What Would The Earth Be Like Without Photosynthesis?

in the wilds of upstate new york the catskill mountains dominate the western horizon they are cloaked in green maple ash and oak stand shoulder to shoulder in dense forests that drape across the hillsides and at the mountain's feet a small clearing is little more than a gray scar in the flesh of this verdant landscape but this scar is a tiny window on another time on another long lost forest [Music] the clearing is a sandstone quarry once the source of building stone for the nearby towns all stand silent now abandoned save the birdsong and the rustling leaves today used for little more than off-road vehicle stunts but in 2019 paleontologists made an extraordinary discovery [Music] etched into the flat quarry floor is an intricate radial structure branching out from a single central point dendritic arms extend for many meters at first glance it seems as though lightning has struck the grey rock scorching its forked pattern into stone itself but this is no lightning strike they are the fossilized roots of immense and unimaginably ancient trees [Music] here tucked beneath the roots of the modern day catskill forest are the roots of the very first forest on earth [Music] the rocks that contain these remarkable fossils are an astonishing 385ml years old [Music] dating to the late devonian period [Music] and during that primordial epoch large animal life was still largely confined to the oceans [Music] the land surfaces however are overrun with green plants and primitive insects that crawl burrow and flutter amongst the foliage on this green new world for the very first time a battle for vegetal dominance drives plants to ever greater heights they are desperate for the life-giving light of the sun [Music] but in constant conflict with their neighbors always threatening to cast them into shadow [Music] it was this eternal arms race that gave rise to the very first trees we know them as archaeopterus different from the ones we know today but not so different to be [Music] unrecognizable with woody roots and branches they evolved to stand proudly up to 10 meters tall breaking free of the jumbled green battleground of horsetails and ferns beneath they were the giants of this world [Music] and so the quarry floor the foot of the catskill mountains preserves some of the earliest days of the age of trees [Music] the fossil roots are those of archeopterius reaching out probing for water in elite devonian soil as no plants had done before [Music] in the hundreds of millions of years since time has turned the ancient forest floor to stone yet nevertheless those first trees have left their mark here just as they left their mark on our [Music] world [Music] once this evolutionary arms race for light had led to trees some 385 million years ago they proved to be an especially successful adaptation soon spreading to every corner of the world and in fact it was a perfect time in earth's history for colonization and expansion the perennial forces of continental drift having brought the disparate land masses together to forge a single supercontinent pangaea [Music] where they collided continental puzzle pieces crumpled at the edges lifting great mountain chains into existence the catskills themselves an extension of the appalachians already loomed over the landscapes as the earliest forests spread from pole to pole it was a warm wet time with high sea levels drowning shorelines creating shallow seas and vast tracks of swampy land this was the setting in which the first forests found their feet innovated and succeeded huge trees grow up to 35 metres tall reproducing with spores like ferns do today at their feet the understory still bustled with hardy colonizers leggy horsetails bristled wherever the dappled light breached through to the forest floor trees and plants put down roots probing deep into the ground in search of water and anchorage through biological action the land surface was shattered weathered more than ever [Music] before the dominion of trees also set the stage for animal life to finally make its decisive move onto land [Music] tetrapods took their first tentative steps out of the ocean overshadowed by the trees that had already made it their home insects thrived in this verdant playground diversifying into new and bizarre forms specialized for living among the many in various types of plant they rely on for food and shelter in an increasingly vertical ecosystem flight becomes a new necessity and the insects spread their wings with the vast supercontinent covered by forest the photosynthetic engine is pumping at full speed drawing in carbon dioxide from the atmosphere and replacing it with oxygen this reactive gas is no longer poisonous to life on earth it's been a constant companion for one and a half billion years and life is now utterly reliant on it [Music] and as the global forests thrived oxygen levels soared to levels 50 percent higher than today with excess oxygen in the air oxygen breathers thrive too giant insects dragonflies and centipedes far larger than today now fluttered and crawled through the endless forest swamps [Music] for 60 million years trees ruled the earth their dominion is immortalized in the name of an entire geological period the carboniferous so named for the huge swathes of carbon-bearing rock left behind when the great forests died [Music] rocks that fuel our world today and all of this was made possible by photosynthesis using light as energy an unexpected chemical innovation deep in life's microbial past but just how much of our modern world is shaped by photosynthesis and what might the planet look like had it never evolved at all [Music] some hundred or more light years away from earth a rocky planet orbits a yellow star [Music] on it intelligent life has evolved [Music] great civilizations have risen collapsed and risen again spawning immense advances in culture arts society and increasingly [Music] technology they surround themselves with technology [Music] and as they strive to understand themselves naturally they seek an understanding of their place in the universe [Music] at the very height of their technological revolution they build elaborate scientific instruments launching them on rockets into orbit around their star [Music] these alien telescopes position themselves in the shadow of the home planet shielding themselves from the glow of the star allowing an unpolluted view of the night sky [Music] with unprecedented precision the telescopes examine the light from each distant sun looking for a characteristic dip in brightness which portrays another planet another solar system just like their own [Music] but their instruments can see far more than that as a planet passes in front of its sun some of the starlight will pass through the tiny sliver of atmosphere at the planet's edge [Music] by analyzing the spectrum of visible and infrared light from that sliver these curious scientists can reconstruct the composition of distant atmospheres [Music] so as they train their telescopes and our sun another yellow star like their own they are confronted with a planet a world which dims the star every 365 days in its sliver of atmosphere they see nitrogen water vapor a little carbon dioxide and oxygen [Laughter] [Music] the discovery doesn't just make the extraterrestrial news its reverberations alter the very course of their history [Music] for life has been discovered beyond their solar system [Music] they are not alone [Music] for these aliens know the significance of oxygen in an atmosphere such a reactive gas can't linger in any great quantity unless it's been constantly refreshed and they know no other way of generating oxygen than life itself [Music] no inanimate planetary process could be responsible only the process of photosynthesis is able to make so much oxygen so reliably [Music] using light to split carbon dioxide and water to capture energy for life [Music] even from trillions of kilometers away this planet our planet screams photosynthesis and life our entire atmosphere seen from space is a product of plant life whether this is intelligent or not remains to be seen if an interstellar expedition were to be launched from this hypothetical alien world no matter how long it would take scientists on board or reading the data from home would be able to confirm their theories as soon as they were close enough to take a picture of the planet just a few pixels would reveal that in addition to the blue and white of a watery world the earth is trimmed with green compared with the other lifeless worlds of our solar system coloured red gray or white by the rocks and ice exposed at the surface the earth is swaddled with life and that life is green and on earth that green has been a fundamental part of our history during the early 14th century genuine's mapmaker pietro vesconti made a name for himself in the maritime city-state of venice [Music] creating maps of the mediterranean and black seas his nautical charts were among the most advanced and accurate of the day using compass bearings and sailing directions from ports and harbours to precisely reconstruct the shape of the coastline [Music] so in 1321 when approached by a venetian statesman to produce maps for a new manuscript he knew that something special was called for [Music] this manuscript would be used to encourage a new crusade to the holy land as ever war being the great motivator for our species not only did these maps need to be accurate but they needed to be beautiful and compelling too visconti spared no expense and so it is visconti's mapamondai his map of the medieval european world that impresses with its vivid green coloration to this day it is unique for the time in its accuracy and its realism one of the most impressive early attempts to define the borders and contours of our world [Music] subsequent map makers have copied the shape of the world onto paper pouring carefully over the shape of kingdoms and continents but unwaveringly the colors remain the same blue for the oceans green for land green is the color of photosynthesis and it's become the colour of the land too it's the colour we as humans instinctively link to nature to healthy growing landscapes [Music] it's the green pigment in plants that powers photosynthesis and it's photosynthesis that powers all life on earth but photosynthesis powers even more than life it powers industry too since its emergence in single-celled bacteria more than two billion years ago photosynthesis has transformed not only the surface of the planet but also the rocks that form underground the oxygen pumped into the atmosphere rusted the proterozoic land surface turning sediments red and producing brand new oxidized minerals never before seen on the planet and as photosynthesizing plants came into their own the sheer quantity of organic carbon captured began to leave its mark ordinarily plants that die are recycled as part of the great circle of life animals insects and microbes go to work stripping energy-rich organic molecules from a vegetable carcass but sometimes conditions conspire to spare a dead tree plant or algal bloom from the scavengers perhaps they are swept away in a flood or buried by a sudden volcanic ash fall or drop through the ocean depths to anoxic waters where no life can survive if plant life is buried undecayed then its carbon is committed to the rocks time heat and pressure transform it and tectonic movements may eventually bring it back to the surface about 50 million years ago the same tectonic forces that pushed up the alps to the south also uplifted layers of carboniferous carbon-bearing rocks in the middle of england subsequent erosion exposed the thickest coal seam in europe that turned the very ground black across an area of about 36 000 hectares this became known as the black country and in the late 18th century it was the very epicenter of the industrial revolution many consider the boundaries of the black country to be defined exclusively by where the 30-foot coal seam breached the surface certainly it was the abundance and accessibility of the coal here that secured the black country's importance in the growing industrial world visitors would come to describe the region as black by day and read by night as every scrap of land was claimed for collieries furnaces foundries and factories chimneys belched smoke through the night and a spectacular new industrial future dawned this was where the first successful steam engine was built where the first bridge made entirely of iron was constructed the black country transformed britain into the world's furnace the industrial revolution was the beginning of a new era for humankind the industrialization of our world paved the way for mass production and the technological advancements at a terrifying pace none of this would have been possible without subterranean coal and other fossil fuel deposits worldwide and none of those deposits would even exist without plants their crushed ancient remains fueling the furnaces of industry it was the invention of photosynthesis in bacteria billions of years ago that made our modern technological lives possible from the composition of the land and sky to the staggering diversity and achievements of life photosynthesis has utterly completely transformed the earth a single chemical reaction involving mere atoms and electrons became so successful that it was written large over billions of years and eventually had the power to modify an entire planet but what would the earth look like if this unique biological engine had never arisen [Music] evolution is blind new innovations arise by chance and if they help an organism succeed they will persist into future generations photosynthesis was just one such chance innovation and a different role of the evolutionary dice could have plotted a very different future for our planet and the life that grew here a world without photosynthesis would be a world without technology without industry without green on the land and in the sea without oxygen in the atmosphere and almost certainly without humanity to try and understand it all without photosynthesis to precipitate the great oxygenation event more than two billion years ago the archaean oceans and atmosphere would persist just as they had already persisted for billions of years before levels of carbon dioxide and methane in the atmosphere would stay high continuing to swaddle the earth in a thick insulating blanket of greenhouse gases [Music] icy poles and mountain peaks would become a thing of the past as the temperature of the entire planet crept up and this would be a roiling humid heat as water vapor drawn from vast world spanning oceans fed towering thunderclouds storms would rage around the planet's circumference whipped into swirling cyclones that feed on the hot surface waters and hurl their energies at those barren land surfaces that have the misfortune to lie in their path [Music] as millions of years pass this heating only worsens the faint young sun once barely burning hot enough to keep the planet's ocean's liquid has begun to mature nuclear fusion in its core builds up heat and the warmth that the earth receives from its nearest star inches up year on year with a thick atmospheric blanket of carbon dioxide methane and water vapor this added heat is swallowed and kept close earth teeters on the edge of the runaway greenhouse warming that baked its neighbor venus to death but our world lies some 40 million kilometers further from the sun it retains its oceans and the planet's hot core churns on oblivious to the heating on the surface volcanoes erupt tectonic plates shuffle and life clings on in the archaean oceans life survived quite happily before the invention of photosynthesis instead of feasting on the sun's energy these chemosynthetic bacteria turn their attentions to the ground and the mineral energy contained within had this remained the only option for life then two billion years of evolution would produce a very different biosphere to the one we now inhabit in 1986 when communist surveyors in the southeastern corner of romania began investigating a potential building site for a new power plant they made an extraordinary discovery as they measured the strength of the gravity across the flat featureless planes their instruments spoke of a massive void several meters below the surface that quite simply shouldn't have been there [Music] the ground was unbroken hiding any indication of a cave beneath but as they tunneled vertically down they found a vast clay-lined cavern system that extended hundreds of meters into the pitch darkness these caves had been shut off from the outside world for more than five million years without a glimmer of light to penetrate the gloom and yet in the total subterranean darkness life thrived small blind insects and other invertebrates crawled slithered and swam through the black pools busying themselves with the basic motions of existence survival reproduction and finding food the nutrition at the base of all food chains in this isolated cave was not created with the energy of the sun but rather the energy of the earth itself microbial chemosynthesizers not so far removed from their archaean cousins seized every opportunity to feast on whatever chemical energy they could find sulfur compounds methane and ammonium became potent inorganic energy sources for these resourceful bacteria they colonized the water's surface in thick films or cling to the cave walls and ceilings held together by sticky extracellular glue and by transforming their mineral food sources they capture the energy they need and expel their waste products to accumulate in the airtight cavern here carbon dioxide levels soar to 100 times the concentration of the air outside the air smells of rotten eggs and burned rubber and the water sizzles with sulfuric acid but to the chemosynthesizers and the animals that eat them this is the only home they've ever known this pitch-black poisonous cave in romania is a tiny window into a world without photosynthesis in an alternate present where bacteria never learned to eat the sun they instead become breathtakingly proficient at eating the earth so from their modest beginnings around volcanic vents in the deep ocean chemosynthetic microbes spread and evolve learning to survive off the meager pickings of less energetic minerals with the help of their extracellular glue and their waste products microbial forms begin to shape the world both beneath the ocean surface and on land [Music] waste sulfuric acid eats away at the ground carving out huge gorgeous and plunging cave systems in all but the most resistant of rocks chemosynthesizers relish in the new rock surfaces exposed by the chemical corrosion and follow the water and mineral food into the depths of the crust instead of vertical forests of trees reaching for the skies there would be plunging dark forests of microbial stalactites in fractal biological caves light or dark these microbes do not care as long as there is fresh chemistry within reach and yet the chemical energy in the earth is limited minerals run out and waste products accumulate until these chemical factories are starved and smothered into submission food chains and ecosystems of more complex life could evolve to rely on the chemosynthesizers but since the energy is limited the abundance and complexity of these higher forms is also curtailed they are smaller slower and less abundant than the animals we share our photosynthetic ecosystem with [Music] and there are no mighty apex predators or sentient sapient equivalents only grazers crawling among the weeds of a slimy colorless chemosynthetic world indeed this is a diminished existence over two billion years ago a roll of the evolutionary dice gave us photosynthesis a different role could have secured a very different fate for the planet and for life but these dice are weighted many researchers believe that photosynthesis is inevitable on a world like our own just as it is on an alien world given the same chemical circumstances [Music] although life can use the bounty of a planet to power its biological engines the mere fact that this fuel is exhaustible destined to run out someday means that there is a very real pressure to seek out an alternative and like the pre-photosynthetic bacterium of the archaea in the world for us today sunlight is the ideal alternative [Music] readily and endlessly available on the surface of every terrestrial planet [Music] on our world and on others like it finding a way to use that light might be the only way for life to survive in the long run at all and searching for the signs of photosynthesis on a planet oxygen in an atmosphere or a smear of green across the land or carbon locked away in its rocks may be the best way we can hope to find life elsewhere in the universe [Music] you've been watching the entire history of the earth don't forget to like and subscribe and let us know what you think in the [Music] comments [Music] our writer leila batterson has released a video to coincide with this one investigating the detection of oxygen in alien atmospheres by the james webb space telescope check it out here or in the link below

Channel: History of the Earth

Views: 134,687

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Id: Cz-b-b0sNkg

Length: 35min 1sec (2101 seconds)

Published: Sun Jan 31 2021