All language subtitles for Secrets in the Ice S02E06 Siberias Frozen Necropolis 1080p WEB h264-KOMPOST_track3_[eng]

[announcer speaking]

[narrator] A mummified
Siberian body

is found encased in a
mysterious burial shroud.

When you come across
something this unique,

so many questions start
racing through your mind.

[Dr. Cantor] A find
like this is quite rare.

This place is very remote.

[narrator] Could a
turn-of-the-century

Antarctic camp
found floating on an iceberg

lead researchers to a lost
one-of-a-kind polar vehicle?

How could it have gotten onto one of
these giant icebergs in the first place?

[narrator] An ominous dark hole
suddenly appears on a glacier

on Mount St. Helens.

Researchers think it looks like

what could be an entrance
to a monster's lair.

This is a potentially
lethal environment.

[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.

Northern Siberia,

its very name evokes some
of the world's toughest people

battling winter's
harshest wrath.

Northern Siberia, is legendary
for its intense winters

and remote inaccessible areas.

At certain times of year,

villages can be
completely disconnected

from one another.

[narrator] In 2015, researchers
make a grim discovery

at a place known as Zeleny Yar.

They uncover
an unusual-looking burial site

in the frozen ground.

Inside, they find a body wrapped
in what appears to be tree bark.

When you come across
something this unique,

so many questions start
racing through your mind.

Who is this person?

Why are they wrapped
in a shroud?

[Dr. Cantor] A find like this
is quite rare.

We're talking about Siberia.

This place is very remote.

[Marina] Finding a body
like this is pretty unusual.

Why would someone wrap
a body in bark?

[narrator] To get some answers,

they transport the body
to a lab for testing.

[Alison] When we find a body
wrapped in something,

we recognize that there's
a certain amount of care

that was given to the
preparation of the body.

There was a certain amount of respect
that was being paid to this individual.

[narrator] The size
of the shroud

leads them to believe
it could be a teenager.

When researchers
delicately cut open the shroud,

they discover a hidden layer
of reindeer fur.

Could this bark cloth
and reindeer fur hint

at some special burial ritual?

[narrator] Below the fur, they
make another strange discovery.

Carefully placed upon the
body, covering the face, chest,

abdomen, and groin are
four large flat pieces of copper.

This burial custom has never
been found in graves in Siberia.

[narrator] Removing the
copper pieces from the face,

they realize
it's not a teenager,

but the eerie mummified body
of a young boy.

[Alison] It's astonishing

to look into
the perfectly preserved face

of one that was so young.

[narrator] The boy died when
he was only seven years old,

around the year 1250,

during the medieval period.

But as researchers continue
their excavation,

they make
an astounding discovery.

They find 88 separate hidden
graves in the frozen ground,

all buried between
the 8th and 13th centuries.

[Alison] It's actually
pretty amazing,

this boy's grave was
part of a hole in Acropolis.

But without
any distinctive artifacts,

we still don't know
who these people were.

[narrator] As researchers
uncover the bodies,

another strange anomaly
comes to light.

Out of the 88 corpses,

they only find one adult female.

[Morgan] It's hard to
understand just why

they didn't bury their women
in the same grave site.

This discovery
is really strange.

Maybe they had a completely
different ritual for burying the women.

[Marina] In some cultures,
soldiers are buried separately

from the rest of the population.

So, it's possible
that there were no women

in this burial simply because they
were separated from the soldiers.

[narrator] Some of the other bodies
are also buried with copper plates

and some are
partially mummified.

But out of the 88 bodies found,

the boy in the birch bark shroud

is in the most advanced state
of mummification.

Beneath his body, still
wrapped inside the bark shroud,

researchers discover an axe,
a knife, and multiple rings.

Certainly, he could have worn
the rings

and he could have used the knife
and used the axe in his daily life.

Some have suggested that the
copper plates found on his body

might have been some
kind of rudimentary armor.

The copper pieces might
also be symbolic of armor,

but as a metal, it's far too
soft to offer much protection.

If he were a young warrior,

the copper plating would have
been no match for an iron sword.

If he suffered
a traumatic death,

you might expect to find
evidence of injuries

like broken bones
or lacerations on the skin.

But in fact,
there are no puncture wounds,

there's no evidence of
slashing anywhere on the body.

[narrator] Ancient
mummification techniques

remove key organs from the body.

But CT scans of the boy
reveal his brain

and internal organs
are still intact.

In some cultures,
only their leader mummified.

Like the famous mummies
found in Egypt.

Even if he wasn't
a young warrior,

he was clearly someone
of high status.

[narrator] If he and many
of the other bodies

weren't mummified on purpose,

how could it have occurred?

Copper has
antimicrobial properties.

Which means that bacteria have a really
tough time surviving on that surface.

The copper plates
may have slowed the decay

in the areas they were placed.

[Dr. Cantor] Plus, the boy
was buried in tundra conditions

where snow covers the ground
ten months of the year.

The cold temperatures
also slow down decay.

[Alison] In extreme
environments,

like high altitudes
and polar regions,

it's possible to find bodies that
have been accidentally mummified.

This is why scientists
call it accidental

or natural mummification.

But they still don't understand

why they buried their dead
this way

and why in this location.

Whoever they were, they must
at some point have lived close by,

if their dead are buried there.

[narrator] Could the nearest
town of Salekhard, 20 miles away,

hold clues to the lost identity
of the 88 Siberian graves?

[Marina] The town wasn't
established until the 16th century.

So these bodies predate
the town by hundreds of years.

[Alison] This is a huge necropolis
that has attracted burials for centuries,

and yet archaeologists
haven't found any evidence

of a contemporary
settlement nearby.

[narrator] The Yamal peninsula
has been home to the Nenets

and Khanty people for centuries.

They've migrated
and herded reindeer

through this northern tundra
for generations.

The Nenets are a nomadic people,

and so archaeologists wonder
whether the boy

might still be
a distant ancestor.

[narrator] When researchers compare
the boy's DNA to the Nenets people,

they discover
a genetic connection.

But strangely,

the Nenets don't have
an oral history

of the massive Zeleny Yar
burial site.

Could a rare burial practice
of the local Nenets people

reveal a hidden connection
to the ancient acropolis?

[narrator] In remote Siberia,

an Aryan acropolis is found containing
88 unmarked medieval graves.

Experts believe
they are distant ancestors

of the indigenous Nenets people.

But the Nenets have no
knowledge of the vast grave site.

Perhaps there are
cultural similarities

that could shed light
on why they were buried here.

The memory of who these
people were has disappeared.

But maybe some of their
traditions have endured.

In Nenet culture,
when someone dies,

there is a tradition
to punch a hole

through the bottom
of a metal pot or bucket.

The idea is that
the cauldron itself is broken,

it can no longer be used
in this world.

But it will be intact and whole,
ready for use in the afterlife.

So it is possible that the pieces
of copper found on these bodies

are just another example
of that tradition.

[narrator] But if the people buried here
do have relations to the Nenets community,

researchers still wonder,

what is the significance
of this place?

Zeleny Yar, the area where
the necropolis was found,

is situated by a river
on a floodplain island

and it's the highest point in
the area from miles around.

This location
is where two rivers meet

and the higher ground would
have been less prone to flooding.

[Alison] It's really interesting
that all of the bodies

are positioned facing the river.

Usually, when you find
a group of bodies

arranged according to some
geographical feature, like a river,

it indicates that there's some
significance there.

Like, maybe this river
is sacred.

In many cultures, rivers and bodies
of water holds special significance.

And in fact, there are lots
of myths and legends around

crossing rivers
into the afterlife.

[narrator] But with no written
records, the mummified boy,

his incredible grave goods,
and the 88 other graves

are all that's left to bear silent
witness to a mysterious people.

We don't know
what happened to these people,

but the preservation of this boy is
giving him a second life in our world.

[narrator] Antarctica,

one of the most brutally cold
places in the world.

A frozen desert where no life
exists except for at its melting edges.

On its southern side

sits a deep bay
known as the Ross Sea.

It's here that America's
McMurdo Station

has become a hub of
international polar exploration.

It's a bleak
and inhospitable place.

Blizzards and katabatic winds can
blow in from nowhere and last for days.

[narrator] In 1963,

a looker on the American
icebreaker USS Edisto

spots a stadium-sized iceberg
in the Ross Sea

and signals for the ship
to stop.

The Ross Sea, it's a graveyard

for these enormous icebergs that
carve off the front of the Ross Ice Shelf.

It happens all the time there.

[narrator] The cliffs
of the iceberg

are an incredible
nine storeys high.

But about halfway up,

there's a strange dark smear
visible in the pristine ice.

As the ship gets closer,

it looks like debris
stuck in the iceberg.

But what is it?

[Amma] In Antarctica,

planes go missing
at an alarming rate.

So maybe these are the remains

of a plane that crashed
into the side of an iceberg.

[narrator] To see better,
the captain creeps the Edisto

as close to the iceberg
as he dares.

Suddenly,

a dark shadow snaps into focus.

Huge boards of wood
and large pieces of canvas

are sticking out
of the iceberg's face.

The crew of the Edisto marvel
at this strange sight.

Could these materials be from a lost
camp once used by Antarctic explorers?

In the early 1900s,

adventurers were obsessed
with discovering the South Pole.

Famous Antarctic pioneers like
Robert. F. Scott, Ernest Shackleton,

and Admiral Richard Byrd all
built camps on the continent.

If it is one of these famous
explorers camps,

how could it have gotten onto one of
these giant icebergs in the first place?

[narrator] The helicopter
is ready,

it flies over the iceberg
for a better look.

The flopping sections of canvas
appear to be large pieces of tarpaulin.

The wooden boards look
like the interior walls of a hut.

What is the tarpaulin covering?

Could it be the roof of some
kind of makeshift structure?

[narrator] When the helicopter
lands on the surface of the iceberg,

the crew are stunned.

[Amma] Four thick poles
are jutting out of the ice.

They look like telephone poles.

[narrator] The presence
of these poles

clearly indicate that this
was some kind of camp.

But do these poles provide
enough of a clue

to figure out whose camp it is?

[narrator] In 1940, just three
miles into the Ross Ice Shelf,

an American crew is building
Rear Admiral Richard E. Byrd's

third Antarctic base,

Little America III.

By then, Byrd had completed
two successful trips to Antarctica.

He was well on his way to being
considered a legendary explorer.

He was the first person
to fly across the South Pole.

[narrator]
Little America III

was bigger than
his first two camps.

With room for more equipment

and a powerful radio
broadcasting station

that required several large
telephone poles...

- [telephone ringing]
- for transmission.

Are these large poles sticking out of
the iceberg evidence of Byrd's old camp?

Well, they could be,

but they have to be
completely sure.

There is one smoking gun
piece of evidence that, if found,

would confirm
that this was Byrd's camp.

[narrator]
Byrd arrived in Antarctica

with what at the time
was the most advanced piece

of equipment ever built
for polar exploration.

He called it
the Antarctic Snow Cruiser.

Part ice tank, part ice bus,

part invincible travel lodge.

[Mike] It was last seen partially
buried on the Ross Ice Shelf.

If they can find that,

they'll have found a monumental
relic of polar exploration.

[Amma] It was supposed to
have a range of 5,000 miles.

Byrd wanted a five-person crew to
be able to explore Antarctica for days

without ever having to leave
the vehicle.

[narrator] The Snow Cruiser
was 56 feet long,

19 feet wide, and 16 feet tall.

Smooth ten-foot-tall balloon
tires were custom-built

to handle Antarctica's
choppy ice and wide crevasses.

A pair of six-cylinder
diesel engines

powered four diesel electric
drive trains,

generating an intimidating
four-wheel-drive machine.

They ran a combined
300 horsepower

and a maximum speed of 30 mph.

Fully loaded,

the Snow Cruiser weighed
37 tonnes.

And on the inside,

there were sleeping quarters,

a workshop,

a galley,

plenty of storage space,

and even a dark room.

But that's not all.

Byrd wanted room on top

to carry a small plane

that would fly ahead

and scout safe routes

for the Snow Cruiser.

[narrator] The Snow Cruiser
cost $150,000

almost $3 million today.

The price and the innovation
of the design

propelled the Snow Cruiser
to instant fame.

[narrator] But as the
Snow Cruiser arrives

with Byrd standing
victorious on top,

the makeshift gangway breaks.

[narrator] The destroyed camp of famous
Antarctic explorer Admiral Richard Byrd

may have been seen by
the crew of the USS Edisto

on an iceberg floating
in the Ross Sea.

But where is his innovative polar
vehicle called the Snow Cruiser?

After narrowly escaping
a crash upon arrival,

the Snow Cruiser struggles
to live up to its reputation.

This thing weighed 37 tonnes.
If it went down,

it's staying down.

[Amma] Things went from bad
to worse.

Byrd learned the hard way
that smooth wheels

provide near-zero traction
on ice and snow.

[narrator] A research team
managed to complete

a 92-mile journey
soon after arrival.

But the smooth treadless
tires frequently slipped

and sank the giant vehicle
deep into the snow.

[Mike] The crew added chains to
try and get better grip on the tires.

They found they got the
best traction going backwards.

So, they did the whole thing
in reverse.

[Dr. Cantor] The Snow Cruiser
barely made it back to base camp

and it never drove more
than 100 miles.

His massive Antarctic
exploration machine was a bust.

It's thought that Byrd would have
parked it near the main building

and it would have been used
as extra storage or living quarters.

[narrator] If experts can establish
where Byrd parked the Snow Cruiser,

it could help them determine
if the debris in the iceberg

is in fact Byrd's camp.

The helicopter crew from the
Edisto are not equipped to dig down

through 20-plus feet of ice to
further investigate the camp.

[Dr. Cantor] So the helicopter crew,
they just stood there on this iceberg.

They didn't really know
what to do.

[Morgan] Have they found
the entire camp,

did only part of the camp
breakaway?

And where is the Snow Cruiser?

They have no idea.

And the iceberg is too unstable

to safely repel down
to the building.

[narrator] The captain of the
Edisto makes a tough decision,

he calls the helicopter
back to the ship.

The helicopter pilot told them
he thought it was Little America III,

but that doesn't solve the
second part of our mystery.

Was the Snow Cruiser
hidden in there too?

The crew watched the iceberg
and the camp with it

float away toward the horizon.

[narrator] But in 2005,
two American researchers

decide to take another look
at the lingering mystery.

The researchers first analyze
satellite imagery

of the Ross Ice Shelf
from 1957 to 1962,

the years the iceberg was most
likely to have calved into the ocean.

Ice shelves are
like fingernails,

they grow from the back, but
then break off on the front edge.

It could take years,
sometimes even decades

for a section of ice shelf
to become an iceberg.

[Dr. Cantor]
What they discovered

is that Byrd's camp would
have been pushed

to the edge of the ice shelf.

Perfect location
to calve off into an iceberg.

[narrator] They calculate
that an iceberg calved

without anyone noticing
sometime between 1957 and 1962.

Then after working its way
300 miles across the Ross Sea,

it was on course
to meet the Edisto.

Either the Snow Cruiser plunged into
the water when the iceberg broke off

or it's still on the far side of
the visible hut encased in ice.

It is a mystery to this day where
that Snow Cruiser has gone.

[narrator] The researchers closely examine
photographs and maps of Byrd's camp,

looking for any evidence
of the Snow Cruiser.

Based on the position
of the main huts,

the air hangar and the large
telegraph poles,

they conclude the Snow Cruiser
likely fell into the ocean sometime

before the rest of the camp
was sighted on the iceberg.

This spot is where
some researchers think

is the most probable location
for the Snow Cruiser,

but it's covered
by the Ross Ice Shelf.

The good news is that the
water underneath the ice shelf

is anywhere from
1,000 to 3,000 feet deep.

So a search mission
is technically possible.

Maybe one day someone
will find it down there

and we'll finally get
another look

at this legendary piece
of polar technology.

[narrator] Until it's located
on the ocean floor,

the Antarctic Snow Cruiser's
final resting place

remains a secret buried
in the icy depths.

[narrator] 50 miles
northeast of Portland, Oregon,

on the western edge
of the Cascade mountains

rises the icy peak
of Mount St. Helens.

The highest peaks
of the Cascades

are steeply-sloped
active volcanoes.

The terrain here is rugged.

It's not for the faint of heart.

At 8,300 feet,
Mount St. Helens

is covered with snow
year around.

And around the lava cone is a
young glacier rapidly growing.

How can a glacier
that's rapidly growing

exist over the top
of an active volcano?

[narrator] In 2012,

scientists conducting an aerial
survey over Mount St. Helens

discover an odd-looking feature.

As they approach the glacier
that sits on top of the mountain,

they see an ominous-looking
black object in the ice.

[narrator] As the scientists
get closer,

they realize
that it's a massive hole

60 feet wide.

Researchers think it looks like

what could be an entrance
to a monster's lair.

So they dub it
The Godzilla Hole.

[Morgan] What is this thing?

How and why did this hole form?

[narrator] Mount St. Helens is the
site of the deadliest volcanic eruption

in US history.

In 1980, after lying dormant
for over 100 years,

the volcano suddenly erupts,

spewing 540 million tonnes
of ash into the air.

The explosion triggers a
massive landslide, killing 57 people

and decimating everything
within an eight-mile radius.

Could the appearance
of the Godzilla Hole

mean Mount St. Helens
is about to awaken?

The crater of Mount St. Helens
is so dangerous,

it's strictly off-limits
to the public.

Only researchers monitoring
for signs of future eruptions

are allowed anywhere near it.

[Meagan] The interior of Mount St.
Helens' crater is a perilous environment.

It's prone to rock slides,

which sends huge boulders
thundering down crater walls.

Scorching steam is blasting
out of the ground

and this glacier is covered in
deadly crevasses and unstable ice.

[narrator] To find out
what's going on inside,

researchers must descend
into the mysterious hole.

Despite the incredible danger
of entering an active volcano,

they make their way
from base camp

and prepare to descend
into the dark icy cavity.

The hole could be a direct
pathway into a thermal vent.

This is a potentially
lethal environment.

Similar volcanoes
emit poisonous gases

such as carbon dioxide,
hydrogen sulfide,

and sulfur dioxide.

They have to be ready
for anything and everything.

[Meagan] They have to bring
climbing equipment, gas monitors,

self-contained
breathing apparatus,

as well as the necessary
scientific and medical equipment.

[narrator] As scientists ease
over the edge of the hole,

they repel 40 feet
into its dark passage.

Will its icy depths reveal
an impending eruption?

[narrator] A mysterious hole
has appeared

on Mount St. Helens'
rapidly-growing glacier.

Could it be the ominous sign of
another impending catastrophic eruption?

In order to investigate,
a team of researchers

descends into its frozen
depths for the first time.

[water drop]

Humans have never set
foot here before.

It's completely
uncharted territory.

[narrator] What they find at the
bottom is an eerie, cavernous ice cave.

It has 100-foot ceilings and it's
like nothing they've ever seen before.

Tall and narrow, the huge ice
cavern looks strange and otherworldly.

The heat from volcanoes generating
tremendous amounts of steam.

Light trickles in
from the entrance

and illuminates thousands of
these scallops on the cave walls,

these tiny indentations
in the ice.

Beneath the ice is this
vast group of towering caves

that are absolutely
breathtaking.

What earthly forces or dynamics

could have created
something this spectacular?

[narrator] Seismic readings determine
Mount St. Helens is not about to erupt.

These glacial volcanic caves
are extremely rare

and only exist
in a few places in the world.

Unlike rock cave formations,

these caves are constantly shifting
and changing as the glacier grows.

Many glaciers around the world
are retreating,

but this one is actually growing
and expanding up to two feet per day.

This glacier
is only 25 years old,

but parts of it
are over 600 feet thick

and over half a square mile
in area.

[narrator] But is it the heat of
the volcano rising through the ice

that carves out
this giant space?

Maybe the size and shape
of each cave

can give us some clue as to
how these caves were formed.

[narrator] To probe the
mystery of the caves' creation,

the researchers decide
to construct a 3D map.

[Mike] The team uses a Disto laser
to determine the volume of the cave

and map its entire 3D structure.

So much easier
than measuring it all by hand.

[narrator] They discover
a highly unique set of caves.

They're able to map out
over 7,500 feet of passages

and discover ten distinct caves,

some several 100 yards long.

But what forces
could be creating

such an unusual pattern
of tunnels beneath the ice?

[Mike] Normally,
meltwater carves out

these glacial caves
horizontally.

But here we see a vertical
cave with dry, rocky ground.

At any moment,

hot steam can blast
from volcanic vents

underneath the rock
that this glacier sits on.

[Mike] The steam in these events
can get to 140 degrees Fahrenheit.

If the researchers so much as touch the
wrong rock, they could be badly burned.

[narrator] But rising steam
by itself

doesn't account for the eerie
scalloped patterns.

[Alison] It's not quite
that simple.

What could be propelling
the steam?

If you stand in this cave,

you can feel a surprising
amount of air blowing past you.

[narrator] As snowfall above
causes the glacier to grow,

underneath, the caves
are also expanding.

Hot air from the volcanic
vents rises and melts the ice.

The melting cools the air
in the ice cave,

which then interacts
with the outside airflow,

causing it to drop back down,

creating winds within the caves

that sculpt the walls into
strange, mesmerizing formations.

The caves essentially have
their own weather systems.

[narrator] The unique hot and cold
dynamics within Mount St. Helens' caves

are representative of how
weather often behaves on Earth.

But as experts continue
hunting the ice caves

for clues to their
mysterious existence,

they're stunned to discover the
uncanny birth of a brand-new world.

[narrator] Researchers
investigate a giant hole

in a glacier
on Mount St. Helens.

And after discovering a
unique collection of ice caves,

could they pose otherworldly
implications for the future?

They discover that when you have

all these things
coming together,

the heat
and the ice interacting,

something mysterious happens.

[narrator] Researchers find
new signs of life

mushrooms,

moss,

and rare microbes are growing
in the ice caves.

This cave is incredible.

It doesn't just have its own weather
system, it has its own ecosystem.

[Meagan] The newly-formed
caves are filled with volcanic gases.

So how is it possible
for new life to begin forming

in such a hostile
and unstable environment?

As harsh
of an environment as this is,

given how many toxic aspects
are in one place at once,

you wouldn't expect anything
to thrive here.

But life, it finds a way.

So who knows what this place
will evolve into?

It's so new that we're just
beginning to probe its mysteries.

[narrator] If new life
is growing here

inside one of the most paradoxical
environments in the world,

researchers wonder how
long this fragile mystery will last.

Poking out of the harsh Bering
Sea, 300 miles west of Alaska

is a small island known
as St. Paul.

It's part of a remote five-island
chain called the Pribilofs

that are rocky tundra outcrops
in the middle of nowhere.

This place is about the size
of San Francisco

and it gets pounded
by howling winter storms

and huge waves
at the best of times.

[narrator] In 2003,
on St. Paul Island,

a group of American scientists
discover a strange vertical cave.

At the bottom of the cave,
under a rock,

they find what looks like
a long broken dinner roll.

But in reality, it's a well-preserved
ancient mammoth's tooth.

What is a mammoth tooth doing
in a cave, on an island

300 miles off of Alaska?

It's an extraordinary find.

Mammoths could swim,

but they couldn't swim 300
miles across the Bering Sea.

So how did they end up here?

[narrator] Mammoths went
extinct from mainland North America

between 10,000
and 14,000 years ago,

at the end of the last ice age.

Did ancient mammoths
roam this island?

If they did, then this tooth
could change everything

we know about
how they went extinct.

[narrator] The team sends the
tooth for routine carbon dating,

but this is no ordinary tooth.

Scientists are stunned when it
turns out to be only 6,500 years old.

That's an incredible 5,000 years
after the mainland mammoth extinction.

How could this be?

[Dr. Cantor] How did the St. Paul
mammoth survive so much longer

than the other
North American mammoths?

And if they did, what happened
to them, why aren't they still there?

[narrator] 21,000 years ago,

in the middle of the last ice
age, St. Paul is not an island.

Walls of ice over a mile high
cover Alaska and Canada.

And in between those walls are
melted corridors created by hot springs,

volcanoes and micro climates.

St. Paul Island is in
a volcano-ridden area

on the southern end
of the Bering land bridge.

It's a giant stretch of land
connecting Asia to North America.

People walked from the Asian
continent across this land bridge

into North America
and they hunted along the way.

They hunted the saber-toothed
tiger, the short-faced bear,

the giant sloth,

and the woolly mammoth.

[narrator] During the end
of the ice age,

as the human population grows,

the mammoth population
mysteriously shrinks

and almost two thirds of the
larger mammals become extinct.

The most obvious question is, did
humans kill the St. Paul mammoth?

[Morgan] We've all seen those videos
where a bunch of desperate ice age hunters

are throwing spears at a mammoth

and they all celebrate
when they take it down.

But is that really
how the mammoths died?

Overhunting does seem plausible,

but ancient hunters usually
didn't kill more than they needed.

We know humans used mammoths
for food, for clothing, for shelter,

and there is evidence of mammoth
hunting across North America.

[narrator] The local
indigenous tribe called the Aleuts

have had a wide presence in the
Arctic region for thousands of years.

But scientists can find no
evidence on St. Paul Island

that large groups of mammoths
were slaughtered.

Once part of a connected
landmass about 14,000 years ago,

the giant walls of ice began to
melt, causing sea levels to rise.

The ocean swallowed the lowlands
and stranded higher land like St. Paul

into an island
about 6,000 years ago.

[Alison] Is it possible that
mammoths and other animals

living in the area were
trapped by rising sea levels?

It took thousands of years
for sea levels to rise,

so maybe some animals
didn't notice until it was too late.

[narrator] To understand how
the mammoths may have survived,

the scientists focus on something
key to all creatures' survival,

water.

They turn to a lake
known as Lake Hill,

only a quarter-mile away from
the cave where they found the tooth.

This would have been a place
that many animals would have used.

[narrator] Is it possible
that the lake holds a clue

to the secret of the
mammoths' disappearance?

After finding a rare
woolly mammoth tooth

dated to thousands of years after
mainland mammoths went extinct,

researchers believe an
Arctic lake on St. Paul Island

may hold the key to unlocking
a centuries-old mystery.

Scientists return to St. Paul
once the cold has set in

and the lake is frozen

in order to be able to drill

for samples of ancient mud
at the bottom.

Did these mammoths visit
Lake Hill regularly?

[narrator] On a small island
surrounded by saltwater,

scientists believe many
animals would have depended

on the lake for freshwater,
including mammoths.

As they drink, they drop things
like plants they're chewing,

dung, and with it all,
their DNA.

All this falls to the bottom
of the lake, and overtime,

layer upon layer builds up
into a record of what happened.

After four days of drilling,

they gather 150 feet of tubing
containing about 400 pounds of mud.

The lake samples may be their
only hope of finding answers.

[Alison] The next step
is to look for mammal DNA

and they find one
that's unclassified,

one they've never seen before.

[narrator] But how do they figure
out who the DNA belongs to?

[Alison] They compare the DNA
to what would be the mammoths'

closest relative,

African elephants.

And bingo, it's a match!

[narrator] In all core samples dated
between 11,000 to 5,600 years ago,

they find mammoth DNA.

So these mammoths died off
about 5,600 years ago.

It's just incredible that we
can pinpoint this ancient secret,

when the last mammoth roamed
this island to within a century.

[narrator] They now know
when they died,

but can they figure out
how they died?

The island sits very close
to the Ring of Fire,

a massive volcanically active area
stretching from Alaska to South Asia.

Could the mammoths have died from
the fumes of a nearby volcanic eruption?

[narrator] As a volcano
erupts, it spews ash,

cinders and rocks into the air.

The bigger you are,
the bigger your lungs,

and it don't get much bigger
than a mammoth.

If the atmosphere was poisoned,

then the mammoths might
have been the first to go.

[narrator] When they look
at the lake samples,

they don't find
any traces of volcanic ash

during the time of the
mammoths' disappearance.

But they do find a telltale
sign of impending disaster.

Around 7,800 years ago,

the lake starts to transform.

They discover a change in the
population of algae and plugs,

which indicates
the temperature is rising.

The rise in temperature causes
the lake water to evaporate.

Plants can get trampled and
die around the edges of the lake.

When plants and trees disappear,

that also causes
the lake to shrink.

So the lake shrinks
by quite a lot.

This changes the quality of the
water, making it not only shallower,

but murkier and less pure.

[Morgan] The mammoths begin
to lose their main water source,

and they need a lot of it.

They drink up to 50 gallons
a day.

So for a shrinking lake,
like this one,

it probably couldn't keep
supporting that many creatures.

And for the mammoths, they
may have just hit a breaking point.

[narrator] One day,
Lake Hill shrinks

to below the level needed to
support a mammoth population.

The island was a refuge

for one of the last remaining
mammoth populations of North America.

But when their freshwater
source became endangered,

they had nowhere to run.

They were trapped.

[narrator]
The evidence indicates

that the St. Paul mammoths
died of thirst.

Does this mean mammoths
might still exist

if the freshwater lake on St.
Paul Island hadn't dried up?

It's a tantalizing question.