0:00:00.760,0:00:02.600
There's something about caves --

0:00:04.560,0:00:08.840
a shadowy opening in a limestone[br]cliff that draws you in.

0:00:09.800,0:00:13.456
As you pass through the portal[br]between light and dark,

0:00:13.480,0:00:16.015
you enter a subterranean world --

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a place of perpetual gloom,[br]of earthy smells, of hushed silence.

0:00:22.800,0:00:24.136
Long ago in Europe,

0:00:24.160,0:00:27.616
ancient people also entered[br]these underground worlds.

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As witness to their passage,

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they left behind mysterious[br]engravings and paintings,

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like this panel of humans, triangles[br]and zigzags from Ojo Guareña in Spain.

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You now walk the same path[br]as these early artists.

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And in this surreal, otherworldly place,

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it's almost possible to imagine

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that you hear the muffled footfall[br]of skin boots on soft earth,

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or that you see the flickering of a torch[br]around the next bend.

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When I'm in a cave,

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I often find myself wondering[br]what drove these people to go so deep

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to brave dangerous and narrow[br]passageways to leave their mark?

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In this video clip,

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

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in the cave of Cudon in Spain,

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we found a series[br]of red paintings on a ceiling

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in a previously unexplored[br]section of the cave.

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

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we finally got to a point[br]where the ceiling was so low

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that my husband[br]and project photographer, Dylan,

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

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So while he filmed me,

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I kept following the trail of red paint[br]with a single light

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

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Half a kilometer underground.

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Seriously.

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What was somebody doing down there[br]with a torch or a stone lamp?

0:01:52.864,0:01:54.056
(Laughter)

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

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But you know,

0:01:57.240,0:02:01.056
this is the kind of question that[br]I'm trying to answer with my research.

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I study some of the oldest[br]art in the world.

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It was created by these[br]early artists in Europe,

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between 10,000 and 40,000 years ago.

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And the thing is

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that I'm not just studying it[br]because it's beautiful,

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though some of it certainly is.

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

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of the evolution of creativity,[br]of imagination, of abstract thought,

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about what it means to be human.

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While all species communicate[br]in one way or another,

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only we humans have really[br]taken it to another level.

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Our desire and ability[br]to share and collaborate

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has been a huge part of our success story.

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Our modern world is based on a global[br]network of information exchange

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made possible, in large part,[br]by our ability to communicate --

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in particular, using graphic[br]or written forms of communication.

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The thing is, though,

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that we've been building[br]on the mental achievements

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of those that came before us for so long

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

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It's one of the things[br]I find most fascinating

0:03:11.160,0:03:13.736
about studying our deep history.

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Those people didn't have the shoulders[br]of any giants to stand on.

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They were the original shoulders.

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And while a surprising number[br]of important inventions

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come out of that distant time,

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

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There are three[br]main types of communication,

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spoken, gestural --[br]so things like sign language --

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and graphic communication.

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Spoken and gestural are[br]by their very nature ephemeral.

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

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

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Graphic communication, on the other hand,[br]decouples that relationship.

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And with its invention,[br]it became possible for the first time

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for a message to be[br]transmitted and preserved

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beyond a single moment in place and time.

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Europe is one of the first places

0:04:06.600,0:04:09.296
that we start to see graphic marks[br]regularly appearing

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in caves, rock shelters[br]and even a few surviving open-air sites.

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But this is not the Europe we know today.

0:04:16.800,0:04:19.776
This was a world dominated[br]by towering ice sheets,

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three to four kilometers high,

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with sweeping grass plains[br]and frozen tundra.

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This was the Ice Age.

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Over the last century,

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more than 350 Ice Age rock art sites[br]have been found across the continent,

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decorated with animals, abstract shapes[br]and even the occasional human

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like these engraved figures[br]from Grotta dell'Addaura in Sicily.

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They provide us with a rare glimpse

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into the creative world and imagination[br]of these early artists.

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Since their discovery,

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it's been the animals that have received[br]the majority of the study

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like this black horse[br]from Cullalvera in Spain,

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or this unusual purple bison[br]from La Pasiega.

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

0:05:08.280,0:05:09.880
that drew me to study the art.

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The funny this is that at most sites

0:05:13.560,0:05:18.056
the geometric signs far outnumber[br]the animal and human images.

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But when I started on this back in 2007,

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

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nor was there a strong sense

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of whether the same ones[br]appeared across space or time.

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Before I could even[br]get started on my questions,

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my first step was to compile a database

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of all known geometric signs[br]from all of the rock art sites.

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The problem was that while they were[br]well documented at some sites,

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usually the ones[br]with the very nice animals,

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

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there wasn't a lot[br]of description or detail.

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Some of them hadn't been visited[br]in half a century or more.

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

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Over the course of two years,

0:06:01.840,0:06:07.056
my faithful husband Dylan and I[br]each spent over 300 hours underground,

0:06:07.080,0:06:11.056
hiking, crawling and wriggling[br]around 52 sites

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in France, Spain, Portugal and Sicily.

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And it was totally worth it.

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

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

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if I wanted to start answering[br]those larger questions.

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So let's get to those answers.

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

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Only 32 signs

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across a 30,000-year time span[br]and the entire continent of Europe.

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That is a very small number.

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Now, if these were random[br]doodles or decorations,

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we would expect to see[br]a lot more variation,

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but instead what we find[br]are the same signs

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repeating across both space and time.

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Some signs start out strong,[br]before losing popularity and vanishing,

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while other signs are later inventions.

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But 65 percent of those signs stayed[br]in use during that entire time period --

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things like lines, rectangles[br]triangles, ovals and circles

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like we see here[br]from the end of the Ice Age,

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at a 10,000-year-old site[br]high in the Pyrenees Mountains.

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And while certain signs[br]span thousands of kilometers,

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other signs had much more[br]restricted distribution patterns,

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with some being limited[br]to a single territory,

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like we see here[br]with these divided rectangles

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that are only found in northern Spain,

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and which some researchers have speculated

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could be some sort[br]of family or clan signs.

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On a side note,

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there is surprising degree[br]of similarity in the earliest rock art

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

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

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especially in that 30,000[br]to 40,000-year range,

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it's starting to seem increasingly likely

0:07:57.520,0:08:02.376
that this invention actually traces back[br]to a common point of origin in Africa.

0:08:02.400,0:08:05.016
But that I'm afraid,[br]is a subject for a future talk.

0:08:05.040,0:08:06.856
So back to the matter at hand.

0:08:06.880,0:08:10.856
There could be no doubt that these signs[br]were meaningful to their creators,

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like these 25,000-year-old[br]bas-relief sculptures

0:08:13.720,0:08:16.336
from La Roque de Venasque in France.

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We might not know what they meant,[br]but the people of the time certainly did.

0:08:21.760,0:08:27.816
The repetition of the same signs,[br]for so long, and at so many sites

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tells us that the artists[br]were making intentional choices.

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If we're talking about geometric shapes,

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with specific, culturally recognized,[br]agreed-upon meanings,

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than we could very well be looking

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at one of the oldest systems[br]of graphic communication in the world.

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I'm not talking about writing yet.

0:08:47.120,0:08:49.456
There's just not enough[br]characters at this point

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to have represented all of the words[br]in the spoken language,

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something which is a requirement[br]for a full writing system.

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Nor do we see the signs[br]repeating regularly enough

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to suggest that they were[br]some sort of alphabet.

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But what we do have[br]are some intriguing one-offs,

0:09:03.120,0:09:07.696
like this panel from La Pasiega in Spain,[br]known as "The Inscription,"

0:09:07.720,0:09:10.256
with its symmetrical markings on the left,

0:09:10.280,0:09:13.496
possible stylized representations[br]of hands in the middle,

0:09:13.520,0:09:15.840
and what looks a bit[br]like a bracket on the right.

0:09:17.080,0:09:19.936
The oldest systems of graphic[br]communication in the world --

0:09:19.960,0:09:24.896
Sumerian cuneiform, Egyptian hieroglyphs,[br]the earliest Chinese script,

0:09:24.920,0:09:28.496
all emerged between 4,000[br]and 5,000 years ago,

0:09:28.520,0:09:31.656
with each coming into existence[br]from an earlier protosystem

0:09:31.680,0:09:35.216
made up of counting marks[br]and pictographic representations,

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where the meaning[br]and the image were the same.

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

0:09:41.880,0:09:46.616
It's only later that we start to see[br]these pictographs become more stylized,

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until they almost become unrecognizable

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and that we also start to see[br]more symbols being invented

0:09:52.040,0:09:54.936
to represent all those other[br]missing words in language --

0:09:54.960,0:09:57.080
things like pronouns, adverbs, adjectives.

0:09:58.160,0:09:59.696
So knowing all this,

0:09:59.720,0:10:03.576
it seems highly unlikely that[br]the geometric signs from Ice Age Europe

0:10:03.600,0:10:06.296
were truly abstract written characters.

0:10:06.320,0:10:08.536
Instead, what's much more likely

0:10:08.560,0:10:12.536
is that these early artists[br]were also making counting marks,

0:10:12.560,0:10:16.576
maybe like this row of lines[br]from Riparo di Za Minic in Sicily,

0:10:16.600,0:10:19.216
as well as creating[br]stylized representations

0:10:19.240,0:10:21.736
of things from the world around them.

0:10:21.760,0:10:24.376
Could some of the signs[br]be weaponry or housing?

0:10:24.400,0:10:28.536
Or what about celestial objects[br]like star constellations?

0:10:28.560,0:10:33.176
Or maybe even rivers, mountains,[br]trees -- landscape features,

0:10:33.200,0:10:37.576
possibly like this black penniform[br]surrounded by strange bell-shaped signs

0:10:37.600,0:10:40.176
from the site of El Castillo in Spain.

0:10:40.200,0:10:43.496
The term penniform[br]means "feather-shaped" in Latin,

0:10:43.520,0:10:47.360
but could this actually be[br]a depiction of a plant or a tree?

0:10:47.720,0:10:50.696
Some researchers have begun[br]to ask these questions

0:10:50.720,0:10:53.616
about certain signs at specific sites,

0:10:53.640,0:10:58.536
but I believe the time has come[br]to revisit this category as a whole.

0:10:58.560,0:11:00.296
The irony in all of this, of course,

0:11:00.320,0:11:04.616
is that having just carefully classified[br]all of the signs into a single category,

0:11:04.640,0:11:08.136
I have a feeling that my next step[br]will involve breaking it back apart

0:11:08.160,0:11:12.416
as different types of imagery[br]are identified and separated off.

0:11:12.440,0:11:13.656
Now don't get me wrong,

0:11:13.680,0:11:16.296
the later creation[br]of fully developed writing

0:11:16.320,0:11:18.936
was an impressive feat in its own right.

0:11:18.960,0:11:20.416
But it's important to remember

0:11:20.440,0:11:23.736
that those early writing systems[br]didn't come out of a vacuum.

0:11:23.760,0:11:25.736
And that even 5,000 years ago,

0:11:25.760,0:11:29.096
people were already building[br]on something much older,

0:11:29.120,0:11:32.856
with its origins stretching back[br]tens of thousands of years --

0:11:32.880,0:11:36.976
to the geometric signs[br]of Ice Age Europe and far beyond,

0:11:37.000,0:11:40.296
to that point, deep[br]in our collective history,

0:11:40.320,0:11:44.376
when someone first came up with the idea[br]of making a graphic mark,

0:11:44.400,0:11:47.336
and forever changed the nature[br]of how we communicate.

0:11:47.360,0:11:48.576
Thank you.

0:11:48.600,0:11:52.040
(Applause)