Stone Age Apocalypse Naked Science

a hundred thousand years ago up to a million humans roam beer and yet about seventy thousand years ago a population of just a few thousand people may have given rise to all modern humans something happened something big something that changed the course of human development how did this happen and as our 21st century civilization faced the same terrifying threat there are more than six billion people alive in the world today humans have adapted to the different conditions across the planet by developing a wide variety of different physical characteristics we come in a huge range of colors shapes and sizes but the really interesting thing is not how different we appear on the surface but how similar we all are underneath professor Todd DISA tell of New York university studies DNA a kind of human barcode for our inherited physical characteristics it turns out there is a difference of only about 1/10 of 1% in the genetic information held in the DNA molecule between any two people however different they may look and wherever in the world they originally come from we all have more in common with each other than we might have thought I find it absolutely fascinating how little genetic diversity there are amongst the people throughout the world you see people of different skin color head shapes hair types and all of those things those differences seem to really be skin deep when we get down to the genetics in fact there is less variation in the DNA of all of the people alive on the planet today that exists in just one troop of chimpanzees in West Africa the small genetic diversity in our huge population may tell us something important about our prehistoric past that something happened to erase most of the human DNA record something that could have decimated the numbers of our ancestors it's called a genetic bottle a population collapse that wipes out much of the DNA record nowadays they're commonly seen in endangered species it's like what happens if you shake a range of colored balls out of a glass container here I have a large variable population represented by the fibers colored gums if this population strengths by going through what we call a genetic bottleneck here actually represented by a real bottle I end up with a smaller pool of West genetic diversity the human DNA record suggests that something may have driven our ancestors to the brink of extinction the evidence in our genes may also tell us when this happened and how many prehistoric survivors made it through the genetic bottleneck scientists can estimate the size of human population from the past using mitochondria a sort of cellular battery pack that has its own DNA mitochondrial DNA is only inherited from the mother and does not combine with genetic information from the father so starting with the total range of these genes identified in our modern population scientists can track back along the exclusively female line and estimate the number of childbearing women in the population of earlier generations and the DNA that is passed to a child is not always a perfect copy of the parental DNA it's a bit like photocopying a photograph and then photocopying the copy over and over again each imperfection carries forward to all the subsequent copies and over time the picture can change significantly so this is how I mutate after 20 generations of photocopying scientists can estimate the date and human population after a genetic bottleneck by comparing the rate of mutation and a present range of mitochondrial DNA variation by looking at the pattern of mitochondrial mutations that we see on the planet today and using the known mutation rate of mitochondria I can estimate that between 50 and 100 thousand years ago there was only a few thousand individuals that gave rise to the populations that we see on the planet today in other words every single one of our 6 billion plus population may be directly descended from a tiny group of people maybe even as few as five thousand in total who live between 50,000 and a hundred thousand years ago that's equivalent to just one person for the entire modern population of Manhattan if this atoll is correct then we all owe our existence to these few thousand survivors yet there may have been as many as a million prehistoric people alive before the start of the genetic bottleneck stone tools from more than a hundred thousand years ago have been found as far apart as northern Europe and China but how far had our species developed by this time were any of these creatures really human the Natural History Museum in London is home to one of the largest ancient fossil collections in the world dr. Chris stringer examined specimens from the collection to investigate how far our ancestors had evolved by the time of the earliest predicted start of this population bottleneck geneticists estimate that human evolution started about 6 million years ago when the DNA of chimps and our species first separated but the earliest signs of distinctly human characteristics emerged several million years later by about two million years ago we appear to have the first creatures we can call human the face is starting to show human features we've got the beginning of the development of a prominent nose the base of the skull shows us that these creatures were walking upright and we've got the appearance of stone tools paleontologists use brain size traditionally measured from the volume of beads that fit in a skull as a marker of human development this 2 million year old human had a 600cc brain much larger than a chimpanzee but less than half the volume of a modern human over the thousands of years that followed human brain sight is increased by 100 thousand years ago fossils such as this skull from Israel had modern human dimensions essentially this is a modern human skull and it shows us that modern humans had evolved by this time they may well have appeared first of all in Africa as far back as two hundred thousand years ago by then early humans were producing a more sophisticated range of tools to meet different needs in this case this tool was probably used for scraping surfaces but we find they're shaping spear points they're shaping tools probably for working wood and so we're beginning to get the evolution of specialized technology and there are even clues that they were starting to think like us we've recently discovered evidence of symbolism from a hundred thousand years ago we've got shell beads so people are using body adornment they're sending messages to each other if you like the beginning of art and creativity the sort of thing that we finally not only use by 100,000 years ago before the likely start of this genetic bottleneck there were a range of prehistoric people living across much of the planet including essentially modern humans but some scientists believe that this intelligent adaptable species was about to suffer a cataclysmic drop in numbers so what apocalyptic event could have driven Stone Age man to the brink of extinction a massive volcano a terrifying tsunami or maybe a devastating asteroid impact some scientists believe that Stone Age humans suffered a genetic bottleneck between fifty and a hundred thousand years ago from a global population of hundreds of thousands the human race may have been sustained by a small group of only a few thousand people until recently evidence of a catastrophic natural disaster that could have decimated the numbers of our Stone Age ancestors lay hidden in the frozen ice fields of Greenland tiny air bubbles are preserved in the Arctic ice they hold detailed scientific information about the climate from when the water froze global temperatures can be estimated from the thickness of the ice layers aerosol and dust particles record information about natural events from that time scientists can date all this information a new sheet of ice is deposited each year so the annual records pile up one on top of another like pancakes in a diner the individual layers are identified from ice cores long cylinders of ice from below the frozen surface in Greenland that carry many thousands of years of environmental data professor Greg Solinsky of the University of Maine is a leading expert on the study of the ice core record in 1993 he made a stunning discovery in this environmental time machine as I was investigating the record of the sulfuric acid in the ice core I noticed about 75,000 years ago that was this very large spike or a really very high concentration of sulfate to have something that big was just so exciting and I wanted to investigate it more Solinsky had discovered the highest annual acid reading in the entire a hundred and ten thousand year record of the Greenland ice core which points towards a cataclysmic natural disaster this large amounts of uric acid really only has one potential source and that would be an extremely large massive volcanic eruption the unprecedented acid discovery in the ice core came from a huge volcano major eruptions blast out enormous quantities of gases including sulfates which turn into sulfuric acid in the atmosphere the largest acid cloud of the 20th century resulted from the 1991 eruption at Mount Pinatubo in the Philippines which ejected 20 million tons of sulfur dioxide the acid in the ice core suggests that about 75,000 years earlier there was an eruption a hundred times bigger than Pinatubo itself the largest for nearly a century most active volcanoes lie at the boundaries between the vast tectonic plates that make up the surface of the earth the most powerful super eruption of the last two million years happened in Southeast Asia on the Indonesian island of Sumatra Lake Toba is an enormous body of water 60 miles long by 20 miles wide in 1929 Dutch geologist van bellen identified this location as a vast caldera the hole left behind after an eruption has blasted enormous quantities of volcanic material into the atmosphere in fact much of this huge crater was formed following an immense super eruption seventy five thousand years ago in line with the timing of the record acid find in the ice core this eruption three times bigger than the last major event of the Yellowstone supervolcano could be the devastating natural disaster which threatened the very future of our species the shocking power of this volcano results from the chemistry of the rocks deep beneath the surface of the lake Sumatra lies close to the boundary where the indo-australian tectonic plate pushes beneath the Eurasian Plate at a rate of about two inches per year the lower plate releases water causing rock in the plate above it to melt and then rise as low-density magma at surface level this melted volcanic rock becomes lava but it is the potential of magma trapped below ground to hold in gases that creates the explosive power of a volcano dr. David wark of Rensselaer Polytechnic Institute in New York State studies the composition of the magma which caused the Toba eruption 75,000 years ago to understand why this event was so powerful he describes the build-up of the liquid rock in the magma chamber as being like filling a bottle with a fizzy drink like Magma's the soda has dissolved bubbles inside of it dissolved gases you can see the gas is trying to work their way out there with bottles of Cola carbon dioxide can move easily through the drink and escape this is like low viscosity Macke founded volcanoes such as Kilauea in Hawaii where gases bubble up through the liquid rock and lava observed slowly at the surface walk tests magma from the 75 thousand year-old eruption along with a control sample from a nearby Sumatran volcano to demonstrate why the tober event must have been so violent at 1,300 degrees centigrade were more than two thousand degrees Fahrenheit the control sample melts even to the naked eye the sample from the Toba magma is much more viscous and so able to hold in more explosive volcanic gases than the control a powerful microscope highlights holes in the melted Tober material these are the spaces left behind after the huge volume of gases escaped during the super eruption it's the bubbles that are trapped in the trap because of the high viscosity that makes the eruption so explosive 75,000 years ago thousands of cubic miles of magma have accumulated beneath the Sumatran landscape creating irresistible pressures on the surface 200 cubic miles of ash blast out from Toba covering an area more than ten times the size of California over two billion tons of sulfuric acid explode into the atmosphere this is the biggest eruption modern man has ever experienced but how could one volcano drive the human race across the whole of the planet to the brink of extinction close to the volcano the effects would have been apocalyptic imagine pyroclastic flows superheated avalanches of volcanic material they wipe out an area of more than 7,000 square miles of Sumatra they vaporize anybody in their path they extinguish all signs of life across the width of this vast island an eruptive column up to 50 miles high he ejected more than 200 cubic miles of ash into the atmosphere we have experienced the lethal consequences of volcanic ash in recent times when Mount Pinatubo in the Philippines erupted in 1991 the column reached a height of about 22 miles Denis shows was a servicemen stationed at the nearby US Air Base you could see the volcano erupt because it looked like a cloud of ash rolling over the sky looks like something out of a movie unfortunately this was a horror show without a happy ending everything was just gritty everywhere all the branches were gone now all the vegetation was just covered and coated and everything was gone the Pinatubo eruption killed 320 people volcanic ash caused most of the deaths but here volcanologists identified the threat early a mass evacuation saved up to 20,000 lives October there would have been no warning system and the super eruption 75 thousand years ago ejected 200 times more volcanic debris than Pinatubo the ash cloud would have covered an area in excess of a million square miles now a new archeological find gives a unique insight into the impact of this terrible downpour on Stone Age societies in the year 2000 a layer of Toba ash some four yards deep was identified in southern India by dr. Michael Petraglia of the Leverhulme Center at the University of Cambridge it is a spectacular deposit very thick sequence with archeology associated with it it's but one of a kind fine you're pretty far down in the immediate aftermath of the eruption approximately six inches of ash fell on southern India the first threat to the Stone Age hunter gatherers would have come from breathing in this fine powder these particles are like little glass shards and these glass shards if they get into your lungs they can cause all sorts of damage once this deadly volcanic debris had settled it polluted the environment the prehistoric hunter-gatherers lived off this dust gets into water and you have to drink it it can actually turn the water into poison they are ancient plant fragments that I'm pulling out and some of these plants might have died because of a super eruption itself the fall of an estimated six inches of Toba ash on India would have wiped out most plant life because the ash layer would have blocked out oxygen from the air making the soil sterile ash from the much smaller Pinatubo eruption in 1991 devastated hundreds of square miles of agricultural land soil samples from Petraglia site in southern india indicated this area had supported extensive plant life below the ash we find this clay and we believe that marshy types of plants were in this environment this fertile soil was covered in a thick layer of barren ash immediately creating a very hostile environment for vegetation the chemistry of this ash is such that the plants cannot survive in it this deadly ash would have covered much of India over the course of just a few days the landscape would have been blanketed by this ash and therefore plants and animals would have had a very difficult time surviving but the problems created by the ash would have continued for years in this part of the world there is an annual monsoon season in modern India this causes major floods 75,000 years ago this huge yearly rainfall would have continually moved the millions of tons of volcanic matter from the Toba super eruption causing new perils for any Stone Age survivors during monsoon awls seasons what would have happened was the ash on the landscape would have been eroded off into streams and into rivers therefore choking of systems the full yards thick layer of ash that the travelers dig probably built up as monsoon water carried the volcanic debris into waterways blocking up the natural irrigation systems see so you're finally digging any survivors would have faced a bleak future in this barren inhospitable environment archeologists have discovered no human remains beneath the Toba ash layer a collection of Stone Age tools is the only surviving testament to the society that existed here before the super eruption well what's so interesting is that we find these in great abundance below the ash but once the ash came it seems that those populations using these stone tools were no longer there volcanic debris from the Toba eruption threatened hunter-gatherer societies over more than a million square miles but long after the ash cloud scattered Stone Age survivors across the globe faced a second parallel an acid cloud created by the two billion tonnes of sulfates blasted out by the supervolcano acid droplets in the stratosphere would have blocked out much of the sunlight triggering a global six year volcanic winter professor howard Griffiths of Cambridge University investigates the impact of this sudden climate change on plant life what our experiments have done of mimic the effects that we'd expect to see following that volcanic eruption we have reduced the light intensity we've reduced the temperature and we've reduced the water availability for plant growth acid from the Toba eruption cut out up to 90 percent of available sunlight but plants use energy from the Sun to grow in a process called photosynthesis Griffiths investigates the impact on his test specimens of dropping to the lowest light levels of the volcanic winter what we've got here is that the leaf has now stopped photosynthesizing altogether so growth would stop below sunlight levels resulting from the Toba eruption could completely halt plant growth but the acid cloud also reduced global temperatures by as much as 30 degrees Fahrenheit griffith supplied this additional trauma to the experimental plants over a period of two weeks here you can see there's an immediate effects with rather yellow gaps indicating a loss of photosynthetic activity the low temperatures has really reduced the potential of this plant for brother to make matters worse the volcanic winter would also have triggered a tenfold drop in rainfall in some areas a microscopic examination of test specimens that have suffered all of these environmental changes suggests that the combination of reduced sunlight temperatures and rainfall would have had a devastating effect on vegetation following the Toba eruption what our expenses have shown is that the combined stresses are predicted to have accompanied the Toba eruption will have the effect of basically deforesting and defoliation the entire environment the super-eruption 75,000 years ago caused a terrible volcanic winter that laid vegetation across the planet to waste this could have decimated most modern human populations for the were survivors and it is their descendants who went on to make the world we know today so who were these people geneticists can trace the movement of early humans by comparing DNA variations in different parts of the world the region with the greatest genetic diversity is the most likely source of populations with more limited DNA variation professor Todd digital of New York University compares this to a deck of cards if I take a full deck of cards in a shuffle and then I deal them out they'll be hearts they'll be clubs they'll be spades they'll be diamonds then if I only take a small group of cards let's say they're all red no matter how often I shuffle that all of the hands that I deal will always be red so the greatest diversity we'll ever find is always from the founding population in this case the full deck of cards this pinpoints the most likely source of modern humanity to the region with the greatest genetic diversity East Africa in fact there is likely to be more difference between the DNA of two neighbors in one village in East Africa than between a person of Southeast Asian descent and a person of Northern European descent the diversity that we see basically around the planet seems to be traced back to East Africa many experts believe that our entire 6 billion population came from a band of only a few thousand people from East Africa about 60,000 years ago but there is archaeological evidence of up to a million humans living across much of the globe tens of thousands of years earlier something seems to have happened to halt human development across most of the inhabited world in a kind of prehistoric game of Risk the Tobi's super eruptions seventy five thousand years ago caused a devastating global volcanic winter a small band of East African survivors of this apocalyptic natural disaster may have sustained the entire human race professor Stanley Ambrose of Illinois University believes that the super eruption did trigger a genetic bottleneck and he has a theory on how a small group of East African hunter-gatherers adapted their behavior to its stun the harsh aftermath of the Toba volcano I think Tovah changed the course of human history by forcing people to become co-operators as opposed to selfish defenders of their small territories Ambrose believes that just a few thousand of our prehistoric ancestors survived the genetic bottleneck by learning to work together building up support networks and developing more sophisticated forms of communication he bases his theory on the movement between Stone Age communities of the materials used to produce prehistoric tools in Kenya and in particular on a type of volcanic glass formed from lava called obsidian things that made it City and so valuable was that it was so sharp like broken glass which is what it is that you could actually shave yourself with it razor sharp tools were a precious commodity in Stone Age times people would have gone to great lengths to acquire obsidian it is possible to work out which volcano the obsidian originally came from so archaeologists can use it to track movement across the prehistoric landscape Ambrose discovered that the tool making materials and sites from before the Toba eruption were nearly all sourced locally the stone came from inside the territorial boundaries of the hunter-gatherer community that lived there suggesting that there was little communication between groups a volcanic winter triggered by the super eruption when temperatures in Africa dropped by up to 30 degrees Fahrenheit rainfall fell by up to 90 percent and much of the vegetation died seems to have changed this at archaeological digs from after Toba such as this one year and took her 60 miles west of Nairobi most of the tools are made from obsidian which stone 8 settlers had carried much greater distances from territories inhabited by other groups no there's a piece of obsidian it's likely to have come from about 70 miles away when I find obsidian out here it doesn't just mean to me a stone tool which symbolizes relationships and the ability to get across the territory the movement of the obsidian suggests that people traveled further in search of scarce resources in the Bleak aftermath of the super eruption but as Ambrose demonstrates when he retraces the root of our Stone Age ancestors to the obsidian source at Crater Lake quarry this is a tough territory to cross driving around the African landscape it's difficult enough doing it on foot with wild animals must have been a really incredible challenge to do an experiment at Kenya's Hell's Gate National Park shows how gruelling the 70 mile journey to the Obsidian source would have been on foot Daniel Shaw is a fit healthy guide from a nearby masai village he starts adorned from a local landmark fisher's tower and sets out to walk as many miles as he can through this tough terrain before returning here at sunset Shaw covers a fraction of the 70 miles separating the Stone Age settlement and crater lake quarry over the course of an exhausting 12-hour trek he's worked 14 point 8 eight miles prehistoric humans could have taken several days to get to the Obsidian source crossing the territories of other hunter-gatherer groups on the way either avoid encounters with the people who lived in this area or have very good relationship they probably prefer to have good relationships because I don't think any rock is worth your life Ambrose believes that the tough East African terrain would have forced people to cooperate with their neighbors as they sought high-grade tool-making materials from obsidian sources such as crater lake quarry I think this is a great place to come and collect obsidian if you're a stone age person because you can pick and choose the pieces you like very easily so it's sort of like a supermarket where you can just come and pick what you'd like off the shelves this site lies on the edge of an ancient volcano the obsidian was originally magma that rose when the volcano was active and became lava at a surface this glass probably cooled very quickly and when it cools quickly it prevents crystals from forming the quality of the obsidian will also depend on the chemical composition of the lava and on how the rock is preserved in the earth the obsidian at this site can be easily worked to produce the razor-sharp edges our prehistoric ancestors used for hunting and preparing meat this kind of volcanic glass is very good for making stone tools because it has such a fine grain or no grain at all and that makes the edge extraordinarily sharp and there is still evidence at the site of the quarrying work of the Stone Age hunter gatherers well what we see here is a very large block of obsidian that looked quite desirable you can see here where they tried digging it out and I think they gave up it may have been just too much work may have been in a too precarious of position or it may have just been too big to carry but it's a nice piece the sophisticated tools that can be made from high quality obsidian would have helped the ancient africans to survive in the barren post Toba landscape but ambrose believes that the communication skills people learnt as they collected tool making materials would prove to be more significant over the centuries that followed the fact that people came from such long distances implies a new set of skills for negotiating travelling across people's territories I think that was the last step in the development of language he believes that new skills our ancestors developed in the tough climate after the Toba eruption changed the course of human development across the planet towba probably ultimately allowed people to get out of Africa and populate the rest of the world this was just the beginning of a revolution that I think has continued if the Toba theory is correct then all of the six billion people alive today are descendants of a group of just a few thousand people from Equatorial Africa who learnt a whole new set of skills to survive the horrifying aftermath of this super eruption so are there any lessons for us here in the 21st century if the Toba supervolcano made our modern civilization could it also destroyed 75,000 years ago the most powerful supervolcano modern man has ever experienced erupted in Indonesia it may even have driven the human race to the brink of extinction lake toba on the island of Sumatra formed in the crater left behind after two hundred cubic miles of ash had blasted into the atmosphere nowadays this is a peaceful place inhabited by fishing communities and visited by tourists intrigued by this vast lake and the hot springs that are a rare reminder of its volcanic past but this calm could be shattered at any moment in this region of high seismic activity December 2004 an earthquake in the Indian Ocean launches the most deadly tsunami in history raising fears of new volcanic activity in Indonesia the vast readjustment in the Earth's crust which triggered this tragic series of events happened on the Sumatran fault part of the same geological system that caused the super eruption on the island seventy-five thousand years earlier many scientists believe there is a direct link between earthquake activity and volcanic activity but for tobert to erupt it would need to have a large volume of magma already built up beneath the surface professor Rob McCaffrey of Rensselaer Polytechnic Institute in New York State made a study of volcanic activity beneath Lake Toba in 2001 a simple demonstration in the college grounds shows how he was able to use sound waves to understand the subterranean geology in Sumatra students position a series of sensors at equal distances from a source of sound waves in this case a hammer there you go the sound waves from the hammer blow moved through different materials at different speeds so even though the sensors are the same distance away it reaches some of them more quickly here's a good one waves that travel through the walkways arrived sooner than the waves that travel through the soil underneath the grass that's because the walk waves are much more consolidated so by analyzing sound waves at different points scientists can build up a picture of the geological features they have passed through McCaffery sets up sensors around Lake Toba to measure the sound waves generated by low-level earthquakes his readings reveal an immense volcanic system hidden deep beneath the lake our tomography results suggest that there are two separate chambers a large one in himself and smaller one in the north and there's an alarm there are signs of new activity at Toba if we're interpreting these things correctly it looks like there is magma feeding directly into the chamber and rejuvenating them the volcano today there is still volcanic activity at the site of the largest eruption of the last two million years to determine if a major new eruption is imminent experts look for telltale signs of movement in the ground above the magma chamber in 1993 McCaffrey took GPS positioning measurements all around Toba in 2001 he returned to the site to look for surface changes to our surprise things just weren't moving at all we could measure to within 1/16 of an inch and at that level we didn't see any movement at all and I would say that I don't expect anything catastrophic to happen it tobei within my lifetime anyway towba may be safe for the immediate future but what about the dozens of other ancient supervolcano sites including perhaps the most famous at Yellowstone National Park at Yellowstone there is clear evidence of a volcanic past in the rugged landscape and a series of geezers fumaroles and hot springs reveal continuing subterranean activity enough to have raised fears of a new super eruption brewing beneath the surface here the problem is that we have no record of exactly what the warning signs are for these cataclysmic events and this is one of the greatest concerns for professor bill McGuire director of the Benfield hazard Research Center at University College London the trouble super-eruptions is that we've never experienced one in modern times so we don't know exactly what we will see before one of these eruptions we may get months of warning we may only get weeks we may only get days we don't even know where the next super eruption is likely to happen they may occur where there hasn't been any eruption before so magma may have been accumulating of the last few hundred years but in the first we will know that it is when that magma breaks the surface and we get one of these huge eruptions and super eruptions like Toba are on a completely different scale from the volcanoes we have experienced in modern times such as Montserrat in the Caribbean Etna in Sicily or Mount Pinatubo in the Philippines if this fall represents the volume of material ejected by Pinatubo which was one of the biggest eruptions of these the 20th century then this basketball represents the amount of material ejected by the Toba eruption that Pinatubo actually cooled things down by by maybe half a degree it actually slowed down global warming so you can imagine what an eruption of this size would do to the global climate our modern infrastructure is not designed to cope with Toba level climate change like temperature drops of up to 30 degrees Fahrenheit or 90% rainfall reductions a modern supervolcano could be a thousand times more devastating than the worst natural disasters on record I think the next super eruption will kill perhaps a billion people through starvation it will bring the global economy to the edge of complete collapse and it will be the greatest disaster that our civilization ever had to cope with the awesome dimensions of the Toba caldera are a somber reminder of the power of nature the super eruption here 75 thousand years ago may have threatened the very future of the human race the chances of a similar apocalyptic event in the 21st century are certainly low maybe just one in 500 but the consequences could be just as devastating

Channel: Lekisha Alston

Views: 30,591

Rating: 4.4252872 out of 5

Keywords: 2015, geographic, hindi, documentary, wild, snake, hd, animals, channel, in

Id: JxIualhJBEY

Length: 46min 25sec (2785 seconds)

Published: Mon Aug 31 2015