Original subtitles

[narrator] revolutionary microbiology

Investigates the medieval undead.

[sheila hoffman] placing the stone in the child's mouth

Was to prevent them from coming back to plague the living.

[narrator] chemical fingerprinting,

Decodes a roman terror weapon.

Hundreds of these sling bullets raining down.

It would scare the daylights out of anyone.

[narrator] genetics helped trace the new human species

Responsible for stunningly sophisticated jewelry.

It doesn't make any sense. Who was using these techniques

Tens of thousands of years ago?

[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] mt. Llullaillaco, argentina.

1999.

Near the summit of the world's second highest active volcano,

Archeologists find three mummies in pit tombs.

It's an extraordinary setting. A towering volcano,

Containing three small figures.

They're frozen stiff by the frigid mountain climate.

A natural mummification.

The level of preservation is astonishing.

It's like they almost died yesterday.

The scene is unbelievably eerie.

There's no obvious wounds or a cause of death.

The circumstances are really bizarre.

[narrator] over the next decade,

A battery of science and high tech

Pieces together these children's stories,

To reveal how they met their chilling end.

An extraordinary amount of effort must've been put into

Placing these children here up on this mountain.

22,000 feet above sea level.

How did they end up entombed in this remote volcano

Hundreds of miles from civilization.

[narrator] this baffling discovery makes mt. Llullaillaco

The world's highest archeological site.

Analysis of the three tiny figures

Shows the oldest is a 13-year-old female.

She's given the name, maiden.

Accompanying her is a younger boy and a girl.

She displays horrific facial burning.

[karen bellinger] the girl's ear has been melted off.

It looks as if she's been struck by lightning right in her grave.

In fact, researchers call her the lightning girl.

[narrator] alongside these victims is a stunning array of grave goods.

Including gold and silver figurines, fine pottery

And exquisite textiles.

All protentional clues to their deaths.

It has all the hallmarks of a ritualistic burial.

But why build these tombs at these dizzying altitudes.

It's deeply mystifying.

[narrator] first, samples from the children are radiocarbon dated

To determine which culture they came from.

A sample of the maiden's hair dates to the middle of the inca empire.

So that helps shed some light on this mystery.

This leads us away from some kind of burial custom

And more toward sacrifice.

[narrator] during the 15th century ce,

Young children gave their lives to inca gods

In times of stress, called capacocha.

This ritual was often performed on sacred mountain tops.

But in this case, there's something amiss.

[carla valentine] now a really big telltale sign of human sacrifice

Is how the person died.

We know the inca used brutal methods.

Some common methods might be strangulation or a blow to the head.

But this does present another mystery.

These children appear undamaged and at peace.

The maiden is healthy, well nourished

And even her posture seems relaxed.

[bellinger] it looks as if she's just nodded off.

It's pretty poignant actually.

[narrator] closer analysis of the artifacts adds yet more intrigue.

The maiden's headrest feathers hail from the amazon jungle.

While figurines are made of spondylus shells,

That originate over 100 miles away on the coast.

We can see that these are very high status objects.

These are associated with the inca elite.

One of the things you might ask is,

Are these children then members of the elite themselves?

Are they royal children and that's why they have such extravagant grave goods?

[narrator] to help untangle this mystery,

The mummies are taken to argentina's institute of high mountain research.

With collaboration from the european universities of bradford and copenhagen,

They're extensively tested.

So, what really jumps out is the level of preservation.

Everything from fabric and textiles to plant remains

To fingernails and hair.

The organs are undamaged and there's even blood left

In the chambers of the heart.

[narrator] some content of the digestive tract also remain

And can be analyzed.

Looking at the food content in the stomach and the intestines

Gives us more clues about the children's death.

[hassett] from the maiden's stomach, we can see that

She probably had her last bit of food between two to seven hours

Before she actually died.

And looking at her rectum, we can see that she hadn't defecated after eating.

She wasn't in any great state of distress.

The artifacts placed around her weren't disturbed.

So the evidence suggests that the maiden actually did die,

In position, in her tomb.

[narrator] but still, the cause of her death remains unclear.

Learning how the maiden died on this bleak mountain top

Is key to solving this mystery.

[narrator] researchers hope a ct scan will shed more light on the maiden's demise.

This is given to the digital forensics lab

For pathologist carla valentine to scrutinize.

What I have here is a digital visualization

Of the maiden's ct scan.

It let's us thoroughly examine the skeleton for any hidden trauma.

Let's zoom-in for a closer look.

There's no obvious fractures. She seems pretty healthy.

But our digital model does reveal something extraordinary.

Something you would not expect to find in the mouth of a child.

It's this curious object clenched between the maiden's teeth.

It's a bundle of coca leaves called a quid.

And users will get a narcotic high from chewing this.

Effectively, it's just unprocessed cocaine

And has the exact same effect as the powdered form.

Which suggests the maiden may have been drugged in her final hours.

Why on earth would anyone do this to a child?

[narrator] more disturbing,

This wasn't the only intoxicant forced upon these young children.

We also find evidence of alcohol consumption in all three children.

Likely a maize based beverage called chicha.

The cocktail of coca and alcohol probably made them pretty out of it.

[narrator] in argentina, three amazingly preserved child mummies

Were found on a volcano summit.

Advanced tech has proved the oldest, named the maiden,

Was drugged before death.

Investigators suspect it may be linked to child sacrifice.

To dig deeper into this substance abuse,

They analyzed the maiden's hair.

Hair is like a chemical diary. Traces of what we eat are locked inside.

Even 500 years later, we can find out what they ingested.

And the longer the hair, the further back in time we can look.

The maiden's hair is over eight inches long

And represents about two years of growth.

[narrator] chemical traces are extracted from strands of her hair.

These are purified

And then identified using a mass spectrometer.

The evidence from her hair shows that about 12 months before she died,

She had a massive increase in consumption of coca.

It's likely that this was used as a sedative.

It was certainly not enough to kill her.

We also find evidence of alcohol consumption in all three children.

Likely a maize based beverage called chicha.

And we also find cups that probably would've contained this chicha

Buried with the children.

[narrator] all the evidence points to a rare form of incan ritualistic sacrifice.

One that shuns a horribly violent death for something more merciful.

What would've been a potent cocktail of drugs and alcohol in these kids' systems,

Probably meant they wouldn't have had a clue what was going on.

One could look at this particular ritual as a form of euthanasia.

These children would've become important intermediaries

Between the worlds of the living and the dead,

But equally they serve as a key reminder

Of the importance of paying tribute to the inca emperor.

[narrator] the three child mummies are now on display

At argentina's museum of high altitude archeology.

All are a permanent reminder of capacocha.

These sacrifices had a hugely important role in inca society.

It was part of how they maintained their power and legitimacy.

[narrator] the altai mountains, southern russia.

Archeologists excavating a remote siberian cave make an extraordinary discovery.

Deep in the gloomy shadows of this cave, there are tens of thousands stone age artifacts

Lying on the floor.

[mark horton] archeologists find remains of bone

As well as worked jewelry artifacts.

These are items that have been turned into obviously personal ornaments

Of one type or another.

[allan maca] the jewelry includes ostrich eggshell beads.

Stone and bone pendants.

Among all these incredible objects there's one that stands out above all others.

And it's a carved stone bracelet

Made from a very hard green stone.

[narrator] more eye-catching,

The bracelet contains a finely bored hole.

Compared to the other stone age items,

It appears at least 30,000 years more advanced.

The ability to polish this stone,

To carve this stone and to also bore a hole in it...

This suggests a great technological sophistication.

It doesn't make any sense.

Who was using these techniques tens of thousands of years ago?

[narrator] for nearly a decade, no one could answer that question.

Now, cutting edge analysis hopes to explain

Who made this sophisticated bracelet.

[maca] in a way, this doesn't really make sense.

This really baffles the mind.

[narrator] the denisova cave containing this discovery

Nestles in the altai foothills near russia's southern border.

It's been a vital refuge, spanning 300,000 years of human history.

[horton] now this is right in the center of asia.

And it's very dry and very cold up there.

So the cave deposits survive very well.

[narrator] to understand who could've crafted the green bracelet,

Archeologists first need to determine what era it came from.

Because it's made of stone, we can't really carbon-date it

'cause there's no carbon in the stone.

So the only way we can date it is work out a stratigraphic position in the cave

And date deposits that are immediately adjacent to it.

[narrator] scientists test the sediment layer the bracelet was retrieved from, using osl.

Optically stimulated luminescence.

Optical dating is a way of figuring out when minerals in the earth

Were last exposed to sunlight based on the energy stored inside.

[narrator] the result is beyond anyone's wildest expectation.

We know from dating the soil deposits around it,

That this bracelet is probably 40,000-50,000 years old.

This is remarkable.

Especially considering the advanced techniques needed to make it.

[narrator] 50,000 years ago, early humans possessed crude stone tools.

[maca] there're things like scrapers, spear points.

Cutting tools in the stone age or paleolithic period.

[narrator] it seems inconceivable

These could've created this bracelet's precisely bored hole.

So experts check the dating accuracy via another method.

Some other ornaments found in the cave are made out bone and ivory,

Which can be radiocarbon dated.

[horton] radiocarbon dating these personal ornaments had come out about

43,000-45,000 years ago.

So again, they seem to confirm what the osl date is.

This bracelet is extremely ancient.

[narrator] this revelation deepens expert resolve to track down the early humans

Who crafted this bracelet.

One species is immediately ruled out.

[koons] we know that homo sapiens were in eurasia

Around the time the bracelet was made.

But the evidence is telling us that it is not homo sapiens

Who were occupying the cave.

[narrator] instead, the spotlight falls on the neanderthals,

Known to have dwelled in this region.

The neanderthals were a relative of humans who lived in europe and asia

Until they became extinct about 40,000 years ago.

We do know that neanderthals made art and jewelry,

For example, in croatia, archeologists have found modified eagle talons.

[narrator] so could this green bracelet have been fashioned by neanderthals?

Some bone fragments found with cave artifacts should provide the answer.

Scientists use advanced genomics to trace their origins.

Scientists extract the dna from the bones,

Sequence it and compare it to databases

Containing sequences from other early human species.

Some of the bones clearly belonged to neanderthals.

But some of the bones still can't be identified.

[narrator] these mystery bone samples share commonalities with neanderthals.

Enough to raise a mind-boggling prospect.

There are some similarities between the mystery dna and neanderthal dna.

It suggests we could be looking at a completely new sister species.

[narrator] in russia, investigators are trying to trace the early humans

Believed to have made a sophisticated stone bracelet.

But dna analysis of bones found in a cave with this precious item

Have only deepened the mystery.

[koons] we know that neanderthals inhabited the cave.

However it looks like another species lived here too.

[narrator] paleoanthropologists confirm

This is an entirely new human species.

It's named denisovan after the denisova caves of this discovery.

We know about modern humans coming out of africa.

And we know about neanderthals that are living in europe.

But here in central asia was a third species of early human.

It was one of the great findings of the decade.

[narrator] branching off from a common ancestor around 400,000 years ago,

Denisovans and neanderthals co-exist on the human

Evolutionary timeline.

But the question remains...

Which of these two species made the bracelet?

To find out, scientists use a next level dating technique,

Called "relative genetic aging" on the bone fragments.

We calculate relative genetic ages by comparing the dna from these cave dwellers

To other human fossils and counting the differences between them.

Mutations accumulate at a known rate in modern humans.

So we can use that rate

To figure out how old these ancient humans were

Based on the number of mutations that have accumulated in their dna.

[narrator] applying a complex statistical model

Finally provides an answer.

The youngest hominin fossil found in the cave dates from 52,000-76,000 years ago.

Unfortunately, it's a real drawback.

This is thousands of years before the bracelet was made.

[narrator] it's hugely frustrating.

Results show the denisovans occupied the cave

Some 50,000 years longer than neanderthals.

But not enough to crossover with the bracelet.

Experts believe they remain the prime suspect.

[maca] recent analysis of the finger bones of denisovans

Shows us that they apparently had better manual dexterity than neanderthals.

Which may explain how they might be the ones responsible

For fabricating the beautiful stone bracelet.

[narrator] hopefully new evidence will come to light proving this bracelet

Is indeed denisovan handiwork.

Heavens knows what new discoveries will be made in the future.

At the moment we know so little about them and their

Intellectual capabilities and what they're able to do,

We really can't speculate.

I'm still rooting for the denisovans.

And I think many archeologists will be too.

[narrator] the state of yucatan, mexico.

Deep in the jungle,

In the ancient maya city of chichen itza

Lies one of the most mysterious sights in the americas.

The temple of kukulkan.

This imposing temple is dedicated to their plumed serpent god.

And it just sprouts right out of the jungle.

It's a testament to the art and architecture and the amazing building skills

Of the ancient maya.

However, even today there's surprisingly little we know about much of this building.

[narrator] this 1,000 year old temple

Dedicated to the maya god of the wind, sky and sun

Is one of the new seven wonders of the world.

[sascha auerbach] along with the great egyptian pyramids,

This temple is the most famous and impressive pyramid of the ancient world.

But it's still a mystery to us why it was built here.

[narrator] now, cutting edge 3d mapping will reveal clues

Hidden underground

That could finally unlock the secret to kukulkan's location.

This new discovery has the potential to rock

Mesoamerican archeology to its core.

[narrator] for centuries,

Kukulkan has fascinated the world.

The maya are renowned for creating complex calendars,

Often integrated into their architecture.

Kukulkan is the most famous example.

[bellinger] kukulkan has 91 steps.

Plus one more at the temple on top.

If you multiply that by the four corners,

You come up with 365.

It's the number of days in a calendar year.

[narrator] an additional phenomenon also connects

The temple to the passing seasons.

One of the most surprising and spectacular pieces of evidence

Reveals during the equinox.

[narrator] during the March and September equinoxes,

The god kukulkan appears to manifest from out of thin air.

As the sun begins to set on these two days

A serpent appears to slither down the northern staircase of the monument.

The maya would see this play of light and shadow as the actual god kukulkan.

[narrator] this deity apparition leaves little doubt to the temple's purpose.

But is there a reason for its location?

Investigators suspect the region's remarkable geology offers a clue.

[thunder rumbling]

When it rains we expect that water to run off

The surface and collect in rivers.

But that doesn't happen in yucatan.

The yucatan peninsula with chichen itza and kukulkan belt

Has no rivers on its surface.

[narrator] the rocky landscape is riddled with fissures

Funneling rainwater into underground caverns

Known as cenotes.

Chichen itza means "at the mouth of the well of itza".

The city is full of sinkholes and cenotes which hold water

That can be then be used for drinking or irrigation.

[narrator] but cenotes hold an even deeper importance.

These cenotes

Were believed by the mayans to be portals

To the underworld that was inhabited by the gods.

Among the most important of them being chaac.

The god of life-giving rain.

[vranich] the maya believed that chaac

Held the waters of the world in these large clay pots

And the sound of thunder were these pots being broken open to release the rain.

[narrator] experts consider whether these watery caverns

Now hold the key to this centuries old kukulkan mystery.

[auerbach] cenotes are so absolutely crucial to the mayan worldview

And to their understanding of the cycle of life and death.

Kukulkan might have been arranged

Specifically based on the placement of the cenotes.

Kukulkan could have a deeper, darker purpose than we ever expected.

[narrator] in yucatan, mexico,

The stepped pyramid kukulkan

Is one of the great mysteries of the mayan empire.

Experts believe there's a hidden reason for its precise location.

But nearly 100 years of archeological searching

Have drawn a blank.

This is one of the most famous monuments on earth.

But it's still somewhat of a shrouded mystery.

[narrator] in 2014,

The shallow geophysics group from the national autonomous university of mexico,

Combined forces with the national institute of anthropology and history.

They attempt a new survey

Using electrical resistivity tomography.

This is a method by which you place a series of spikes in the ground

And pass electrical current through them.

And that current goes into the ground

And bounces off things that are below the surface.

And as you do a series of these,

You can build up a 3d image of what

The buried substrata look like.

[narrator] the team had to develop a special non-invasive method

To protect historic kukulkan.

Their efforts pay off.

It's a first survey of its kind,

To produce a detailed 3d image of the temple.

In the digital lab,

Historian sascha auerbach is given privileged access.

Academics are really excited about this survey.

It should open a new, hopefully revolutionary perspective.

Let's add the tomography results.

Look at that. Look at how that big blue space stands out.

Now in this survey, blue denotes extremely low electrical resistance.

Far too low to be dirt or rock.

What we're looking at is a watery cavern,

Also known as a cenote.

This also looks like a pretty sizable one.

Using my digital measuring tool,

We can see that it's 114 feet at its widest

And it's over 65 feet deep.

Quite amazing.

Now we go back to our digital map, we see something else.

As we pull out, two more cenote.

One to the north and one to the south.

But it doesn't stop there.

If we pull back a little bit farther,

We'll see that there are two more of these cenote.

One to the east and one to the west.

Now let's connect them.

Look at that.

The great temple of kukulkan sits at the epicenter

Of the maya spiritual universe.

This is truly remarkable.

The equivalent of the sepulchre for christians

Or the kaaba for muslims.

The holiest of places in the maya civilization.

[narrator] after centuries of mystery,

The discovery that kukulkan was aligned with the cenotes,

Reveals this temple is not just a calendar.

It's a portal, through which they communicated with the gods of the sky,

And underworld.

The temple of kukulkan and the cenote beneath it,

Are the center of the axis mundi

Or the center of the world for the ancient maya.

The place where the maya ceiba tree of life was planted.

The branches of the ceiba reach up into the sky.

They represent the upperworld.

The body of the ceiba is this world where the humans live

And the roots of the ceiba extend down into the underworld.

And so the ceiba tree links together the three worlds

Of maya cosmology.

[narrator] umbria, central Italy.

Archeologists from the university of arizona

Are excavating the necropoli dei bambini,

Otherwise known as the children's cemetery.

It dates to the fifth century ad,

And in the ruins of this villa

Were a number of child burials,

Including fetuses and young children.

[narrator] among piles of bones,

The team makes a heart-stopping discovery.

[kiki sanford] there's a skeleton of a child,

Lying on its side, and a brick has been forced between its jaws.

I have never seen a child buried like this.

This is a really unusual burial phenomenon,

In an extremely emotive context.

[narrator] some suspect this is a portent of the evil undead.

According to classical texts, the unusual burial practices such as this,

Were reserved for individuals who they believed were the unquiet dead.

It counsels the living to place a stone in a child's mouth to prevent them

From causing harm to others, after they become a revenant.

Someone who comes back to life.

The idea being

The soul of the dead individual passes out through the mouth

And haunts the world.

[narrator] now, revolutionary science investigates why this child

Suffered such harsh treatment in death.

We have to understand that the mid-fifth century here in Italy

Is a time of upheaval.

But, what could possibly explain such a disturbing burial of a child?

[narrator] in 2018, archeologists excavating an italian children cemetery

Uncover a sinister makeshift tomb.

Inside, a small corpse has a stone wedged in its mouth.

The burial site is creepy as hell.

[narrator] rubble is scattered across the skeleton.

So initially they consider if the stone accidentally fell into the mouth.

Natural jaw opening, as the muscles decompose,

Is actually quite common and it's found often in bodies that are in coffins.

But it's much less likely in bodies

When they're lying on their side.

It looks like the jaw has been intentionally forced open.

[narrator] further analysis of the stone confirms this was a deliberate act.

The stone in the child's mouth has a real crystalline sheen to it.

It's obviously not the same as the stone used for masonry nearby.

This is not a random occurrence.

[horton] also seems to have some evidence of shaping,

Possibly in order to fit inside the person's mouth.

[narrator] having established foul play,

Forensic anthropology helps build a victim profile.

Initial examination of the skeleton can't tell us if it's a male or female.

But, based on the dental eruption of the teeth,

We can tell that this child was about eight to ten years old when it died.

[narrator] but curiously, investigators can find no skeletal evidence

Why this young child was so badly treated.

They widened their search for material clues.

So, in this cemetery, there are a number of other finds that

We might consider really quite creepy.

There are raven talons, toad bones, cauldrons,

Bits of ash and signs of burning, and even sacrificed puppies.

[horton] what's interesting is with this array of what appear to be cult-ish objects.

That maybe, you know, some idea of magic

Or something supernatural, maybe being going on here.

[narrator] it bears the hallmarks of paganism.

In fifth century Italy, christianity has taken root.

Anyone displaying idolatrous beliefs is savagely persecuted.

The stone in the mouth may have been a supernatural safeguard.

The mid fifth century is a significant time.

We are right at the cusp of the medieval period.

Many of the smaller towns and villages

Still retain their folkloric and superstitious practices.

There was a deep fear of the undead.

The notion that people wouldn't properly die and go to the underworld,

But their souls, their spirits would stay in a state of suspended animation

To haunt the present.

So if you can insert a stone in the mouth,

Would let you block the spirit inside the body when you bury it.

Then you can avoid the whole issue of undead.

[narrator] but any thoughts this child was possessed are banished

When scientists analyze the cemetery's charred deposits.

Sprinkled around the burial site,

There are several patches of what look like

Small grains of charcoal. But under a microscope, we can tell,

This is the remains of honeysuckle.

It must've been important. They were sprinkling it all over the place.

[narrator] records reveal, this sweet smelling flower

Was once regarded as an important panacea.

[horton] in the ancient world, honeysuckle was not only a cleanser,

But was also seen as a medicine to salve diseases,

Internal diseases particularly for spleen.

[narrator] armed with this knowledge,

Scientists re-examined the child's skeletal remains for evidence of disease.

The child lost a tooth before they died.

It appears to be the result of a periodontal abscess,

Which is a pocket of pus in the tissues of the gum.

Several diseases are linked to children getting periodontal abscesses like this.

Chicken pox, measles and malaria.

Most importantly we know it's a disease that causes an enlarged spleen.

[narrator] to check for malaria, a ground-breaking test is used on bone samples

Taken from the cemetery.

The malaria parasite excretes hemozoin,

Which you can actually find by using x-ray diffraction techniques.

Going into the bones and cells to identify this molecule.

When you look at the results, you see these big, black, crystalline lumps.

And that is a very clear sign that this is malaria.

[narrator] malaria in cemetery samples, together with historical accounts of

Regional pestilence suggests a huge local outbreak of the disease.

And helps explain why a stone is jammed in the child's mouth.

The physical symptoms of malaria can be quite terrible.

I mean, imagine watching a child go into an open-eyed coma and start convulsing.

You can completely understand why ancient people would have prescribed this

To malignant supernatural forces.

Placing the stone in the child's mouth was both a literal

And symbolic way of incapacitating the child and keeping them

From coming back to plague the living.

[narrator] southern scotland, united kingdom.

An ancient iron age hillfort flanked by two unusual roman camps,

Has flummoxed experts.

On the north, the imprint of the roman encampment doesn't follow the standard,

Symmetrical rectangular plan. It's strangely elongated.

And to the south, this encampment is wonky,

And has three wide gateways, facing the hill.

[narrator] adding intrigue, during the 1960s,

Archeologists discover a huge pile of slingshot

Strangely accumulated at the hillfort entrance.

These are small pieces of lead used as projectiles

By roman infantry men who had slings.

We know the romans were obsessed with training.

And the fact that these slingshots

Were concentrated towards the gate suggesting that maybe they're out there practicing.

A sort of target range if you like.

[narrator] for three centuries this ancient hillfort has been a source of controversy.

Some scholars suggest that this is the site of a roman training camp,

And others actually have studied it

And say, "no this is the place, the site of a brutal siege."

[narrator] now it's hoped a unique archeological discovery

Will finally settle this mystery and reveal what actually took place

At burnswark, 1,900 years ago.

It's a mystery that has permeated decades of research and still

People are trying to resolve what really happened here.

[narrator] in burnswark, scotland, an iron age hillfort,

Pincered by two oddly configured roman camps has divided archeologists.

- Some believe it's a training site. - [soldiers shouting]

[narrator] others, a battlefield.

It's a mystery that has baffled scholars for ages.

[narrator] in 2015, investigators revisit this former stronghold

- Of the caledonian selgovae tribe. - [tribesmen shouting]

[narrator] they attempt to crack this half century riddle

With battlefield archeology and modern technology.

Battlefield archeology was developed to better understand

Kind of, civil war sites

And battlefields by using sensitive metal detecting

To look at the distribution of musket balls across the site.

But it works in the same manner to survey roman battlefields

For sling bullets and arrowheads.

[narrator] a survey of the 17 acre site reveals far more than anyone bargained for.

Literally thousands of metal objects scattered across the landscape.

[narrator] a third of the finds are roman sling bullets,

Most of the standard lemon or acorn shape.

But there's also a new radically different type.

These are very unusual objects.

They were smaller than your standard sling bullets.

These artefacts are about an inch long and they weigh less than an ounce.

What's really interesting about them is that they have a small hole

Bored into one side.

It's very clear that these are specifically engineered, but for what and why

Has been baffling.

These perforated bullets may be the key

To finding out what really happened here at the hillfort.

[narrator] the only way to determine their true purpose is to test them.

- As they take flight, all hell breaks loose. - [whistling]

What they discovered is that these objects created this high pitched whistling,

And they have what's called an aerophonic quality.

Hundreds of these sling bullets raining down made a cacophony of sound.

-[whistling] -it would scare the daylights out of anyone.

[dills] they were nearly invisible in flight.

So you didn't know when and where they were going to hit.

They would have been used to create terror and chaos.

[narrator] this astonishing revelation undermines the theory

That burnswark was a roman training camp.

The modified holes represent an additional step in the manufacturing process.

This is additional labor. It would be unusual to use

Valuable ammunition like this, just for practice.

It now seems likely that a merciless siege

Or at least a major skirmish occurred right here.

[narrator] but conclusive proof is needed.

That requires somehow dating these whistling shots to the roman era.

[horton] we can't directly date these slingshots because they're made of lead,

They're not made of carbon. So you can't use radiocarbon dating.

But what we can do is compare them to other sites

Where slingshots have been found.

Sites that are directly dated to this period.

[narrator] isotope analysis is used to chemically fingerprint the slingshot.

This is cross-checked against catalogued roman shot to get a match.

The bullets from the burnswark site have the same signature as bullets found

At a nearby roman site called birrens.

Now, in birrens, these bullets

Were excavated in a context that allowed us to date them

From the antonine period.

This is the reign of the emperor antoninus pius.

[narrator] antoninus pius is regarded as the emperor of peace and prosperity.

His reign characterized by vast construction projects.

In 142 ce, he orders the building of the antonine wall,

To keep raiding caledonian tribes at bay.

[horton] the romans had a problem in defending their frontiers.

A decision was made to extend the roman empire northwards from hadrian's wall,

To the link between the plate and the four estuaries

And to build a new wall between the two to annex southern scotland

Into the roman empire.

This puts the roman army on a collision course with the burnswark hillfort.

[narrator] burnswark is occupied by the selgovae tribe, meaning the hunters.

These fearsome warriors demanded rome's most formidable terror weapon.

Thousands of these slingshots whistling through the air.

This must have been quite terrifying.

These sling bullets are an incredible find and show us how important it was

For the romans to take this hillfort.

They were willing to employ their most innovative weapons to expand their empire.