Nova (1974–…): Season 44, Episode 8 - Secrets of the Sky Tombs - full transcript

They came to live
in the highest place on earth.

They buried their dead
even higher.

Check it out.

Check it out.

Littered among the bones

are stunning artifacts.

The part I hate the most
is make a dumb move,

you're done.

Top technical climbers
are needed to reach

the early human remains.

People's heads.



People's heads, yes.

Somehow, the ancient people

adapted to the
Himalayan extremes.

But life wasn't easy.

This might be the cause of death

for this person.

It's hitting right here,
kind of at

the occipital temporal
mastoid junction.

People are people.

There's always conflict
and violence.

Relics are unearthed

from sacred death rituals.

This is how the vampire-killing

firebrand came into being.



Archaeologists are uncovering

the "Secrets of the Sky Tombs,"
up next on NOVA.

NOVA is
prThe Himalayan mountains,

Earth's tallest,
pierce the clouds.

Called "the roof of the world,"

the terrain is so high,
the air so thin,

this was one of the last places
on Earth humans came to inhabit.

Today, about 6,000 people
eke out a living here,

in a region called
Upper Mustang.

Their villages are oases
in a high-altitude desert.

Above several of the villages
are caves

carved by hand long ago.

Many are so hard to reach,
no one has entered them

in recent memory.

But for years, human bones
have tumbled out of the caves...

tantalizing clues that ancient
inhabitants of the Himalaya

are buried here.

Who were these people?

Where did they come from,

and what drove them to populate
such an extreme environment?

An international team
of scientists and climbers

are mounting an expedition
to explore the caves.

Himalayan alpinist Pete Athans
has climbed Mount Everest

seven times.

I've been coming to Nepal now
more than 35 years.

The type of skills
that I bring to the table

is the physical ability
to get into the caves,

getting our scientists into
the caves, more importantly.

Pete has assembled
a team of scientists

and the world's best climbers.

Is that pretty much

above the big portal
as far as you can tell?

He can probably make it in
from there,

but he might
have to swing a little bit.

There are over 10,000 caves
here,

and they've targeted
the most promising.

This one?

You got it!

The climbers are working with
archaeologist

Mark Aldenderfer.

The big question

that we're trying to solve
with this project is,

where did people come from
that began to live here

in these high Himalayas?

What were their origins?

When did they come here?

The task is enormous,
made ever more difficult

by the unforgiving altitude.

The river valley that
runs through Upper Mustang

is one of the only
north-south passages

through the Himalayas in Nepal.

It's an ancient trade route
connecting India to the south

with China's Tibetan Plateau
to the north.

For centuries, Mustang served

as a cultural crossroads

between Tibet
and the Indian subcontinent,

yet managed to keep
its ancient fortresses

and pastoral identity hidden
from foreign visitors

until 1992.

The locals are skillful traders.

Their cash crop is goats.

What defines the people
are their Buddhist beliefs

and a traditional way of life.

Living at such high altitude
is not easy.

Of the five babies born in one
of Upper Mustang's villages

in one year,
only three survived.

Could Mustang's modern people
be the descendants

of those who are buried
in the caves?

Who were the mysterious people,

and why did they carve
these sky tombs?

The team treks
to one of the highest villages

in the region, called Samdzong.

It's just ten kilometers
from the Tibetan border.

To get there, they have to cross
a mountain pass at 14,700 feet.

Pete's children have grown up
in the Himalayas,

coming to Nepal every year
since they were toddlers.

Going up a pretty big pass.

They're at an altitude

where pilots
in unpressurized planes

must breathe
supplemental oxygen.

Curse this.

Low levels of oxygen

can cause debilitating symptoms
in people who don't live here.

The expedition members are
among the first foreigners

in modern times
to visit Samdzong,

which means "earth fortress,"
named after a stronghold

above the village,
now a crumbling ruin.

To show respect
for local traditions,

the expedition holds a puja,

a Buddhist offering
to the mountain deities,

before scouting cliffside caves
in the area.

Pete's son, seven-year-old Finn,
is the first to find

a human bone below some caves.

He shows it to bioarchaelogist
Jacqueline Eng.

Finn found this humerus
of a human.

You can see it's a proximal
humerus on the right.

Don't know what context
this comes from...

maybe washed down
from somewhere.

Caves dot the rock face
above them.

The cliffs have eroded

over time, exposing the contents
of the tombs, which were likely

first accessed by shafts
dug by early people from above.

We've rapped into two chambers

that are connected,
that have lots of what appear

to be human remains,
and animal as well.

As well as more bones
on the outside.

Pete will first map the bones

and artifacts
to provide context.

What we want to do is to

quickly draw, label,
and then number,

and then get them down
to the scientists so they can

start to take a look
at these things and give us

an idea of what
and whom they belong to.

Human remains have been tumbling

out of the cliffside graves
for years.

Because the caves
are swiftly eroding,

this vertical dig
for artifacts and bones

qualifies as rescue archaeology.

There are ten cave tombs in all.

Although he has
a fear of heights,

Mark has to see
the tombs himself

to fully understand the site.

Does it ever get easier?

Uh-uh.

The part I hate the most

is actually walking
up that trail.

It's really narrow, and you just
make a dumb move, you're done.

Pete puts Mark
on a double rappel,

both ropes clipped
into Pete's safety device

so he can stop Mark if he falls.

It's a 200-foot cliff,

with a 40-foot drop
into the uppermost caves.

First, excess dirt
from collapsed walls

is removed from the caves.

Then the dirt is sifted

to uncover the smallest
artifacts.

Each haul bag holds as many as

a hundred bones,
about half an individual.

Mark believes the caves
were carved out intentionally

to entomb the dead.

People carved these caves

because this was
their cultural pattern

on how to deal with the dead.

You know, we Westerners often
put ourselves in cemeteries.

These folks here created a
different kind of cemetery,

what I would call
a communal tomb.

The team finds thousands
of bones.

They'll analyze each one
to piece together the story

of the unknown people.

Now the hard part begins...
doing the lab work.

For Jacqueline Eng,

studying bones is like
reading the personal diaries

of the dead.

I'm always a little bit in awe
when I do get to handle

human remains,

because it's one of
the last stories

that these people can tell...
what they experienced in life.

"I died young,

I had this infection,"
or, "I died peacefully."

Jacqueline determines that
a minimum of 105 individuals

were buried in
the Samdzong cave tombs.

Later, carbon dating

of the remains will show
the people lived between 400

and 650 AD.

But there's something unusual
about how the ancient people

treated their dead.

- Here's a couple of...
- Good God!

That's a cut mark.

Clear cut marks from a knife

are evident
on many of the bones.

In some instances,

multiple cuts
are found in one place.

This is not the distinctive
pattern of cannibalism,

but it indicates
the Samdzong people

were dismembering
and defleshing their dead.

This bears some resemblance

to the local funeral practices
today...

the Buddhist ritual
of sky burial.

When a villager dies here,
they're not buried underground,

but are offered in a high place
to birds of prey

to ensure the deceased
do not return to their bodies.

At the present time,
as soon as somebody dies,

the first thing that the family
will do is to break

that person's back, because
they have a visceral fear

of the dead body

becoming a rolang
which is a term

generally translated as
"zombie."

The idea is that a person dies,
and his or her consciousness

departs from the body,
doesn't realize it's dead,

sees the body there,

and then tries to reinhabit it.

This is one of the reasons,
they say, why they don't

bury the dead,
because they might rise again.

The flesh and even the bones

are cut into small enough pieces
for the vultures to consume.

But unlike the ancient bones
preserved in the caves,

this Buddhist sky burial

is performed to ensure
nothing of the body remains.

Its purpose is to give the dead
a chance of being reincarnated,

to live another life.

Buddhism, with its custom

of sky burials,
is thought to have spread

through this part
of the Himalayas

more than a century

after the Samdzong people
lived and died here.

All right.

Yet, an artifact found in one of

the Samdzong tombs
challenges this notion.

There are some interesting
Buddhist-era remains

in that that we did not expect
whatsoever.

It's like a little
plaque made out of clay.

And it's got a seated Buddha.

A Buddha

in a cave with human bones
seems out of place.

It's a very funny mixture.

They're still doing
the defleshing,

but yet they've got Buddhist
elements with them.

Yeah.

Go figure.

Why does a cave

holding the defleshed bones
of a people predating Buddhism

by more than a century have an
image of the Buddha in it?

Early Buddhism and how it spread
is really a big open question.

Nobody's really found
clear and convincing evidence

of their mortuary patterns.

So these findings
are pretty exciting.

This could be

the earliest Buddhist relic ever
found in the high Himalaya.

Look how fragile.

You have this Buddhist artifact
there,

which seems to be much earlier
than it ould be.

In theory it should be
no older than the 7th century,

but the archaeological evidence
seems to suggest it is older.

So we have Buddhism on the edges
of the Tibetan Plateau

at least quite a long time
before the official introduction

of the religion into the area.

What you also have is evidence

of a type of burial
that precedes the Buddhist

form of burial that took over in
Tibet in the late 8th century.

So the fact that Buddhism
is also present does indicate

that we're at
a transitional stage.

It's possible Buddhism

started earlier here
than previously known,

and people buried the bones
of the dead after removing

the flesh.

The rite perhaps foreshadowed
the sky burial practice

of today.

A forensic investigation
of Samdzong's artifacts

commences, to determine
their possible origins.

One cave had a coffin-like
bed inside.

- Hmm, that's leather.
- That's leather.

Alongside the bed

were the remains of a horse
and some horsetack,

suggesting the body was that
of a prominent individual.

Rich artifacts like
a large copper pot,

bronze bracelets, iron daggers,

and glass beads
littered the grave.

Two mysterious pieces of metal

were also found in the cave.

Wow!

I really don't want to
flatten it too much.

So, that look like a nose?

That kind of looks like an eye.

We have two masks.

They are death masks,

and there's even a third one.

Please don't break!

Here we go.

Check it out.

This guy's got more color.

They need to determine
what metals the masks

are composed of
and where they were made.

So a sample is sent to
University College London

for analysis by metallurgist
Giovanni Massa.

He found there are two layers
of precious metals in the masks.

What you see in this picture

is a section
of one of the masks.

And you can clearly see
there are two different colors...

the front, in yellow color,
which is the gold layer,

and the silver, which is
the back of the mask.

The technique that they used
was hammer welding.

There are no gold and silver

deposits to be found nearby,
and the technology needed

to hammer gold and silver
into death masks

indicates the craftsperson who
created them was highly skilled.

What is actually very striking

is the thinness of the mask...
around 50 microns, which is less

than the thickness
of a human hair.

In fact, to make the artifact,

you won't need
a lot of material.

You would need a sphere

of about this size
for the silver layer

and an even less amount of gold.

Pinholes can be detected

on the outer rim of the mask.

The pinholes were used

to attach the mask
to something else

in order to actually have it
stable on the face

of the person.

I think the mask
was actually sewn onto a fabric

and the glass beads were sewn
onto that fabric as well,

and formed fairly
elaborate headdress.

The mask covered the face,
the fabric covered the head,

and then the glass beads
were covering

that fabric itself,
draped down over the shoulders

onto the chest.

Must've been
absolutely spectacular.

What you see is an incredibly
rich collection of artifacts.

Pretty much any alloy
you could think of.

One of the medallions found
is stylistically

completely different from
the rest of the collection.

You have the copper vessels
that are just hammered surfaces,

very simple.

You have the brass bangles

that have very simple
decorations.

And then you have
this beautiful medallion.

All this shows that these people
were connected to a network.

By the time the Samdzong people
were adorning their dead

with gold masks,
traders from Asia

were exchanging goods
with Europeans

along an ancient trade route to
the north called the Silk Road.

The cave-buried people
might have come

from the vast area we know today
as China.

Or are these simply
trade goods from the north?

They need more evidence.

A single piece of cloth
found in one of the caves

could provide a clue.

Textile expert Margarita Gleba

at University College London

made a discovery using
a scanning electron microscope

that can magnify specimens
up to 30,000 times.

This textile seemed to be made

in what we call plain weave,

or also known as tabby.

Tabby.

And that is the
simplest type of weave

you can create on a loom.

So it's one over, one under.

A curious thing
with this particular sample

is that all the fibers
appear to be parallel

to each other, but they're not
twisted in any way.

Most thread or yarn

is produced by spinning
short fibers, like this wool.

The twisting action

gathers them together
into a single long thread.

The only fiber that allows you
to produce a thread

without a specific twist
is silk.

And the reason for that is that
silk fibers are extremely long.

A single silk fiber,
when unrolled directly

from a silk cocoon, can reach
up to two kilometers in length.

We can be quite sure that we are
dealing with Chinese silk.

Since the cloth

found in the cave is silk,
could this suggest

the people came from China?

The Samdzong remains
only date to 400 AD.

The earliest known pottery
in the region dates back

to 800 BC, so there
must have been people

earlier than Samdzong.

And Mark wants to find them.

Today's archaeological objective
is a cave at 10,000 feet

known as Rhi Rhi.

It's a few hours' journey
from the nearest town.

A complete kitchen, cook staff,
climbing gear, tents, and food

make up the loads

which will have to be carried
across a river

called the Kali Ghandaki.

This is the deepest river gorge

in the world, carved
by the glacial meltwaters

of some of the world's
highest mountains.

Any other time of the year,
the river runs so high here

it's impassable.

With anchors firmly in place,

Pete can rappel down a slope

most climbers
would avoid altogether.

Pete leads another
double rappel with Mark.

Hold on a sec.

Okay, you can just

keep lowering yourself in till
you're seated at the edge.

There you go.

We're good.

It doesn't take long

for them to find
what they're looking for.

These are all human bones
that we're coming up with

at the moment.

A hand-carved wooden peg

is among the first
artifacts found.

It looks like one of those
little daggers.

That's a really cool thing.

What Mark really wants to find

is black pottery
that would suggest the burials

are around 3,000 years old.

This is some good pottery.

Oh, look, yeah, there's
blackware, too, wow.

Very nice.

Thank you, Satish.

The pots are definitely black,

with characteristic
thick handles.

Carbon dating later confirms
the burials are 2,800 years old,

among the earliest ever found
in the Himalayas.

Mark unearths a deep hole
in the cave,

where the early people
were entombed.

What we're looking at is a pit.

And then at some time
they just bring them up here,

open up the pit, and put them
in, and then go back.

They ultimately find the bones
of about five people.

Am I good?
Yep, you're good.

Okay, nice and easy.

Okay, I'm with you.

For the local people,

finding human bones
can be unsettling,

because they believe in
completely eliminating

the remains of a corpse
after death.

Molecular anthropologist
Christina Warinner

notices that the bones
have been disturbed and altered

by visitors to the cave.

A group went in
much, much later,

and they applied ochre
to the remains.

Ochre is this mineral pigment
that's naturally occurring.

This red ochre

has been rubbed
on some of the bones,

and in other cases
sprinkled on them.

We know that it was applied
after death, because we find it

both on the exterior
of the skeletal remains

and also on interior surfaces.

So it must've been applied

after the body
had already decomposed.

It's possible this was done

by Buddhists, long after
the initial burials.

So they didn't just ignore them
or remove them,

but actually actively engaged
with them.

That's very unusual
for this region.

Another find from the cave

supports this theory.

Mixed in with the bones,
and broken into pieces,

was a one-foot-square
ceramic object,

marked with strange engravings.

If you look carefully

at the surface,
you see little daggers.

The use of these daggers

like this is usually
some kind of exorcism

that's taking place

to get rid of some sort of
evil or maleficent spirit

that happens to inhabit a place.

"Dagger" describes the object

that's called in Tibetan phurba.

A stake, basically.

And it's... like any spike,
the fundamental purpose

is to hold something down,

to stab it ritually and
make sure it stays down.

Mark believes the dagger object
was left

by later visitors to the cave,
probably early Buddhists

performing an exorcism in
reaction to finding the bones.

They enter these sites

at some time in the past
after the people

have been buried in them.

They encounter the bones,
and then they

become frightened by them.

If this interpretation is right,

the daggers symbolically
hold down the bones,

like stakes, to prevent them
from becoming reanimated.

The remains of the original

occupants of the cave are from
some of the earliest people

yet found.

Mark wants to figure out
where they came from.

For years, scientists believed
these people migrated

from the south,
what is now India,

because it was
much more populated

than the Tibetan Plateau and the
lands to the north, now China.

A discovery in the early 1990s
seemed to confirm the link

to India.

In a cave complex in Mustang
called Mebrak, German and Nepali

archaeologists discovered
the Himalaya's first mummies,

naturally preserved
by cold and dry conditions.

Carbon dating placed
the 42 individuals

as far back as 400 BC.

Since their discovery,

the mummies have been stored
in Kathmandu,

until Mark received permission
to examine the remains.

There's still a little
bit of flesh on it.

You got that right.

Some are still intact,

like this mummified
two-month-old baby.

Some of the bodies
were found on wooden

bunk-like beds,
in a fetal position,

ankles and wrists
bound together with cloth.

No other burials like this have
ever been seen in the Himalayas.

The artifacts look like
they originate from the south,

from what is now India,
and include

ornamental gourds, carved wood,

a bamboo flute, and
even glass beads.

India has been making glass
for over 3,000 years.

This suggests the early people
of the Himalaya

could've come from India.

But it's not that simple.

Each cave burial the team
uncovers in Mustang

is different from the others.

Some are defleshed,
some buried in pits,

and others found on bunk beds.

There are influences
from a number of regions,

so the settlers could have been
from different cultures

across Asia.

There's a mystery here
that can't be solved

by examining artifacts alone.

Many people proposed

different hypotheses
about where the people

initially came from

who colonized
the Himalayan mountains.

But none of these lines
of evidence was conclusive.

What we really needed
was DNA from those first people

in order to solve that problem.

DNA is the double helix strands

of chemicals in our cells that
carry our genetic information

and can reveal what we've
inherited from our ancestors.

If Mark can procure DNA
from the cave burials,

he can find clues
to their origins.

Upper molar two.

A tooth's enamel

is the hardest tissue we have.

It can protect the DNA
preserved within the tooth

for thousands of years.

Mark extracts teeth from
the Mebrak mummies

to add to his samples
from the other caves.

This one was very hard

because it has much flesh
keeping it together.

For the teeth that are
difficult to extract,

he plays dentist to the dead

and uses a rotary tool
to free the tooth

from the 2,300 year-old
mandible.

The teeth go
to Christina Warinner's lab

at the University of Oklahoma.

It's a highly sterile workplace,

built to protect ancient samples

from the modern DNA
that surrounds us.

There is DNA everywhere.

Every time you cough or sneeze,
you're putting DNA into the air.

So if we want to be able
to recover this very ancient

and degraded material,
we have to get rid

of all of that extraneous DNA
as much as possible.

So we conduct this work
in special laboratories

that have highly filtered air.

We have ultraviolet radiation
built into the ceiling

to sterilize the room
in between uses,

and we wear these Tyvek suits,

which help keep our DNA in.

Most people, when they see them,

they're used to seeing them

in context of people
in epidemics trying to

protect themselves from disease.

We wear them
for the reverse reason.

We're trying to protect our
samples from our DNA.

We clean the teeth with bleach

to remove and destroy
any DNA on the surface.

In a way, it's almost like
getting a very belated

dental cleaning.

We use an abrasive tool
to remove the outer layer,

to really scrape off
these contaminants.

And then we use
ultraviolet radiation

that causes damage in any DNA

that's still remaining
on the surface.

We can then liberate the DNA
from the tooth itself.

Tina's meticulous cleaning
methods pay off.

She's found some of
the best-preserved

ancient DNA ever sequenced.

That is extraordinary,

and likely resulted
because the region

is so cold and dry.

100 milligrams

of tooth material,
about the size of a pea,

is all that's needed

to fully sequence a single
human genome...

the genetic blueprint
unique to each of us

that contains traces
of our ancestors' DNA.

We can take these pieces of DNA.

From that, we can
painstakingly reconstruct

the genome of that person,
and learn all sorts of things

about them...
what they looked like,

if they're male or female.

We can learn where their
ancestors came from.

Geneticists can find out

clues to our origins
by looking closely

at small variations

in our DNA and comparing them
to other groups.

Population geneticist
Anna Di Rienzo

found that the genomes
of all the samples

collected in Mustang,
even those from different caves,

are very similar.

One of the major findings
of our study is that

the gene pool
of these populations

hasn't changed in a major way
over the period of time

that we have sampled,
which is roughly 3,000 years.

After comparing the samples

from the cave people
with each other,

Anna then compared the genomes
with different

present-day populations
around the world.

She's looking at small sections
of their DNA for similarities

and differences in the order of
DNA's four chemical bases,

abbreviated as A, C, T, and G.

We can ask with this analysis,
"Who are the populations

that are closest genetically
to our samples?"

Surprisingly, there was no match

with people from any part
of India today.

The results indicated
the Himalayan peoples

are most closely related
to East Asians,

including today's Japanese,
Han Chinese, Tibetans,

and the Sherpas,
who live near Mount Everest.

So the earliest Himalayan people
came from the north,

from East Asia
and the Tibetan Plateau.

Although their burial customs
differed from one group

to another, and some
had artifacts from India,

and lived at different times,
genetically, all the cave people

were very close.

The genetics were incredibly
stable through time.

This was fascinating to us
because we saw big changes.

For example, between the Mebrak
and the Samdzong period,

we suddenly see defleshing.

That's a new thing,
that's a religious change,

and yet we don't see any change
in the underlying genetics

of the population.

But researchers have spotted

one genetic change specific
to high-altitude peoples

of the Himalaya.

It's an ancient mutation,
or gene variation,

a change in the order
of the chemical bases...

the As, Ts, Cs and Gs
that make up the gene.

The variant prevents people
from getting sick

at high altitude where the
available oxygen is low.

There are a few places

in the genome, a few traits
in which we have experienced

very recent evolution.

So one of these would be the
adaptation to high altitude.

There's only a handful
of these genes that are very,

very recently
undergoing selection,

and this is one of them.

Most of the Himalayan people
that live here now

have this variant.

The team wants to know
if the ancient people

buried in the caves

also had this mutated version
of the gene.

To gather even more DNA samples,

the team heads to another
burial site,

in a region called Nar-Phu,

where there are reportedly
hundreds of bones.

Although it's only 30 miles away
as the crow flies due east,

getting there
takes three days of driving

and another three days on foot.

It'll take ten hours to hike
to 12,000 feet in a day,

a rapid 4,000-foot gain
in elevation...

not enough time for most people
to acclimatize,

or adjust, to the altitude.

Now, you'll see
as we're walking uphill,

steadily gaining elevation, we
have to breathe a lot heavier.

Might just feel like our
performance is really down.

Now, a lot of the locals
don't really feel that,

because they have that special
makeup in their DNA,

and it allows them
to acclimatize very quickly.

Meanwhile we're out of breath.

We're definitely feeling
a lack of performance.

We might feel like we have
a little bit of a headache,

a little dizziness.

There's about 35% less oxygen

available here
than at sea level,

so the team keeps track
of how much oxygen

is getting into their
bloodstream

as their bodies adapt.

We're at Meta, which is at
about 11,700 feet,

and we're just
going to be checking

the level of
oxygen concentration

in the bloodstream
with a pulse oximeter.

The lower number
is the pulse rate,

and the upper number
is the percentage of oxygen

that's being carried
by the blood.

When we breathe,

oxygen enters our bloodstream
and provides our cells

the fuel they need
to carry out their jobs.

At sea level, a healthy person

should have at least 95% oxygen
saturating their blood cells.

But at 12,000 feet,
lowlanders who first arrive

will only have
between 80 and 90%.

There is about an 82%

carrying capacity of O2,

percentage of oxygen
in the bloodstream currently.

And their pulse
is at about 108, 109.

These are fairly common numbers,
actually, for arrival

at altitude.

For unacclimatized folks.

For an unacclimatized person.

Yeah.

If Mark were at sea level,

82% would be a low blood oxygen
saturation, called hypoxia,

and he'd be given
bottled oxygen to breathe.

But at altitude,
this figure is normal.

In contrast,

Himalayan people can tolerate
low levels of oxygen,

thanks to a genetic trait.

Somebody who lives at altitude

that's got the appropriate
genetic adaptations,

I'd expect their pulse rate
to be lower.

I'd also expect
their oxygen saturation

to be significantly higher
than folks like me.

I guess we'll test that now.

Temba, where were you born?

I was born
in the Everest region,

which is elevation
about 12,600 feet.

My expectation is that
Temba will have a relatively low

pulse rate, and he'll also

have a relatively high
oxygen saturation in his blood,

because he's adapted to high
elevation life genetically.

Your saturation is what?

I can't see it very well.

92, 91.

And his pulse rate is 78.

You know, pretty typical
for folks that are adapted

to this kind of life.

If most of the people

living here today
have this genetic variant,

the question is, when and where

did this adaptation
begin to appear?

The team moves ever higher

into the cold and arid
alpine zone

at 13,000 feet.

It's a wonder people
came to settle here at all.

The villages are abandoned
as locals have gone

to higher pastures for foraging.

Life is hard here,
which is why the Himalayas

were settled so late.

If you look at the pattern
of human migration

over the last two million years,

mountains are one of
the last places on the planet

to in fact be occupied.

Deserts come earlier.

Polar extremes, like
around the Arctic Circle,

come somewhat earlier as well.

Mountains come somewhat later.

These are difficult places
for people to live.

They've reached their
destination of Kyang.

The village feels
like a ghost town.

There's really nobody around.

I walked through
just trying to talk

with some people,
but it didn't look like...

I mean, there were a few
donkey people just around

the corner, but they left
about 15, 20 minutes ago.

These are the same pastures

the early inhabitants
used for their animals

thousands of years ago.

Somebody lived here
some long time ago,

built the site,
and buried their dead

somewhere around here
on these relatively fertile

pieces of ground surrounded
by these incredible

vertical environments.

We will have to find out
what the dates are,

and if there's any
associated artifacts

that give us a sense
of what this group of people

might be related to.

Because right now they're
essentially unknown to us,

except for the fact
that they exist.

The team is anxious

to see if Pete
can get inside the cave.

We can watch with the GoPro

what Dad's doing,
filming, on here live.

About 800 vertical feet
above the village

is the naturally occurring cave
with manmade walls

stacked above it.

Work our way up,
like from the right,

up and around the cleft.

Pete's objective

is to get safely inside
to photograph the interior.

We're at the base
of the big crack now.

It's just that it's exposed,

and there's a lot of loose rock
stacked up on the ledges.

If you grab the wrong handhold
or foothold

you could send a big rock down
or you could fall.

Pete free-climbs the large crack

leading deep into the cave.

He'll place an anchor above him
for a safety rope if he falls.

Going up into the cleft

and way back into the dark
wearing a respirator mask

and a headlamp,
it can be very narrow.

I can certainly get very
claustrophobic moving in there.

It's very dusty inside.

There's a lot of remains
from birds and bats

and every manner of rodent
in there.

You're just inching your way
up through this crevice,

and then you enter this very
spacious bone room.

It was very much crypt-like.

Hey Mark, you guys copy?

Yes, we copy, Pete.

I have a couple of jaws here,
couple ephemera,

and then a few other
human pieces.

A piece of wood
that's pretty interesting

that are all in a bag
right here we'll collect

on the way down, break.

The climb is too technical

for the scientists
to get inside.

So, Pete maps out
sections of the cave

on a grid, and all bones
and artifacts are bagged

according to their location.

The process with the grid

that we're lining out
is really just to try

to give the archaeologists

an idea of where in the cave
these materials

were actually taken from.

The original burials

have been disturbed,
most likely by looters

looking for valuable
funerary goods.

There's a real scattering
of materials.

It looks like someone
had actually been

doing some digging right down
in this area to my left.

So we're looking at a context
that's more disturbed

than I had anticipated.

It takes three days

to fully excavate
every bone and artifact

from the cave.

Okay, I've got the bag,
if you guys pull.

The next step

is to look for signs
of death rituals.

People's heads.

People's heads, yes.

The presence of animal bones

suggests they were sacrificed
to bury with their human owners.

This is a very common pattern

in this part of the world, is to

inter the dead
with domesticated animals

of one kind or another.

Here in Kyang the only ones
that we've seen so far

are sheep or goat.

If you find animals
in a grave like that,

there's got to be
a reason for it.

It's most likely that
the animals were sacrificed

and placed with the dead person

for one of two reasons...
either to be food

in the next life, to constitute
part of his or her herd,

or as the animal that guided
the dead in the afterworld.

Every scrap of evidence
is analyzed.

It's definitely been

imprinted on there somehow.

Good eye, Finn.

I bet if we wet it in water...

Oh yeah, check it out.

There it is.

Can you see it more clearly?

Very nice artefact.

It's a simple bamboo stick,

but the woven pattern on it
suggests it was once

part of a basket.

Later, carbon dating
reveals the people of Kyang

lived around 200 BC...

the same time
as the Mebrak mummies.

Their artifacts appear
to be locally made,

indicating the people
were self sufficient

and lived off the land.

The bamboo and wood
could've come from nearby.

This is a very nice wooden bowl.

Soft wood.

It has a really lovely
little base on it

that's been made,
and it imitates a bowl

that's been made on a wheel.

So it's been carved
to look like that.

Jacqueline determines 23 people

were buried in the Kyang cave,
with no cut marks,

and the presence of flesh
on the joints suggests

they were buried whole.

But the ages of the dead
are surprising.

Several of these individuals
were younger than 20.

Several of the adult remains

are also younger adults,
so below the age of 30, 35,

and that suggests
that people did die

of something that
shortened their lives.

Could be starvation,

could be an infectious disease

that, you know,
moved really rapidly.

An enigmatic object
found in the cave

hints at ritual practices
that may be connected

to these premature deaths.

One of the most
interesting things we found

during this work here at Kyang

is this special stick.

You can see it's well-carved.

It's thin at the bottom,
widens out.

Clearly it's been meant
to either be put in the earth

or maybe in a socket
of some kind.

The first thing that jumps out
when you look at this

under the microscope

that we have here in the field
is those are little tiny pebbles

that have been placed inside
little tiny divots.

And the divots are holding glue,

some kind of cement
that hold these things in place.

But if you look at this image,
it's the image of a person.

What I really think
this person is doing

is holding something we found
in the archaeological site,

what I've been calling
fire sticks.

They're little sticks.

They might be four or five
inches long,

and usually one end is burned.

You can see the wavy
or sinuous line, which I would

interpret as smoke coming out
of the end of that firestick.

Cultural artifacts

open a window on a people's
long-vanished beliefs.

The humanoid figure on the stick
is so unusual,

Mark travels to France
to see if anthropologist

Charles Ramble
can make sense of it.

Charles specializes

in the ritual practices
of Himalayan peoples.

What's the material?

This is not just discoloration
from water or something?

No, not at all.

That's actually...
what they've done to highlight,

they've ground up
some dark stone

into very fine particles,

and then literally pushed it
into the outline of this

to kind of emphasize
and bring out the contrast.

So all this was intended.

All this was very much intended.

Charles has recently discovered
an ancient text

that describes a death ritual
using sticks called firebrands,

much like the ones Mark found.

Tibetans believed

that people died because
their souls were taken away

by death demons.

And these are known variously
as shi or as shay.

Shi is commonly translated
as "vampire."

And rituals had to be
performed afterwards in order

to separate the soul from
the demons who had taken it.

"I am Taklamembar,
and this is how

"the vampire-killing firebrand,
the emanation of my mind,

"came into being.

"The demon of bad death
among males was killed

"with the firebrands.

"The demoness of bad death
among women was killed

with the firebrands."

There is one text...
its title translates as

"The Origin Tale
of the Firebrands

for Killing Vampires."

These firebrands in this text
are being used

as a means of killing vampires,
and vampires are the agents

that are responsible for death.

They are serial killers.

So if people of a certain age
between 20 and 30

die in a series,

that's the effect of vampires.

So the vampires are something

that steal vitality,
and eventually life.

And they latch themselves
onto a family,

and they will continue

to affect that family
until they are got rid of.

This may explain

why the firestick was found
in the Kyang cave

with young adults
who died prematurely.

It's unusual that we can find

textual evidence to support
archaeological evidence.

"The killing of vampires
with the firebrand is over.

"May there be good fortune,
good luck, blessings,

and virtue."

Stakes of this sort
are very ancient.

They've been found

in many parts of central Tibet,
and also at the foot

of the Great Wall.

And they date back
to the third century BC.

The discovery of stick effigies

at the foot of
China's Great Wall

is another piece of evidence
confirming these people

could've come from there.

With DNA recovered

from each cave population,
the scientists can see,

over a 3,000-year timespan,

which of them was adapted
to survive at altitude,

and when the adaptation
appeared.

An important feature

of the study is that it provides

ancient DNA samples and data
from different time points

in the past.

We can see how the data
changes over time.

And this is what we call
watching evolution in action.

Anna finds that all

of the people
buried in the caves

have the high altitude
adaptation.

But the study
of their DNA reveals

there's a second adaptation

that also enables people
to live at altitude.

The earliest of the cave people
have the first genetic variant,

but the most recent burials,
the Samdzong people,

acquired a second variant.

Both variants are seen

in the people
of the region today.

The most surprising aspect
of this variant

is that scientists
have seen it before.

In 2008, the tiny pinky bone

of an extinct human ancestor
was discovered in a cave

in the Altai mountains of
Siberia, called Denisova.

The 41,000-year-old pinky bone

had just enough DNA in it
to be sequenced.

The individual was female,
young, and had that

second adaptation.

This Denisovan population

that had a relatively wide
geographic distribution in Asia,

maybe they already had adapted
to high altitude.

That's part of the history
that we would like to dissect.

At some point in prehistory,

Homo sapiens,
our modern human species,

must have mated with the
now-extinct Denisovans.

It's likely the only way
humans could have obtained

the second high altitude
gene adaptation.

We don't know exactly
where the encounter

between this Denisovan-like
population

and the modern human populations
occurred.

It's possible that
this mutation was present

in the Denisovan-like population
but was not advantageous,

yet after the mixing
between these two,

and the modern human population
moved to high altitude,

it became advantageous.

This important DNA variant,

or allele, from an extinct
human ancestor, is part

of the genetic inheritance
of Himalayan people today.

The finding was very exciting.

It's telling us something more
than just the fact

that modern humans

and Denisovans mixed,
but also that

Denisovans gave modern humans
an allele that allowed them

to conquer this so-called
Third Pole,

and to adapt
to these very harsh conditions

of high altitude hypoxia.

Genetics and the study of
ancient DNA

allow us to see modern
human evolution in action.

This new ability that we have

to actually sequence
ancient genomes is teaching us

so much we didn't know about
human history

and prehistory.

So, already, we're rewriting
the storybook of humanity.

We're definitely still evolving.

The point at which
we stop evolving is when

we're an extinct species.

That's the end of evolution
right there.

Those slight changes give us
the ability to adapt

to changing
environmental conditions.

Here in the Himalayas

we can trace
how we evolve over time.

That the people here
can thrive at altitude

shows just how adaptable
we as a species can be.

We now know more

about the early cave peoples'
beliefs, and how they endured

one of the toughest places
on Earth.

And the knowledge gained

by recovering ancient DNA

and deciphering death rituals

provides a clearer picture
of the unique heritage

of the mountain peoples who live
at the roof of the world.

This NOVA program is
available on DVD.

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