Speaker 1: We are the most complex creature on this planet, a
big brain, two legged mammal. We've risen from the raw
materials of the Earth to dominate and shape it.
Speaker 2: Wind the clock backwards, and.
Speaker 1: The story of how we got to be us is
a puzzle that defies all logic. Through nearly four billion
years of evolutionary twists and turns, disasters, stripe predators threatened
to wipe us out. From rodent to reptile, we face
extinction at every turn, from the land into the water,
fighting to survive every step of the way, from fish
to worm, back to the.
Speaker 2: Very first spark.
Speaker 1: Of life, to a single simple self. And this is
the most extraordinary, improbable story ever told, the story of
mankind rising four billion years ago. A ball of rock
and dust spins in the frozen vacuum of space. This
isn't Mars.
Speaker 2: Or Venus. This hell is Earth.
Speaker 1: This seething, lifeless mass of molten lava will become home
to nearly nine million living species. But generating life from
this will take a chain of events that defies the
laws of probability.
Speaker 2: There are many theories.
Speaker 1: Nobody knows exactly our where life began, but it couldn't
happen without water. Experts believe asteroids or commets delivered it. Here,
the water is churning with chemicals and organic compounds. Lightning
strikes the chemical soup at the right place and the
right time. Billions of volts of electricity trigger a chain
of improbable coincidences. The chemicals atoms join up in a
precise sequence, creating a bundle of genetic material. These fragile
genes don't stand a chance in this extreme environment, but
love strikes again. A blob of oily material engulfs a
single chain to create the first ever cell. Now, the
genes send out messages, chemical instructions, and three point five
billion years ago, they do something extraordinary. They copy themselves
and the cell to create a perfect clone. This is
the very first living thing. Every human, every animal, every bug,
every plant can trace its origins to this single cell.
The genes tell each cell to reproduce, guaranteeing their survival
as they pass from one generation to the next. For
two billion years, the only living things are simple single cells.
But a random accident changes everything. Two cells merge, their
genes combine. The merge cell clones itself. Its offspring contains
genes from not one, but two cells, two parents. We
call this accident sex. Sex introduces variation. Occasionally things go
wrong as the cells reproduce, genes get deleted, duplicated. These
cells are mutants. Mutations pile up, differences increase until the
cells become so different their separate species. The tree of
life branches out into billions of species, but only one
will lead to us. Mutating and diversifying, spreading out through
the oceans, getting bigger, more complex, until our ancestor is
a three inch long water worm. This is US five
hundred and fifty million years ago. Mutations create distinct male
and female sexes. We produce more offspring, passing on more
genes Mars and venus. Boy meets girl.
Speaker 2: It all starts.
Speaker 1: Here, but finding a partner is almost impossible When every
living thing is blind in this sea of darkness. The
ability to see will give us a critical advantage. Nature's
most perfect innovation begins to take shape. A handful of
skin cells mutate. Now we can tell dark from light,
find more prey, dodge more predators. We live longer and
produce more offspring. Soon, creatures with light sensitive cells dominate
the population over countless generations. More mutations refine the cells.
This is natural selection in action, the process that allows
every living thing to adapt to the world, and that
gives our ancestor eyes. We can see, and everything we
can see is descended from that first single cell. But
we need to make sense of what we're seeing behind
our eyes A tiny collection of nerve cells clustered together.
They're no bigger than a pinhead. One day this will
be nature's most complex and mysterious organ. Five hundred and
twenty one million years ago, this is the very first brain.
We are a fish like creature called Milo Conmingia. Our
brain can make simple decisions, process basic information, but we
can't outwith or outrun this anoma Lacarus, the great white
of the ancient oceans. O odds of extinction are far
higher than survival. Of all the species that have ever lived,
ninety nine percent of them are extinct, But a lucky
roll of the genetic dice helps Milo. Tough enough, your jaws,
your teeth. They exist because over four hundred million years ago,
we face the wrath of a primeval monster. Jaws and
teeth mean more food and a bigger, stronger body. Until
three hundred and seventy five million years ago, we're a
foot long armored fish.
Speaker 2: We look invincible, but we're not. Now.
Speaker 1: The choice is simple, get out his way or die.
We're safe in the shallow water, or are we. The
water's stagnant, there's not enough oxygen. Starved of oxygen, cells
shut down, Toxic carbon dioxide saturates the blood. We can't
go back, we can't stay here. There's only one place
left for.
Speaker 2: Us to go.
Speaker 1: It takes over three billion years for our ancestor to
evolve from a single cell to a foot long armored fish.
Now our future looks bleak, but natural selection throws us
a lifeline. Over millions of years, thousands of generations, our
body adapts until we do something no fish has done before.
Speaker 2: Breathe.
Speaker 1: There the air travels into a new organ, a lung.
Take a breath, and remember it's because a monster fish
chased our ancestor into the stagnant water, forcing them to
breathe air. We're in ichthyostega. We can breathe air or water,
closing off our windpipe to switch between lungs and gills. Today,
our gills are gone, but the mechanism remains, and sometimes
times at spasms, giving us the hiccups three hundred and
sixty five million years ago. We stick our head out
of the water.
Speaker 2: There's a swamp.
Speaker 1: Behind us, paradise ahead. The choice is simple, but the
consequences are immense. We pull ourselves out of the water
and change the course of history. This is the moment
we leave the water for a new life on land.
But all this food comes at a price. The fierce
sun dries out our skin, the hard terrain tears at
our soft feet. Ichthyostega is a fish out of water.
We dodged extinction in a stagnant swamp, only to slam
straight into another deadly environment. Countless creatures perish, but natural
selection helps our ancestor adapt. Thicker skin protects us from
the sun, and tough claws that will one day become
our fingernails help us move across the rough terrain until
we're cassanaria. We've adapted to life on life, but our
eggs haven't. They need a tough shell to stop them
drying out in the sun. The problem is males can't
fertilize an egg through a tough shell, but they can
fertilize it before the shell forms inside the female's body.
Sex as we know it starts here. The result is
a masterpiece of evolution, an egg in a tough shell
with all the nutrients the embryo needs sealed inside. Sex
is the best way to increase genetic variety and keep
our species alive. Thanks to sex, three hundred and forty
million years ago, Casinaria becomes the first of our ancestors
to live entirely on land. It's a new world, different
from anything we've experienced up to now. We breathe air,
support our own weight, and wrestle with an onslaught of
new smells, sounds, sights, bombarded with information, our brains evolve.
We're smart, and we need to be. From that first
creature to set foot on land, millions of species have evolved.
More competitors mean less food to go round. A mutation
gives us bigger, more powerful jaw muscles. It's a critical advantage.
We can eat more food faster, and it shows we're Varnops,
a slab of pure meat eating power. This little creature
is a proterosaurus wants a competitor. Now he's prey with
Varyonops for an ancestor. Our success seems certain, but our
story is a rollercoaster ride, and there's a big dip coming.
Speaker 2: Two hundred and fifty.
Speaker 1: Million years ago, thousands of miles away in Siberia, the
Earth tears itself apart. A giant plume of magma surges
up from deep inside the planet. Molten rock oozes through
cracks in the Earth's crust, covering an area the size
of the United States under a layer one thousand feet deep,
and it continues for half a million years. Trillions of
tons of noxious carbon dioxide trapped the Sun's heat inside
the atmosphere, Temperatures soar to over one hundred degrees. Plants,
the plant eaters, and eventually the meat eaters perish. Ninety
five percent of all species die, only a tiny handful
hang off among them, us and another species that will
one day become the dinosaurs. As the fight for survival
winds down, the battle for supremacy begins. Thirty million years
since volcanic eruptions wiped out ninety five percent of all
living things. When the eruptions struck, we look like a
large lizard. Now we're a catsized creature covered in fur
called ectininion. Imagine you've survived the apocalypse, and today is
the day it's finally safe to venture out of hiding,
you discover.
Speaker 2: You're not alone.
Speaker 1: The last thing you want to see is a dinosaur,
a five foot tall Herrerasaurus. She evolved from one of
the small reptiles that survived the mass extinction. Her ancestors
adapted faster than ours, putting the dinosaurs ahead in the
game and leaving us playing ketchup. This one's fast, strong,
and hungry. We're staring down the barrel of an evolutionary gun.
Our only hope natural selection. Over millions of years, we
get smaller.
Speaker 2: So we're harder to catch.
Speaker 1: We become nocturnal, making us harder to see.
Speaker 2: We're cold and scared.
Speaker 1: Tiny muscles around the base of each hair contract making
our fur stand on end, trapping air as insulation. That's
why today, when we're cold or startled, we get goosebumps.
Our senses sharpened so we can see here and smell
a dinosaur before a dinosaur sees us. Inside our brain,
a new structure evolves, the neocortex, the home of complex
thought that allows us to analyze the situation and respond.
It will one day give us the power to imagine, create,
and communicate. Sixty six million years ago. We're Batadom, a
two inch long, shrewd like creature living on our wits
in the ancient forests of Montana. Humanity's future depends on
Badadan's sharp senses and supercharged brains. If these fail, we
may never exist. The dinosaurs may be the best thing
that ever happened to us. Thanks to them, we have
powerful senses and brilliant brains. Without them, we could still
be laying eggs to protect our offspring from hungry dinosaurs.
We evolved to give birth to live young. Instead of
leaving them to fend for themselves, we nurture them with milk.
Speaker 2: Sweat.
Speaker 1: Glens evolved to become mammary glands. It's a major milestone
in our journey from cell to human, the birth of
a new kind of animal, one that will branch out
into more than four thousand species, from the smallest mouse
to the largest whale. To us, the mammals have arrived.
The dinosaurs help shape who we are, but we lost
the battle for supremacy. The dinosaur's reign for over one
hundred and sixty five million years. Nothing can stop.
Speaker 3: Them, or so it seems.
Speaker 1: Montana, sixty five million years ago, an asteroid strikes eighteen
hundred miles away off Mexico's Yucatan Peninsula. A small rat
like mammal is about to face the fight of his life.
Lose and humans may never exist. Pulverized rock and dust
engulfed the entire planet, the only way out is to dig.
Smoke and ash from the fires block out the sun.
Temperatures plummet, vegetation dies. The local disaster becomes a global catastrophe.
For the dinosaurs, it's a disaster. They're big creatures with
big appetites, and now that's a big problem. As the
mighty fall, the small rise to the top. Bugs tough
enough to survive the worst catastrophe, gorge on the dead
and decaying, and they make the perfect snack. Next time
you're about to squash a bug, remember that we wouldn't
be here without them. Sixty four million years ago, our
bug eating ancestor is purgatorious, just under six inches long.
This little creature and the rest of his mammal family
are the unlikely inheritors of the dinosaur's crown. Mammals become
the dominant animals on land. They spread out across the
newly formed continents. Our future rests on their tiny shoulders
from the ashes of destruction. New life begins to sprout.
Sixty million years ago, fruit ripens on the trees, packed
full of nutrients. The more fruit we eat, the longer
we live. We leave solid ground for a new life
in the trees. A new world demands a new body.
We've come a long way from that first single cell. Now,
at last, we're beginning to glimpse of family resemblance. We're
alti at Lassius, one of the first members of a
new group of mammals, the primates.
Speaker 2: By fifty six million years.
Speaker 1: Ago, we've adapted to our world, but that world is
about to change again. Over ten million years, extreme temperature
shifts ravage the forests. Forests gets smaller, food gets harder
to reach. Natural selection intervenes again. Our tail shrinks back
to the base of the spine, where it stays as
the coccix, a reminder of our days spent leaping through
the trees. Instead of leaping, we stretch, our arms grow
long and flexible. Changing temperatures changed our ancestors and us forever,
but the planets not finished yet. Deep underground, the African
and Arabian plates pull apart the land between them drops
to form the East African Rift Valley. Along its edge,
a three and a half thousand mile long mountain shape
rises up rains from the Indian Ocean, once watered all
of Africa. Now the mountains block their path, The trees
get even further apart, the food harder to reach. We're starving, desperate.
Four point four million years ago. The will to survive
that's driven us from a single cell in the ocean
to a complex primate in the forests of Africa is
about to make us do something extraordinary, something no primate
has ever done before. After three billion years of evolution,
we hit an evolutionary dead end. We are Artipithecus ramidus,
four feet tall at eighty pounds, with a brain the
size of an orange. Our dense rainforest home has become
patchy forest. We can stand on branches move along them,
but to reach more food, we need to let go.
Four point four million years ago, these are our first
steps on two legs. Walking takes us to the food
and leaves our hands free to pick it.
Speaker 2: It catches on fast.
Speaker 1: Artipithecus is smart enough to copy and learn. Walking gets
past from parent to child. Over the next one point
two million years Our body evolves so that we can
walk further and faster. Finding shelter, a mate and food
gets easier, but childbirth gets harder. With a narrower pelvis,
giving birth to a fully developed infant becomes impossible. Babies
have to come out early when their heads are smaller
and they're barely developed.
Speaker 2: That's why we are.
Speaker 1: One of the few species to spend years caring for
our offspring, protecting them, feeding them, and keeping them out
of trouble. Three point two million years ago, we're an
Australo pitheken. Our brain is the size of a grapefruit,
and we walk on two legs all the time. We
got lucky, the lion has already eaten.
Speaker 2: This time.
Speaker 1: We can't outrun our predators. The only way to survive
is to outthink that the smarter we get, the.
Speaker 2: Longer we live.
Speaker 1: Natural selection promotes the mutations that improve.
Speaker 2: Our brain power. Your jaw muscles released from the.
Speaker 1: Muscle's vice like grip.
Speaker 2: The brain is free to grow.
Speaker 1: It doubles in size two point three million years ago.
This is Homo habilis, also known as handyman. Walking on
two legs with a big brain. We're the first of
an entirely new type of creature. We're the first man.
We're bigger, stronger, and hungry than ever before. There's food
out there, but it's more likely to eat us before
we can eat it. We're a scavenger working alone. We
eat whatever we can find. The edge is razor sharp.
We have just made the very first tool. Armed with this,
we will change.
Speaker 2: The world.
Speaker 1: East Africa two point three million years ago, after over
three billion years of evolution, we take our fate into
our own hands. We are the first species to make
tools in this hostile environment. We need every advantage we
can get. We must fight off predators, starvation, and our
own relatives. There's no meat left. It looks like we're
going hungry again. But there's bone marrow locked inside packed
within her. The tool is the key to a whole
new way of life. We'll use it to grow crops,
build cities, and travel into space. Our thumbs become stronger,
puld a cup, pick up a pen. We can do
this because two million years ago, tool use changed our
bodies and the course of evolution. We've pieced together our
ancestors story from their bones, but from the vastness of Africa.
All the bones of our early human ancestors ever found,
would fit into the back of a pick up. Less
than one bone in a billion becomes a fossil factor
in the chances of finding those bones across millions of
square miles, and it's clear most of what has lived.
Speaker 2: Has been lost.
Speaker 1: Our family tree is a giant puzzle with most of
the pieces missing. But one point eight million years ago,
a piece falls into place and we find a new
species on the scene, Homo erectus. Until this point we
were scavengers, but now we're hunters, and we've learned how
to work with other members of our species. The hunt
is on. The impala can run fast, but we can
run further. Low shoulders and long torsos stabilize us. Powerful
buttock muscles contract, expand, and push us forwards. Sweat stops
us from overheating. Covered in fur, the Impalla is exhausted.
Fire it sparks an idea that will make our ancestors
human warmth. Light, safety is within reach. Nature's power is
in our hands. Protected from the terrors of the dark,
our extended family gather round By working together, These earliest
families get food more often, so we live longer. This
is the advantage of family life, the reason most of
us live as we do today. Meat is too precious
to waste, and cooked meat is easier to chew. The
powerful molars used to chew tough raw food retreat back
into the gums, where they'll stay as our wisdom teeth.
Thirty five percent of us never even grow them, a
sign that they may be evolving out of existence. With
less energy spent on chewing, our ancestors have energy to spare.
The brain increases to the size of a softball, fifty
percent larger than before the invention of cooking. Erectus is
the cleverest, most cooperative ancestor to date, but with several
adult males in an extended family, rivalries are inevitable, communicate
and will live longer. A natural selection kicks in. Our tongue,
changes shape and moves down our throat, carrying the larynx
with it, allowing us to form different shapes in our mouths,
making different sounds and ultimately words. Speech is our greatest tool.
It's the last piece of the puzzle that turns our
ancestors into us. Two hundred thousand years ago, after a
three point three billion year battle for survival. We've arrived.
We are Homo sapiens, meaning wise men. Pound for pound,
we have the largest brain of any creature on Earth.
Speaker 2: Armed with tools, speech, and.
Speaker 1: Superior intelligence, we spread out across every continent, evolve and
adapt to new environments, new challenges, until we become the
undisputed masters of the world.