Ancient Unexplained Files (2021–…): Season 1, Episode 6 - Gladiator Graveyard - full transcript
Experts reveal the mystery behind a macabre scene of ancient execution.
[narrator] digital archeology
Reveals the true origins of machu picchu.
It's like trying to build manhattan
In the middle of the rockies.
It just doesn't make any sense.
[narrator] molecular science
Resolves a neolithic apocalypse.
It's one of the most significant
sites in human history.
What happened to this settlement
that was wiped out in a heartbeat?
[narrator] high-tech lasers
Trace the owners of a
stash worth millions of dollars.
This is real-life buried treasure.
It's as if they had found
the tomb of tutankhamun
On their island. I
mean, it's that big a deal.
[narrator] in a digital-technology
lab of the future,
Experts uncover clues
invisible to the naked eye.
I've never seen anything like that before.
[narrator] and solve mysteries
That have baffled for centuries.
That, right there, is what
scientists have been missing.
All the evidence points
to an incredible discovery.
This could be a game changer.
[narrator] state-of-the-art
digital technology,
Closes the toughest cases.
This mystery finally makes sense.
[narrator] from the
ancient unexplained files.
[narrator] york, England.
2004, a shallow mass
grave of mutilated bodies
Is unearthed beneath
a residential backyard.
They find a few bones
representing an individual.
And then more and more.
In total, they find 82 individuals.
[yeomans] this is a very grisly discovery.
It's clear that these individuals
Were subjected to
some terrible experiences.
Nearly three-quarters
of them were decapitated.
And many of the rest
had their skulls crushed.
[narrator] in the midst
of this bone wreckage
Is a skeletal wound, oddly out of place.
One of these skeletons
has a series of depressions
In the pelvic bones, right above the hips.
These injuries weren't
caused by any weapon.
It looks like the bite mark
of something big and scary.
It's baffling.
[narrator] now, can
cutting-edge digital analysis,
Solve the cause of this puncture wound,
Along with the rest of this
macabre human bone yard?
[auerbach] it's a grisly scene.
But the bones are a
treasure trove of clues.
Who are the victims of this grave?
[narrator] york archaeological
trust excavations
Take over a year.
The evidence of violence is astonishing.
Right out of the ground,
it's clear these skeletons
Have suffered some horrific neck injuries.
But they're very clean
injuries to the spinal column.
They're very likely to have
been made by a sword or an axe.
Many of the skulls have been cracked open.
And show evidence of
being hit with a hammer
Or perhaps the blunt end of a blade.
[narrator] to determine
when this butchery took place,
Bone fragments are sent for analysis.
Radiocarbon dating tells
us these bones are very old.
This isn't a modern day crime scene.
Nor is it a medieval one.
The bones are 1800 years old.
And they date back to roman times.
[narrator] in 71 ce,
The romans establish
york and name it eboracum.
This vital provincial
capital and military base
Supports the empire's
push north towards scotland.
York started off life
as a leisurely fortress.
And then becomes one of the leading cities
In roman britain.
And the largest city in northern britain,
And controlling a vast area of territory.
And would've been a very
flourishing, important place.
[narrator] by 306 ce,
The city's strategic value
led to constantine the great,
Being acclaimed resident emperor.
It had lively markets,
Baths, theaters, temples.
It was a very characteristic
roman city for 300 years.
[narrator] to maintain an iron
grip over their new territory
The romans utilized capital punishment.
High crimes are dealt
increasingly gory executions.
So, is it possible that
we're looking at a site
Of a mass execution of criminals?
It's well documented that
romans' methods of punishment
Were often quite brutal.
[auerbach] those sentenced
to die could be killed
In any number of ways.
They could be drowned.
They could be buried alive.
They could be cast from a great height.
They could be cast to
beasts to be devoured.
They could be crucified.
Or they could be decapitated.
It's possible this is a
roman execution cemetery.
And these bodies were beheaded.
Maybe that was the method of death.
[narrator] but when investigators
study the bodies anatomically,
A potential flaw arises.
[maca] if this were an execution cemetery,
You would expect to see there represented
A broad cross-section of society.
But this clearly isn't the case.
Analysis of the 82 individuals
Shows that all of them
were under the age of 45
And the vast majority were males.
[narrator] more curious,
They appear to be an elite force.
They're a bit larger than
the normal population.
So, these relatively well fed individuals.
Those who've gained a greater stature.
[valentine] the muscle attachments tell
us that these were big, muscular men.
But they were only really
developed on one side.
And this is consistent with
Very heavy weapons
training from a young age.
It's possible we could be looking
At a grave of roman soldiers.
[narrator] york is home to two legions.
The largest military
unit of the roman army.
One of the legendary vi legion victrix,
Who helped save cleopatra
in the siege of alexandria.
In this period, the romans
are constantly looking
To expand their territory.
And they were pushing the boundaries
Of the northern empire Well into scotland.
And, so, this puts the roman
armies on a collision course
With the fierce caledonian tribes.
[narrator] it's reckoned
around 50,000 roman soldiers
Are casualties of the
brutal war in the north.
[yeomans] so we would expect
To find the graves or the
remains of roman soldiers
Who were killed in
these very intense battles.
It's possible that this
grave could represent
Their final resting place.
[narrator] but, as experts
sift through bone injuries,
A strange set of puncture
wounds in a pelvis
Gives them pause for thought.
They're unlike anything
found from the battle field.
The pelvis is converted
into a virtual model.
The digital forensics lab
Allows bio medic greg szulgit,
Access to cutting-edge tech-analysis.
[szulgit] okay, we can clearly see that
This appears to be a bite mark
From some kind of large vicious creature.
The giveaway is that these indentations
Mirror a row of incisors.
The fact that these have penetrated
Both flesh and solid bone
Indicates tremendous force
That only a powerful animal is capable of.
Now, this presents a bigger mystery.
What is this formidable beast?
Nothing in britain matches this profile.
Hmm, okay, what else can
we learn from the pelvis?
Well, there are a few
circular wounds up here.
And it looks like, maybe,
A set of canine teeth
May have clamped on to the hip.
If I measure the diameter,
it's about a quarter-inch.
If this large hole is from a canine tooth,
Then this is from an apex predator.
Something like a big cat.
Let's call up a standard lion's jaw.
What's great about digital tech
Is that we can have it
chomp on this pelvis.
Look at this!
The incisors line up.
And the canines fit almost perfectly.
But here's the rub.
Lions went extinct in britain
More than 12,000 years ago.
Millennia before this guy was born.
It makes no sense at all.
[narrator] a roman cemetery,
Found in historic york, England,
Has thrown experts into confusion.
Among a litany of
gruesome skeletal injuries
Is a bite mark,
Likely by a big cat predator.
But lions went extinct in britain
more than 12,000 years ago.
[narrator] investigators now
hope this skeletons' backgrounds
May shed some more light.
They test tooth sample
for chemical elements
Called isotopes.
[horton] the simplest is diet.
We are what we eat.
And it's possible to look at two different
Isotopic pathways of carbon
Which are known as c3 and c4.
If we live on a diet of wheat and barley
And so forth, we're predominantly c3.
But if we are eating
middle-eastern crops, for example,
We'll have more of a stronger c4 signature.
And a number of these
individuals seem to have
C4 diets.
Which suggests that they'd come from
North africa area.
What we have is a group of strong,
Capable fighting men,
Drawn from the four corners of the empire.
All are buried in the same place.
They all show signs of injury by weapons
Across the entire course of their lives.
And one of them
Appears to have been savagely injured
By a large carnivore.
Taken all together,
This evidence leads to only one conclusion.
These men were not soldiers.
They were gladiators.
[victorious scream]
[narrator] gladiators are
lauded across the roman empire
And hollywood blockbusters.
Men would engage in
deadly hand to hand combat
Or as bestiary Against apex predators.
[horton] you've got two groups of bestiary.
One group who are
essentially the criminals.
And they're just placed
into the arena naked.
With nothing.
And the crowd watched
them being pulled to death.
[lion roars]
And then, you've then got the professionals
Who do this as a job
with their given weapons.
And they undertake these conflicts.
[narrator] most feared are the big cats.
An account tells of 200 roman bestiary
Being mauled by a single lion.
[yeomans] some sources indicate
That gladiators who were
forced to fight as bestiary
Would often prefer suicide.
Because they knew that
it would be, very likely,
A painful and violent end.
It's possible that some of
the people in the cemetery
Were criminals involved
in these spectacles.
But what's interesting is that
They're all being buried
in the revered fashion,
In proper cemeteries
And the decapitation
is part of a burial ritual.
So, it does suggest that these were mostly
Professional combatants
Paid to perform in the
circuses in ancient york.
[narrator] digital tech and science
Have pieced together
these freelance warriors
Buried in a backyard.
But one crucial mystery
Still eludes experts to this day.
[horton] what intrigues
me as an archeologist
Is where is the amphitheater
where this happened?
Because, so far, we
haven't found it in york.
[narrator] abu hureyra, syria.
In 1972,
Archeologists uncovered the
scorched remnants of an ancient village.
It's a huge mound that once contained
Series of circular dwellings.
Experts suspect that it
dates back to the stone age.
But extensive deposits of charred remains
Show that there was a big
catastrophe there at some point.
[narrator] mysteriously, the
burn patterns seem way off
Any normal phenomenon.
[szulgit] evidence of some charred remains
Suggests extremely high temperatures,
Far higher than any inferno would achieve.
This is mind-blowing.
[narrator] now, a new
scientific investigation
Aims to crack this half-century puzzle.
Revealing an earth-shattering event,
[loud explosion]
That turned the course of civilization.
Archeologists rate abu hureyra
As one of the most significant sites
In human history.
These hunter-gatherers
were a resourceful bunch.
Adept at not only surviving, but thriving.
What happened to this
once prosperous settlement
That was wiped out in a heartbeat?
[explosion]
[narrator] the incinerated
site is about 75 miles
From the city of aleppo.
In the 1970s, dictator hafez al-assad
Rubber stamps a large dam
That will flood the euphrates valley
And sink abu hureyra.
[wright] with the prospect that
abu hureyra will be lost forever,
Archeologists rushed to excavate the site
And salvaged materials.
[szulgit] during the excavations,
Sediment is taken away in
layers from excavation trenches.
Scientists discovered large
quantities of charcoal deposits
In one of the bottom layers.
They radiocarbon date the charcoal
To find that it's 12,800 years old.
[narrator] back then, this
region was starkly different
From today's arid wasteland.
Stone age humans
feasted on a bountiful land.
Civilization is said to have
developed independently
At six different sites across the globe.
Two of these are in the middle east,
In a region known as the fertile crescent.
And at its heart sits
the site of abu hureyra.
This would have been an ideal location
For a band of
hunter-gatherers at this time.
The nearby euphrates river
would've provided fresh fish.
And plenty of gazelles in migration
Offering a constant supply of fresh meat.
[narrator] but the fundamental
question of what obliterated abu hureyra
Stumps '70s investigators.
Fifty years later,
A new team takes up the challenge
And makes a striking discovery.
To put it in context,
Those temperatures would
turn something like your car
Into a molten pool of
metal in under a minute.
[narrator] in syria, A 1970s investigation
Into why stone age abu
hureyra was wiped off the map
Has hit a brick wall.
Scorched remnants defy normal explanation.
Now, a new team is on the hunt for answers.
It's hoped that by studying
the sediment layers once more,
We'll get some clues as
to what may have caused
Abu hureyra's sudden demise.
[proctor] in a sample of the charcoal,
Scientists find miniature
fragments of melt glass.
Melt glass forms from
incredibly high temperatures.
Far higher than any
house fire could achieve.
This categorically rules
out fire from being the culprit.
[narrator] scientists analyze
the melt glass composition
At an elemental level.
Using an energy-dispersive
x-ray spectroscopy test.
[proctor] this cutting-edge
technique allows scientists
To hit a sample with an electron beam
And measure the x-rays emitted.
This process reveals the
elements present in the sample.
[szulgit] the results show that the melt
glass contains quartz, zircon and chromite,
All of which have extremely
high melting temperatures.
[narrator] to determine
exactly what the temperature is,
Technicians fire up the lab furnaces
To fry the samples.
It's only when the lab furnaces max out
At 3,400 degrees fahrenheit,
That the scientists see
similar melt glass being made
As is found in the site at abu hureyra.
To put it in context,
Those temperatures would
turn something like your car
Into a molten pool of
metal in under a minute.
[narrator] by comparison,
Volcanic lava only reaches 2,200 degrees.
To generate the extraordinary
heat needed to create this melt glass,
An explosion of nuclear force is required.
Back in the stone age, one of the
few possible sources of that energy
Is a comet, meteor or asteroid.
[explosion]
[narrator] in 2017, researchers
find an asteroid strike in canada
Generated record temperatures
of over 4,300 degrees
Producing melt glass like abu hureyra.
But one potential flaw remains.
Surveys of abu hureyra
show no sign of a crater.
So one possible explanation
Is a comet or meteor
exploding in our atmosphere,
Otherwise known as an airburst.
[loud explosion]
When a comet enters the
earth's upper atmosphere
The rise and pressure in temperature
Can cause it to break up into pieces.
Each piece can generate a fireball
with almost a megaton of energy.
[loud explosion]
[narrator] scientists switched their focus
To finding irrefutable airburst evidence.
One telltale signature Is nanodiamonds.
Nanodiamonds are formed
under immense heat and pressure
From a cosmic impact.
They are ridiculously small.
You could fit more than 20 of them
On a single covid-19 viron.
So, finding them is like
a needle in a haystack.
[narrator] a tiny sediment
sample is doused in five acids.
Only nanodiamonds can
withstand this corrosive cocktail.
Essentially, this method
burns down the haystack
To find the needle.
[narrator] then a high-powered
electron microscope
Confirms their presence.
Proving, around 11,000 bce
Abu hureyra was instantly incinerated
By an airburst.
[explosion]
Evidence shows that these hunter-gatherers
Were really doing very well
with their chosen environment.
Microwear indicates stone tools
Were used to butcher
animals and to skin their hides.
Until, all of a sudden, these
hunter-gatherers would've seen
Just a gigantic flash and then
They would've been vaporized
along with everything around them.
[narrator] abu hureyra fell victim to
a devastating paleolithic catastrophe,
Known as the younger dryas impact.
Huge pieces of a two-mile wide comet
Blaze destruction from the
middle east to the americas.
The range of the younger
dryas boundary impact
Is mind-boggling.
Wildfires might have incinerated up to
Ten percent of all the
forested areas on the planet.
The impact sends dust and
ash high into the atmosphere
And the climate becomes colder and drier,
Particularly-in the northern hemisphere.
[narrator] incredibly,
some abu hureyra people
Survive the apocalypse.
But climate change
turns their garden of eden
Into dry scrubland.
Their extraordinary ability to adapt
Would have far-reaching implications.
Astonishingly, barley
and rye remains are found
Above the layer of destruction.
We also find stone tools
That were being used
to grind cereal grains.
This evidence suggests that
the inhabitants of abu hureyra
Began the first methods of farming
To replace the plants that they
couldn't find out in the wild anymore.
What we see is one of the
most profound alterations
In the course of human history.
This move to systematic farming
Was a huge leap forward in the
way we organized our societies
In the ancient past.
It is the building blocks
for complex civilizations
Such as we know today.
[narrator] the andes mountains, peru.
Almost 8,000 feet above sea-level,
Sits one of the new
seven wonders of the world.
The legendary machu picchu.
Machu picchu is in the middle
of a tropical mountain forest.
It's the most amazing urban
creation of the inca empire.
[koons] it is truly one of the most
astonishing man-made marvels.
The inca had a deep
appreciation of this landscape.
And they designed machu picchu in harmony.
[narrator] for over a century,
Experts have scrutinized the ruins.
But one key question still eludes them.
Why the inca civilization
chose this precarious site
For their sacred citadel.
The terrain is unbelievably jagged.
And there are sheer drops
to the river valley below.
The logistics of building
here are mind-boggling.
It's like trying to build manhattan
In the middle of the rockies.
It just doesn't make any sense.
[narrator] now, digital geoarchaeology
May finally unlock the hidden secret
To this architectural wonder.
We can see the machu
picchu stands right there.
It's uncanny.
X really does mark the spot.
[narrator] machu picchu,
The jewel of the inca empire.
Set over 80,000 acres,
Are more than 200 awe-inspiring buildings
Among dramatic plazas and terraces.
But one mystery continues
to confound experts.
Why build it high
In the inhospitable andes?
Machu picchu was
constructed in the mid-1400s.
This is the time of the
incan ruler pachacuti.
Why pachacuti chose this remote location
Defies logic.
There must be something
exceptional about this site
That made the incas move heaven and earth
To build here.
[narrator] most puzzling,
Is this environment
conspires against construction.
Not only was machu picchu
perched on this mountain top,
It's in an area plagued by earthquakes.
Surely, this is not the
best place to build a city.
[narrator] and altitude adds yet
another baffling layer to the mystery.
The rock here is 250
million-year-old granite.
It's hard. It's heavy. And
it's really difficult to mine.
[rose] transporting thousands
of these granite blocks
Up from the valley floor
or quarrying them up high
Seems unbelievable.
[narrator] now it's hoped, geoarchaeology
Applying earth science to historic sites,
Can crack this machu picchu conundrum.
Geological survey data is
used to create a 3d model.
This is loaded into the tech lab,
Ready for historian
sascha auerbach to analyze.
We created this detailed digital model
Of the machu picchu area.
Here we have the citadel.
And on either side, we've got the peaks,
Here and here.
So, the andes are renowned
for their tectonic activity.
It's crisscrossed with fault lines
And volcanos belch everywhere.
So, first, let us plot
some of those fault lines.
Here we can see three of those fault lines.
Machu picchu is built along
this one, marked in yellow.
And it's flanked by two
others, these white lines,
That are roughly parallel.
Now, between these two,
A chunk of land called
a graben has collapsed.
And this has had an interesting effect.
It's formed a dip between these two peaks.
More interestingly,
its created flatter land
On which you can build the citadel.
Geologists have plotted
the major andes fault lines
On a grand scale.
And this reveals something else.
If I zoom in,
We can see that machu
picchu stand right there
At the intersection of three
of these major fault lines.
It's uncanny. X really does mark the spot.
I think what we're seeing is a
crucial piece of a jigsaw puzzle
To explain why the incas built machu picchu
Right here.
[narrator] this positioning
seems beyond coincidence.
Further investigation reveals
the inca were savvy enough
To embrace this volatile
tectonic crossroads.
[proctor] the incas had a deep
appreciation of the landscape.
Where multiple fault lines meet,
the stones are more shattered,
Forming irregular shapes like triangles
and hexagons and rhombohedrals.
These are the exact same stones
The inca masons are
using to build machu picchu.
It's amazing that the
inca were handed these
Naturally quarried stone blocks on a plate.
The rocks naturally fracture
along planes of weakness.
It's easy to quarry following these lines.
And the granite has a
high crystalline structure
Which makes it very useful
For high tolerance carving.
[narrator] this enables the
inca to intricately assemble
Impressive structures,
Some using blocks weighing over 50 tons.
The walls of the citadel
are an absolute work of art.
The rocks fit together with such precision
That you can't even fit a
credit card between them.
And the inca, they didn't even use mortar.
[schwartz] the inca built the stones
To intricately interlock.
There's actually one stone
That has 30 precise angles to it.
[narrator] this masterful
dry stone construction
Is at the core of machu
picchu's astonishing longevity.
[proctor] they built the
walls with thick bases
To add sturdiness.
And there's no spaces within the cracks.
So, when the tremors hit,
The rocks kinda dance in position
And then settle back in place.
It's a master build,
Making this place earthquake proof.
[narrator] and setting up a
citadel in an earthquake hot zone
Confers one final crucial benefit.
This jungly area
Suffers torrential
rainstorms and flash flooding.
But the system of faults
Prevents machu picchu from
being washed off the mountain.
These deep cracks in the rocks
Efficiently drain excess water away.
Overall, the fault lines in machu picchu
Prove to be a blessing and not a curse.
[narrator] machu picchu is
considered the incas greatest legacy.
Now, earth science shows
how their innate ingenuity
Can harness nature.
The inca demonstrate an
incredible harmony with the land.
Choosing this inhospitable location
And turning it into this
mountain top paradise.
It is reckoned to be the
most amazing creation
Of the inca empire at its height.
[narrator] jersey, the british isles.
2012.
Metal detectorists on the island
Strike upon the find of a lifetime.
Buried just three feet below the surface,
Is a huge pile of green coins,
That are all fused together.
This is a stunning find.
The size of this hoard
is truly extraordinary.
No one has ever found
anything on this scale before.
[bellinger] this is real
life buried treasure.
For jersey, it's as if they had found
The tomb of tutankhamun on their island.
I mean, it's that big a deal.
[narrator] this is the largest
iron age coin haul found on earth
Worth millions of dollars today.
When deposited, it was a king's ransom.
Yet, unbelievably, it was left abandoned.
This is an incredibly valuable hoard.
So, who are the owners
And why didn't they come back for it?
There must be a crazy story here.
If we can work it out.
[narrator] archeologists
are hunting for the owners
Of huge stash of iron age coins
Found on the english
channel island, jersey.
Amazingly, this
once-in-a-lifetime discovery
Was 30 years in the making.
Starting with a young girl.
[rose] people say a farmer's daughter
Was given some ancient
coins dug up by her father.
Not knowing what they were,
she swapped them for comic books.
Locals have always wondered
If these coins were part of a buried hoard
Hidden somewhere on this island.
[narrator] this rumor inspired
two amateur metal detectorists.
After decades scouring farmers' fields,
In 2012, they hit pay dirt.
The coins were found in this lump.
And the whole thing was so compacted
That they couldn't
take it apart in the field.
Um, so, the approach was
to block-lift the whole lot,
Um, and take it to a laboratory.
[narrator] the mud-caked coin block
Weighs over a ton.
Being underground for centuries
Complicates identifying the mystery owner.
Copper corrodes when it's exposed to oxygen
Or water molecules in the ground.
This process fuses the old coins together
And creates a green film covering
the intricate designs on the coins.
[narrator] it takes almost three
years to unpick nearly 70,000 coins.
Each one's location is
recorded by laser probe.
While a laser scanner captures
individual surface details.
This laser is so precise
That it picks out intricate
details on each of the coins.
Such as a horse And the head of a man,
Which is crucial information.
The surface images and the
metallic make-up are like an id card,
Telling us that most coins
are from a powerful celtic tribe
Called the curiosolitae.
[narrator] metallurgical analysis
identifies the coins are made of billon,
An alloy of copper and silver
Consistent with coriosolite minting.
[horton] so the coriosolite are
the tribe living in northern France.
We also know from caesar's gaelic wars,
Um, that they were a bit of a
thorn in the side of the romans.
And the roman campaigns against them
Between 58 and 53 bc
Is well documented by caesar.
[men yelling]
But also well known, in terms of hill forts
That are located along the
northern french coastline.
[narrator] science and
old-fashioned detective work,
Have traced the owners of this
unprecedented iron age coin haul.
But one baffling mystery persists.
This collection of coins would've been
extremely valuable to the curiosolitae.
What would force this tribe to
make this dangerous passage
With this precious cargo
to bury it on the island
And never come back?
[narrator] more perplexing,
The coriosolite also relinquished
revered iron age symbols
Of wealth, power and connections.
[bellinger] within the coin pile
Are precious golden hoop neck-rings
Known as torcs.
Torcs were reserved for the
highest level of celtic society.
And elites would wear
them in important rituals.
They would even wear them into battles,
Such that it became associated,
Uh, inevitably, with the warrior class.
[horton] torcs are
highly prestigious items.
So, this kind of raises the
question of "what's going on?"
[narrator] it's a question that
continues to confound experts worldwide.
No one can agree why the coriosolite
Would inexplicably abandon
their treasure to the earth.
And other iron age coin
discoveries on jersey
Muddy the waters further.
The conventional
interpretation is essentially that
Taking the tribal treasure and
putting it on jersey for safe-keeping
Out of the reach of caesar's armies.
The other explanation,
Is that evidence of metallurgy
and craft activity on the site
Suggest the wealth of
the tribe is being brought,
Um, to be reworked, To be reminted.
But why did they never actually
recover the hoard afterwards?
The whole thing remains a bit of a mystery.
There are a number of
possibilities, to be honest.
All we can hope is that future research
Will help us uncover the truth, eventually.
[narrator] teposcolula-yucundaa, mexico.
2004.
Archeologists investigating
an historic mixtec settlement
Make a series of puzzling finds.
The most striking thing
about teposcolula-yucundaa,
Is that the mixtec have
dropped everything to leave town.
[narrator] chilling evidence
of what caused them to flee
Is found in the town's central plaza.
They find these oval-shaped holes
That have been cut into
this really ornate plaster floor.
And inside are human remains.
It was as if they would open a hole
And stuff it with as
many bodies as possible.
What is particularly mysterious
is that this type of burial
Doesn't follow any of the
traditional mixtec forms.
[narrator] records reveal
teposcolula-yucundaa
Was abandoned in the mid-16th century,
Right at the time an unknown plague
Is ripping through mesoamerica.
The locals and the spanish had never seen
A disease like this.
It was the ultimate,
sort of, mystery killer.
This endemic is estimated to have wiped out
Up to 80% of the central
american population.
That's even more than the black death
That ravaged the european
populations in the middle ages.
[narrator] over the centuries,
No one has been able to pin down the cause
Of this killer plague.
Now, it's hoped the latest
in digital genome analysis
Can finally unlock its secrets.
The cemetery may hold the bodies
From one of the worst
epidemics in human history.
[king] the question is,
what is this lethal killer?
And how is it spreading like wildfire,
Killing the local population?
[narrator] the abandoned mixtec
town, teposcolula-yucundaa,
Is rumored to be ground-zero
For a mystery 16th century plague.
The finger of blame
pointed to spanish invaders.
They arrive in mesoamerica in 1519
On a brutal pillage for gold.
The native population had zero chance
Against these conquistadors.
Not only because of
their weapons, their guns,
But also because of their germs.
The immune systems of the
natives just couldn't withstand them.
This led to one of the most
horrific one-sided assaults
Of a people ever seen in history.
[narrator] smallpox,
measles, influenza and malaria
Decimate native mesoamericans.
But one invisible killer
defies explanation.
The locals referred to it as cocoliztli,
Great pestilence.
It was a disease that resulted
In severe abdominal pains, fevers,
And bleeding from the eyes and the mouth.
Death usually resulted in a few days.
One spanish priest
States that he buried over
10,000 people in a single year.
To put that in perspective,
There were scores of
spanish priests in that area.
[king] was this something
that's been brought over
From europe with the spaniards?
Or is it some hitherto unknown,
Sort of, killer disease
from deep in the jungle?
[narrator] scientist believe that
teposcolula-yucundaa plague pits
May provide the vital missing link.
They start by scouring the
human remains for pathogens.
Using polymerase chain reaction or pcr.
Polymerase chain reaction is a technique
Which means we can use a tiny bit of dna
And it can be replicated
over and over again.
Billions of times.
And then it can be examined.
In this case, polymerase chain reaction
Can be used to examine an ancient pathogen,
Something that caused
this terrible disease.
[narrator] but the teams
best efforts are thwarted.
Millions of dna molecules
from sources like fungi,
Plants, insects and animals,
Severely cloud the results.
To combat this, focus is
switched to the victim's inner teeth.
Scientists reckon that the
best way of looking at the dna
Of a blood-borne pathogen,
is to look at the tooth pulp.
Because the tooth enamel will protect that
From external contaminants.
After looking at the dna samples,
There are several thousand
different bacterial species.
Finding the one that may have
been the killer is a daunting prospect.
To crack this case, they need
a large-scale screening process.
[narrator] this crucial
breakthrough comes in 2016
Via a new generation
of bio-informatics tech.
The megan alignment tool or malt.
So, what's really, really cool
Is that it has completely
revolutionized ancient dna research.
What scientists do is they take
All of the strands of dna
that have been sequenced
And use a computer program
To, basically, say, "right, where
is this dna sequence from?"
And match it against databases of known
Modern, uh, bacterial dna sequences.
Essentially, sifting through
all the information for you
To find tiny bits of evidence of pathogens
That were previously hidden to us.
[narrator] malt crunches the
data from these new samples,
Screening for any
hint of a killer pathogen.
The sequencing discounts
the usual suspects.
Smallpox, measles, flu.
But it does land on one suspect.
In a few teeth, they find pieces of dna
From salmonella enterica.
The cause for enteric fever.
[narrator] crucially, enteric fever
matches many of the symptoms
Described during the cocoliztli epidemic.
Until this discovery among these skeletons,
Nothing was actually
known about the prevalence
Of this particular pathogen
In the past and among these people.
Cutting-edge science has
now been able to identify
The bacteria that was
part of this huge epidemic
And decline in this population.
[narrator] but one mystery remains.
How did this deadly pathogen flare up
In 16th century mesoamerica?
Scientists run the same tests on burials
That pre-date european contact
And find no example of enteric fever.
The blame for this disease falls
squarely on spanish colonizers.
It's thought that the europeans
carried the bug to the americas
Through livestock or
through human carriers.
Once in the americas,
It would leech into the
food and water supplies
Through vomit and fecal
material of sick individuals.
It would then spread and ultimately kill
Millions of the central
american population.
[narrator] having cracked
this centuries-old case
At teposcolula-yucundaa,
Next generation genomic analysis
Is being touted as the pathogen pioneer,
A crucial bio-informatics tool
For unlocking our hidden
disease-ravaged past.
[king] many historic diseases
were absolutely catastrophic.
I mean, they collapsed cities.
Entire populations were decimated.
But now, with this cutting-edge science,
We can understand more about
how these deadly pathogens
Have shaped human history.
Reveals the true origins of machu picchu.
It's like trying to build manhattan
In the middle of the rockies.
It just doesn't make any sense.
[narrator] molecular science
Resolves a neolithic apocalypse.
It's one of the most significant
sites in human history.
What happened to this settlement
that was wiped out in a heartbeat?
[narrator] high-tech lasers
Trace the owners of a
stash worth millions of dollars.
This is real-life buried treasure.
It's as if they had found
the tomb of tutankhamun
On their island. I
mean, it's that big a deal.
[narrator] in a digital-technology
lab of the future,
Experts uncover clues
invisible to the naked eye.
I've never seen anything like that before.
[narrator] and solve mysteries
That have baffled for centuries.
That, right there, is what
scientists have been missing.
All the evidence points
to an incredible discovery.
This could be a game changer.
[narrator] state-of-the-art
digital technology,
Closes the toughest cases.
This mystery finally makes sense.
[narrator] from the
ancient unexplained files.
[narrator] york, England.
2004, a shallow mass
grave of mutilated bodies
Is unearthed beneath
a residential backyard.
They find a few bones
representing an individual.
And then more and more.
In total, they find 82 individuals.
[yeomans] this is a very grisly discovery.
It's clear that these individuals
Were subjected to
some terrible experiences.
Nearly three-quarters
of them were decapitated.
And many of the rest
had their skulls crushed.
[narrator] in the midst
of this bone wreckage
Is a skeletal wound, oddly out of place.
One of these skeletons
has a series of depressions
In the pelvic bones, right above the hips.
These injuries weren't
caused by any weapon.
It looks like the bite mark
of something big and scary.
It's baffling.
[narrator] now, can
cutting-edge digital analysis,
Solve the cause of this puncture wound,
Along with the rest of this
macabre human bone yard?
[auerbach] it's a grisly scene.
But the bones are a
treasure trove of clues.
Who are the victims of this grave?
[narrator] york archaeological
trust excavations
Take over a year.
The evidence of violence is astonishing.
Right out of the ground,
it's clear these skeletons
Have suffered some horrific neck injuries.
But they're very clean
injuries to the spinal column.
They're very likely to have
been made by a sword or an axe.
Many of the skulls have been cracked open.
And show evidence of
being hit with a hammer
Or perhaps the blunt end of a blade.
[narrator] to determine
when this butchery took place,
Bone fragments are sent for analysis.
Radiocarbon dating tells
us these bones are very old.
This isn't a modern day crime scene.
Nor is it a medieval one.
The bones are 1800 years old.
And they date back to roman times.
[narrator] in 71 ce,
The romans establish
york and name it eboracum.
This vital provincial
capital and military base
Supports the empire's
push north towards scotland.
York started off life
as a leisurely fortress.
And then becomes one of the leading cities
In roman britain.
And the largest city in northern britain,
And controlling a vast area of territory.
And would've been a very
flourishing, important place.
[narrator] by 306 ce,
The city's strategic value
led to constantine the great,
Being acclaimed resident emperor.
It had lively markets,
Baths, theaters, temples.
It was a very characteristic
roman city for 300 years.
[narrator] to maintain an iron
grip over their new territory
The romans utilized capital punishment.
High crimes are dealt
increasingly gory executions.
So, is it possible that
we're looking at a site
Of a mass execution of criminals?
It's well documented that
romans' methods of punishment
Were often quite brutal.
[auerbach] those sentenced
to die could be killed
In any number of ways.
They could be drowned.
They could be buried alive.
They could be cast from a great height.
They could be cast to
beasts to be devoured.
They could be crucified.
Or they could be decapitated.
It's possible this is a
roman execution cemetery.
And these bodies were beheaded.
Maybe that was the method of death.
[narrator] but when investigators
study the bodies anatomically,
A potential flaw arises.
[maca] if this were an execution cemetery,
You would expect to see there represented
A broad cross-section of society.
But this clearly isn't the case.
Analysis of the 82 individuals
Shows that all of them
were under the age of 45
And the vast majority were males.
[narrator] more curious,
They appear to be an elite force.
They're a bit larger than
the normal population.
So, these relatively well fed individuals.
Those who've gained a greater stature.
[valentine] the muscle attachments tell
us that these were big, muscular men.
But they were only really
developed on one side.
And this is consistent with
Very heavy weapons
training from a young age.
It's possible we could be looking
At a grave of roman soldiers.
[narrator] york is home to two legions.
The largest military
unit of the roman army.
One of the legendary vi legion victrix,
Who helped save cleopatra
in the siege of alexandria.
In this period, the romans
are constantly looking
To expand their territory.
And they were pushing the boundaries
Of the northern empire Well into scotland.
And, so, this puts the roman
armies on a collision course
With the fierce caledonian tribes.
[narrator] it's reckoned
around 50,000 roman soldiers
Are casualties of the
brutal war in the north.
[yeomans] so we would expect
To find the graves or the
remains of roman soldiers
Who were killed in
these very intense battles.
It's possible that this
grave could represent
Their final resting place.
[narrator] but, as experts
sift through bone injuries,
A strange set of puncture
wounds in a pelvis
Gives them pause for thought.
They're unlike anything
found from the battle field.
The pelvis is converted
into a virtual model.
The digital forensics lab
Allows bio medic greg szulgit,
Access to cutting-edge tech-analysis.
[szulgit] okay, we can clearly see that
This appears to be a bite mark
From some kind of large vicious creature.
The giveaway is that these indentations
Mirror a row of incisors.
The fact that these have penetrated
Both flesh and solid bone
Indicates tremendous force
That only a powerful animal is capable of.
Now, this presents a bigger mystery.
What is this formidable beast?
Nothing in britain matches this profile.
Hmm, okay, what else can
we learn from the pelvis?
Well, there are a few
circular wounds up here.
And it looks like, maybe,
A set of canine teeth
May have clamped on to the hip.
If I measure the diameter,
it's about a quarter-inch.
If this large hole is from a canine tooth,
Then this is from an apex predator.
Something like a big cat.
Let's call up a standard lion's jaw.
What's great about digital tech
Is that we can have it
chomp on this pelvis.
Look at this!
The incisors line up.
And the canines fit almost perfectly.
But here's the rub.
Lions went extinct in britain
More than 12,000 years ago.
Millennia before this guy was born.
It makes no sense at all.
[narrator] a roman cemetery,
Found in historic york, England,
Has thrown experts into confusion.
Among a litany of
gruesome skeletal injuries
Is a bite mark,
Likely by a big cat predator.
But lions went extinct in britain
more than 12,000 years ago.
[narrator] investigators now
hope this skeletons' backgrounds
May shed some more light.
They test tooth sample
for chemical elements
Called isotopes.
[horton] the simplest is diet.
We are what we eat.
And it's possible to look at two different
Isotopic pathways of carbon
Which are known as c3 and c4.
If we live on a diet of wheat and barley
And so forth, we're predominantly c3.
But if we are eating
middle-eastern crops, for example,
We'll have more of a stronger c4 signature.
And a number of these
individuals seem to have
C4 diets.
Which suggests that they'd come from
North africa area.
What we have is a group of strong,
Capable fighting men,
Drawn from the four corners of the empire.
All are buried in the same place.
They all show signs of injury by weapons
Across the entire course of their lives.
And one of them
Appears to have been savagely injured
By a large carnivore.
Taken all together,
This evidence leads to only one conclusion.
These men were not soldiers.
They were gladiators.
[victorious scream]
[narrator] gladiators are
lauded across the roman empire
And hollywood blockbusters.
Men would engage in
deadly hand to hand combat
Or as bestiary Against apex predators.
[horton] you've got two groups of bestiary.
One group who are
essentially the criminals.
And they're just placed
into the arena naked.
With nothing.
And the crowd watched
them being pulled to death.
[lion roars]
And then, you've then got the professionals
Who do this as a job
with their given weapons.
And they undertake these conflicts.
[narrator] most feared are the big cats.
An account tells of 200 roman bestiary
Being mauled by a single lion.
[yeomans] some sources indicate
That gladiators who were
forced to fight as bestiary
Would often prefer suicide.
Because they knew that
it would be, very likely,
A painful and violent end.
It's possible that some of
the people in the cemetery
Were criminals involved
in these spectacles.
But what's interesting is that
They're all being buried
in the revered fashion,
In proper cemeteries
And the decapitation
is part of a burial ritual.
So, it does suggest that these were mostly
Professional combatants
Paid to perform in the
circuses in ancient york.
[narrator] digital tech and science
Have pieced together
these freelance warriors
Buried in a backyard.
But one crucial mystery
Still eludes experts to this day.
[horton] what intrigues
me as an archeologist
Is where is the amphitheater
where this happened?
Because, so far, we
haven't found it in york.
[narrator] abu hureyra, syria.
In 1972,
Archeologists uncovered the
scorched remnants of an ancient village.
It's a huge mound that once contained
Series of circular dwellings.
Experts suspect that it
dates back to the stone age.
But extensive deposits of charred remains
Show that there was a big
catastrophe there at some point.
[narrator] mysteriously, the
burn patterns seem way off
Any normal phenomenon.
[szulgit] evidence of some charred remains
Suggests extremely high temperatures,
Far higher than any inferno would achieve.
This is mind-blowing.
[narrator] now, a new
scientific investigation
Aims to crack this half-century puzzle.
Revealing an earth-shattering event,
[loud explosion]
That turned the course of civilization.
Archeologists rate abu hureyra
As one of the most significant sites
In human history.
These hunter-gatherers
were a resourceful bunch.
Adept at not only surviving, but thriving.
What happened to this
once prosperous settlement
That was wiped out in a heartbeat?
[explosion]
[narrator] the incinerated
site is about 75 miles
From the city of aleppo.
In the 1970s, dictator hafez al-assad
Rubber stamps a large dam
That will flood the euphrates valley
And sink abu hureyra.
[wright] with the prospect that
abu hureyra will be lost forever,
Archeologists rushed to excavate the site
And salvaged materials.
[szulgit] during the excavations,
Sediment is taken away in
layers from excavation trenches.
Scientists discovered large
quantities of charcoal deposits
In one of the bottom layers.
They radiocarbon date the charcoal
To find that it's 12,800 years old.
[narrator] back then, this
region was starkly different
From today's arid wasteland.
Stone age humans
feasted on a bountiful land.
Civilization is said to have
developed independently
At six different sites across the globe.
Two of these are in the middle east,
In a region known as the fertile crescent.
And at its heart sits
the site of abu hureyra.
This would have been an ideal location
For a band of
hunter-gatherers at this time.
The nearby euphrates river
would've provided fresh fish.
And plenty of gazelles in migration
Offering a constant supply of fresh meat.
[narrator] but the fundamental
question of what obliterated abu hureyra
Stumps '70s investigators.
Fifty years later,
A new team takes up the challenge
And makes a striking discovery.
To put it in context,
Those temperatures would
turn something like your car
Into a molten pool of
metal in under a minute.
[narrator] in syria, A 1970s investigation
Into why stone age abu
hureyra was wiped off the map
Has hit a brick wall.
Scorched remnants defy normal explanation.
Now, a new team is on the hunt for answers.
It's hoped that by studying
the sediment layers once more,
We'll get some clues as
to what may have caused
Abu hureyra's sudden demise.
[proctor] in a sample of the charcoal,
Scientists find miniature
fragments of melt glass.
Melt glass forms from
incredibly high temperatures.
Far higher than any
house fire could achieve.
This categorically rules
out fire from being the culprit.
[narrator] scientists analyze
the melt glass composition
At an elemental level.
Using an energy-dispersive
x-ray spectroscopy test.
[proctor] this cutting-edge
technique allows scientists
To hit a sample with an electron beam
And measure the x-rays emitted.
This process reveals the
elements present in the sample.
[szulgit] the results show that the melt
glass contains quartz, zircon and chromite,
All of which have extremely
high melting temperatures.
[narrator] to determine
exactly what the temperature is,
Technicians fire up the lab furnaces
To fry the samples.
It's only when the lab furnaces max out
At 3,400 degrees fahrenheit,
That the scientists see
similar melt glass being made
As is found in the site at abu hureyra.
To put it in context,
Those temperatures would
turn something like your car
Into a molten pool of
metal in under a minute.
[narrator] by comparison,
Volcanic lava only reaches 2,200 degrees.
To generate the extraordinary
heat needed to create this melt glass,
An explosion of nuclear force is required.
Back in the stone age, one of the
few possible sources of that energy
Is a comet, meteor or asteroid.
[explosion]
[narrator] in 2017, researchers
find an asteroid strike in canada
Generated record temperatures
of over 4,300 degrees
Producing melt glass like abu hureyra.
But one potential flaw remains.
Surveys of abu hureyra
show no sign of a crater.
So one possible explanation
Is a comet or meteor
exploding in our atmosphere,
Otherwise known as an airburst.
[loud explosion]
When a comet enters the
earth's upper atmosphere
The rise and pressure in temperature
Can cause it to break up into pieces.
Each piece can generate a fireball
with almost a megaton of energy.
[loud explosion]
[narrator] scientists switched their focus
To finding irrefutable airburst evidence.
One telltale signature Is nanodiamonds.
Nanodiamonds are formed
under immense heat and pressure
From a cosmic impact.
They are ridiculously small.
You could fit more than 20 of them
On a single covid-19 viron.
So, finding them is like
a needle in a haystack.
[narrator] a tiny sediment
sample is doused in five acids.
Only nanodiamonds can
withstand this corrosive cocktail.
Essentially, this method
burns down the haystack
To find the needle.
[narrator] then a high-powered
electron microscope
Confirms their presence.
Proving, around 11,000 bce
Abu hureyra was instantly incinerated
By an airburst.
[explosion]
Evidence shows that these hunter-gatherers
Were really doing very well
with their chosen environment.
Microwear indicates stone tools
Were used to butcher
animals and to skin their hides.
Until, all of a sudden, these
hunter-gatherers would've seen
Just a gigantic flash and then
They would've been vaporized
along with everything around them.
[narrator] abu hureyra fell victim to
a devastating paleolithic catastrophe,
Known as the younger dryas impact.
Huge pieces of a two-mile wide comet
Blaze destruction from the
middle east to the americas.
The range of the younger
dryas boundary impact
Is mind-boggling.
Wildfires might have incinerated up to
Ten percent of all the
forested areas on the planet.
The impact sends dust and
ash high into the atmosphere
And the climate becomes colder and drier,
Particularly-in the northern hemisphere.
[narrator] incredibly,
some abu hureyra people
Survive the apocalypse.
But climate change
turns their garden of eden
Into dry scrubland.
Their extraordinary ability to adapt
Would have far-reaching implications.
Astonishingly, barley
and rye remains are found
Above the layer of destruction.
We also find stone tools
That were being used
to grind cereal grains.
This evidence suggests that
the inhabitants of abu hureyra
Began the first methods of farming
To replace the plants that they
couldn't find out in the wild anymore.
What we see is one of the
most profound alterations
In the course of human history.
This move to systematic farming
Was a huge leap forward in the
way we organized our societies
In the ancient past.
It is the building blocks
for complex civilizations
Such as we know today.
[narrator] the andes mountains, peru.
Almost 8,000 feet above sea-level,
Sits one of the new
seven wonders of the world.
The legendary machu picchu.
Machu picchu is in the middle
of a tropical mountain forest.
It's the most amazing urban
creation of the inca empire.
[koons] it is truly one of the most
astonishing man-made marvels.
The inca had a deep
appreciation of this landscape.
And they designed machu picchu in harmony.
[narrator] for over a century,
Experts have scrutinized the ruins.
But one key question still eludes them.
Why the inca civilization
chose this precarious site
For their sacred citadel.
The terrain is unbelievably jagged.
And there are sheer drops
to the river valley below.
The logistics of building
here are mind-boggling.
It's like trying to build manhattan
In the middle of the rockies.
It just doesn't make any sense.
[narrator] now, digital geoarchaeology
May finally unlock the hidden secret
To this architectural wonder.
We can see the machu
picchu stands right there.
It's uncanny.
X really does mark the spot.
[narrator] machu picchu,
The jewel of the inca empire.
Set over 80,000 acres,
Are more than 200 awe-inspiring buildings
Among dramatic plazas and terraces.
But one mystery continues
to confound experts.
Why build it high
In the inhospitable andes?
Machu picchu was
constructed in the mid-1400s.
This is the time of the
incan ruler pachacuti.
Why pachacuti chose this remote location
Defies logic.
There must be something
exceptional about this site
That made the incas move heaven and earth
To build here.
[narrator] most puzzling,
Is this environment
conspires against construction.
Not only was machu picchu
perched on this mountain top,
It's in an area plagued by earthquakes.
Surely, this is not the
best place to build a city.
[narrator] and altitude adds yet
another baffling layer to the mystery.
The rock here is 250
million-year-old granite.
It's hard. It's heavy. And
it's really difficult to mine.
[rose] transporting thousands
of these granite blocks
Up from the valley floor
or quarrying them up high
Seems unbelievable.
[narrator] now it's hoped, geoarchaeology
Applying earth science to historic sites,
Can crack this machu picchu conundrum.
Geological survey data is
used to create a 3d model.
This is loaded into the tech lab,
Ready for historian
sascha auerbach to analyze.
We created this detailed digital model
Of the machu picchu area.
Here we have the citadel.
And on either side, we've got the peaks,
Here and here.
So, the andes are renowned
for their tectonic activity.
It's crisscrossed with fault lines
And volcanos belch everywhere.
So, first, let us plot
some of those fault lines.
Here we can see three of those fault lines.
Machu picchu is built along
this one, marked in yellow.
And it's flanked by two
others, these white lines,
That are roughly parallel.
Now, between these two,
A chunk of land called
a graben has collapsed.
And this has had an interesting effect.
It's formed a dip between these two peaks.
More interestingly,
its created flatter land
On which you can build the citadel.
Geologists have plotted
the major andes fault lines
On a grand scale.
And this reveals something else.
If I zoom in,
We can see that machu
picchu stand right there
At the intersection of three
of these major fault lines.
It's uncanny. X really does mark the spot.
I think what we're seeing is a
crucial piece of a jigsaw puzzle
To explain why the incas built machu picchu
Right here.
[narrator] this positioning
seems beyond coincidence.
Further investigation reveals
the inca were savvy enough
To embrace this volatile
tectonic crossroads.
[proctor] the incas had a deep
appreciation of the landscape.
Where multiple fault lines meet,
the stones are more shattered,
Forming irregular shapes like triangles
and hexagons and rhombohedrals.
These are the exact same stones
The inca masons are
using to build machu picchu.
It's amazing that the
inca were handed these
Naturally quarried stone blocks on a plate.
The rocks naturally fracture
along planes of weakness.
It's easy to quarry following these lines.
And the granite has a
high crystalline structure
Which makes it very useful
For high tolerance carving.
[narrator] this enables the
inca to intricately assemble
Impressive structures,
Some using blocks weighing over 50 tons.
The walls of the citadel
are an absolute work of art.
The rocks fit together with such precision
That you can't even fit a
credit card between them.
And the inca, they didn't even use mortar.
[schwartz] the inca built the stones
To intricately interlock.
There's actually one stone
That has 30 precise angles to it.
[narrator] this masterful
dry stone construction
Is at the core of machu
picchu's astonishing longevity.
[proctor] they built the
walls with thick bases
To add sturdiness.
And there's no spaces within the cracks.
So, when the tremors hit,
The rocks kinda dance in position
And then settle back in place.
It's a master build,
Making this place earthquake proof.
[narrator] and setting up a
citadel in an earthquake hot zone
Confers one final crucial benefit.
This jungly area
Suffers torrential
rainstorms and flash flooding.
But the system of faults
Prevents machu picchu from
being washed off the mountain.
These deep cracks in the rocks
Efficiently drain excess water away.
Overall, the fault lines in machu picchu
Prove to be a blessing and not a curse.
[narrator] machu picchu is
considered the incas greatest legacy.
Now, earth science shows
how their innate ingenuity
Can harness nature.
The inca demonstrate an
incredible harmony with the land.
Choosing this inhospitable location
And turning it into this
mountain top paradise.
It is reckoned to be the
most amazing creation
Of the inca empire at its height.
[narrator] jersey, the british isles.
2012.
Metal detectorists on the island
Strike upon the find of a lifetime.
Buried just three feet below the surface,
Is a huge pile of green coins,
That are all fused together.
This is a stunning find.
The size of this hoard
is truly extraordinary.
No one has ever found
anything on this scale before.
[bellinger] this is real
life buried treasure.
For jersey, it's as if they had found
The tomb of tutankhamun on their island.
I mean, it's that big a deal.
[narrator] this is the largest
iron age coin haul found on earth
Worth millions of dollars today.
When deposited, it was a king's ransom.
Yet, unbelievably, it was left abandoned.
This is an incredibly valuable hoard.
So, who are the owners
And why didn't they come back for it?
There must be a crazy story here.
If we can work it out.
[narrator] archeologists
are hunting for the owners
Of huge stash of iron age coins
Found on the english
channel island, jersey.
Amazingly, this
once-in-a-lifetime discovery
Was 30 years in the making.
Starting with a young girl.
[rose] people say a farmer's daughter
Was given some ancient
coins dug up by her father.
Not knowing what they were,
she swapped them for comic books.
Locals have always wondered
If these coins were part of a buried hoard
Hidden somewhere on this island.
[narrator] this rumor inspired
two amateur metal detectorists.
After decades scouring farmers' fields,
In 2012, they hit pay dirt.
The coins were found in this lump.
And the whole thing was so compacted
That they couldn't
take it apart in the field.
Um, so, the approach was
to block-lift the whole lot,
Um, and take it to a laboratory.
[narrator] the mud-caked coin block
Weighs over a ton.
Being underground for centuries
Complicates identifying the mystery owner.
Copper corrodes when it's exposed to oxygen
Or water molecules in the ground.
This process fuses the old coins together
And creates a green film covering
the intricate designs on the coins.
[narrator] it takes almost three
years to unpick nearly 70,000 coins.
Each one's location is
recorded by laser probe.
While a laser scanner captures
individual surface details.
This laser is so precise
That it picks out intricate
details on each of the coins.
Such as a horse And the head of a man,
Which is crucial information.
The surface images and the
metallic make-up are like an id card,
Telling us that most coins
are from a powerful celtic tribe
Called the curiosolitae.
[narrator] metallurgical analysis
identifies the coins are made of billon,
An alloy of copper and silver
Consistent with coriosolite minting.
[horton] so the coriosolite are
the tribe living in northern France.
We also know from caesar's gaelic wars,
Um, that they were a bit of a
thorn in the side of the romans.
And the roman campaigns against them
Between 58 and 53 bc
Is well documented by caesar.
[men yelling]
But also well known, in terms of hill forts
That are located along the
northern french coastline.
[narrator] science and
old-fashioned detective work,
Have traced the owners of this
unprecedented iron age coin haul.
But one baffling mystery persists.
This collection of coins would've been
extremely valuable to the curiosolitae.
What would force this tribe to
make this dangerous passage
With this precious cargo
to bury it on the island
And never come back?
[narrator] more perplexing,
The coriosolite also relinquished
revered iron age symbols
Of wealth, power and connections.
[bellinger] within the coin pile
Are precious golden hoop neck-rings
Known as torcs.
Torcs were reserved for the
highest level of celtic society.
And elites would wear
them in important rituals.
They would even wear them into battles,
Such that it became associated,
Uh, inevitably, with the warrior class.
[horton] torcs are
highly prestigious items.
So, this kind of raises the
question of "what's going on?"
[narrator] it's a question that
continues to confound experts worldwide.
No one can agree why the coriosolite
Would inexplicably abandon
their treasure to the earth.
And other iron age coin
discoveries on jersey
Muddy the waters further.
The conventional
interpretation is essentially that
Taking the tribal treasure and
putting it on jersey for safe-keeping
Out of the reach of caesar's armies.
The other explanation,
Is that evidence of metallurgy
and craft activity on the site
Suggest the wealth of
the tribe is being brought,
Um, to be reworked, To be reminted.
But why did they never actually
recover the hoard afterwards?
The whole thing remains a bit of a mystery.
There are a number of
possibilities, to be honest.
All we can hope is that future research
Will help us uncover the truth, eventually.
[narrator] teposcolula-yucundaa, mexico.
2004.
Archeologists investigating
an historic mixtec settlement
Make a series of puzzling finds.
The most striking thing
about teposcolula-yucundaa,
Is that the mixtec have
dropped everything to leave town.
[narrator] chilling evidence
of what caused them to flee
Is found in the town's central plaza.
They find these oval-shaped holes
That have been cut into
this really ornate plaster floor.
And inside are human remains.
It was as if they would open a hole
And stuff it with as
many bodies as possible.
What is particularly mysterious
is that this type of burial
Doesn't follow any of the
traditional mixtec forms.
[narrator] records reveal
teposcolula-yucundaa
Was abandoned in the mid-16th century,
Right at the time an unknown plague
Is ripping through mesoamerica.
The locals and the spanish had never seen
A disease like this.
It was the ultimate,
sort of, mystery killer.
This endemic is estimated to have wiped out
Up to 80% of the central
american population.
That's even more than the black death
That ravaged the european
populations in the middle ages.
[narrator] over the centuries,
No one has been able to pin down the cause
Of this killer plague.
Now, it's hoped the latest
in digital genome analysis
Can finally unlock its secrets.
The cemetery may hold the bodies
From one of the worst
epidemics in human history.
[king] the question is,
what is this lethal killer?
And how is it spreading like wildfire,
Killing the local population?
[narrator] the abandoned mixtec
town, teposcolula-yucundaa,
Is rumored to be ground-zero
For a mystery 16th century plague.
The finger of blame
pointed to spanish invaders.
They arrive in mesoamerica in 1519
On a brutal pillage for gold.
The native population had zero chance
Against these conquistadors.
Not only because of
their weapons, their guns,
But also because of their germs.
The immune systems of the
natives just couldn't withstand them.
This led to one of the most
horrific one-sided assaults
Of a people ever seen in history.
[narrator] smallpox,
measles, influenza and malaria
Decimate native mesoamericans.
But one invisible killer
defies explanation.
The locals referred to it as cocoliztli,
Great pestilence.
It was a disease that resulted
In severe abdominal pains, fevers,
And bleeding from the eyes and the mouth.
Death usually resulted in a few days.
One spanish priest
States that he buried over
10,000 people in a single year.
To put that in perspective,
There were scores of
spanish priests in that area.
[king] was this something
that's been brought over
From europe with the spaniards?
Or is it some hitherto unknown,
Sort of, killer disease
from deep in the jungle?
[narrator] scientist believe that
teposcolula-yucundaa plague pits
May provide the vital missing link.
They start by scouring the
human remains for pathogens.
Using polymerase chain reaction or pcr.
Polymerase chain reaction is a technique
Which means we can use a tiny bit of dna
And it can be replicated
over and over again.
Billions of times.
And then it can be examined.
In this case, polymerase chain reaction
Can be used to examine an ancient pathogen,
Something that caused
this terrible disease.
[narrator] but the teams
best efforts are thwarted.
Millions of dna molecules
from sources like fungi,
Plants, insects and animals,
Severely cloud the results.
To combat this, focus is
switched to the victim's inner teeth.
Scientists reckon that the
best way of looking at the dna
Of a blood-borne pathogen,
is to look at the tooth pulp.
Because the tooth enamel will protect that
From external contaminants.
After looking at the dna samples,
There are several thousand
different bacterial species.
Finding the one that may have
been the killer is a daunting prospect.
To crack this case, they need
a large-scale screening process.
[narrator] this crucial
breakthrough comes in 2016
Via a new generation
of bio-informatics tech.
The megan alignment tool or malt.
So, what's really, really cool
Is that it has completely
revolutionized ancient dna research.
What scientists do is they take
All of the strands of dna
that have been sequenced
And use a computer program
To, basically, say, "right, where
is this dna sequence from?"
And match it against databases of known
Modern, uh, bacterial dna sequences.
Essentially, sifting through
all the information for you
To find tiny bits of evidence of pathogens
That were previously hidden to us.
[narrator] malt crunches the
data from these new samples,
Screening for any
hint of a killer pathogen.
The sequencing discounts
the usual suspects.
Smallpox, measles, flu.
But it does land on one suspect.
In a few teeth, they find pieces of dna
From salmonella enterica.
The cause for enteric fever.
[narrator] crucially, enteric fever
matches many of the symptoms
Described during the cocoliztli epidemic.
Until this discovery among these skeletons,
Nothing was actually
known about the prevalence
Of this particular pathogen
In the past and among these people.
Cutting-edge science has
now been able to identify
The bacteria that was
part of this huge epidemic
And decline in this population.
[narrator] but one mystery remains.
How did this deadly pathogen flare up
In 16th century mesoamerica?
Scientists run the same tests on burials
That pre-date european contact
And find no example of enteric fever.
The blame for this disease falls
squarely on spanish colonizers.
It's thought that the europeans
carried the bug to the americas
Through livestock or
through human carriers.
Once in the americas,
It would leech into the
food and water supplies
Through vomit and fecal
material of sick individuals.
It would then spread and ultimately kill
Millions of the central
american population.
[narrator] having cracked
this centuries-old case
At teposcolula-yucundaa,
Next generation genomic analysis
Is being touted as the pathogen pioneer,
A crucial bio-informatics tool
For unlocking our hidden
disease-ravaged past.
[king] many historic diseases
were absolutely catastrophic.
I mean, they collapsed cities.
Entire populations were decimated.
But now, with this cutting-edge science,
We can understand more about
how these deadly pathogens
Have shaped human history.