WEBVTT

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<v Speaker 1>We are the most complex creature on this planet, a

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<v Speaker 1>big brain, two legged mammal. We've risen from the raw

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<v Speaker 1>materials of the Earth to dominate and shape it.

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<v Speaker 2>Wind the clock backwards, and.

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<v Speaker 1>The story of how we got to be us is

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<v Speaker 1>a puzzle that defies all logic. Through nearly four billion

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<v Speaker 1>years of evolutionary twists and turns, disasters, stripe predators threatened

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<v Speaker 1>to wipe us out. From rodent to reptile, we face

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<v Speaker 1>extinction at every turn, from the land into the water,

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<v Speaker 1>fighting to survive every step of the way, from fish

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<v Speaker 1>to worm, back to the.

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<v Speaker 2>Very first spark.

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<v Speaker 1>Of life, to a single simple self. And this is

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<v Speaker 1>the most extraordinary, improbable story ever told, the story of

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<v Speaker 1>mankind rising four billion years ago. A ball of rock

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<v Speaker 1>and dust spins in the frozen vacuum of space. This

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<v Speaker 1>isn't Mars.

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<v Speaker 2>Or Venus. This hell is Earth.

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<v Speaker 1>This seething, lifeless mass of molten lava will become home

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<v Speaker 1>to nearly nine million living species. But generating life from

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<v Speaker 1>this will take a chain of events that defies the

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<v Speaker 1>laws of probability.

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<v Speaker 2>There are many theories.

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<v Speaker 1>Nobody knows exactly our where life began, but it couldn't

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<v Speaker 1>happen without water. Experts believe asteroids or commets delivered it. Here,

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<v Speaker 1>the water is churning with chemicals and organic compounds. Lightning

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<v Speaker 1>strikes the chemical soup at the right place and the

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<v Speaker 1>right time. Billions of volts of electricity trigger a chain

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<v Speaker 1>of improbable coincidences. The chemicals atoms join up in a

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<v Speaker 1>precise sequence, creating a bundle of genetic material. These fragile

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<v Speaker 1>genes don't stand a chance in this extreme environment, but

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<v Speaker 1>love strikes again. A blob of oily material engulfs a

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<v Speaker 1>single chain to create the first ever cell. Now, the

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<v Speaker 1>genes send out messages, chemical instructions, and three point five

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<v Speaker 1>billion years ago, they do something extraordinary. They copy themselves

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<v Speaker 1>and the cell to create a perfect clone. This is

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<v Speaker 1>the very first living thing. Every human, every animal, every bug,

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<v Speaker 1>every plant can trace its origins to this single cell.

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<v Speaker 1>The genes tell each cell to reproduce, guaranteeing their survival

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<v Speaker 1>as they pass from one generation to the next. For

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<v Speaker 1>two billion years, the only living things are simple single cells.

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<v Speaker 1>But a random accident changes everything. Two cells merge, their

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<v Speaker 1>genes combine. The merge cell clones itself. Its offspring contains

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<v Speaker 1>genes from not one, but two cells, two parents. We

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<v Speaker 1>call this accident sex. Sex introduces variation. Occasionally things go

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<v Speaker 1>wrong as the cells reproduce, genes get deleted, duplicated. These

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<v Speaker 1>cells are mutants. Mutations pile up, differences increase until the

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<v Speaker 1>cells become so different their separate species. The tree of

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<v Speaker 1>life branches out into billions of species, but only one

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<v Speaker 1>will lead to us. Mutating and diversifying, spreading out through

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<v Speaker 1>the oceans, getting bigger, more complex, until our ancestor is

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<v Speaker 1>a three inch long water worm. This is US five

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<v Speaker 1>hundred and fifty million years ago. Mutations create distinct male

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<v Speaker 1>and female sexes. We produce more offspring, passing on more

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<v Speaker 1>genes Mars and venus. Boy meets girl.

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<v Speaker 2>It all starts.

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<v Speaker 1>Here, but finding a partner is almost impossible When every

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<v Speaker 1>living thing is blind in this sea of darkness. The

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<v Speaker 1>ability to see will give us a critical advantage. Nature's

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<v Speaker 1>most perfect innovation begins to take shape. A handful of

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<v Speaker 1>skin cells mutate. Now we can tell dark from light,

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<v Speaker 1>find more prey, dodge more predators. We live longer and

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<v Speaker 1>produce more offspring. Soon, creatures with light sensitive cells dominate

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<v Speaker 1>the population over countless generations. More mutations refine the cells.

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<v Speaker 1>This is natural selection in action, the process that allows

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<v Speaker 1>every living thing to adapt to the world, and that

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<v Speaker 1>gives our ancestor eyes. We can see, and everything we

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<v Speaker 1>can see is descended from that first single cell. But

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<v Speaker 1>we need to make sense of what we're seeing behind

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<v Speaker 1>our eyes A tiny collection of nerve cells clustered together.

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<v Speaker 1>They're no bigger than a pinhead. One day this will

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<v Speaker 1>be nature's most complex and mysterious organ. Five hundred and

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<v Speaker 1>twenty one million years ago, this is the very first brain.

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<v Speaker 1>We are a fish like creature called Milo Conmingia. Our

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<v Speaker 1>brain can make simple decisions, process basic information, but we

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<v Speaker 1>can't outwith or outrun this anoma Lacarus, the great white

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<v Speaker 1>of the ancient oceans. O odds of extinction are far

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<v Speaker 1>higher than survival. Of all the species that have ever lived,

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<v Speaker 1>ninety nine percent of them are extinct, But a lucky

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<v Speaker 1>roll of the genetic dice helps Milo. Tough enough, your jaws,

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<v Speaker 1>your teeth. They exist because over four hundred million years ago,

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<v Speaker 1>we face the wrath of a primeval monster. Jaws and

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<v Speaker 1>teeth mean more food and a bigger, stronger body. Until

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<v Speaker 1>three hundred and seventy five million years ago, we're a

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<v Speaker 1>foot long armored fish.

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<v Speaker 2>We look invincible, but we're not. Now.

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<v Speaker 1>The choice is simple, get out his way or die.

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<v Speaker 1>We're safe in the shallow water, or are we. The

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<v Speaker 1>water's stagnant, there's not enough oxygen. Starved of oxygen, cells

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<v Speaker 1>shut down, Toxic carbon dioxide saturates the blood. We can't

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<v Speaker 1>go back, we can't stay here. There's only one place

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<v Speaker 1>left for.

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<v Speaker 2>Us to go.

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<v Speaker 1>It takes over three billion years for our ancestor to

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<v Speaker 1>evolve from a single cell to a foot long armored fish.

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<v Speaker 1>Now our future looks bleak, but natural selection throws us

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<v Speaker 1>a lifeline. Over millions of years, thousands of generations, our

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<v Speaker 1>body adapts until we do something no fish has done before.

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<v Speaker 2>Breathe.

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<v Speaker 1>There the air travels into a new organ, a lung.

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<v Speaker 1>Take a breath, and remember it's because a monster fish

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<v Speaker 1>chased our ancestor into the stagnant water, forcing them to

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<v Speaker 1>breathe air. We're in ichthyostega. We can breathe air or water,

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<v Speaker 1>closing off our windpipe to switch between lungs and gills. Today,

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<v Speaker 1>our gills are gone, but the mechanism remains, and sometimes

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<v Speaker 1>times at spasms, giving us the hiccups three hundred and

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<v Speaker 1>sixty five million years ago. We stick our head out

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<v Speaker 1>of the water.

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<v Speaker 2>There's a swamp.

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<v Speaker 1>Behind us, paradise ahead. The choice is simple, but the

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<v Speaker 1>consequences are immense. We pull ourselves out of the water

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<v Speaker 1>and change the course of history. This is the moment

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<v Speaker 1>we leave the water for a new life on land.

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<v Speaker 1>But all this food comes at a price. The fierce

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<v Speaker 1>sun dries out our skin, the hard terrain tears at

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<v Speaker 1>our soft feet. Ichthyostega is a fish out of water.

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<v Speaker 1>We dodged extinction in a stagnant swamp, only to slam

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<v Speaker 1>straight into another deadly environment. Countless creatures perish, but natural

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<v Speaker 1>selection helps our ancestor adapt. Thicker skin protects us from

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<v Speaker 1>the sun, and tough claws that will one day become

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<v Speaker 1>our fingernails help us move across the rough terrain until

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<v Speaker 1>we're cassanaria. We've adapted to life on life, but our

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<v Speaker 1>eggs haven't. They need a tough shell to stop them

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<v Speaker 1>drying out in the sun. The problem is males can't

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<v Speaker 1>fertilize an egg through a tough shell, but they can

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<v Speaker 1>fertilize it before the shell forms inside the female's body.

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<v Speaker 1>Sex as we know it starts here. The result is

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<v Speaker 1>a masterpiece of evolution, an egg in a tough shell

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<v Speaker 1>with all the nutrients the embryo needs sealed inside. Sex

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<v Speaker 1>is the best way to increase genetic variety and keep

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<v Speaker 1>our species alive. Thanks to sex, three hundred and forty

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<v Speaker 1>million years ago, Casinaria becomes the first of our ancestors

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<v Speaker 1>to live entirely on land. It's a new world, different

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<v Speaker 1>from anything we've experienced up to now. We breathe air,

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<v Speaker 1>support our own weight, and wrestle with an onslaught of

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<v Speaker 1>new smells, sounds, sights, bombarded with information, our brains evolve.

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<v Speaker 1>We're smart, and we need to be. From that first

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<v Speaker 1>creature to set foot on land, millions of species have evolved.

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<v Speaker 1>More competitors mean less food to go round. A mutation

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<v Speaker 1>gives us bigger, more powerful jaw muscles. It's a critical advantage.

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<v Speaker 1>We can eat more food faster, and it shows we're Varnops,

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<v Speaker 1>a slab of pure meat eating power. This little creature

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<v Speaker 1>is a proterosaurus wants a competitor. Now he's prey with

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<v Speaker 1>Varyonops for an ancestor. Our success seems certain, but our

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<v Speaker 1>story is a rollercoaster ride, and there's a big dip coming.

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<v Speaker 2>Two hundred and fifty.

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<v Speaker 1>Million years ago, thousands of miles away in Siberia, the

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<v Speaker 1>Earth tears itself apart. A giant plume of magma surges

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<v Speaker 1>up from deep inside the planet. Molten rock oozes through

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<v Speaker 1>cracks in the Earth's crust, covering an area the size

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<v Speaker 1>of the United States under a layer one thousand feet deep,

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<v Speaker 1>and it continues for half a million years. Trillions of

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<v Speaker 1>tons of noxious carbon dioxide trapped the Sun's heat inside

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<v Speaker 1>the atmosphere, Temperatures soar to over one hundred degrees. Plants,

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<v Speaker 1>the plant eaters, and eventually the meat eaters perish. Ninety

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<v Speaker 1>five percent of all species die, only a tiny handful

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<v Speaker 1>hang off among them, us and another species that will

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<v Speaker 1>one day become the dinosaurs. As the fight for survival

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<v Speaker 1>winds down, the battle for supremacy begins. Thirty million years

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<v Speaker 1>since volcanic eruptions wiped out ninety five percent of all

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<v Speaker 1>living things. When the eruptions struck, we look like a

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<v Speaker 1>large lizard. Now we're a catsized creature covered in fur

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<v Speaker 1>called ectininion. Imagine you've survived the apocalypse, and today is

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<v Speaker 1>the day it's finally safe to venture out of hiding,

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<v Speaker 1>you discover.

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<v Speaker 2>You're not alone.

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<v Speaker 1>The last thing you want to see is a dinosaur,

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<v Speaker 1>a five foot tall Herrerasaurus. She evolved from one of

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<v Speaker 1>the small reptiles that survived the mass extinction. Her ancestors

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<v Speaker 1>adapted faster than ours, putting the dinosaurs ahead in the

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<v Speaker 1>game and leaving us playing ketchup. This one's fast, strong,

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<v Speaker 1>and hungry. We're staring down the barrel of an evolutionary gun.

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<v Speaker 1>Our only hope natural selection. Over millions of years, we

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<v Speaker 1>get smaller.

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<v Speaker 2>So we're harder to catch.

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<v Speaker 1>We become nocturnal, making us harder to see.

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<v Speaker 2>We're cold and scared.

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<v Speaker 1>Tiny muscles around the base of each hair contract making

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<v Speaker 1>our fur stand on end, trapping air as insulation. That's

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<v Speaker 1>why today, when we're cold or startled, we get goosebumps.

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<v Speaker 1>Our senses sharpened so we can see here and smell

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<v Speaker 1>a dinosaur before a dinosaur sees us. Inside our brain,

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<v Speaker 1>a new structure evolves, the neocortex, the home of complex

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<v Speaker 1>thought that allows us to analyze the situation and respond.

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<v Speaker 1>It will one day give us the power to imagine, create,

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<v Speaker 1>and communicate. Sixty six million years ago. We're Batadom, a

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<v Speaker 1>two inch long, shrewd like creature living on our wits

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<v Speaker 1>in the ancient forests of Montana. Humanity's future depends on

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<v Speaker 1>Badadan's sharp senses and supercharged brains. If these fail, we

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<v Speaker 1>may never exist. The dinosaurs may be the best thing

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<v Speaker 1>that ever happened to us. Thanks to them, we have

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<v Speaker 1>powerful senses and brilliant brains. Without them, we could still

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<v Speaker 1>be laying eggs to protect our offspring from hungry dinosaurs.

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<v Speaker 1>We evolved to give birth to live young. Instead of

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<v Speaker 1>leaving them to fend for themselves, we nurture them with milk.

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<v Speaker 2>Sweat.

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<v Speaker 1>Glens evolved to become mammary glands. It's a major milestone

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<v Speaker 1>in our journey from cell to human, the birth of

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<v Speaker 1>a new kind of animal, one that will branch out

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<v Speaker 1>into more than four thousand species, from the smallest mouse

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<v Speaker 1>to the largest whale. To us, the mammals have arrived.

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<v Speaker 1>The dinosaurs help shape who we are, but we lost

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<v Speaker 1>the battle for supremacy. The dinosaur's reign for over one

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<v Speaker 1>hundred and sixty five million years. Nothing can stop.

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<v Speaker 3>Them, or so it seems.

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<v Speaker 1>Montana, sixty five million years ago, an asteroid strikes eighteen

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<v Speaker 1>hundred miles away off Mexico's Yucatan Peninsula. A small rat

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<v Speaker 1>like mammal is about to face the fight of his life.

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<v Speaker 1>Lose and humans may never exist. Pulverized rock and dust

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<v Speaker 1>engulfed the entire planet, the only way out is to dig.

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<v Speaker 1>Smoke and ash from the fires block out the sun.

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<v Speaker 1>Temperatures plummet, vegetation dies. The local disaster becomes a global catastrophe.

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<v Speaker 1>For the dinosaurs, it's a disaster. They're big creatures with

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<v Speaker 1>big appetites, and now that's a big problem. As the

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<v Speaker 1>mighty fall, the small rise to the top. Bugs tough

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<v Speaker 1>enough to survive the worst catastrophe, gorge on the dead

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<v Speaker 1>and decaying, and they make the perfect snack. Next time

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<v Speaker 1>you're about to squash a bug, remember that we wouldn't

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<v Speaker 1>be here without them. Sixty four million years ago, our

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<v Speaker 1>bug eating ancestor is purgatorious, just under six inches long.

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<v Speaker 1>This little creature and the rest of his mammal family

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<v Speaker 1>are the unlikely inheritors of the dinosaur's crown. Mammals become

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<v Speaker 1>the dominant animals on land. They spread out across the

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<v Speaker 1>newly formed continents. Our future rests on their tiny shoulders

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<v Speaker 1>from the ashes of destruction. New life begins to sprout.

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<v Speaker 1>Sixty million years ago, fruit ripens on the trees, packed

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<v Speaker 1>full of nutrients. The more fruit we eat, the longer

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<v Speaker 1>we live. We leave solid ground for a new life

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<v Speaker 1>in the trees. A new world demands a new body.

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<v Speaker 1>We've come a long way from that first single cell. Now,

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<v Speaker 1>at last, we're beginning to glimpse of family resemblance. We're

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<v Speaker 1>alti at Lassius, one of the first members of a

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<v Speaker 1>new group of mammals, the primates.

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<v Speaker 2>By fifty six million years.

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<v Speaker 1>Ago, we've adapted to our world, but that world is

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<v Speaker 1>about to change again. Over ten million years, extreme temperature

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<v Speaker 1>shifts ravage the forests. Forests gets smaller, food gets harder

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<v Speaker 1>to reach. Natural selection intervenes again. Our tail shrinks back

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<v Speaker 1>to the base of the spine, where it stays as

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<v Speaker 1>the coccix, a reminder of our days spent leaping through

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<v Speaker 1>the trees. Instead of leaping, we stretch, our arms grow

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<v Speaker 1>long and flexible. Changing temperatures changed our ancestors and us forever,

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<v Speaker 1>but the planets not finished yet. Deep underground, the African

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<v Speaker 1>and Arabian plates pull apart the land between them drops

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<v Speaker 1>to form the East African Rift Valley. Along its edge,

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<v Speaker 1>a three and a half thousand mile long mountain shape

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<v Speaker 1>rises up rains from the Indian Ocean, once watered all

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<v Speaker 1>of Africa. Now the mountains block their path, The trees

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<v Speaker 1>get even further apart, the food harder to reach. We're starving, desperate.

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<v Speaker 1>Four point four million years ago. The will to survive

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<v Speaker 1>that's driven us from a single cell in the ocean

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<v Speaker 1>to a complex primate in the forests of Africa is

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<v Speaker 1>about to make us do something extraordinary, something no primate

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<v Speaker 1>has ever done before. After three billion years of evolution,

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<v Speaker 1>we hit an evolutionary dead end. We are Artipithecus ramidus,

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<v Speaker 1>four feet tall at eighty pounds, with a brain the

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<v Speaker 1>size of an orange. Our dense rainforest home has become

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<v Speaker 1>patchy forest. We can stand on branches move along them,

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<v Speaker 1>but to reach more food, we need to let go.

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<v Speaker 1>Four point four million years ago, these are our first

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<v Speaker 1>steps on two legs. Walking takes us to the food

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<v Speaker 1>and leaves our hands free to pick it.

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<v Speaker 2>It catches on fast.

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<v Speaker 1>Artipithecus is smart enough to copy and learn. Walking gets

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<v Speaker 1>past from parent to child. Over the next one point

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<v Speaker 1>two million years Our body evolves so that we can

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<v Speaker 1>walk further and faster. Finding shelter, a mate and food

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<v Speaker 1>gets easier, but childbirth gets harder. With a narrower pelvis,

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<v Speaker 1>giving birth to a fully developed infant becomes impossible. Babies

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<v Speaker 1>have to come out early when their heads are smaller

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<v Speaker 1>and they're barely developed.

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<v Speaker 2>That's why we are.

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<v Speaker 1>One of the few species to spend years caring for

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<v Speaker 1>our offspring, protecting them, feeding them, and keeping them out

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<v Speaker 1>of trouble. Three point two million years ago, we're an

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<v Speaker 1>Australo pitheken. Our brain is the size of a grapefruit,

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<v Speaker 1>and we walk on two legs all the time. We

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<v Speaker 1>got lucky, the lion has already eaten.

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<v Speaker 2>This time.

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<v Speaker 1>We can't outrun our predators. The only way to survive

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<v Speaker 1>is to outthink that the smarter we get, the.

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<v Speaker 2>Longer we live.

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<v Speaker 1>Natural selection promotes the mutations that improve.

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<v Speaker 2>Our brain power. Your jaw muscles released from the.

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<v Speaker 1>Muscle's vice like grip.

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<v Speaker 2>The brain is free to grow.

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<v Speaker 1>It doubles in size two point three million years ago.

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<v Speaker 1>This is Homo habilis, also known as handyman. Walking on

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<v Speaker 1>two legs with a big brain. We're the first of

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<v Speaker 1>an entirely new type of creature. We're the first man.

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<v Speaker 1>We're bigger, stronger, and hungry than ever before. There's food

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<v Speaker 1>out there, but it's more likely to eat us before

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<v Speaker 1>we can eat it. We're a scavenger working alone. We

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<v Speaker 1>eat whatever we can find. The edge is razor sharp.

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<v Speaker 1>We have just made the very first tool. Armed with this,

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<v Speaker 1>we will change.

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<v Speaker 2>The world.

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<v Speaker 1>East Africa two point three million years ago, after over

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<v Speaker 1>three billion years of evolution, we take our fate into

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<v Speaker 1>our own hands. We are the first species to make

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<v Speaker 1>tools in this hostile environment. We need every advantage we

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<v Speaker 1>can get. We must fight off predators, starvation, and our

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<v Speaker 1>own relatives. There's no meat left. It looks like we're

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<v Speaker 1>going hungry again. But there's bone marrow locked inside packed

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<v Speaker 1>within her. The tool is the key to a whole

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<v Speaker 1>new way of life. We'll use it to grow crops,

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<v Speaker 1>build cities, and travel into space. Our thumbs become stronger,

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<v Speaker 1>puld a cup, pick up a pen. We can do

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<v Speaker 1>this because two million years ago, tool use changed our

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<v Speaker 1>bodies and the course of evolution. We've pieced together our

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<v Speaker 1>ancestors story from their bones, but from the vastness of Africa.

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<v Speaker 1>All the bones of our early human ancestors ever found,

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<v Speaker 1>would fit into the back of a pick up. Less

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<v Speaker 1>than one bone in a billion becomes a fossil factor

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<v Speaker 1>in the chances of finding those bones across millions of

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<v Speaker 1>square miles, and it's clear most of what has lived.

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<v Speaker 2>Has been lost.

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<v Speaker 1>Our family tree is a giant puzzle with most of

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<v Speaker 1>the pieces missing. But one point eight million years ago,

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<v Speaker 1>a piece falls into place and we find a new

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<v Speaker 1>species on the scene, Homo erectus. Until this point we

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<v Speaker 1>were scavengers, but now we're hunters, and we've learned how

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<v Speaker 1>to work with other members of our species. The hunt

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<v Speaker 1>is on. The impala can run fast, but we can

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<v Speaker 1>run further. Low shoulders and long torsos stabilize us. Powerful

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<v Speaker 1>buttock muscles contract, expand, and push us forwards. Sweat stops

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<v Speaker 1>us from overheating. Covered in fur, the Impalla is exhausted.

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<v Speaker 1>Fire it sparks an idea that will make our ancestors

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<v Speaker 1>human warmth. Light, safety is within reach. Nature's power is

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<v Speaker 1>in our hands. Protected from the terrors of the dark,

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<v Speaker 1>our extended family gather round By working together, These earliest

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<v Speaker 1>families get food more often, so we live longer. This

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<v Speaker 1>is the advantage of family life, the reason most of

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<v Speaker 1>us live as we do today. Meat is too precious

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<v Speaker 1>to waste, and cooked meat is easier to chew. The

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<v Speaker 1>powerful molars used to chew tough raw food retreat back

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<v Speaker 1>into the gums, where they'll stay as our wisdom teeth.

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<v Speaker 1>Thirty five percent of us never even grow them, a

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<v Speaker 1>sign that they may be evolving out of existence. With

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<v Speaker 1>less energy spent on chewing, our ancestors have energy to spare.

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<v Speaker 1>The brain increases to the size of a softball, fifty

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<v Speaker 1>percent larger than before the invention of cooking. Erectus is

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<v Speaker 1>the cleverest, most cooperative ancestor to date, but with several

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<v Speaker 1>adult males in an extended family, rivalries are inevitable, communicate

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<v Speaker 1>and will live longer. A natural selection kicks in. Our tongue,

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<v Speaker 1>changes shape and moves down our throat, carrying the larynx

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<v Speaker 1>with it, allowing us to form different shapes in our mouths,

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<v Speaker 1>making different sounds and ultimately words. Speech is our greatest tool.

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<v Speaker 1>It's the last piece of the puzzle that turns our

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<v Speaker 1>ancestors into us. Two hundred thousand years ago, after a

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<v Speaker 1>three point three billion year battle for survival. We've arrived.

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<v Speaker 1>We are Homo sapiens, meaning wise men. Pound for pound,

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<v Speaker 1>we have the largest brain of any creature on Earth.

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<v Speaker 2>Armed with tools, speech, and.

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<v Speaker 1>Superior intelligence, we spread out across every continent, evolve and

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<v Speaker 1>adapt to new environments, new challenges, until we become the

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<v Speaker 1>undisputed masters of the world.