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ELLA AL-SHAMAHI:
Why are Homo sapiens

the only species of human

that has spread all the way
across the world?

To make that incredible journey,

we would have
traversed scorching deserts...

It's thought that there was
no rainfall

for years on end.

Overcome the challenges
of the jungle...

They developed this
bone-tipped arrows.

AL-SHAMAHI:
I've got in my hands
right now something

that was used 48,000 years ago.
Of course, of course.

AL-SHAMAHI:
And it was absolutely
revolutionary.

...and ultimately navigated
treacherous seas.

Because that would be an
expedition today,

let alone back then.

All while sharing the planet

with other
remarkable species of human.

We place this skeleton

as a new species.

It's, um,
it's giving me goosebumps.

But none would ever reach

as far as we did.

"Human: Journeys"--

right now on "NOVA."

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

AL-SHAMAHI:
Over 300,000 years ago,

Africa was
the cradle of humanity.

The place where humans evolved.

Including the first of
a new species,

Homo sapiens.

Our species.

From humble beginnings,
our growing culture

and connections helped us spread
across that great continent.

And then, we ventured outwards,

away from our home
and into the wider world.

Our ancestors did something,

which is actually remarkable.

From a beach
not unlike this one,

possibly quite close by...

they ventured out

into an open ocean,

with only an empty horizon
in front of them.

And after many days and nights
on the water,

they eventually came upon this
new landmass

that they would settle.

We call that landmass Australia.

It was a pivotal moment
in the history of our species.

But in so many ways,

it's not actually the
destination that's important,

it is everything it took,
all the challenges they had

to overcome to make it

so far away from where
they began in Africa.

We were not the first humans
to leave Africa.

Long before we evolved,
the ancestors of our cousins,

the Neanderthals, set out...

and Homo erectus,

one of the most ancient humans,

had made it deep into Asia.

But none had ever made
the voyage to Australia.

Every other species of human
reached a point,

and then they just stopped.

They faced a barrier
that they either could not

or would not pass.

But not us.

This is the story of how time
and again,

we took on perilous journeys.

How the last species
of human to evolve

took on environments
like no others had.

To become the only
global species of human.

That title
is ours and ours alone.

Our journeys out of Africa began

over 120,000 years ago.

But as our species spread,

we were blocked by
expanses of ocean on most sides.

One of the few places
we could go was east.

To the vast landmass
that today is made up

of Arabia and the Levant.

At this time,
one of the few gateways

out of Africa
to the rest of the world.

Of all the species
of human that have ever existed,

I think we, Homo sapiens,

are the explorer species.

We can't help it.
We have to wander.

It is in our want to travel.

And this place

was the landmass next door.

You could see it from Africa.
And look at it!

It is absolutely breathtaking.

But it's not exactly welcoming.

And so, the question is,
why did Homo sapiens come here?

We know they did.

Thanks to finds
across the entire region.

From Israel and Saudi Arabia
to the Gulf states...

and even beyond to
the fringes of Europe and Asia.

Which is hard to explain
when today,

these lands look just as much
of a barrier as any ocean.

I always say archaeology is
a bit like a jigsaw puzzle,

and you're just constantly
looking for pieces

of that puzzle to help
you get the full picture.

And this is one of those pieces.

This particular piece
is a copy of a tooth.

Now it's a single tooth,
which gives you an idea

of how large this animal
must have been,

because it's,
it's bigger than a brick.

It's, I mean, it's, it's
practically the size of my head.

It is the tooth
of an extinct elephant.

And it was found in Jordan.

And we also have hippo fossils
from the Saudi Desert.

Now, hippos and elephants

do not belong in this
landscape-- look around.

Where's the water?

Hippos actually need
standing bodies of water,

and they need greenery.

And that's the thing
about some fossils.

They tell us

about what a landscape
used to look like.

Because these
do not belong here.

These finds point
to a very different Arabia.

One that,
if you know where to look,

you can see hints of
to this day.

If you look over there,

it almost looks like a mirage,

that white and silver
on the landscape.

So that used to be a lake,

and the white and silver is
actually salt

and gypsum that was left behind
when the water evaporated.

And scientists are really
interested

in not just aging them,
but also working out these

ancient water systems,
these extinct water systems.

And so,
one of the ways they do this

is by just getting
on the ground and walking

these beautiful but
incredibly intense landscapes,

looking at maps,
looking at satellite images.

And this is the result
of some of that work.

Now, if you look here,

this is a map of the region
just slightly north

of here, so, this is Saudi,
which is to our east,

and that there
is the Sinai of Egypt.

You can see it's basically
shades of beige and gray.

Now, look.

So, this is
about 125,000 years ago.

Water litters this landscape,
I mean,

you can see
the veins just running through.

There is no way that this land
would not have been green.

There are paleo lakes and paleo
rivers absolutely everywhere.

And this is this region

as we have never known it.

Now, remember,

this was a world
without borders,

and this was a land of plenty

within easy reach.

And so, why wouldn't
Homo sapiens have come here?

But what they didn't know,

what they couldn't have known,

is that this region
would be a trap.

The green days of Arabia
were numbered.

The desert was on the march.

Subtle variations
in the orbit of the Earth

caused the climate to change.

Within as little
as a few hundred years,

the rains vanished.

Starving this
entire region of water...

...leaving humans
at the mercy of the desert.

If you set out to create
an environment

that was completely
and utterly hostile

to our biology,

you'd come up with this.

The heat is such a presence,
that I can feel it on my back.

The sun, even at this time
of the morning,

feels like
it's borderline torture.

And there is no water
as far as the eye can see,

there's nothing.

And back then, it would
have been so much worse.

It wasn't arid,
it's what we call hyper arid.

It's thought that there was
no rainfall for years on end.

And so, we go from seeing
multiple sites

where humans lived

in this region to nothing.

We seem to vanish
for thousands of years.

And this could so easily have
been the end of our journey.

Defeated by the harsh desert.

We think that some Homo sapiens

clung on in pockets
that we call refugia;

those are refuges
where the climate is milder.

But from all we can tell,
they would have been

few and far between,
and they effectively faded away.

And so,
for all intents and purposes,

Homo sapiens outside of Africa
had failed.

And what's interesting is

other species of human
had cracked the code

of living outside of Africa,
but not us.

And so how did this happen?

People like me, so many of you,

how did we become
the only species of human

who exists across the globe?

These brutal conditions

persisted for years on end.

Until finally,

there was another
subtle change in climate;

allowing conditions
to become less extreme.

And giving Homo sapiens
another chance.

Occasional, seasonal rains
returned.

Just enough to bring
precious water

back to the desert.

Now, the conditions here
did get better.

So, yes,
you had desert and sand dunes.

But you also
had lakes and rivers.

And that resulted

in us being able to exist
in this place,

but not just exist here.

From an oasis here
to a river and spring

system there, we were able

to actually leave
the Arabian Peninsula

and face the rest of the world.

As they did,
these new waves likely absorbed

any small pockets of
Homo sapiens that had held on.

And now, scientists studying
the genetic code

of people alive today,

believe this moment was
a pivotal point in our history.

Our DNA has the power

to tell stories about us.

But some of
them aren't just stories.

They're sagas.
And they're extraordinary.

And one of them is that
every single one of us

whose origins are
from outside of Africa

comes from a tiny population
of Homo sapiens.

We started in Africa from
multiple populations

across the continent.

But then only
a small group of us left.

Perhaps as few
as 10,000 individuals.

And so, all of us from outside
of Africa

come from this

minuscule population who went on

to populate not one,
not two continents, but five.

But our journey through
the desert

was only one
of a multitude of challenges

Homo sapiens would face
as we spread

across the globe.

And because
we were so few in number,

our very survival outside
of Africa

was far from certain.

As this tiny population grew
and spread...

it crashed into another
extreme environment.

One that had thwarted

other species of human.

A vast, green wall.

Beyond the desert,
our species found themselves

in the giant
landmass of Europe and Asia.

To their north,
lay high, cold mountains.

So many spread
eastwards and south,

down through what is now India.

Reaching modern day Sri Lanka,
at that time joined

to the mainland
by lower sea levels.

And dominated by expansive,
dense rainforests.

And while this may look
so much more

welcoming than the desert,
nothing could

be further from the truth.

These leeches are

absolutely everywhere.

And when I say everywhere,
I mean, one has just got me.

And there are creepy crawlies
absolutely everywhere,

including in our trousers.

And they are
actually quite irritating.

This place is
also full of mosquitoes.

We saw a viper,

and a cobra, and that's
the thing about this place.

It is difficult to exist in,
it's hot,

it's humid, it's oppressive,

and you have to constantly have
your wits about you.

This is one of the most

extreme environments
on the planet.

So much of what grows here
is poisonous to eat.

And there are few
large animals to provide meat.

Conditions are so difficult,

that as far as we can tell,

other species of human
that left Africa

never ventured past the fringes

of such formidable forests,

instead taking
alternative routes.

Being here is a bit
like stepping back in time.

Because about 50,000 years ago,

this place would've
basically looked the same.

This huge cave mouth

would have been here.

Only back then,
the rainforest would have been

unbroken, and it would have gone
on for kilometers

in every single direction.

And yet, somehow,

in this cave and two other caves
not far away,

we have found evidence

of our ancestors living here,

all the way back then,

in the heart of what would
have been a massive rainforest.

So, how were Homo sapiens

able to plunge into a place

no others had?

How did they find food,
particularly meat?

They did have the advantage

of bow and arrow technology,

which had arisen
thousands of years earlier.

But heavy, stone-tipped arrows
were not well-suited

to firing into the high canopy
of the rainforest.

Their solution was uncovered,

thanks to over
30 years of excavations

deep into the floor of this cave

and the two other similar caves.

Digs that reach all the way back

to 48,000 years ago,

when the pioneers of our species

first attempted to overcome the
challenges of this rainforest.

Starting with perhaps
one of the most important;

how to find enough meat
to sustain them.

So here, you can see a
monkey bone.

We can clearly
see that the "V" shape.

This 'V' shaped cut marks

only can produced by
the stone tools.

AL-SHAMAHI:
Yeah, so, this here,

that's where somebody
is cutting.
Yeah, yeah.

Yeah, they are cutting or
- skinning also can be possible.
- Yeah.

Whatever stuck with the bones,
they tried to remove.

AL-SHAMAHI:
It's funny because I think

butchery marks often need
to look at it

through a magnifying glass,
but not always.

And actually,
this one is quite clear.

And this is not the kind of
thing that you would

see if an animal killed it.

This is an indication

that this is killed by a human.

This is definitely
Homo sapiens.

AL-SHAMAHI:
And so, the question is,

how they killed them?

It is remarkable, Ella, because,

there are lots of trees,
very tall,

in second they can climb
up to the top,

so therefore, it is
very difficult to catch them.

The pre-historic people,
our ancestors,

should need to develop their own
technology,

to get them down.

So I would like to show you
some earliest,

which goes
back to 48,000 years old.

They developed this
bone point technology

and they made
bone-tipped arrows.

They identified the monkey bones
are really special

to make arrowheads,

because those are light
in weight,

to hunt these
fast-moving animal.

If you use a stone point,
the arrow is heavier.

So here you can see,
it is a little bit chipped

because it's hit,
it contacted something.

Right.
So that is why

at the end,
it's very small...

AL-SHAMAHI:
So that chip mark there,

shows us that
it was actually used.

Yes.

Uh, it's, I mean,
it's amazing because

this is obviously,
I've got in my hands

right now something
that was used 48,000 years ago.
Of course, of course.

And it was absolutely
revolutionary.

These bone points are only
the tips

of the full arrowheads.

Many are chipped
from actually hitting prey.

And each one
would have been attached

to the end of a long,
wooden arrow.

These hunters didn't
invent a brand-new technology.

They adapted an old one.

These are some of
the earliest examples

of bow and arrows
found outside of Africa.

Enabling Homo sapiens

to hunt with exceptional skill
and efficiency...

...within the forest.

But we know
that the humans living here

were doing
more than just surviving.

Oshan Wedage
and the team also found beads;

many fashioned from shells.

Shells perhaps bought in

as trade from groups

living on the coast.

A constant struggle to survive.

Doesn't leave much time for
making works of art.

Suggesting a long established

and successful community

existed here.

And for that,

to turn this place into
a true home,

would take something fundamental

to our species.

This is...

...a replica.

Of a tool that was found in the
caves in this area

dated from about
40,000 years ago.

It is a monkey tooth,

specifically a canine,
but that's been modified.

If you look here,
it's been cut into

to create a much sharper point.

And the reason for that

is that it's

a tool used for puncturing.

Oh, it's not easy.

All right, look, I finally
managed to make a hole.

And once you make a hole,
you can then use plant fiber,

animal sinew as a string

and start stringing
animal skins,

animal hide together
and create clothes.

But actually, in so many ways,

that's not the most interesting
thing about this tool,

because for me,
the most interesting thing

is what this tells us
about the minds of the people

who have made it.

Because you have
to be taught how to use it.

You have to
be taught how to make it.

So, it actually tells us
something much deeper.

Throughout the years, humans
made this cave their home,

countless elder generations

would have taught children

these techniques.

Something we still do
to this day;

a communal passing on
of knowledge

that is key to our ability

to master so many
different environments.

That engagement,

constant engagement,
turns every generation

of children into a step in
the evolution of knowledge.

And for us, Homo sapiens,

that's probably
what adaptation is:

the evolution of knowledge.

Because it's what turns a
simple projectile like an arrow

into a weapon fine-tuned, honed,

and specialized for the
rainforest.

And that constant
innovation unlocks resources.

And it's this ongoing evolution

of tools and techniques...

...that has allowed our species,
time and again,

to live and thrive...

...even in extreme environments.

That is the strength of our
species,

that we were opening up
so many new environments,

places that previously
other species saw

as impenetrable,
as too difficult.

We thought of having
long-term potential

and we were able
to expand in number.

We were able
to then adapt to it.

And as we grew,
some people could decide

to move on to yet
another environment.

We were becoming a species
with truly global potential.

It was that ability to take on

so many different,
challenging environments

that carried us
through so much of the world.

By now,
to the fringes of Europe...

...into the cold expanses
of northern Asia.

And, within only a few thousand
years of leaving Africa,

deep into Southeast Asia.

Where today there
are sweeping stretches

of tropical waters,
back then much lower sea levels

created a vast landmass
known as Sundaland.

Eventually, our wandering feet

brought us to its outer edge.

Beyond lay an ocean...

...dotted with isolated islands.

Even all those years ago,

the ocean could not
stop the spread of our species.

Homo sapiens reached
these remote islands,

thanks to an ancient technology
that we

quickly came to master.

This is a tuna fish bone.

This particular one
happens to be quite fresh.

It's a few days old.

But we have actually found
tuna fish bones

on an archaeological site on
these islands

that dates
back to over 40,000 years.

Tuna swim in open waters.

And that means...

...that over 40,000 years ago,
they were fashioning some kind

of vessel and going out
into the open waters

and coming back
again and again and again.

We can't be sure what form
these vessels took

since no evidence survives,

but they were probably simple
rafts made from available wood.

And they did more
than just help us fish.

There is a very interesting
archaeological site

on one of
the neighboring islands that has

this one layer that is just
filled with artifacts

belonging to Homo sapiens,

but the layer just before it,

immediately preceding it,

is empty and barren
of those same artifacts.

So almost suggests
that our ancestors just kind of

turned up overnight and spread

rapidly through these islands
in large numbers,

just because of the sheer volume
of artifacts within that layer.

And none of that
would really be possible

unless you were skilled enough
to build robust craft,

you were skilled enough
to navigate treacherous waters.

But in a truly unexpected twist,

Homo sapiens were not the
first humans to reach Flores.

Somehow,
someone made it here before us.

We know, thanks to
an incredible discovery

made in a cave
in the west of the island.

For over 20 years,

a team of Indonesian and
international archaeologists

has been excavating this cave.

They were searching
for evidence of the spread

of Homo sapiens
through the islands.

Instead, they found something
completely unexpected...

...a strange skeleton from
at least 70,000 years ago...

...so long before our species

reached this far from Africa.

I think the first thing
obviously that strikes you

when you see her
is that she's very short.

Yeah, yeah, very short.

Um, what are we talking,
one meter?

Yeah, the skeleton
is about a meter

and six centimeters tall.

Right, so, about
three and a half feet?

Yeah, just like all of our team,

when saw this
for the first time,

we thought that this
belonged in a child.

But then after we able to,
to clean up all the dirt,

you can see,

all the, the, the molars
have already erupted.

It's got wisdom teeth.
Yes, yes.

There is already
permanent teeth.

Yeah, I mean, the molars are,
the adult molars are there.

Yeah, already there.
Three of them. Yeah.

As soon as you look closely,
this is 100% an adult.

Yeah, yeah.

AL-SHAMAHI:
An adult,
but the size of a child.

And that was
only the first surprise.

The legs,
they're quite short.

Yeah.

The leg is only
slightly longer than,

than the, the arm here.

AL-SHAMAHI:
Whereas with us...

Yeah, with us, it's different.

Our legs are really long
compared to our arms.

Compared to upper limb,
I think.

And also, if you have a
look on the feet...

Yeah.
Yeah, the feet is about

70% of the length
of the femur.

Which is huge...
Is huge, yes.

...because on me,
that would be...
Yeah.

About that length.
Yeah, it's true.

Because so many unique features

not seen in other species,

we place this skeleton
as a new species.

And we named

the skeleton Homo floresiensis.

AL-SHAMAHI:
This new species of human
was a revelation.

Named Homo floresiensis
after the island,

they quickly became known
to many as the Hobbits,

after the heroes from the
"Lord of the Rings" books,

who were also small as adults.

They likely arrived
entirely by chance,

initially perhaps a few
individuals

swept here on driftwood
from the islands to the north,

more than 700,000 years ago.

They eventually became
a unique species

seemingly with a mix of modern

and more ancient
characteristics.

Now, we can see obviously

the brain is small,
but how small are we talking?

Only one third of the

modern humans' brain size,
I think,

almost similar to
an adult chimp.

That... how incredible.
That's right.

We discover the skeleton

with stone artifact here.

AL-SHAMAHI:
Such a small brain

and yet they had stone tools.

Yes, indeed.

AL-SHAMAHI:
Before this,
scientists assumed

that a human
with such a small brain

could never have developed
such tools.

One theory is that they were
initially a much larger species,

before the long isolation
on Flores caused them to shrink,

a process known
as island dwarfism,

where large animals get
smaller due to fewer resources.

At the same time, some small
animals actually get bigger,

due to a lack of predators.

We found a giant rat,

up to about three kilos.

We also found
elephant-like creatures,

called stegodon,

as big as a water buffalo.
This is smaller one.

AL-SHAMAHI:
So stegodons generally are not
the size

of water buffalos...

Exactly, yeah.

AL-SHAMAHI:
But on this island, they're the
size of a water buffalo.

And then on this island,

you've got humans
that are a meter tall.

Yeah, they're small.

What you're describing there

is a species that

has been shaped
by this island,

has been shaped by
the environment on this island.

And the result is this.

Long isolation allowed evolution

to tailor the Hobbit
to this environment.

Their long arms
compared to short legs,

a response
to perhaps the steep terrain,

or the lack of predators
on the island to run away from.

Physical adaptations that, along
with those simple stone tools,

helped them survive here for
hundreds of thousands of years.

You can see
it's like layers of cake.
Yes.

AL-SHAMAHI:
So, every period
has left a layer.

So, this is like
a snapshot in time

telling us a lot about
different periods.

Yeah, there is a series
of volcano eruption.

Eight volcanic tephras.

AL-SHAMAHI:
That's basically
flow from volcanic eruption.

Yeah.

This tephra is very important
at Liang Bua

because there,
this tephra, called Tephra 3,

this dated
to about 50,000 years ago.

AL-SHAMAHI:Mm-hmm.

And all Homo floresiensis
skeletal remains

derive from below this tephra.
Right.

And then, Tephra 5,

the gray and pinkish color.
Yeah.

And when we dated
this flow stone,

including charcoal, date back
about 46,000 years ago.

And just above all this layers,

we found several
element of modern humans.

So Homo sapiens.
Homo sapiens.

So that there is
a boundaries between

floresiensis and modern humans.

The massive
pyroclastic flow here.

AL-SHAMAHI:
That's really significant.

So, the pyroclastic flow
is when you have the gas

and material that comes from
a volcanic eruption,

and really, I mean, that would
just be quite destructive.
Yeah.

But we still don't
have the fixed evidence

that this volcanic eruption

causes the extinction
of the Homo floresiensis.

AL-SHAMAHI:
We don't think that
final eruption

alone caused
the extinction of the Hobbit.

It would have been
a catastrophic event

here at the cave,
but we don't know how

it affected
the rest of the island.

What we do know
is that this shows

the time of the Hobbit here
was coming to an end.

It is wonderful to imagine

what this place was like
before all of this.

Thousands of years
before our ancestors,

you had these miniature
elephant-like creatures

who wandered open grasslands.

You had actual dragons,

the Komodo dragons,
who still exist.

And then giant marabou storks,
storks, they're all carnivorous,

that were my height
or taller and could fly.

It was like a fantasy island,
and amongst all of it,

there were these humans
who were tiny,

who came up to about my hip.

And those Hobbits lived here
on this island

for a staggering length of time,

potentially for
more than 700,000 years,

that's longer than
our species has existed at all.

And yet, there is this twist
because so far,

we have found no evidence
of them past these shores.

Their whole story plays out
only on this island of Flores.

Our own species,
in just a fraction of that time,

was able to spread across
a huge portion of the globe.

Around 50,000 years ago,
the climate here

became warmer and drier,
changing the environment.

At the same time, those violent
volcanic eruptions also struck.

Whatever the reason,
it meant that Homo floresiensis

faced not just change,

but rapid change.

That meant
that their physiology,

their physical
adaptations that for so long

had been a benefit,
were now a trap.

They were being left behind
because it's actually

incredibly difficult
to rapidly evolve your way out

of a sudden crisis.

And they couldn't behaviorally
adapt to this change either,

nor could they, say, escape
and move to another island.

And so,
these wonderful, fantastic

relatives of ours
vanished forever.

And in their place,
Homo sapiens appeared,

making this island,
like so many places, their home.

So far, we've found no evidence

that our two species overlapped.

But many anthropologists
suspect that the final factor

in the Hobbits' extinction
was likely our sudden arrival.

The Hobbits
simply couldn't compete

with this highly adaptable
newcomer.

A species able to change its
behavior to suit almost

any environment and condition.

The very characteristics driving

our continuing
spread across the globe.

As we spread further
and further away from Africa,

entering into brand new
environments

that we had never experienced
before...

...we're not just surviving
in these places,

we're actually
setting down roots

and roots that would last us
till this very day.

There was one
last part of this journey to go.

We set out on a path no other
human species had traveled.

Perhaps following
tantalizing hints

that there was more land
to explore.

Clouds on the horizon...

...returning flights of birds...

...or maybe something
much more instinctive.

That inspired,
we think, dozens of families...

...to strike out on a voyage
that would carry them

to a new continent...

...Australia.

Now, these were people

who were comfortable
on the water.

They were going
from island to island,

but Australia
was something different.

We're talking about a journey
that was

up to a hundred kilometers,
60 miles.

That's days and nights
on the open ocean,

probably in something
as basic as a raft that was

perhaps being propelled
and steered with just paddles.

Launching out into that
hostile and expansive ocean...

...that would be
an expedition today,

let alone back then.

When I think about

the risk involved,

when I think about
the emptiness,

it is just
absolutely astonishing.

The islands of Indonesia

were another waypoint
in our ongoing journey.

Our unique adaptability

that helped us cross
the harsh desert

and break through
the barrier of the rainforest...

...now carried us
across the sea...

...to Australia,

nearly 9,000 miles
from where we began.

Leaving the question,
what kept driving us on?

Ultimately inspiring us to
take on the dangers

of the open ocean.

It's true that there will often
have been a push,

the simple need
to find new resources

for our expanding population.

But I would argue

that that is not
the full explanation.

But this is the most
intangible part of the story.

See, these people, in
my opinion, were just like us,

so they had the same fears
and hopes for their families.

We are clearly
the explorer species.

I think that is beyond a doubt.

And as a result, we've been able
to take on things

that seem absolutely impossible.

In that desire to understand
what was out there,

in the thrill and excitement
of understanding the unknown

and the willingness
to take risk,

to know it,
see, wanderlust, creativity,

and the imagination
required to put yourself

in a different place,
into a different future

and world, I think
that is fundamentally us.