"This is our world." "We have shaped it in our image." "Made it our own." "We are now the only humans in existence." "Absolute rulers of the Earth." "But there was a time when we shared this planet with other, very different types of human." "By the time our ancestors left Africa around 100,000 years ago, most of these "others" had gone extinct." "But not all." "Other species had made the journey out of Africa before us." "Smart, strong and well adapted to their environment, they were the dominant species on the planet." "So what happened when our worlds collided?" "Why, despite all their advantages, were those others driven to extinction?" "Why, against the odds, did we win the Battle For Planet Earth?" "Around 100,000 years ago, a new species of human arrived in what is now India." "The colour of their skin betrayed their African origins." "They had language." "They lived in small, tightly-bonded family groups." "These were Homo sapiens - modern people." "They were us." "Their numbers were few, and from Africa they had begun to spread slowly across the world." "But Asia was already occupied." "Home to a different human species " "Homo erectus." "Erectus was a fascinating species, it lasted for a very long time." "It's really the longest-lived human species we know about." "These are people that are being very mobile, in open country, to get to their food, and often to get to their food ahead of the competition." "So in that sense, they're very like us in terms of their overall body shape and body build." "No water." "Come." "Although physically similar, any chance of a peaceful co-existence between Homo sapiens and Homo erectus was shattered by a cataclysmic event that took place over 2,000 miles away." "The eruption of Mount Toba in south-east Asia." "74,000 years ago, it erupted on a scale that no human had experienced before or since." "It's certainly the largest volcanic eruption of the last two million years and erupted a huge amount of material." "And because of its magnitude, it's been classed as a super-volcanic eruption." "The fallout from the eruption extended as far as the Indian sub-continent." "We've got areas, particularly in East India, where the ash reaches six metres in thickness." "Ash fall from the eruption filled the atmosphere with toxic chemicals... ..turning rain to acid that poisoned lakes and rivers..." "..intensifying the struggle for survival." "In the aftermath of the Toba eruption, you might have increased competition because, remember, plants and animals are suffering and these small groups of hunter-gatherers are competing for diminished resources and so that may have caused some situations" "where there was conflict between groups." "Based on the latest archaeological and scientific evidence, this is a dramatisation of a world forged by the Toba eruption." "A time which shaped the fates of two different but closely related species." "Us...and them." "Leave it." "Water!" "Wait!" "Baako, wait!" "Drink." "Don't drink it!" "What are you doing?" "How do you know the water is good?" "People were here." "They lived here." "Why do you think they left?" "The people, did they go to the mountains for clean water?" "These are NOT people!" "As the once-lush Indian landscape turned to desert, clean water became scarce and increasingly hard to find." "We'll find somewhere for you to rest." "Up there." "The Toba eruption was so vast, it would have affected the whole planet." "In the aftermath, human numbers fell dramatically." "We were threatened with extinction." "In India, the struggle to survive would have been particularly harsh." "This was erectus territory." "For thousands of years, erectus had been one of Asia's most successful predators." "The arrival of modern humans would have threatened their world." "We're talking a different species of human." "Erectus was a much more ancient species of human." "So we've got this very strong brow ridge at the front, a long and low skull." "A big face." "Overall bigger teeth than us." "If we had the lower jaw, there wouldn't be a chin on the lower jaw." "So overall, much more robust." "The skull is thicker, muscle markings are very strong." "She's sleeping, but needs water." "What are they if they're not people?" "All I know, I know from stories." "And from my father." "They move fast, like us." "They hunt." "They kill." "If someone comes near... ..they will snap a twig." "And Mother will hear." "You will hear them." "I will come with you!" "Stay with your mother, she needs you." "If I do not return, keep our family alive." "The first human species to walk fully upright, erectus, would have made formidable opponents." "This is a cast of a thigh bone or femur of Homo erectus from Africa." "It tells us Homo erectus was similar to us below the neck." "More particularly, this ridge on the back of their thigh bone, this is the pilaster, and it grows in response to running." "People today who have similar kinds of ridges on their femurs and have femurs of similar sorts of shape like this tend to be very good runners." "We're talking about people, Olympic athletes." "If they were around today, chasing people around, you'd be in trouble." "These guys were like wolves with knives." "With bodies beautifully evolved for running, erectus were the first human species to hunt big game." "To begin with, erectus was scavenging, so picking up the meat from other animals that had done the killing." "But by the end of their time, they were certainly big game hunters, and were capable big game hunters." "Hunting big prey would have required erectus to work co-operatively, in packs." "Mother." "SCREAM" "Cunning carnivores at the very top of the food chain, erectus were armed with a lethal stone weapon." "It looks just like a rock." "But if you look more carefully, you can see it has a very sharp cutting edge that goes around its circumference." "It's also thin, a cross section, so you have a very sharp edge." "And from what we can reconstruct of its use, it was used mainly for cutting the limbs off of an animal." "It's the Stone Age equivalent of a chainsaw." "For cutting through skin." "Cutting through muscle." "Cutting through tendons." "If you're using this as a weapon, it would create a pretty nasty slashing wound." "Like that." "Yeah, it's all-purpose knife." "No, go away!" "Mother!" "Leave us alone!" "No!" "Although we think of necklaces as a way of dressing up, for our ancestors, they had a much more important role." "Recent human cultures used beads and other personal adornments to transmit information, in a way." "Certain combinations of shells can symbolically convey information about the person wearing them." "Personal adornments, symbols like this, can be ways that people can establish communications and relationships across great distances, so it's kind of like a passport when you think about it." "Beads like these helped us to identify friend from foe, allowing us to form alliances with others." "Where's your father?" "He went to find water." "They took him." "Who took him?" "Did they see you?" "Did they see you?" "Did they see you?" "To the rock." "Quick!" "The ability to track evolved with the ability to hunt." "Homo erectus were the first humans to systematically track their prey, using scent, sight and sound." "Their large brains could interpret signs, work out the movements of their prey, making them deadly hunters." "Our ancestors, however, had a significant advantage." "We had learned to anticipate the thoughts and behaviours of others, and use that knowledge to outsmart them." "Find your footprints where you came down." "Step in them backwards." "Backwards!" "Keep going." "Stop!" "What are you staring at?" "HE ROARS" "Go!" "Stay on the rock." "They have father's spear!" "There is no evidence that Homo erectus made spears." "Even if they had, they couldn't have used them the way we do." "Their shoulders lacked the ability to twist, so their palms faced forwards, instead of hanging sideways as with modern humans." "So even if they had invented the spear, they may not have been able to throw it." "In the hands of our ancestors, the spear became a very effective weapon." "The most important advantage of this kind of weapon is that it allows the person using it to put some distance between them and the tip of the spear." "Whereas with a hand axe, you're using the weapon close up." "In this case, you have a long distance between yourself, your hands, and the part of the tool that's doing the killing." "The spear was also effective close up." "Here you can see the kind of wound it makes." "A big slashing wound." "You can see the point's inside the abominable cavity there and the animal's moving, the movement of that point will cause damage, it will cause haemorrhage, cause the animal to bleed out and die more quickly." "The spear wasn't our ancestors' only weapon." "I will keep you safe." "Not with a spear." "The point is sharp." "Hmm. "The point is sharp."" "Throw a spear once, then what?" "Keep watch." "At some point in the distant past, they developed something very new." "One spear." "Many stones!" "Here." "The slingshot, like the spear, gave our ancestors the ability to strike and kill from a distance." "If you hit a small animal with this, it's like hitting you or I with a car." "It'll crush bones, it'll stop it in its tracks." "This is a weapon that allows you to go after birds in flight, rabbits on the move, deer, creatures like this." "It also has value as an offensive weapon in warfare." "You know, David and Goliath." "These things are really dangerous, no joke." "Even in modern conflicts, people armed with these things have been known to kill other people." "It can cause devastating injuries, one of these things against a limb will break a bone." "If it hits your head, it can kill you." "In the 1.8 million years Homo erectus had been on the planet, their weapons technology hadn't progressed beyond the hand axe." "A highly effective, multi-purpose weapon, it was portable, simple to make, easy to replace and the perfect tool to cut, sever and smash." "But it was limiting in one crucial way." "To kill, erectus had to get close." "For the first time, Homo erectus faced competition from a species who weren't bigger, stronger or more numerous, but who simply thought about things in a different way." "It's worked." "They've gone." "You drank bad water." "You should know better." "Water?" "What else?" "Fragments of fossilised ostrich egg shells from the Thar desert in India suggest that our ancestors may have used these eggs to store and transport water." "Just as the San bushmen in Africa have been doing for centuries." "This ability to plan ahead was something our hominid rivals lacked." "Homo sapiens' brain is about a third larger than Homo erectus' brain, and that tells you something." "Brains are expensive tissues." "It costs a lot of calories to grow a big brain." "So there has to be some payoff for that extra brain." "We think the payoff for Homo sapiens is more complex thought, where they are able to plan more complex activities, store more information." "Homo erectus wasn't stupid, but Homo sapiens may have had some key advantages as a consequence of having a larger, more complex brain." "Another advantage we had was language." "Differences between our and their linguistic abilities can be seen by comparing skulls." "The part of the brain that controls language and speech production is located right around here." "And you can see these parts of the Homo sapiens' brain are very much enlarged." "That part of the skull bows outward quite a bit, and so there's more brain in that part of the head." "On the corresponding part of Homo erectus' skull, the brain is relatively small." "So the Homo erectus brain is not devoting a lot of space to the parts of the brain that controls language and speech." "One of the crucial elements of Homo sapiens' adaptations is that it combines complex planning, developed in the front of the brain here, with language, with the ability to spread complex plans from one individual to the other individual, to another individual." "Where's it from?" "Far from here." "Before they came and chased us out." "Us?" "You were with others?" "My son... ..his wife, their baby boy." "Enough!" "Don't drink it all!" "There's more water nearby." "No, there isn't." "Here, on higher ground." "There's been no rain." "But father said..." "Your father was wrong!" "There is no water here." "But away from the rock... ..across the sand, there is water." "More water than you can imagine." "How do you know?" "My father told me." "He came from the water." "Inside there is food." "Not in that one, not now." "There is no food on this mountain, but at the water..." "..there is more food than you can eat." "Imagination, the ability to visualise what can't be seen, would prove another defining advantage for our species." "Like us, erectus are believed to have lived in small family groups." "There is evidence that they cared for each other, and looked after the sick and injured." "There are some hints that they may have had a sense of compassion." "Comparable to the things we feel about one another." "There are fossils from the site of Dmanisi in Georgia that hint at this." "One fossil in particular had lost all of its teeth, either to an infection or to old age, or to both, and this individual was so severely handicapped that it would have had to have assistance." "Some other member of its group would have had to help it basically chew its food in order for this individual to survive." "Erectus moved around in search of food and rarely settled for any length of time." "They were using the landscape, they were travelling from one place to another." "And they were probably gathering resources, gathering, you know, plants and they were occasionally, obviously, butchering animals." "So these were, in a sense, small groups of hunters and gatherers." "But after the Toba eruption, there was not much left to gather." "Ash killed off vegetation, leaving little in the way of fruit, nuts and tubers to eat." "They have food." "Meat would have been highly valued." "They have food!" "Meat?" "We must leave." "What about father?" "Forget your father!" "We must wait for him!" "Huh, wait!" "WHISPERS:" "There are no animals here." "I know that smell!" "Tell him." "Tonight, we stay here." "What?" "!" "This is where he will come." "He will not come." "He's a brave man." "He's strong." "At first light, we go." "With or without him." "Father's alive." "I know he is." "WANGARI GRUMBLES IN HER SLEEP" "WANGARI SNORES" "She even talks in her sleep!" "Shhh." "Respect your elders." "She talks too much." "I don't like her." "I don't like her, but she knows things." "And she has water." "We could take the water and leave her." "Shall we?" "Go back to sleep." "HE GRUNTS WITH EFFORT" "HE COUGHS" "Baako." "Baako!" "Father!" "HE ROARS" "She's gone." "Like other large predators, erectus were territorial, hunting within boundaries and defending their territory from other competition." "She left this." "Territory based on high ground would have been especially prized, because it makes spotting prey easier." "I saw father on that ridge... ..with the others." "Anything that strayed into their territory would have been treated as food." "Don't be afraid." "Footprints." "Everywhere." "Recent studies suggest that erectus were infected by tapeworms, which you get from eating raw meat." "It seems that erectus liked his food red and bloody, even though he could have cooked it." "HE SNIFFS" "They were here." "Where are they now?" "I don't know." "Just stay here... ..and watch." "Father?" "HE GASPS" "Mother!" "On some occasions, Homo erectus's hunger for meat seems to have got the better of them." "The fossilised remains of an erectus found in Kenya shows signs of vitamin A poisoning, probably caused by eating too much animal liver." "Excessive vitamin A causes tissue around bones to tear and bleed." "This person would have been in agony for months." "To survive as long as they did, they must have been cared for by other members of the group." "Baako!" "Friend or enemy?" "Think!" "HE SIGHS" "Father." "He'll protect you." "It's yours now." "Would Homo erectus haven eaten a Homo sapiens, given the chance?" "My guess is, "Yeah."" "They probably didn't view each other as members of the same species, and just as humans today will eat chimpanzees as bush meat," "Homo erectus may have felt the same way about Homo sapiens." "They may also have been cannibals." "Homo erectus bones have been discovered with cut marks, suggesting that the flesh was prised off the skeleton." "Quick!" "Toka?" "Ta!" "ERECTUS YELLS" "HE HOWLS IN AGONY" "Go, Mother." "Go!" "THEY CALL TO EACH OTHER" "Keep going!" "No!" "Up here, quick!" "Muka, halla." "HE GROWLS IN FRUSTRATION" "Muka." "I can't go any further." "Keep going." "No you go, run." "They're coming." "This way." "This way!" "Quick!" "A unique and crucial development of every human species was to harness the power of fire." "Erectus were the first human species to use fire." "Time is the currency of evolution." "If you have more time, you can do more things." "You can do more of the same thing or you can experiment and do different things." "But it's all underwritten by having time, and fire is one way of providing that kind of time." "Without fire, you're not human." "Both species used fire for warmth, and to cook and dry meat." "Cooking makes meat a more digestible substance and so it reduces the time one has to spend time chewing, frees you up to do other things." "But our ancestors were the first to exploit its full range of possibilities." "When they left Africa, our ancestors most likely followed the coastline as they moved into Arabia, India, South East Asia and beyond." "Close to the sea, they were guaranteed food and fresh water, flowing from rivers into the sea." "But after Toba, their ability to range freely was dramatically curtailed." "Them or us?" "Does it matter?" "Mother?" "To escape from this eruption-ravaged land, our ancestors faced a huge problem." "The Thar desert." "It forms a long, natural barrier between the Indian interior and the sea." "It has been there for hundreds of thousands of years, growing and contracting in response to the changing climatic conditions." "After Toba, the desert dramatically expanded." "So this would have brought colder and drier conditions into the north east of India and this would have... probably enhanced aridity." "So areas such as the Thar desert, for example, may have expanded, or areas like the Indo-Gangetic plain may have been particularly arid." "You might have thought that a desert, hundreds of miles wide, would have trapped any humans in the Indian interior." "But there is archaeological evidence that people did attempt to make the journey across it." "How much further?" "Keep walking." "How far?" "I don't know." "Look!" "Follow me." "We'll lose them in the storm." "Faster!" "I can't!" "They're coming." "Keep going." "THEY COUGH" "Aro!" "Heeya-ha!" "Wa!" "Waa!" "Walk like this." "Wait!" "Stop!" "We can't stop." "Sit!" "There's nowhere to hide." "If you want to stay, stay, we're going." "Here, walk in this and you walk like a wounded animal." "Round and round, backwards and forwards, you lose yourself forever." "Do you hear me?" "No-one can be quite sure how our ancestors made it." "Perhaps by finding water in dry river beds, as many indigenous people in Africa and Asia still do today." "Even in apparently dry river beds, after long droughts, water can still be found in underground reservoirs beneath the sand." "If you know where to look." "Heko?" "Heko!" "Heko." "Heko!" "Heko." "Heko." "The ability to find water in the dry times would have been invaluable knowledge, passed down the generations." "And all rivers, dry or flowing, eventually, lead to the sea." "Come on." "Don't drink it." "Get back!" "Archaeologists working in Jawalpuram in India have found the sort of stone tools made by modern humans buried beneath a thick layer of Toba ash." "Alongside our tools were those of Homo erectus." "Above the ash, only our tools are found." "The lack of evidence of erectus after the Toba eruption suggests that they might have been wiped out in India, never to return." "In other parts of Asia, they hung on." "Fossilised skulls from Indonesia show Homo erectus living here until as recently as 30,000 years ago." "A descendent of theirs, Homo floresiensis, nicknamed the Hobbits, lived until about 18,000 years ago." "But then, having successfully walked the earth for almost two million years, this other human species disappeared." "I think it is remarkable that we have these different human species, and, you know, even 100, 000 years ago we've still got several human species on Earth and that's strange for us." "We're the only survivors of all of those great evolutionary experiments in how to be human." "They did go extinct." "And that, of course, was unfortunate for them, but it made a new opportunity for species like ourselves." "The passing of Homo erectus was a tragedy." "We think of ourselves as so unique and special and all the rest of this, and we do so because there's such a huge gulf between ourselves and our nearest primate relatives - gorillas, chimpanzees and bonobos." "If that gap were populated by other hominids, if we had others, we'd see that gap as not so much a gulf but rather a continuum with steps on the way." "We'd still think of ourselves as special but maybe not so special..." "A little dose of humility wouldn't hurt." "If you went back in time and changed a few parameters of climate and geography, then we could have ended up with a completely different outcome." "Maybe these species would all still be around, maybe modern humans would never have evolved and we'd still have these other species on Earth and not us." "The Toba eruption may have changed the destiny of our species, socially and biologically." "Experts believe that our large brains, significantly different from those of our closest relatives, are the product of an intense process of natural selection which occurred during a period of extreme hardship when population numbers were low." "You're home." "People." "Socially too, Toba left a mark on our species." "Evidence reveals that social networking in surviving humans increased." "Through the exchange of gifts, ideas and even people between groups, our social relationships strengthened and became insurance policies against bad times, greatly increasing our chances of survival." "As climatic conditions improved, our ancestors spread around the world, hugging the coastlines, coming in contact with other Homo sapien groups, forging new alliances." "Then 32,000 years ago, our ancestors finally arrived in Europe, to confront the final challenge in our Battle for the Planet - The Neanderthals." "The way Neanderthals are treated in the popular media is very unfair." "I mean, they were highly evolved humans, in their own way as evolved as we are." "There's no other event in human evolution that captures the public imagination like the encounters between Homo sapiens and Neanderthals." "Subtitles by Red Bee Media Ltd" "E-mail subtitling@bbc.co.uk"