phu đề video history of word in two hour

8/13/2019 Phu video History of Word in two hour

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00:00:01 What if we could tell you everything, the entire history of the world?

00:00:07 Now, what if we told you, we could do it in just two hours?

00:00:12 We're going to tell the whole story, from the Big Bang to the present day.

00:00:18 How the planet prepared, for the rise of man.

00:00:22 How the Stone Age, led to the steam engine.

00:00:27 How the first seeds sprouted, into cities and civilizations.

00:00:33 Everything is connected, and the path leads to you.

00:00:39 lt took history 1 3.7 billion years to unfold.

00:00:43 We'll show you everything you, need to know in the next two hours.

00:01:06 This is our infant universe.

00:01:09 Everything that will ever exist,everything that will ever happen,

00:01:14 all begins here, within this tiny bundle of energy,smaller than an atom.

00:01:23 And right now, history as we know it is about to mysteriously begin.

00:01:30 For reasons we may never know,our universe suddenly erupts.

00:01:45 ln a millionth of a millionth, of a millionth of a millionth

00:01:49 of a millionth, of a millionth of a second,

00:01:52 it went from a size, smaller than an atom

00:01:55 to bigger than a galaxy.

00:02:04 What you're seeing is energy,

00:02:07 and it's one key to understanding, everything that will unfold in the next two hours.

00:02:14 Within a fraction of a second, the Big Bang creates, all the energy that will ever exist,

00:02:21 all the energy that will power the stars,

00:02:24 that will fuel, anything that ever lives.

00:02:28 All the energy, that you will ever consume

00:02:31 dates back to the beginning of time. When you put gas into your car,

00:02:40 you're tapping energy, that was created during the Big Bang.

00:02:46 You're tapping, the energy of the universe itself.

00:02:58 We're only a few minutes into our two-hourjourney,but already 380,000 years havepassed. You are about to witness the birth of your original ancestors, the first atoms.

00:03:20 This is hydrogen.

00:03:23 The universe will use it to make


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everything in the world around us.

00:03:27

00:03:29 Hydrogen is like a baseball team.

00:03:31

00:03:32 You say, "What player do l want

to start my team with?"

00:03:34

00:03:34 Well, if l want to start a universe,

l want to start it with hydrogen.

00:03:37

00:03:37 Because from that, with a lot of heat

and a lot of pressure,

00:03:39

00:03:39 you can build more kinds of atoms.

00:03:41

00:03:43 The first atoms

blast through the early universe.

00:03:46

00:03:49 And luckily for us,

they don't spread out evenly,

00:03:52

00:03:54 because in those tiny pockets

with more atoms,

00:03:57

00:03:57 gravity, the great sculptor

of the early universe,

00:04:01

00:04:01 begins to work its magic.

00:04:03

00:04:10 The first galaxies


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are beginning to form,

00:04:13

00:04:14 revealing a timeless secret

of the universe.

00:04:17

00:04:23 Throughout history,

00:04:24

00:04:24 whenever more matter and energy

can be drawn together in one place,

00:04:28

00:04:28 more complex things can emerge.

00:04:31

00:04:32 We have all of these urban centers

around the planet

00:04:36

00:04:36 where so much creativity, so much art,

so much science,

00:04:40

00:04:40 so much culture came about

00:04:42

00:04:43 because of all these opportunities for

things to interact with each other.

00:04:46

00:04:47 Really, in a sense, where

there is stuff, new stuff can develop.

00:04:51

00:04:51 And where there isn't anything,

nothing much can develop.

00:04:54

00:05:01 300 million years after the Big Bang,


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00:05:04

00:05:05 inside of forming galaxies,

00:05:08

00:05:09 gravity continues to squeeze together

clouds of gas and dust,

00:05:13

00:05:14 causing pressure and heat

to violently rise.

00:05:17

00:05:21 When the temperature reaches

1 8 million degrees Fahrenheit,

00:05:25

00:05:25 hydrogen atoms slam together,

creating a new element, helium,

00:05:30

00:05:30 and radiating bursts of energy.

00:05:32

00:05:34 The first stars are born.

00:05:37

00:05:39 Suddenly there were

these new beacons of light

00:05:42

00:05:42 shining forth,

pouring energy into the universe.

00:05:46

00:05:48 Let there be light.

00:05:49

00:05:51 But something is missing

from this early universe.

00:05:54


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00:05:54 There are billions of stars,

yet not a single planet.

00:05:58

00:05:59 To form planets and eventually people,

00:06:03

00:06:03 to take the next leap that would

make all of history possible,

00:06:06

00:06:07 the universe needs more to work with

than just hydrogen and helium.

00:06:11

00:06:12 The complicated elements,

00:06:14

00:06:14 the heavier things

that we build stuff out of,

00:06:16

00:06:16 for example, iron or life built out

of carbon and things like that,

00:06:21

00:06:21 they're actually

manufactured in stars.

00:06:23

00:06:23 We may see stars like our own sun

as sources of light,

00:06:27

00:06:27 but there is something bigger

happening deep inside.

00:06:31

00:06:31 Stars are element factories.

00:06:34


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00:06:34 They fuse hydrogen into helium,

helium into lithium,

00:06:38

00:06:38 forging 25 of the most common elements

we'll need to live,

00:06:42

00:06:42 including carbon, oxygen,

nitrogen, and iron.

00:06:46

00:06:48 So more than 1 2 billion years ago,

00:06:51

00:06:51 stars are already creating the element

that will spur the lron Age,

00:06:56

00:06:56 allow for the building of cities

00:06:59

00:06:59 and the creation of some of mankind's

most famous monuments.

00:07:03

00:07:08 But a look at the Statue of Liberty

00:07:10

00:07:10 reveals the next challenge

awaiting the early universe.

00:07:13

00:07:14 While the statue's frame is iron,

00:07:17

00:07:17 her skin requires an element

too heavy to be made in stars.

00:07:21

00:07:27 For Lady Liberty to have


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material for her skin,

00:07:30

00:07:32 for there to be

gold for wedding rings,

00:07:35

00:07:36 or uranium for nuclear reactors,

00:07:39

00:07:39 some elements had

to be created another way.

00:07:42

00:07:42 Stars don't have

enough energy to do the job,

00:07:45

00:07:46 but if the element factory

isn't powerful enough,

00:07:49

00:07:49 how about blowing up the factory?

00:07:52

00:07:56 Just a few million years

after the first stars formed,

00:07:59

00:07:59 some of them exploded.

00:08:01

00:08:02 These explosions, known as supernovas,

00:08:06

00:08:06 are the biggest blasts in the universe

since the Big Bang,

00:08:09

00:08:09 providing the extra boost of energy

needed to fuse heavier elements.


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00:09:09

00:09:10 Copper and tin, Bronze Age.

00:09:12

00:09:12 Without supernovas,

there's no Bronze Age.

00:09:15

00:09:16 Go to any supermarket

and buy a multivitamin

00:09:17

00:09:19 and go and look in the ingredients.

00:09:20

00:09:20 You'll find copper. You'll find zinc.

You'll find selenium.

00:09:23

00:09:23 You'll find all sorts of elements

that can only be made in a supernova.

00:09:28

00:09:29 The elements made by stars

will become the seeds of life on Earth

00:09:34

00:09:34 and the drivers of human history.

00:09:37

00:09:38 But the journey has just begun.

00:09:40

00:09:41 Before there can be life, the universe

has to build us a suitable home.

00:09:47

00:09:49 To build a proper house, you have to

assemble the right materials

00:09:53


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00:09:53 all in one place.

00:09:55

00:09:57 Now when planets form,

it's the same thing,

00:10:00

00:10:00 it's the materials

that you have at hand

00:10:03

00:10:03 that's gonna dictate the kind of house

that your planet's gonna be.

00:10:06

00:10:07 To get enough of the right material

in the right place all at once

00:10:11

00:10:11 takes a very long time.

00:10:14

00:10:14 Over the next eight billion years,

00:10:17

00:10:17 more than half of history

as we know it,

00:10:19

00:10:19 the element factories

continue their work.

00:10:22

00:10:23 Stars explode and are reborn,

00:10:27

00:10:30 each generation with

more heavy elements than the last.

00:10:33

00:10:37 Until 4.6 billion years ago.


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00:10:40

00:10:41 Finally there are

enough materials gathered

00:10:44

00:10:44 for the next step on the path to us.

00:10:47

00:10:53 A new star is born.

00:10:55

00:10:56 This is our sun.

00:10:58

00:10:58 lt's so massive that it's gathered up

00:11:00

00:11:00 99.9% of the gas and dust

in the solar system,

00:11:04

00:11:05 but there's still

just enough left behind

00:11:07

00:11:07 for gravity to build

some other things,

00:11:10

00:11:10 like planets.

00:11:12

00:11:13 The third one out from this star

will be our home.

00:11:16

00:11:19 By the time Earth emerges just over

four and a half billion years ago,

00:11:23

00:11:23 two-thirds of the history


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of the universe has already passed.

00:11:27

00:11:31 The first sunrises sweep

across a foreboding alien planet,

00:11:36

00:11:37 a world spinning so rapidly

that a day lasts only six hours.

00:11:41

00:11:45 When you go back to the early Earth,

right after the planet formed,

00:11:49

00:11:50 you really have to think

of the Earth as another planet.

00:11:53

00:11:54 The sun would have looked out

over a hellacious scene

00:11:57

00:11:59 ofjust molten lava.

00:12:00

00:12:04 And in places you would

see rafts of black volcanic rock.

00:12:09

00:12:11 Within the liquefied rock

the elements are all in a jumble.

00:12:15

00:12:16 Something has to

bring order out of this chaos.

00:12:20

00:12:20 And once again

that something is gravity.


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00:12:23

00:12:25 Lighter material

drifts toward the surface

00:12:28

00:12:28 and forms a solid crust,

00:12:30

00:12:33 while heavier material

sinks toward the center,

00:12:36

00:12:36 forming a molten iron-nickel core.

00:12:39

00:12:40 This churning liquid metal

00:12:42

00:12:42 creates a magnetic field

that reaches out into space.

00:12:45

00:12:46 Like a force field,

it will protect our future home

00:12:49

00:12:49 from the sun's

deadly charged particles.

00:12:52

00:12:52 Soon this magnetic field

will allow for life to grow,

00:12:56

00:12:56 and later, guide the explorers who

will connect two halves of the world.

00:13:00

00:13:01 But for all this to unfold, the Earth

will need a critical partner.


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00:13:06

00:13:14 Four and a half billion years ago,

00:13:16

00:13:17 an object the size of Mars

smashes into the planet

00:13:20

00:13:20 at 25,000 miles per hour.

00:13:23

00:13:29 Earth swallows up

much of the impactor.

00:13:31

00:13:39 But a spray of molten debris

is whipped off into space.

00:13:43

00:13:44 Within as little as a year,

gravity gathers this debris

00:13:48

00:13:48 into a secondary sphere

in orbit around the Earth,

00:13:51

00:13:52 where it has been ever since.

00:13:54

00:13:57 The formation of the moon

00:13:58

00:13:58 was an incredibly important event

in Earth's history.

00:14:01

00:14:02 And in fact, its creation,

over four billion years ago,

00:14:03


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00:14:06 is really important to

the Earth's climate today.

00:14:08

00:14:08 The moon keeps Earth steady.

00:14:11

00:14:11 lts gravitational pull

prevents the planet from wobbling,

00:14:15

00:14:15 saving us from wild climate swings.

00:14:18

00:14:18 And the collision that formed the moon

leaves Earth tilted on its axis,

00:14:23

00:14:24 giving the planet

a key ingredient to life,

00:14:26

00:14:27 seasons.

00:14:29

00:14:32 Having seasons is very, very important

00:14:34

00:14:34 for the evolution of life

on the Earth,

00:14:36

00:14:36 and having some stability

in the tilt of those axes,

00:14:40

00:14:40 that's very, very important also

for maintaining life on the Earth.

00:14:43

00:14:46 The moon's gravity


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also begins to slow Earth's rotation,

00:14:51

00:14:51 which will eventually lengthen

our days from six hours to 24.

00:14:57

00:15:07 4.4 billion years ago.

00:15:10

00:15:11 lt's too hot on Earth

for liquid water to exist,

00:15:15

00:15:15 but there's water vapor,

steam in the atmosphere.

00:15:19

00:15:21 The trick is

how to get it out of the sky.

00:15:24

00:15:24 Onto any world where you hope

to have life, a little rain must fall.

00:15:29

00:15:36 For millions of years

as the planet cools, rain pours down,

00:15:41

00:15:41 forming puddles, lakes,

and eventually our oceans.

00:15:47

00:15:50 By 3.8 billion years ago,

00:15:53

00:15:53 our planet has a moon

and permanent oceans,

00:15:57


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00:15:57 but it hardly resembles

the place we now call home.

00:16:00

00:16:02 To become the stage

for all of human history,

00:16:05

00:16:05 Earth needs an oxygen-rich atmosphere,

00:16:08

00:16:08 fertile continents

for people to discover and develop.

00:16:12

00:16:12 Who will create our modern world?

00:16:15

00:16:15 There's a trillion of them

crawling on your skin right now.

00:16:19

00:16:28 We're telling the history of the world

in two hours,

00:16:31

00:16:31 from the Big Bang to the present day.

00:16:35

00:16:35 And our modern world

holds important clues to the story.

00:16:39

00:16:39 ln fact, structures like this

00:16:42

00:16:42 hide a mysterious link

to the first life on Earth.

00:16:46

00:16:53 3.8 billion years ago,


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00:16:55

00:16:57 beneath the surface

of our primeval oceans,

00:17:00

00:17:02 a revolution is taking place.

00:17:05

00:17:09 Six simple elements,

including hydrogen from the Big Bang,

00:17:13

00:17:13 and oxygen, carbon,

and nitrogen created by stars,

00:17:17

00:17:17 have combined

to form the key substances

00:17:19

00:17:19 that will make up all life,

including us.

00:17:23

00:17:26 The most spectacular is DNA.

00:17:29

00:17:31 Within its spirals

hide the secret codes of life.

00:17:34

00:17:37 700,000 years

after the planet first formed,

00:17:41

00:17:42 life on Earth begins.

00:17:44

00:17:46 We stand

not on the shoulders of giants,


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00:17:49

00:17:49 but of tiny organisms, bacteria.

00:17:52

00:17:55 We're very egocentric. We think

that we animals run the world,

00:17:59

00:17:59 but in fact we are very late entrants.

00:18:02

00:18:03 lt was an empire of bacteria

long before animals.

00:18:06

00:18:06 Animals come along,

00:18:07

00:18:07 and we like to think

that we wiped out that empire.

00:18:11

00:18:11 Well, we would be dead

if we wiped out that empire.

00:18:14

00:18:15 l have within me

an entire zoo of bacteria.

00:18:18

00:18:19 ln fact, each one of us

00:18:21

00:18:21 has more bacteria living in our bodies

than there are people on the planet.

00:18:26

00:18:28 For billions of years,

00:18:30

00:18:30 microbes like these


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will have Earth to themselves.

00:18:34

00:18:36 Like our infant universe,

00:18:38

00:18:38 the first life is small, simple,

and full of possibilities.

00:18:43

00:18:44 The secret of how it explodes

00:18:45

00:18:45 into all of the incredible forms

we see today, including us,

00:18:50

00:18:50 goes back to the beginning of time.

00:18:52

00:18:53 As we've seen,

00:18:54

00:18:54 all the energy that will ever exist

was created in the Big Bang.

00:18:58

00:19:00 All creatures need to grab their share

of this energy to survive.

00:19:05

00:19:05 The more we harness,

the more efficiently we use it,

00:19:09

00:19:09 the more complex we can become.

00:19:11

00:19:12 And almost all of our share

of the Big Bang's energy

00:19:15


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00:19:15 is beamed to us by the sun.

00:19:18

00:19:21 Two and a half billion years ago,

00:19:23

00:19:24 some very special bacteria

00:19:26

00:19:26 figure out how to

consume the sun's energy to live.

00:19:30

00:19:32 ln doing this, they also create

00:19:34

00:19:35 the most important waste product

in the history of the world,

00:19:38

00:19:40 oxygen.

00:19:42

00:19:45 Soon, oxygen will remake our world,

00:19:47

00:19:48 but first,

it has another important job to do.

00:19:51

00:19:53 Earth's ancient seas

are full of iron particles,

00:19:56

00:19:56 and everyone knows

what happens when oxygen meets iron.

00:20:01

00:20:03 Here l'm a little bacterium.

l've produced this oxygen molecule,

00:20:06


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00:20:06 and here's a big piece

of iron and clump, l rust it.

00:20:09

00:20:12 The rusted iron

collects on the sea floor.

00:20:14

00:20:17 Billions of years later,

these huge deposits will be raised up

00:20:22

00:20:22 to become major sources

of the world's iron and steel.

00:20:26

00:20:30 lt was these iron deposits

00:20:31

00:20:31 that later on

drove the lndustrial Revolution.

00:20:34

00:20:36 ln this way, the Brooklyn Bridge

00:20:38

00:20:39 and the other early landmarks

of the lndustrial Age

00:20:42

00:20:42 are a direct link to

some of the first life forms on Earth.

00:20:46

00:20:49 Once there's no more iron

left in the sea to rust,

00:20:52

00:20:52 these ancient bacteria

have a mission to complete.


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00:20:56

00:20:56 They create so much oxygen

00:20:59

00:20:59 that it fills the oceans

and escapes into the atmosphere.

00:21:04

00:21:06 And from then on

we have a very different planet

00:21:09

00:21:09 from all the other planets

in the solar system.

00:21:11

00:21:12 Now, life takes a giant leap.

00:21:14

00:21:15 For the first time,

some bacteria learn to live on oxygen.

00:21:19

00:21:21 Every human breath is a ritual

two and a half billion years old.

00:21:26

00:21:29 Life tends to stick with what works

00:21:30

00:21:32 even over the course of

billions of years.

00:21:33

00:21:34 Oxygen is a game changer.

00:21:36

00:21:36 By taming its power,

00:21:38

00:21:38 life has found


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a better way to energize itself.

00:21:41

00:21:41 Twenty times more efficient

than anything used on Earth before.

00:21:45

00:21:46 What life does

with all this new energy

00:21:49

00:21:49 will be the story that leads to us.

00:21:51

00:21:58 Over the next two billion years,

life becomes more complex.

00:22:02

00:22:05 Skies become blue,

00:22:07

00:22:08 and so do the oceans

that reflect them.

00:22:11

00:22:12 Large, solid continents appear.

00:22:15

00:22:15 Earth is beginning to look

more like the place we now call home.

00:22:19

00:22:28 550 million years ago,

00:22:30

00:22:31 as the planet celebrates

its four billionth birthday,

00:22:35

00:22:36 oxygen levels in the atmosphere have

risen from next to nothing


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00:22:39

00:22:40 to as much as 1 3%.

00:22:42

00:22:44 Take a deep breath,

00:22:46

00:22:46 because life on Earth

is about to go wild.

00:22:49

00:22:55 This is the Cambrian explosion,

biology's version of the Big Bang.

00:23:00

00:23:02 Right after you have abundant oxygen,

you get size and complexity.

00:23:05

00:23:07 And oxygen lets you do that.

00:23:10

00:23:13 lt's in this breathtaking span

of roughly 30 million years

00:23:17

00:23:17 that most of the

major animal groups evolve.

00:23:20

00:23:22 By 500 million years ago, the first

bony fish have evolved in the seas.

00:23:28

00:23:29 These fish are our direct ancestors.

00:23:31

00:23:32 Though they look nothing like us,

00:23:34

00:23:34 they evolve the body parts that will


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make our own bodies possible,

00:23:38

00:23:38 including a spine,

and a mouth with jaws and teeth.

00:23:42

00:23:44 We owe a great deal

to our fish ancestors.

00:23:46

00:23:46 ln fact, all vertebrates today

00:23:47

00:23:47 really represent modifications

of the original fish body plan.

00:23:50

00:23:53 For the first four billion years

of Earth's history,

00:23:56

00:23:56 plants and animals

have stuck to the seas.

00:23:59

00:24:02 But that all begins to change.

00:24:04

00:24:04 With oxygen comes an ozone layer,

00:24:07

00:24:07 protecting us from

dangerous radiation.

00:24:10

00:24:13 Plants make the move first.

00:24:15

00:24:25 Around 400 million years ago,

animals are ready to take the leap.


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00:24:30

00:24:32 Among the first ashore

are the amphibians,

00:24:35

00:24:35 whose descendants will include us.

00:24:38

00:24:39 The most amazing thing about animal

evolution ever, for me personally,

00:24:42

00:24:44 is that moment that first amphibian

00:24:46

00:24:46 walks out of the primeval ocean

onto land

00:24:50

00:24:50 and takes a big gulp of air.

00:24:52

00:24:54 Kind of like great-great-great-

great-great-great grandpa

00:24:57

00:24:57 coming out of the ocean

and seeing this fantastic world.

00:25:01

00:25:03 And it's like, "Hey! l can live here.

00:25:05

00:25:05 "Look at those trees.

Look at those bugs.

00:25:06

00:25:06 "There's food here. l can do this."

00:25:08

00:25:14 Eventually, humans will conquer


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every imaginable terrain.

00:25:18

00:25:21 But before we can do that,

00:25:23

00:25:23 our ancestors must first cut their

final tie to the water,

00:25:27

00:25:28 mating season.

00:25:29

00:25:33 Like modern frogs,

00:25:35

00:25:35 they have jelly-like eggs

that would dry out on land.

00:25:38

00:25:41 But some amphibians

eventually solve the problem.

00:25:44

00:25:45 They evolve a new form of egg

00:25:47

00:25:48 with a shell

that keeps the moisture in.

00:25:50

00:25:51 This allows us

to carry the ocean with us onto land

00:25:55

00:25:56 and signals the evolution

of amphibians into reptiles.

00:26:01

00:26:01 You could be 300, 400, 500,

1 ,000 miles away from water


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00:26:06

00:26:06 and still have the water in that egg

in order to birth.

00:26:09

00:26:10 That is the key.

00:26:11

00:26:12 lt cuts that final tie to the ocean.

00:26:15

00:26:16 That way we could colonize

the rest of the land.

00:26:19

00:26:33 300 million years ago, life flourishes

in massive tropical swamps

00:26:40

00:26:40 where planet Earth

is cooking up a surprise.

00:26:43

00:26:44 As plants die here,

00:26:46

00:26:47 they are buried, compacted,

and cooked.

00:26:52

00:26:53 Energy created in the Big Bang

00:26:55

00:26:55 and radiated by the sun

to plants on Earth

00:26:59

00:27:00 is now locked away underground

as coal,

00:27:05


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00:27:05 a gift to be opened by human beings

millions of years in the future.

00:27:10

00:27:19 250 million years ago,

00:27:21

00:27:23 an apocalypse unfolds.

00:27:25

00:27:26 The biggest spike in volcanic activity

since the early days of the planet.

00:27:31

00:27:32 The atmosphere is choked

with carbon dioxide,

00:27:36

00:27:36 and the diversity of animal life

spawned in the Cambrian explosion

00:27:40

00:27:40 is stopped dead in its tracks.

00:27:42

00:27:46 More than 70% of all species on Earth

go extinct

00:27:50

00:27:50 in the worst mass die-off in history,

the Permian extinction.

00:27:55

00:27:58 Extinction is a recurring character

in the story of planet Earth.

00:28:02

00:28:04 Five times

in the last 500 million years,

00:28:07


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00:28:07 some cataclysm

wiped out the dominant species.

00:28:11

00:28:12 lt's a reshuffling of the deck that

allows new creatures to take hold.

00:28:16

00:28:17 New creatures like the dinosaurs.

00:28:21

00:28:24 Dinosaurs will reign

for the next 1 60 million years.

00:28:28

00:28:30 During that time,

the first hardwood forests appear.

00:28:34

00:28:36 And after

more than four billion years,

00:28:39

00:28:39 the moon's gravity finally settles

Earth into a 24-hour day.

00:28:44

00:28:47 At the start of the dinosaur era,

00:28:48

00:28:49 the continents are clustered together

00:28:51

00:28:51 into a single landmass

we call Pangaea.

00:28:53

00:28:54 But now they start to break apart.

00:28:57

00:29:00 Africa separates from South America.


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00:29:03

00:29:04 The vast Atlantic Ocean opens up,

00:29:06

00:29:07 creating what will become one of the

defining barriers of human history,

00:29:11

00:29:12 the gulf

between the old and new worlds.

00:29:15

00:29:19 The undisputed stars

of the dinosaur era

00:29:21

00:29:21 are animals like Triceratops

and T-Rex.

00:29:25

00:29:25 But there are some important creatures

scurrying around their feet.

00:29:29

00:29:30 lf we were to trace our lineage back

far enough,

00:29:33

00:29:33 we would come to really small

shrew-like mammals

00:29:37

00:29:37 surrounded by

these titans of reptile life.

00:29:40

00:29:41 During that time, mammals,

we were living on the fringes.

00:29:44


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00:29:44 We were maybe stealing dinosaur eggs,

maybe just eking out an existence.

00:29:49

00:29:49 So the dinosaurs kind of held us back.

00:29:52

00:29:53 The biggest headline of the history

of dinosaurs,

00:29:56

00:29:56 which is 1 60 million years,

is that we lost!

00:29:59

00:30:00 Mammals lost.

00:30:01

00:30:02 We couldn't get much bigger

than a small cat.

00:30:05

00:30:05 For 1 60 million years,

all the medium-size, medium-big,

00:30:09

00:30:09 big, gigantic and stupendous animals

were dinosaurs, for that whole time!

00:30:14

00:30:15 They beat us fair and square.

00:30:18

00:30:20 But the deck

is about to be reshuffled.

00:30:23

00:30:32 Sixty-five million years ago,

00:30:34

00:30:34 a six-mile wide object,


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likely an asteroid,

00:30:38

00:30:38 slams into the Earth.

00:30:40

00:30:48 A dust cloud blocks out the sun.

00:30:51

00:30:51 Temperatures plummet.

00:30:53

00:30:54 Every creature on land

weighing over 50 pounds goes extinct.

00:30:58

00:31:00 The reign of the dinosaurs is over.

00:31:03

00:31:05 The greatest gift that the dinosaurs

ever gave us was dying.

00:31:09

00:31:10 When they went extinct,

it gave the mammals time to rise.

00:31:14

00:31:16 lt doesn't take long after

the disappearance of the dinosaurs

00:31:19

00:31:19 for the first true primates to appear.

00:31:22

00:31:23 Like their later versions,

including us,

00:31:26

00:31:26 these mammals have evolved

forward-facing eyes

00:31:29


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00:31:29 allowing for accurate depth perception

and flexible hands with five digits.

00:31:35

00:31:35 They have five fingers, just like us,

which means we can grasp things.

00:31:40

00:31:40 lf you think about other animals

that don't have digits

00:31:42

00:31:44 organized the way ours are,

their ability to hold things,

00:31:46

00:31:46 to manipulate objects,

is much more limited.

00:31:49

00:31:52 Fifty million years ago,

00:31:54

00:31:54 our primate ancestors are evolving

on a planet that is warming.

00:31:58

00:31:59 lt's so hot,

there are jungles at the poles.

00:32:02

00:32:05 As the continents drift,

00:32:07

00:32:07 the Americas and Africa

have almost fully taken shape.

00:32:10

00:32:12 But in northern Africa,

00:32:13


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00:32:14 modern-day Egypt

is submerged beneath an ancient sea.

00:32:17

00:32:19 On the floor of that sea live small,

shelled creatures called nummulites.

00:32:24

00:32:24 Their shells,

made of calcium and carbon,

00:32:26

00:32:26 pile up on the sea bottom

over millions of years,

00:32:29

00:32:29 where they form into limestone.

00:32:32

00:32:33 Limestone that will be used

to build the Great Pyramids.

00:32:36

00:32:37 lf you look closely

at the pyramids today,

00:32:39

00:32:40 you can still see evidence that

these 4,000-year-old monuments

00:32:43

00:32:43 are in fact made of

50-million-year-old seashells.

00:32:48

00:32:56 By 1 0 million years ago,

00:32:58

00:32:58 Earth is morphing into a world

most of us would recognize.


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00:33:02

00:33:02 The Colorado River

is carving out the Grand Canyon.

00:33:05

00:33:06 Mountain ranges

like the Himalayas have arisen.

00:33:09

00:33:09 They're so tall,

they disrupt weather patterns

00:33:12

00:33:13 setting the stage for a colder planet.

00:33:16

00:33:20 The lsthmus of Panama emerges

to connect North and South America,

00:33:25

00:33:25 cleaving the connection between

the Atlantic and the Pacific,

00:33:29

00:33:29 disrupting ocean currents

00:33:30

00:33:30 and tipping the world

even more towards an ice age.

00:33:34

00:33:37 With the planet getting colder,

00:33:39

00:33:39 our primate ancestors

hang on in the tropics,

00:33:42

00:33:42 but a new creature is coming in

that threatens to destroy them.


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00:33:47

00:33:56 Seven million years ago,

00:33:58

00:34:00 our primate ancestors

live safely in the trees.

00:34:03

00:34:04 But their neighborhood

is about to be invaded.

00:34:07

00:34:08 This newcomer will have

as profound an effect on human history

00:34:11

00:34:11 as any other living thing on Earth.

00:34:14

00:34:16 lt seems almost impossible to believe,

00:34:19

00:34:19 but one of the most important things

that will lead to the emergence of us,

00:34:23

00:34:24 is the emergence of grass.

00:34:27

00:34:29 The grasslands appear almost

simultaneously around the world.

00:34:33

00:34:35 We get the African savannas,

00:34:37

00:34:39 we get the Eurasian steppe lands,

00:34:41

00:34:42 we get the North American prairies,

00:34:45


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00:34:46 we get the great grasslands

ofArgentina,

00:34:49

00:34:50 appearing simultaneously

around the world.

00:34:53

00:34:56 ln Eastern Africa, grasslands invade

the traditional woodland habitat

00:35:00

00:35:01 of our ape ancestors.

00:35:02

00:35:03 With fewer trees

and greater gaps between them,

00:35:06

00:35:06 our ancestors have to adapt.

00:35:09

00:35:09 Apes would notice that there's more

and more apes in the same tree

00:35:12

00:35:12 and less and less food,

00:35:14

00:35:15 increasing incentives for apes

00:35:16

00:35:16 to go from one patch of food

to a different one,

00:35:18

00:35:18 separated by grasslands.

00:35:19

00:35:20 Now, one way to do it

is to run like hell, you know.


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00:35:23

00:35:23 The other way to do it is to extend

one's food sources into the grasslands

00:35:27

00:35:27 to seek out the foods

that are available there.

00:35:30

00:35:32 And so, some apes make the move down

into this stark, new habitat.

00:35:37

00:35:40 lt's a landscape better suited

to primates that can walk on two legs.

00:35:45

00:35:46 Keeping their heads up above the tall

grasses to watch for predators.

00:35:51

00:35:54 Standing on two feet

is a revolutionary advance.

00:35:57

00:35:59 Because it frees up our hands.

00:36:01

00:36:03 Hands we will need

to shape human history.

00:36:06

00:36:16 2.6 million years ago,

00:36:18

00:36:21 early proto-humans or hominids

00:36:24

00:36:24 walk an Earth whose rocks are

loaded with the element silicon.


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00:36:28

00:36:31 Created in the cores of stars

billions of years before,

00:36:36

00:36:36 silicon is the second-most

abundant element in Earth's crust.

00:36:40

00:36:40 One of its chemical quirks

is the ability to bond with oxygen

00:36:44

00:36:44 to form crystals

that combine into solid rocks,

00:36:48

00:36:49 rocks that can be chipped

and shaped without shattering.

00:36:52

00:36:54 Hominids started doing this

2.6 million years ago,

00:36:57

00:36:58 breaking cryptocrystalline silicates

to make sharp edges,

00:37:01

00:37:01 and people use them for millions,

literally 2.6 million years.

00:37:05

00:37:10 Simply having a modified stone

with a sharp edge on it,

00:37:13

00:37:13 now suddenly you have a hammer.

00:37:15


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00:37:15 You have a crude cutting edge.

00:37:18

00:37:18 A simple modified stone means

a human can suddenly do

00:37:22

00:37:22 a thousand more things

than we could do previously.

00:37:26

00:37:31 That little extra bit of technology

00:37:34

00:37:34 enabled our ancestors to persist

and eventually turn into us.

00:37:40

00:37:43 Silicon launches the first

technological revolution,

00:37:46

00:37:47 the Stone Age.

00:37:49

00:37:51 Millions of years after it powers

our first handheld devices,

00:37:56

00:37:56 another chemical quirk

of silicon will make it

00:37:59

00:37:59 the height of technology once again.

00:38:01

00:38:04 The next leap towards

becoming truly human

00:38:07

00:38:07 relies on a little-known secret


43/70

of our home planet.

00:38:10

00:38:10 ln the known universe,

00:38:12

00:38:12 it turns out Earth

may have a rare and special power.

00:38:15

00:38:21 Of all the planets and moons

in the solar system,

00:38:24

00:38:24 we think that Earth is unique

in the ability to sustain fire.

00:38:29

00:38:32 Other planets and moons

have lightning and lava.

00:38:35

00:38:38 But only on Earth do we have

the two critical things

00:38:40

00:38:41 we need for fire to burn,

00:38:43

00:38:45 a vast fuel supply

in the form of plants and trees,

00:38:48

00:38:49 and an atmosphere full of oxygen

to fan the flames.

00:38:52

00:38:53 lf fire wasn't a possibility, you'd

have nothing like us running around.

00:38:57


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00:39:01 Homo sapiens,

they made a world with fire.

00:39:04

00:39:10 Our ancestors have fire firmly

under control by 800,000 years ago.

00:39:15

00:39:19 lt's a skill that connects us

back to the very beginning.

00:39:22

00:39:24 Remember that all energy

was created in the Big Bang

00:39:27

00:39:27 and all life is in a competition

for our share of this energy.

00:39:31

00:39:33 Using fire to cook is like having

00:39:35

00:39:35 an external stomach

to break down foods,

00:39:38

00:39:38 releasing more calories,

giving us more energy,

00:39:42

00:39:42 which in turn allows us

to support bigger brains.

00:39:45

00:39:48 Fire is also the ultimate

gateway technology.

00:39:51

00:39:52 We will soon use it


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to turn clay into pottery,

00:39:55

00:39:56 metal into weapons,

00:39:58

00:39:59 water into steam power.

00:40:01

00:40:03 lf you don't have fire, you can't have

the internal combustion engine.

00:40:06

00:40:06 No fire, no metal.

00:40:08

00:40:08 No fire, no rubber.

00:40:09

00:40:11 lt's a technology that opens a world

of possibilities

00:40:14

00:40:14 for creatures that know how to use it.

00:40:16

00:40:22 200,000 years ago,

00:40:24

00:40:27 the modern human

has fully taken shape.

00:40:29

00:40:31 The larynx or voice box

00:40:33

00:40:33 which is high up in the throat

in our ancestors, descends.

00:40:37

00:40:38 More complex sounds are now possible.

00:40:41


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00:40:44 We begin to speak.

00:40:47

00:40:49 For the first time,

information can be shared

00:40:52

00:40:52 between individuals

and across generations.

00:40:56

00:40:57 Humans have gained

a critical advantage

00:40:59

00:40:59 over every other creature on Earth.

00:41:01

00:41:02 You can tell, "My grandfather said

that when the elephants didn't show up

00:41:05

00:41:05 "we go off and hunted zebras."

00:41:06

00:41:07 You know, "My aunt told me that her

cousin found this water hole

00:41:10

00:41:10 "on the other side of that river."

00:41:11

00:41:13 And we can all benefit

00:41:14

00:41:14 and we can all understand what they

mean when they were describing

00:41:17

00:41:17 what they found out on that landscape.

00:41:19


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00:41:20 Language changes humans

from being like stand-alone computers

00:41:24

00:41:24 to being networked computers

where you can share information.

00:41:27

00:41:30 Now, one doesn't need to depend

on one's own personal experience.

00:41:32

00:41:33 One can borrow the personal experience

of anyone

00:41:36

00:41:36 with whom one can communicate.

00:41:37

00:41:38 That's a powerful advantage.

00:41:39

00:41:39 No other creature has that.

00:41:41

00:41:42 As a species,

humans become exponentially smarter.

00:41:46

00:41:47 The global game board has been set,

and we are now ready to play.

00:41:51

00:41:54 1 00,000 years ago, man can move.

00:41:58

00:41:59 We have agile hands

and primitive tools.

00:42:02

00:42:02 We can communicate and control fire.


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00:42:05

00:42:06 We are finally ready to expand

out of our African home

00:42:09

00:42:11 on a path

millions of years in the making.

00:42:14

00:42:19 Shifting continents have linked Africa

and Eurasia

00:42:22

00:42:22 into the largest contiguous landmass

on Earth, Afro-Eurasia.

00:42:27

00:42:29 33 million square miles,

00:42:31

00:42:31 more than twice the surface area

of our entire moon.

00:42:34

00:42:36 For early humans,

00:42:37

00:42:37 this means more than half the land

on Earth can be reached on foot.

00:42:42

00:42:47 Human dispersal

was a crucial game changer.

00:42:50

00:42:51 We are one of the few primates

00:42:53

00:42:53 that live on more than

one continent simultaneously.


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00:42:56

00:42:57 So what that means is that

we're better insulated

00:43:00

00:43:00 from the kinds of things that caused

big mammals to become extinct

00:43:02

00:43:03 than other primates are.

00:43:04

00:43:05 lt's extinction insurance.

Dispersal is extinction insurance.

00:43:08

00:43:12 But just as the world

begins to open itself up to man,

00:43:16

00:43:16 the planet turns on us.

00:43:18

00:43:20 An ice age begins.

00:43:22

00:43:24 Now the planet will test us

like never before.

00:43:27

00:43:29 By 50,000 years ago, glaciers begin

to advance down from the North Pole.

00:43:34

00:43:34 At the same time, humans continue

their conquest of the globe,

00:43:38

00:43:38 arriving in China and Australia.

00:43:40


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00:43:41 By 30,000 years ago, Homo sapiens

reach Europe for the first time.

00:43:45

00:43:46 By 20,000 years ago, with the ice

nearing its most extreme,

00:43:50

00:43:51 the march of man reaches the frigid

tundra of Northeast Siberia.

00:43:55

00:43:57 Despite the trials of the lce Age,

00:43:59

00:44:00 man endures and develops the last

skills we will need to be truly human.

00:44:07

00:44:12 The clues lie in these symbols.

00:44:14

00:44:16 We have taken an intellectual leap,

00:44:18

00:44:18 to think beyond the here and now,

00:44:21

00:44:21 beyond what is simply

needed to survive.

00:44:24

00:44:25 We can only start saying we have

an organism that is human,

00:44:28

00:44:28 that is the same as us,

00:44:29

00:44:29 when we start seeing evidence

of symbolic thought.


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00:44:31

00:44:33 lt's when we start seeing

a picture of a cow

00:44:37

00:44:38 that everybody will recognize

as the picture of a cow.

00:44:41

00:44:41 Because only when we start seeing

all of those things

00:44:44

00:44:44 can we say that is a human.

00:44:46

00:44:47 People or creatures

that think like us,

00:44:50

00:44:51 that see the world

in the same way as us.

00:44:53

00:44:54 And from that moment on,

00:44:55

00:44:55 human history was marked to be

radically different

00:44:56

00:44:58 to any other species on this planet.

00:45:00

00:45:01 Now, with huge amounts of the planet's

water locked up in ice,

00:45:05

00:45:05 sea levels plummet by 300 to 400 feet.

00:45:09


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00:45:10 The last great barrier

to the spread of man is erased.

00:45:14

00:45:14 We come across the Bering Land Bridge

from Siberia to North America.

00:45:19

00:45:23 We are telling the history

of the world in two hours,

00:45:26

00:45:26 and in just one hour, more than

1 3 billion years have already passed.

00:45:31

00:45:31 These years of preparation

have allowed man

00:45:34

00:45:34 to finally emerge

and spread out across the planet.

00:45:37

00:45:38 And human history as we know it

can truly begin.

00:45:41

00:45:48 Our history of the world began with

the beginning of time, the Big Bang.

00:45:53

00:45:54 lt has taken us on a journey

of nearly 14 billion years.

00:45:58

00:46:01 Now, as humans take center stage,

00:46:04

00:46:04 it's important to remember


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00:46:06

00:46:07 just how small a slice of history

we actually occupy.

00:46:11

00:46:12 To make things simple,

00:46:13

00:46:13 imagine compressing 14 billion years

of history

00:46:17

00:46:18 down to just 14 years.

00:46:20

00:46:22 On this scale, the Earth would have

existed only for the past five years.

00:46:28

00:46:29 So that's about a third

of the history of the universe.

00:46:31

00:46:32 Large complex creatures

would have developed seven months ago.

00:46:36

00:46:37 On this scale, dinosaurs went extinct

only about three weeks ago.

00:46:42

00:46:43 The entire recorded history of humans

00:46:45

00:46:46 would span

only the last three minutes.

00:46:49

00:46:50 Modern industrial societies,

00:46:51


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00:46:52 the lndustrial Revolution,

effectively, six seconds ago.

00:46:55

00:46:57 What this shows me is that we humans

have been around

00:47:00

00:47:00 for only a very brief instant in

the recorded history of the universe.

00:47:05

00:47:06 Mankind has waited billions of years

for our brief instant to shine,

00:47:11

00:47:12 as the stars and our evolving planet

00:47:14

00:47:14 carried out the slow work

of organizing the elements

00:47:17

00:47:18 in a way that would

make human history possible.

00:47:20

00:47:27 lt's 1 0,000 B.C.,

00:47:29

00:47:29 less than 1 00,000 years

after expanding out ofAfrica,

00:47:34

00:47:34 man has reached South America.

00:47:36

00:47:37 Humans have met the adversity

of the ice age head on,

00:47:40


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00:47:41 and rather than die off,

00:47:42

00:47:43 we have adapted,

become even more intelligent.

00:47:46

00:47:47 And now

we have colonized the entire globe.

00:47:50

00:47:52 From coast to mountaintop,

00:47:55

00:47:58 from tundra to desert,

00:48:03

00:48:04 humans are there.

00:48:06

00:48:07 Our closest living ancestors,

the chimpanzees, live in the tropics.

00:48:11

00:48:11 They only live in the tropics.

00:48:13

00:48:13 Humans have managed to colonize

the entire globe.

00:48:16

00:48:18 lce age land bridges allowed man

to spread around the world,

00:48:22

00:48:22 but now the ice begins to melt

and sea levels rise again.

00:48:28

00:48:28 Humans are trapped and separated in

two vast and unconnected hemispheres.


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00:48:33

00:48:33 Each pocket of humanity left to make

the best of what it has been given.

00:48:38

00:48:39 As the glaciers recede,

00:48:41

00:48:41 they carve out lakes,

rivers, and bays.

00:48:45

00:48:46 The map as we know it emerges.

00:48:48

00:48:51 ln Africa,

00:48:52

00:48:52 increased rainfall causes Lake

Victoria and Lake Albert to overflow

00:48:56

00:48:58 and form Egypt's Nile River.

00:49:00

00:49:02 ln Eurasia, other rivers emerge,

00:49:04

00:49:05 the Tigris and Euphrates

in Mesopotamia, modern-day lraq.

00:49:09

00:49:11 The lndus in modern-day Pakistan

and China's Yellow and Yangtze.

00:49:16

00:49:18 These river valleys

become critically important

00:49:20

00:49:20 for how human history will now be


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played out

00:49:23

00:49:23 following the retreat

of these ice sheets.

00:49:25

00:49:27 These are the river valleys

whose waters and fertile soils

00:49:31

00:49:31 will allow the first seeds

of civilization to be planted.

00:49:35

00:49:38 With temperatures warming

after the ice age,

00:49:41

00:49:41 plants and animals are more plentiful,

00:49:44

00:49:45 and man can finally

choose to stop moving.

00:49:48

00:49:50 Permanent settlements begin.

00:49:52

00:49:54 Populations grow.

00:49:55

00:50:00 With more mouths to feed,

our ancestors have to get clever.

00:50:04

00:50:06 They had to find a way

to increase the amount of food

00:50:08

00:50:08 they could get from the surroundings.


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00:50:10

00:50:11 Now, one discovery forever changes

the planet and the path of mankind.

00:50:17

00:50:20 We learn to plant seeds.

00:50:22

00:50:25 And the seeds we sow

come from the same plants

00:50:28

00:50:28 that millions of years earlier

spurred our evolution from ape to man,

00:50:33

00:50:33 the unheralded hero

of human history, grass.

00:50:38

00:50:40 A grass seed is tiny, right?

lt's no food.

00:50:42

00:50:42 l can hunt a bison

or l can take grass.

00:50:44

00:50:45 You hunt a bison, right?

00:50:47

00:50:47 lronically, grass seeds

become the most important food crops

00:50:50

00:50:50 in the world, but they're the things

that are ignored by hunter-gatherers

00:50:53

00:50:53 for thousands and thousands of years.


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00:50:55

00:50:55 People don't start using them until

they absolutely have to use them.

00:50:58

00:51:00 Some of the species of grass

that we are most familiar with

00:51:03

00:51:03 includes sugarcane.

00:51:05

00:51:05 lt includes wheat and rye and barley,

00:51:09

00:51:09 all of the cereal crops

are types of grass.

00:51:12

00:51:13 So it's not just

that beautiful green lawn

00:51:16

00:51:16 that we measure

our middle class success from.

00:51:18

00:51:19 lt's also the staple crop

upon which civilization depends.

00:51:24

00:51:24 lt is the majority

of our calorie intake.

00:51:27

00:51:29 Once again,

it all goes back to the Big Bang.

00:51:32

00:51:34 Central to the story of all life


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is our competition for that energy

00:51:37

00:51:37 created at the beginning of time.

00:51:39

00:51:40 Just as oxygen gave us an edge,

00:51:43

00:51:43 just as fire allowed us

to consume more calories,

00:51:47

00:51:47 switching to farming

is an energy revolution.

00:51:50

00:51:51 A hunter-gatherer

needs 1 0 square miles of territory

00:51:54

00:51:54 to provide himself

with enough sustenance,

00:51:57

00:51:57 enough energy in the form of

plants and meat to survive.

00:52:01

00:52:02 A farmer can harvest the sun's energy

so efficiently,

00:52:06

00:52:06 he can fulfill his needs using

only a tenth of a square mile of land.

00:52:11

00:52:14 ln the warming after the last ice age,

farming begins to take hold

00:52:18


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of the world.

00:52:55

00:52:56 Unlike the Fertile Crescent

and the rest ofAfro-Eurasia,

00:53:00

00:53:00 places like sub-Saharan Africa

and the Americas

00:53:03

00:53:03 have very few wild species

that can be easily domesticated.

00:53:08

00:53:10 lt's a critical difference.

00:53:13

00:53:13 People blessed with the right mix

of plants and animals

00:53:16

00:53:16 will become more powerful

00:53:18

00:53:18 and get a massive head start

on the road to the modern world.

00:53:22

00:53:30 One animal that gives any human

who can tame it

00:53:33

00:53:33 an almost unbeatable edge

is the horse.

00:53:37

00:53:39 lt's a little-known fact that although

horses first evolved in the Americas,

00:53:43


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00:53:43 they died out there

along with many other large mammals

00:53:47

00:53:47 around 1 0,000 B.C.

00:53:49

00:53:49 There were at least three species

of ice age horses in North America,

00:53:52

00:53:52 maybe more, some as small as ponies,

some as big as Clydesdales.

00:53:56

00:53:56 And they had evolved in North America

for 40 million years.

00:53:59

00:53:59 They're part of the whole history, and

then... They're gone. They're gone.

00:54:03

00:54:04 These powerful potential allies

00:54:06

00:54:06 disappear before they can be used

by the first North Americans.

00:54:10

00:54:10 Fortunately before that happened,

00:54:12

00:54:12 large numbers of horses escaped back

across the Bering Strait land bridge

00:54:16

00:54:16 and spread out

across the great grasslands

00:54:18


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00:54:18 and steppe lands of Central Eurasia.

00:54:20

00:54:22 A narrow escape that had

a profound effect on human history.

00:54:26

00:54:27 Around 4,000 B.C.,

00:54:29

00:54:29 nomadic people in Central Asia

learn to tame them for the first time.

00:54:34

00:54:36 Domesticated horses will be harnessed

across Eurasia,

00:54:40

00:54:40 advancing everything

from work to warfare.

00:54:43

00:54:47 Perhaps no other animal

has had a bigger influence

00:54:50

00:54:50 on the course of human history.

00:54:52

00:54:54 And the circle wouldn't be complete

for another 5,000 years

00:54:58

00:54:58 when Christopher Columbus

would bring horses with him

00:55:01

00:55:01 on his second voyage to the Americas.

00:55:04

00:55:05 His horses would be the first


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to set hooves in the Americas

00:55:09

00:55:09 since the great die-off

over 1 0,000 years earlier.

00:55:13

00:55:21 6,000 years ago,

domestication of animals and plants

00:55:25

00:55:25 sets the stage for the next phase

of human history.

00:55:29

00:55:30 Like clouds of interstellar dust

gathering in material to form stars,

00:55:35

00:55:35 a type of gravity is at work

as places like Sumeria,

00:55:39

00:55:39 located in part of the

Fertile Crescent known as Mesopotamia,

00:55:43

00:55:43 draw in people,

support large populations,

00:55:46

00:55:46 and spin up into centers of power

and innovation.

00:55:50

00:55:52 By 3,000 B.C.,

00:55:54

00:55:54 some of these Sumerian settlements

can truly be called our first cities.


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00:56:46 ln the case of the Middle East,

wheat and barley.

00:56:48

00:56:49 ln the case of wheat and barley,

00:56:50

00:56:50 they both ripen

at about the same time.

00:56:53

00:56:53 Humans have to gather the seeds

at the same time.

00:56:56

00:56:56 So now we have our food for the year

that has arrived in one hit.

00:57:00

00:57:01 lt's like getting your salary

paid once a year.

00:57:04

00:57:04 You need to record it.

You need to plan,

00:57:06

00:57:06 because if inevitably your crop fails,

you have famine.

00:57:10

00:57:11 And you're not gonna have another go

for another 1 2 months.

00:57:14

00:57:19 ln these first cities, crops are king.

00:57:23

00:57:25 To keep track of them,

00:57:27


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00:57:27 our ancestors

develop the first writing.

00:57:30

00:57:30 To protect them, the first armies.

00:57:33

00:57:34 And to administer them,

the beginnings of politics.

00:57:37

00:57:38 When you have hundreds or thousands

of people who are living together,

00:57:42

00:57:42 there's simply too many people

00:57:43

00:57:43 to sort of run around

and create a census.

00:57:45

00:57:45 lt creates a need for government.

00:57:48

00:57:49 lt creates a need for some form of

social and political hierarchy.

00:57:53

00:57:55 Planting seeds has set man

on a new path.

00:57:57

00:57:59 Settlements have grown into cities.

00:58:01

00:58:02 But to take the next epic step

from city to civilization,

00:58:07

00:58:07 we'll need the help


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of a very surprising creature.

00:58:11

00:58:22 5,000 years ago,

00:58:25

00:58:25 after wandering the Earth

for more than 1 00,000 years,

00:58:29

00:58:30 mankind has begun to settle down.

00:58:32

00:58:35 We cluster near rivers,

along the Tigris and Euphrates,

00:58:39

00:58:41 the Nile, the lndus,

00:58:45

00:58:47 the Yellow and Yangtze.

00:58:49

00:58:49 Civilizations are about to take off.

00:58:51

00:58:54 But first,

they must all master one thing, trade.

00:58:58

00:58:59 The more they exchange goods

and learn from other lands,

00:59:02

00:59:02 the faster they grow.

00:59:04

00:59:05 lt seems that long-distance trade

and communication

00:59:08

00:59:08


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00:59:10

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