to find her distant ancestor, Bob.

Now, up until this time, human culture

was relatively unsophisticated --

utilizing the same primitive stone tools

which went unchanged for thousands of years.

But somewhere around 50,000 years ago,

something interesting happened.

And nobody knows, for sure, why.

There was a sudden explosion of diverse cultural artifacts,

including instruments for making music, new tools,

and other forms of creative expression.

Humans developed the ability

to externalize their inner thoughts.

They began to communicate using language.

So, Alice begins her search by looking for water.

She knows that human and animal populations

tend to migrate towards and along rivers,

which are the life blood of ecosystems.

Eventually, she comes across an interesting marking --

Bob's handprint.

This marking contains very little information.

Simply that he was here, and could possibly return.

Alice knows Bob is equally intelligent.

He can communicate orally --

although his culture has not yet developed

the ability to read or write in [its] native language.

At the time, the universal written language was art.

So she finds natural materials around her,

to paint him a picture, in case he returns.

She renders an animal she is tracking,

hoping this will offer a clue

about the direction she is traveling in the future.

Our ancestors used natural materials

to create pictorial representations of their reality.

Here is an actual cave painting --

from around 30,000 years ago --

found preserved deep inside Chauvet cave, in France.

Similar renderings are found in the caves of Spain as well.

A common theme among these ancient paintings

[is] animal forms, as well as the human hand --

perhaps as a signature, a story, or a ritual calling.

When Bob returns to the waterfall, he finds her painting,

and proceeds towards the river,

where he thinks she might be.

When he arrives, he does not find her --

though he finds a sign that she was here before.

He decides to paint her a picture,

explaining where he is going next,

which is half-way up the river, towards the setting sun.

He has little time to paint the picture, as night is approaching.

Therefore, he needs a fast way to visualise his message.

He thinks about it for a moment,

and realizes his message only contains

three distinct mental objects:

'middle' -- 'river' -- 'west'

So he decides to use simplified pictures to represent them.

For 'river,' he draws a symbol

which resembles [a river's] natural form --

known as a 'pictogram' -- which is a drawing

that resembles the physical object it represents.

Pictograms are an important step in the evolution of writing.

Here is a ceremonial slate palette, found in Egypt,

dated before 3,000 BC.

The surrounding scene shows a struggle

between civilized humans

and the wild and ferocious animals.

However, it's difficult to draw pictures

of abstract concepts -- such as 'calm,' 'old,' 'dangerous' --

or, in Bob's case, 'middle.'

For this, he draws a line with a box over the middle.

It represents 'half way.'

This is known as an 'ideogram' --

or a conceptual picture of an abstract idea.

Here is an example of the same symbol

on an ancient Chinese bronze inscription.

For the idea of 'west,'

he decides on a picture of the setting sun.

Now he does something interesting.

He combines these individual symbols --

in terms of their meaning -- to create a message.

Meaning plus meaning equals new meaning.

He leaves this in hope of Alice finding it.

Some of the earliest artifacts of this symbolic merging

are found in ancient Mesopotamia -- now modern Iraq --

home of the Sumerians.

This is the birthplace

of many of the world's earliest civilizations.

Here we find clay accounting tablets, which are some of

the oldest written documents ever found --

some dating before 3,000 BC.

The rectangular tablets record the payments in cattle,

shipments of cattle to shepherds for fattening,

and gifts of cattle as an offering.

Notice that, instead of drawing a picture of ten sheep,

they draw a symbol representing '10' --

using small notches --

and another symbol representing 'sheep' or 'donkey,'

meaning, simply, '10 sheep.'

We call this 'proto-writing.'

Finally, Alice returns to the base of the river,

and finds Bob's message.

She interprets the meaning correctly:

'half-way, west, down the river.'

So, she marches down river, towards the setting sun,

and eventually they finally meet.

Over time, Bob learns to speak Alice's language,

allowing them to use the same oral language

to communicate shared concepts and ideas.

This gives them an idea --

the root of a more powerful written language.

It starts with something very simple -- writing her name.

She disassociates the sound from the picture,

for her name, Alice.

(Alice ... Al -- ice)

She combines the mathematical symbol for 'all'

and the picture of 'ice.'

'All ice.'

'al-ice.'

Notice her name has nothing to do

with the individual symbols.

Sound plus sound equals new meaning.

This is known as the 'Rebus principle.'

A great example of this was found in Egypt,

along the Nile river.

Dated to aroung 3100 BC, it contains some of the

earliest hieroglyphic insciptions ever found.

'The Narmer Pallette' depicts

the Egyptian pharaoh, 'Narmer.'

On the back, we see him to the left of a kneeling prisoner,

who is about to be struck down by Narmer --

who we see standing tall, wearing a crown.

What we are looking for is on the other side.

Between the two bovine heads at the top,

we see an inscription of his name.

It's written as a fish and a chisel --

which translates to 'Nar Mer' --

'Narmer.'

Two sounds -- separated from the pictures --

together, giving new meaning --

a key development in the history of written language.

But before they could advance

towards what we know of as an 'alphabet,'

something had to happen.

They needed to save time.