Nova (1974–…): Season 46, Episode 9 - First Horse Warriors - full transcript

The advent of horse riding changed the course of human history and the genetic makeup of humankind.

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Horses.

Powerful,

graceful,

and thunderously fast.

No animal has made
a greater impact on society

or given humans
more freedom and mobility

than horses.

The thrill that people
still get today

from riding a horse
at top speed,

there's nothing like it.

Whereas if you get on the back
of a cow...



it's not that great
an experience.

Centuries before
Egyptians built the pyramids,

Eurasian nomads unlocked
the power of horses

and used them to reign supreme

over vast territories
of the ancient world.

But how did they do it?

Follow anthropologist
Niobe Thompson

as he visits the last
of today's horse-riding cultures

and explores
archaeological sites

and genetics labs seeking
to unlock the mysteries

of the world's first riders.

The horse transformed
what it means being human.

It gave the possibility
to explore the world

in a way that
had never been possible before.



But horses could also
bring terror

at the hands of brutal raiders,

and even pandemic disease.

Time-travel back

to when prehistoric people began
capturing wild horses

and rode them like a tide

that would forever change
the course of human history.

"First Horse Warriors,"
right now, on "NOVA."

Major funding for "NOVA"
is provided by the following:

Horses are magnets
for our attention.

They draw us in,

almost demanding
we look at them.

For most people today, just
seeing a horse is a rare sight.

Perhaps
only a couple of times a year,

watching races
like the Kentucky Derby.

But not so very long ago,
horses were everywhere...

Woven into the fabric
of our daily existence,

in the countryside

and even in cities.

The city of New York had
tens of thousands of horses

that were doing all the work
that trucks do.

And they were also doing all
of the work that taxis do today.

We don't depend on horses
anymore,

but few animals have been
as important

to the rise of civilization.

For thousands of years,

they were
our long-distance vehicles...

The muscle and speed we needed
to master the world.

But how did
this unique partnership form?

Who were the first people
to unlock the power of horses,

and what happened once they did?

Recent discoveries
in archaeology and paleontology,

genetics, and even linguistics

are revealing the identity
of the world's first riders,

as well as
the extraordinary relationship

humans forged with horses

and how that bond would change
the very course of history.

Horses appeared on the scene
long before we did,

but surprisingly, looked nothing

like the majestic creatures
we see today.

55 million years ago,
they are small,

and move like agile dogs.

This Dawn Horse is well suited

to the tropical forests covering
much of the Earth back then,

living and foraging
among the dense foliage.

It stayed hot
for millions of years.

And in all that time, Dawn Horse
hardly changed at all.

And then,
about 15 million years ago,

the Earth began to cool.

And when it does,

forested regions
distant from the Equator

transform into open plains
covered with grasses.

And here,
the small, dog-like horse

evolves to avoid predators,

growing sleek, tall, muscled,
and fast.

Although horses first appear
in North America,

as their numbers grow,
they migrate across Beringia,

the land bridge that
once connected the continents.

More than 100,000 years ago,

herds of horses
in Europe and Asia

prove a rich source of meat
for Stone Age hunters.

People hunted horses.

They are meat on the hoof.

They don't have sharp teeth.

It's not like hunting
cave lions, you know?

And early hunters know
how to find migrating horses.

Horses are relatively
predictable animals.

And they tend to follow
a regular system

of water holes
and grazing places.

At Solutré in Central France,

there's evidence ancient hunters
regularly ambushed horses.

At Solutré,

for about 20,000 years,
people were driving wild horses

into a kind of cul-de-sac

and then killing them
with spears for food.

This chunk of earth excavated
at Solutré

is dense with horse bones,

revealing just a tiny fraction

of the tens of thousands
of horses

slaughtered here
over the centuries.

At Chauvet Cave
in Southern France,

the importance of the horse
to our Stone Age ancestors

is on clear display.

When you look
at this marvelous wall,

you see all the major animals
the Stone Age world depicted.

You've got reindeer
and mammoths, big cats.

But the horse seems to play
the most prominent role.

From their art,
many experts believe

ancient humans were making
a spiritual connection

to these animals.

Despite such reverence,

prehistoric humans may have
over-hunted horses,

and by about 10,000 BC,

when a changing climate may have
also depleted their numbers,

horse herds became scarce
in Europe

and disappeared entirely
in the Americas...

where they would not return

until European explorers
sailed them back in ships.

But on the grassy steppe lands
of Central Eurasia,

the descendants of horses that
migrated from America flourish.

And it's here
that many experts believe

prehistoric humans eventually
discover how to ride them.

The steppe refers
to this long grasslands plain

stretching over 5,000 miles
from the edge of today's Europe

all the way to Mongolia in Asia.

It's a harsh environment...

Cold in the winter,
hot in the summer,

and in many places,
too dry for agriculture.

But you can pasture animals,

and these Kazakh herders are
following in the footsteps

of their nomadic ancestors,

who may have been
among the first people

to capture and ride horses.

And Niobe has come here to see
what he can learn from them.

Raising sheep, goats, and cattle

is a rugged, outdoor existence.

But horses make herding easier...

Especially when moving
grazing animals to new pasture.

And Niobe pitches in.

It was surely a big change

to turn wild and wary
steppe animals

into the working horses
we see today.

So who were the first people
to tame wild horses,

and how did they actually do it?

5,500 years ago,

the people who lived
at this site in Kazakhstan

may have been the first culture
to master the horse.

The site was discovered
40 years ago

when Russian archaeologist
Victor Zaibert

noticed circles in the earth

that turned out to be
large houses

belonging to a steppe people
anthropologists call the Botai.

Prior to creating this village,

the Botai are strictly nomadic,

living off the land,
foraging and hunting,

and eating what they could find.

But then they settle down
and change their lifestyle.

By the vast number of horse
bones uncovered at the site,

they began eating horsemeat
almost exclusively.

But is eating horses

the only use the Botai had
for these animals?

Or could they be riding them,
as well?

That question has roiled the
academic community for decades.

Almost got a bevel on this side, too.
This is the same guy?

Anthropologists David Anthony

and his wife, Dorcas Brown...

There's the skull...

have long maintained

the Botai were among
the first people

to capture and ride horses.

And they've pieced together

what they believe
is convincing evidence

by looking for wear marks
a riding bit might make

on their teeth.

A bit is part of
the bridle or reins.

They can be made
of leather or metal,

and they go in the horse's mouth

just here.

So when I apply pressure
through the reins,

the bit tells the horse
what I want it to do.

And David Anthony believes
he's found evidence of bit wear

in the jaws of Botai horses.

There is a gap between
the molar row and the incisors.

And if you put a bit
in the horse's mouth,

it sits on top
of very sensitive tissue.

And so by pulling on the bit
on one side,

you pull the bit down
against the gum,

and the horse will turn its head
in order to avoid that pressure.

You pull the rein
on the other side,

and the horse will turn its head
to avoid that pressure.

And that's how a creature
as puny as a human

can control an animal
the size of a horse.

But a horse doesn't want a bit

constantly bearing down
on its gums.

The horse can use its tongue

to push the bit up
and put it onto these teeth

to get it
off of the soft tissue,

where it can't hurt them
anymore.

And then in this position,

if the horse grasps the bit
very firmly

between the lower teeth
and the upper teeth,

it can keep the bit off
of its tongue and gums.

So we were looking for wear

on the front part
of the tooth here.

They examined hundreds
of samples,

looking for evidence
of bit wear...

You can see that it's broken.

He really, he chewed all the way
through this bit.

And feel confident
they found it.

This is a cast of a tooth
from the site of Botai

that's 5,000 years old.

This is the tooth of a modern
horse that's been bitted.

And both of them have wear
on this front cusp right here.

Despite this apparent evidence,

not every expert believed
Anthony was correct.

There are people

who did not believe

that the marks that we saw
on the teeth

were caused by a bit,

because those kinds of features
can be caused

by natural malocclusion
in horses.

Beside refuting
the bit evidence,

other experts argue that images
of humans riding horses

or chariots

do not appear
until about 2000 BC,

or 1,500 years after the Botai.

If the Botai had become riders,

surely this would have been
depicted in art.

This is the same guy?

So are Anthony and Brown correct

about teeth wear as evidence
for riding?

Archaeologists digging
at Botai village

have been hoping to find
other evidence

that the Botai
had become riders.

They know the people are
smoking, cooking, and eating

vast quantities of horsemeat.

And they found large
concentrations of horse dung

and holes from fence posts,

indicating the Botai are keeping
horses in corrals...

Something David Anthony believes
makes sense

for a culture that had become
dependent on horses.

It's easier to kill a horse
in a corral

than it is to find the horses,

go out to the place
where you have to ambush them,

kill them there,

and lug it back
to your settlement site.

It would be
a lot more convenient

if you just had horses
in a corral,

and you could go out and get one
whenever you wanted a meal.

Beside serving as a food larder,

the corrals could also mean

the Botai are breeding
and domesticating horses,

like other cultures are doing
with cattle, sheep, and goats...

Living off these animals
for milk, meat, wool,

and other products.

If the Botai
are domesticating horses

for the same reasons,

this would naturally bring
greater interaction

and familiarity,

making attempts to ride them
much easier.

And archaeologist Alan Outram

set out to prove the Botai
had domesticated horses

by focusing on milk.

If people could milk cattle
very early on,

then people that were
living off horse products,

why would they not
also milk horses?

And if you've got horse milking,

you've got a smoking gun
for domestication,

because no one's going to argue
with you

that people are running
after wild horses to milk them.

If the Botai had been milking
tame horses,

these broken pottery vessels may
have once contained their milk.

So Outram brings them
to this lab

at the University of Bristol.

Be a drop
in horse populations...

He wants chemist
Richard Evershed

to use a process called
an isotopic analysis...

Be interesting to know what
this little blip is down here.

To see if he can find
residues of milk fat

still clinging to the pottery,

even after 5,000 years
buried in the ground.

The basis of what we do
is to look

at the organic compounds,
the fats,

that have absorbed
into the wall of the pot.

And actually, they are
pretty tough to extract.

And we've had to develop
some methods

to actually open up
the structure.

At first, it's all handwork.

We drill off the surface
of the pot

to reveal a, sort of
a fresh ceramic surface.

And then we literally break off
a small piece,

about two grams,

and we put it
into a pestle and mortar,

and we literally grind it
to a powder.

We pound it to a fine powder.

And what that is doing is
opening up the pores in the pot.

This will hopefully free traces

of specific
chemical fingerprints,

called isotopes,

of any organic substance
the pottery once contained,

including milk fat.

The powder is then liquefied

and placed into this machine

that heats it and analyzes
the chemical signature

of the gas vapors being released

to see if those signatures match

the ones known to come
from horse fat.

So these are the results
of the isotope analysis.

And you can see

these two major peaks.

And these are the fatty acids

that tell us we've got
an animal fat.

A good start.

But evidence of fat doesn't
necessarily mean milk fat...

It could be carcass fat.

We can't say
from just looking at these peaks

exactly what type of fat
we've got.

And since the Botai
are eating horses...

And if you're cooking meat
in a pot,

you will obviously get
the deposition of a lot of fat

as the meat is cooked.

So that didn't work.

Yeah.

They go back
to the drawing board,

realizing they need a way
to clearly distinguish

milk fat from carcass fat.

And the best way to do that

would be to go to the original
Botai environment in Kazakhstan

and gather samples
of mare's milk.

The grasses mares eat today

should be composed of elements
like hydrogen or oxygen

that are similar to those
their ancient ancestors ate.

It's the "you are what you eat"
principle.

So you're inheriting
the isotope signatures

of different foodstuffs
that you're eating.

In spring,
when mares are nursing,

their milk absorbs
elevated levels

of a hydrogen isotope
called deuterium

that's in water and grasses.

And this elevation will only be
in the milk fat,

not in their carcass fat.

When the team analyzes
the modern milk samples,

they find
elevated deuterium peaks

that match perfectly
those from the Botai pottery.

This confirms
Alan Outram is right:

The Botai had been milking
domesticated horses.

I don't think
anyone can seriously argue

that you haven't got
decent control of animals

if they're being milked.

But it takes practice
to milk a horse,

as Niobe discovers.

Milking a horse
is all about tricking the horse.

So what happens is,

someone brings a foal in,

the foal sucks the milk
from the teats,

the milk falls,

and then they pull the foal away
quickly,

and someone rushes in
and milks the horse.

As soon as the mare knows
that it's not the foal,

or suspects something,
something's different,

the milk dries up.

The mare sensed

that I didn't really know
what I was doing,

and as soon
as I got a bit of milk out,

the teats dried up.

They had to bring the foal
back in.

It's really hard.

You know, it's just...

Just a little bit.

Only horses used
to a human touch

would have allowed the Botai
to milk, tame, and ride them.

And so by the time you start
to pile all of this evidence on,

the people living
in sedentary villages,

milking the mares,
eating the horsemeat,

it's fairly evident

that you have
domesticated horses there.

And gathering large herds
of domesticated horses

would be extremely difficult

without horse riders
to herd them.

If you ask people
who manage horses today,

"How can you manage horse herds
without riding horses?",

they laugh at you.

Of course
you have to be on horseback

to manage herds of horses.

So despite their doubters,

all the evidence points to
Anthony and Brown being correct.

The Botai were riding horses.

But how did the Botai convince
large, wild animals

to let them climb
on their backs?

You choose the docile animals.

So you would approach a horse,

and if it ran away,
you didn't get it.

But if you approached a horse,

and it was sort of curious
and interested,

then you could then begin
with that horse

and then go,
build on from there,

build a whole herd from there.

Oh, I think the first riders

were getting bucked off
pretty fast.

But once they figured it out,

why not go long distances?

Especially on the steppes,
you know?

You'd always wonder
what's over that next horizon.

I think
that's what was going on.

They wondered what was past
that next horizon.

Riding.

The Botai's prey
has become their companion.

Riding this magical creature

must have felt
like breaking a law of nature.

Now the Botai can herd
more animals

and trade with distant cultures.

Their horses prime them

to become the most
dominant force on the steppe.

You would expect
the Botai people,

with the advantage
of horseback riding,

to have really thrived.

And it looks like
they did great.

They had these large
conglomerations of people

living in these big settlements.

They were feeding themselves
magnificently.

But after 3000 BC,
they pretty much disappeared.

What became of the Botai
and their horses?

Archaeologists have found
little evidence

or even human remains
in the village

that might help them understand
their fate.

And that's what makes this
discovery by Alan Outram's team

so important:

a fairly intact Botai skeleton.

I cannot stress how rare
human remains are at this site.

Their hope is that
these bones will yield DNA

that geneticists can trace
to later populations

that may have absorbed the Botai
and become their heirs.

Recovering ancient DNA
is extremely difficult,

but Danish geneticist
Eske Willerslev

has earned a global reputation

for finding
and sequencing the genomes

of our oldest ancestors.

And he's come to Botai village

to see if this rare skeleton
looks like it could yield DNA

that has survived the ravages
of time.

Hey, guys.

Hey, so you found a human whole?
Yes.

But you have no idea how much
of the skeleton is there, huh?

We don't yet.

There are quite a lot of bone
fragments all around.

Some of them are horse bones.

Yeah, yeah.

Eske is impatient to get
specimens back to his lab.

But he'll have to wait
for the meticulous process

of uncovering fragile bones
from the packed earth...

And then hope for the best.

We are getting DNA
out of a lot of specimens

that we, six, seven years ago,

didn't think you could get
anything out of

whatsoever, right?

And now they're working.

So, I mean,
it's really hard to predict

whether the specimen
will work or not,

but I'm pretty optimistic.

When you have cleared the head,

can we kind of
remove the lower jaw

to get a tooth?

I think the lower jaw
will come away all right.

All by itself, huh?

Yeah.
Yeah.

Eske wants a tooth,

because the DNA inside

is protected
by an outer coating of enamel.

The team gives him one.

Wow, okay, this is beautiful.

This is beautiful.
This is beautiful.

Oh, this is fantastic.

Yeah!

Amazing, yes.

Thank you very much.

You're very welcome.
Yeah, yeah.

And there's something else.

Oh, hey,
there's a petrous there, right?

Yeah.
Wow!

The petrous...

A small bone that's part of
the skull near the inner ear...

Is a fortuitous find.

So the petrous bone is the most
dense bone in the human body.

Therefore
the DNA preservation is better

than in other parts
of, you can say,

the post-skeleton material.

After months of work,

Eske and his team identified
the genetic signature

of the Botai villager.

They expected to find traces
of his genome

in later steppe cultures.

But stunningly,
they couldn't find it.

The Botai people, if you want,

as far as we know, haven't left
any direct descendants.

Despite their resources
and well-established community,

the Botai somehow died out.

It's kind of tragic irony

that they do something
extremely challenging...

They domesticated the horse,

probably one
of the most influential events

in human history.

But they don't
take over the world

with this new, major power
they have.

I mean, they become a dead end,
right?

They don't have an impact.

As it turns out,

we know more
about the fate of Botai horses

than the Botai people.

French geneticist
Ludovic Orlando

has also come to Botai village

to collect bones
for DNA sampling...

In his case, horse bones,
not human ones.

If these are indeed the remains

of the world's
first domesticated horses,

then Orlando believes
it's very likely

their genetic signature
will have passed on

to all domesticated horses
living today.

He took samples back to his lab

to see if his theory
was correct.

I was expecting the first
population of domestic horses

to have been the source

of all and every possible
domestic horse

that lives on the planet today.

But when he ran the tests,

the results came as a shock.

I have no way to express
how wrong I've been, actually.

When Orlando sequenced
the Botai horse genome

and looked for its signature
in modern horses,

he couldn't find it,

as if the Botai horses,
like their masters,

had disappeared.

But then, in a surprising twist,

he found them in the least
likely horses imaginable.

The big surprise is that
it's the Przewalski horse.

The Przewalski horse.

For centuries,
these unique-looking horses

were thought to be the last
and only wild horses on Earth,

living in a remote area
of Mongolia.

As it turns out,

they are the genetic descendants
of Botai horses

that returned to the wild
when their masters disappeared.

So these last of the wild horses

are actually descendants of
the first domesticated horses,

a living legacy
of their Botai masters.

Although the Botai fade away,

another steppe culture seizes
the mantle of horse kings.

They are called the Yamnaya.

Bands of nomads
who roamed a territory

north of the Black
and Caspian seas

at the start
of what's called the Bronze Age.

By about 3000 BC,

they become
the greatest horse culture

of the ancient world.

The most important thing
about the Yamnaya culture

is that they were
the first culture

to take advantage of both
horseback riding plus wagons.

Although the first wagons
are heavy and crude-looking,

they are
a breakthrough technology.

Wagons stocked
with food and supplies,

accompanied
by horse-herded flocks,

allow the Yamnaya to easily move
to the best pasturelands.

And in no time,

the Yamnaya are out-competing
other steppe cultures.

The horses helped them
increase their herds.

And so they could get more sheep
and more cattle and more meat.

And so they became wealthier.

Horse herders, could, could beat
everybody out.

And if anyone dares to resist
the Yamnaya,

here, too, the horse gives them
the upper hand...

Literally.

It was an advantage to ride up
to somebody on a horse

and use the horse as a platform.

The height advantage
is a real advantage.

I think we find it
hard to imagine

how thoroughly they could
overcome other populations

who are just sitting there

and unfortunately,
very, very vulnerable.

Over time,

the Yamnaya, and
other cultures they influence,

develop weapons like battle-axes

that are lethal
on or off a horse.

This battle-ax was
a very important piece.

The edge is not sharp.

It's not very good
for, for cutting wood.

But used in battle
for, well, breaking skulls,

it's very efficient.

All over Europe
we find, actually, skulls

which has been, well, broken
by ax blows.

With their horses, wagons,
and weapons,

the Yamnaya and other cultures
they combine with

begin to range ever farther
from the central steppe,

moving as far east as Mongolia

and west
into the heart of Europe.

And David Anthony contends
these aggressive nomads

dominate almost every population
they encounter,

because many people begin
speaking Yamnaya.

Language is connected
to power or to wealth.

People drop the language
they're speaking

and adopt a new language,

because that language gives them
advantages.

But the Yamnaya left
no written record

of their language,

so how could Anthony or anyone
possibly know

what their language looked like
or sounded like?

Andrew Byrd believes these words

are close
to those spoken by the Yamnaya.

He's made up the story,
but can trace the words back

to the time
they were first spoken

and then reconstruct
the language they came from.

Linguists have long maintained

that many languages
in Europe and Asia,

including
Ancient Greek and Roman;

Romance languages
like French and Spanish;

Germanic languages,

including English
and the Scandinavian languages;

even Russian
and Indian Sanskrit,

all derive
from a common language source.

If you look at languages like
English and Latin and Greek,

Sanskrit and Russian,

and you start to see these words
looking very, very similar

to one another.

For example, if you look
at the word for brother,

within English, it's "brother."

If you jump down
to ancient Rome,

it's "frater,"
as in our word fraternity.

If you go to ancient India,
it's "bratar,"

and if you go to ancient Greece,
you have "pratar."

And you could see

that these words look
so overwhelmingly similar.

They have Rs after some sort
of B- or P-like element.

They have a T sort of thing
in the middle of the word.

They all end in R.

And, and the fact that all
of these things look alike

can't be by chance,

leading us to the...

The only sensible conclusion
is to say

that these all were inherited
from an ancient language.

Linguists call this source
language Proto-Indo-European.

They can take a word like "is"

and trace its spelling
and sound pattern

back through past languages

to approximately
when the word first appeared.

They can do this
with many words,

like "father."

And most seem to originate in
the period of Yamnaya expansion.

And some words, like "wheel,"

connect directly
with the Yamnaya

and only appear after
the Yamnaya become dominant.

You can establish that the
later Indo-European languages

all expanded after 3500 BC,

because they have the wheel
and wagon vocabulary.

And wheels and wagons
didn't exist.

They had to be invented first.

It's very much like the word
"hard disk."

It shows up in dictionaries
in 1978.

And dictionaries before 1978

didn't have the word "hard disk"
in them.

Because it hadn't been invented
yet.

And so Proto-Indo-European
must have been spoken

after wheels were invented.

Therefore, we assume that there
was some ancestral language

which we can call the Yamnaya,

which was the source
of all of these languages.

But how did these bands
of nomads

overwhelm other cultures
so completely

that people began speaking
their language?

Shouldn't there be
some indication

they had become conquerors?

There is very little evidence

that what happened
4,800 years ago

is related to violence,

that there was a massive amount
of warriors coming in

and just, like, stabbing
and killing everybody,

because we don't find evidence
for that.

So how did Yamnaya language
and culture

spread across Europe and Asia?

Is there something more tangible
than language

to account
for their dominant presence?

Back in Copenhagen,

Eske Willerslev had long puzzled
over the question:

"Which ancient cultures
were most responsible

for the ancestry
of people living today?"

Our history

far back in time

is actually written still
in our genes,

and that means you can,
you can follow human history

by analyzing the genome
of these ancient individuals.

He was especially curious
about the Yamnaya.

If they had dominated
large parts of Europe and Asia,

then their DNA should have
passed on

to future generations,
down to the present.

His team began

by sequencing ancient remains
from across Eurasia,

and then comparing them
to a Yamnaya genome

to see how widely
the Yamnaya genes had spread.

They then compared this data

to the genomes
of modern populations

and put the results
on what are called PCA plots.

PCA is a way of understanding
very simply and visually

the differences
in genetic ancestry

between populations.

For example,

you put a bunch of people
from Europe on a PCA,

and you'll notice

that the people in Northern
and Southern Europe separate.

The second thing you want to do
on this

is to overlay
ancient populations

on top of the modern populations

and see where they lie.

These two plots
show modern population groups

as gray dots in Europe
and Central Asia.

When we overlay the genomes

of people who lived 10,000
and 8,000 years ago,

we see almost no overlap,

indicating little
genetic connection

to people living today.

But in this plot...

Representing
the approximately 5,000-year-old

Yamnaya expansion,

the dots overlap significantly,

meaning today,

millions of people of European
and Asian descent

owe their ancestry
to Yamnaya nomads

of the Eurasian steppe.

What we didn't understand
from the archaeology

is the extent of the movement
and the impact

that the Yamnaya had
on genetic ancestry.

But now we know that up to 50%
and 30%, respectively,

of the genetics of Europe
and South Asia

are directly descended
from that of the Yamnaya.

So the impact is huge,

as much as any
genetic ancestry that we have.

And the Yamnaya
could not have made

such a massive
and wide-ranging genetic impact

without their horses and wagons.

Anthropologists like Anthony
were right

that the early Bronze Age
is characterized

by this very significant
movement of the Yamnaya peoples

on horses that are very speedy,
very fast

into Northwestern Europe
and Central Asia,

and bringing with them,
of course,

the genes, the culture,
and the language.

But the majority
of archaeologists, you know,

didn't believe
this was the case.

Six-and-a-half years old...

For Anthony and Brown,
this was vindication.

The Yamnaya had been
masters of their universe.

We were very happy.

We were smiling and laughing,

and going, "Oh, my God,
I can't believe it's that big."

But I was pretty sure these guys
were roaming all over the place.

But a big question remained.

It appears
Yamnaya numbers are small

compared to the size of the
populations they encountered.

So despite the advantage
their horses gave them,

Eske wondered
if there could be other factors

that weakened
the populations they dominated.

At first we thought,

"Well, maybe it's some kind of
climatic changes,"

and we went, you know,
through the climate records,

and we couldn't really see
anything very dramatically.

And then there was,
one of the archaeologists said,

on the team said,

"Well, what about diseases,
right?"

So we thought,
"Well, let's look for pestis."

Yersinia pestis... the plague.

During the Middle Ages,

this lethal pandemic killed over
half the population of Europe.

If it had struck
during Yamnaya times,

it might have decimated
local populations,

clearing a path
for a Yamnaya takeover.

Eske decided to see

if he could find traces
of the plague

in the bones of the Yamnaya
and the people they encountered.

But he would need lots
of human samples to test.

Remarkably,
in St. Petersburg, Russia,

a rather unique
anthropology museum

had just what he needed.

Some of the museum's displays

have a "Ripley's Believe It
or Not" feel to them.

But the real treasures
are in storage,

as Niobe finds out firsthand.

If you're after DNA from any
part of the former Soviet Union,

this is the place to come:

the museum of anthropology

that Peter the Great founded
over 300 years ago,

the Kunstkamera.

So for centuries,
Russian archaeologists

have been coming back
to these storerooms

with their discoveries.

And today, well,

the collection
of human remains is astounding.

There are hundreds of skulls
and skeletal remains

from different time periods
and throughout Asia and Europe.

Oh, wow, okay.

This is a large collection.

And Eske has convinced
the museum's archaeologist,

Slava Moiseyev,

to let him take back scores
of teeth and petrous bones

to analyze in his lab.

The two men work for days
cutting samples...

Nothing like the smell

of fresh bone in the morning.

Carefully documenting
each specimen

and literally pulling teeth.

Moiseyev has one group
of Yamnaya samples

he knows Eske will want.

This is rather strange burials,

because mostly people
had just single burials.

And this consist
of seven individuals.

It's quite unusual.
Oh, wow.

Group graves became common
for later-era plague victims.

So these samples will go
to the top of the stack.

In the end, the museum...
Like the Tooth Fairy...

Okay.

Bequeaths Eske a goldmine
of samples.

And sure enough,

many contained genetic evidence
of the plague.

We started screening,
and, you know,

bang, it just jumped out, right?

I mean,
so we saw fragments of it,

and then we said, "Wow!"

This is basically evidence of
pestis and plague epidemics...

3,000 years
before any written record.

So it was an amazing result.

The evidence shows the plague
begins in the steppe,

possibly in Yamnaya communities,

and including the family
of seven

buried together
in a single grave.

So clearly at some point,

the Yamnaya themselves
are suffering horribly.

But those that do survive
probably develop immunity.

And as they expand their reach,

they become like the Grim Reaper
on horseback,

carrying plague germs with them.

The plague is spreading
with those people.

Those people actually bring
the plague

into the regions
that they move into.

And where people have
no previous exposure,

only a few survive.

And what happens to those
survivors is an age-old story.

The Yamnaya brought a
really deadly disease with them

that could have been responsible

for a large part
of the population replacement.

There are other ways,
though, of course,

to replace a population,
other than disease.

You can directly kill them.

And it does look like
the survival of males

was much less
than the survival of females.

You find Yamnaya tribes that
regularly engaged in raiding,

killing the men
and taking local women.

And using those women
to produce Yamnaya offspring.

The ancient world could be
a very unpleasant place.

When I started this project,

I had this very romantic view
of, of the whole thing,

and, and kind of, you know,
dreamed about, you know,

living myself
during the Yamnaya times, right?

I have changed that conception.

I'm happy to live now.

The full impact

of the Yamnaya's culture,
language, and genetic dominance

would take centuries,

passing down to other cultures
they combined with.

It's sort of
a slow-rolling process.

It's not like one group
of people

is just packing up their bags
and moving off

to Iberia or England
or South Asia or India,

wherever you want to go.

But they're meeting large groups
of people

who are farming, and,
you know, doing their thing.

And then there's
a hybrid culture that evolves,

and a hybrid genetic ancestry
that evolves.

And these people
then subsequently move

to other parts of the world.

But back on the steppe,

the Yamnaya continue
their nomadic ways

and inspire later steppe people
to take horsemanship

to a whole other level.

If we go back to the steppes
where Yamnaya came from,

horses continued to be
extremely important.

And in fact, a new form
of military vehicle

was probably invented
by the people in the steppes

around 2000 BC...

The chariot.

Pulled by swift horses,

the chariot is
the first high-speed vehicle.

And many ancient cultures
begin using it in battle,

especially on level ground
like deserts.

But the most significant
developments

come
when the great horse cavalries

of first the Huns
and then the Mongols

begin thundering
across the steppe.

These skilled horsemen
could ride and shoot

at the same time

and become
the most lethal military force

the world has ever seen...

capable of bringing armies
and whole cities

across Asia, Europe,
and the Mediterranean

to their knees.

Although these steppe warriors
emerged

centuries after the Botai
and Yamnaya,

their roots go back
to those first riders

and their mastery of horses.

If you just think of some of the
great empire leaders in history,

for example, Genghis Khan,

or Alexander the Great,

so many of them
built their empire

on the backs of horses.

And that of course led
to the spread of civilization,

the spread of all kinds
of technologies,

the Silk Road,
various trade routes.

Everything hinged
on having horses.

The reverence ancient people had
for horses,

revealed first
in early cave paintings,

would continue
for thousands of years.

This bronze and gold
sun chariot,

discovered in Denmark,

perhaps expresses this best,

and is one of the most important
symbols of the Bronze Age.

Here,
the horse is God's partner,

helping pull the sun
across the heavens.

We could wonder

why the horse became the most
prominent helpers of the sun.

But I think the reason is

that the horse was,
and is, even today,

perhaps the most aristocratic
animal that you can find,

a natural choice
for a divine being,

the very symbol of movement.

Getting the first time
on a horseback here,

and being able to just feel
the speed,

and the distance you can cover,

you can see
the whole possibility

of exchanging knowledge,

understanding the world
you are in.

It's a game-changer right?

It's a game-changer
in human history.

For nearly 6,000 years,

horses have been the
human race's special companion,

our extra muscle,

our overland vehicles,

and symbols of power.

Horses gave us
the freedom to move,

and that freedom changed
the very nature of human life.

For all we puny humans lack,
horsepower made up for it.

It's hard to imagine
where we'd be,

what our world would look like,

without horses.

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