Original subtitles

Narrator: A grizzly discovery made on Chile's highest peak

reignites an unsolved mystery.

Dr. Leonard: Her jacket is unzipped,

and her hands are bare.

Strangely, there's a rock on her, in an ice field.

James Ellis: But her injuries don't seem

to be consistent with a fall.

Is it possible that she was the victim of foul play?

Narrator: Researchers make a strange discovery

in Iceland's arctic fjords.

Dr. Riskin: It's got purple bones!

That is super weird.

What could possibly make bone...turn colour?

Narrator: Archaeologists uncover a macabre discovery in Sweden.

Dr. Cantor: Beneath the rock formation,

they find seven well-preserved tombs

with intact skeletons inside.

So, who were these people and why are they buried together?

Narrator: These are the strangest mysteries,

trapped in the coldest places.

Lost relics.

Forgotten treasures.

Dark secrets.

Locked in their icy tombs for ages.

But now, as ice melts around the world,

their stories will finally be exposed.

♪♪

♪♪

♪♪

Narrator: Located in West Central Argentina,

on the Chilean border,

Mount Aconcagua is the tallest mountain in the Americas,

reaching a height of almost 23,000 feet.

Dr. Leonard: Aconcagua is a Quechua word that translates to

"Sentinel of Stone".

It's one of what we call the Seven Summits of the World,

which are the tallest peaks on each of the seven continents.

These mountains attract climbers and adventurers

from all over the world.

James Ellis: The summit of Aconcagua was first reached

in 1897 via a route now known as the Normal Route.

There's more than one way to climb a mountain though.

And in 1934,

a group of Polish climbers made a far more dangerous ascent,

scaling a 2,000 foot glacier in the process.

That glacier is now famous

and goes by the name of the Polish Glacier.

Dr. Riskin: Aconcagua is often considered one of the easier

climbs of the Seven Summits, so some people take it

on as preparation for the bigger mountains like Everest.

But it is no walk in the park!

More than a hundred people have died

on Aconcagua since records began

and there are more annual deaths here

than any other mountain in South America.

Narrator: In 1975, three climbers were descending

Mount Aconcagua, when they came across something

out of place on the Polish Glacier.

Anthea Nardi: From a distance, it looks as though it could be

some clothing or maybe a large backpack,

nestled among the rocks and ice.

Climbers leave things behind all the time,

so it wouldn't be out of the ordinary

to find something like that.

Narrator: Their curiosity piqued,

the men approached the object,

and came to a horrifying realisation.

Dr. Leonard: It's a body!

Given the condition, it's been here for a while.

And based on the size - probably a woman.

Her face is battered and blackened with blood stains,

and ropes are tangled around her body.

Her jacket is unzipped, and her hands are bare.

Strangely, there's a rock on her...in an ice field!

Narrator: Some 45 years later, in February of 2020,

two porters are securing ropes on the Polish Glacier,

in preparation for an upcoming expedition,

when they spot something poking out of the ice,

glistening in the sun.

Dr. Riskin: Thankfully, not a dead body this time.

It's a camera!

Now, it's not unusual to find abandoned,

or lost equipment in the ice.

Climate change is causing glaciers all over the world

to recede, and we're finding all kinds of stuff on mountains

all over the place. But a camera does stand apart,

because most climbers won't leave something valuable

like that behind. So whose camera is this?

What is it doing 20,000 feet up the mountain?

And does it have any pictures on it?

Narrator: Moving in for a closer look, one of the porters

removes the camera from its icy resting place.

Anthea Nardi: It's a 35 millimeter Nikomat.

The lens is badly cracked and the dial at the top shows

that it has taken 24 pictures.

It was even wound, ready to snap the next photo.

It's obviously quite old, but

its exact age is difficult to determine.

Dr. Leonard: The Nikomat was introduced by Nikon in 1965,

as a more affordable consumer-level alternative

to its professional 35 millimeter models.

It was well known for its durability,

and even saw use during the Vietnam War.

So this might explain why someone

brought one to Aconcagua.

James Ellis: Nikon discontinued production of the Nikomat

in 1978, so we know this camera must have been made

between then and 1965.

But that still doesn't tell us when it was left

on the mountain, or by whom.

Narrator: Clearing the debris off the camera,

the porter notices that it's nestled in a leather holster,

with a thick strap.

And punched into blue embossing tape stuck to the holster,

is a name and address.

Dr. Riskin: It reads: Janet Johnson,

1259 York Sreet, Denver, Colorado.

That is the woman that the climbers found dead

on this mountain in 1975.

So we know whose it is, but now the question is,

might the pictures on that camera offer some clues

about how she died?

Narrator: On January 20, 1973,

an expedition of eight American mountaineers

set off on an attempt to reach Aconcagua's summit.

Anthea Nardi: The team originally consisted of

a lawyer, a psychiatrist, a doctor, a dairy farmer,

a college student, a police officer,

and a NASA engineer named John Cooper.

All were men and mostly weekend climbers.

Then, at the last minute Janet Johnson joined the expedition.

Dr. Leonard: Janet was probably the most experienced climber

of the group. By the age of 30,

she became one of the first 20 women to reach the summit

of each of Colorado's 58 "fourteeners",

These are the peaks higher than 14,000 feet

in elevation in the state.

James Ellis: Janet was adopted and during her college years,

her mother found out she was gay,

and tried to 'cure' her

by sending her to a hospital.

Janet's sister would later say

that she was trying to prove something to her mother,

by climbing the highest mountains.

Dr. Riskin: John Cooper was also an adventurer,

with a decent amount of climbing experience.

But what made him famous, is that he worked for NASA,

and he was in mission control during the Apollo 11 flight,

that put Neil Armstrong on the moon.

Narrator: The expedition garners interest from the

local Argentinian newspapers because there is a woman,

a rarity for the time,

and a NASA scientist in the group.

The fact, that they also intend to take

the more perilous route up the Polish Glacier,

makes the story all the more captivating.

Dr. Leonard: The expedition gets off to a rocky start.

It's a gruelling climb from basecamp to Camp 1,

which sits at 15,500 feet above sea level.

Suffering from altitude sickness,

three members of the party decide to stay here,

while the rest continue up to Camp 2,

at roughly 18,000 feet.

The trek to Camp 2 takes seven hours,

and the five remaining climbers make it up safely.

James Ellis: Then they plod upwards to the base of

the Polish Glacier and establish Camp 3,

at 19,400 feet.

Another person gets sick, and their Argentinian guide

takes him back to basecamp,

leaving only four team members at Camp 3.

Police officer Bill Zeller,

dairy farmer Arnold McMillen,

Janet Johnson and John Cooper.

This is when things take a turn for the worse...

Narrator: The decimated team digs a small snow cave

on the glacier with their ice axes.

And since they have no sleeping bags,

they lie down on reflective space blankets,

and prepare to spend the night.

Dr. Riskin: Cooper can't take the cold.

And right before the sun comes up,

he suddenly announces that he is going back to Camp 3, alone.

That is very risky and it really shows

that he's a bit of a weekend warrior,

who got in above his head.

No seasoned mountaineer would ever take that kind of a risk.

Anthea Nardi: Shortly after Cooper's departure,

the remaining three climbers decide to trudge on,

but it's slow going and arduous.

The snow is waist-deep and by the time

they get near the summit, darkness already has fallen.

Dr. Leonard: At some point, the two men look back and realise

that Janet Johnson isn't with them,

so they scramble back down and they find her

lying in the snow, exhausted.

According to their accounts,

she surprised them by asking to be left there to die.

She had basically given up.

But they aren't about to leave her there, so they help her up,

and attempt to take her back down the mountain.

James Ellis: This is where the story gets messy.

They begin to suffer from altitude sickness,

hallucinating, and hearing voices.

Narrator: The next morning,

they manage to return to the snow cave

where they find a flare gun and shoot it off.

The trio decide that McMillen should head down

to basecamp alone, in order to get help.

On the way, he begins hallucinating

that the Argentine army is coming to rescue him.

He also thinks he sees a dead soldier in the snow.

Dr. Riskin: The dead soldier is real, but its not a soldier,

it's John Cooper, dead on the mountain.

Anthea Nardi: On the Polish Glacier, Zeller and Janet

are separated by a bad fall,

and when Zeller doubles back to make sure she's ok,

he discovers John Cooper's body.

He then continues down the mountain to Camp 3,

leaving Janet to return, once she gets her wind back.

But, she never makes it.

Dr. Leonard: At this point, all we have to go on

are the accounts of Zeller and McMillen,

but given the hallucinations,

it's sort of like a novel with an unreliable narrator.

The question is, are they telling the truth

or their version of it,

or did something sinister happen on Mount Aconcagua?

Narrator: Immediately after their descent,

the two men are questioned by local authorities.

The tragic events are splashed all over the news

back in the United States.

But certain things aren't adding up

and an investigation is launched.

James Ellis: A team is sent up the mountain

on a recovery mission and they find John Cooper's body

150 yards from Camp 3.

He is completely frozen,

hands bare across his stomach.

Unfortunately, they're unable to locate Janet Johnson.

Narrator: John Cooper's body is taken for an autopsy,

which yields some shocking results.

Dr. Riskin: There's a hole in his abdomen,

and its got a wound so deep,

that it reaches all the way to his spine.

So one possibility is maybe he fell on his ice axe,

and then sat down to look at his injury,

lost consciousness and froze to death.

Anthea Nardi: But the coroner listed the official

cause of death as injuries to the skull and brain.

He also suspected that the wound to Cooper's abdomen,

could have been made by an ice screw.

So was John Cooper murdered?

And what about Janet Johnson?

Narrator: Two years later, after the climber's report

that they have found her body,

Janet Johnson's remains are extricated from the mountain

by a team of police officers and sent for examination.

Dr. Leonard: The autopsy reveals that she died of a brain injury.

Her face shows exposed bone in three places

and deep cuts on one of her boots.

This leads the assistant examiner to think

that someone may have hit her, hard!

James Ellis: And here's what's also strange.

According to Zeller, they were separated by a very bad fall.

And yet, Johnson's autopsy shows no broken bones,

or other injuries consistent with an accident like that.

Also, the area where the body was found is relatively flat,

not a dangerous slope where someone could

plummet to their death.

And what about the rock on her body?

Something isn't right.

Narrator: The medical examiner who performed the autopsies

on both Cooper and Johnson,

reaches an astonishing conclusion.

Dr. Riskin: They were murdered!

Their injuries were not the result of freak accidents,

this was a crime.

Anthea Nardi: Think about it. Both bodies had the most damage

to their faces, which is odd.

Johnson had no other broken bones

and her clothing wasn't torn.

Zeller reported that John Cooper likely died

from hypothermia and exhaustion,

but the coroner declared it was from head injuries

and he had a large hole in his abdomen.

But what I can't figure out is

what possible motive Zeller or McMillen

could have had for killing them.

Dr. Leonard: Strange things can happen on a mountain

when people are in a desperate situation,

fighting for survival.

Lack of oxygen and exhaustion can cause hallucinations

and erratic behaviour and drive people to do things

that they would never dream of in a normal environment.

James Ellis: Or, maybe they did die by accident.

They certainly wouldn't be the first people

to perish trying to climb a mountain,

and they certainly won't be the last.

We just don't know what happened.

But maybe the pictures on Janet Johnson's camera

can provide some answers.

Narrator: Incredibly, after nearly 50 years

frozen on the mountain,

the film in Janet Johnson's camera is sent to a lab

and they're able to develop the pictures.

Dr. Riskin: They're kind of heart-breaking to look at,

this is Janet and John in their final hours.

They're beautiful shots of the mountain,

you can see their fellow climbers.

But the saddest part is, they don't tell us anything

about what happened to them.

Only Aconcagua knows the answer to that and it's not talking.

Narrator: No one was ever charged in connection

with the deaths of John Cooper and Janet Johnson,

as Argentina fell into political chaos shortly after,

and the investigation fell by the wayside.

Cooper was interred in his hometown of El Dorado, Kansas

and Janet Johnson was buried in a small cemetery

near the trailhead of Aconcagua.

♪♪

Narrator: The mountain of Tap O'Noth

dominates the agricultural flatlands

of northern Scotland's Aberdeenshire.

Dr. Riskin: The winters here are kind of brutal.

Frequent snow, freezing temperatures

guaranteeing months of hardship for the people

that call this place home.

And it gets worse, the higher up you are.

The mountain's elevation guarantees

that the ground will be frozen solid,

and there will be tons of snow on the ground.

Anthea Nardi: Despite this fact, the summit does offer

some obvious advantages,

if we're speaking in a military context.

Rising 1,800 feet above sea level,

it guarantees a perfect vantage point

from which to observe the valley below.

And from here you can see people coming from all directions.

James Ellis: And at the top of the hill,

there is an ancient earthworks

that belonged to a fortification

that was built over a thousand years ago!

Narrator: The team of archaeologists

curious about the fort's past,

decide to investigate the site properly.

At the summit, the remains of earthworks measure

about the size of an Olympic swimming pool.

The earthwork itself is situated in the middle

of a 40 acre walled enclosure,

believed to be what remains of the fort's ramparts.

♪♪

Within this greater enclosure,

the archaeologists make a surprising discovery...

Dr. Leonard: They find some pieces of charcoal,

not necessarily an earth shattering discovery,

but when they're radiocarbon dated, the results show,

that the material is from the years between

the 3rd and the 6th century CE, meaning

the fort was occupied only 1,800 years ago at the latest!

Dr. Riskin: This is surprising because the fort was always

assumed to be way older,

from like the Bronze Age or the Early Iron Age.

Basically like 2500 to 750 years BCE,

that was a period with higher temperatures.

But the age of the charcoal means its much more recent

and it means, it was occupied during a mini Ice Age.

Anthea Nardi: This time period around the 3rd to 6th centuries,

was also a crucial era for the British Isles.

The Romans had invaded Britain in the first century CE,

and over the next 40-odd years, extended their empire

to about where the Scottish border is today.

The reason they couldn't get any further north,

and it wasn't from a lack of trying,

is because of a people known as the Picts.

James Ellis: We don't know all that much about them.

What we do know, is that the Romans feared them,

and called them Picti, meaning painted.

This was for the blue tattoos on their bodies

as they rode half-naked into battle.

Dr. Riskin: The fact that they abandoned what is now Scotland,

is an indicator of how much trouble the Picts gave

their would-be invaders. And keep in mind,

those Romans were basically unbeatable.

They took over most of Europe.

So, if the radiocarbon dates are anything to go by,

the fort on top of Tap O'Noth could be Pictish.

And if so, maybe that fort

could give us a clue as to how

that group managed to hold off the Romans for so long.

Narrator: Spurred on by their findings,

archaeologists enlist the help of LIDAR,

to scan the earthworks on Tap O'Noth.

Anthea Nardi: LIDAR is a technology

that basically lets us photograph and map

the earth's surface to an unbelievably accurate degree.

And not just that, it also allows us to see underground,

like we have an X-ray of the earth!

James Ellis: The LIDAR scanning of the mountain detects

more than 800 flattened areas

that are dug into the slopes,

all spaced very close together.

What are these things?

Dr. Leonard: The flattened areas also contain rounded holes

that are clustered around what appears to have been

a fireplace, or hearth.

My guess is that the rounded holes are postholes

that would have provided support for a roof.

So based on all this, these 800 flattened areas

are likely housing platforms!

Dr. Riskin: This is a game changer!

If we make a rough estimate and say,

maybe four or five people live in each of those dwelling,

then what we are looking at is a village,

surrounded by defensive walls.

And it's a village of up to 4,000 people!

Those numbers mean that the Picts may have been

way more capable of launching a military campaign

than we ever realized!

Narrator: The archaeologist's findings

warrant a full excavation of the fort at Tap O'Noth.

And they discover ceramic shards

that look like they belonged to a big and heavy

cylindrical vessel, with a handle on each side.

Dr. Leonard: These are the remains of Roman amphorae!

These were ceramic vessels made for easy transport of liquids,

like olive oil and wine.

And the fact that the Picts were using them shows us

that they had extensive trade networks

and they were interacting with a variety of people.

Dr. Riskin: Now here's the thing.

Amphorae are rare at Pictish sites.

So, researchers infer that since they're rare,

they are probably valuable.

And by extension, whoever has them

at these Pictish sites, must have been very powerful,

or very wealthy, or both.

Narrator: In 1978,

a local farmer dug up a stone carving,

featuring a bearded man with pointed teeth, carrying an axe.

It was dated to the time of the Picts,

and is likely one of the warriors feared by the Romans.

The carving is known as the Rhynie Man,

named after the area where it was found.

Anthea Nardi: Rhynie Man was found in the flatlands

just below Tap O'Noth, and its name is derived

from the Celtic word for King, "Rig".

In the same area, where he was found,

standing in a field is a solitary stone

with a carving of a salmon

swimming above some sort of beast.

It's known as the Craw Stane,

and it too was made by the Picts.

So there seems to have been quite a bit

of Pictish settlement in the area.

Narrator: Hypothesising that the two stone carvings

are evidence of a royal Pictish settlement,

the archaeologists excavate the fields

surrounding the Craw Stane.

James Ellis: Surrounding the Craw Stane

are two circular ditches,

the inner one, about 100 feet in diameter,

and the outer one, 160 feet.

Then, surrounding these two ditches is a slight rise

in the earth, also circular in shape,

which measures about 200 feet across.

The outermost feature is probably some sort of

protective wall, like a palisade.

Dr. Leonard: The thing is, these circular earthworks

aren't entirely closed off.

They each have a gap which lines up with the gap in the next.

And the Craw Stane is positioned right next to the opening

of the innermost ditch.

So it was likely a marker of sorts, right at the entranceway

into the heart of these fortifications.

Dr. Riskin: Inside the innermost feature is a series

of circular holes that line up to form this rectangle

that's about 30 by 16 feet.

And there's another one of those similar things

right at the entrance.

So it looks like these are the remains of structures,

maybe houses, and pretty big ones at that.

Narrator: Just outside the palisade,

the archaeologists excavate the remains

of charcoal and charred timbers.

These are radiocarbon dated to the same time period

as the fortification of Tap O'Noth,

the 4th to 6th century CE.

Anthea Nardi: Similarly to what the occupation layers

at Tap O'Noth revealed, there are also shards

from Roman amphorae as well as small pieces of curbed glassware

that we think are old drinking vessels.

The glass would have been imported from France

and the amphorae from the eastern Mediterranean.

James Ellis: All in all, more than 1,000 artifacts

have been pulled out of the ground

at the Craw Stane Complex.

And they all point to some surprisingly well connected

and well-off Picts.

The remains of these luxury artifacts indicate

that Tap O'Noth was by no means an outlier,

but part of a fairly large Pictish Kingdom

that had its seat of power at Rhynie.

Dr. Leonard: So previously, we thought that the Picts

were a rather loose assembly of warring groups,

not very well connected with one other,

not very well connected with the rest of the world.

But all these artefacts prove how wrong we were.

But if they were as organised as we now think,

do we have any evidence of how they managed to project

this power, and use it to their advantage?

Narrator: Writing in the 4th century,

the Roman historian Ammianus Marcellinus described an event

he called the Barbarian Conspiracy,

where Roman Britain was attacked

by various barbarian tribes,

the Picts among them.

Dr. Riskin: According to Ammianus, this coalition

of barbarians attacked Roman positions from the sea

and from the land, at the same time,

destroying the forces that were loyal to the empire,

and seizing control of a large amount of territory.

To pull off a stunt like that you need serious coordination,

not to mention lots of soldiers and lots of materials.

Narrator: Curious about where the Picts could have launched

these coordinated raids from,

the archaeologists follow their instinct to the sea,

where at a site named Dunnicaer,

20 miles south of Aberdeen,

several Pictish stones have been discovered.

Anthea Nardi: Dunnicaer is a sea stack rising up out of the sea

that measures only 65 by 40 feet.

Doing anything at Dunnicaer isn't exactly easy.

In order to navigate it,

And even if and when you do arrive,

you have very little room to manoeuvre.

One wrong step and you're done for.

Consistent with their other finds at Tap O'Noth

and Craw Stane, archaeologists' excavations reveal

the remains of houses made of timber,

all of them containing a central hearth.

They also find clay shards

that are impressed with a range of different designs.

James Ellis: The clay has an interesting appearance:

it is red or black and has a glossy finish,

with some pieces having more of a soft lustre,

while others shine brightly in the light.

Dr. Leonard: This is what we call Samian ware!

And although it was produced in eastern France,

it is known to have been used by Romans all over Britain.

It is high quality and would have been worth a fair amount.

So like we see with the artefacts found at Tap O'Noth

and Craw Stane, it appears several Pictish communities

had access to significant wealth and extensive trade networks.

Dr. Riskin: Maps of this place from the 19th century

show two pillars rising up out of the sea,

whereas now there's only one.

So most people believe that if you go back 1,500 years or so,

this was all part of the mainland.

It would have been far more formidable and extensive

than what we can see today, and so what we think is

that the Picts assembled their armies in places like this,

places like Tap O'Noth and sent them out by sea

and by land to attack the Romans.

Narrator: Even for the mighty Roman Empire,

the Picts proved a formidable foe.

They remained an unconquered thorn in the Romans' side

for the entirety of their occupation of Britain

until they finally withdrew from the island in 410 CE.

Anthea Nardi: It's uncertain what became of the Picts,

but there is nothing like a common enemy to unite people.

And when the Vikings showed up on Britain's shores

a few hundred years later,

chances are, the Picts united with other tribes

to fight off the new invader,

and over time, assimilated into them.

Narrator: Around the early 10th century, the Picts disappeared

from the historical record, a misunderstood people

who were far more sophisticated

than history has given them credit for.

After all, giving the mighty Romans a run for their money

is no small feat.

♪♪

Narrator: On the rugged Northwest coast of Iceland

lies The Westfjords,

known as one of the country's most spectacular

and awe-inspiring regions,

not to mention...remote.

Dr. Cantor: With only three hours of sunlight in the winter,

the Westfjords have a tundra climate,

which means that the winters are long,

dark, and freezing cold.

The temperatures are so frigid

that there is a permanent layer of frozen ground

beneath the surface, called permafrost.

Dr. Agbedor: The coastline is heavily indented

by dozens of Fjords created by ancient glaciers.

And the lack of flat lowlands limits agriculture.

This makes the Westfjords very sparsely populated

with just over 7,000 inhabitants

spread out over the region's 8,600 square mile area.

That's less than one person per square mile.

Anthea Nardi: Because the area is so underpopulated,

wildlife here flourishes.

You'll find creatures like seals, whales, dolphins

and plenty of different types of birds like the very cute puffin.

Now at the top of the food chain is the Arctic Fox.

Narrator: A group of scientists are conducting research

in the Westfjords, when they discover something startling

while analysing the remains of an Arctic Fox.

Dr. Riskin: It's got purple bones!

Specifically, it's the mandibles or jaw bones.

That is super weird!

What could possibly make bone turn colour?

I mean, you can see the teeth aren't affected.

So what's going on here?

Narrator: Descendants of the last Ice Age,

the Arctic Fox came to Iceland by walking over frozen

sea bridges and thrived in this unforgiving climate

for over ten thousand years.

Dr. Cantor: The Arctic Fox is Iceland's

only native land mammal.

It's an apex predator that has flourished,

since before the Vikings settled here,

Arctic foxes battle the elements and outsmart predators

as well as those who hunt them for their fur,

as part of Icelandic culture.

Dr. Agbedor: The relationship between the Arctic Fox

and humans has been difficult.

For years, farmers killed them to protect their livestock.

And in the last decade alone,

more than 56,000 foxes have been destroyed

at the request of the government,

to help protect the farm animals of the country.

Municipalities are obligated to pay fox hunters

for each fox they catch.

In 2020, the cost was almost 134 million Icelandic Krona.

Narrator: Due to the excessive hunting of the species,

Arctic Fox remains are easy to find in the Westfjords,

which is convenient for wildlife researchers.

Dr. Riskin: The purple bones phenomenon was first observed

in 2007, then it went away,

and it wasn't seen again for about five years, in 2013.

Then after that, it seems to come up every year

for the next five years or so.

Really weird pattern,

and scientists have absolutely no idea

what's causing this discolouration.

Anthea Nardi: The first thing that pops into your head

is that maybe it's related to evolution.

These animals have already adapted to a lot

over the past few centuries.

Unlike other animals in the region,

the Arctic Fox does not hibernate through the winter,

but instead adapts to the changing weather.

Dr. Riskin: Arctic foxes are perfectly adapted

to these northern climates.

They have a coat that's comprised of multiple layers

of fur, which is perfect for heat insulation.

They have the ability to pack on

50 percent extra body fat right before the winter,

which helps them get through that difficult season.

And they have this countercurrent heat exchange

in their paws, that lets them keep their body warm

while their feet are walking on the really cold ice.

It's no wonder these animals have conquered

the northern part of this planet.

They're in Canada, they're in Greenland,

they're in Russia, they're in Norway,

you name it. And yet,

it's only here in Iceland,

in this one part of Iceland,

that they have these purple jaws.

So what is going on there?

Dr. Cantor: Interestingly, the Arctic Fox's coat

is usually brown in summer and white in winter.

It changes colour to match its environment.

So maybe this is connected to the

discoloration of their bones.

Narrator: Some wildlife ecologists hypothesise

that exposure to contaminants,

such as persistent organic pollutants

can alter bones' shape in a single lifespan,

and perhaps even their colour.

Dr. Riskin: Persistent organic pollutants are toxic chemicals

that are bad for human health and for animal health.

And if you've ever hear of the pesticide DDT,

its a perfect example of one.

The thing that makes those so dangerous,

is that they bioaccumulate.

So one animal eats some, it goes into their body.

Then when a predator eats that animal,

it gets all of those pollutants,

and because predators eat lots of individuals,

they get pollutants every single time and they accumulate.

So is that what explains the purple jaw?

Dr. Cantor: The Arctic Fox is known as an indicator species.

These are plants and animals

that serve as a focal point, for researchers to understand

the effects of pollution and climate change

on specific ecosystems.

This is because, as apex predators,

they are more sensitive to changes in the environment

than other animals.

So could the change in colour in the foxes' bones

have been caused by the environment?

Dr. Agbedor: It could be a pollutant in the water.

The foxes in the Westfjords are known to rely

heavily on food from the ocean.

Narrator: While environmental issues in the region seem like

a very plausible reason for the discoloration

of the Arctic Foxes' bones,

some observers believe it could be something else.

Anthea Nardi: Chlamydomonas nivalis is a single-celled

organism that is found in glacial ice and soil

around the world.

But, in very high concentrations it has the power

to turn glacial ice pink,

giving it the name, 'watermelon snow.'

Dr. Riskin: Iceland's northernmost ice cap,

Drangaj ökull is the only glacier in the Westfjords,

and it just happens to have that algae on it.

It has watermelon snow.

So that might be finding its way into the food chain there

and then into the bones of the Arctic Foxes.

Narrator: Thousands of miles away from Iceland,

along the coasts of the Pacific Ocean in North America,

another animal has been found to have

purple bones. The Sea Otter.

Anthea Nardi: Some sea otters develop purple teeth and bones

from a steady diet of sea urchins,

which have a reddish pigment called echinochrome

in their shells and spines.

Dr. Cantor: This phenomenon can also happen to humans

who eat too many carrots,

which contain pigments called carotenoids.

When this pigment accumulates in your body,

your skin can turn a yellow-orange shade.

So could the discolouration of the fox bones in Iceland,

be due to the foxes diet?

Narrator: An apex predator,

the Arctic foxes in the Westfjords

eat whatever they can find,

but their diet mainly consists of birds, eggs, mice,

and sea life, specifically mussels.

Dr. Agbedor: The Blue mussel and the Horse mussel

are commonly found in shallow waters and tide pools

off Westfjord's shores.

So they are easily accessible to the Arctic Fox.

The purple colour of these mussels' shells

might stain the bones of predators that eat them,

like the echinochrome staining found in sea otters.

Dr. Riskin: It's also possible that because

they're filter feeders,

the mussels could be accumulating

various pollutants and chemicals from the seawater,

or they could be accumulating the pigments

from that watermelon snow

that's made by Chlamydomonas nivalis algae in the glaciers,

and then passing all of that up the food chain to those foxes.

Narrator: The Secret of the purple fox bones

discovered in the Westfjords,

could have been caused by any of these factors.

Or a combination of all or some of them.

The mystery lives on.

♪♪

Narrator: 23 Miles Northwest of Stockholm, Sweden,

on the icy shores of Lake Malaren

sits the ancient town of Sigtuna.

Dr. Cantor: Founded by Erik the Victorious in 980 CE,

Sigtuna is Sweden's oldest town and steeped in history.

For roughly 250 years,

it was a powerful political and cultural centre

and considered one of the country's most important cities.

Dr. Agbedor: Nowadays, it's kind of small

with a population of just under 10,000,

and its importance has diminished.

Still, it remains a culturally

and historically significant place,

with ancient homes, mediaeval churches,

and even Viking rune stones dotting the area.

Dr. Leonard: The winters here are quite harsh,

with very little daylight

and average temperatures below freezing.

This cold, icy environment is ideal for preserving the past,

and given the town's rich history,

it's an archaeological hotspot.

♪♪

Narrator: In a remote part of town, a team of engineers

prepare for an upcoming construction project,

when they find something they were not expecting.

Dr. Agbedor: As they dig among the clay and earth,

they discover a series of large stones

positioned in a rectangle,

all different shapes and sizes.

It's definitely not a natural formation.

Someone put these rocks here for a reason.

So what is it?

Dr. Leonard: It could be the remains of an old structure,

but it's too small to be a house,

so it might be what's left of a stone kiln.

Kilns have been essential for thousands of years,

they were used to fire clay objects

to make pottery, bricks and tiles.

Dr. Cantor: They were essentially large ovens

with pits dug into the earth,

where wood or charcoal would be placed,

to provide the intense heat necessary

to harden molded clay bricks.

Dr. Agbedor: The ruins of several ancient kilns

have been discovered in Sweden.

One of them, only about 30 miles away

from Sigtuna in Saltsj ö-Boo.

James Ellis: But if it was a kiln,

there would be evidence of fire.

Such as ash, the burnt remains of charcoal and wood,

yet none was found.

Also, there aren't enough stones, the ruins of a kiln

would be much more substantial than that.

Narrator: Archaeologists are brought in to excavate the area.

And as they do they make a startling discovery.

James Ellis: Beneath the rock formation,

they find seven well-preserved tombs

with intact skeletons inside,

including four adults and four infants,

all buried flat on their backs in an East-West orientation.

The stones positioned in the rectangle,

are what's called a cist,

which is basically a stone-lined grave.

Also, a man-made pile of different-sized stones and rocks

known as a 'cairn' was found on top of four of the tombs.

So, who were these people and why are they buried together?

Narrator: Excavating further, the archaeologists

are surprised to discover that one of the tombs

has two very small bodies placed close together.

James Ellis: We know that Sigtuna was founded in 980

and was an important city for around 250 years.

This would've been during the reign of the Vikings.

And according to some historical accounts,

they were known to practise human sacrifice.

Narrator: In 1934, a Viking fortress

on the Danish Island of Zealand was excavated.

And while most of the artefacts unearthed

were mundane objects like pottery, needles,

scissors and weaving instruments,

something sinister was also discovered.

Dr. Cantor: Archaeologists found an area

that is believed to have served as a sacrificial site

before the fortress was fully constructed in the early 980s,

around the time that Sigtuna was founded.

Human and animal bones were found,

and most of the human remains were of children

between the ages of 4 and 7.

And there was evidence that they were sacrificed.

So it's possible that the skeletons of Sigtuna

were also sacrificed, including the four children.

Dr. Leonard: However, the bones at the fortress

were found piled together in a large pit.

It's believed that these pits had important symbolic meaning

related to Norse mythology, where Odin gained his wisdom

from drinking at Mimir's well.

The remains at Sigtuna were given proper burials,

not disposed of in this manner.

Also, the Sigtuna skeletons are complete

and show no signs of trauma.

So it's unlikely that they were the victims of human sacrifice.

Narrator: Continuing to investigate the site at Sigtuna

the team comes across several curious items

alongside the remains.

Dr. Cantor: They found what looks like a leather belt

with iron and silver-gilt copper alloy fittings.

And also an ornate bone comb,

all of which was prized by Scandinavians at that time.

Dr. Agbedor: Grooming was an important part

of Viking culture, and their toiletry kits

were not too different from ours today,

with beautiful patterned combs, ear picks and tweezers...

And they were carved from deer antlers

or bones from animals like whales.

Narrator: As the archaeologists continue

to examine the remains,

they discover something in the mouth

of one of the adult skeletons.

James Ellis: Silver coins!

This is a practice that was used throughout history

going back as far as the Egyptians,

where Pharaohs were buried with their riches

so they would have everything they needed in the afterlife.

Dr. Agbedor: The ancient Greeks believed

that the dead needed to pay or bribe the boatman Charon,

to ferry them across the River Styx into the afterlife.

And if they couldn't pay,

they would have to wait for 100 years

until eternal rest.

A coin called Charon's Obol was placed in the person's mouth

or with the body at burial,

for the voyage and as a seal

to protect the person's soul to keep it from returning.

Dr. Cantor: The Romans also adopted this burial practice

and the custom spread throughout the Roman Empire

and to different parts of Europe

where Christianity was practised.

So why are we finding it at a Viking burial site?

Narrator: As the search for answers

on this unique burial continues,

another startling discovery complicates matters.

Dr. Cantor: Deposits of charcoal and in some cases

partially burnt caskets were found.

Suggesting that fire rituals,

which were common in Viking society

were involved in at least four of the burials.

Cremation in particular was common

among the earliest Vikings,

who believed the smoke would help carry the departed

into the afterlife.

Dr. Agbedor: This is very interesting.

On the one hand, you've got evidence

of Christian burial practices like the stone cairns

and the coins in the mouth,

and on the other, obvious Viking rituals

and artefacts, like the comb.

Narrator: Carbon dating indicates

that the remains are from the 900s,

meaning these tombs were built around the same time

that Sigtuna was founded,

an important era in Swedish history.

Dr. Leonard: As the Vikings ravaged their way

through Europe, they began to bring something else home

with them besides the spoils of war.

A new religion called Christianity.

And before long, Vikings who worshipped Norse Gods

such as Odin and Thor,

were living side-by-side with those

who considered Jesus Christ their Lord and Saviour.

Dr. Abgedor: The area of Sigtuna was traditionally known

as a Viking stronghold.

But would later become an important centre

for Christianity.

So it's feasible that these individuals

were among the earliest Christians in Sweden

and were living in an age,

where there was a move away from Viking beliefs,

towards organised religion.

Narrator: As the archaeologists examine the two infant bodies

entombed together,

they find that the twins were most likely

the tragic result of a late miscarriage or stillbirth.

Dr. Agbedor: It's very possible that this family suffered

a huge loss and found Christianity in that moment

when they were looking for hope or meaning.

James Ellis: During transitional times like this,

when traditional structures might be in flux,

or new influences were introduced,

families might selectively adopt practices

from different cultural traditions

or modify existing ones to cope with tragedies.

Narrator: The burial site at Sigtuna tells the story

of the complex shifting ideologies in a country

that was forever changed by religion,

marking a pivotal point in the cultural transformation

of Sweden and the Vikings.

♪♪