A little over 4 and a half billion years ago, Earth was molten lava. You would have had no idea it was the same place. In its earliest stage of formation, it was clumped from a cloud of dust, totally uninhabitable. Around 1,000,000,000 years ago, though, Earth had its first signs of life. Single-celled organisms used the sun’s energy. And, as a waste product, these bacteria slowly filled the oceans and atmosphere with oxygen.
An oxygenated atmosphere made way for more complex life.
100,000,000 years ago, dinosaurs roamed the Earth.
10,000,000 years ago it was mammals.
100,000 years ago was when homo sapiens truly evolved.
In this timeline, Neolithic architecture lays out all the pieces on the floor. What sequence of events has unfolded for Earth to support life to our current times?
1) Beginning of Earth: 94.6-4.0 billion years ago
The Big Bang created all matter. It is believed to include the sun, planets, our solar system and beyond. At the center, the sun swept in lesser elements like hydrogen and helium. Farther away, heavier elements formed planets. Based on the core accretion model, gravity was a core driver coalescing Earth from a cloud of dust.
In this early stage of Earth’s creation, the heaviest material like iron sank. Lighter material remained on top to form a crust. Because a solid inner layer heats the outer liquid layer, it produces convection. This form of geodynamics created Earth’s magnetic field. Without it, Earth would have been totally baked by harmful rays from the sun. During this stage. Earth was also hit by many asteroids, comets, and foreign objects badly. We know because we can see these on other planets. Many scientists believe that from these collisions, water originated, and could have also sparked the chemical building blocks for life or DNA.
The moon impact was one of the most important events for Earth. The giant impact hypothesis describes an object the size of Mars that hit earth at tremendous speed. After impact, gravity pulled the object into orbit. Ever since this event, and the hadean eon, it has remained in orbit.
2) Primitive life earth temperature lowering 94.0-2.5 billion years ago
The collision of the moon into Earth impacted earths climate, oceans, and life. It slowed Earth’s rotation significantly, dragging us from 6-hour days to 24 hours. It also stabilized the Earth from wobbling. And, more importantly, it tilted Earth on its axis, and because of this, Earth now had seasons.
In the archean eon, the climate on Earth became more suited to different forms of life. Instead of a molten state, the Earth became cooler. Water vapors condensed to form oceans, and these conditions formed continents. Though scientists debate, “vaalbara” may have became Earth’s first super continent. During when oxygen was absent in the atmosphere, as new forms of life began, cyanobacteria was continuously converting sunlight into energy. They metabolized their own food as a waste product and released into the oceans.
In the oceans, where the oxygen mixed with iron, rust collected on the seafloor. This banded iron formation continued until there was no more iron in the oceans to rust. And, oxygen had nowhere to go but into the atmosphere. That’s why this event is known as the great oxygenation event.
3) The start of air 2.5 billion to 541 million years ago
Earths atmosphere was now oxygenated. New life begain to flourish on Earth. But cyanobacteria was not flourishing. Oxygen was toxic for themselves. It poisoned anaerobic life on Earth including there own. Imagine humans polluting the planet until extinction. The oxygen byproduct from cyanobacteria created an oxygen crisis on Earth. During this time, methane was more abundant in our atmosphere. One thing methane did was trap heat in the atmosphere. It’s one of the most efficient greenhouse gases, and when oxygen combined with methane, it produced carbon dioxide. All of a sudden, the greenhouse effect wasn’t doing its job. The side effect was the whole planet freezing. It was a giant igloo as we went into an ice age for the next 300,000,000 years.
Aerobic eukaryotes were another important consequence of an oxygen-filled atmosphere. Before the oxygenation, life was anaerobic. Aerobic respiration organisms emerged because of the enriched atmosphere and availability of oxygen. This increased the complexity of organisms and life. For example, multi-cellular organisms became appearing. But the abundance of CO 2 held many eukaryotes from diversifying.
Over the thousands of years, as oxygen eventually filled the atmosphere, Earth’s ozone layer thickened. Because water shielded harmful solar radiation, before the ozone layer, life was restricted to shallow water. Finally, the thicker ozone enabled life to diversify on land in what was known as our proterozoic eon.
4) The Cambrian Explosion Paleozoic Area: 541- 245 million years ago
The cambrian explosion diversified everything and included the largest amount of life in history. This is when hard-shelled invertebrates, similar to what is found in diatomaceous earth, and larger begain originating in our oceans. The age of invertebrates originated after the precambian explosion. Diversity increased from there. There was a age of fish when thousands of fish species arose. And, the first vertebrate land animal made its leap ashore. Amphibians even rose to colonized the empty continent of Gondwana.
In the paleozoic era, rich vegetation’s flourished the land. Then, due to a giant change in climate, a major marine and terrestrial extinction event began. It was known as the carboniferous rainforest collapse. Lush plants and oceanic organisms were buried, compacted, and baked into coal deposits below the earth. It left behind large wastelands for reptiles to dominate the mainland.
The paleozoic era ended with the largest extinction in Earth’s history. The permian-triassic extinction vanquished 96% of all marine species. About 90% of terrestrial vertebrate species were wiped out. Opinions differ about the permian-triassic extinction. However most believe it was a major collision with earth and number of other factors and occurrences.
5) The Age of Reptiles and Dinosaurs: 245 to 66 million years ago
Rainforests collapsing triggering the age of reptiles When earth’s climate became hotter and drier. Reptiles do not lay eggs in water and are different from amphibians because they lay their hard-shelled eggs on land. Essentially they adapted to the land. Because of it, they gained a unique ecological advantage.
Due to the changing conditions, dinosaurs began to evolve. These reptile-like animals had scaly skin and hatched eggs like reptiles. Some dinosaurs adapted as plant eaters and some as meat. For the next 160 million years, dinosaurs were the dominant land vertebrates.
A sub age, the age of conifers in the mesozoic era provided the spread of seeded plants. Conifers store vast amounts of carbon. As a result, oxygen content jumped to 35% compared to 21% oxygen in the atmosphere today. In addition, they provided habitat, shelter, and a source of food for specific animals and species to survive.
Also notable is that, in this stage of earth, pangea existed as one super continent. It is believed dinosaurs lived on the one super continent but plate tectonics eventually mechanism that tore continents apart. 160 million years was a long time for dinosaurs to exist. Continental drift gradually drifted dinosaurs apart. We know this because there isn’t the same fossils on separate continents.
6) The Age of Mammals and Homo Sapiens: 66 million years ago – now
Ultimately, something big happened again, and started the cenozoic era. It was the end of dinosaurs. Scientists believe a 6 or 7 mile wide asteroid hit Earth. There were a number of other factors (typhoons, axis shift), and a dust cloud blocked the sun. This caused temperatures to plummet and was believed to be the core damage from the cretaceous–paleogene extinction event. Because of the global climate disruption, it was responsible for the extinction of dinosaurs. Though, mammals did exist before the cenozoic era. They just kept a lower profile because dinosaurs were so giant. So, the extinction of the dinosaurs setup the age of mammals. When dinosaurs roamed the Earth, mammals remained small and furry. And because dinosaurs were gone, mammals emerged as the largest land animals at this time. Apes and monkeys remained in trees for their primary food source. Eventually, grass began to spread in places like the African savannah and there were fewer trees. This forced apes to walk to new food sources. Having to see predators, they evolved to walking with there heads above the grass to see predators. It also helped to have their hands available when they were traveling.
As the timeline to modern human evolution began, it was believed hominids were the early proto-humans. They were known for there adaptability, and sharpening objects with rocks for survival and protection. They began to master the use of their bodyparts, hands, and fingers. In the early stone age, humans had fire under control. It enabled them to cook food better, giving more nutrition and calories. It allowed them to make more complex sounds, share information and learning in groups.
According to all this information, humans have only existed for about 0.004% of the age of the Earth.
Geologic time is so vast and unimaginable yet it provides a basis for understanding neolithic architecture. Its hard to imagine planet earth spans over 4.5 billion years. One thing is for sure. Since its creation, oceans, continents, and life as we know it has incredibly changed. And, as necessary, we have evolved and adapted.
Kasting, James F.; Catling, David (2003). “Evolution of a habitable planet”. Annual Review of Astronomy and Astrophysics. 41 (1): 429–463. Bibcode:2003ARA&A..41..429K. doi:10.1146/annurev.astro.41.071601.170049.E. (2022, May 13).
Earth Timeline: A Guide to Earth’s Geological History and Events [Infographic]. Earth How. https://earthhow.com/earth-timeline-geological-history-events/
Fortey, Richard (September 1999) . “Landwards, Humanity”. Life: A Natural History of the First Four Billion Years of Life on Earth. New York: Vintage Books. pp. 138–140, 300. ISBN978-0-375-70261-7.
The Editors of Encyclopaedia Britannica. (1998, July 20). Geologic time | Periods, Time Scale, & Facts. Encyclopedia Britannica. https://www.britannica.com/science/geologic-time