[MUSIC PLAYING]
LEWIS DARTNELL: Good afternoon.
And thank you all very
much for coming along.
You may have seen me--
not in this room but,
another Google Talks room--
maybe about four
years ago when I
was plugging on books or my last
book, "The Knowledge," which
is all about how you
could reboot civilization
after an apocalypse.
So imagine that the sort
of "Walking Dead" scenario
has actually happened
as a thought experiment.
I don't think the
end of the world
is actually about to arrive.
I don't have "The end
of the world is nigh"
placard around my chest.
But as a scientist, I thought
the notion of the apocalypse,
that the idea of the loss
of everything that we take
for granted was a really
good way of exploring
how all of that works,
how the modern world works
and what's going on
behind the scenes
to provide everything
in our everyday lives,
and therefore what process you'd
have to go through to restart,
to reboot all of that
in terms of transport,
or communications
technology, or growing food,
if you were one of these
hypothetical post-apocalyptic
survivors.
It's essentially the
scientific discoveries
and the technological
inventions that
took us through 10,000
years of human history,
from living in caves to the
modern world of antibiotics,
electricity, and skyscrapers.
And what I wanted to do
for this new book was
pull out the focus even
further and not look
at how human ingenuity, and
discovery, and invention
enables to build
the modern world
and progress through history,
but how the world itself,
the planet that we live on,
has played a crucial role,
a key part in that
story of humanity,
and right back to
the furry beginnings,
our origins as a bipedal
intelligent species of ape
in East Africa through to the
very emergence of agriculture,
and civilizations, and
then through the thousands
of years of history--
the rise and fall of
empires, different cultures,
and societies.
We're up to the modern
age, the modern world
of current affairs you read
about in the newspapers
or modern political maps.
There is the fingerprint,
the signature of features
of our planet
behind all of that,
pulling the strings
in subtle ways.
So I'm not saying that
culture, and sociology,
and people have
not been important
in history, of course they have.
What I'm saying is that--
and if you'll excuse
the pun-- beneath all
of that is the bedrock, is the
foundation of planet Earth,
of processes like
plate tectonics,
or the geographical distribution
of different resources,
the circulation
of the atmosphere
high above our
heads, which gave us
the trade winds and the way
of exploring around the world,
and building these
huge transoceanic trade
routes in the very
beginnings of globalization.
And so this is what
I've tried to explore
in this new book, "Origins,
How the Earth Made Us,"
how Earth and planetary features
have been often neglected
when we talk about history
and these grand themes,
these grand trends over the
centuries and the millennia.
And what I wanted to do
for this afternoon was just
pick out some of what I think
are the most interesting
narratives, the most interesting
stories from this book,
those deep fundamental links
from planet Earth to world
history, to human history.
And we might as
well start the story
at the beginning in the
making of us, in our origins
and evolution in East Africa.
This is our family tree, you
can see on the left hand.
This is the hominin lineage,
the human-like species.
We split.
We diverge from the chimpanzees
about seven million years ago.
And there have been dozens and
dozens of human-like hominin
species, up until Homo sapiens,
which is our own species down
at the bottom in this great big
branching tree of evolution.
And over time, we've become
increasingly more bipedal.
We've walked upright.
We've got better at running
quickly and efficiently.
We've had jumps.
We've had increases in our
cranial capacity, in our brain
size, which has been linked to
increases in our intelligence,
and our cultural
ability, and our ability
to learn and solve problems.
And so commensurate with
all of this body evolution,
we've got increasingly adept
at technology, at tool use.
And the very first tools
two, three million years ago
were literally just rocks strewn
across the East African floor
with some Homo erectus
plodding across the savanna,
stubbing his or her
toe on this rock
and going, ugh,
but then realizing
that what stubby toe
might be very good also
for bashing other stuff with.
And we invented technology.
We invented tools by stuff
we could just pick up
and find lying around us.
And the story from there
was with us getting better
at refining, and
processing, and tuning
what we could extract and
harvest from the natural world
to be better at what we needed
to do, better tools, leading up
to Stone Age
technology of things
like very fine chips
of obsidian or flint,
which give you very sharp
spearheads or arrowheads.
And all of this story of
our evolution as hominins
and all of this
technological development
happened in this part of
the world, in East Africa.
This is the cradle of humanity.
And incidentally,
it's where I spent
my own childhood
growing up in Nairobi
and going most weekends on
safari and going to school
called the Banda, which
is Swahili for mud hut.
I went to the mud hut school
in East Africa, in Kenya.
And one of the key
transformations
that drove our evolution
from tree swinging apes
to bipedal, upright,
running, intelligent hominins
was that the area around us had
to dry out beneath our feet.
You have to turn rainforest,
forest, into grasslands,
into savanna, to drive that
fundamental evolutionary
change.
And there's a very
quirky truth right
in the core of that fundamental
part of our own evolution.
If we zoom out from East
Africa to look at the globe--
so I became a massive
math nerd when
I was researching and
writing "Origins."
I've come from a
biological background.
And all of the maps you'll see
in this talk and the ones which
are figures in the book are
maps I've written myself
by writing some cartographic
software to show
different features
of the planet,
and then layer human things
or other geographical things
on top of them.
So you'll be seeing lots of
full color, high resolution
maps, which I totally
nerded out about.
And if you zoom out
to the entire world,
here's East Africa.
And if you just allow
your eyes to follow around
that equatorial
region of the planet,
it's all smothered
with rainforest--
the Amazon rainforest,
the rainforests
of the Congo and Central Africa,
the rainforest archipelago
of the East Indies.
Apart from this weird
little corner of aridity,
East Africa is dry.
It should be wet.
Everything else in
that part of the planet
is damp, and moist, and
covered in rainforest
apart from where we evolved.
And so what was going on?
What drove that drying
out of East Africa
from beneath our
ancestors' feet was there
was a great big plume
of magma rising up
from deep in Earth's
interior and pushing up
into the underside of the
continental plate of Africa.
And if you strip away
the satellite image
and show you instead the
topography of the land,
the landscape of East
Africa, colored in red hair
are the Ethiopian highlands.
This is literally
the zit that formed
on the face of planet Earth
as this magma plume rose up
and pushed beneath it and
then started to rip, tear open
the crust of the planet.
It's this characteristic
Y shape of the Red Sea
that ripped so deep
that it then filled
with the ocean, the
Gulf of Aden over here.
And then the third arm
of that Y shape feature
is the East African Rift Valley,
passing all the way down south
here.
And the landscape
of that Rift Valley,
of that feature
of plate tectonics
of Africa tearing itself apart,
is you have a very low valley
floor.
You have a tube.
You have a tunnel of
a low valley floor
with towering mountainous
ridges on either side.
There are walls that are
formed in East Africa that
block moisture coming
in from the ocean
or coming in from the
rainforests on the other side.
And it's that rising of the land
of the continent for that magma
plume and the features of
that tectonic Rift Valley
that dried out East Africa
from beneath our feet, that
drove that fundamental
evolutionary process.
But what's been puzzling
paleontologists for quite a
while-- we've only
really started
to understand this now-- is,
well, what was it specifically
about the East African
[INAUDIBLE] that
drove our evolution
to be so exquisitely
intelligent, and
adaptable, and versatile?
Plenty of places around
the world dry out.
There's nothing
unique about that.
What crafted us to
be so intelligent
as a species of ape?
And what's been emerging in
recent years from scientists
is that there is a unique
combination of conditions
in this part of the world.
We have those walls
of the Rift Valley
that collect the rainwater
that does fall, funnel it
down into the lakes strung
along the valley floor.
And so these lakes
are exceedingly--
the level of those
lakes is exceedingly
sensitive to tiny fluctuations
in their local climate,
in how rainy it is
between the hot valley
floor and the rainy,
mountainous ridges.
So the specific landscape
of the Rift Valley
is interacting
with cosmic cycles,
the so-called Milankovitch
cycles in Earth's tilt
or wobbles in its
orbit around the sun.
And during periods of this
extreme climactic instability,
we see bursts of evolution
in that hominin line--
emergence of new species,
jumps in brain capacity,
jumps in the tools
that have been created.
We are, very literally,
children of plate tectonics.
It's that Earth-moving
process that
drove our evolution as such,
as intelligent species of ape.
But although plate tectonics
here created us as a species,
we didn't remain in our cradle.
We've come as far away
as places like London.
We have migrated
around the planet.
And this brings us to a
different chapter in Earth's
history and in our own history.
What was it that
enabled humanity
to migrate out of East Africa to
colonize every major continent
around the planet, to become
the most widely spread animal
species in the world?
This is the world, the
map we'd recognize today.
We're familiar with those
outlines of the continents,
with the coastlines.
But the world did
not look like this
when we were emerging and
migrating out of East Africa
about 70,000 years ago.
The world looked very,
very different back then.
The world was in the depths
of the last great ice age.
And in fact, that last ice
age was only the most recent
in a sequence of 50 or 60
ice ages in the last two
million years, this pulse, after
pulse, after pulse of ice age.
And the most recent
one saw the growth
of these great big glaciers
and ice sheets, particularly
across the northern hemisphere.
And this sucked out so
much water from the oceans
that sea levels around the world
dropped by over 100 meters--
up to about 120 meters--
and literally
exposed the seabed.
The seabed emerged as dry land.
And of particular importance
for the human story,
for our migration
around the world,
particular land bridges
appeared between islands,
between different landmasses.
So the Sunda land bridge and
the [? Soheur ?] land bridge
opened up in Southeast
Asia and Australasia.
We could migrate along the
southern margin of Eurasia,
around India, down
through Southeast Asia,
and simply walk to colonize
those islands without having
to get our feet wet.
And most critically,
of most importance
to the thousands of
years of human history
after this, we were able to walk
across the Bering land bridge,
from Northeast Siberia
all the way across
into Alaska and the Americas.
And as we were migrating out of
our birthplace in East Africa,
we encountered our
sibling species--
other hominin species,
other human-like species
that had migrated out
of Africa before us
and were living in
Europe and Central
Asia-- the Neanderthals, who
you've probably already heard
of.
But there were also
the Denisovans,
a whole species of humanity,
sharing the world with us.
Very recent, only a few tens
of thousands of years ago.
And all we know about this
entire species of humanity
has come from a few tiny
fragments of finger bone.
That is all that has
remained of that species,
preserved and
protected in a cave.
And we've been able to extract
the DNA out of those finger
bones, sequence
them, and recognize
the signature of the
Denisovans in our own DNA,
in our own genome.
We not just encountered
these other human species,
but we got quite
friendly with them.
We interbred with them.
We carry their DNA
inside ourselves,
like a cargo, a genetic
cargo, as we then
continue that migration to
populate the entire planet.
And when we crossed into
North America and then
into South America, no
previous hominin species
had ever made it that far.
As you walk down
through the Americas,
we were walking where no human
species had ever trod before.
And then, with the easing
of the last ice age,
the melting of the great ice
sheets, the rising of the sea
level, these two great
hemispheres of the planet,
of Eurasia and the Americas,
once again became severed,
became separated by each
other as the sea levels
rose and inundated, resubmerged
that Bering land bridge.
These two human
populations, which
were essentially
genetically identical,
both had access to wild
species of plants and animals
that they could domesticate
and invent agriculture,
and start on two
independent experiments
in civilization, completely
out of contact with each other.
And it was only
thousands of years
later when Europeans
started applying technology
of sails and ships to cross the
Atlantic, first with Columbus,
to rediscover these lands that
these two great civilizations,
or clusters of civilizations,
once again came
into contact with each other.
Now, the first civilizations to
arise after we had migrated out
of Africa, exploiting those
quirky climactic conditions
of the last ice age and
the very low sea levels--
the first
civilizations who arose
were in this part of the world.
This is the Arabian Peninsula.
I've just shown for
you here the plate
boundaries-- those orange
lines, the fractures
in the skin of our planet
where these great, big chunks
of crust, the tectonic plates,
are moving and drifting
around relative to each
other in a very, very
slow timescale from a
human point of view,
but scudding across the
surface of the earth
when you look at the whole
history of the planet.
And we've talked already about
the opening up of the Rift
Valley, and the Red Sea,
and the Gulf of Aden
that drove our own evolution.
And it was almost as
if a chunk of Africa
was torn off as
Arabian Peninsula,
and has been drifting
away ever since.
This whole Arabian Peninsula
has been swinging away
like a barn door
caught in the wind.
And it slammed into the
underside of Eurasia--
the Eurasian
continental landmass.
And when continents
slam into each other,
you drive up mountain ranges.
And what happened here
was the crumpling up
of the Zagros mountain range.
And running alongside parallel
of the Zagros mountain range
is the region that we've
come to call Mesopotamia,
the very rivers of the
Tigris and Euphrates
flowing down alongside the
feet of the Zagros mountains.
And this Mesopotamia, this
land between the rivers,
around 3,000 BC, became
the land of cities.
We saw an emergence of the first
civilization, the Sumerians.
People had settled down,
domesticated wild plants
and animal species, put
them into the fields
to grow as agriculture, built
up enough of a food surplus
to feed growing numbers of
people, which clumped together
into increasing densities
in towns, and then cities.
And civilization emerged
out of that process.
But even here, we see the
fingerprint of the tectonic.
It was a tectonic process
that drove our evolution
as a species.
It was a tectonic setting that
created the perfect conditions
for the emergence of the very
first civilizations, as well.
Because whenever you have a
great big range of mountains,
like the Zagros here,
it sags right down
into the crust of the planet.
You get a line of mountains
and the characteristic tectonic
trough running alongside
it where it's sagging down.
And clearly, the rivers
Tigris and Euphrates have been
flowing downhill through that.
But they've also been eroding
out the very young mountains
up here, which are
still rich in nutrients,
and depositing that as
very, very fine, silty,
alluvial soil-- very, very
fertile soil, which are well
watered by those rivers.
The reason agriculture
became so productive
and civilization emerged here
is because the Earth had created
the conditions that made it
very, very simple, because
of this foreland basin sagging
down alongside that mountain
range.
And when the Mesopotamian
civilizations
were emerging around 3,000 BC
on the other side of the planet,
around in India, in an
identical tectonic setting,
in the foreland basin, the
tectonic trough running
alongside the Himalayan
mountain range,
the Indus Valley
civilization was popping up
around the same time.
Two different
parts of the world,
same moment, same
tectonic setting.
It's this Earth process
that also gave us,
betrothed us
civilization itself.
Now, civilization spread
from these origin points,
from these sources, from
places like Mesopotamia,
and spread into
the Mediterranean.
And the Mediterranean's
a place that we've
heard lots about from history
lessons and TV documentaries.
It has been a bubbling,
broiling cauldron
of dozens of different
cultures, and societies,
and civilizations, and
empires for thousands
of years of history, right from
the beginnings of the Bronze
Age through the Phoenicians
and Minoans, the Etruscans,
the Ancient Greeks, the Romans.
But when you think about it,
all of this ancient history,
all of these classical
civilizations, all
of antiquity, all
of that activity
was happening on one half
of this oval-shaped sea
of Mediterranean, and
not the other half.
All of that civilization
and activity
was happening on the northern
part, the northern lip
of the Mediterranean, and not
the North African coastline,
not the southern part.
These places aren't far apart.
There's only a couple hundred
kilometers from one side
to the next.
So why has there been
this great disparity,
this great difference that's
continued for thousands
of years through
history between one
side of that sea and the other?
And to understand that, we need
to see where the Mediterranean
Sea came from.
And it turns out,
the Mediterranean
is no more than a tiny
puddle left behind
as the remnant of a
once vast, vast ocean--
an ocean that was as
big as the Atlantic
in its heyday, which
is called the Tethys.
And if you wind
back Earth history
almost a quarter
of a billion years,
240 million years ago,
all of the continents
had slid into a single great
landmass, a supercontinent
called Pangaea, the all land.
And held in the cup of the
C-shaped supercontinent
was the Tethys Ocean.
And almost as soon as
Pangaea had formed,
it started tearing
itself apart again.
An unrelenting process of plate
tectonics and continental drift
tore apart the
supercontinent to create
the Americas, Africa, Eurasia.
And first Africa and
then India broke away
and headed back north again
and recollided with Eurasia.
And as Africa rode
north, it essentially
swallowed up this once
great ocean of the Tethys.
And all that remains
today is crammed
between Europe and Africa
as the Mediterranean Sea,
as this oval-shaped puddle
from that once vast ocean.
But specifically, what
is happening right now
is that Africa is being
subducted beneath the Eurasian
plate.
There's Africa that is
plunging down and being
melted and destroyed in
the fiery depths of Earth's
interior.
And that process has crumpled
up the northern Mediterranean
coastline.
It is riddled full of lots
of archipelagos, and islands,
and inlets, and coves, and bays.
And when the sea
level is high, like it
is at the moment
between the ice ages,
this creates a fantastically
intricate and complex coastline
full of natural harbors.
The north Mediterranean
is ideally
set up for seafaring
societies, like the Minoans,
the Phoenicians, the Greeks.
Whereas, the southern
half of the Mediterranean,
because of the African
continent being destroyed--
it is smooth, and
flat, and boring.
It is unaccommodating.
It doesn't provide
you natural harbors.
And about the only
exceptions throughout history
of great civilizations on the
other half of the Mediterranean
have been the
Egyptian civilization,
huddled around this
linear oasis of the Nile
flowing through the
desert, and Carthage,
which appeared up here where
there is a natural harbor,
and came to challenge even
the might of the Romans
before they lost and were
literally obliterated and wiped
off the face of the map
by the Roman Republic.
But other than those
two exceptions,
the southern
Mediterranean coastline
has been quiet and empty.
And again, that comes down to
these fundamental Earth-moving
processes of how
features of our planet
have dictated long themes and
long trends of our history.
If you bring the story-- so
I'm skipping over through quite
a few chapters of the book--
but if you bring the story up
to much more into the modern
age, into more recent history--
and I want to tell you the
story of how Europe spread out
to discover the world.
This map here is
slightly confusing,
because I want to show you the
geography of the seas instead
of the geography of the land.
So this is the Atlantic.
This is the Northwest
bulge of Africa.
There's Europe, at the top.
And then the peninsula-- the
Iberian Peninsula, with what
was to become the modern states
of Portugal and Spain there.
And for centuries, Europe
had been a backwater.
We were primitive.
We were left out.
We were right on the
outskirts of all the action
across Eurasia.
We were right on the
extremity of the silk roads
and all the exchange of trade,
and knowledge, and culture,
and ideas, and people.
We were primitive and
backwards, compared
to the rest of Eurasia.
And it was only with the
beginning of the 1400s
when Portuguese and
then Spanish sailors
turned in the
opposite direction.
They headed out into this
vast, stormy ocean that people
had just avoided for
good sense and had
been focusing themselves in
crossing the Mediterranean,
or maybe edging down the
African coast slightly.
But the Portuguese
sailors first started
heading out into the
Atlantic Ocean as a whole.
And the stepping stones
that drew them out
into this great ocean were the
Atlantic archipelagos-- islands
like Madeira, the Canary
Islands, the Azores.
And you can very
easily head down
from Europe along the North
African coast, following
the direction the prevailing
winds blow you anyway,
and the current's
already flowing.
That step is easy.
The Phoenicians had been doing
that for thousands of years.
But to get back home again in
a sailing ship is difficult.
You can't simply turn around
and go back the way you came,
because you'd be fighting
against the very winds
and currents that took you
there in the first place.
And so the realization,
that transformation point
in history, was when the
Portuguese captains realized
that, paradoxically,
to get home,
you head further out to
the depths of the ocean.
You complete what's
known as a volta
do mar, a return of the sea.
You turn out deeper
into the ocean
where you now encounter a
different pattern of winds
and currents, which allows
you to then turn back to home,
to the port that you came from.
And as they completed
a wider volta do mar
by heading further
down the African coast,
that loop took them
across the Azores.
And they discovered
those, as well.
They realized that to sail
around over large distances,
you have to hop back and forth
between different regions
of the wind system around the
planet and the ocean currents
that those blow around.
And since the 1400s,
we've pieced together
not just this little jigsaw
piece of the entire puzzle,
we now have the global view of
how Earth's atmosphere moves,
about where the winds come from.
And it's as simple as the
fact that, around the equator,
it's sunny.
It's warm.
The warm air rises, rolls
over through high altitude
before sinking back down
towards the ground again,
and then returns to the equator
as what we would call winds
across the surface.
And the only other important
fact is that while that great
big churning circulation current
is going on-- this is identical
to what happens over one
of your radiators at home--
the Earth is spinning.
It's turning beneath
that circulation current.
So you get the
Coriolis effect, which
deflects the winds heading
back towards the equator
to one side.
These are the trade winds.
They always blow
towards the west.
Columbus realized that all he
had to do was follow downwind,
and it would carry
him towards the West,
towards what he hoped
was China or Japan.
And he stumbled across,
instead, the Americas--
a continent that no
one had anticipated
would even be there.
To return home
again, you can't just
go back the way you came,
fighting the very winds that
took you there.
You hop north ever so
slightly to put yourself
into a different circulation
current of Earth's atmosphere,
which generate the westerly
winds that blow you very neatly
in the opposite direction.
There are these stripes
of wind bands blowing
in opposite directions around
the planet which serve very
effectively as conveyor belts.
You pop yourself in
one, flow downwind
to where you want to be.
pop up to the next one
to come back home again.
And it was that
fundamental realization
that you could predict
where the winds will
be at different places that
enabled us to explore around
the entire world, build
these great big trade
links across the
oceans, joining together
the continents in a way that
had never happened before.
This is the Portuguese route.
They completed their
exploration down
the African coast around
the southern tip of Africa
and eventually reached
India and the Spice Islands
they'd been striving
for all the time.
And by taking that
wide volta do mar
through the southern
Atlantic, you
ended up looping
around so far that they
stumbled across the coast
of Brazil, South America.
The reason that Brazil
speaks Portuguese,
not Spanish like the rest
of that entire continent,
is because these Portuguese
captains stumbled across it,
because that's the
way the wind blows you
when you're trying to get around
the southern tip of Africa.
The Spanish first,
with Columbus,
crossed the Atlantic, then
down around the south coast
of the Americas and
discovered a whole new sea--
the peaceful sea, the Pacific.
And they realized, conveniently,
that exactly the same patterns
of winds repeated there as well.
They built the longest
running sailing trade routes
of history, taking stuff
they bought off the Chinese--
the silk, incense, and
other luxury goods--
hopped up into the
westerly winds,
crossed the Pacific to
the coast of the Americas
and to California,
headed down the coast
to pick up the stuff
from the silver mines
that they were working, and then
back across the trade winds,
across the whole Pacific
to complete that loop.
And the reason, therefore,
that California,
historically-- the
reason it became
so important, and cities like
Los Angeles, and San Francisco,
and San Diego-- the
reason all that exists
is simply because that is the
only place the wind takes you
to when you've been
crossing the Pacific.
That's where it drops you off.
That's where you need to found
your cities and your colonies
to resupply the ships so they
can then head back further down
into the opposite wind band.
The Dutch, in the 1700s,
discovered a shortcut
across the Indian Ocean--
not going the long
way around the coast,
but cutting straight across
through a band of winds
called the Roaring Forties.
The westerly winds in
the southern hemisphere
don't encounter great continents
or mountain ranges that
act as walls to block the wind.
So the winds down there are
much, much fiercer, much
stronger.
There is literally a
motorway in the ocean
that you plop yourself into
and can easily halve the travel
time up into the Spice Islands.
Australia was discovered
by Dutch captains
nipping along that shortcut.
But you also need to know
when to take your turn off
from that motorway.
And the coral reefs off the
Western coast of Australia
are absolutely littered
with shipwrecks
from captains that
missed their turning.
They were bombing down
the Roaring Forties,
didn't turn north early
enough, and drove themselves
onto those coral reefs
and wrecked themselves.
And then finally, but
arguably most crucially,
the subsequent history.
The subsequent history was
the Atlantic trade triangle.
Manufactured goods were
taken from Britain,
from North Europe.
We were going through the
early stage of the Industrial
Revolution.
We're using machinery to
make things for ourselves,
rather than people.
And those textiles, those
cloths, the weapons,
were taken down the ancient
Portuguese route to West Africa
where they were
sold, and the ships
loaded up instead with
forced human labor--
slaves.
People were kidnapped,
forced onto the ships,
carried across the tradewinds
to the colonies in the Americas,
and not just in North America,
but also in Brazil and South
America, where they
were forced to work
on the plantations
around those colonies
growing plants like cotton, and
tobacco, and tea, and coffee.
And those raw materials, the
product of that slave labor,
was then loaded back into
ships and carried along
the westerly winds back
to Britain and Europe
where the cotton
fiber was turned
using the machines into the
textiles, which were then
taken back down to Africa.
So it was a very
neatly closed loop.
And with every turn
of that economic cog,
it generated huge
profits for its masters,
for the slave masters,
but fundamentally
blown around by those
patterns of circulation
in Earth's atmosphere.
It is simply the case that some
places are easy to sail to,
and others are difficult.
That's what dictates
where your trade routes emerge.
That's what dictates where your
trading posts, your colonies
have to be placed.
That dictated the pattern
of empire building,
the first of the Portuguese,
and the Spanish, and the Dutch,
and the French, and British.
And so in the early
stages of globalization,
the making of the modern
world that we are all
familiar with today,
it was fundamentally
the winds that created that
pattern that has determined
so much of the modern world.
The last example I
wanted to show you
was to bring things right
up to the modern age--
skipping through our origins
as a species and the emergence
of civilization,
through thousands
of years of these grand
themes of world history,
to show how you can see even the
fingerprint and the signature
of the planetry in the
political-- in political maps.
An example I want to show you
is the politics of this place,
of the southern
states of America.
And if we strip away
the satellite view
and instead show you
the political view,
the political map, this
is the voting behavior
in the last
presidential election.
This is the election that voted
Trump into the White House.
And unsurprisingly, the
southern states of America
are, on the whole,
staunch Republican.
There is a sea of red across
this whole continental region.
Some counties did vote
blue, voted the Democrats.
But curiously, these
Democrat-voting counties
aren't sprinkled randomly.
They're not peppered
across these states.
There is a very clear pattern
and structure to where counties
happened to vote the Democrats.
There's Democrat-voting
counties along the line
of the Mississippi.
This one stands out.
This is obvious.
But what is much,
much more curious
is this arc, this crescent
of Democrat-voting counties
that bears no relation to
anything on the ground.
This isn't along a river valley.
It's not along any particular
terrain in the world.
This is the topological
map of the same region.
This is the Mississippi River,
and then delta, down here.
The mountain range
here was crumpled up
in the previous cycle of
supercontinent building-- plate
tectonics, a whole chapter
before Pangaea and the last one
we spoke about.
These are the Appalachians.
And if instead of the terrain
I show you the geology,
the kind of rocks that
we have underground--
and I'll show you rocks which
are 70 million years old.
And they form in this
particular arc-shaped crescent
through the southern states.
These are rocks on the surface
which have been eroded down
which are 70 million years old.
And if I overlay on top of
that, again, the political map--
that correlation, that
correspondence is undeniable.
For some reason, people voted
for Hillary, rather than Trump
in the last election,
and indeed, any election
you care to look back, back
through to the Civil War,
voted for Democrat
if they happened
to have rocks beneath
their feet which
were 70 million years old.
Why on earth would that be?
These aren't geologists.
They're not digging
boreholes going,
hm, well, this is 60
million years old.
I'm a bit too early.
I'm going to have to vote Trump.
Ugh.
Why would that be?
And the story here is a
wonderfully fascinating
sequence of cause
and effect stretching
through centuries
of human history,
and then back through millions
of years of planetary history.
70 million years ago, when those
rocks were first laid down,
the Earth was in a chapter
of its history called
the Cretaceous.
The sea levels were very,
very high back then.
And the ocean flooded, swamped
right through continental North
America in a great
interior inland sea.
And it dumped what
was essentially
seafloor mud across a great big
area, which has been compacted
down, had other strata of
rock layered on top of it,
which has then been eroded back.
So this is the seafloor mud
which has been re-exposed here,
which produces a soil when
it's eroded and weathered
which is very dark, very
rich, full of nutrients,
very fertile.
In the early 1800s,
they realized
that that particular
soil is particularly
good for growing a cash crop
that people want to sell back
to Britain and Europe to make
some money for themselves--
for growing cotton.
Now unlike other crops,
like wheat or rice,
which are easy to harvest--
you just chop them off
in the field, take it
elsewhere, shake it a bit,
and your grain falls off.
With cotton, it's incredibly
finicky and fiddly
to pull off the bolus,
the ball of cotton fibers,
off the plant.
That means human fingers.
And in this period in history,
unfortunately and tragically,
that meant slave labor.
That meant people
had been abducted
in Africa, taken across
that Atlantic passage
that we saw in the
chapter about the winds,
forced to work on
those plantations.
And even hundreds of years
later, after the Civil War,
after emancipation,
freedom from slavery,
after the Civil Rights
movement, this crescent of 70
milliom-year-old rocks,
this Cretaceous region,
still has the highest density
of African-Americans living
there--
people that,
unfortunately, are still
afflicted with
socioeconomic problems,
of being generally poor, having
access to poor health care
or poor schooling, people that
would tend to vote, therefore,
for Democrats's promises and
ideals, rather than Republican.
And indeed, the town
that I've shown here--
sorry, the city of Montgomery--
this is where, in the
1950s, a black woman
called Rosa Parks
refused to give up
her seat to a white
gentleman on the bus--
the very event that triggered
the entire civil rights
movement, that transformed
American society in politics,
the very epicenter
was right there,
smack in the middle of that band
of 70 million year old rocks.
This is a whole chain of
causation through hundreds
of years of history
and then millions
of years of our planetary
past that explains
the politics we see even today.
And just to prove to
you that I've not cherry
picked the only example around
the world where that is true,
where that works, there's
another quick example
here closer to home.
This is Britain on the left.
And I've shown
the constituencies
in red that voted Labor in
the last general election
and, indeed, vote Labor in
pretty much any election you
care to look at.
These are the Labor heartlands.
On the right, I've shown
rocks beneath the ground which
are 320 million years old.
And again, there is an
astonishing correlation,
a correspondence between people
voting Labor and happening
to have rocks beneath
their feet which
are 320 million years old.
I won't go into the
reasons behind that.
Try to have a bit of a think.
But if I give you a
clue that the chapter
of Earth's history
320 million years
ago was the Carboniferous--
that is when the great
coal fields were laid down.
Something strange happened
in our planet's past
320 million years ago where
the planet's recycling system
broke down.
Trees thrived, and grew,
and died, and fell over,
and then would just not rot.
And it built up
these huge deposits
of peat and then coal, which
powered first Britain and then
the rest of Europe and the
world through Industrial
Revolution from that other
chapter of our planet's
history.
So I've just tried to pick out
some of the narratives, some
of the stories that I found
most fascinating and most awe
inspiring when I was researching
and writing for this book,
"Origins," about where we
came from as a species, how we
migrated around the entire
world, where civilizations
first emerged, how it
enabled us to explore around
the planet and globalize.
There are some other
examples I've thrown up here
from elsewhere in
the book, which
is basically the clickbait.
There's stories in
"Origins," in the book,
such as, why do most of
us eat a bowl of cereal
or a slice of toast
for breakfast?
There's a deep, planetary reason
why we eat these cereal crops.
There's a staple for
basically every single meal
of every single human
around the world.
There's a story about
why it was that Holland's
drowned landscape after
the end of the last ice age
helped create the
modern financial system.
So you can read up on any of
those in this book, as well.
I think some of
you who are lucky
have nabbed yourself
a free copy.
If any of you were not lucky
enough to grab a free copy,
you can pick it off
from any good bookshop.
It's still in hardback
at the moment.
And there's some other
books what I did.
My last one was "The
Knowledge," which
is this book about how
to reboot civilization
after an apocalypse,
as a way for exploring
the history of science
and technology again.
And I've written a few books
on my actual field of research,
which is in astrobiology
and the possibility of life
on other planets.
I spend my day job thinking
about hardy bacteria
and how they could survive
on the Martian surface
and, more importantly,
how we could detect
that they are there and looking
for so-called [INAUDIBLE]
using spectroscopic techniques.
So you can read up on that
sort of stuff, as well.
AUDIENCE: I wanted to ask
you about global warming.
So do you think that
it's a man-made process?
Or is it just how the
Earth is evolving?
And how do you think
is it affecting
the formation of land and
oceans that you just explained?
LEWIS DARTNELL: So the question
then was about global warming
and whether I believe it to
be human-driven or, I guess,
part of natural cycles.
And I would say there
is no shadow of a doubt
that global warming
is happening.
There is an increasing
concentration of carbon dioxide
in the atmosphere,
which is driving
increasing average
temperatures around the world.
And those are both being
caused by human activity--
by our industry, by our
shipping, by our factories,
by our cars.
And without getting too
apocalyptic about it all,
we are clearly facing a very
great challenge in our very
near-term future--
in the next years and decades.
And we need to start making some
difficult decisions about how
we respond to that challenge.
We're going to have to
change as a society,
rather than just individuals.
And there will be no
single technological fix
to this problem.
That is my belief.
I'm not a planetary scientist.
I'm an Earth
scientist, but that is
my understanding from talking
to a lot of colleagues who are.
In terms of what
effects that might
have on the grand
scale of things,
it will clearly affect us humans
and our civilization greatly.
But looking on the wider
scheme of planetary history,
as I've been doing
throughout this talk
and do throughout
the book, one effect
of this human-driven
global warming
is that we've probably already
canceled the next ice age.
Even if we were to stop all
carbon emissions tomorrow,
we've already pumped
out enough that,
when these Milankovitch cycles,
these cosmic cycles in Earth's
tilts and its orbit around
the sun next fall into sync--
that makes the
northern hemisphere
much colder, which would
have triggered an ice age.
It will not happen when those
Milankovitch cycles fall back
into sync again.
We've warmed the world already
too much for that to occur.
One could argue,
perhaps that would
be a good thing from
the human perspective.
If I go back to the map of the
world during the last ice age,
clearly, there are
huge challenges
we need to solve with sea
level rising, changing
in the climate, changing
the distribution of rainfall
and drought and
where we can grow
crops to feed 7 billion people.
But if we're looking thousands
of years in the future
and we have cities in
the northern hemisphere,
things get quite
tricky if there's
four kilometers of ice sheet
grinding over your cities.
So one could argue that maybe,
in the long term from a human
perspective alone, cancelling
the next ice age might be
a good thing.
Yeah?
AUDIENCE: As someone who
thinks about apocalypses
and the effect of the
Earth on humanity, what's
your opinion on human
civilization on other planets
in either the short-term,
Elon Musk style,
or even very, very long term?
LEWIS DARTNELL: Yeah, so the
last book, "The Knowledge,"
I wrote that there's
different ways
you could tell the same story.
I picked the apocalypse,
because I think everyone
loves "The Walking Dead".
And it was a neat little almost
kind of a cliche to latch onto.
Exactly the same story
could've been told--
you are launching
to another planet.
What is the minimum
set of civilization
you need to put in a
suitcase, put in a spacecraft,
and go with you?
And the Polynesians were doing
this thousands of years ago.
They had a set of plants
that provided everything they
needed for Polynesian society.
And they packed it into
a canoe and headed off
towards the horizon to colonize
all of the islands in the far
Pacific.
So it is a really
interesting question.
How could you have an outpost of
humanity, a colony of humanity
on another planet?
Mars would be the
natural choice,
after the moon, for putting
a permanent human presence.
However, having said
that, even under the best,
perfect conditions of a
midsummer lunchtime on Mars,
the conditions are
unrelentingly brutal,
compared to the South
Pole of the Earth.
It is punishingly cold,
very low atmosphere.
We can't even take certain
things for granted,
such as being able
to breathe the air
or have ready access
to lots of water.
You have to fight for everything
you need to survive on Mars.
And the problem
with space missions
is that you are severely
limited in the amount of mass
you can send somewhere.
So a lot of what's
being talked about
is called in situ
resource utilization.
How do you live off the
land when you get to Mars?
And some of the research
I've been doing links
into things such as, where can
you get water from on Mars?
How do you turn that water into
oxygen that you can breathe?
How can you perhaps have
life support systems
which are biological in their
nature, using things like algae
to grow by sunlight on Mars
to create the oxygen that you
need to breathe?
All of these things are
fascinating areas of research,
but we are not there yet in
terms of the delivery of those,
of actually having practical
applications and solutions
from them.
So I applaud Elon
Musk's efforts of trying
to get to Mars in the next
10, 15 years, or whatever
number he's put on it.
I do not think we will have
a human presence on Mars
in 10, 15 years.
I would be surprised if we
have the first return mission
to Mars in 10, 15 years.
And personally, I
would argue that we
should be spending more
time practicing on the moon
where, if something goes wrong,
you're a day or two's flight
back to the Earth.
If something goes
wrong on Mars, you're
six months, eight months,
a year away from help.
It is an order of magnitude
different proposition
for putting people on Mars,
and then supporting them
on Mars as well.
AUDIENCE: Hi.
For reasons that should
become obvious from my accent,
can you go back to your
southern American states?
LEWIS DARTNELL: Are
you, perchance--
AUDIENCE: Yeah.
LEWIS DARTNELL: --from--
AUDIENCE: I am.
[LAUGHTER]
LEWIS DARTNELL:
Can I ask, did you
have rocks that were
70 million years old?
AUDIENCE: I've got an
interesting observation
from your slide.
LEWIS DARTNELL: This one?
AUDIENCE: You'll see
in Alabama that there's
one outlier that's outside
the [? Cretaceous ?] Belt--
major outlier that's above
it there, to the north.
LEWIS DARTNELL: Do
you mean this bit?
AUDIENCE: No, no.
To the north of the--
LEWIS DARTNELL: That belt?
AUDIENCE: That's Georgia.
Alabama is more to your--
SPEAKER: This one, here?
AUDIENCE: Yeah, that--
SPEAKER: That one?
AUDIENCE: No, no, farther down.
[LAUGHTER]
No, no, no.
Farther south, right.
It's south.
There you go, that one, which
is outside the [? Cretaceous ?]
belt.
SPEAKER: He didn't
study geography.
AUDIENCE: That's
Birmingham, Alabama.
That's where I'm from.
That one is different
from the others.
And it's a great
confirmation of your theory.
And I was wondering
if you know about it.
LEWIS DARTNELL: For the sake
of your own dramatic delivery,
of course I know, but I
think for everyone else--
AUDIENCE: It's such a wonderful
confirmation of your theory.
That's Birmingham.
Birmingham is a
turn-of-the-century industrial
city.
And it's the last mountain
in the Appalachians--
is Red Mountain in
Birmingham, Alabama.
Because of that, it is
the only place on Earth
that has the three elements
you need to make steel.
And after slavery,
people basically
enslaved in a
post-slavery slavery
in Birmingham, working the coal
mines-- black people worked
the coal mines.
Because of that, Birmingham is
the only majority black major
city in Alabama.
And that's the reason it's blue.
LEWIS DARTNELL:
That is fascinating.
Thank you.
AUDIENCE: Yeah.
Sorry.
LEWIS DARTNELL: There's another
really interesting story
about the Appalachians and
the availability of coal
which is suitable for smelting
iron and then creating steel
and how that held back the
adoption of the Industrial
Revolution in the States--
in America, at the time--
compared to Europe, which
is also in the book.
SPEAKER: And we've got one here.
AUDIENCE: Thank
you for your talk.
I was wondering if
you could touch on,
or perhaps if your
book touches on,
when you look at a satellite
map of Earth at night
and you realize the majority
of the most populated cities
are above the equator, in
the Northern Hemisphere.
There you go.
Wow, you got that ready to go.
[LAUGHTER]
And I was wondering if you--
LEWIS DARTNELL:
[INAUDIBLE],, yeah?
AUDIENCE: --could touch on
why a majority of the cities
are above the
equator, and perhaps
if the shape of continents
had anything to do with it.
LEWIS DARTNELL: So I
joke, but you basically
spiked the perfect plant
question from the audience,
because that is exactly what I
talk in the very final chapter
of the book, of the code
where I bring together
all the threads, more,
10 different chapters
into one map.
This is artificial
illumination around the world.
So it's basically
a heat map, if you
like, of humans, or
at least humans living
in dense urbanizations.
And there are some
really nice patterns
that, again, just jump out
at you when you look at where
we are around the world today.
Equatorial regions tend to be
relatively sparsely populated.
There's dense forest there.
It's hard to put a city in
the middle of the Amazon.
Around 30 degrees
north or south,
when that great big circulation
of the Earth's atmosphere
descends back to the ground,
the air is very, very dry.
That is where the great deserts
of the planet are always found.
The Sahara is not
densely populated.
The interior desert of Australia
is not densely populated.
But the places where we
do see dense population
are interesting in
their own right.
You can see things
like the Nile Valley,
the Indus Valley just burningly
bright in these otherwise arid
parts of the world.
The band of lights
you can see here--
that is the old
Steppes Belt. That
is like the prairies
of Eurasia--
these great grasslands,
which had a defining role
in Eurasian history
for thousands of years
because, out of the
steppes, these horse people
would repeatedly emerge.
It was the Huns that collapsed
the Western Roman Empire.
The Mongolians came
out of the steppes.
And there's this
great tension between
the nomadic pastoralists
of the steppes region
and all the civilizations
around the margins of Eurasia.
The Great Wall of China
was a defensive wall,
but fundamentally it
follows an ecological line
between dry places with only
grasslands, and therefore
horse people, and
wetter parts where
you can grow crops, and
therefore have cities.
Those steppes have
since been dug up
with mechanized agriculture
and artificial fertilizer
and now are some of the
most productive wheat
fields on the planet.
The slightly thinner
line down here-- that's
the route of the old silk roads.
It's like a string of
pearls, a string of cities
strung along the silk roads and
going around the northern part
of the Himalayas.
So there's some
really nice patterns
you can pull out of just looking
where people are active today,
and how that's been created
through thousands of years
of world history,
and how the planet
has had the
determining influence
behind those thousands of
years of world history.
AUDIENCE: Yeah, I
was wondering if you
were able to find other
patterns in the US
by controlling for
gerrymandering.
[LAUGHTER]
AUDIENCE: And
well, in that area,
it's probably something
that would be valuable.
LEWIS DARTNELL: It's not
something I have done.
I agree, it's
something that would
be very interesting to look at.
I wonder if gerrymandering is
essentially smudging out what
might have been a
good signal otherwise,
because that's one
political party trying
to get the upper hand
by fiddling where
the distribution of people is.
AUDIENCE: Right.
Well, usually, it would look
like something like there,
like putting all the Democrats
in one tiny little thing.
So yeah, it might make it clear.
LEWIS DARTNELL:
Might polarize what
would have been an otherwise
smoother distribution.
Thank you.
SPEAKER: With that,
please join me
in a round of applause
for Lewis Dartnell.
[APPLAUSE]
LEWIS DARTNELL: Thank you.
