[calm music]
[narrator] In every corner of the world today are humans.
Seven billion of us.
How did we come to so dominant our planet?
It's one of science's greatest mysteries.
Amazing new evidence suggests it began in Africa
when a tiny group of people left the continent
on an incredible journey.
[lively music]
Using bones, stones, and genes,
we'll uncover the trails their descendants left
across the world
and find out how their journeys transformed our species
into the people we are today.
We begin by going in search of the first humans.
We discover how we survived
in our dangerous homeland of prehistoric Africa,
and search for the route we took out of Africa
on the way to colonizing the whole world.
[ominous music]
[African tribal music]
[narrator] Where do we all come from?
Where does our human journey begin?
It seems that it's here
in the Great Rift Valley of East Africa
that our species has its homeland.
[children singing in native language]
In all likelihood, we have been living here
for longer than anywhere else on earth.
[singing in native language]
The best evidence for this was discovered in 1967.
Richard Leakey,
son of legendary fossil hunters Mary and Lewis
was following in his parents' footsteps
searching for humankind's origins.
In the first place, I think the perspective that we have
from our prehistoric past is relevant,
but perhaps more importantly,
it's also possible to look into our past
and see why it was that we succeeded
whether other animals failed.
[zooming]
[narrator]Working with a team of scientists,
Leakey set off to explore a remote area
on the far side of the Omo River in southern Ethiopia.
But just reaching the location was an enormous challenge.
And after months of planning they made it
to the banks of the great river,
only to be faced with disaster.
[ominous music]
A huge crocodile attacked their boat,
the crew were lucky to escape with their lives.
[tense music]
And even once they'd managed to make the crossing
their luck didn't improve.
The site was looking fruitless.
Until one of the group spotted some fragments of bone
sticking out of the sand.
When the pieces were painstakingly put together
they revealed this... a human skull.
And in 2005 new dating techniques revealed its age,
around 195,000 years old.
This is the oldest member of our species,
Homo sapiens, ever found.
[uplifting music]
[chanting in native language]
It's good evidence that this region of East Africa
was our first homeland.
[chanting in native language]
But who are we?
And how did we get here?
[gibbering]
The very first human creatures evolved much earlier
than the people of the Omo valley,
around four million years ago.
They were much more ape-like than us.
A series of different species of human then evolved.
They had gradually increased brain size
and were better adapted to life in the African Savannah.
We are the most recent in the line,
Homo sapiens, or modern humans.
[calm music]
The evidence is very fragmented,
but it seems likely our most recent ancestor
is an ancient human creature like this.
[crackling]
In 1921, archaeologists found this skull in a mine pit
in Kawbe in Zambia.
It's a prime example of Homo heidelbergensis.
So what's the difference between him and us?
By comparing him to Herto man,
a well-preserved Homo sapiens skull,
we can see what changed through time.
This is...
a fossil form of modern Homo sapien,
a Herto skull and this one is Kabwe.
What you see, when you see these two
you can see it clearly, they're really different.
[Berhane] As you can see,
Kabwe has lots of primitive features.
The way it's compared to a modern Homo sapien.
Kabwe doesn't have a forehead,
which is typical of primitive forms.
[Berhane] Modern Homo sapiens, that is us,
has a forehead,
and when you see the face,
Kabwe's face jets out more.
[Berhane] It has heavy browage
which you don't see in the modern Homo sapien.
[narrator] When reconstructed
homo heidelbergensis looks similar to us,
apart from his long low head and heavy brow.
But these ancient humans completely died out,
while our species flourished and spread across the planet.
So what was so special about us?
[light music]
When we think about what makes us stand out
from other animals today
we might say art, music, language, religion,
the ability to plan, or to love perhaps.
But has this always been the case?
Did the very first humans share these characteristics with us?
Not all scientists think so.
But recently an astonishing discovery was made
that gives us a clue what our ancestors were really like.
[light music]
The site of the find is 5,000 kilometers
from where the Omo skull was discovered in South Africa.
[waves splashing]
[crashing]
Today, Pinnacle Point is a playground for the rich,
but what lies below the manicured golf course
has seriously changed our understanding
of the behavior of our early ancestors.
[chanting in native language]
And it's all down to this cave.
[chanting in native language]
Because people were here 165,000 years ago,
people apparently just like us.
It's one of the earliest places we're known to have lived.
Well, this cave I know from my experience excavating here
the setting is obviously beautiful,
you can't have a better place to work,
um, but climate-wise it's very comfortable,
it can be stormy and wet outside and in here you're warm and dry.
Um, it's generally protected from the wind.
It's a, it's a good place to live.
[waves splashing]
[narrator]But it's what these people left behind
that suggests they already had
what we regard as typically human qualities.
These types of tools are, are very typical
of what we find in this cave,
um, this is a quart side blade, and this is a quart side point
and alongside these in the oldest deposits,
um, we also find these much smaller bladelets.
They're obviously very small blades
and because of their small size,
it's unlikely that these would have been,
uh, handheld tools for, for cutting.
Um, it's very likely that these represent
some of the earlier stone tools,
uh, that were set into a handle.
[narrator] Tools this complex are typical of our species.
They can be used for cutting wood or plants, butchering meat
and hunting.
[Kyle] These barbs that prevent the tip from pulling out,
the wounds that weapons like these can inflict
creates a, a blood trail that can be tracked.
I think that would be, uh, a pretty effective tool.
[narrator] And from what the archaeologists
are finding in this cave
it seems our ancestors put their tools to good use.
We really find a whole range of food remains, um,
we're talking about land animals,
we're talking about anything from buffalo
to, uh, dune mole rat, to tortoise,
um, so people were at this time very accomplished hunters.
[narrator] But despite their skill
this wasn't an idyllic lifestyle.
Our ancestors weren't the only hunters
living in these caves.
[calm music]
[Kyle] It would not have been a simple trip
to the grocery store to get their food.
-[hyena screams] -[lion grunts]
Very near to this site there's a carnivore den
that we've excavated,
um, it has some extremely large lion teeth in it
so by consequence the, the hyenas that gathered
that lion must have been a pretty large size too.
-[hyena screams] -[lion growls]
[narrator] So with dangerous predators as neighbors,
how did we survive?
A clue is in the floor of the cave at Pinnacle Point.
It's littered with ancient mussel shells.
This is the earliest evidence of humans eating sea food,
and may have given our species a huge advantage,
because by gathering food from the sea
our ancestors didn't have to rely
on outcompeting the lions and hyenas.
And this also reveals something else about us,
something that would really set us apart.
[Kyle] Most of the shellfish that they're collecting
you really have to be able to pay attention to tides
and you have to, to plan your, your visits down to the ocean.
It's, it's not usually the case where you can just walk down
and collect something off the rocks,
you have to pay very careful attention
to both the spring and neap tides
in order not to be swept away.
[narrator] This ability to plan ahead
gave our species an enormous head start.
But there's another discovery at Pinnacle Point
that makes the people who lived here
seem even more like us.
Ochre, a natural pigment often used for creating art.
This piece has been deliberately marked or engraved.
It may have been used to draw on the cave walls
or for body painting.
This suggests the people living here
had high levels of communication,
and perhaps even language.
In the time period we're looking at,
you see technology that's, that's advanced enough
and requires enough planning
that the technology would need to be taught.
And it's, it's probably not something
that could just be done visually,
um, it would need to be done in words and expressed.
So, um, I think it's that,
it's that transmission of knowledge
from one generation to the next, I think we see evidence of that,
it really, really couldn't have happened without speech.
[narrator] Language allowed humans to organize their society
in a way no other creature was capable of.
We can never know what they said to each other,
but we might be able to get just a hint
of what it sounded like.
Two thousand kilometers north of Pinnacle Point
lies a vast land of semi desert.
[lively music]
[chirping]
[African tribal music]
[indistinct chatter]
This is the home of the San Bushmen of the Kalahari.
And it's in them we might find a hint
of the language of our forefathers.
[speaking in native language]
The language they're speaking is known as a click language.
[speaking in native language]
My name is Toma, me T-O Toma.
We have four clicks in our language,
I mean the first one is ka-ka...
[Bertus] Ka. Ka.
Ka.
And the second one is ka...
Ka.
Ka-ka.
And the third one is tut-tut-ka.
Ka.
And the fourth one is ka-ka, ka.
[clicks tongue] [Bertus] Ka-ka.
[speaking in native language]
[narrator] There are many different
- click languages in Africa -[baby coos]
but 3,000 kilometers away in Tanzania
there's a tribe who speak a click language
so similar to the one spoken by the Namibian Bushmen
that some scientists think they're linked.
[speaking in native language]
[chanting in native language]
This is intriguing,
because these two groups of people
may not have been in contact for over 100,000 years.
One explanation is that the clicks existed
before these two tribes went their separate ways
and are therefore an ancient element
in human language.
[speaking in native language]
[baby cries]
[speaking in native language]
And it's possible that such a language
may have given us a special advantage.
When Bushmen hunt
they sometimes do something called devoicing.
[indistinct chatter]
They stop using vowels
and communicate only through their clicks.
The idea is to make it hard for their prey to detect them.
[speaking in native language]
But the Bushmen can show us something else
about what may have made our species so successful.
By looking at how they hunt,
we can learn how our bodies
enabled us to become supreme predators.
[lively music]
The Bushmen use a very distinct hunting technique.
It's called persistence hunting
and is perhaps the most ancient method of catching prey.
Their strategy is to track their target
and then run it down
until it collapses with exhaustion.
Our species may not be able to outsprint an antelope,
but we can outrun one over a long distance.
So how do we do it?
[rustling]
Our first advantage is that we have lost all our fur,
and we sweat from glands all over our bodies,
allowing us to cool down
much more efficiently than most animals.
This is crucial, especially during persistence hunting,
because most of our prey need to pant to cool down,
which they can't do whilst running fast.
So they are forced to stop,
allowing the hunters to catch them.
[calm music]
And our efficient cooling system
also means we can hunt in the day
when the other big predators,
the lions and the leopards, tend to stay away.
[growls]
They normally hunt at night to avoid overheating.
And it's not just our ability to keep cool
that makes us so good at distance running.
We have long legs for the size of our bodies.
And we have evolved a brilliant system of springs
in the leg and foot
which store and release energy when we're running.
And there's one muscle that's fundamental
to our ability to run for a long time.
The gluteus maximus, or buttocks.
It's this muscle that helps stabilize our bodies
when we're running.
These physical adaptations
combined with our ability to communicate
and our advanced technologies
give us a hint of what made our ancestors so successful.
From East Africa to the Cape in the South.
But if this is our homeland,
when and how did we leave Africa?
[rustling]
Until recently, all we had to go on
was a sparse archaeological record,
but new discoveries
in one of the most exciting fields of science
is unlocking the mystery,
and amazingly the clues lie within each and every one of us.
[light music]
Buried in our bodies
is an indelible record of our past,
a story of our ancestors.
Can this tell us how we left Africa?
The secret lies in our DNA.
Scientists are able to take samples
of a special type of DNA that we all carry within us.
It's called mitochondrial DNA
and it's passed down from mothers to their children.
But once in a while,
something goes wrong with the copying process
producing a random harmless mutation.
These rare mutations enable scientists
to build a global family tree.
The tree is thickest at the bottom.
This represents our roots in Africa
where our species first emerged.
And the branches at the top of the tree represent
the DNA found in people
throughout the rest of the world.
Every single person outside of Africa
can be placed on these branches.
And in Cape Town, South Africa,
is a man who spends his life working with DNA.
[splashing]
Africa's crucially important
because as you can see on this tree
the branches in Africa are the thickest and the densest
and the thickest part of the trunk
is where you look for the origins of humanity,
and that trunk and the root is right here in Africa.
[Ramesak] So the mother of all of humanity,
a single African eve so to speak, is right here.
[narrator] Extraordinary as it sounds,
analysis of the data indicates that every person alive today
shares a single common ancestor,
a woman who lived in Africa over 100,000 years ago.
She is right at the bottom of the tree.
But there's an even more surprising revelation.
When we put all of this information together
mapping people from all parts of the world,
what we are able to see is that there was probably
a single migration route out of Africa
and then out towards Asia and Europe.
[narrator] Just one thin branch of the tree
connects Africans to everyone else,
which suggests amazingly that everyone outside of Africa
descends from just one group who left the continent.
And scientists can even estimate the size of this group.
It may have been no more than a few hundred people strong.
The rest of the world was populated
by descendants of this tiny pioneering group.
What's more if it was just one group
it suggests they took only one route out of the continent.
So which way did they go?
[African tribal music]
We can see from a map of Africa that there was no easy way out.
The people of the sub-Sahara
were essentially living on an island,
cut off by oceans to the south, east, and west,
and by an impassable desert to the north.
The Sahara stretches the width of the continent,
covering nine million square kilometers,
it spans 11 countries.
But surprisingly,
a discovery on the other side of the desert in Israel
promises to reveal vital clues
about the human journey out of Africa.
[chanting in native language]
The discovery was made in the 1930's
by the first female professor at Cambridge University.
[chanting in native language]
And what she found was staggering.
[chanting in native language]
[calm music]
Archaeologist Dorothy Garrod was leading an excavation
on the slopes of Mount Carmel.
Outside a cave known as Skhul,
they uncovered stone tools similar to those found
at Pinnacle Point in South Africa.
But even greater treasures were found
when they dug one and a half meters down
almost to the bedrock outside the caves.
The remains of ten human skeletons.
After painstakingly chiseling out the blocks
in which the remains were entombed,
Garrod's team encased them in plaster
and carefully lowered them to the valley floor
to be taken for conservation.
[ominous music]
Today, they lie in the Rockefeller Museum
in Jerusalem in the exact positions
in which they were found.
These bodies have been carefully buried
and some were laid to rest with grave goods.
One was found clasping the jaw of a wild boar.
It seems likely they were buried this way for a reason
and that they had a belief in the afterlife.
It's the first time in the human story
we see clear evidence for supernatural belief.
These were fully modern humans,
and their bones have been dated to around 100,000 years ago.
But how did they end up here
on the far side of the deadly Sahara?
[wind gusting]
There's another new branch of science that could help.
Climate modelling.
We've commissioned some of the world's
top climate scientists to work out the climate
in every part of the world,
but not for the present, for the past.
For months, simulated models
were processed by super computers
and have revealed details of changes in temperature,
rain fall, sea level and vegetation.
[thunder rumbling]
There have been some fairly dramatic changes in climate
over the last 100,000 years or so, so,
um, and these would have had a big impact
on modern humans in terms of how they live,
where they can live,
where they can migrate to and so in that sense,
it's very important to understand the climate
over the whole of the globe at several points in the past.
[narrator] So what does this tell us
about how we left Africa?
The region of North Africa, the Sahara and the Middle East,
you think of at the moment as being very dry,
um, you think of deserts and sand
and very hot and arid basically,
but 125,000 years ago
it was actually fairly, fairly different to that.
[Joy] And if we run the climate model forward through time
from 140,000 years ago,
you can see in particular the region around the Sahara
gets a lot more green
when you get to about 125,000 years ago.
[Joy] You can see a kind of a northward extension
of this green bit into the Sahara.
It was a lot wetter,
there were rivers and lakes and wetlands
and also the surface
was actually quite well-vegetated.
This would probably have meant
that animals and humans could have,
could have followed this as well.
[chanting in native language]
[narrator] So around 125,000 years ago,
the climate radically changed
and the biggest, driest
most impassable desert in the world briefly blossomed.
For a few thousand years even the massive Sahara Desert
would have looked more like the East African plains.
A welcoming home for animals and our ancestors.
[rumbling]
[rasping]
[narrator] Gradually, humans could have followed
the game further north.
Eventually, some arrived in Israel
where they lived for many thousands of years.
[chanting in native language]
So is that the mystery solved?
Is this how we left Africa?
Well, these are certainly the oldest remains
of our species found anywhere outside of Africa,
but were they our ancestors?
It seems not.
The astonishing finds in the Mount Carmel caves
are the end of this archaeological trail.
No other evidence has been found anywhere
to suggest humans survived here or continued the journey.
The story of this particular pioneering group
does not seem to have a happy ending.
And once again, it may all be down to the climate.
[ominous music]
[Joy] We can run the climate model forward again
from about 125,000 years ago and see what happens.
[Joy] And what happens over North Africa
and the Middle East is that
as you can see all that green respectively got
a lot more drier, a lot more arid,
there's a lot less rain fall occurring,
and so, the vegetation has been replaced by desert.
[Joy] There would have been less water available
and so in effect it would be a,
a lot harder place for people to have lived,
and certain regions would have been
almost completely uninhabitable.
[narrator] This expansion of the desert
may have been disastrous
for the people who lived in the Skhul Caves.
If the animals that they hunted for food disappeared,
then starvation would have become a reality.
And at the same time,
the route across the Sahara back to Africa
would have been shut.
It seems that these people,
the first of our kind known to have left Africa,
simply died out.
So if these people are not our forebears,
what route did our ancestors take out of Africa?
We know the Sahara had turned back to desert,
so we can pretty confidently rule out a northerly exit route,
which leaves just one remaining option, the sea.
So what would be the most likely sea crossing
for a group of early African hunter gatherers?
One option is the Red Sea.
It separates Africa from Arabia and at its narrowest point,
it is only 30 kilometers wide.
[chanting in native language]
The Arabic name for this place is the Bab el Mandeb
which is usually translated as the "Gate of Grief."
But new research suggests
that in an ancient language of Southern Arabia
a better translation would be the "Gateway of the Crossing."
Could this be a clue as to how we left Africa?
[thunder rumbling]
Whilst 30 kilometers may not sound like much,
it's a huge barrier
if you don't have a sea going vessel.
So how might people have made the crossing?
Ironically, it may have been down
to the same change in climate
that trapped the people in Israel.
At the same time as the Sahara
is beginning to dry out in, in north Africa,
it's forming large deserts again,
we're heading into a glaciation,
so that means a formation
of big ice sheets over north America and Europe
which lock up water from the ocean
and this means a drop in sea level occurred,
and we can run the model forward through time to see this.
[Joy] And if we look in the Red Sea region,
we can see that a lot of new land
is being exposed because of this.
And when you get to about 70,000 years ago,
you can see that there's a lot of new land around here,
and that the distance, um, to cross from Africa
over to the Arabian Peninsula by sea is reduced greatly.
[narrator] In fact, this drop-in sea levels meant
that the shortest distance across the Red Sea
fell to just 11 kilometers.
Was this the opportunity people needed
to take the leap from Africa to the rest of the world?
[chanting in native language]
They may have had good reason to make the journey.
As the climate changed, planes dried out
and the sea became more salty.
Their sources of food were under threat.
The pressure to find new lands and opportunities
may have made a starving population risk everything
and make the crossing.
[rumbling]
A journey that could have happened
sometime around 70,000 years ago.
But if the crossing itself wasn't tough enough
what awaited them on the other side
seems even more treacherous.
[calm music]
Today, Arabia is a brutal desert,
not dissimilar to how it would have been at the time
of this potential crossing.
Temperatures in the heart of the Arabian Desert
reach 50 degrees Celsius,
it's one of the hottest places on the planet.
Did our ancestors really manage to survive in this place?
It sounds unlikely.
[tense music]
But Dr. Jeff Rose is not one to be put off by a challenge,
even the challenge of finding evidence
in such a forbidding place.
He's one of just a few archaeologists
to search for clues to our ancient past in this region,
and he believes that this dead place
was once alive with our ancestors.
[engine revving]
To test his claims, we took him on a route
through the Arabian Desert which he'd never seen before
and asked him if he could find any signs of ancient life.
[Jeffrey] It's actually quite a special location.
If you look around you see all these black rocks
that are lying across the surface,
well, they aren't really rocks,
they're all ancient stone tools made by early humans.
[Jeffrey] Well, I've picked up a few just,
just lying on the surface here and these are called cores,
so these are the pebbles
they would have held in this hand,
they would have had a harder stone in this hand
and they would have knocked flakes off of, off of this,
which would have then, then been turned into tools,
and these particular cores are called blade core,
so it's, it's very specific technology
where they're trying to remove these long, thin blanks
which would then be turned into scrapers or arrowheads
or something like that.
And this is, this is a particularly interesting one
because we can see they've,
they've removed flakes here and here
and then they got themselves into trouble, they hit it here,
they didn't hit it quite hard enough
and you get what's called a hinge fracture
running along this edge here,
and it's a mistake.
[Jeffrey] So they probably just said "ah"
and threw it over the side and picked up another piece
and tried again.
It's everywhere in Arabia.
[narrator] And that's why they litter the ground.
This place was a stone tool factory.
This and, and the entire plateau
that goes on for hundreds of kilometers
to both the east and the west would have been a special place,
because this raw material is everywhere.
[Jeffrey] Raw material would have been as important to them
as oil is to us today.
They absolutely needed it to survive, to make their tools,
to hunt, to fish, to skin hides, to make clothing,
to make structures, to get shelter from the sun,
so it was absolutely essential.
[narrator] But who were the people who left these tools?
Could they really be anything to do
with a crossing of the Red Sea around 70,000 years ago?
Everything is lying on the surface
and surface sites can't really be dated
using traditional methods.
However, we can say
based on the technology that we see here,
this very specific blade technology,
and there is a site dated in Yemen
to about 70,000 years ago with the identical technology
and then another site which we have found over,
just over those mountains dated to about 12,000 years ago,
so we can put it somewhere in that range,
between 70,000 and 12,000 years ago.
[narrator]But how could anyone have survived
in this parched landscape?
[calm music]
Jeff believes the answer could lie a few miles
from the stone tool factory.
Within a short distance the desert undergoes
a remarkable transformation.
[tranquil music]
[mooing]
Apart from the camels,
it's hard to believe that this is still Arabia.
This is the fertile Wadi Darbat
in the Dhofar mountains of Oman.
It sits on the edge of a very active weather system
which forms out in the Indian Ocean.
[thunder crashes]
The system's defining feature
is the monsoon which blows in every summer.
[thunder rumbling]
With it comes the rain,
which makes this place so lush and green.
[mooing]
And it could be that this simple accident of climate
is absolutely key to our human journey,
because it may have allowed our ancestors
to establish a crucial foothold
in this otherwise inhospitable new world.
As an oasis in the middle of the desert,
this may have been a refuge for some of our ancestors
through the worst of the driest climate phases.
But on either side of this refuge
the desert still stretched for hundreds of miles.
So how did these pioneers
manage to move on through Arabia?
[engine rumbling]
If they really came this way,
our ancestors must have found a source of water
not only in Wadi Darbat but further east.
The clue to how they did it
may lie not in the Arabian Desert
but under the waves of the Indian Ocean,
because below this boat
is a hidden source of fresh water.
Seventy thousand years ago,
the Arabian coastline looked very different to today.
When our ancestors first saw it,
sea levels were lower
and what is now sea was then land.
Crucially, the coast was dotted with springs of fresh water.
So if our ancestors came this way,
they could have found the lifeline.
A fertile land of fresh water lakes and rivers,
leading to what is today the Persian Gulf.
The Persian Gulf is probably one of the most important places
in the ancient world,
because it's the shallowest inland sea in the world,
it's only about 40 meters deep,
so when that sea level was lower,
the entire area was this exposed flood plain
and all those drainage systems around Arabia
that are coming from the Zagros Mountains,
the Torus Mountains trapped beneath Arabia itself,
flow into the gulf and they come bubbling up in the surface.
So in ancient times you have lakes, estuaries,
fresh water rivers,
and only when the sea level was lower
would it have been available,
so it really shows why that coastline was so important
for the early humans moving out of Africa.
[chanting in native language]
[narrator] The springs of fresh water
along the coast of Arabia
could have provided those early pioneers with water,
the sea offered food
and the desert gave them tools
to survive the great journey to the Persian Gulf.
[chanting in native language]
And there's one final clue
to how significant this place could be.
When an early civilization grew up in this region,
its people gave a name
to the type of landscape they lived in.
[Jeffrey] It was everything, it was paradise.
In fact, the name for it by the people living
along the northern shoreline was Eden.
[narrator] It may be a coincidence,
but this is the same word used in the bible
for an earthly paradise.
But it may well have been that from this Eden,
humans gradually spread out
in all directions eventually to Europe,
Australia, Asia, and the Americas.
When and how did they make these journeys?
And how did the experience transform our ancestors
and make us into the people we are today?
These are the questions we'll seek to answer
in the Human Journey.
[closing theme music]