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This is the story of how we are different

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to every other creature
that's ever walked the earth...

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...and the key to its telling lies with your family.

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That's my mother when she was four.
That's one generation ago.

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Look at the sulky face.

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She sulks like I do -
she'd just run away from home.

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And there's my grandfather
wearing his major's uniform.

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This would have been about 1916,
the time of the First World War.

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Then over the page, we've got my grandmother

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with her mother Julia, my great-grandmother.

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That's three generations ago.

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But supposing we could go back
not just one generation,

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or two generations, or even three generations,

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but three hundred generations...

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...or three thousand...

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...to an ancestor who shared
the world with the Neanderthals?

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Jump back sixty thousand generations

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and we'd meet one of the first people
to ever set foot outside Africa.

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A hundred thousand generations,

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and meeting the relatives
would be even more intimidating

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than you could ever have imagined!

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And that's just what we are going to do -
travel through time

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to meet the creatures who have become us,

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to see how their lives have led
to the amazing reality of ours.

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Our dead ancestors have left us
a key to unlock the past.

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With their fossil bones and relics as a guide...

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...scientists can build up a picture

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of what it would be like to travel back in time.

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If all the apeman fossils in the world
were collected together,

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I could probably fit the whole lot
in the back of this car.

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Yet each little fragment tells a tale
about the world of which it was once a part.

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These tiny pieces hold secrets
not only to how our ancestors died...

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...but to how they lived...

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...from our closest cousins, the Neanderthals,

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to the first fierce Europeans...

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...from our ancestors with the wit
to survive in the jungles of Asia...

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...to the first true families
who worked together in sun-baked Africa.

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We're journeying back in time,

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revealing the secret ingredients
that make you and me unique,

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and meeting the first creatures to have them -

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the earliest toolmakers,

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the heavyweight contenders
who shaped our past...

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...right back to see for ourselves
how you and I came to be.

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The first clear place
our fossil guide takes us is here.

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We've travelled three
and a half million years into our past,

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as science sees it,

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to meet a creature who began
the journey from ancient apes to us,

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in Africa... in this tree.

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This is your distant relative
from 300,000 generations ago -

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<i>Australopithecus afarensis.</i>
They're nesting for the night.

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This one has a special role
in the story of you and me.

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We'll call her Lucy.
She's special to someone else as well -

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her infant, born a few days ago.

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Lucy's troop is engaged in a turf war -

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a potentially violent territorial dispute.

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In the morning, it will change their lives forever.

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For afarensis, like apes of any time,

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filling up with water
is an important mission of the morning.

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But there is something that sets
these creatures apart from other apes -

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the first step on the journey to us.

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They can stand and walk on two legs.

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This is the troop's most senior male.

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He's also the father of Lucy's infant.

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He is 25 years old and in his prime.

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He could live as long as fifty years.

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That's <i>ancylotherium,</i> a cousin of the rhino.

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In this prehistoric world,

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it's the leader's strength
that holds the troop together.

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But if you think standing on two legs

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makes our ancestors king of the jungle,
then you're wrong.

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Aside from walking upright,

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there's nothing very remarkable
about these creatures at all.

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They are as subject to the laws
of nature as everything else.

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Yet Lucy and her kind
are the ancestors of you and me.

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To discover exactly what makes them so special,

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we must watch them rather more closely.

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Lucy is twenty-two.

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She's mother not only to her new infant,

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but to several others in the troop,
including this adolescent female...

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...who also makes a handy babysitter.

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(WHOOPING CRY)

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The sound is an unsettling one.
It's afarensis - but a rival troop.

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Several times, Lucy's troop's
territory has been invaded

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in a battle for its rich pickings.

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Losing their leader presents another problem -

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two males are contenders for the throne.

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He is the quiet man of the troop,
dependable and solid...

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...whilst he is brash and impulsive.

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Now they're driven to work together.

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A patrol party must be organized -

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and the males will rouse themselves
into a frenzy of display to form one.

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An afarensis troop has a territory
much like a modern chimp's -

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perhaps ten square miles,
bounded by rivers and mountains.

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Though the adults know their way around well,

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a crossroads is a flashpoint
for the leadership battle to begin.

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The first skirmishes are noisy displays.

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(GRUNTING)

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The eventual winner will gain respect,

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and privileged access to the troop's females.

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Meanwhile, the rival troop
is surprisingly close by.

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These reed beds form the overlap

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between the neighbouring afarensis territories.

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Normally, neither troop comes here,
as it isn't good for fruits and food...

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...but these intruder males
are on the trail of something different...

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...Lucy. Probably while foraging nearby,
she's disturbed them.

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An isolated afarensis is always vulnerable.

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The intruder males will seek them out

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and attack them to warn off their troop.

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At just over a metre tall,

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a female like Lucy is an easy target.

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If they found her now,
they'd almost certainly kill her.

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It's a lucky escape.

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With the trail cold, the intruder males move on.

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The river marks their southernmost
borders with Lucy's troop's land.

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It also makes a handy refreshment stop.

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And not only for the intruders.

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By pure chance, the patrol party
from Lucy's troop have also stopped by

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for a drink.

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As with rival apes of any time,
the encounter provokes a face-off.

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(AGGRESSIVE GRUNTING AND SCREECHING)

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With the water between them,
actual bloodshed is unlikely.

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Instead, displays of noise and power
are the order of the day...

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...which is lucky for Lucy's males,
as the intruders have arrived in numbers.

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If they were to meet on different ground,

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one might see a pretty uneven fight.

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The more you watch these creatures,
the more like apes they seem,

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so why, in the one crucial aspect,
are they so very unlike apes?

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What on earth could have happened
to make an ape stand upright

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and walk on two legs?

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Well, what happened is...

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...the world changed.

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Come with me and travel
even further back in time,

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before even afarensis was around...

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four, five, six million years ago, and further still.

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We're still in Africa,
but it's eight million years ago...

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...and home to the tree-living
ancestor of Lucy and her kind.

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We've never found any fossil evidence
of these mysterious apes,

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yet we know a few vital things about them.

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We know that, like the apes in modern times,

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they use their hands as well as their feet
to help them get around.

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We know that because it's the only way
to get around in their dense forest home.

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And how do we know this forest is their home?

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Because this forest is everywhere!

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Eight million years ago,

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Africa is covered in thick forest
almost from edge to edge,

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and it's the forest and what happens to it

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that holds the secret
to why an ancient tree-swinging ape

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was transformed into a two-footed afarensis.

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The shift from creatures
who move around on four limbs

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to those that walk about on two

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is so dramatic that it can only be achieved

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by an equally dramatic change
in the world around them.

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And that change is being driven
from thousands of miles away,

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deep beneath the sea.

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Here, the ocean floor is expanding.

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At about the speed that fingernails grow,

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the earth itself is on the move.

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It's changing the face of the planet.

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A vast chunk of the earth's crust
has been pushed to the north.

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One day, we'll know it as India.

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Deep underground, as it collides with Asia,

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it creates a twisted mass of rock.

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Five miles high and three thousand
miles long: The Himalayas.

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The mountains are having
an extraordinary effect on the weather.

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They've prompted some
of the heaviest storms ever seen -

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the monsoons.

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The rains strip the air of moisture,

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so that the air currents that reach Africa

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are not wet but dry.

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Rainforests retreat and a new world is created.

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Over millions of years, a landscape
of scattered trees takes shape.

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And something else has changed the scenery.

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A vast chasm,

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the great Rift Valley,
has ripped down one side of Africa.

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Everything from beetles to apes

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has had to keep pace
with this incredible change.

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Our tree-swinging ancestors
have evolved and transformed.

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Forced to spend more time on the ground,

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they've become the upright walking
afarensis we've met, like Lucy.

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But why use only two feet
to get around on the ground?

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It's easy to think that being
upright brings obvious advantages.

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Lucy can stand taller and see further...

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...but that also means
everything else can see her.

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It's a black eagle,

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an expert aerial hunter. An adult
afarensis is too big to take on...

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...but where there are adults, there are infants.

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Two legs have, in fact,
made Lucy neither quicker nor safer.

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So what is the advantage to afarensis

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of walking upright in this new world?

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The truth is, walking on two legs

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became a defining feature of my life and yours

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for the most surprising of reasons.

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Ultimately, it's all about sex.

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The males have returned from their patrol.

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00:19:39,760 --> 00:19:43,753
They must have tired
of their face-off with the intruders.

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00:19:47,040 --> 00:19:51,033
With security looked after,
it's an opportunity for the troop

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to get about the serious business
of grooming and building relationships.

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With Lucy's regular mate gone,
she attracts immediate attention.

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00:20:07,200 --> 00:20:11,273
It's one of the leadership contenders -
the quiet one.

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In the natural world,

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sex and raising babies
is the key to a species surviving...

202
00:20:25,080 --> 00:20:29,870
...so that anything that gives you
extra energy to do it better

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is like gold dust...

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00:20:33,160 --> 00:20:38,029
...and extra energy is what walking
upright has given afarensis.

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00:20:38,200 --> 00:20:43,274
In this mix of trees and grass, walking on two
legs is more efficient than walking on four.

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00:20:46,200 --> 00:20:51,433
The energy saved by changing
from a four-legged way of life is tiny.

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00:20:51,600 --> 00:20:55,434
The total number of calories
saved by afarensis in a year

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00:20:55,600 --> 00:21:00,913
is probably no more than that found
in a packet of chocolate biscuits.

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00:21:03,000 --> 00:21:06,037
But even such a tiny amount
makes a difference.

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Lucy is able to recover
that bit quicker after giving birth.

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00:21:21,240 --> 00:21:25,916
It could mean, in a lifetime,
she could raise just one more baby.

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00:21:28,480 --> 00:21:31,677
And one more baby might be the difference

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00:21:31,840 --> 00:21:35,992
between survival of the species and extinction.

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00:21:43,800 --> 00:21:48,191
The rival troop are on the move again,
this time from the west,

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00:21:48,360 --> 00:21:49,839
and once again,

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00:21:50,000 --> 00:21:52,719
patrolling takes priority.

217
00:21:56,000 --> 00:21:59,197
But not all the males are going to investigate.

218
00:22:01,200 --> 00:22:06,274
It's the brash would-be leader.
He, too, has his eye on Lucy.

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00:22:09,760 --> 00:22:13,912
All the attention is not simply to do with sex.

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00:22:14,080 --> 00:22:19,313
To become the dominant male,
he needs the support of the troop...

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00:22:20,800 --> 00:22:25,954
...and any chance to be alone
with a high-ranking female like Lucy

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00:22:26,120 --> 00:22:28,395
is not to be squandered.

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00:22:37,440 --> 00:22:39,908
But his advances catch Lucy unawares,

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and his position between Lucy
and her baby adds to her alarm.

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00:22:47,120 --> 00:22:50,112
Suddenly, the situation is out of control.

226
00:22:50,280 --> 00:22:53,113
It's become a fight for leadership.

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00:22:53,960 --> 00:22:57,999
(SHRIEKS AND GRUNTS)

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00:22:59,880 --> 00:23:02,269
The fight takes an unexpected twist.

229
00:23:02,440 --> 00:23:05,591
The brash contender grabs Lucy's infant.

230
00:23:05,760 --> 00:23:09,753
Whatever he hopes to achieve,
the stakes are raised dangerously.

231
00:23:29,240 --> 00:23:34,439
It's the rival troop. They've come
right into Lucy's troop's territory.

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00:23:51,480 --> 00:23:55,996
With the new enemy surrounding them,
the infant is instantly forgotten...

233
00:23:58,040 --> 00:24:00,315
...except, of course, by Lucy.

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00:25:21,800 --> 00:25:23,791
It's Lucy.

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00:25:27,400 --> 00:25:32,952
An ape, not particularly clever,
not particularly quick,

236
00:25:33,120 --> 00:25:36,157
with only a small advantage in energy use,

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00:25:36,320 --> 00:25:40,916
who lived and died without ceremony
here in the African bush.

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00:25:41,080 --> 00:25:43,594
It's not much of an epitaph,

239
00:25:43,760 --> 00:25:47,833
but Lucy has begun the journey to you and me.

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00:25:49,160 --> 00:25:53,233
Her hands were in life
little more than climbing tools,

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00:25:53,400 --> 00:25:58,474
but in generations to come,
they'll find a million uses.

242
00:25:59,400 --> 00:26:03,313
They'll search out food for a growing brain

243
00:26:03,480 --> 00:26:07,393
and one day make tools
to change the world around them.

244
00:26:09,000 --> 00:26:12,549
And, freed from the task of helping her move,

245
00:26:12,720 --> 00:26:16,713
the muscles of her chest
will help her descendants to speak.

246
00:26:17,920 --> 00:26:19,911
Dee!

247
00:26:20,080 --> 00:26:22,275
A-wah.

248
00:26:25,600 --> 00:26:28,797
Her adaptation, standing on two feet,

249
00:26:28,960 --> 00:26:31,713
opens doors for the future.

250
00:26:33,000 --> 00:26:38,677
She is, indeed, just an ape,
but an ape with potential.

251
00:26:42,480 --> 00:26:44,948
Knowing that her story will end in us,

252
00:26:45,120 --> 00:26:48,396
is there anything else
we can see in these creatures

253
00:26:48,560 --> 00:26:50,516
that we will one day inherit?

254
00:26:51,040 --> 00:26:52,598
Perhaps.

255
00:26:54,400 --> 00:26:56,118
Is it something like love

256
00:26:56,280 --> 00:26:59,829
which keeps this baby clinging
to its dead mother's fur?

257
00:27:00,000 --> 00:27:02,036
(SHRIEKING)

258
00:27:02,200 --> 00:27:04,953
Is it the beginnings of what we know as grief

259
00:27:05,120 --> 00:27:08,430
that you can hear in the troop's strange calls?

260
00:27:12,800 --> 00:27:16,873
Certainly, there's some behaviour
we'd like to think of as human.

261
00:27:19,440 --> 00:27:21,556
It's Lucy's elder daughter.

262
00:27:21,720 --> 00:27:24,757
She's come for the baby.

263
00:27:24,920 --> 00:27:29,994
If she adopts it within the troop,
there's a chance it might survive.

264
00:27:37,080 --> 00:27:41,870
These creatures have taken
the first step on our human journey.

265
00:27:45,720 --> 00:27:48,996
In a few hours' time, it'll rain.

266
00:27:49,160 --> 00:27:52,709
The waters will rise and will claim her body...

267
00:27:52,880 --> 00:27:57,908
...and in just over three million years,
she'll be found.

268
00:27:58,080 --> 00:28:02,551
In 1974, scientists will dig up
her fossilized bones,

269
00:28:02,720 --> 00:28:06,952
and will call her after the song
playing on their radio at the time -

270
00:28:07,120 --> 00:28:11,398
"Lucy in the Sky with Diamonds",
by The Beatles...

271
00:28:16,400 --> 00:28:20,279
...and Lucy and her kind
will set the world alight,

272
00:28:20,440 --> 00:28:22,954
not because of what they are now,

273
00:28:23,120 --> 00:28:26,590
but for what they will make possible.