WEBVTT 00:00:00.000 --> 00:00:09.000 Jambo, bonjour, zdravstvujtye, dayo: these are a few of the languages 00:00:09.000 --> 00:00:13.000 that I've spoken little bits of over the course of the last six weeks, 00:00:13.000 --> 00:00:18.000 as I've been to 17 countries I think I'm up to, on this crazy tour I've been doing, 00:00:18.000 --> 00:00:21.000 checking out various aspects of the project that we're doing. 00:00:21.000 --> 00:00:23.000 And I'm going to tell you a little bit about later on. 00:00:23.000 --> 00:00:26.000 And visiting some pretty incredible places, 00:00:26.000 --> 00:00:32.000 places like Mongolia, Cambodia, New Guinea, South Africa, Tanzania twice -- 00:00:32.000 --> 00:00:34.000 I was here a month ago. NOTE Paragraph 00:00:34.000 --> 00:00:39.000 And the opportunity to make a whirlwind tour of the world like that 00:00:39.000 --> 00:00:42.000 is utterly amazing, for lots of reasons. 00:00:42.000 --> 00:00:44.000 You see some incredible stuff. 00:00:44.000 --> 00:00:46.000 And you get to make these spot comparisons 00:00:46.000 --> 00:00:48.000 between people all around the globe. 00:00:48.000 --> 00:00:50.000 And the thing that you really take away from that, 00:00:50.000 --> 00:00:53.000 the kind of surface thing that you take away from it, 00:00:53.000 --> 00:00:57.000 is not that we're all one, although I'm going to tell you about that, 00:00:57.000 --> 00:00:59.000 but rather how different we are. 00:00:59.000 --> 00:01:02.000 There is so much diversity around the globe. 00:01:02.000 --> 00:01:05.000 6,000 different languages spoken by six and a half billion people, 00:01:05.000 --> 00:01:08.000 all different colors, shapes, sizes. 00:01:08.000 --> 00:01:11.000 You walk down the street in any big city, you travel like that, 00:01:11.000 --> 00:01:15.000 and you are amazed at the diversity in the human species. NOTE Paragraph 00:01:15.000 --> 00:01:18.000 How do we explain that diversity? 00:01:18.000 --> 00:01:20.000 Well, that's what I'm going to talk about today, 00:01:20.000 --> 00:01:22.000 is how we're using the tools of genetics, 00:01:22.000 --> 00:01:28.000 population genetics in particular, to tell us how we generated this diversity, 00:01:28.000 --> 00:01:30.000 and how long it took. 00:01:30.000 --> 00:01:32.000 Now, the problem of human diversity, 00:01:32.000 --> 00:01:34.000 like all big scientific questions -- 00:01:34.000 --> 00:01:36.000 how do you explain something like that -- 00:01:36.000 --> 00:01:38.000 can be broken down into sub-questions. 00:01:38.000 --> 00:01:41.000 And you can ferret away at those little sub-questions. NOTE Paragraph 00:01:41.000 --> 00:01:43.000 First one is really a question of origins. 00:01:43.000 --> 00:01:45.000 Do we all share a common origin, in fact? 00:01:45.000 --> 00:01:48.000 And given that we do -- and that's the assumption 00:01:48.000 --> 00:01:51.000 everybody, I think, in this room would make -- when was that? 00:01:51.000 --> 00:01:53.000 When did we originate as a species? 00:01:53.000 --> 00:01:55.000 How long have we been divergent from each other? NOTE Paragraph 00:01:55.000 --> 00:01:59.000 And the second question is related, but slightly different. 00:01:59.000 --> 00:02:01.000 If we do spring from a common source, 00:02:01.000 --> 00:02:03.000 how did we come to occupy every corner of the globe, 00:02:03.000 --> 00:02:05.000 and in the process generate all of this diversity, 00:02:05.000 --> 00:02:08.000 the different ways of life, the different appearances, 00:02:08.000 --> 00:02:10.000 the different languages around the world? NOTE Paragraph 00:02:10.000 --> 00:02:13.000 Well, the question of origins, as with so many other questions in biology, 00:02:13.000 --> 00:02:15.000 seems to have been answered by Darwin over a century ago. 00:02:15.000 --> 00:02:17.000 In "The Descent of Man," he wrote, 00:02:17.000 --> 00:02:19.000 "In each great region of the world, the living mammals 00:02:19.000 --> 00:02:22.000 are closely related to the extinct species of the same region. 00:02:22.000 --> 00:02:25.000 It's therefore probable that Africa was formerly inhabited by extinct apes 00:02:25.000 --> 00:02:28.000 closely allied to the gorilla and chimpanzee, 00:02:28.000 --> 00:02:31.000 and as these two species are now man's nearest allies, 00:02:31.000 --> 00:02:33.000 it's somewhat more probable that our early progenitors 00:02:33.000 --> 00:02:35.000 lived on the African continent than elsewhere." NOTE Paragraph 00:02:35.000 --> 00:02:39.000 So we're done, we can go home -- finished the origin question. 00:02:39.000 --> 00:02:43.000 Well, not quite. Because Darwin was talking about our distant ancestry, 00:02:43.000 --> 00:02:45.000 our common ancestry with apes. 00:02:45.000 --> 00:02:49.000 And it is quite clear that apes originated on the African continent. 00:02:49.000 --> 00:02:52.000 Around 23 million years ago, they appear in the fossil record. 00:02:52.000 --> 00:02:55.000 Africa was actually disconnected from the other landmasses at that time, 00:02:55.000 --> 00:02:59.000 due to the vagaries of plate tectonics, floating around the Indian Ocean. 00:02:59.000 --> 00:03:01.000 Bumped into Eurasia around 16 million years ago, 00:03:01.000 --> 00:03:04.000 and then we had the first African exodus, as we call it. 00:03:04.000 --> 00:03:06.000 The apes that left at that time ended up in Southeast Asia, 00:03:06.000 --> 00:03:08.000 became the gibbons and the orangutans. 00:03:08.000 --> 00:03:10.000 And the ones that stayed on in Africa 00:03:10.000 --> 00:03:12.000 evolved into the gorillas, the chimpanzees and us. 00:03:12.000 --> 00:03:15.000 So, yes, if you're talking about our common ancestry with apes, 00:03:15.000 --> 00:03:19.000 it's very clear, by looking at the fossil record, we started off here. NOTE Paragraph 00:03:19.000 --> 00:03:21.000 But that's not really the question I'm asking. 00:03:21.000 --> 00:03:23.000 I'm asking about our human ancestry, 00:03:23.000 --> 00:03:26.000 things that we would recognize as being like us 00:03:26.000 --> 00:03:28.000 if they were sitting here in the room. 00:03:28.000 --> 00:03:30.000 If they were peering over your shoulder, 00:03:30.000 --> 00:03:33.000 you wouldn't leap back, like that. What about our human ancestry? 00:03:33.000 --> 00:03:35.000 Because if we go far enough back, 00:03:35.000 --> 00:03:38.000 we share a common ancestry with every living thing on Earth. 00:03:38.000 --> 00:03:41.000 DNA ties us all together, so we share ancestry with barracuda 00:03:41.000 --> 00:03:46.000 and bacteria and mushrooms, if you go far enough back -- over a billion years. 00:03:46.000 --> 00:03:48.000 What we're asking about though is human ancestry. 00:03:48.000 --> 00:03:50.000 How do we study that? NOTE Paragraph 00:03:50.000 --> 00:03:54.000 Well, historically, it has been studied using the science of paleoanthropology. 00:03:54.000 --> 00:03:56.000 Digging things up out of the ground, 00:03:56.000 --> 00:03:58.000 and largely on the basis of morphology -- 00:03:58.000 --> 00:04:01.000 the way things are shaped, often skull shape -- saying, 00:04:01.000 --> 00:04:05.000 "This looks a little bit more like us than that, so this must be my ancestor. 00:04:05.000 --> 00:04:08.000 This must be who I'm directly descended from." NOTE Paragraph 00:04:08.000 --> 00:04:11.000 The field of paleoanthropology, I'll argue, 00:04:11.000 --> 00:04:14.000 gives us lots of fascinating possibilities about our ancestry, 00:04:14.000 --> 00:04:17.000 but it doesn't give us the probabilities that we really want as scientists. 00:04:17.000 --> 00:04:19.000 What do I mean by that? 00:04:19.000 --> 00:04:21.000 You're looking at a great example here. 00:04:21.000 --> 00:04:23.000 These are three extinct species of hominids, 00:04:23.000 --> 00:04:25.000 potential human ancestors. 00:04:25.000 --> 00:04:28.000 All dug up just west of here in Olduvai Gorge, by the Leakey family. 00:04:28.000 --> 00:04:30.000 And they're all dating to roughly the same time. 00:04:30.000 --> 00:04:32.000 From left to right, we've got Homo erectus, Homo habilis, 00:04:32.000 --> 00:04:35.000 and Australopithecus -- now called Paranthropus boisei, 00:04:35.000 --> 00:04:40.000 the robust australopithecine. Three extinct species, same place, same time. 00:04:40.000 --> 00:04:43.000 That means that not all three could be my direct ancestor. 00:04:43.000 --> 00:04:46.000 Which one of these guys am I actually related to? 00:04:46.000 --> 00:04:51.000 Possibilities about our ancestry, but not the probabilities that we're really looking for. NOTE Paragraph 00:04:52.000 --> 00:04:56.000 Well, a different approach has been to look at morphology in humans 00:04:56.000 --> 00:04:59.000 using the only data that people really had at hand until quite recently -- 00:04:59.000 --> 00:05:01.000 again, largely skull shape. 00:05:01.000 --> 00:05:05.000 The first person to do this systematically was Linnaeus, 00:05:05.000 --> 00:05:07.000 Carl von Linne, a Swedish botanist, 00:05:07.000 --> 00:05:09.000 who in the eighteenth century took it upon himself 00:05:09.000 --> 00:05:11.000 to categorize every living organism on the planet. 00:05:11.000 --> 00:05:13.000 You think you've got a tough job? 00:05:13.000 --> 00:05:15.000 And he did a pretty good job. 00:05:15.000 --> 00:05:19.000 He categorized about 12,000 species in "Systema Naturae." 00:05:19.000 --> 00:05:22.000 He actually coined the term Homo sapiens -- it means wise man in Latin. 00:05:22.000 --> 00:05:26.000 But looking around the world at the diversity of humans, he said, 00:05:26.000 --> 00:05:30.000 "Well, you know, we seem to come in discreet sub-species or categories." 00:05:30.000 --> 00:05:34.000 And he talked about Africans and Americans and Asians and Europeans, 00:05:34.000 --> 00:05:37.000 and a blatantly racist category he termed "Monstrosus," 00:05:37.000 --> 00:05:40.000 which basically included all the people he didn't like, 00:05:40.000 --> 00:05:43.000 including imaginary folk like elves. NOTE Paragraph 00:05:44.000 --> 00:05:49.000 It's easy to dismiss this as the perhaps well-intentioned 00:05:49.000 --> 00:05:52.000 but ultimately benighted musings of an eighteenth century scientist 00:05:52.000 --> 00:05:54.000 working in the pre-Darwinian era. 00:05:54.000 --> 00:05:56.000 Except, if you had taken physical anthropology 00:05:56.000 --> 00:06:00.000 as recently as 20 or 30 years ago, in many cases you would have learned 00:06:00.000 --> 00:06:02.000 basically that same classification of humanity. 00:06:02.000 --> 00:06:07.000 Human races that according to physical anthropologists of 30, 40 years ago -- 00:06:07.000 --> 00:06:09.000 Carlton Coon is the best example -- 00:06:09.000 --> 00:06:13.000 had been diverging from each other -- this was in the post-Darwinian era -- 00:06:13.000 --> 00:06:16.000 for over a million years, since the time of Homo erectus. 00:06:16.000 --> 00:06:18.000 But based on what data? 00:06:18.000 --> 00:06:22.000 Very little. Very little. Morphology and a lot of guesswork. NOTE Paragraph 00:06:22.000 --> 00:06:24.000 Well, what I'm going to talk about today, 00:06:24.000 --> 00:06:27.000 what I'm going to talk about now is a new approach to this problem. 00:06:27.000 --> 00:06:30.000 Instead of going out and guessing about our ancestry, 00:06:30.000 --> 00:06:32.000 digging things up out of the ground, possible ancestors, 00:06:32.000 --> 00:06:34.000 and saying it on the basis of morphology -- 00:06:34.000 --> 00:06:36.000 which we still don't completely understand, 00:06:36.000 --> 00:06:40.000 we don't know the genetic causes underlying this morphological variation -- NOTE Paragraph 00:06:40.000 --> 00:06:42.000 what we need to do is turn the problem on its head. 00:06:42.000 --> 00:06:46.000 Because what we're really asking is a genealogical problem, 00:06:46.000 --> 00:06:48.000 or a genealogical question. 00:06:48.000 --> 00:06:53.000 What we're trying to do is construct a family tree for everybody alive today. 00:06:53.000 --> 00:06:55.000 And as any genealogist will tell you -- 00:06:55.000 --> 00:06:57.000 anybody have a member of the family, or maybe you 00:06:57.000 --> 00:07:00.000 have tried to construct a family tree, trace back in time? 00:07:00.000 --> 00:07:02.000 You start in the present, with relationships you're certain about. 00:07:02.000 --> 00:07:04.000 You and your siblings, you have a parent in common. 00:07:04.000 --> 00:07:06.000 You and your cousins share a grandparent in common. 00:07:06.000 --> 00:07:09.000 You gradually trace further and further back into the past, 00:07:09.000 --> 00:07:11.000 adding these ever more distant relationships. 00:07:11.000 --> 00:07:15.000 But eventually, no matter how good you are at digging up the church records, 00:07:15.000 --> 00:07:19.000 and all that stuff, you hit what the genealogists call a brick wall. 00:07:19.000 --> 00:07:22.000 A point beyond which you don't know anything else about your ancestors, 00:07:22.000 --> 00:07:26.000 and you enter this dark and mysterious realm we call history 00:07:26.000 --> 00:07:29.000 that we have to feel our way through with whispered guidance. NOTE Paragraph 00:07:29.000 --> 00:07:31.000 Who were these people who came before? 00:07:31.000 --> 00:07:34.000 We have no written record. Well, actually, we do. 00:07:34.000 --> 00:07:37.000 Written in our DNA, in our genetic code -- 00:07:37.000 --> 00:07:39.000 we have a historical document that takes us back in time 00:07:39.000 --> 00:07:43.000 to the very earliest days of our species. And that's what we study. NOTE Paragraph 00:07:43.000 --> 00:07:45.000 Now, a quick primer on DNA. 00:07:45.000 --> 00:07:48.000 I suspect that not everybody in the audience is a geneticist. 00:07:48.000 --> 00:07:52.000 It is a very long, linear molecule, a coded version 00:07:52.000 --> 00:07:55.000 of how to make another copy of you. It's your blueprint. 00:07:55.000 --> 00:07:58.000 It's composed of four subunits: A, C, G and T, we call them. 00:07:58.000 --> 00:08:02.000 And it's the sequence of those subunits that defines that blueprint. 00:08:02.000 --> 00:08:05.000 How long is it? Well, it's billions of these subunits in length. 00:08:05.000 --> 00:08:08.000 A haploid genome -- we actually have two copies of all of our chromosomes -- 00:08:08.000 --> 00:08:12.000 a haploid genome is around 3.2 billion nucleotides in length. 00:08:12.000 --> 00:08:14.000 And the whole thing, if you add it all together, 00:08:14.000 --> 00:08:16.000 is over six billion nucleotides long. 00:08:16.000 --> 00:08:19.000 If you take all the DNA out of one cell in your body, 00:08:19.000 --> 00:08:23.000 and stretch it end to end, it's around two meters long. 00:08:23.000 --> 00:08:25.000 If you take all the DNA out of every cell in your body, 00:08:25.000 --> 00:08:29.000 and you stretch it end to end, it would reach from here to the moon and back, 00:08:29.000 --> 00:08:32.000 thousands of times. It's a lot of information. NOTE Paragraph 00:08:32.000 --> 00:08:38.000 And so when you're copying this DNA molecule to pass it on, it's a pretty tough job. 00:08:38.000 --> 00:08:42.000 Imagine the longest book you can think of, "War and Peace." 00:08:42.000 --> 00:08:44.000 Now multiply it by 100. 00:08:44.000 --> 00:08:46.000 And imagine copying that by hand. 00:08:46.000 --> 00:08:48.000 And you're working away until late at night, 00:08:48.000 --> 00:08:50.000 and you're very, very careful, and you're drinking coffee 00:08:50.000 --> 00:08:52.000 and you're paying attention, but, occasionally, 00:08:52.000 --> 00:08:54.000 when you're copying this by hand, 00:08:54.000 --> 00:08:56.000 you're going to make a little typo, a spelling mistake -- 00:08:56.000 --> 00:09:00.000 substitute an I for an E, or a C for a T. NOTE Paragraph 00:09:00.000 --> 00:09:04.000 Same thing happens to our DNA as it's being passed on through the generations. 00:09:04.000 --> 00:09:07.000 It doesn't happen very often. We have a proofreading mechanism built in. 00:09:07.000 --> 00:09:09.000 But when it does happen, and these changes get transmitted down 00:09:09.000 --> 00:09:12.000 through the generations, they become markers of descent. 00:09:12.000 --> 00:09:14.000 If you share a marker with someone, 00:09:14.000 --> 00:09:17.000 it means you share an ancestor at some point in the past, 00:09:17.000 --> 00:09:19.000 the person who first had that change in their DNA. 00:09:19.000 --> 00:09:22.000 And it's by looking at the pattern of genetic variation, 00:09:22.000 --> 00:09:25.000 the pattern of these markers in people all over the world, 00:09:25.000 --> 00:09:29.000 and assessing the relative ages when they occurred throughout our history, 00:09:29.000 --> 00:09:32.000 that we've been able to construct a family tree for everybody alive today. NOTE Paragraph 00:09:32.000 --> 00:09:35.000 These are two pieces of DNA that we use quite widely in our work. 00:09:35.000 --> 00:09:38.000 Mitochondrial DNA, tracing a purely maternal line of descent. 00:09:38.000 --> 00:09:41.000 You get your mtDNA from your mother, and your mother's mother, 00:09:41.000 --> 00:09:43.000 all the way back to the very first woman. 00:09:43.000 --> 00:09:46.000 The Y chromosome, the piece of DNA that makes men men, 00:09:46.000 --> 00:09:49.000 traces a purely paternal line of descent. 00:09:49.000 --> 00:09:53.000 Everybody in this room, everybody in the world, 00:09:53.000 --> 00:09:57.000 falls into a lineage somewhere on these trees. 00:09:57.000 --> 00:10:00.000 Now, even though these are simplified versions of the real trees, 00:10:00.000 --> 00:10:02.000 they're still kind of complicated, so let's simplify them. 00:10:02.000 --> 00:10:04.000 Turn them on their sides, combine them so that they look like a tree 00:10:04.000 --> 00:10:07.000 with the root at the bottom and the branches going up. 00:10:07.000 --> 00:10:09.000 What's the take-home message? NOTE Paragraph 00:10:09.000 --> 00:10:11.000 Well, the thing that jumps out at you first 00:10:11.000 --> 00:10:14.000 is that the deepest lineages in our family trees 00:10:14.000 --> 00:10:19.000 are found within Africa, among Africans. 00:10:19.000 --> 00:10:22.000 That means that Africans have been accumulating 00:10:22.000 --> 00:10:25.000 this mutational diversity for longer. 00:10:25.000 --> 00:10:29.000 And what that means is that we originated in Africa. It's written in our DNA. 00:10:29.000 --> 00:10:34.000 Every piece of DNA we look at has greater diversity within Africa than outside of Africa. 00:10:34.000 --> 00:10:37.000 And at some point in the past, a sub-group of Africans 00:10:37.000 --> 00:10:41.000 left the African continent to go out and populate the rest of the world. NOTE Paragraph 00:10:41.000 --> 00:10:43.000 Now, how recently do we share this ancestry? 00:10:43.000 --> 00:10:47.000 Was it millions of years ago, which we might suspect 00:10:47.000 --> 00:10:50.000 by looking at all this incredible variation around the world? 00:10:50.000 --> 00:10:53.000 No, the DNA tells a story that's very clear. 00:10:53.000 --> 00:10:58.000 Within the last 200,000 years, we all share an ancestor, a single person -- 00:10:58.000 --> 00:11:02.000 Mitochondrial Eve, you might have heard about her -- in Africa, 00:11:02.000 --> 00:11:05.000 an African woman who gave rise to all the mitochondrial diversity in the world today. NOTE Paragraph 00:11:05.000 --> 00:11:07.000 But what's even more amazing 00:11:07.000 --> 00:11:09.000 is that if you look at the Y-chromosome side, 00:11:09.000 --> 00:11:13.000 the male side of the story, the Y-chromosome Adam 00:11:13.000 --> 00:11:15.000 only lived around 60,000 years ago. 00:11:15.000 --> 00:11:18.000 That's only about 2,000 human generations, 00:11:18.000 --> 00:11:21.000 the blink of an eye in an evolutionary sense. 00:11:22.000 --> 00:11:25.000 That tells us we were all still living in Africa at that time. 00:11:25.000 --> 00:11:27.000 This was an African man who gave rise 00:11:27.000 --> 00:11:29.000 to all the Y chromosome diversity around the world. 00:11:29.000 --> 00:11:31.000 It's only within the last 60,000 years 00:11:31.000 --> 00:11:35.000 that we have started to generate this incredible diversity we see around the world. 00:11:35.000 --> 00:11:37.000 Such an amazing story. 00:11:37.000 --> 00:11:40.000 We're all effectively part of an extended African family. NOTE Paragraph 00:11:41.000 --> 00:11:44.000 Now, that seems so recent. Why didn't we start to leave earlier? 00:11:44.000 --> 00:11:48.000 Why didn't Homo erectus evolve into separate species, 00:11:48.000 --> 00:11:50.000 or sub-species rather, human races around the world? 00:11:50.000 --> 00:11:54.000 Why was it that we seem to have come out of Africa so recently? 00:11:54.000 --> 00:11:56.000 Well, that's a big question. These "why" questions, 00:11:56.000 --> 00:12:01.000 particularly in genetics and the study of history in general, are always the big ones, 00:12:01.000 --> 00:12:03.000 the ones that are tough to answer. NOTE Paragraph 00:12:03.000 --> 00:12:06.000 And so when all else fails, talk about the weather. 00:12:06.000 --> 00:12:09.000 What was going on to the world's weather around 60,000 years ago? 00:12:09.000 --> 00:12:12.000 Well, we were going into the worst part of the last ice age. 00:12:12.000 --> 00:12:15.000 The last ice age started roughly 120,000 years ago. 00:12:15.000 --> 00:12:19.000 It went up and down, and it really started to accelerate around 70,000 years ago. 00:12:19.000 --> 00:12:21.000 Lots of evidence from sediment cores 00:12:21.000 --> 00:12:24.000 and the pollen types, oxygen isotopes and so on. 00:12:24.000 --> 00:12:27.000 We hit the last glacial maximum around 16,000 years ago, 00:12:27.000 --> 00:12:31.000 but basically, from 70,000 years on, things were getting really tough, 00:12:31.000 --> 00:12:36.000 getting very cold. The Northern Hemisphere had massive growing ice sheets. 00:12:36.000 --> 00:12:40.000 New York City, Chicago, Seattle, all under a sheet of ice. 00:12:40.000 --> 00:12:45.000 Most of Britain, all of Scandinavia, covered by ice several kilometers thick. NOTE Paragraph 00:12:45.000 --> 00:12:48.000 Now, Africa is the most tropical continent on the planet -- 00:12:48.000 --> 00:12:52.000 about 85 percent of it lies between Cancer and Capricorn -- 00:12:52.000 --> 00:12:54.000 and there aren't a lot of glaciers here, 00:12:54.000 --> 00:12:56.000 except on the high mountains here in East Africa. 00:12:56.000 --> 00:12:59.000 So what was going on here? We weren't covered in ice in Africa. 00:12:59.000 --> 00:13:02.000 Rather, Africa was drying out at that time. 00:13:02.000 --> 00:13:04.000 This is a paleo-climatological map 00:13:04.000 --> 00:13:07.000 of what Africa looked like between 60,000 and 70,000 years ago, 00:13:07.000 --> 00:13:11.000 reconstructed from all these pieces of evidence that I mentioned before. 00:13:11.000 --> 00:13:15.000 The reason for that is that ice actually sucks moisture out of the atmosphere. 00:13:15.000 --> 00:13:19.000 If you think about Antarctica, it's technically a desert, it gets so little precipitation. NOTE Paragraph 00:13:19.000 --> 00:13:21.000 So the whole world was drying out. 00:13:21.000 --> 00:13:25.000 The sea levels were dropping. And Africa was turning to desert. 00:13:25.000 --> 00:13:28.000 The Sahara was much bigger then than it is now. 00:13:28.000 --> 00:13:31.000 And the human habitat was reduced to just a few small pockets, 00:13:31.000 --> 00:13:33.000 compared to what we have today. 00:13:33.000 --> 00:13:35.000 The evidence from genetic data 00:13:35.000 --> 00:13:38.000 is that the human population around this time, roughly 70,000 years ago, 00:13:38.000 --> 00:13:41.000 crashed to fewer than 2,000 individuals. 00:13:41.000 --> 00:13:45.000 We nearly went extinct. We were hanging on by our fingernails. NOTE Paragraph 00:13:45.000 --> 00:13:48.000 And then something happened. A great illustration of it. 00:13:48.000 --> 00:13:50.000 Look at some stone tools. 00:13:50.000 --> 00:13:54.000 The ones on the left are from Africa, from around a million years ago. 00:13:54.000 --> 00:13:57.000 The ones on the right were made by Neanderthals, our distant cousins, 00:13:57.000 --> 00:13:59.000 not our direct ancestors, living in Europe, 00:13:59.000 --> 00:14:03.000 and they date from around 50,000 or 60,000 years ago. 00:14:03.000 --> 00:14:06.000 Now, at the risk of offending any paleoanthropologists 00:14:06.000 --> 00:14:09.000 or physical anthropologists in the audience, 00:14:09.000 --> 00:14:14.000 basically there's not a lot of change between these two stone tool groups. 00:14:14.000 --> 00:14:17.000 The ones on the left are pretty similar to the ones on the right. 00:14:17.000 --> 00:14:21.000 We are in a period of long cultural stasis from a million years ago 00:14:21.000 --> 00:14:23.000 until around 60,000 to 70,000 years ago. 00:14:23.000 --> 00:14:25.000 The tool styles don't change that much. 00:14:25.000 --> 00:14:27.000 The evidence is that the human way of life 00:14:27.000 --> 00:14:29.000 didn't change that much during that period. NOTE Paragraph 00:14:29.000 --> 00:14:34.000 But then 50, 60, 70 thousand years ago, somewhere in that region, 00:14:34.000 --> 00:14:37.000 all hell breaks loose. Art makes its appearance. 00:14:37.000 --> 00:14:40.000 The stone tools become much more finely crafted. 00:14:40.000 --> 00:14:42.000 The evidence is that humans begin to specialize in particular prey species, 00:14:43.000 --> 00:14:45.000 at particular times of the year. 00:14:45.000 --> 00:14:48.000 The population size started to expand. 00:14:48.000 --> 00:14:50.000 Probably, according to what many linguists believe, 00:14:50.000 --> 00:14:54.000 fully modern language, syntactic language -- subject, verb, object -- 00:14:54.000 --> 00:14:58.000 that we use to convey complex ideas, like I'm doing now, appeared around that time. 00:14:58.000 --> 00:15:02.000 We became much more social. The social networks expanded. NOTE Paragraph 00:15:02.000 --> 00:15:07.000 This change in behavior allowed us to survive these worsening conditions in Africa, 00:15:07.000 --> 00:15:11.000 and they allowed us to start to expand around the world. 00:15:12.000 --> 00:15:15.000 We've been talking at this conference about African success stories. 00:15:15.000 --> 00:15:18.000 Well, you want the ultimate African success story? 00:15:18.000 --> 00:15:21.000 Look in the mirror. You're it. The reason you're alive today 00:15:21.000 --> 00:15:25.000 is because of those changes in our brains that took place in Africa -- 00:15:25.000 --> 00:15:28.000 probably somewhere in the region where we're sitting right now, 00:15:28.000 --> 00:15:31.000 around 60, 70 thousand years ago -- 00:15:31.000 --> 00:15:34.000 allowing us not only to survive in Africa, but to expand out of Africa. 00:15:34.000 --> 00:15:37.000 An early coastal migration along the south coast of Asia, 00:15:37.000 --> 00:15:39.000 leaving Africa around 60,000 years ago, 00:15:39.000 --> 00:15:43.000 reaching Australia very rapidly, by 50,000 years ago. 00:15:43.000 --> 00:15:45.000 A slightly later migration up into the Middle East. 00:15:45.000 --> 00:15:47.000 These would have been savannah hunters. NOTE Paragraph 00:15:47.000 --> 00:15:49.000 So those of you who are going on one of the post-conference tours, 00:15:49.000 --> 00:15:51.000 you'll get to see what a real savannah is like. 00:15:51.000 --> 00:15:53.000 And it's basically a meat locker. 00:15:53.000 --> 00:15:56.000 People who would have specialized in killing the animals, 00:15:56.000 --> 00:15:59.000 hunting the animals on those meat locker savannahs, moving up, 00:15:59.000 --> 00:16:03.000 following the grasslands into the Middle East around 45,000 years ago, 00:16:03.000 --> 00:16:05.000 during one of the rare wet phases in the Sahara. 00:16:05.000 --> 00:16:08.000 Migrating eastward, following the grasslands, 00:16:08.000 --> 00:16:10.000 because that's what they were adapted to live on. NOTE Paragraph 00:16:10.000 --> 00:16:12.000 And when they reached Central Asia, 00:16:12.000 --> 00:16:15.000 they reached what was effectively a steppe super-highway, 00:16:15.000 --> 00:16:17.000 a grassland super-highway. 00:16:17.000 --> 00:16:19.000 The grasslands at that time -- this was during the last ice age -- 00:16:19.000 --> 00:16:22.000 stretched basically from Germany all the way over to Korea, 00:16:22.000 --> 00:16:24.000 and the entire continent was open to them. 00:16:24.000 --> 00:16:26.000 Entering Europe around 35,000 years ago, 00:16:26.000 --> 00:16:28.000 and finally, a small group migrating up 00:16:28.000 --> 00:16:32.000 through the worst weather imaginable, Siberia, 00:16:32.000 --> 00:16:34.000 inside the Arctic Circle, during the last ice age -- 00:16:34.000 --> 00:16:38.000 temperature was at -70, -80, even -100, perhaps -- 00:16:38.000 --> 00:16:42.000 migrating into the Americas, ultimately reaching that final frontier. NOTE Paragraph 00:16:42.000 --> 00:16:46.000 An amazing story, and it happened first in Africa. 00:16:46.000 --> 00:16:48.000 The changes that allowed us to do that, 00:16:48.000 --> 00:16:51.000 the evolution of this highly adaptable brain that we all carry around with us, 00:16:51.000 --> 00:16:53.000 allowing us to create novel cultures, 00:16:53.000 --> 00:16:56.000 allowing us to develop the diversity 00:16:56.000 --> 00:16:59.000 that we see on a whirlwind trip like the one I've just been on. NOTE Paragraph 00:17:00.000 --> 00:17:04.000 Now, that story I just told you is literally a whirlwind tour 00:17:04.000 --> 00:17:09.000 of how we populated the world, the great Paleolithic wanderings of our species. 00:17:09.000 --> 00:17:11.000 And that's the story that I told a couple of years ago 00:17:11.000 --> 00:17:15.000 in my book, "The Journey of Man," and a film that we made with the same title. 00:17:15.000 --> 00:17:18.000 And as we were finishing up that film -- 00:17:18.000 --> 00:17:20.000 it was co-produced with National Geographic -- 00:17:20.000 --> 00:17:23.000 I started talking to the folks at NG about this work. 00:17:23.000 --> 00:17:27.000 And they got really excited about it. They liked the film, but they said, 00:17:27.000 --> 00:17:29.000 "You know, we really see this as kind of 00:17:29.000 --> 00:17:33.000 the next wave in the study of human origins, where we all came from, 00:17:33.000 --> 00:17:38.000 using the tools of DNA to map the migrations around the world. 00:17:38.000 --> 00:17:40.000 You know, the study of human origins is kind of in our DNA, 00:17:40.000 --> 00:17:42.000 and we want to take it to the next level. 00:17:42.000 --> 00:17:44.000 What do you want to do next?" 00:17:44.000 --> 00:17:46.000 Which is a great question to be asked by National Geographic. NOTE Paragraph 00:17:46.000 --> 00:17:50.000 And I said, "Well, you know, what I've sketched out here is just that. 00:17:50.000 --> 00:17:54.000 It is a very coarse sketch of how we migrated around the planet. 00:17:54.000 --> 00:17:57.000 And it's based on a few thousand people we've sampled from, 00:17:57.000 --> 00:17:59.000 you know, a handful of populations around the world. 00:17:59.000 --> 00:18:03.000 Studied a few genetic markers, and there are lots of gaps on this map. 00:18:03.000 --> 00:18:05.000 We've just connected the dots. What we need to do 00:18:05.000 --> 00:18:09.000 is increase our sample size by an order of magnitude or more -- 00:18:09.000 --> 00:18:13.000 hundreds of thousands of DNA samples from people all over the world." NOTE Paragraph 00:18:13.000 --> 00:18:16.000 And that was the genesis of the Genographic Project. 00:18:16.000 --> 00:18:19.000 The project launched in April 2005. 00:18:19.000 --> 00:18:23.000 It has three core components. Obviously, science is a big part of it. 00:18:23.000 --> 00:18:26.000 The field research that we're doing around the world with indigenous peoples. 00:18:26.000 --> 00:18:29.000 People who have lived in the same location for a long period of time 00:18:29.000 --> 00:18:31.000 retain a connection to the place where they live 00:18:31.000 --> 00:18:33.000 that many of the rest of us have lost. 00:18:34.000 --> 00:18:36.000 So my ancestors come from all over northern Europe. 00:18:36.000 --> 00:18:39.000 I live in the Eastern Seaboard of North America when I'm not traveling. 00:18:39.000 --> 00:18:42.000 Where am I indigenous to? Nowhere really. My genes are all jumbled up. 00:18:42.000 --> 00:18:45.000 But there are people who retain that link to their ancestors 00:18:45.000 --> 00:18:48.000 that allows us to contextualize the DNA results. NOTE Paragraph 00:18:48.000 --> 00:18:50.000 That's the focus of the field research, 00:18:50.000 --> 00:18:52.000 the centers that we've set up all over the world -- 00:18:52.000 --> 00:18:55.000 10 of them, top population geneticists. 00:18:55.000 --> 00:18:58.000 But, in addition, we wanted to open up this study to anybody around the world. 00:18:58.000 --> 00:19:02.000 How often do you get to participate in a big scientific project? 00:19:02.000 --> 00:19:04.000 The Human Genome Project, or a Mars Rover mission. NOTE Paragraph 00:19:04.000 --> 00:19:06.000 In this case, you actually can. 00:19:06.000 --> 00:19:10.000 You can go onto our website, Nationalgeographic.com/genographic. 00:19:10.000 --> 00:19:13.000 You can order a kit. You can test your own DNA. 00:19:13.000 --> 00:19:16.000 And you can actually submit those results to the database, 00:19:16.000 --> 00:19:18.000 and tell us a little about your genealogical background, 00:19:18.000 --> 00:19:22.000 have the data analyzed as part of the scientific effort. NOTE Paragraph 00:19:22.000 --> 00:19:26.000 Now, this is all a nonprofit enterprise, and so the money that we raise, 00:19:26.000 --> 00:19:29.000 after we cover the cost of doing the testing and making the kit components, 00:19:29.000 --> 00:19:31.000 gets plowed back into the project. 00:19:31.000 --> 00:19:33.000 The majority going to something we call the Legacy Fund. 00:19:33.000 --> 00:19:37.000 It's a charitable entity, basically a grant-giving entity 00:19:37.000 --> 00:19:39.000 that gives money back to indigenous groups around the world 00:19:39.000 --> 00:19:43.000 for educational, cultural projects initiated by them. 00:19:43.000 --> 00:19:45.000 They apply to this fund in order to do various projects, 00:19:45.000 --> 00:19:47.000 and I'll show you a couple of examples. NOTE Paragraph 00:19:47.000 --> 00:19:50.000 So how are we doing on the project? We've got about 25,000 samples 00:19:50.000 --> 00:19:52.000 collected from indigenous people around the world. 00:19:52.000 --> 00:19:55.000 The most amazing thing has been the interest on the part of the public; 00:19:55.000 --> 00:19:58.000 210,000 people have ordered these participation kits 00:19:58.000 --> 00:20:00.000 since we launched two years ago, 00:20:00.000 --> 00:20:03.000 which has raised around five million dollars, 00:20:03.000 --> 00:20:06.000 the majority of which, at least half, is going back into the Legacy Fund. NOTE Paragraph 00:20:06.000 --> 00:20:10.000 We've just awarded the first Legacy Grants totaling around 500,000 dollars. 00:20:10.000 --> 00:20:13.000 Projects around the world -- documenting oral poetry in Sierra Leone, 00:20:13.000 --> 00:20:16.000 preserving traditional weaving patterns in Gaza, 00:20:16.000 --> 00:20:19.000 language revitalization in Tajikistan, etc., etc. 00:20:19.000 --> 00:20:22.000 So the project is going very, very well, 00:20:22.000 --> 00:20:26.000 and I urge you to check out the website and watch this space. NOTE Paragraph 00:20:26.000 --> 00:20:28.000 Thank you very much. 00:20:28.000 --> 00:20:30.000 (Applause)