The Complete History of Earth’s First Plants — Full Documentary

[00:00:00] Speaker 1: The earth we know today, covered in forests, grasslands, and jungles, was not always green. For billions of years, the continents were vast stretches of bare rock, sand, and dust. There were no forests and no grasslands, there were no roots to hold the soil in place, and no leaves to cover the landscape. Rain struck the stone directly, the wind swept across miles without meeting any obstacle, and nearly all life remained confined to the water, until something tiny began to change everything. About 500 million years ago, the ancestors of plants began to leave the water and spread across dry land, where almost nothing could survive. At first, they rose only a few centimeters above the ground. But those small organisms did something that would end up transforming the entire planet. They helped create soils, altered the atmosphere, opened new ecosystems, and prepared the way for animals to follow them. Dear Time Traveler, today we are going to journey through one of the greatest conquests in the history of life. From the bacteria that learned to capture the energy of the sun, to the first algae, the tiny plants of the Ordovician, the first forests, and finally, the appearance of flowers. Because before animals came to dominate dry land, someone had to turn it into a place where life was possible. And it was the plants that arrived first. Before we begin, tell us in the comments what other evolution of a species or group of animals you would like us to explore in an upcoming episode. And if you want to keep discovering how the world we know today was born, subscribe to the channel and join us on this journey through the history of plants. The history of plants begins long before there was anything we could recognize as a plant. It begins with the cyanobacteria, microorganisms that appeared in the oceans at least two and a half billion years ago and did something no organism had ever done before. They learned to use sunlight to make their own food from water and carbon dioxide, releasing oxygen as a by-product. What we now call oxygenic photosynthesis. Cyanobacteria were not plants. They were bacteria, prokaryotic organisms with no defined cell nucleus, no membrane-bound organelles, and none of the complexity we associate with the cells of animals or plants. But they invented the biochemical mechanism that would make everything that followed possible. The ability to capture the energy of the sun and convert it into organic matter. Before cyanobacteria, life depended on chemical sources of energy, such as the sulfur and iron compounds that poured from the hydrothermal vents of the ocean floor. After cyanobacteria, life could feed directly on the sun. It was the most important energy revolution in the history of biology. But photosynthesis had a side effect that, for a long time, did more harm than good. Oxygen. For the organisms that existed before cyanobacteria, oxygen was a poison. It oxidized their membranes, damaged their DNA, and destroyed the enzymes they needed to function. When cyanobacteria began releasing oxygen into the ocean, they triggered what geochemists call the Great Oxidation Event, about 2,400,000,000 years ago. A rise in atmospheric oxygen that poisoned most of the planet's anaerobic organisms and caused a mass extinction that was probably the most devastating in the history of life. Although it occurred on a microscopic scale that left none of the spectacular fossils of later extinctions. Cyanobacteria saved the world by creating the conditions for complex life, but they did so by first destroying the world that existed before them. Cyanobacteria also built the first biological structures visible to the naked eye. Stramatolites, those mounds of rock formed by successive layers of sediment trapped and cemented by microbial communities. Stramatolites were the reefs of the Precambrian world, the only structures of biological origin that rose above the seafloor for more than 2 billion years. Today, living stramatolites survive in only a few places around the world, such as Shark Bay in Western Australia, where high salinity prevents the animals that would normally devour them from living there. But a billion years ago, they lined the coasts of every continent. Cyanobacteria did more than invent photosynthesis. They became part of other cells. About one and a half billion years ago, a eukaryotic cell - a cell with a defined nucleus - engulfed a cyanobacterium, but instead of digesting it, kept it alive inside. The cyanobacterium continued to carry out photosynthesis within the host cell, providing it with sugars and oxygen in exchange for protection and nutrients. Over time, that captive cyanobacterium lost its independence and became a permanent organelle of the host cell - the chloroplast. This event, known as primary endosymbiosis, is the origin of all algae and all plants that exist today. Every chloroplast in every leaf of every plant on the planet is the direct descendant of a cyanobacterium that was captured more than a billion years ago. When you look at a green leaf, you are seeing the result of a biological abduction that changed the history of life. After the endosymbiosis that created chloroplasts, eukaryotic algae diversified across the oceans of the Neoproterozoic and the early Paleozoic into a variety of forms that included microscopic single-celled algae, filamentous algae that formed mats over the rocks of the seafloor, and larger multicellular algae that grew in shallow coastal zones. Green algae, the group that would eventually give rise to land plants, were particularly abundant in fresh waters and in the transition zones between sea and lands. Coastal pools, estuaries, river banks, and the rain puddles that formed in the intertidal zones. It was precisely those transitional habitats that set the stage for the colonization of dry land. The algae living in coastal pools regularly experienced periods of desiccation. The tide went out, the water evaporated, and the algae were left exposed to the air for hours or days before the next rain or the next tide submerged them again. Those that could tolerate this temporary drying survived. Those that could not, died. And over millions of years of natural selection, the algae of the coastal pools gradually developed adaptations that protected them from dryness, waxy cuticles that reduced water loss through evaporation, thicker cell walls that held the structure of the cells together when the water withdrew, and biochemical mechanisms that allowed them to repair the damage caused by direct exposure to ultraviolet radiation. Molecular genetic analyses have revealed that the group of green algae most closely related to land plants is the carophytes, a group of freshwater algae that today includes the well-known stoneworts, those branching aquatic plants that look like underwater versions of horsetails. Carophytes share with land plants a series of biochemical and genetic features found in no other group of soils of algae, specific enzymes for the synthesis of the cell wall, hormone-signaling proteins that regulate growth, and genes related to tolerance of desiccation. This indicates that the adaptations that made the colonization of land possible did not appear all at once but accumulated gradually in the lineage of freshwater algae over hundreds of millions of years, long before any plant set foot on dry land. The final leap, the transition from a freshwater alga to a land plant, took place approximately 470 million years ago during the Ordovician. The oldest evidence of land plants comes from fossil spores found in rocks of the Middle Ordovician in Saudi Arabia, Argentina, and the Czech Republic. These spores, which are preserved in groups of four, a pattern called a tetrad that is characteristic of land plants, show that the first plants were already reproducing on the land surface almost 500 million years ago, even though their vegetative bodies, probably too fragile to fossilize, have not been preserved. The first land plants looked much more like today's mosses and liverworts than like any tree or shrub you might imagine. They were small, only a few centimeters tall, with no true roots, no woody stems, and no leaves in the modern sense of the word. They clung to the ground by means of simple structures called rhizoids, cellular filaments that anchored the plant to rock or substrate, and could not absorb water and nutrients from the soil as efficiently as true roots. They depended on absorbing water directly through their entire surface, which confined them to the wettest habitats: riverbanks, lake margins, the splash zones of waterfalls, and soils permanently soaked by rain. But even these tiny and seemingly fragile plants transformed the world. By establishing themselves on bare rock, the first land plants set in motion a process that would create something that had never existed before on the surface of the earth. Soil. The primitive roots and rhizoids of the first plants produced organic acids that slowly dissolved the surface of the rock, releasing minerals that mixed with the dead organic matter of the plants themselves to form a layer of fertile substrate where new plants could germinate. Before plants, there was no soil. Rock was rock. After plants, rock began to turn, centimeter by centimeter, into earth. The first land plant with a vegetative body preserved in the fossil record is Cooksonia, a tiny organism that appeared at the end of the Silurian about 425 million years ago. Cooksonia stood only a few centimeters tall and consisted of dichotomous stems, that is, stems that branched repeatedly into two equal limbs, each ending in a small spherical capsule called a sporangium, where the reproductive spores were produced. It had no leaves, no roots, and no flowers. It was, in essence, a forked green stem ending in little balls of spores. But Cooksonia had something that earlier plants did not possess: vascular tissue. For the first time, a land plant had developed an internal system of conduits that carried water from the base to the tip of the stem, allowing it to grow upward without depending on the direct absorption of water across its entire surface. Vascular tissue was the innovation that changed everything. Without vascular tissue, a land plant is limited to a few centimeters in height because it cannot transport water over a greater distance than capillary action and diffusion allow. With vascular tissue, that limitation disappears. Water can be pumped from the roots to the tips of the branches at heights that would eventually reach 100 meters in today's redwoods. Vascular tissue freed plants from the tyranny of wet ground and allowed them to grow upward toward the light, competing with one another for access to the solar radiation that fueled their photosynthesis. And that competition for light, that vertical race that began with the few centimeters of Cooksonia, would produce, in barely 100 million years, the first forests on the planet. Alongside Cooksonia lived other primitive vascular plants that paleobotanists have grouped under the informal name of rheniophytes, after the Rhine site in Scotland, where some of the most extraordinary plant fossils in the world have been found. The Rhine Chirt, a siliceous rock about 410 million years old, preserved an entire terrestrial ecosystem in cellular detail that is almost miraculous. The plants of the Rhine Chirt, such as Aglaophyton and Rhinea, are preserved with their individual cells perfectly visible, which has allowed scientists to study their internal anatomy at a level of detail that is normally possible only in living organisms. And what those studies have revealed is extraordinary. The plants of Rhine already had symbiotic relationships with mycorrhizal fungi, exactly the same kind of plant fungus association that today allows the vast majority of land plants to absorb nutrients from the soil efficiently. The alliance between plants and fungi was not a a very small later invention. It existed from the very first moment plants began to colonize the land. In barely 70 million years after the appearance of Cooksonia, land plants achieved something that would have seemed impossible when viewed from the coastal pools of the Silurian. They created the first forests on the planet. The Devonian, the period that extends from 419 to 358 million years ago, was the age in which terrestrial vegetation went from being a low carpet of plants only a few centimeters tall to becoming a forest canopy tens of meters high that covered vast stretches of the continents. It was the fastest and most radical transformation the surface of the Earth has undergone in its entire history. To grow upward, plants had to solve three fundamental problems. The first was structural support. A soft stem cannot hold up a column of plant tissue several meters tall without collapsing under its own weight. The solution was lignin, a complex organic polymer that plants began to deposit in the walls of their vascular cells during the Devonian, hardening them into what we know as wood. Lignin is the reason trees are hard. It is the reason wood floats, resists, and can bear enormous loads. And its appearance in the Devonian was one of the most important biological inventions. The second problem was roots. The first vascular plants had no true roots, only shallow rhizoids that anchored them to the rock. But to support a trunk several meters tall, a plant needs a much deeper and far more efficient anchoring system. During the Devonian, plants developed the first true roots, structures that penetrated deep into the substrate, branching out to cover a volume of soil large enough to support a tree. Roots did not only anchor the plant. They also absorbed water and minerals from the soil. And as they grew through the cracks in the rock, they broke it apart mechanically and chemically, accelerating the formation of soil at a rate that purely physical processes could never have matched. The third problem was leaves. The first vascular plants did not have leaves in the modern sense. Their green stems carried out photosynthesis directly, but the surface available for capturing sunlight was very limited. During the Devonian, two types of leaves evolved independently: Microphylls, small leaves without branching veins, appeared in the Lycophytes, a group of plants that would come to dominate the forests of the Carboniferous. And Megophylls, the large leaves with complex venation that we associate with most modern plants, evolved in the ferns and in the ancestors of seed plants. The appearance of Megophylls multiplied the photosynthetic surface of plants by an enormous factor, allowing them to capture far more solar energy and grow faster than ever before. The first true tree of which we have evidence was Watiza, discovered at the Gilboa site in the state of New York, and dated to about 385 million years ago in the Middle Devonian. Watiza was an arborescent lycophyte that reached 8 meters in height, with a columnar trunk and a crown of branching limbs at the top. It was not a tree like the ones we know today. It had no true leaves in the modern sense, and its crown was formed by branching structures that functioned as photosynthetic surfaces, but it was a tree. A woody, upright organism, several meters tall, with a trunk that supported its own weight, and a root system that anchored it to the ground. The forests of Watiza that existed in what is now New York 385 million years ago, are the oldest forests known. But the true revolutionary of the late Devonian was Archaeopterus, a plant that deserves to be recognized as one of the most important organisms in the history of life. Archaeopterus reached 30 meters in height and possessed a thick, woody trunk with a broad crown of branches covered in wide, flat leaves. It was the first tree with true leaves similar to those of modern trees, and the first to form dense forests that covered vast stretches of the continents of the late Devonian. Its roots were deep and branching, penetrating a meter or more into the ground and breaking up the rock at depth. And those roots had an effect that transformed the climate of the planet. By accelerating the weathering of silicate rocks, the roots of Archaeopterus drew carbon dioxide out of the atmosphere at a rate that significantly reduced the global greenhouse effect, contributing to the cooling that would culminate in the glaciations of the Carboniferous and the Permian. The first forests did not only change the appearance of the land, they changed its climate. The forests of the late Devonian also had a profound impact on the oceans, an effect that paleontologists call the land-sea connection. The roots of Archaeopterus and its contemporaries broke up rocks and released nutrients, especially phosphorus, which were carried by rivers to the sea. That flow of nutrients fertilized coastal waters, triggering massive blooms of algae and phytoplankton that consumed dissolved oxygen as they decomposed. The result was extensive anoxic zones in the shallow seas, areas of water with so little oxygen that most marine animals could not survive in them. Some paleontologists have proposed that this process contributed to the late Devonian extinctions, a pair of mass extinction events that wiped out a significant proportion of marine life, including armored plecoderms such as Dunkleosteus. It is an extraordinary causal chain. The roots of trees on dry land brought about the mass death of animals in the ocean. Plants, in conquering the land, did not only transform the continental surface. They also transformed the seas that surrounded it, hundreds or thousands of kilometers away from the nearest forest. The ecological consequences of the first forests were equally profound. For the first time, a three-dimensional habitat existed on dry land. Forests created shade, humidity, and microclimates that allowed land animals, which until then had been small arthropods confined to the humid coastal zones, to move inland and diversify into a variety of different forms that included the first flying insects, the first predatory arachnids, and the first land vertebrates, the early tetrapods that came out of the water at the end of the Devonian. Without forests, animals would never have colonized the interior of the continents. Plants came first, created the habitat, and animals followed. If the Devonian was the age when plants invented forests, the Carboniferous was the age when forests took over the planet. And the forests of the Carboniferous, which stretched from 358 to 299 million years ago, were the most extraordinary, the densest, and the most productive that the Earth has ever seen. So productive that the organic matter they produced, which accumulated in the swampy soils of those forests over millions of years eventually turned into the coal deposits that fueled the industrial revolution 300 million years later. The name of the period, Carboniferous, literally means "coal-bearing". The dominant trees of the Carboniferous forests were not trees in the modern sense. They were arborescent lycophytes, giant relatives of the tiny club mosses that today grow as understory plants only a few centimeters tall. Lepidodendron, the best known, reached 35 meters in height and 1 meter in diameter at the base of the trunk. But its trunk was not like that of an oak or a pine. It was a column of extraordinarily thick bark, marked with a pattern of diamond-shaped scars left by the leaves as they fell, and with an interior that was mostly erenchyma, a spongy tissue filled with air that provided support at minimal weight. Lepidodendron grew rapidly, perhaps reaching its maximum height in only 10 or 15 years, and reproduced by means of spores released from cone-shaped structures in the crown, like a pine cone but the size of a soccer ball. It was a life strategy radically different from that of modern trees: grow fast, reproduce early, and die young. Sigillaria, another arborescent lycophyte, was slightly shorter than Lepidodendron but had a sturdier trunk, with leaf scars arranged in vertical rows instead of the diamond pattern of Lepidodendron. Calamites, a giant horsetail related to today's horsetails, reached 20 meters in height, with a trunk divided into segments and branches arranged in regular whorls that gave it the look of a natural candelabrum. And the tree ferns, such as Saronius, formed an intermediate layer of the forest, growing beneath the canopy of the giant lycophytes and providing an understory structure that created habitats for the smaller animals of the ecosystem. The forests of the Carboniferous grew in swamps. The coastal plains of the Carboniferous continents, which were gathered in the early stages of the formation of Pangaea, were vast expanses of low, flooded terrain, where standing water created anoxic conditions in the soil. And that anoxia was the key to the formation of coal. In a normal forest, when a tree dies and falls to the ground, fungi and bacteria break it down, returning the carbon to the atmosphere in the form of carbon dioxide. But in the swamps of the Carboniferous, the stagnant water and the lack of oxygen prevented microorganisms from breaking down the wood effectively. The fallen trunks piled up in ever-thicker layers, buried beneath new sediments and new vegetation, slowly compressed and heated over millions of years until they became mineral coal. It is one of the most extraordinary ironies in the history of the earth. The energy that powered the factories of the British Industrial Revolution, that transformed the modern world, and that is now driving climate change, is solar energy captured by arborescent lycophytes that lived in the swamps of Pangaea 300 million years ago. There is a fascinating and widely debated hypothesis about why so much organic matter accumulated without decomposing during the Carboniferous. The hypothesis that fungi capable of breaking down, lignin had not yet evolved. Lignin, the polymer that hardens wood, is an extraordinarily difficult molecule to degrade. Today, white-wrought fungi, especially the basidiomycetes, are the main organisms capable of breaking down lignin. And they do so by means of specialized enzymes that took millions of years to evolve. Some researchers have proposed that during the Carboniferous, those enzymes did not yet exist or were very inefficient, which allowed wood to accumulate without decomposing even under conditions where it would rot quickly today. It is an elegant but controversial idea. Other scientists argue that the anoxic conditions of the swamps are enough by themselves to explain the accumulation of organic matter, with no need to invoke the absence of lignin-degrading fungi. The forests of the Carboniferous had a dramatic effect on the atmosphere. The enormous quantity of carbon that plants fixed through photosynthesis, and that was buried in the swamps without decomposing, drew carbon dioxide out of the atmosphere at an accelerated rate, while the oxygen produced by photosynthesis accumulated. The result was a rise in atmospheric oxygen levels to values between 30 and and 35%, far above today's 21%. That excess of oxygen had a spectacular consequence. It allowed the existence of giant insects. Meganura, a dragonfly with a wingspan of more than 70 centimeters, patrolled the skies of the Carboniferous like an aerial predator the size of an eagle. Arthropleura, a millipede more than 2 meters long, crawled across the floors of the swamp forests, feeding on decaying plant matter. Insects breathe through trachea, tubes that carry oxygen directly to the tissues, and the maximum size they can reach is limited by the concentration of oxygen in the air. With 35% oxygen, that limit shifted upward, allowing arthropods to grow to dimensions that would be impossible today. The end of the Carboniferous and the transition to the Permian brought dramatic changes for the forests. As Pangaea came together and the climate grew more continental and drier, the swamps that sustained the giant lycophytes began to retreat. Lepidodendron and Sigillaria, which depended on permanently soaked soils to reproduce by means of spores that needed water for fertilization, were the first victims of the drying climate. By the end of the Carboniferous, the lycophyte forests had disappeared from much of the equatorial zone they had dominated for millions of years, replaced by communities of primitive conifers and seed ferns that could tolerate drier conditions. It was the first great extinction of forests in history, an event that paleobotanists called the collapse of the Carboniferous rainforest, and it had direct consequences for the fauna. The giant amphibians that had thrived in the swamps lost their habitats, while the reptiles, which did not depend on water to reproduce thanks to their amniotic eggs, diversified rapidly to fill the vacant niches. While the giant lycophytes dominated the swamps of the Carboniferous, another group of plants was quietly developing an innovation that would end up being far more important than lignin, roots, and leaves combined. The seed. The first seed plants appeared as early as the end of the Devonian, about 360 million years ago, but during the Carboniferous they remained supporting players, relegated to the drier and higher ground where the swamp lycophytes could not grow. The seed solved a problem that spores could not. Spores, which are single cells released into the air to be dispersed by the wind, need to find a moist environment in order to germinate. If a spore lands on dry rock or arid soil, it dies. A seed, by contrast, is a capsule containing an already formed embryo, surrounded by a reserve of nutrients and protected by a hard coat that isolates it from the environment. A seed can remain dormant for months, years, or even decades, waiting for conditions to be right for germination. It is, in essence, a self-contained survival kit that allows a plant to reproduce in dry environments where spores would fail. Seeds also had another advantage that spores did not possess: internal fertilization. Spore-bearing plants, such as ferns and lycophytes, need liquid water so that the sperm can swim to the egg and fertilize it. It is the same system used by amphibians, and for the same reason it confines them to humid environments. Seed plants solved this problem by developing pollen, microscopic grains that carry the male genetic material through the air, with no need for water, to the female structure of the plant, where fertilization takes place in a protected setting. Pollen freed plants from their dependence on water for sexual reproduction in the same way that the amniotic egg freed reptiles from their dependence on water for animal reproduction. And that liberation had gigantic consequences. Seed plants could colonize the driest environments on the planet, from mountains to deserts, from steppes to summits, environments where a spore-bearing plant simply cannot complete its reproductive cycle. The seed and pollen, together, opened the door to the plant colonization of the entire land surface of the planet, including regions that had remained sterile for billions of years. When the first conifers began to grow on the dry slopes of the Permian Mountains, they were doing something no plant had been able to do before: living where there was no water available for reproduction. And that ability changed the distribution of life on land forever. The first seed plants, the so-called pteridisperms, or seed ferns, diversified during the late Carboniferous and the Permian. But it was after the great mass extinction at the end of the Permian, 252 million years ago, that seed plants took definitive control of terrestrial ecosystems. The arborescent lycophytes, which had depended on swamps to reproduce, went almost completely extinct when the climate of the late Permian grew drier and the swamps disappeared. Seed plants, which did not need swamps, survived and filled the voids. Conifers, ginkgos, and cycads became the dominant vegetation of the Mesozoic, the trees that the dinosaurs knew during the 160 million years of their reign. But perhaps the most profound consequence of the angiosperms for the history of the planet was their effect on the weathering of rocks and, through it, on the global climate. Angiosperms have been finer, denser, and more highly branched roots than conifers, which means they penetrate the soil far more effectively and break up rock at a significantly faster rate. Some geochemists have proposed that the expansion of the angiosperms during the Cretaceous accelerated the chemical weathering of silicates, drawing carbon dioxide out of the atmosphere and contributing to the long-term global cooling that would culminate in the glaciations of the Cenozoic. If this hypothesis is correct, flowering plants did not only change the appearance and composition of terrestrial ecosystems. They changed the temperature of the entire planet, gradually cooling it over tens of millions of years until it produced the ice ages that shaped the evolution of mammals and, eventually, of human beings, flowering plants may have created the climatic conditions that allowed our own evolution. And they did so without knowing it, simply by sinking their roots into the rock. But the true revolution, the one that transformed the planet more profoundly than any other plant innovation, took place during the Cretaceous between 130 and 66 million years ago. The explosion of the angiosperms, the flowering plants. Charles Darwin called the origin of the angiosperms an abominable mystery because he could not explain how they had appeared so suddenly in the fossil record and diversified so rapidly. Today we know a little more, although the mystery has not been completely solved. Angiosperms had several competitive advantages that conifers and cycads could not match. They could grow faster, going from seed to reproductive adult in months or years rather than the decades that conifers needed. They produced flowers that attracted pollinating insects with bright colors, scents and nectar, ensuring a targeted pollination far more efficient than the wind pollination on which conifers depended. And they produced fruits that protected the seeds and gave animals an incentive to eat them and disperse them over great distances, a free distribution system that no conifer could match. The co-evolution between angiosperms and pollinating insects was one of the most successful biological innovations in the history of life. Bees, which appeared during the Cretaceous, became the most efficient pollinators in the world, visiting flower after flower and carrying pollen with a precision that the wind could never achieve. Butterflies developed elongated proboscis to extract nectar from tubular flowers. Beetles, which had been opportunistic pollinators since the early Mesozoic, specialized in the flowers of particular plant families. And each new adaptation in the insect provoked an adaptive response in the plant, and vice versa, in a cycle of co-evolution that produced the astonishing diversity of flowers that exists today, more than 300,000 species of angiosperms, each with a flower designed to attract a specific pollinator. Angiosperms did not stop at flowers. Their last great invention, which would not arrive until the Cenozoic, was grass. The grasses, the family of plants that includes wheat, rice, corn, sugarcane, and the grasses of the prairies and savannas, appeared about 70 million years ago, but did not become dominant until the Miocene between 23 and 5 million years ago, when global cooling and reduced rainfall turned forests into open grasslands. Grasses invented a trick that no other plant had managed, growing from the base instead of from the tip. That meant a herbivore could eat the entire upper part of the plant, and the grass would immediately grow back from below, with no need to regenerate the growing tip that an animal had just devoured. Grass was, for the first time in the history of life, a plant that benefited from being eaten. From the cyanobacteria that invented photosynthesis more than 2.5 billion years ago, to the grasses that feed humanity today, the story of plants is the story of the planet. Every step of that story, the endosymbiosis that created chloroplasts, the colonization of land, the invention of vascular tissue, the appearance of wood, roots, leaves, seeds, and flowers, was an evolutionary leap that transformed the earth permanently and irreversibly. Without plants, the land surface would still be a desert of rock. Without plants, the atmosphere would not have enough oxygen to sustain a single animal. Without plants, there would be no soil, no forests, no food that we eat, and no air that we breathe. Everything that life has built on dry land rests on a green foundation that plants laid one by one over 3 billion years of silent evolution. If this story has made you look at plants in a different way, share it with someone who is also amazed by the history of life. And if you want to keep discovering how our planet has changed over millions of years, subscribe to the channel and join us for the upcoming episodes.