Earth - the planet we inhabit, whose predecessor was completely different from the forms existing today. It began its existence from a chaotic, highly molten state that even the most extreme scenarios in cinema could not adequately simulate. So what core factors created life and human civilization?

Earth - the planet we inhabit, whose predecessor was completely different from the forms existing today. It began its existence from a chaotic, highly molten state that even the most extreme scenarios in cinema could not adequately simulate. So what core factors created life and human civilization?

Based on modern computational models of the Solar System and the analysis results of the oldest rock samples discovered on Earth's surface dating back over 4 billion years (specifically 4.03 billion years in Canada and 4.4 billion years in West-Central Australia), contemporary scientists have concluded that Earth was formed about 4.7 billion years ago. This is the result of the gravitational accretion of millions of asteroids, dust, and gas on a disk of material orbiting the early Sun.

In its primordial era, Earth existed solely as a dead planet with extremely high thermal levels. Heavy metals gradually sank deep into the center and melted, while pushing lighter materials to the surface to gradually cool down. Earth at this time had the shape of a giant black sphere with glowing cracks due to the molten material escaping from inside. This system of cracks would continue to exist for billions of years to come, frequently acting as the key factor determining the survival or extinction of life forms on the planet.

Initially, Earth was just a scorching dead planet.

About 4.3 billion years ago, a hypothetical planet roughly the size of Mars called Theia (formed during the early construction phase of the Solar System) moved and collided with Earth. This collision represented a true catastrophe, but simultaneously was a decisive prerequisite for human life later on. First of all, it made the distribution of matter on Earth more uniform, similar to the reaction when you vigorously shake a container with many types of particles at once. Next... this event led to the formation of the Moon. Material from the surfaces of both planets was blasted into space, forming an active ring of material moving in orbit around Earth, similar to the rings of Saturn and today's giant gas planets. Gravity once again played the role of a creator factor, gathering the debris to form the lunar satellite.

At that time, the Moon was located very close to Earth and Earth rotated at a very fast speed. If this situation had persisted continuously, life would have been extremely difficult to form. However, thanks to the presence of the Moon, Earth's rotation speed gradually slowed down due to the influence of gravitational tidal forces, while centrifugal force pushed the Moon further away. This phenomenon helped the planet avoid tides dozens of times stronger than the most terrible tsunamis of the modern era. That was the period about 4.1 billion years ago when the primordial oceans and the atmosphere (completely devoid of oxygen) were in the process of forming.

A planet the size of Mars named Theia (formed in the early stages of the Solar System) collided with Earth.

During the era from 4.1 to 3.8 billion years ago, Earth's surface was gradually filled with oceans because the cooling process of the planet allowed the persistent existence of liquid water. Small asteroids and meteorites continuously bombarded Earth; they were the remnants of material from the early construction period of the Solar System. It was these meteorites that transported hydrated crystals and the simplest organic compounds into the primordial oceans, where life would emerge in the later stages.

3.8 billion years ago, Earth entered the Archaean Eon. This is the middle stage of the Precambrian period. From the foundational organic compounds brought by meteorites attacking Earth, amino acids formed in the marine environment, and the first simplest cells began to take shape. Unlike us today, they were structured based on RNA molecules (Ribonucleic acid, distinct from DNA, Deoxyribonucleic acid, which makes up modern plants and animals). Today we have found fossils of the first life forms with the oldest age being 3.5 billion years. The first cells were essentially unicellular life forms, gradually combining into thicker layers called stromatolites. They were the first life forms to perform early photosynthesis to provide oxygen for our planet. The first simple glucose compound (sugar) was also formed.

3 billion years ago, the oceans were pumped full of oxygen; iron dissolved in the oceans was heavily oxidized and sank deep down to form iron ore deposits. The massive architectural structures we have today were built from this 3-billion-year-old ore.

2.5 billion years ago, the Proterozoic Eon officially began. This was the initial development period of primitive organisms on Earth, the final stage of the Precambrian. The first multicellular plants appeared around 1.2 billion years ago with a more complex genetic structure based on DNA instead of RNA as before.

However, the development of life did not last long before it was forced to a halt. The progression of time almost stopped when Earth entered the longest and most intense global glaciation phase in its geological history. About 850 million years ago, the excessively high oxygen density in the atmosphere prevented the absorption of solar radiation; Earth did not receive thermal energy, so it cooled and gradually froze. The more ice that formed, the more sunlight was reflected back into space because the entire planet at this time acted as a giant mirror absorbing absolutely no light.

The entire Earth at that time was a giant ice sphere, without a trace of life.

This period lasted continuously for over 200 million years. We know that modern humanity, with a history that seems very long, actually only truly developed civilization and intelligence in the late stage of the most recent ice age, about 15,000-20,000 years ago. Meanwhile, just this period of freezing the entire planet lasted for over 200 million years. The entire Earth at that time was a giant ice sphere, showing no trace of life or the warmth of the Sun; any light rays from the Sun reaching it were bounced back into vast space.

630 million years ago, the molten lava source within Earth's core was awakened, becoming the savior for life on the planet. Volcanoes, after hundreds of millions of years of dormancy, awoke and erupted violently; they broke through key freezing points on Earth's surface, spewing lava onto the surface, and most importantly, releasing carbon dioxide. As we know, carbon dioxide is the main agent causing the greenhouse effect, and at this time, it was the exact savior for life on Earth. The atmosphere absorbed the Sun's temperature, along with volcanic eruptions melting the ice, creating conditions for the simplest life forms still existing deep at the ocean floor to have the opportunity to continue evolving. This ice-melting process lasted for several million years.

580 million years ago, multicellular plants had become quite common, and this was also the first period to see the appearance of primitive mollusks. Today we have found fossils of mollusks dating back to this era.

540 million years ago, oxygen continued to be pumped into the atmosphere, and in the upper layers of the atmosphere, which directly received sunlight, a new gas layer was formed from oxygen: ozone. This layer blocked harmful ultraviolet radiation from penetrating the atmosphere, and this was the core condition for life to begin invading the land (by this time the first continental plates had appeared).

About 530 million years ago, Earth entered the Paleozoic Era, starting with the first period, the Cambrian. This was a time of explosive biological development, lasting about 30 million years, often called the Cambrian Explosion. In the marine environment, more complex animals appeared, most typically trilobites and their relatives. Furthermore, this was the first recorded appearance of specialized predators, species that directly attacked other species for food instead of eating small plants or floating carcasses. For example, in the image below is an Anomalocaris preparing to kill its prey, a trilobite.

An Anomalocaris.

505 million years ago, the next stage of plant and animal development began; this was the second period of the Paleozoic, the Ordovician. The oceans invaded the entire Northern part of Earth, and biological development concentrated mainly on the Southern supercontinent, Gondwana. This was a period of strong development for mollusks and especially an explosion in the diversity of fish. The first fish species appeared and dominated the oceans from this period through the Silurian (440-410 million years ago) and the Devonian (410-360 million years ago).

In the Devonian period, 410 million years ago, a type of fish called Tetrapods made contact with land and used its fins to crawl up gradually. After millions of years of persistent evolution, they fully moved onto land, evolving into the first terrestrial animals; following them were the Ichthyostega. In addition, this was also a period of strong development for insects with morphologies quite similar to today, such as dragonflies or arthropods, but with much larger sizes. Not only that, plant species also grew to gigantic sizes, reaching tens of meters high due to the high oxygen concentration in the air.

A fish species named Tetrapods.

The period from 360 million to 286 million years ago was the Carboniferous period (also known as the Coal Age). This was a time when a vast array of plant vegetation died and settled into the earth, crystallizing into the coal deposits we mine today. Most importantly to mention, this was the period when animals began forming the habit of laying eggs on dry land. It should be noted that before this Carboniferous stage, animals, even when they had begun to invade the terrestrial world like some primitive reptiles and amphibians, still kept the habit of laying eggs in water because the young inside the eggs needed enough moisture to survive until birth. But by this period, reptiles had successfully evolved to lay eggs with fluid-filled membranes providing direct water to the embryo. The first two species considered the ancestors of later reptiles were Hylonomus and Paleothyris.

A Hylonomus.

Large trees died to form coal, while an equally massive generation of organisms appeared to replace them: moss clusters up to 30 meters tall, horsetails, and ferns over 15 meters tall, spreading across the Gondwana continent.

From 286 to 248 million years ago, Earth entered the final period of the Paleozoic Era, the Permian. This was a crucial period in the development of animals. Some reptiles evolved into the early stages of mammals, such as the therapsids in the image below, which evolved from Dimetrodon; it had a facial structure and teeth very similar to modern mammals, and it was also one of the terrifying predators of the Permian. However, unfortunately, mammals did not develop so easily; therapsids and many other animal species (mostly reptiles) of that time became victims of the most terrible extinction event in Earth's history: the Permian-Triassic extinction event (the Great Dying).

Therapsids.

To date, there are still many unsettled views on the specific cause of this disaster, but the majority of opinions suggest the cause of the great extinction was the merging of two supercontinents, Laurasia and Gondwana, into the supercontinent Pangaea. The collision disrupted the topography of both large continents, leading to earthquakes and volcanic activity on a continental scale that destroyed organisms. But the place most terribly devastated this time was the marine life; up to 95% of species permanently disappeared after this great extinction.

This great extinction marked the end of the Permian, transitioning to the next era called the Mesozoic.

248 million years ago marked the beginning of the Mesozoic Era, once the great extinction had ended. In the oceans as well as on land, geological transformations had paused, but natural conditions were no longer the same, and some species proved better adapted than others; they developed to become the rulers of the planet. The first period of the Mesozoic was the Triassic, marking the beginning of what is called the age of dinosaurs. This was the most prosperous period of development in the history of reptiles. Mammalian ancestors like Cynodonts continued to exist and persist, leading to the eventual explosion of mammals and ultimately the emergence of our species later on.

Cynodonts.

However, during this Triassic period, early mammals and even fish were vastly outmatched by the absolute dominance of dinosaurs. They were present everywhere, in sizes from small to large, and in various life forms. While at the bottom of the ocean, the rulers were Ichthyosaurus or Nothosaurus for a long time, on land, dinosaurs were even more prosperous. They were divided into 3 main groups: theropods (predators like T-rex, Coelophysis, or Allosaurus), sauropods including long-necked lizards like Apatosaurus, Mamenchisaurus, and finally the ornithischians including species like Triceratops (three-horned dinosaur), Stegosaurus (armored dinosaur), or even Iguanodon, as you have seen in the famous Walt Disney movie Dinosaur. The image below is a T-rex (Tyrannosaurus Rex), the most famous predatory dinosaur of the Triassic.

The tyrant dinosaur T-Rex.

213 million years ago, the Jurassic period officially began. This is the middle stage of the Mesozoic. The supercontinent Pangaea once again fractured into Laurasia and Gondwana. At these geological fracture zones, a massive destruction of organisms occurred, including plants, fish, and marine animals.

Consequently, they settled down and formed today's petroleum deposits; this is a very important point in Earth's geological history and contributes significantly to our modern world today.

Meanwhile, on land, reptiles continued to develop strongly. By the middle of the Jurassic, they completely dominated the air, land, and oceans, with the number of species increasing vastly compared to the Triassic period. Under the ocean, plesiosaurs appeared and ruled the deep seabed.

A Plesiosaur.

Meanwhile, dominating the sky were pterosaurs, winged lizards. However, they were not the direct ancestors of modern birds. Modern birds began to diverge during the Jurassic; a terrestrial carnivorous dinosaur evolved, growing feathers to become a transitional species between reptiles and birds. Archaeopteryx is precisely the ancestor of modern birds.

Archaeopteryx - the ancestor of modern birds.

Mammals during this period were merely small animals like modern mice; they were forced to live in persistent hiding to escape the hunting of dinosaurs.

145 million years ago, Earth entered the Cretaceous period, which was the final stage in the reign of dinosaurs, and also the final period of the Mesozoic Era.

The most notable point of this era was the appearance and proliferation of flowering plants, pollinated by insects, gradually replacing the older generation of plants consisting mainly of ferns and conifers. Dinosaur species no longer thrived as before due to such foundational changes in vegetation. However, they remained the undefeated rulers until 65 million years ago.

The vast majority of current scientific opinions lean towards the hypothesis of a destructive asteroid, backed by evidence of Iridium (an element that can only come from outer space) dating back about 65 million years found in Central America, in the present-day Gulf of Mexico region. This hypothesis suggests that an asteroid with a diameter of over 10km in the Solar System crashed into Earth. The horrific impact created the modern Gulf of Mexico and the largest tsunami and earthquake in the entire Mesozoic Era.

An asteroid with a diameter of over 10km in the Solar System crashed into Earth.

More importantly, this event caused massive qualitative shifts in the global climate. Terrifying volcanic eruptions along with meteorite attacks killed off massive numbers of large animals. Dust and soot from volcanoes as well as the impact blanketed the sky, preventing sunlight from reaching the ground, causing the mass death of crops and plants. The depletion of all food supplies coupled with sudden temperature changes was the most important factor leading to the mass extinction of dinosaurs.

However, in terms of devastation, this collision could not compare to the Permian extinction. Therefore, small reptiles and birds survived due to lower food requirements, as well as the ability to easily hide from the negative impacts of the disaster. And most importantly, our mammalian ancestors survived the catastrophe to enter the next era of Earth's history.

The Cenozoic Era

A world completely devoid of dinosaurs became empty for a long time when birds had not yet developed strongly and mammals were accustomed to hiding in deep burrows to avoid dinosaurs. It was not until nearly 60 million years ago that mammals emerged above ground and diversified into many forms, from predators to prey, and their significant enemies at that time were giant carnivorous birds.

About 55 million years ago at the end of the Paleocene epoch (a constituent part of the Cenozoic), primates began to appear in tropical and subtropical regions with biological traits far more flexible than other species, allowing them to adapt to their environment: forelimbs (later hands) with 5 digits, where the opposable thumb allowed for grasping and swinging from branches; a flexible neck structure allowing for observation from multiple directions... These were the very first ancestors of us today.

During the Eocene right after the Paleocene, from 55 to 33.7 million years ago, the global climate warmed, tropical forests expanded from the equator while ice concentrated at the two poles, especially Antarctica, seeing the appearance of many plant and animal species similar to today, most notably ungulates (hoofed animals) and some primate species closer to us.

Notable in this period were two typical groups of ungulates: Artiodactyla (ancestors of modern deer) and Perissodactyla (ancestors of modern horses and rhinoceroses); they were the common animals of this era. Horses at that time were quite small, only the size of small dogs today. Later they gradually went extinct, with only a few surviving to evolve into modern horses, zebras, and rhinoceroses.

A Mesonychid.

A very notable and important animal branch in the evolutionary history of life was the Mesonychids, which had a shape somewhat resembling wolves and hyenas; they were the predators of the era over 30 million years ago. By favorably adapting to the aquatic environment, they left the land, gradually adapting to their new habitat and later evolving into modern whales.

The truly close ancestors of humans only appeared about 3.7 million years ago; that is the furthest point in time to date where we can record the footprints of hominids capable of walking on two legs. This species is scientifically named Australopithecus, developing in the forested regions of Africa. The desertification of this continent turned forests into deserts or savannas, leaving no trees to climb; the Australopithecus species gradually evolved to adapt to living without treetops.

Australopithecus - a close ancestor of humans.

Australopithecus later evolved into Homo habilis with a much higher degree of similarity to modern humans, and further along was Homo ergaster, then Homo erectus with less body hair, primarily concentrated on the head, and body functions quite similar to modern humans.

Homo erectus is considered the first human-like ancestor of our human species today, with a brain size taking up about 74% of the modern human brain. That was about the era of 1.8 million years ago.

It wasn't until 100,000 years ago that the first intelligent humans truly appeared: Homo sapiens. They were the most intellectually developed branch among the developmental branches of the Homo hominid generation. With the desertification of Africa, they crossed the border between Africa and Europe, dispersing across both Europe and Asia (initially the Middle East region) today, living alongside bizarre animals during the ice age such as Mammoths or mammals with morphologies somewhat different from today's animals.

A Mammoth.

When the ice age entered its final stage about 12,000 years ago, humans truly entered their own era with social organizations ranging from small to large, from simple to complex. If dinosaurs were once the longest-ruling species on Earth in the history of this planet, conversely, we humans have occupied it for an incredibly short period but are the species with the most terrifyingly rapid rate of development in terms of population, social development, and science and technology. And what we have today, including the very lines you have just read, is the result of this entire process!