"Beyond Earth's atmosphere, life is impossible." "Exposed to the vacuum of space, you'd be unconscious within 12 seconds..." "..and last little more than two minutes." "And yet, for more than a decade, we've made this harshest of environments our home." "Today, the journey off our planet begins here in the cosmonaut training facility on the outskirts of Moscow." "I am floating in a spacesuit above the International Space Station." "It's surely as close as I'm going to get to being in space." "Astronauts have to do this for hours at a time, six, seven, eight-hour spacewalks." "They're going to have to perform many of them to install this module when it's taken up into space." "Over there, that's the Zvezda Module - the Russian habitation module." "It's where the cosmonauts sleep, you know, where they eat, it's their lounge in space." "You can just imagine, can't you?" "You can imagine the Earth stretching out over there, curving away." "Ah-h!" "I think it would be wonderful." "So wonderful." "It's kind of one of those things you always dream of, you know." "I did anyway - doing a spacewalk... ..out in space on the Space Station." "Since 2nd November, 2000, when the first expedition arrived the International Space Station has been continuously occupied..." "..humanity's permanent outpost amongst the stars." "You know, for me, this defines what it means to be human - throughout the whole history of life on Earth, of all the creatures that have ever lived in the oceans and the land or in the sky," "only one has ever made it off its home world." "So why is it that we alone have ventured out into space?" "What is it that makes us special?" "As far as we know, we humans are unique in the universe..." "..the only creatures to have developed the ability to ask deep questions about the cosmos..." "..and ponder our place within it." "Perhaps the most fundamental question we've asked is how do we become who we are, a space-faring civilisation?" "What drove our ascent from ape to man..." "..and from the dawn of civilisation..." "..to the stars?" "It's a story that begins in Ethiopia, where our story began." "High in the mountains lives a creature that allows us to glimpse our origins." "Oh, oh, oh!" "You're not supposed to look baboons in the eye, so I'm going to just approach them carefully." "I think that was a sneeze rather than a warning cry." "These are gelada baboons - they're a species of Old World monkey found only here in the Ethiopian highlands." "And we and the other great apes share a common ancestor with them, around 25 to 30 million years ago, so, in evolutionary terms, we belong to the same group - the higher primates." "So I suppose if you want a simple answer to the question - who are we?" "It's one of them." "The geladas aren't true baboons." "They are, in fact, the last remaining species of a group of primates that was once one of the most successful in Africa." "Although they're not our closest cousins, by any means, they have the most complex social system of any non-human primates, they live in groups of up to 500." "They also have the most complex vocalisations of any non-human primate." "They have sounds for attack and defence, also reassurance, sounds for danger, also solicitation." "And they'll string them together into long sequences." "But for all the similarities with the other primates, there is clearly a huge gulf between them and us." "And whilst you see glimpses of human-like behaviour, there's nothing anywhere near as sophisticated as us." "And, er, gelada, for all their sophisticated vocalisations, have nothing that you could even remotely refer to as language." "So it's obvious that we have something extra." "Since we split from our common ancestor the geladas have retreated into the highlands." "But our intelligence and way of life have changed unrecognisably." "We've gone on to colonise every corner of the Earth..." "..and beyond." "Solomon Tesfay is one of the Oromo people of central Ethiopia." "They've been fishing the lake's rich waters since they arrived here in the 16th century." "Constructing complicated tools, like boats, nets and spaceships is a skill unique to the human mind." "And this ability is thought to have emerged for the very first time in the hills around the lake." "This area's known as Gademotta, it's a volcanic ridge pushed up from the floor of the Rift Valley to form an ancient caldera." "Over a quarter of a million years ago, this was home to a group of early humans, attracted here by the lake, but also by this stuff - obsidian." "Obsidian is volcanic glass formed spontaneously by rapidly cooling lava." "But some of the fragments that litter the ground here are far from natural." "Quite difficult, actually." "You don't want to be working it the whole day and not produce anything, so something like this will be an ideal striking platform." "Right, so you made that look easy." "Ah." "What am I looking to do now?" "So you first visualise what you want, you are looking for a spear out of this flake." "So you will need to work around the edge, thin this down because they're going to be the edges of the spear point." "Archaeologists have uncovered hundreds of obsidian spear points at Gademotta, some of which were made more than 250,000 years ago, the oldest of their kind ever found.'" "It's kind of easy to just randomly knock a piece off." "Yeah." "But then when you start actually crafting the shape..." "Yeah." "So it's hit the angle, here." "Oh, I see, there." "Oh, yeah." "Yes." "I can see that this takes..." "takes an intelligent animal to craft because it takes concentration and dedication." "Yes." "And you need to know exactly what you're doing." "Yes." "And you need to sit here and do it and have patience, and be able to visualise the shape." "Yes, definitely." "But fashioning the spear's point is just the first stage in constructing a weapon that would have flown through the air like a javelin.'" "This would have been attached to a wooden piece by some animal skin and it's thought some kind of glue." "So this whole weapon is a complex thing, you've got to imagine something that doesn't exist - a spear made out of all sorts of different materials." "It's an object that's too complicated for a single individual to conceive of and to build in a single lifetime." "An object like this requires lots of individuals working together and also passing information on from generation to generation, so, over time, better spears can be constructed." "That requires some means of communication, probably some kind of primitive language." "So this is the earliest physical evidence we've found of minds that think like ours." "What happened here wasn't just a pivotal moment in human evolution." "It was a turning point in a grander story." "For the vast majority of the age of the universe, the story of the atoms in this rock was the same as the story of the atoms in my body." "They were forged 13.8 billion years ago, moments after the Big Bang, the heavier ones were assembled in hearts of long-dead stars." "And 4.8 billion years ago, they collapsed under their own gravity to form the solar system - a glowing ball of gas and some bigger rocks." "And for all we know, despite all its majesty, that's all the night sky is - just a collection of glowing balls of gas and some rocks." "But then, around 250,000 years ago, a clump of atoms became aware - it looked to the rock and saw a spear." "In one of the universe's hundred billion galaxies..." "..orbiting one of that galaxy's 200 billion stars... ..on a small, seemingly insignificant, blue-green planet..." "..a tiny part of the cosmos had become conscious." "But how did hydrogen atoms forged at the beginning of time come to wake up?" "And how was it in only a quarter of a million years, that's a thousandth of 1% of the age of the universe, those atoms went from building weapons out of stone to constructing spacecraft?" "The trigger for our transformation from apeman to spaceman can be found not on Earth, but glimpsed in the night sky." "For centuries, the seafaring peoples of East Africa have relied on the ocean for their survival." "Sailors like Abdullah Ahmed Mohammed established trade routes across the Indian Ocean..." "..guided by the light of the stars." "Polaris, the north star, appears stationary in the night sky because it's the line directly on the axis about which the Earth revolves." "But despite its appearance, it's far from constant." "In 2,000 years, another star, Gamma Cephei, will sit over the Pole and Polaris will arc through the sky like the others." "Because the Earth isn't a perfect sphere, the gravitational pull of the moon and the sun causes the Earth's axis to wobble." "North is over there, the axis is pointing, by coincidence, toward the star that we call Polaris, the north star." "But in just a few thousand years, as the axis begins to move, the Earth's North Pole will point to a different place in the sky." "The Earth's axis is said to precess, tracing out a circle in the sky once every 27,000 years." "But precession doesn't just alter our view of the stars, it changes the point in the planet's orbit at which summer and winter occur." "And that affects the amount of sunlight that falls on the Earth in summer and winter, and that has an effect on the climate, it makes it vary." "But the solar system is way more complicated than that." "The Earth is subjected to many different gravitational pulls and tugs, not least from the planet Jupiter." "And that has the effect of changing the Earth's orbit itself." "Now, the most important change is over a time period of around 400,000 years, where the Earth's orbit, the ellipse itself, gets bigger and smaller and bigger and smaller." "Every 400,000 years, these variations in the Earth's orbit conspire to amplify the effects of precession." "And in one place on Earth, the planet's geography amplifies them still further, to produce periods of rapid and extreme climate fluctuation." "10 million years ago, this area was a flat plain covered in thick, dense forest, which made it the perfect place for our early, tree-dwelling ancestors." "But then, around that time, volcanic activity raised the land up, in places by over three kilometres, to form this - the Great Rift Valley." "During those times when the Earth's orbit was at its most elliptical, the Rift Valley would experience intense rainfall..." "..and deep lakes would appear dotted all over the landscape." "And then, within just a few thousand years, conditions would change." "It would become dry and arid and those lakes would disappear." "It's thought that it was this rapidly-changing environment that drove our transformation from ape to man." "And the reason we think that is because we found the evidence strewn across the valley floor..." "..beginning with our early ancestors, who settled in the newly-formed rift." "Three million years ago, the homonym species that could be found in East Africa was Australopithecus." "It's a kind of a grim-looking chap." "This is really not much more than a chimpanzee that stands upright, certainly in brain capacity." "Its brain volume is around 400cc." "But then, 1.8 million years ago, something spectacular happens." "You get an explosion of homonym species, including this... ..Homo erectus, with a brain size that is double Australopithecus." "Then, 800,000 years ago, this species appears," "Homo heidelbergensis, accompanied by another rapid increase in brain size, from 800cc to around 1,200cc." "Then, we wind forward to 200,000 years ago, this skull, called Omo II, with a brain size of around 1,400-1,500cc, which is close to my brain size." "So this is one of the first skulls that you can say is a modern human." "Interestingly, each one of these increases in brain size occurred at a time when the Earth's orbit was at its most elliptical..." "..and the climate at its most volatile." "So the theory is that human intelligence, our intelligence, is a response to periods of very rapid and violent climate change, specifically, here in the Rift Valley of East Africa." "And that ultimately, it was the precise geography of our corner of the universe that made us who we are." "You know, I find it quite dizzying, a very powerful thought, that my existence, the existence of my brain, the existence of us, our species, Homo sapiens, was a result of changes in the Earth's orbit," "which depend on the precise position and orbits of the other planets in the solar system, the way that the Earth's spin axis moves around, which depends on the position and mass of the moon and the position and mass of the sun" "and the influence of those changes on the climate here on Earth and, in particular, that there's a place, like this, that can amplify those changes in just such a way that it makes living things, my ancestors," "respond by increasing their brain size, increasing their intelligence." "It's these brains that separate us from the other primates." "They evolved in response to rapidly-fluctuating climate, and now they enable us to colonise every environment on the planet." "At the heart of the Danakil Depression, the volcanism that sculpted the Great Rift is still active..." "..creating some of the harshest conditions on Earth." "Yet, it's here that the Afar people have made their home." "To exist here, the Afar rely on all the advantages that large brains gave those very first humans..." "..the ability to club together in groups... ..develop tools and technologies to provide food and shelter..." "..the ingenuity to adapt their diet and lifestyle..." "..and, perhaps most crucially of all, the ability to pass the secrets of surviving in this most unforgiving of environments..." "..down the generations." "This is it, the human brain and it might not look like it, but it's the most complex physical structure we know of, anywhere in the universe." "There are over 80 billion neurons in the average human brain." "That's comparable to the number of stars in a galaxy." "That doesn't even begin to describe its complexity." "Those neurons form connections between 10,000 and 100,000 connections to other neurons and it's from that complex circuitry that the human condition emerges." "Everything that makes us who we are comes from this kilogram and a half of matter that resides in the skull of every human that has ever walked the Earth." "So who are we?" "Well, a possible answer is that we are something that emerges from electrical activity inside this impossibly complex blob of matter." "You know, I love Ethiopia and not just because it's a beautiful country but because of an idea." "It's impossible to sit here and not catch a glimpse out of your peripheral vision of a line of ghosts stretching back 10,000 generations because we are all related to someone who lived here" "200,000 years ago." "And those first Homo sapiens weren't that different to us - in many ways they were the same." "So if you could bring a newborn baby from the Rift Valley all those years ago to the 21st century and subject it to a 21st-century education, then there's no reason why it couldn't achieve anything that a modern child could achieve." "It could even be an astronaut." "The brains that take us off our planet... ..that build spacecraft..." "..and enable us to live in the vacuum of space... ..are the same brains that once fashioned spear points on the plains of Africa a quarter of a million years ago." "But if those brains have barely changed since we first evolved, what was it that took us from the Rift Valley to living amongst the stars?" "The road to civilisation began 60,000 years ago when modern humans first left Africa." "They moved north through the deserts of the Middle East, forging the routes the Bedouin still use to this day." "2,000 years ago, this part of the Jordanian desert was home to the Nabataeans and, for millennia, they lived a nomadic lifestyle, so living under canvas and driving their camel trains along the ancient trade routes that snaked across the desert." "But some time around 150 BC, they decided to try something different." "This is the Nabataeans' great capital, Petra." "It stands testament to the moment they abandoned their traditional way of life and built a civilisation in the desert." "This is probably the most famous building in Petra, it's called Al Khazneh, which means treasure box, after a Bedouin legend that a Pharaoh hid an urn of treasure there." "Although its precise function is lost beneath the sands of time, the sheer scale of these buildings serves a far deeper purpose." "Monumental architecture is a key feature of human civilisation - a statement of power and grandeur." "It cements the place of the rulers and therefore provides stability and security." "And this is one of the main ceremonial routes into Petra, but this isn't the tradesmen's entrance, you know, dignitaries, important people from across the ancient world, from Mesopotamia, from Rome and Egypt would have entered Petra here." "Just imagine what it would have been like." "The city sat on a trade route which brought wood and spices and incense and dyes up from Africa and India and into the Mediterranean, black pepper alone fetched 40 times its own weight in gold in a Roman market," "and this city controlled all that trade and they taxed it." "Every rock you see on every hillside right across the city is not actually a rock, it's a brick because these hillsides would have been covered with houses and temples and palaces." "And then all these stone facades would have been covered in white plaster and painted bright colours and not only the temples and houses but every tomb on every mountainside - this city would have been a magnificent sight." "At its peak, Petra had a population of 30,000..." "..but today it lies empty and abandoned, as it has for nearly 1,500 years." "Its only occupants a handful of Bedouin tribespeople who've made their home amongst the ruins." "So what was it that enabled the ancient Nabataeans to support a metropolis here in the desert?" "The Nabataeans were masters of fluid engineering and virtually every drop of rainwater that fell on this landscape was captured and channelled in grooves that they cut into the rock and stored in giant reservoirs and cisterns like this one." "They were better at plumbing than the Romans, they had the first ever pressurised water system and they used it to deliver 12 million gallons of water every day into the city of Petra." "By carefully managing this precious resource, the Nabataeans sustained their city and flourished here for seven centuries..." "..because with water came the thing that underpins all civilisation." "Ali Abdullah is part of the farming tradition that goes back further than anywhere in the world..." "..because it was here in the fertile crescent 11,500 years ago that the first agriculture emerged..." "..closely followed by the first civilisations." "The reason agriculture is so important for the development of civilisation is because it supports large numbers of people in one place." "It also frees up people's time - they don't need to spend all their day toiling in the fields, so at least some of them can do other things like think, or become experts and, ultimately, build that civilisation." "The human brain is what separates us from the other primates, but building civilisations requires not just one but many brains working together." "And it was this coming together of minds that led to an innovation that changed who we are for ever." "In 1993, archaeologists discovered a set of around 150 Nabataean scrolls." "Now they date from the last days of Petra as an occupied city around 550 AD." "And the most intact documents a court case between two priests who lived together." "And one of the priests decided to run away and he stole from the house, according to the scroll, a key to one of the upstairs rooms, two wooden beams that presumably held the roof up, six birds and a table." "So he's a bit like a Nabataean Father Ted." "Now, mundane as it may seem, this is probably how writing began - the greatest invention in the history of human civilisation probably arose for admin purposes." "With writing came literature, science, mathematics and engineering." "And, as time passed, so the information held in the written word grew and evolved." "Writing was such an important innovation because it freed the acquisition of knowledge from the limits of the human memory." "Once we could write things down, an almost unlimited amount of information could be passed, not only from generation to generation, but from city to city, from country to country, across oceans, across the world." "Knowledge became widespread accessible and permanent, never lost and always added to." "Writing created a cultural ratchet, an exponentiation of the known, which ultimately led us to the stars." "In the world of space exploration, this room is hallowed ground because every astronaut that flies to the International Space Station today, and, indeed, pretty much every astronaut that's ever flown into space, first American, then Russian and European," "have sat at this table and signed this book." "This is so precious." "It's a tradition that began in 1969 with three Soyuz crews," "Soyuz 6, 7 and 8." "And, as you flick through the pages, you just turn through the history of space exploration." "And here on a visit, 1st June 1970, is Neil Armstrong." "And the reason every astronaut wants to come here and sit at this table is because this table, and all the furniture in the office, everything you see in the office, belonged to Yuri Gagarin." "You know, it's easy to characterise the early astronauts, the pioneering test pilot astronauts, as emotionless people, you know, people who were just interested in flying the vehicles." "But you only need to listen to Yuri Gagarin's words to realise that he knew precisely the significance of what he was about to do." "On 12th April, 1961, we became a space-faring civilisation." "And in 48 hours, the latest humans to sign Gagarin's book are due to make the long journey back to their home world." "This is Kazakhstan, and certainly at this time of year, in mid March, it's a massed, icy wilderness, and it's just flat as far as the eye can see, and for around 800,000 square kilometres, which is basically the" "reason that we're here because we're part of a search and rescue mission." "Tomorrow morning we're going to meet three astronauts out there in the snow, because we're going to rendezvous with a Soyuz spacecraft as it returns from the International Space Station." "The technology that will bring those three humans back to Earth and the physics that will guide them home is the culmination of hundreds of years of knowledge." "Now, even I, just knowing a bit of physics in my head, can calculate exactly what the astronauts have to do to re-enter the Earth's atmosphere - all you need are the two laws written down first" "by Isaac Newton, F = MA and the universal law of gravitation." "Now, what you can show from those, really simply, is that, for a circular orbit, which is what the International Space Station is basically in, the velocity flying along there is given by the square root of GM over R, where M's the mass of the Earth," "and R is the distance from the centre of the Earth." "And the equations tell you that to return to Earth, all the astronauts need to do is reduce that velocity by 128 metres per second, and gravity will do the rest." "And here is the important thing." "I can do that because I know those two equations." "Why do I know them?" "Because I read them in a textbook that was based on Newton's work and published in 1687." "But if I had to do that from scratch, if I had to come up with those two equations, it'd never happen." "Newton was a genius, he worked for decades on those equations " "I would have no chance." "Newton famously said that he built his knowledge, his great laws, on the shoulders of giants, and indeed he did." "It was Euclid, it was Descartes, it was the great mathematicians and geometers, not only of Newton's time and before Galileo, but stretching all the way back to Euclid and the Ancient Greeks, and he got that knowledge from the written word, from books." "So, this is the place where it's going to hit the snow, hopefully tomorrow, although apparently the wind is quite high, so it's possible..." "possible they'll cancel the landing and move it 24 hours into the future." "We're just waiting for a phone call from the Russian Space Agency to tell us whether the Soyuz undocked from the Space Station." "So, fingers crossed we're going to get that phone call, and otherwise we've got enough vodka for about a month." "Right here you can see in the foreground the three departing crew members, that's Sergey Ryazansky on the left there, Oleg Kotov in the middle, and just floating to the back, in the grey jumpsuit, is Mike Hopkins." "There are Kotov and Ryazansky, giving the final wave goodbye." "Once the hatches are closed, the Soyuz, containing its three human passengers, undocks..." "Physical separation confirmed." "Confirmed at 7.02pm central time." "..and the tiny craft gently drifts away." "Separation." "Copying, looking good.'" "This is the GPS system in the car, and it's just ticked over to 08.30 now, so that means now, this moment, the Soyuz is firing its rockets - that's going to change its orbit," "it's going to slow it down in its orbit." "So instead of following the International Space Station and orbiting around the Earth, it takes a more elliptical orbit and drops towards the Earth's atmosphere." "This view from external cameras on the International Space Station showing the entry of the Soyuz vehicle as it barrels through the Earth's atmosphere." "The capsule glows white hot as it slowed from 26,000 to just 800 kilometres per hour by the time its parachutes open." "A rare view of the Soyuz, streaking towards the central steppe of Kazakhstan." "I've got to say this is one of the most exciting things I've ever done, waiting for a spaceship to return from the International Space Station, it's just..." "Go." "Nobody can see it at the moment, but it should be there." "There it is, there it is." "We're right there, I can see the parachutes." "We're the first there, we're the first vehicle there, actually, although there's one after." "It's quite remarkable." "You can smell a faint... ..faint burning smell, not surprisingly - you see the, yeah, damage." "Well, the sacrificial heat shield that's burnt away to protect it on its way to re-entry." "This is incredible " "I can't believe you can just stand next to a spacecraft." "But the..." "If you turn around now, the first astronaut's going to come out," "I think it's going to be the captain first." "You can see what a physical experience it must be - not only the re-entry, which is, you know, ONLY an hour and it probably pulls four or five g, but after living on the space station for six months, to feel Earth's gravity," "to feel this cold air again, er, it..." "They look very happy, they're all smiling, but they look absolutely knackered." "A single human lifetime ago, 60 or 70 years, this journey would have been unthinkable, but now, in the 21st century, it's routine - four times a year astronauts make the journey from our permanent home in space back to planet Earth." "But, to me, it's much more than that, because this space travel, the exploration of the universe, is the ultimate expression of a much grander journey." "After almost 14 billion years of cosmic evolution... ..and some four billion years of life on Earth..." "..the universe became conscious." "And in just 200,000 years, we humans have transformed ourselves beyond all recognition." "We've built great civilisations... ..accumulated knowledge and technology... until, finally, apeman..." "..became spaceman." "And, like all journeys, like all great adventures, our journey just began with a moment."