There's something about caves.

A shadowy opening in a limestone cliff
that draws you in.

As you pass through the portal
between light and dark,

you enter a subterranean world.

A place of perpetual gloom,

a place of earthy smells,
of hushed silence.

Long ago in Europe,

ancient people also entered
these underground worlds.

As witness to their passage,

they left behind mysterious
engravings and paintings.

Like this panel of humans, triangles
and zig-zags from Ojo Guareña in Spain.

You now walk the same path
as these early artists.

And in this surreal, other-worldly place,

it's almost possible to imagine

that you hear the muffled foot-fall
of skin boots on soft earth,

or you see flickering of a torch
around the next bend.

When I'm in a cave,

I often find myself wondering,
what drove these people to go so deep?

to brave dangerous and narrow
passageways to leave their mark?

In this video clip,

that was shot half a kilometer,
or about a third of a mile underground,

in the cave of Curon in Spain,

we found a series
of red paintings on a ceiling

in a previously unexplored
section of the cave.

As we crawled forward, military-style,
with the ceiling getting ever-lower,

we finally got to a point
where the ceiling was so low,

that my husband and project
photographer, Dylan,

could no longer achieve focus
on the ceiling with his DSLR camera.

So while he filmed me,

I kept following the trail of red paint
with a single light,

and a point-and-shoot camera
that we kept for that type of occasion.

Half a kilometer underground.

Seriously.

What was somebody doing down there
with a torturous stone lamp?

(Laugher)

I mean --me, it makes sense, right?

But you know,

this is the kind of question that
I'm trying to answer with my research.

I study some of
the oldest art in the world.

It was created by these
early artists in Europe,

between 10 thousand
and 40 thousand years ago.

And the thing is,

is that I'm not just studying it
because it's beautiful,

though some of it certainly is.

But what I'm interested in
is the development of the modern mind,

of the evolution of creativity,
of imagination, of abstract thought.

About what it means to be human.

While all species communicate
in one way or another,

only we humans have really taken it
to another level.

Our desire and ability
to share and collaborate,

has been a huge part of out success story.

Our modern world is based on a global
network of information exchange.

Made possible, in large part,
by our ability to communicate.

In particular, using graphic
or written forms of communication.

The thing is though,

that we've been building
on the mental achievements

of those that came before us for so long,

that it's easy to forget that certain
abilities haven't already existed.

It's one of the things
I find most fascinating

about studying our deep history.

Those people didn't have the shoulders
of any giants to stand on,

they were the original shoulders.

And while a surprising number
of important inventions

come out of that distant time,

what I want to talk to you about today
is the invention of graphic communication.

There are three
main types of communication,

spoken, gestural -- 
so things like sign language,

and graphic communication.

Spoken and gestural are,
by their very nature, ephemeral.

It requires close contact for a message
to be sent and received.

And after the moment of transmission,
it's gone forever.

Graphic communication, on the other hand,
decouples that relationship,

and with its invention, it became possible
for the first time,

for a message to be
transmitted and preserved,

beyond a single moment in place and time.

Europe is one of the first places

that we start to see graphic marks
regularly appearing

in caves, rock shelters, and even
a few surviving open air sites.

But this is not the Europe we know today.

This was a world dominated
by towering ice sheets

by towering ice sheets, three to four
kilometers high,

with sweeping grass plains
and frozen tundra.

This was the Ice Age.

Over the last century,

more than 350 Ice Age rock art sites
have been found across the continent.

Decorated with animals, abstract shapes,
and even the occasional human.

Like these engraved figures
from Grotta dell'Addaura in Sicily.

They provide us with a rare glimpse
into the creative world

into the creative world and imagination
of these early artists.

Since their discovery,

it's been the animals that have received
the majority of the study.

Like this black horse from 
, Spain.

Or this unusual purple bison
from La Pasiega.

But for me, it was the abstract shapes,
what we call geometric signs,

that drew me to study the art.

The funny this is, that at most sights,

the geometric signs far outnumber
the animal and human images.

But when I started on this back in 2007,

there wasn't even a definitive list
of how many shapes there were,

nor was there a strong sense

of whether the same ones appeared
across space or time.

Before I could even
get started on my questions,

my first step was to compile a database

of all known geographic signs
from all of the rock art sites.

The problem was that while they were
well documented at some sights,

usually the ones
with the very nice animals,

there was also a large number of them
where it was very vague --

there wasn't a lot
of description or detail.

Some of them hadn't been visited
in half a century, or more.

These were the ones
that I targeted for my field work.

Over the course of two years,

my faithful husband Dylan and I
each spent over 300 hours underground,

hiking, crawling and wriggling
around 52 sites

in France, Spain, Portugal and Sicily.

And it was totally worth it.

We found new, undocumented geometric signs
at 75 percent of the sites we visited.

This is the level of accuracy
I knew I was going to need

if I wanted to start answering
those larger questions.

So let's get to those answers.

Barring a handful of outliers,
there are only 32 geometric signs.

Only 32 signs across
a 30 thousand year time span,

and the entire continent of Europe.

That is a very small number.

Now if these were random
doodles or decorations,

we would expect to see
a lot more variation,

but instead what we find
are the same signs,

repeating across both space and time.

Some signs start out strong,
before losing popularity and vanishing,

while other signs are later inventions.

But 65 percent of those signs stayed
in use during that entire time period.

Thigns like lines, rectangles, trianagles,
ovals and circles.

Like we see here
from the end of the Ice Age

at a 10 thousand-year-old site,
high in Pyrenees Mountains.

And while certain signs span
thousands of kilometers,

other signs had restricted
distribution patterns,

with some being limited
to a single territory,

like we see here with these
divided rectangles

that are only found in northern Spain,

and what some researchers have speculated

could be some sort
of family or clan signs.

On a side note,

there is surprising degree similarity
in the earliest rock art

found all the way from France and Spain
to Indonesia and Australia.

With many of the same signs
appearing in such far-flung places,

especially in the 30 thousand
to 40 thousand-year range,

it's starting to seem increasingly likely

that this convention actually traces back
to a common point of origin in Africa,

but that I'm afraid, is a subject
for a future talk.

So back to the matter at hand.

There could be no doubt that these signs
were meaningful to their creators,

like these 25 thousand-year-old
___________ sculptures

from La Roque de Venasque in France.

We might not know what they meant
but the people of the time certainly did.

The repetition of the same signs,
for so long, and at so many sites,

tells us that the artists
were making intentional choices,

If we're talking about geometric shapes,

with specific, culturally recognized,
agreed upon meanings,

than we could very well be looking

at one of the oldest systems of graphic
communication in the world.

I'm not talking about writing yet.

There's just not enough
characters at this point,

to have represented all of the words
in the spoken language,

something which is a requirement
for a full writing system.

Nor do we see the signs
repeating regularly enough

to suggest that they were
some sort of alphabet.

But what we do have
are some intriguing one-offs

like this panel from La Pasiega in Spain
known as "The Inscription",

with its symmetrical markings on the left,

possible stylized representations
of hands in the middle,

and what looks a bit like
a bracket on the right.

The oldest systems of graphic
communication in the world --

Sumerian cuneiform, Egyptian hieroglyphs,
the earliest Chinese script,

all emerged between four thousand
and five thousand years ago,

with each coming into existence
from an earlier protosystem

made of counting marks
and pictographic representations,

where the meaning
and the image were the same.

So a picture of a bird would really have
represented that animal.

It's only later that we start to see
these pictographs become more stylized,

until they almost become unrecognizable.

And that we also start to see

more symbols being invented to represent
all those missing words in the language --

things like pronouns, adverbs, adjectives.

So knowing all this,

it seems highly unlikely the geometrics
signs from Ice Age Europe

were truly abstract written characters.

Instead what's much more likely

is that these early artists
were also making counting marks,

maybe like this row lines
from Reparo de Za Minica in Sicily,

as well as creating stylized
representations

of things from the world around them.

Could some of the signs
be weaponry or housing?

Or what about celestial objects
like star constellations?

Or maybe even rivers, mountains,
trees-- landscape features.

Possibly like this black peniform
surrounded by strange bell-shaped signs

from the site of El Castillo, in Spain.

The term peniform means
"feather-shaped" in Latin,

but could this actually be
a depiction of a plant or a tree?

Some researchers have begun

to ask these questions
about certain signs at specific sites,

but I believe the time has come
to revisit this category as a whole.

The irony in all of this, of course,

is that having just carefully classified
all the signs into a single category,

I have a feeling that my next step
will involve breaking it back apart

as different types of imagery
are identified and separated off.

Now don't get me wrong,

the later creation
of fully-developed writing

was an impressive feat in its own right,

but it's important to remember

that those early writing systems
didn't come out of a vacuum.

And that even five thousand years ago,

people were already building
on something much older,

with its origins stretching back
tens of thousands of years --

to the geometric signs
of Ice Age Europe and far beyond,

to that point, deep in our
collective history,

when someone first came up with the idea
of making a graphic mark,

and forever changed the nature
of how we communicate.

Thank you.

(Applause)