Original subtitles

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.

This story begins over 120,000 years ago.

As our species spreads beyond the borders of Africa...

..they're blocked by expanses of oceans on most sides.

One of the few places they can go is 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 wont 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.

Nothing about this place says home.

And so, the question is,

why did Homo sapiens come here?

We know they did,

thanks to finds 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 bigger than a brick. It's...

I mean, 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 ageing 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 grey.

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've 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've 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...

..they would crash into another extreme environment.

One that had defeated all other species of human -

a vast green wall.

Once 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 the Indian subcontinent,

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 so difficult

that, as far as we can tell,

no other species of human

ever made it past the fringes of these rainforests.

Being here is a bit like stepping back in time,

because about 50,000 years ago,

this place would have basically looked the same.

This huge cave mouth would've been here.

Only back then, the rainforest would've been unbroken,

and it would've gone on for kilometres

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've 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 less 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 - and the two other two 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 one of the most difficult -

how to find enough meat to sustain them.

Yeah. So, this here, that's where somebody is cutting?

Yeah, yeah.

Yeah.

Yeah. 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.

And so the question is how they killed them.

Right.

So, that chip mark there...

..shows us that it was actually used. Yes.

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 and the team also found beads fashioned from shells.

Perhaps brought in through 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've finally managed to make a hole.

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

animal sinew, as a string, 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 a bow and arrow

into a weapon fine-tuned, honed, and specialised for the rainforest.

And that constant innovation unlocks resources that were

completely out of reach to other species of human.

Resources like the rainforest.

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 saw as 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 would 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.

Lower sea levels had created a single region known as Sunda...

..where today there are sweeping stretches of tropical waters.

Our wandering feet brought us to its outer edge.

Beyond lay an ocean, dotted with isolated islands.

There are these places that you turn up to and you think,

"I'm on the edge of the world."

They are incredibly remote and isolated,

and this is one of those places.

And it's been like this since the very beginning,

since its formation,

because it's been surrounded by this very deep sea,

which makes what was found here even more intriguing,

because a mind-boggling, completely unexpected human history

plays out here over hundreds of thousands of years.

Even all those years ago,

the ocean could not stop the spread of our species.

We reached these remote islands, thanks to a technology that,

as far as we can tell, we are the only humans 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.

But tuna swim in open waters, and that means that our ancestors,

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 neighbouring islands that has this one layer

that is just filled with artefacts belonging to Homo sapiens.

But the layer just before it,

immediately preceding it, is empty and barren of those same artefacts.

So it 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 artefacts 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 surprising twist, we were not the first to reach Flores.

Somehow, someone made it here before us.

Sometimes in this job, you get to fulfil a lifelong dream,

and one of them is about to happen.

See, there's this cave in palaeoanthropology that isn't

just fascinating, it's basically explosive.

It started in 1950,

with this one priest called Father Theodor Verhoeven.

Now, back in the day, it was actually quite common

for priests and missionaries to also dabble in archaeology,

so he was out here on Flores looking for archaeological sites.

And in talking to locals,

he got told about this one cave that had potential.

He turned up, it was actually being used as an amateur school,

but just below the surface, he did actually find archaeology.

Actually, it was stone tools belonging to ancient humans.

Now, that in of itself is huge, it's really significant,

but it would take another half a century before we understood

just how important this cave was.

For over 20 years, a joint Indonesian and international

team of archaeologists has been excavating these caves.

They had been 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.

Um, what are we talking, one metre?

Right, so about three and a half feet? Yeah.

It's got wisdom teeth. Yes.

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

Yeah, yeah, yeah.

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

Yeah. Yeah.

An adult, but the size of a child.

And that was only the first surprise.

The legs, they're quite short. Yeah.

Whereas, with us...

Our legs are really long...

..compared to arms.

Yeah.

Yup.

Which is huge... Is huge, yes.

..because on me that would be about that length.

I mean, this is one of those moments in the history of the field

where I just wish I had been there.

I know she's a replica, but she's a replica of the real thing,

and, yeah, it's...

It's giving me goose bumps.

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, who were also small as adults.

It's likely they arrived entirely by chance. Perhaps a few

individuals swept here on driftwood from the islands to the north...

..more than 700,000 years ago.

Eventually becoming 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?

That... That's right. How incredible.

Such a small brain, and yet they had stone tools.

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.

So Stegodons generally are not the size of water buffaloes.

Exactly, yeah. But on this island...

It's big one. ..they're the size of a water buffalo. Yeah.

And then on this island, you've got humans that are a metre tall.

Yeah, that 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.

So every period has left a layer.

So this is like a snapshot in time, telling us

a lot about different periods.

That's basically flow from volcanic eruption?

Yeah.

Mm-hm.

Right.

Right.

So Homo sapiens.

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.

We don't think that that final eruption alone caused

the extinction of the hobbits.

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 hobbits here

was coming to an end.

So you're looking at actually quite a different world down there,

to up there. Yeah. Exactly, yes, exactly.

This tiny island has been home to two species of human.

One remains to this day.

One vanished long ago.

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 that were 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,

longer than we've existed as a species.

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 behaviourally 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 for many, the final factor in the hobbit's extinction

is likely our sudden arrival.

The hobbit simply couldn't compete

with this highly adaptable newcomer...

..a species able to change its behaviour

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 travelled...

..perhaps following tantalising 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 100km,

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 deserts...

..and break through the barrier of the rainforest...

..now carried us practically to the ends of the Earth.

To Australia, around 9,000 miles from where we began.

Which does beg 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,

that 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 have 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.

We chart the spread of Homo sapiens into the expanses of Europe

as our species struggles to survive in the grip of a cruel Ice Age

and comes face-to-face with another sophisticated species of human...

..the Neanderthals, who had long mastered life in these cold lands.

In this episode, we filmed at a place I've long dreamt of visiting,

one of the most important human archaeological sites of all,

Liang Bua cave...

..where scientists are still trying to solve the many mysteries

surrounding the hobbits, the ancient humans that lived here.

In 2004, their discovery sent shock waves through

the scientific community.

So, the moment the paper's dropped, it was massive.

It was all over the news.

It was all over the internet.

Everyone was talking about this tiny,

unexpected hobbit from Indonesia.

Paige has known Thomas and the team since 2017,

documenting their research.

Like many scientific breakthroughs,

the initial discovery created intense controversy.

The conferences got extremely heated.

Sometimes there would be hobbit sessions where within the same

session, you would have a few talks would be sort of pro hobbit -

so, "This is a new species, this is really exciting,

this is changing a lot of what we thought we knew

about human evolution" -

and then in the same session,

you would have people that are saying,

"This is the biggest mistake

"that human evolution scientists have ever made."

Many argued that this was not a new species,

but a Homo sapiens suffering from an illness that caused its small

physical features and brain size.

Eventually that was discounted, and Homo floresiensis was recognised

as a new species of human - raising, if anything, even more questions.

We still don't know, for example,

where they came from or who they're closely related to.

So that question of the origins of Homo floresiensis is still,

I would say, almost completely an open one.

It's possible they evolved from another ancient

species of human, such as Homo erectus,

which we know was in the area just over a million years ago.

Perhaps carried to the island by chance,

and then shrunk down over many years of isolation.

But there is an even more controversial idea.

If you look really hard at a lot of the characteristics,

particularly below the cranium...

..you see that this is a creature

that looks a lot more like some of our really ancient ancestors,

more than two million years old, in Africa.

And so maybe there was an exodus out of Africa a million years

before we thought there was.

This current dig might reveal the answer.

With help from the Max Planck Institute in Germany,

researchers are trying to collect fragments of hobbit DNA.

Ancient DNA is really helpful at really laying out

relationships for us between different species across time.

And so, because of the way that mutations accumulate over time,

it allows us to kind of work backwards

and trace back when some of those lineages would have split.

Homo floresiensis, and whoever their closest ancestor is,

which is not a question we can answer until we kind of

have some of that information.

The problem is successfully finding hobbit DNA will not be easy.

Normally it would be impossible to recover DNA from a situation

where it's this hot.

It's just too difficult.

DNA degrades really rapidly, and other things move in

and muddy up the signal, like bacteria and other things.

But in this cave in particular,

it is at a slightly higher altitude than a lot of Indonesia is,

it's right up in the mountains,

and so it is a little bit cooler than most equatorial areas.

And so there is a little bit of hope that we might be able to

get a little bit of a signal from the species.

If successful, we might finally solve the mystery of the hobbit.

Whatever happens, Homo floresiensis will remain one of the most

important and unexpected discoveries of recent history.