a hellish fiery wasteland a molten planet hostile to life yet somehow amazing this is where we got our start how how did the universe our planet how did we ourselves come to be how did the first sparks of life take hold here are we alone in the cosmos where did all the stars and galaxies come from these questions are as ancient as human curiosity itself and non origins of four-part Nova miniseries will hunt for the answer this search takes unexpected twists and turns imagine meteors delivering Earth's oceans from outer space descend into a toxic underworld with bizarre creatures hold clues to how life got it start and picture the view when the newborn moon 200,000 miles closer to Earth than today loomed large in the night sky this cosmic quest takes us back in time to within moments of the Big Bang itself and retraces the events that created us this place we call home and perhaps life elsewhere in the cosmos coming up tonight the origins of life early Earth was not a Garden of Eden there were no clear blue oceans there were no plants there was no life at all so where could the building blocks of life have come from we think that all the carbon your body arrived on the earth in meteorites like this so it makes you wonder if the building blocks of life were delivered courtesy of comets and meteors could any of the tiny ingredients they carry have survived the landing and if they did how did they generate those first traces of life a walk on the ancient surface of the earth offers clues these are the oldest fossils in the world at about three and a half billion years old life evolved on this planet very early and very fast journey back to an age when invisible microbes ruled the planet and caused the greatest transformation in Earth's history over a billion or two billion years the amount of oxygen that these little creatures produced was enough to actually change the entire atmosphere of the planet the story of how life began on this episode of origins on Nova right now original funding for this program was provided by the Park foundation dedicated to education and quality television and by Sprint and Microsoft major funding for origins is provided by the national science foundation America's investment in the future additional funding is provided by nasa office of space science the Alfred P sloan foundation to enhance public understanding of science and technology and the george d smith fund major funding for Nova is also provided by the Corporation for Public Broadcasting and by PBS viewers like you thank you in the endless reaches of the universe earth seems unique it's a planet shaped and molded by life a planet that six billion people call home today but when it was born some four and a half billion years ago earth was a violent place so hostile it's hard to believe life could ever begin here covered in lava and smothered in noxious gases Earth was a planet under siege if you were human going back into time and trying to stand on the early Earth it would be just like visiting a planet that was not your own this was a hazardous world no doubt about that if you were located in the wrong place at the wrong moment you were simply vaporized it was a planet plagued by catastrophe if you condense all of Earth's history to just 24 hours then only minutes after it formed the entire globe melted and reformed then to make matters worse another planet about the size of Mars slammed into Earth a cataclysm that created our moon but soon after these disastrous beginnings the most radical transformation of all time hit the planet the origin of life so how did life begin well over the years people have come up with some pretty creative answers to this question one of my favorites come from a 17th century scientist who wrote down a recipe for creating life from scratch let's see it says here take a dirty garment place it in a vessel next add wheat then according to the recipe after fermenting for 21 days mice will appear fully formed of course we all know that life doesn't form this way but at some point in Earth's early years life did emerge out of nonliving ingredients and for clues to the real recipe of life we have to go back some 4 billion years to a time when earth was nothing like the planet we know today when we think of early Earth we must recognize it was not a Garden of Eden there were no clear blue oceans there was no clear water there were no plants there was no life at all the young son was weaker than it is today and it's light barely penetrated the atmosphere of carbon dioxide spiked with the pungent fumes of hydrogen sulfide since the atmosphere was thicker and dominated by co2 the earth had a reddish tinge to it it didn't have the familiar blue sky the oceans would have had an olive green color rather than our familiar blue color for about the first 600 million years comets and asteroids hounded our planet a time known as the heavy bombardment these interplanetary missiles measured up to 300 miles across their impacts vaporized earth's oceans and melted what's crust with its extreme temperatures and toxic rain seemingly nothing could survive here what we now think that in this hellish environment life first took hold and today hidden away in remote corners of our planet conditions that in some ways resemble the extremes of early earth can still be found penny Boston and Diana Northup are microbiologists on an expedition to investigate how life can survive in those harsh surroundings buried in the depths of this tropical rainforest is a cave called cueva de VI lose located in southern Mexico it's an underground world laced with hydrogen sulfide a foul smelling gas that was present on earth some 4 billion years ago these relic or antique environments like cueva de luce offer the same kinds of environments that we would have found on early Earth and we're hoping to get clues to work backwards from those as you approach the cave you begin to get these faint whiffs of the rotten egg smell and as you get closer this becomes more intense hydrogen sulfide can be extremely poisonous so the scientists have to wear gas masks inside the cave and carefully test them for leaks have you got everything in there at the levels at which humans can't live very long in hydrogen sulfide you don't smell it at all and it would just simply cause you to go unconscious and die very quickly but can any other forms of life survive in the deep recesses of the cave so toxic to humans here hydrogen sulfide and invisible gas escapes from the underground Springs reacts with oxygen in the water and coats the cave with sulfuric acid the longer it sits there on the walls more acid it becomes and so eventually by the time the drop is falling on you it's a very very acid environment it's very fatiguing and even with the protective masks that we have we pick up loads of toxic gas through our skins and perhaps through tiny weeks amazingly despite the extreme conditions it appears that life is thriving inside the cave it comes in a strange package colonies of single-celled bacteria that forms slimy drips scientists call snottites the snottites are drippy gooey mucousy formations that look like stalactites and that's why they were called snottites but because they resemble strings of snot we believe that the the snotty gooey stuff is to protect them against extreme acidity because when we measure the drips on the snottites they are as extreme as battery acid and so while we find that daunting this is where they thrive bacteria are among the most primitive and most common organisms on Earth like all forms of life they grow adapt to their environment and reproduce inside each single cell bacterium is a molecule of DNA the code of life which allows them to multiply there are millions of bacteria in each snot tight and down in the underground streams penny Boston has found different kinds of bacteria in slimy clumps she calls flem balls in fact the cave is home to a huge number of bacterial colonies and astonishingly instead of being poisoned by the hydrogen sulfide these bacteria depend on it for their survival they take the hydrogen sulfide and they get chemical energy out of it it doesn't poison them it's home sweet home for them and this is a pretty new finding for these organisms conditions on early Earth may have been far worse but these bacteria suggests that primitive life could have thrived in extremely hostile environments but where did the very first life come from for more than a century scientists have known that life is the result of chemistry the combination of just the right ingredients in just the right amount today we know these ingredients aren't things like dirty garments and wheat which people used to think would spontaneously generate mice ingredients of life are actually much simpler all living things from bacteria to mice to you and me a made from a small set of chemical elements hydrogen oxygen carbon nitrogen four of the most common elements in the universe combined in just the right way these are the fundamental ingredients of life and carbon is the star of the show carbons everywhere it's all over the universe what makes carbon special is the kind of bonds that it makes both with itself and with other elements we know of no other atom that has the flexibility that carbon has to form diverse types of compounds and the idea that life could have started when carbon and other ingredients combined in the harsh conditions of early Earth was first put to the test in the 1950s by a young graduate student named Stanley Miller to simulate the newborn earth in the lab Miller assembled a contraption made out of flasks and tubes he filled one flask with gases thought at the time to represent Earth's primitive atmosphere and he connected that to another flask with water to represent the oceans and then he did a brilliant thing he simply put an electric charge through that to essentially simulate lightning going through an early atmosphere and after sitting around for a couple of days all of a sudden there was all this brown goo all over the reaction vessel and when he analyzed what was in the vessel now he actually had amino acids amino acids are compounds that form when molecules of carbon and other elements linked together they are the essential building blocks of proteins and cells vital ingredients of all living things Stan Lee Miller's experiment was headline news and jump-started the scientific search for the origins of life life is really chemistry there's no question about that in fact it's a chemistry that when you get the recipe right it goes and it goes fairly quickly that recipe is hotly debated today and most scientists think the environmental conditions on early Earth we're very different from the ones Miller simulated in his lab and another debate rages about when this recipe first got cooked up on our 24-hour clock the barrage of asteroids and comets lasted from about midnight until almost three thirty in the morning the assault then weakened but continued for more than a hundred million years it's hard to believe that life could have gained a foothold during this unstable period but new discoveries reveal that life may have existed as early as four in the morning or about 3.8 billion years ago the evidence comes from some of the oldest rocks on the planet found in the remote regions of west greenland the geology of Greenland is unique it contains a record of some of the earliest geological processes that we know of on the earth the rocks themselves are thought to be between 3.7 and 3.9 billion years in age these rocks are sold that any fossils they once contained have been destroyed so to find out if life existed when they formed moyzisch had to look for evidence that is far more elusive there may have a one time been small fossils microfossils but under the conditions of heat and pressure that these rocks experienced such fossils would have been disaggregated and destroyed so what we have left behind in our chemical fingerprints of ancient bacteria or microbes to search for those fingerprints moyzisch first extracts a sample from the ancient Greenland rocks then you will analyze its chemical composition looking for carbon a signature of life but carbon comes in several different forms and moyzisch wants to know if the carbon in this sample is the kind by living creatures if so he believes that life may have existed when these rocks formed over 3.8 billion years ago a controversial claim it was a surprise for us to find evidence of ancient life in these rocks we didn't know if who would be there you know just because the stage is set doesn't mean that the actors are present but these samples here represent the first evidence we have direct evidence of a biosphere on our planet if it emerged so early life was lucky to miss the greatest Cataclysm of all time an impact like no other in our planets history it happened when another rocky sphere about the size of Mars collided with earth the outer layers of our planet were vaporized and the debris from this collision coalesced to form the moon that impact was so powerful that any building blocks of life that existed on earth would have been destroyed this gives rise to speculation that the ingredients of life didn't form on earth at all but arrived special delivery from outer space midsize knits appearance this thing came from outer space they even have reason to believe it some home of lightning Hollywood has always been taken with the idea that life came from outer space but it's not as far-fetched as it might sound space is not very far away space is only about 20 kilometers that way now that's um that's very close and space is vast and a scientist named Don Brownlee designed an experiment to find out if space might actually harbour the building blocks of life there are 40,000 tons of bits of comets and asteroids that impact the earth every year this is mostly in form of particles are less than a millimeter in size we breathe them they're on the food that we eat but they're very difficult to fun you can only find him in very special places to see if the shower of space dust contains the ingredients for life brownlee needed to obtain samples uncontaminated by Earth's atmosphere so to get just a few micrograms of dust he commissioned a former spy plane to fly close to the edge of earth's atmosphere sticky pads on the plane's wings collected the space dust then Brownlee's colleagues sliced the dust particles into slivers less than one-tenth the thickness of a human hair and they discovered that these tiny particles are rich in the seeds of life when you look at an electron microscope this is wonderful array of minerals and carbon and organic materials that are 4.5 5 billion years old and we believe are the building blocks of life and this extraterrestrial dust isn't the only possible source of life's ingredients in a region of space called the asteroid belt are huge amounts of debris left over from the formation of the solar system and sometimes chunks of debris containing metal and rock fall to earth bearing surprising gifts one such meteorite landed in the town of murcheson Australia in 1969 it's a col- little chunk of meteorite which fell on Australia last year for the past six months they've been taking it apart and have discovered it contains amino acids of building blocks of life it was the first time if complex organic compounds had ever been found in material from space and if meteorites like it were common perhaps they had delivered vast quantities of the original constituents of life to early Earth meth organics are present here that we think that meteorites like this provide to the early Earth its entire budget of organic so all your GAX in your body all the carbon your body and in your lunch you had today arrived on the earth in meteorites like this if they come in the atmosphere and large enough objects they like little capsules coming in the atmosphere they break apart on your surface and deposit their cargo of organics more than 70 kinds of amino acids have been found in meteorites and many are the fundamental ingredients of proteins that make up living cells during the heavy bombardment millions of meteorites may have seeded the earth with the stuff of life and there might have been an even more efficient delivery system comets are like giant dirty snowballs made of ice and rock some comets that hit the early Earth were the size of mountains and a large portion of their mass could have contained organic compounds the destructive power of comets and meteors is astronomical the meteor that slammed into Earth some 50,000 years ago here in Arizona blasted a hole in the ground nearly a mile wide from here to here and so deep it could hold a 60-story skyscraper and as if that weren't enough the force of the impact was so great that it instantly vaporized nearly the entire meteor 300,000 tons of it so it makes you wonder if the building blocks of life were delivered courtesy of comets and meteors could any of the tiny ingredients they carried have survived the landing and just what happens to things like amino acids when they slam into Earth with such devastating power to answer those questions one scientist came up with an ingenious experiment using a huge gas powered gun Jennifer blanks simulates the extreme pressures and temperatures that are unleashed when a comet smashes into Earth we set out to test whether or not materials would survive or whether they would break down and we expected that we're hoping that some fraction was revived we figured the parts that didn't survive would break down into smaller components but in fact what we found was much more exciting the gun fires a bullet at 5,000 miles an hour towards a sample that represents the organic molecules inside a comet the sample consists of a solution of five different amino acids two of them present in every living cell the mixture is inserted into a steel capsule the gun will send a shockwave through the capsule simulating the extreme pressures of a comet's impact I think it's very hard to just imagine what kinds of pressures were generating these experiments if you think about going to the bottom of the ocean the pressures you'll have their only 100 times atmosphere so these are hundreds of thousands of times atmospheric pressures will Jennifer blanks experiments show that the building blocks of life can survive a crash landing on earth clear the room ok charging out hey bringing up the x-rays the unholy external group ready depart go ahead hit in three two one on fire when they remove the capsule it's undamaged but have its contents survived the impact the ones clear solution of amino acids has turned Atari brown color and the analysis revealed that not only had the material withstood the colossal pressure of the impact but it had transformed into a new compound amino acids combinations of carbon that other basic elements had fused together to form more complex molecules called peptides we went from our initial small compounds and here's an example of one of them simple amino acid and we use the energy associated with the impact to build larger molecules molecules like this this is a peptide and we show that we can use the impact energy to grow larger molecules from the simplest building blocks of life peptides linked together to form larger building blocks proteins which make up all the cells in our bodies but the leap from nonliving ingredients to a living creature complete with DNA which allows cells to replicate is staggeringly complex no one knows how this process started or what course it took it is hard to really get your head around the great leap from nonliving to living well it's hard enough that nobody's succeeded in doing it in the laboratory I think it's an astonishing mystery and one that we truly don't understand in any great detail well we don't yet know how the spark of life occurred we can try to figure out where it might have gotten a foothold and because the planet was under such devastating assault from comets and meteors the leap to life may not have taken place up here on earth surface to take hold life might have needed a safe haven perhaps underground a team of scientists descends into one of the deepest mines on earth to investigate whether microbial life can survive far below the earth's surface the mining environment gives us this fantastic window into the deep subsurface it's a unique scenario because there was nowhere else on planet earth that allows you to have access to that sort of sample location at two three three and a half kilometers deep it takes 45 minutes to reach the heart of the South African mind conditions here are extremely uncomfortable for humans that is the temperature of the rock is a hundred and twenty degrees Fahrenheit and the air pressure is twice that at Earth's surface life down here survives entirely without sunlight if they exist microbes need to find a way to live in pitch darkness drawing chemical energy from water and minerals trapped in the surrounding rocks what organisms have been shown potentially to be able to use these molecules to provide themselves of energy and support themselves completely independent of photosynthesis and if we can prove that as the case here and that's very interesting because that adds credence to the idea that you could have a life originating in the deep subsurface as the miners drill into the rock they break into ancient pockets of order havens for microorganisms we're not sure how organisms can live in such extreme environments the major thing is there's such low nutrient availability there's nothing really for these guys to continually use and process to survive and yet somehow they do and the question is how do they do the first step is to collect pristine samples of the water and see if they can grow the microbes it contains I'll get a very big sense of achievement if I can actually take something that's been isolated for 200 million years put it in the laboratory and actually find out what it is this organism needs to survive in a makeshift lab near the mine the team attempts to recreate the environment deep inside the rock and they have found that these microbes are dining on a variety of strange gases it turns out in the deep subsurface there's an abundance of methane gas and Ethan and propane that for you and I that's not a very exciting diet but what we think is that these organisms may be taking that kind of gas and actually using that as a food to survive on such an exotic diet the bacteria draw just enough energy to divide and reproduce only once every thousand years suggesting a way that life could have survived deep beneath the surface of the early Earth an earth crust may not have been the only place where life could have hidden from the heavy bombardment another safe haven may have bitten the ocean volcanic activity was intense on the early Earth chemicals from deep inside the planet spewed into the primitive seas even today marine biologists have discovered volcanic vents on the ocean floor despite scalding temperatures acid eruptions and total lack of sunlight they found creatures of all types thriving down here and at the bottom of the food chain are microbes that live on the noxious hydrogen sulfide gas erupting from the vents on early Earth primitive life may have survived in similar environments if all of the bombardment was occurring near the surface survivors would be existing in just these kinds of hydrothermal vent communities where there's abundant water and nutrients and heat and food in the form of chemical energy it has been found that organisms collected there nowadays are genetically kin to some of the earliest organisms that we think existed on the earth by about three and a half billion years ago were five o'clock in the morning on our 24-hour o'clock the bombardment of asteroids and comets had ceased with far fewer violent impacts on earth microbial life could now survive outside its protective hiding places after it reaches Earth's surface life would take advantage of another source of energy the Sun up here microbes evolved a green pigment known as chlorophyll this allow them to trap sunlight and use it to drive a chemical reaction that converts carbon dioxide and water into food called photosynthesis it was a clever invention that enabled some bacteria to grow and reproduce almost without limit once it started photosynthesis was a runaway success and today it's how all green plants make their living as earth cooled this new generation of cells spread across the oceans immense colonies of green slime would take over the world kicking off the greatest transformation in our planet's history photosynthesis is the great liberator of biology with photosynthesis the energy is coming from the Sun and life could spread literally over the entire planetary surface and this remote corner of Western Australia holds clues to how that happened these domed structures called stromatolites are built up layer by layer over thousands of years by tiny microbes these microbes may be similar to life-forms that dominated our planet billions of years earlier and in the arid Hills nearby there may be evidence of these ancient creatures these rocks have remained unchanged for three and a half billion years here it's possible to walk on the surface of early Earth Martin bank anandan spends months at a time in this wilderness studying the geology and producing maps in a secret location in these hills is what could be one of the greatest geological discoveries of all time these are the oldest fossils in the world at about three and a half billion years old and they're composed of stromatolites and at this outcrop we can see two different types of structures that these creatures formed first are these black mats that have wrinkly textures all through it and the second are these larger domes but form these broad structures the most likely way these things formed is by the growth of microbes like modern stromatolites these ancient structures could also have been built by colonies of bacteria and not far away or fossilized ripple marks which suggests they might have grown in shallow water and here you can see we've got a smaller structure that we call the Mickey Mouse ears which is this beautiful doubly branching structure and there's nothing else that we can think of which would make that except something that was growing on the bottom of the ocean so perhaps the ancient stromatolites were formed by microbes like the ones that build these structures today these big stromatolites are composed mostly of rock at the bottom and the only living part of the stromatolite is a thin layer on top and that thin layer on top is made up of microscopic Bluegreen bacteria called cyanobacteria named after the blue-green color of their cells these cyanobacteria use photosynthesis to collect energy from the Sun they secrete a sticky coating to shield them from ultraviolet radiation as tiny pieces of dust and sediments settle on top of the sticky cells the bacteria migrate closer to the surface to reach the light the layers of sediment build-up by about a half a millimeter a year these structures contain living microbes just as they have for thousands of years amazing thing about these stromatolites is that the microorganisms which build them are so tiny and the structures that you see around me compared to their size are enormous it'd be like if humans made a skyscraper that was 105 kilometers high by 70 kilometers across these are massive structures for the size of the organisms that make them many different shapes and sizes of what appear to be fossilized stromatolites have been found in the rock it seems likely that these structures were formed by some type of microbe living on the early Earth perhaps even by the ancestors of today's cyanobacteria we're looking at sort of a cross-section through the top of these cones and the layers that were laid down year after year and the fact that they're all different sizes on this one surface shows that there was a colony of microorganisms growing on this one bedding plane and that's really fascinating because it means that life evolved on this planet very early and very fast and it's the cyanobacteria that would bring about the most astounding change in Earth's history a change that could have started as early as three and a half billion years ago over time stromatolites would spread out across the planet as a byproduct of photosynthesis the ancient bacteria produced a waste gas oxygen the oxygen was absorbed into the oceans at first they're combined with iron erupting from undersea volcanoes to form iron oxide particles that fell to the ocean floor over the next several hundred million years the planet literally rusted they may have been other forces at work but eventually all the iron was turned into oxide building a layer after layer one of the most valuable mineral deposits on earth iron ore located in western australia this is one of the world's largest iron mines the iron here was originally deposited on the floor of a primordial ocean at the foreign position stall disconnected far in 10 seconds with a five-second get there are the five day every week the excavator half a million tons of iron ore used to make steel for everything from cars to skyscrapers third one in a more pristine state thousands of ancient layers of iron ore are preserved in the karijini gorge just 30 miles from the mine the layers exist because different amounts of iron oxide were deposited at different times of the year cyanobacteria produced oxygen in varying amounts as water temperature changed with the seasons all over the world vast amounts of iron ore were laid down in similar ways on our day-long clock this process continued until one in the afternoon eventually oxygen produced by cyanobacteria began to build up in the atmosphere slowly but surely this transformed the planet over the next eight hours or so tiny microbes raised the level of oxygen from less than one percent to today's twenty one percent the time was about 9 p.m. it's amazing to contemplate but without cyanobacteria they would be no oxygen and earth would still be smothered in noxious gases plants animals and humans would have never evolved we're sitting here today breathing an oxygen-rich mixture of air we couldn't be here without that oxygen but that oxygen wasn't present on the early Earth and it only became present because of the activity of photosynthetic organisms life has made this environment what we know it's allowed us to live on the surface it allows us to breathe it allows large organisms like we are to function at very high rates of activity the oxygen also help protect life from the sun's lethal ultraviolet radiation by creating a layer of ozone in the upper atmosphere one of the fascinating properties of that is that it actually screens out just sort of like a sunscreen does on your skin screens at this harmful radiation with the protection of the ozone layer life was able to diversify into more complex organisms it took only the last three hours of the day for all other life forms on our planet to evolve the first multicellular life emerged at six minutes past nine in the evening then came fish and insects and reptiles by about ten minutes to eleven in the evening dinosaurs roamed the earth the first primates appeared at 22 midnight and with less than 30 seconds to go the first humans made their appearance it's only been the last know ten percent of the Earth's history where there was life on the surface of of the earth that you would see with your naked eye so for most of Earth's history life has basically been invisible on your over a billion or two billion years the amount of oxygen that these little creatures produced was enough to actually change the entire atmosphere of the planet multicellular life that were most familiar with animals plants near environment was made possible by the slow toilsome task of bacteria to oxygenate the atmosphere microbes ruled the earth for more in 3 billion years two-thirds of its history these tiny organisms had transformed an entire planet without them complex life humans included would have never evolved the origin series continues on line on Nova's website explore the arguments for and against intelligent life in the Milky Way galaxy then cast your vote find it on pbs.org to order this program on VHS or DVD or the book origins 14 billion years of cosmic evolution please call one eight hundred 255 9424 Nova is a production of WGBH Boston original funding for this program was provided by the Park foundation dedicated to education and quality television and by Sprint and Microsoft major funding for origins is provided by the national science foundation America's investment in the future additional funding is provided by nasa office of space science the Alfred P sloan foundation to enhance public understanding of science and technology and the george d smith fund major funding for Nova is also provided by the Corporation for Public Broadcasting and by PBS viewers like you thank you I am PBS