAYING CATCH-UP, THEIR CULTURE TRANSFORMED BY THE PRESENCE OF MODERN HUMANS.

HUBLIN: SOME HAVE ARGUED THAT NEANDERTHALS INVENTED THESE KIND OF OBJECTS INDEPENDENTLY FROM THE MODERN HUMANS, BUT IT'S KIND OF PUZZLING THAT THEY WOULD DO THAT JUST AT THE MOMENT WHEN MODERN HUMANS MOVED INTO EUROPE.

NARRATOR: SOMETHING SIMILAR HAPPENED 400 YEARS AGO WHEN EUROPEANS BROUGHT HORSES TO NORTH AMERICA.

THE NATIVE PEOPLE REALIZED HOW USEFUL THESE ANIMALS WERE AND LEARNED TO RIDE THEM WITHOUT EVER BEING TAUGHT BY EUROPEANS.

THE IDEA SPREAD SO QUICKLY AND SO EFFECTIVELY THAT HORSES BECAME CENTRAL TO THE CULTURE OF PLAINS INDIANS.

BUT NO MATTER HOW GOOD THEY WERE AT ADAPTING TO A NEW CULTURE, THEY COULDN'T KEEP UP-- OVERWHELMED BY THE SHEER NUMBER OF EUROPEANS MOVING ONTO THEIR LAND.

IN PREHISTORIC EUROPE, NEANDERTHALS FACED THE SAME SORT OF FATE-- OVERWHELMED BY THE SPREAD OF MODERN HUMANS.

HAWKS: AT FIRST, NEANDERTHALS AND MODERN HUMANS SEEM TO HAVE BEEN EQUAL PARTNERS.

THEY WERE SHARING THE LANDSCAPE, THEY WERE SHARING TECHNOLOGY, AND THEY WERE SHARING GENES.

IF YOU IMAGINE THAT THIS DECK OF CARDS IS MODERN HUMANS AND THIS DECK IS NEANDERTHALS, THEY'RE BASICALLY THE SAME, BUT THE NEANDERTHALS HAVE BLUE FACE CARDS, SO JUST A LITTLE BIT DIFFERENT.

IF WE MIX THEM TOGETHER, THAT'S WHAT WAS HAPPENING IN THE EUROPEAN LANDSCAPE.

AND YOU LOOK AT THE RESULTING BLEND OF POPULATIONS, YOU CAN SEE THAT THERE'S A GOOD MIX.

YOU'VE GOT A LOT OF ORDINARY CARDS AND A FEW OF THE BLUE CARDS.

BUT THEN, AT SOME POINT, THE BALANCE OF POWER SHIFTS.

NEANDERTHALS ARE STUCK IN EUROPE, BUT MODERN HUMAN POPULATIONS ARE GROWING IN AFRICA AND ASIA, AND YOU GET WAVE AFTER WAVE OF NEW POPULATIONS COMING INTO EUROPE.

AS THEY DO, IT'S LIKE MIXING IN MORE AND MORE OF THESE DECKS OF CARDS.

SO WHAT YOU END UP SEEING IS THAT THE POPULATION IS ALMOST UNIFORMLY MODERN HUMANS WITH JUST A LITTLE BIT OF NEANDERTHAL.

THAT MEANS THAT THE NEANDERTHALS WERE SWAMPED.

THEY WERE ABSORBED INTO THE MODERN HUMAN POPULATION GENETICALLY, PHYSIOLOGICALLY, AND CULTURALLY.

NARRATOR: ONE OF THE KEY ROUTES INTO EUROPE WAS VIA THE DANUBE RIVER.

IT FLOWS FROM THE BLACK SEA THROUGH EASTERN EUROPE INTO MODERN-DAY GERMANY.

1,000 MILES UPRIVER, IT PASSES THROUGH THE REGION OF SWABIA.

IN MODERN TIMES, THE RIVER HAS CHANGED COURSE, BUT 40,000 YEARS AGO, THIS WAS THE DANUBE VALLEY.

IT WAS HOME TO A NEW WAVE OF MODERN HUMANS SPREADING THROUGH EUROPE.

THEY LIVED IN LIMESTONE CAVES LIKE THIS ONE--HOHLE FELS.

FOR 17 YEARS, ARCHAEOLOGIST NICK CONARD HAS BEEN WORKING HERE-- DIRECTING EXCAVATIONS, EXPLORING THE HUMAN HISTORY OF THIS CAVE.

MAN: SO, JANE, MORE LITTLE TREASURES?

HAVE YOU BEEN FINDING BIRD BONE OR MAINLY, UM, CHARCOAL?

JANE: UH, A FEW VERY SMALL PIECES... NARRATOR: THEY FIND ARTIFACTS MADE BY NEANDERTHALS AND MODERN HUMANS, BUT NEVER FROM THE SAME DATE.

THERE'S A 2,000-YEAR GAP BETWEEN THE LAST NEANDERTHAL AND THE FIRST MODERN HUMAN.

A FASCINATING QUESTION IS, WHAT HAPPENED WHEN MODERN HUMANS ARRIVED?

WHAT WAS THE SITUATION?

WE WOULD EXPECT MODERN HUMANS AND NEANDERTHALS TO HAVE MET HERE.

INTERESTINGLY, THAT'S NOT THE CASE.

WHEN WE LOOK AT THE DEEP DEPOSITS AT HOHLE FELS, WE CAN SHOW THAT NEANDERTHALS WERE LIVING HERE FOR MANY THOUSANDS OF YEARS, BUT WHEN MODERN HUMANS ARRIVED, THE CAVE WAS EMPTY.

THAT RAISES A QUESTION OF, WHY WAS THAT THE CASE?

WHY WEREN'T NEANDERTHALS VISIBLY HERE ON THE LANDSCAPE WHEN MODERN HUMANS ARRIVED?

NARRATOR: CONARD BELIEVES THAT BY THE TIME THEY WERE HERE IN SWABIA, THE TWO TYPES OF HUMAN WERE ON A DIFFERENT TRAJECTORY.

JUDGING BY THE ARTIFACTS THEY MADE, MODERN HUMANS HAD TAKEN A QUANTUM LEAP FORWARD.

THE VENUS OF HOHLE FELS WAS MADE 35,000 TO 40,000 YEARS AGO.

IT'S THE OLDEST SCULPTURE OF A HUMAN BODY FOUND ANYWHERE IN THE WORLD.

CONARD: IT'S INTERESTING TO LOOK AT WHAT IS DEPICTED AND WHAT'S ABSENT.

WHAT IS MOST PROMINENTLY ABSENT IS THE HEAD.

THERE'S NO HEAD AT ALL.

INSTEAD OF A HEAD, THERE'S A RING, SHOWING THAT IT WAS USED PERHAPS AS AN ORNAMENT OR WORN AROUND THE NECK.

WHAT IS PRESENT ARE THE SEXUAL CHARACTERISTICS.

THE PUBIC TRIANGLE AND THE VULVA ARE VERY INTENSELY CUT OUT, SHOWING THAT THE GENITALIA OF REPRODUCTION WERE IMPORTANT.

THE BREASTS-- ENORMOUS BREASTS, OVERSIZED-- ALSO CONSISTENT WITH THE IDEA OF FERTILITY AND, UH, REPRODUCTION.

YOU CAN IMAGINE AFTER SPENDING MONTHS BEING HOLED UP TRYING TO SURVIVE THE LONG, COLD WINTER... AND THEN THE SPRING COMES.

THE GRASS COMES UP.

THE ANIMALS START TO HAVE SOMETHING TO EAT.

I MEAN, THE JOY WE HAVE AT THE END OF THE WINTER, IT WOULD BE NOTHING COMPARED TO THESE PEOPLE WHO'VE BEEN HUNKERING DOWN IN A CAVE JUST TRYING TO MANAGE OVER THOSE LONG MONTHS.

THE WHOLE IDEA OF THE CONNECTEDNESS BETWEEN PEOPLE, HUMAN REPRODUCTION, ANIMAL REPRODUCTION-- THAT ALL IS WHAT THIS, UH, FIGURINE'S ABOUT.

NARRATOR: IN NEIGHBORING CAVES, ARCHAEOLOGISTS HAVE FOUND OTHER FIGURINES CARVED FROM MAMMOTH IVORY...

ANIMALS THAT POPULATED THE ICE-AGE LANDSCAPE.

THEY ARE SOME OF THE MOST EXQUISITE ART OBJECTS EVER MADE-- THE CROWN JEWELS OF EUROPEAN ARCHAEOLOGY.

ONE OF THE MOST INTRIGUING FIGURES IS NEITHER ANIMAL NOR HUMAN...

BUT BOTH.

11 INCHES TALL, THE LION MAN OF HOHLENSTEIN STADEL IS THOUGHT TO BE SOME KIND OF RELIGIOUS ICON-- A SHAMANIC TOTEM.

BUT HE'S NOT ALONE.

A MINIATURE VERSION OF THE SAME FIGURE WAS FOUND AT HOHLE FELS 30 MILES AWAY.

CONARD: THE REMARKABLE THING ABOUT THE LION MEN IS THAT WE HAVE TWO OBJECTS THAT, ALTHOUGH THEY'RE A VERY DIFFERENT SIZE, ARE ACTUALLY THE SAME THING-- COMBINATIONS OF LIONS AND HUMANS BEING DEPICTED IN TWO DIFFERENT VALLEYS.

WHEN YOU FIND THE SECOND ONE, IT MAKES IT VERY CLEAR THAT THIS WAS PART OF THEIR IDEOLOGY, THEIR SYSTEM OF BELIEFS, SHOWING THAT THERE WAS INTERACTION BETWEEN THESE PEOPLE-- THAT THEY EXISTED IN A SOCIAL NETWORK, WERE FROM THE SAME CULTURE, SPOKE THE SAME LANGUAGE, PERHAPS EXCHANGING MATES, ECONOMIC TIES.

THEY LIVED ADJACENT TO ANOTHER BUT WERE IN FREQUENT CONTACT WITH ONE ANOTHER.

NARRATOR: ARCHAEOLOGISTS AT HOHLE FELS HAVE ALSO FOUND A BONE FLUTE.

MADE 35,000 YEARS AGO, IT'S ONE OF THE OLDEST MUSICAL INSTRUMENTS IN THE WORLD.

MAN: UH, THE BEST BONES TO MAKE FLUTES OF ARE WING BONES OF BIG BIRDS-- FOR EXAMPLE, VULTURES OR EAGLES OR SWANS.

IT'S THE SAME LIKE OUR LOWER ARM.

AND THE FIRST STEP TO MAKE A FLUTE OUT OF IT IS TO CUT OFF THE JOINT ENDS WITH A FLINT TOOL.

NARRATOR: WULF HEIN IS AN EXPERT IN PALEORECONSTRUCTIONS.

HE'S WORKED OUT IT WOULD HAVE TAKEN PREHISTORIC PEOPLE 4 HOURS TO MAKE A BONE FLUTE.

HEIN: ONE MAY WONDER, "WHY DID PEOPLE SPEND SO MUCH EFFORT ON MAKING A MUSICAL INSTRUMENT AT THAT TIME?"

AND FOR ME, THE ANSWER IS OBVIOUS.

MUSIC IS THE GLUE THAT KEEPS A SOCIETY TOGETHER.

IF YOU LIVE FOR A LONG TIME IN A SMALL SPACE WITH A LOT OF PEOPLE, THERE WILL BE AGGRESSION.

THERE WILL BE SOCIAL TENSION.

AND THE BEST THING TO KEEP THESE TENSIONS AWAY IS MAKING MUSIC.

NARRATOR: THE QUESTION IS, WHAT DID THE FLUTE SOUND LIKE?

[HEIN PLAYING "THE STAR-SPANGLED BANNER"] JIMI HENDRIX DID IT BETTER, BUT THIS IS MY INTERPRETATION OF "THE STAR-SPANGLED BANNER" JUST FOR YOU.

THANK YOU.

NARRATOR: ONCE MODERN HUMANS HAD OPENED A ROUTE THROUGH THE DANUBE CORRIDOR, THE POPULATION KEPT GROWING.

AFRICA WAS LIKE A PUMP PUSHING MORE PEOPLE INTO EUROPE.

THE CENTRAL ZONE BETWEEN THE ICE SHEETS AND MOUNTAINS WAS PRIME REAL ESTATE.

IT BECAME ONE OF THE MOST DENSELY POPULATED PARTS OF THE PREHISTORIC WORLD-- A HUB OF SOCIAL CONNECTIONS.

ART WAS KEY TO THIS EXPANSION-- ALLOWING PEOPLE TO SHARE A CULTURE OF BELIEFS, TO FORGE THEIR OWN IDENTITY, AND MARK THEMSELVES OUT AS DIFFERENT.

BY CONTRAST, THERE IS NO EVIDENCE FROM SWABIA THAT NEANDERTHALS MADE ANY COMPLEX ART OR MUSIC.

IS THAT BECAUSE THEY WEREN'T CAPABLE OF SUCH THINGS, OR DIDN'T NEED THEM?

THERE WERE FEWER NEANDERTHALS LIVING IN SMALLER GROUPS THAT WERE LESS MOBILE.

THEY NEVER FORMED THE SOCIAL NETWORKS SO KEY TO MODERN HUMANS IN EUROPE.

CONARD: THE NUMBER OF PEOPLE A NEANDERTHAL INTERACTED WITH OVER THE COURSE OF HIS OR HER LIFE WOULD BE PERHAPS DOZENS OR SCORES OF PEOPLE.

MODERN HUMANS, IT COULD PERHAPS BE MANY HUNDREDS OF PEOPLE.

MODERN HUMANS HAD AN ENORMOUS WEALTH OF OBJECTS-- FIGURATIVE OBJECTS, MUSICAL INSTRUMENTS, ORNAMENTS THAT THEY NEEDED TO IDENTIFY EACH OTHER, TO COMMUNICATE WITH EACH OTHER.

NEANDERTHALS DIDN'T NEED THAT, AND WHEN THEY ENCOUNTERED IT, IT WAS UNFAMILIAR TO THEM, AND THEY STRUGGLED WITH IT.

NARRATOR: SINCE NEANDERTHALS WERE DISCOVERED OVER 150 YEARS AGO, SCIENTISTS HAVE BEEN TRYING TO WORK OUT WHAT HAPPENED TO THEM.

WHY DID THEY DISAPPEAR?

WE USED TO THINK THEY WERE OUTSMARTED BY MODERN HUMANS, BUT IT'S POSSIBLE THEY WERE SIMPLY OUTNUMBERED.

[PEOPLE SHOUTING INDISTINCTLY] THERE WOULD HAVE BEEN NO GREAT MOMENT OF EXTINCTION.

INSTEAD, THEY WOULD HAVE BEEN GRADUALLY ASSIMILATED BY US-- MODERN HUMANS.

HARVATI: NEANDERTHAL POPULATIONS SEEMED TO BE EXTREMELY SMALL-- A FEW THOUSAND PEOPLE ON A CONTINENTAL LEVEL.

MODERN HUMANS, FOR SOME REASON, WERE ABLE TO REPRODUCE FASTER AND MORE SUCCESSFULLY THAN NEANDERTHALS, PERHAPS ALSO RELYING ON-- ON CULTURE MORE.

UH, BUT THIS WOULD HAVE MADE, IN FACT, ALL THE DIFFERENCE.

NEANDERTHALS DIDN'T REALLY HAVE A CHANCE IN THE END.

[THUNDER] NARRATOR: WHEN NEANDERTHALS CEASED TO EXIST AS A SEPARATE SPECIES, TWO PEOPLES BECAME ONE, BUT NEANDERTHAL GENES LIVE ON IN OUR DNA.

HAWKS: ONCE WE LIVED IN A WORLD INHABITED BY ALL KINDS OF HUMANS-- NEANDERTHALS, DENISOVANS, PROBABLY SEVERAL DIFFERENT KINDS IN AFRICA.

AND NOW THEY'RE ALL GONE, AND WE'RE THE ONLY ONES THAT ARE LEFT.

WE WON THE GAME.

WE WERE BETTER AT CONNECTING, BETTER AT CREATING NETWORKS, BETTER AT LIVING IN LARGER GROUPS, AND THOSE THINGS ALL FEED ON EACH OTHER.

ONCE YOU'RE LIVING IN LARGER GROUPS, YOU'RE MAKING MORE CONNECTIONS.

YOU HAVE TO BECOME MORE CREATIVE.

IT'S AN EXPONENTIAL PROCESS.

WHERE WE END UP IS--IS HERE IN OUR MODERN, COMPLEX WORLD.

THIS IS THE END RESULT OF THOSE SEEDS SOWN BY THE FIRST PEOPLES AS THEY LEFT AFRICA AND COLONIZED EVERY CONTINENT OF THE WORLD.

NARRATOR: HOMO SAPIENS-- NOW THE ONLY HUMAN SPECIES ON THE PLANET.

WE MAY NOT HAVE BEEN SO MUCH SMARTER THAN OTHER HUMANS, BUT WE WERE MORE PLENTIFUL, MORE SOCIAL, MORE CULTURED.

WE ABSORBED THEIR GENES AND SHAPED OUR WORLD.

7 BILLION OF US TODAY ARE LIVING PROOF.

WE ARE ALL CHILDREN OF THE FIRST PEOPLES.

"FIRST PEOPLES" IS AVAILABLE ON DVD.

TO ORDER, VISIT SHOPPBS.ORG OR CALL 1-800-PLAY-PBS.