9:59:59.000,9:59:59.000 There's something about caves. 9:59:59.000,9:59:59.000 A shadowy opening in a limestone cliff[br]that draws you in. 9:59:59.000,9:59:59.000 As you pass through the portal[br]between light and dark, 9:59:59.000,9:59:59.000 you enter a subterranean world. 9:59:59.000,9:59:59.000 A place of perpetual gloom, 9:59:59.000,9:59:59.000 a place of earthy smells,[br]of hushed silence. 9:59:59.000,9:59:59.000 Long ago in Europe, 9:59:59.000,9:59:59.000 ancient people also entered[br]these underground worlds. 9:59:59.000,9:59:59.000 As witness to their passage, 9:59:59.000,9:59:59.000 they left behind mysterious[br]engravings and paintings. 9:59:59.000,9:59:59.000 Like this panel of humans, triangles[br]and zig-zags from Ojo Guareña in Spain. 9:59:59.000,9:59:59.000 You now walk the same path[br]as these early artists. 9:59:59.000,9:59:59.000 And in this surreal, other-worldly place, 9:59:59.000,9:59:59.000 it's almost possible to imagine 9:59:59.000,9:59:59.000 that you hear the muffled foot-fall[br]of skin boots on soft earth, 9:59:59.000,9:59:59.000 or you see flickering of a torch[br]around the next bend. 9:59:59.000,9:59:59.000 When I'm in a cave, 9:59:59.000,9:59:59.000 I often find myself wondering,[br]what drove these people to go so deep? 9:59:59.000,9:59:59.000 to brave dangerous and narrow[br]passageways to leave their mark? 9:59:59.000,9:59:59.000 In this video clip, 9:59:59.000,9:59:59.000 that was shot half a kilometer,[br]or about a third of a mile underground, 9:59:59.000,9:59:59.000 in the cave of Curon in Spain, 9:59:59.000,9:59:59.000 we found a series[br]of red paintings on a ceiling 9:59:59.000,9:59:59.000 in a previously unexplored[br]section of the cave. 9:59:59.000,9:59:59.000 As we crawled forward, military-style,[br]with the ceiling getting ever-lower, 9:59:59.000,9:59:59.000 we finally got to a point[br]where the ceiling was so low, 9:59:59.000,9:59:59.000 that my husband and project[br]photographer, Dylan, 9:59:59.000,9:59:59.000 could no longer achieve focus[br]on the ceiling with his DSLR camera. 9:59:59.000,9:59:59.000 So while he filmed me, 9:59:59.000,9:59:59.000 I kept following the trail of red paint[br]with a single light, 9:59:59.000,9:59:59.000 and a point-and-shoot camera[br]that we kept for that type of occasion. 9:59:59.000,9:59:59.000 Half a kilometer underground. 9:59:59.000,9:59:59.000 Seriously. 9:59:59.000,9:59:59.000 What was somebody doing down there[br]with a torturous stone lamp? 9:59:59.000,9:59:59.000 (Laugher) 9:59:59.000,9:59:59.000 I mean --me, it makes sense, right? 9:59:59.000,9:59:59.000 But you know, 9:59:59.000,9:59:59.000 this is the kind of question that[br]I'm trying to answer with my research. 9:59:59.000,9:59:59.000 I study some of[br]the oldest art in the world. 9:59:59.000,9:59:59.000 It was created by these[br]early artists in Europe, 9:59:59.000,9:59:59.000 between 10 thousand[br]and 40 thousand years ago. 9:59:59.000,9:59:59.000 And the thing is, 9:59:59.000,9:59:59.000 is that I'm not just studying it[br]because it's beautiful, 9:59:59.000,9:59:59.000 though some of it certainly is. 9:59:59.000,9:59:59.000 But what I'm interested in[br]is the development of the modern mind, 9:59:59.000,9:59:59.000 of the evolution of creativity,[br]of imagination, of abstract thought. 9:59:59.000,9:59:59.000 About what it means to be human. 9:59:59.000,9:59:59.000 While all species communicate[br]in one way or another, 9:59:59.000,9:59:59.000 only we humans have really taken it[br]to another level. 9:59:59.000,9:59:59.000 Our desire and ability[br]to share and collaborate, 9:59:59.000,9:59:59.000 has been a huge part of out success story. 9:59:59.000,9:59:59.000 Our modern world is based on a global[br]network of information exchange. 9:59:59.000,9:59:59.000 Made possible, in large part,[br]by our ability to communicate. 9:59:59.000,9:59:59.000 In particular, using graphic[br]or written forms of communication. 9:59:59.000,9:59:59.000 The thing is though, 9:59:59.000,9:59:59.000 that we've been building[br]on the mental achievements 9:59:59.000,9:59:59.000 of those that came before us for so long, 9:59:59.000,9:59:59.000 that it's easy to forget that certain[br]abilities haven't already existed. 9:59:59.000,9:59:59.000 It's one of the things[br]I find most fascinating 9:59:59.000,9:59:59.000 about studying our deep history. 9:59:59.000,9:59:59.000 Those people didn't have the shoulders[br]of any giants to stand on, 9:59:59.000,9:59:59.000 they were the original shoulders. 9:59:59.000,9:59:59.000 And while a surprising number[br]of important inventions 9:59:59.000,9:59:59.000 come out of that distant time, 9:59:59.000,9:59:59.000 what I want to talk to you about today[br]is the invention of graphic communication. 9:59:59.000,9:59:59.000 There are three[br]main types of communication, 9:59:59.000,9:59:59.000 spoken, gestural -- [br]so things like sign language, 9:59:59.000,9:59:59.000 and graphic communication. 9:59:59.000,9:59:59.000 Spoken and gestural are,[br]by their very nature, ephemeral. 9:59:59.000,9:59:59.000 It requires close contact for a message[br]to be sent and received. 9:59:59.000,9:59:59.000 And after the moment of transmission,[br]it's gone forever. 9:59:59.000,9:59:59.000 Graphic communication, on the other hand,[br]decouples that relationship, 9:59:59.000,9:59:59.000 and with its invention, it became possible[br]for the first time, 9:59:59.000,9:59:59.000 for a message to be[br]transmitted and preserved, 9:59:59.000,9:59:59.000 beyond a single moment in place and time. 9:59:59.000,9:59:59.000 Europe is one of the first places 9:59:59.000,9:59:59.000 that we start to see graphic marks[br]regularly appearing 9:59:59.000,9:59:59.000 in caves, rock shelters, and even[br]a few surviving open air sites. 9:59:59.000,9:59:59.000 But this is not the Europe we know today. 9:59:59.000,9:59:59.000 This was a world dominated[br]by towering ice sheets 9:59:59.000,9:59:59.000 by towering ice sheets, three to four[br]kilometers high, 9:59:59.000,9:59:59.000 with sweeping grass plains[br]and frozen tundra. 9:59:59.000,9:59:59.000 This was the Ice Age. 9:59:59.000,9:59:59.000 Over the last century, 9:59:59.000,9:59:59.000 more than 350 Ice Age rock art sites[br]have been found across the continent. 9:59:59.000,9:59:59.000 Decorated with animals, abstract shapes,[br]and even the occasion human. 9:59:59.000,9:59:59.000 Like these engraved figures[br]from Grotta dell'Addaura in Sicily.