Ever since humanity
went into space,
We've looked down on the marvels
of our civilization.
We've achieved
incredible things,
But we didn't do this alone.
Thanks to space technology,
we are gaining new insight
Into how the dynamic life
of our planet
Has influenced
the rise of our species.
We're finding evidence
that our exceptional brains
May be an evolutionary response
to an unpredictable climate.
When you really look
at what our brains do,
They're our organ
of adaptability.
We're revealing
how a lifestyle revolution
Triggered
the growth of civilization.
These are probably
the earliest ancient roadways
In the world.
And we're uncovering
the full power and peril
Of unleashing the energy
stored within our planet
Hundreds of millions
of years ago.
That's an energy revolution,
And there are climatic and
ecosystem consequences to that
That are going to be present
for thousands of years to come.
Humanity's
very success is pushing us
And our environment to the edge.
We have become a force
to match anything that you see
In a billion years
of earth history.
But our technology
gives us a chance
To shape what happens next.
We can actually
conceive of a desirable future
And build a global plan
to get to that future.
That's the challenge for
humanity in the 21st century.
This is the story of us,
Of the life of earth
in the age of humans.
From its birth
4.5 billion years ago,
Planet earth has endured
constant change...
Devastating impacts
from asteroids and comets,
And tectonic shifts generated
By the churning heat
beneath its crust,
Transforming
the planet's environment.
All life that clings
to its surface
Evolves to survive
Or succumbs to extinction.
Our story begins
300,000 years ago.
Earth's climate
is colder than today,
With ice sheets
extending from both poles.
In the warmer equatorial zone
on the african continent,
A new creature arises,
A species of ape
with great potential.
They are us...
Homo sapiens.
But 300,000 years ago,
We were not
the only two-legged ape
Wandering the african plains.
2015, southern africa.
In a region rich
in ancient human fossils,
A fantastic new discovery awaits
deep underground.
It's the first time
Paleoanthropologist
dr. Lee berger
Has explored
the rising star cave system.
Lee berger:
I had this map I'd created
Of almost 800 cave sites
That were all entryways
into the underworld
That I hadn't been in yet,
and that was the mission.
Berger has heard
rumors of human remains
Glimpsed
down one of these passageways.
It's challenging terrain
for the scientific team.
Berger:
To travel just 100 meters
Takes 20, 30, 40 minutes,
Depending on how fit you are
and how good you are
At squeezing
through very tight spaces.
It's a torturous journey.
The effort is worth it.
They make an incredible find.
Berger: I was speechless.
I mean, there I saw something
I thought I would never see
in my entire career.
There was
a clearly primitive hominid
Just lying there on the surface
in the dirt.
The body is just the beginning.
Berger and his team
uncover bones
From 15 separate skeletons,
Dating from the time humans
first spread across africa.
Berger: We've had everything
from individuals just born,
All the way
to the extreme elderly,
And everybody in between.
But the bones are not human.
They belong
to a totally new species...
Homo naledi.
Berger: Imagine
if you're standing out here
300,000 years ago.
A group of homo naledis
from 500 meters...
They'd look very little
different from humans
Because they're walking
on two legs.
As they approach,
You're going to start seeing
things that are different.
You're going to notice that
the proportions aren't right,
That the heads are small,
that the shoulders are narrow.
When they got about 50 meters
from you,
You'd realize that's
not a human coming at you.
There'd be no mistaking.
Naledi now joined the ranks
Of at least three other
human-like species
That existed in parallel
to homo sapiens
300,000 years ago,
Exhibited here in the national
museum of natural history.
Rick potts: We used to see
human evolutionary history
As that March of progress
from ape-like to human beings.
Instead, what we've learned is
that there were contemporaries.
Our evolutionary tree
is branching and diverse,
Like the evolutionary trees
Of almost all other organisms
on earth.
But if all these
human-like competitors
Once shared our planet,
Why are we the only ones left?
Potts: None of them
now exist on earth.
We are the last bipeds standing.
Humanity's survival
advantage may have its roots
In dramatic changes
in the earth's unstable climate.
Satellite images
of the western sahara
Reveal remains of a major
river system 250 miles long...
Evidence that this was once
a lush valley.
It's now believed
that every 20,000 years
Throughout humanity's evolution,
Periodic ice ages
swing the african environment
From wet to dry and back again.
Potts:
The past six million years
Have been
the most dramatic period
Of climate oscillation
and change in landscapes
Ever since the extinction
of the dinosaurs
65 million years ago.
Any species that can't cope
With rapid environmental change
will not endure.
Potts: The boundary
between survival and extinction
Was really adaptability,
The ability to adjust
to changes in the landscape.
Scientists think the need
To solve
environmental challenges
Spurred homo sapiens to evolve
a uniquely adaptive brain.
We developed imagination
and language skills
Our rivals lacked.
Potts: When you really look
at what our brains do,
They're our organ
of adaptability.
With language,
we have the ability
Of not just having our brains
being inside our skulls,
We have the possibility of our
brains being shared with others
In ways that go far beyond
What any other organism
was capable of doing
Up to that time,
including earlier humans,
And that capacity
to socially network our brains
Meant that innovations could
start to not only be invented
But also to accumulate.
That was our real card
That we could put down
on the survival table.
Over 200,000 years
of intense competition
In a fluctuating climate,
We become the only homo species
still surviving in africa.
Homo naledi
and our other african rivals
Are overwhelmed.
And it's time for our mental
advantage to go global.
An extreme ice age
causes sea levels
To drop nearly 250 feet.
Sections of the red sea
narrow to just a few miles wide.
It's a new route out of africa
That some of our ancestors
now use
To spread across the world.
The decline and disappearance
Of all remaining
rival homo species
Can be traced
to this great migration.
And our rivals
are not the only casualties.
We now begin to have
an impact on the planet
Unlike any other animal
before or since.
The latest ice age
approaches its peak.
Over the last 30,000 years,
Our ancestors have spread
across the globe.
But their path to the americas
was hindered.
Deep oceans proved
a formidable obstruction,
But now this barrier disappears.
Expanding ice caps
cause sea levels
To dip to record lows.
In 2014, a satellite survey
between siberia and alaska
Measures the shallow contours
of the seabed.
Here is conclusive proof
that 25,000 years ago,
A 600-mile land corridor
opens up.
Across it, animals and humans
start to migrate.
But evidence from this late
migration tells a bigger story...
That humans have by now amassed
The power to unbalance
an entire ecosystem.
In michigan, a team
of paleontologists investigates
The remains of an ice age lake.
Team leader dr. Dan fisher
unearths incredible evidence
Of the deadly impact
of this human migration.
Dan fisher: What's that?
There's something there.
Okay, this shape right here
Is the central column-like
section of a vertebra,
The part that supports weight.
Oh! There's another one
below this.
These are the remains
of an icon of the ice age...
The woolly mammoth.
Fisher:
Humans living here at this time
Would absolutely
have encountered them
On a more or less daily basis.
Before humans arrived,
Mammoths and other large animals
roamed throughout the americas.
But they had never faced
a predator this cunning.
Fisher's evidence shows
Just how sophisticated
these hunters were.
Fisher: I think this comes
from the base of the skull
That was cleaved off.
This would suggest,
not in a single piece,
Maybe in multiple pieces,
We have this very targeted
damage on the skull.
They broke in
just where it was necessary
To most easily remove
the entire brain.
The early humans
aren't just eating
The nutritious brain.
They know how to prepare
and preserve it.
Fisher: The fact
that it's found in the pond
Is consistent with the notion
That they store brains in skulls
in lakes for a month or two
To sort of season them
And, and get them sort of
to just the right consistency,
But then
they'll eat them directly.
Mammoths once
dominated this landscape.
But fossil evidence shows
that by 10,000 years ago,
Their numbers
are in steep decline.
And the clues
point to one culprit.
Fisher: You might think
that a small human population
Would never make a dent
in the populations like this,
But these are
slow-reproducing animals.
When they suffer losses
to hunting year after year,
It has the potential
to have a serious impact
On the population as a whole.
The evidence strongly supports
human activity
As the principal cause
of the mammoths' extinction.
The end of the mammoths is proof
That as early
as 10,000 years ago,
Our adaptive brain
gives us enormous influence
Over our environment.
But globally,
our scattered populations
Still total
fewer than five million.
In this ice age world,
our numbers are limited
By the scarcity of the wild
resources we depend on.
But the planet itself
will soon create opportunity
For a new way of life.
Humans will harness
the power of cultivation,
Transforming
not just our population,
But our societies,
even the whole ecosystem.
Our planet today
is lit up by civilization.
But 10,000 years ago,
Not a single town or city
exists.
All humans are nomads.
They live in small groups
of hunter-gatherers,
Always on the move,
Hunting wild animals
and foraging wild plants.
This lifestyle has changed
little for over 100,000 years.
But just 5,000 years later,
grand structures appear
Alongside teeming cities,
Hallmarks of civilization.
It's a dramatic turning point.
And a set
of top secret photographs
May just have revealed
where it all began.
In the 1960s,
at the height of the cold war,
America launches
a spy satellite program...
Code name: Corona.
For decades, the 800,000
satellite photographs
Of the corona program
remain top secret,
But in 1995, an archaeologist
from the smithsonian institution
Persuades the government
to declassify the images.
This treasure trove of data
May just have identified
the world's first city.
Anthropologist dr. Jesse casana
has spent years
Studying corona spy photographs
of the middle east.
The images are invaluable
Because 50 years ago
when the photos were taken,
The countryside
was far less industrialized.
Ancient details remain visible,
if you know what to look for.
Jesse casana:
We were able to document
Something like 10,000 previously
unknown archaeological sites
That, through the history
of 150 years
Of archaeologists
working in the middle east,
No one had ever documented.
In 2007,
The spy images
herald a breakthrough,
Revealing details
that are causing experts
To reclassify one settlement
as the world's first city.
4,000 years older
than the pyramids of egypt,
It's called tell brak.
Casana: It looks like
a gigantic hill today,
And surrounding the big hill
is a fan of other settlement
That encompasses
a very large area.
It's the remains
of an ancient city
That was probably first founded
more than 6,000 years ago,
And that makes it perhaps
the oldest city in the world.
Settlements like
tell brak only start to appear
After a dramatic event
transforms the environment.
It's the end
of the last ice age.
Earth's climate
radically shifts.
The planet is at its warmest
point in 100,000 years.
Where tell brak lies
is an area of the middle east
Known as the fertile crescent.
It's now
that it becomes fertile.
Rainfall and temperatures
increase,
Leading to a great expansion
of grassland.
Climate change is about to fuel
a food revolution.
For millennia,
humans foraged wild grass seeds,
But now abundant wheat
and barley
Prove easy to grow
and to control.
Some people begin to settle,
To nurture
and protect their crops.
They gradually give up
the hunter-gatherer lifestyle
To become farmers.
From this point forward,
Human reliance on cultivated
plants and domesticated animals
Will begin to change
the landscape.
Potts: With agriculture,
people began to have an impact,
Taking a few plants,
then breeding them,
Growing them, and rejecting all
of the other plants around them,
Simplifying those ecosystems.
Tell brak is special
because the earliest evidence
Of this shift to agriculture
Is visible
in the corona images...
The world's first roads.
Casana: What we can see
Are these,
these dark linear features
That extend out from the site
like the spokes on a wheel.
They're really long.
They extend four or five
kilometers, and what they are
Are the remains of probably
the earliest known roadways
In the world.
What we are able to reconstruct
Is that, in the immediate
hinterland surrounding the city,
There would have been
extensive fields
Of intensively cultivated
wheat and barley.
The sheep and goat
that lived with the people
Here in tell brak,
They would need
to pass by those fields,
And they didn't want
to trample the wheat,
So they would be
kind of constrained,
And so that's how we get
these roadways forming.
They served as passage
For large herds of sheep
and goat and other animals
To come in and out of the city.
The settled populations expand,
Overwhelming
the remaining hunter-gatherers,
Transforming the landscape
With fields, villages, towns,
And eventually cities.
As these cities become the hubs
of great civilizations,
This is the moment humanity
becomes visible from space.
Over the next
few thousand years,
Agricultural revolutions
occur across the globe.
Each civilization is built
Around locally cultivated
plants.
In china and southeast asia,
rice and millet.
In the americas,
corn or potatoes.
And wherever
agriculture takes hold,
There is a population explosion.
By the first century a.D.,
The world population
is over 170 million.
By 1500, it's 500 million.
The footprint
of expanding human populations
Spreads over the entire surface
of the earth.
But now,
as long as we rely solely
On plants and animals
for energy,
Our growth is constrained.
Further progress is unlikely
If not for a hidden source
of power lying under our feet.
Above our heads today,
Scores of satellites
orbit the earth.
Their mission... treasure seeking.
Using an array of sensors,
they probe the planet's surface,
Seeking an energy bonanza
Buried hundreds of millions
of years ago.
Over the earth's
4.5-billion-year history,
It has experienced
many violent transformations.
But through them all,
The sun has shone,
bathing the surface with light,
A source of incredible energy.
When life takes off in earnest,
It does so because it has
perfected photosynthesis...
Using light energy
to trap carbon from the air
In leaves, stems, and trunks.
For over 100 million years,
immense forests swamp the globe,
And the seas fill with life.
As plants and animals die,
their remains become fossilized.
They lock up the solar energy
that created them
In coal, oil, and gas,
Which millions of years later
Will utterly transform
human societies.
Since the start of civilization,
To keep the fires burning,
Populations rely on wood
for fuel.
And by around 300 years ago,
Populated areas
like europe and china
Burn up most of their forests.
If they use up all their wood,
Their civilizations
may soon collapse.
But in the 18th century,
Humans tap the true potential
of fossil fuels...
Developing machines to harness
This buried source
of rich energy.
Over just a few hundred years,
They fuel humanity's
great leap forward...
The industrial revolution.
Scott wing: We're tapping into
this fossilized source of carbon
That's been deposited over
hundreds of millions of years,
And we're then
burning that energy up,
And that's really an energy
revolution that's so recent
That I, I think sometimes
We don't realize
how important it is.
Access to fossilized energy
Puts human civilization
into overdrive.
Wing: The energy revolution
lets all of us
Consume a huge amount of power.
The amount of energy that each
one of us use in our daily lives
Is equivalent to having,
You know, more than 100 people
working for you full-time.
Gasoline-fueled
vehicles link cities.
Coal- and oil-powered ships
link continents.
Technological innovation
allows instant communication
Across the planet.
Civilization
is now truly global.
But this energy revolution
Also unleashes
humanity's potential
For incredible
destructive power.
The explosion
of the first atomic bomb
Marks a turning point
for humankind.
Over the following decades,
More than 2,000 atomic warheads
are tested.
They generate an unprecedented
release of radioactive dust
That spreads across the globe.
Wing: If you were a geologist
ten million years from now,
Some of it
would still be visible
In the sediments deposited
in the mid-20th century.
This is the moment
Geologists consider the official
start of the age of humans,
The point when a species of ape
achieved the power
To determine the destiny
of all life on earth.
So far, the fear
of mutual destruction
Has kept us
from nuclear holocaust.
But in the age of humans,
There are other ways we can
threaten our own survival.
It took humanity 300,000 years
To reach a population
of one billion.
But in just two centuries,
Our fossil-fueled civilization
has rocketed to seven billion.
We are now spread,
in increasing density,
Over the entire habitable
surface of the globe.
Kirk johnson:
During my life span,
The population of the planet
has more than doubled.
The impact of that, of course,
Is that people need
food, land, iphones,
Cars, buses, cities.
So as humans grow, they're
appropriating the natural world
At a staggering rate.
It's estimated
that to feed everyone,
Farmers will need to produce
As much food
in the next 40 years
As they have
in the previous 8,000.
But as we turn most of the globe
to agriculture,
We are destroying
animal diversity.
Today, livestock farming
Covers a quarter
of all available land.
In just 50 years,
wild mammal numbers
Have dropped
by almost 60 percent.
Johnson: One of the things
we've been seeing is over time
Is that there are less animals
than there used to be.
There are less fish than
there used to be.
There's less wild land
than there used to be.
Extinction rates
are 1,000 times higher
Than ever measured before.
Wing: How long
are we going to continue
To decrease the habitat
for other species?
Because if it continues,
I think there's not much doubt
That we will end up
in a mass extinction.
We may not notice
The extinction
of most wild animals,
But our addiction
to fossilized energy
Is becoming impossible
to ignore.
Burning fossil fuels
pumps huge quantities
Of ancient carbon
into the atmosphere...
Far too much for today's
plants, soils, or oceans
To reabsorb.
Wing: We're using
the fossil fuel reservoir
A million times faster
than it was generated,
And there are climatic and
ecosystem consequences to that
That are going to be present
for thousands of years to come.
Measurements from space probes
Confirm that our atmosphere
is altering at an alarming rate.
Gavin schmidt: We've increased
the amount of carbon dioxide
By more than 40 percent.
We've more than doubled
the amount of methane,
Another trace gas
in the atmosphere.
Each one of those things
is changing the climate,
Is changing the weather.
Earth's history tells us
Rapid change in climate
can be disastrous.
Wing: We have past examples
Where the amount of co2
has gone up
And the earth's climate
has warmed,
So it's a fact.
56 million years ago,
The climate warmed
nearly 14 degrees fahrenheit
Over a few thousand years.
Fossils show that to survive
the conditions,
Most species of mammal shrank
in size by over a third.
But under our watch,
The climate is changing
at a much faster pace.
In the last two centuries,
Ocean acidity
increased by 25 percent.
In the last 100 years,
sea levels rose 8 inches,
And in just 50 years,
Nearly half of our arctic ice
has disappeared.
We are creating
a new planetary environment.
Schmidt: We're pushing a system
In a direction
that it's never been before.
Just in the space of 150 years,
We have become
a geological force
To, to match
almost anything that you see
In, in a billion years
of earth history.
We face a calamity
of our own making,
But our species came this far
Through brain power
and the tools we created,
So can our tools
come to our rescue?
The problems caused
by humanity's great expansion
Have been brewing for centuries.
But scientists believe
It's the actions
of this current generation
That will decide the future
of the planet.
Potts:
Humans are a turning point
In the history of life on earth.
We've become a global phenomenon
And responsible
for the intensity
Of what is going on
to our planet,
To the ecosystems on which
Not only other organisms,
but human life depends.
This is, in many ways,
Our own survival challenge
for the future.
And now we have
technology to help us,
Satellites to monitor our planet
and help find solutions.
Our orbiting probes have already
helped avert a global disaster.
In the 1980s, above antarctica,
Nasa satellites
provide crucial confirmation
Of a gaping hole
in the ozone layer.
This thin layer of gas
high in the atmosphere
Is a vital protective shield
against the harshest solar rays.
Schmidt: We tan,
we enjoy being in the sun,
But if we were in the sun
without an ozone layer,
We would burn almost instantly,
And it would be very, very
difficult for life to exist.
The culprit is a side-product
Of globalized industry,
Ozone-destroying man-made gases
Used in aerosols
and refrigeration.
Spurred
by the satellite evidence,
Politicians around the world
unite in action.
Margaret thatcher:
No one can opt out.
The chemicals are banned.
Decades later,
Ozone levels are
on the road to recovery.
Schmidt: We avoided the cliff.
Nobody predicted this.
What would have happened?
It would have reconfigured
life on earth.
Space technology
helped prevent disaster.
Given the chance,
The atmosphere has the power
to heal itself.
Other satellite studies
show that some animal species
Also appear to show resilience
in the age of humans.
In downtown chicago,
Dr. Stan gehrt
uses gps technology
To study
a population of coyotes.
Stan gehrt:
It's extremely difficult for us
To even pick up their signals
on the ground,
But the satellites
can pick them up.
Radio-collaring
over 400 coyotes,
Gehrt documents how this species
is thriving in the human world.
Gehrt: One of the most amazing
things is just how many coyotes
Can live
in a major metropolitan area
And live so close to people.
We estimate that there's 3,000
to 4,000 coyotes here.
We have coyotes
that are literally
Within just a few yards
from people on a regular basis
With people not knowing
that they're there.
They survive by adapting
To the urban environment.
Gehrt: Coyotes have to
learn traffic patterns.
They have to learn
how to cross roads
And avoid getting hit by cars,
And that is the biggest risk
to their life down here,
And yet they're able to do that.
The patterns
that we're seeing in chicago
With coyotes
moving into the city
Is being seen in virtually
every single metropolitan area
Across north america.
If we can make space for nature,
It can survive alongside us.
Satellites can also provide
A path to preserving
animal diversity.
Radio-tagging technology
Allows the mapping
of wildlife migration routes
Thousands of miles long,
Maps we can use
to create protected corridors
To save species
from human interference.
It's just one example
Of how space data
helps protect our planet.
Johnson: Truly we live
in a remarkable time,
When we as humans
have technology,
We have the ability
to plan ahead,
We know our geologic past.
We can put all that together
And actually conceive
of a desirable future
And build a global plan
to get to that future.
That's the challenge for
humanity in the 21st century.
From our perspective,
Our human story
is epic in scope.
Our civilization is measured
in thousands of years...
Our species
in hundreds of thousands.
But the earth measures time
In millions
and billions of years.
Our planet has lived
only half of its life span.
For the last 4.5 billion years,
It has experienced
monumental change.
Species that dominate
then disappear,
Giving rise to new life.
Humanity's entire existence
is a brief moment of brilliance
On this immense timeline.
And the stable environment
we have relied on
Will not last.
Over earth's
next few billion years,
More ice ages,
epic volcanic eruptions,
Meteor impacts, and extinctions
Will be inevitable.
But the planet's history
Tells us some forms of life
will survive.
Where we fit into this future
is up to us.