Digging for humanity's origins - Louise Leakey

[wind rushing, dramatic music]

[applause]

Who are we?

That is the big question,

and essentially,
we are just an upright, walking,

big-brained,
super-intelligent ape.

This could be us.

We belong
to the family called the Hominidae.

We are the species
called Homo sapiens sapiens,

and it's important
to remember that,

in terms of our place
in the world today

and our future on planet Earth.

We are one species

of about 5,500 mammalian species

that exist on planet Earth today,

and that's just a tiny fraction
of all species

that have ever lived on the planet
in past times.

We're one species
out of approximately, what?

Let's say
at least 16 upright walking apes

that have existed
over the past 6 to 8 million years.

But as far as we know,
we're the only upright walking ape

that exists on planet Earth today,

except for the bonobos,
and it's important to remember that

because the bonobos are so human

and they share 99% of their genes
with us,

and we share our origins

with a handful
of the living great apes.

It's important to remember
that we evolved.

Now, I know that's a dirty word
for some people,

but we evolved
from common ancestors

with the gorillas,

the chimpanzee,

and also the bonobos.

We have a common past,

and we have a common future.

And it is important to remember

that all of these great apes

have come on as long

and as an interesting
evolutionary journey

as we ourselves have today.

And it's this journey

that is of such interest
to humanity,

and it's this journey
that has been the focus

of the past three generations
of my family,

as we've been in East Africa,

looking for the fossil remains
of our ancestors

to try and piece together
our evolutionary past.

And this is how we look for them.

A group of dedicated
young men and women

walk very slowly off--

across vast areas of Africa,

looking for small fragments
of bone,

fossil bone,
that may be on the surface,

and that's an example
of what we may do

as we walk across the landscape
in northern Kenya,

looking for fossils.

I doubt many of you
in the audience

can see the fossil
that's in this picture,

but if you look very carefully,
there is a jaw, lower jaw

of a 4.1 million year old
upright walking ape

as it was found at Lake Turkana
on the west side.

It's extremely time consuming,
labor intensive,

and it is something that--

it's going
to involve a lot more people

to begin to piece
together our past.

We still really haven't
got a very complete picture of it.

When we find a fossil, we mark it.

Today we've got great technology,
we have GPS.

We mark it with a GPS fix,

and we also take a digital photograph
of the specimen,

so we could essentially
put it back on the surface,

exactly where we found it.

And we can bring
all this information

into big GIS packages today

When we then
find something very important,

like the bones
of a human ancestor,

we begin to excavate it
extremely carefully and slowly,

using dental picks
and fine paint brushes,

and all the sediment
is then put through these screens,

and we go again through it,
very carefully,

looking for small bone fragments.

It's then washed.

And these things are so exciting.

They are so often the only,

or the very first time that anybody
has ever seen the remains.

Here is a very special moment
when my mother and myself

were digging up some remains
of human-- human ancestors,

and it is one
of the most special things

to ever do with your mother.

[audience laughs]

And not many people can say that.

But now, let me take you
back to Africa,

2 million years ago.

I'd just like to point out,

if you look at the map of Africa,

it does actually look
like a hominid skull

in its shape.

Now we're going to go
to the East African--

and the Rift Valley,

which essentially
runs up from the Gulf of Aden

or runs down to Lake Malawi.

And the Rift Valley is a depression,
it's a basin,

and rivers flow down
from the highlands

into the, the basin
carrying sediment,

preserving the bones of animals
that lived there.

If you want to become a fossil,

you actually need to die somewhere

where your bones
will be rapidly buried.

You then hope that the earth
moves in such a way

as to bring the bones
back up to the surface,

and then you hope
that one of us lot will walk around

and find small pieces of you again.

So it is absolutely surprising

that we know as much
as we do know today

about our ancestors,

because it's incredibly difficult,

A, for these things to become--
to be preserved,

and secondly,

for them to have been brought
back up to the surface.

And we really
have only spent 50 years

looking for these remains

and begin to actually piece together
our evolutionary story.

So let's go to Lake Turkana,

which is one such lake basin

in the very north
of our country, Kenya.

And if you look north here,
there's a big river

that flows into the lake
that's been carrying sediment

and preserving the remains
of the animals that lived there.

Fossil sites run up and down
both lengths of that lake basin,

which represents
some 20,000 square miles.

That's a huge job
that we've got on our hands.

Two million years ago,
at Lake Turkana,

Homo erectus,
one of our human ancestors,

actually lived in this region.

You can see some
of the major fossil sites

that we've been working
in the north.

But essentially,
2 million years ago,

Homo erectus,
up in the far right corner,

lived alongside three other species

of human ancestor.

And here is a skull
of a Homo erectus

which I've just
pulled off the shelf there.

[audience laughs]

But it is not to say

that being a single species
on planet Earth is the norm.

In fact, if you go back in time,

it is the norm that there
are multiple species of hominids

or of human ancestors
that coexist at any one time.

Where did these things come from?

That's what we're still trying
to find answers to,

and it is important to realize

that there is diversity
in all different species,

and our ancestors are no exception.

There's some reconstructions
of some of the, the fossils...

that have been found
from Lake Turkana.

But I was very lucky
to have been brought up in Kenya,

essentially accompanying my parents
to Lake Turkana

in search of human remains,

and we were able to dig up,

when we got old enough,

fossils such as this,
a slender-snouted crocodile,

and we dug up giant tortoises,

and elephants,
and things like that.

But when I was 12,
as I was in this picture,

a very exciting expedition
was in place on the west side

when they found, essentially,

the skeleton of this Homo erectus.

I could relate
to this Homo erectus skeleton very well,

because I was the same age
that he was

when he died,

and I imagined him to be tall,

dark-skinned.

His brothers certainly
were able to run long distances

chasing prey,

probably sweating heavily
as they did so.

He was very able
to use stones effectively as tools.

And this individual himself,

this one that I'm holding up here,

actually had a bad back.

He'd probably
had an injury as a child.

He had a scoliosis, and therefore
must have been looked after

quite carefully by other female,

and probably much smaller,
members of his family group

to have got to where he did in life,
age 12.

Unfortunately for him,
he fell into a swamp

and was-- and couldn't get out.

He-- essentially,
his bones were rapidly buried

and beautifully preserved,
and he remained there

until 1.6 million years later,

when this very famous fossil hunter,
Kamoya Kimeu,

walked along a small hillside

and found that small piece
of his skull,

lying on the surface
amongst the pebbles,

recognized it as as being hominid.

It's actually this little piece
up here, on the top.

Well, an excavation
was begun immediately,

and more
and more little bits of skull

started to be extracted
from the sediment.

And what was so fun about it
was this the skull pieces

got closer and closer
to the roots of the tree,

and fairly recently the tree
had grown up,

but it had found that the skull

had captured nice water
in the hillside,

and so it had decided to grow its roots
in and around this,

holding it in place
and preventing it

from washing away downslope.

We began to find limb bones.

We found finger bones,

the bones of the pelvis,
vertebrae,

ribs, collarbones,

things that had never, ever
been seen before in Homo erectus.

It was truly exciting.

He had a body very similar
to our own,

and he was
on the threshold

of becoming human.

Well, shortly afterwards,
members of his species

started to move northwards
out of Africa,

and you start to see fossils
of Homo erectus in Georgia,

China,

and also in parts of Indonesia.

So Homo erectus
was the first human ancestor

to leave Africa and begin its spread
across the globe.

Some exciting finds,
again as I mentioned,

from Dmanisi
in the Republic of Georgia,

but also surprising finds from--
recently announced

from the island of Flores
in Indonesia,

where a group
of these human ancestors

have been isolated
and have become dwarfed,

and they're only
about a meter in height.

But they lived
only 18,000 years ago,

and that is truly extraordinary
to think about.

Just to put this
in terms of generations,

because people do find it hard
to think of time,

Homo erectus
left Africa 90,000 generations ago.

We evolved, essentially,
from an African stock, again,

at about 200,000 years,
as a fully fledged us.

And we only left Africa
about 70,000 years ago.

And until 30,000 years ago,

at least three upright walking apes

shared the planet Earth.

The question now is,
Well, who are we?

We're certainly a polluting,
wasteful, aggressive species

with a few nice things
thrown in, perhaps, [audience laughs]

but for the most part,
[audience laughs]

it's not particularly pleasant
at all.

We have a much larger brain
than our ancestors.

Is this a good evolutionary adaptation,

or is it going to lead us

to being
the shortest lived hominid species

on planet Earth?

And what is it
that really makes us, us?

I think
it's our collective intelligence.

It's our ability
to write things down,

our language
and our consciousness.

From very primitive beginnings

with a very crude toolkit
of stones,

we now have
a very advanced toolkit.

and our tool use has
really reached unprecedented levels.

We've got buggies to Mars.

We've mapped the human genome

and recently
even created synthetic life,

thanks to Craig Venter.

And we've also managed
to communicate

with people all over the world

from extraordinary places,

even from within an excavation
in northern Kenya,

we can talk to people
about what we're doing.

As Al Gore
so clearly has reminded us,

we have reached
extraordinary numbers

of people on this planet.

Human ancestors really
only survive on planet Earth,

if you look at the,
the fossil record,

for about,
on average, a million years at a time.

We've only been around
for the past 200,000 years

as a species,

yet we've reached a population
of more than 6.5 billion people.

And last year,
our population grew by 80 million.

I mean,
these are extraordinary numbers.

You can see here, again,
taken from Al Gore's book.

But what's happened
is our technology

has removed the checks
and balances on our population growth.

We have to control our numbers,

and I think this is as important

as anything else that's being done
in the world today.

But we have to control our numbers,

because we can't really hold it together
as a species.

My father so appropriately put it

that we are certainly the only animal
that makes conscious choices

that are bad for our survival
as a species.

Can we hold it together?

It's important to remember
that we all evolved in Africa.

We all have an African origin.

We have a common past

and we share a common future.

Evolutionary speaking,
we're just a blip.

We're sitting
on the edge of a precipice,

and we have the tools

and the technology at our hands

to communicate
what needs to be done

to hold it together today.

We could tell
every single human being

out there if we really wanted to.

But will we do that?

Or will we just let nature
take its course?

Well, to end
on a very positive note,

I think evolutionary speaking,

this is probably a fairly good thing
in the end.

I'll leave it at that,
thank you very much.

[applause]

[dramatic music]