Have you ever imagined, the food we eat, the water we drink, the land we live on, animals and plants we see, from where all these things come from? How and when our earth was formed? How human life came on earth?
It has been known that there are a total of 87 lakh species on earth and we have discovered only about 15% of all species.
Before going to the formation of the earth and human life on earth, we have to understand how our solar system gets formed. We all know that Sun was the first planet to form and because of the sun, all others come to existence.
How our sun was formed?
Almost 5 billion years ago
Before our earth and other planet were formed, There were only gravity and some clouds of dust freely roaming here and there in space known as the solar nebula. As the nebula collapsed because of its gravity, it spun faster and flattened into a disk. Most of the material was pulled toward the center to form the sun because of the conservation of angular momentum.
Lighter particles like hydrogen and helium in sun began to go outside from the sun, while heavy particles like dust and rock began to concentrate at the center of the sun. There was still so many dust left in the solar system which gives rise to other planets including our earth.
How and when our earth was formed?
4.5 billion years before.
As like our sun was created, our earth was created in the same way. The core part of the earth was made up of iron and nickel(Heavier particles) while the crust part was made up of lighter materials. In the initial years, there is no possibility of life on earth.
The temperature of the earth at that time was about 2000 Degree Fahrenheit and the earth was covered with molten lava. Continuously large number of stone was falling on earth from space. Slowly, molten lava began to convert into hard land but the temperature was still high.
Formation of moon
After 1 billion years, mars sized protoplanet named THEIA roaming freely in space suddenly began to come closer to earth. Eventually, he collapses with earth and thus a large number of debris began to circulate the earth. Thus from leftover debris of earth, the moon was formed just like all other planets.
The gravity of the moon is the main reason our earth does not move from our axis, making life possible to grow.
3.9 billion years before
At this stage earth has become a hardball with no molten lava over the surface and temperature was also decreased. Suddenly fireballs and large meteorites began to collide with the earth which is known as the late heavy bombardment.
This time, there was something special in a meteorite which is essential for life and it was ice crystals and nitrogen. Due to the melting of ice crystals from meteorites, our earth was covered with water. but still, there was no trace of oxygen, and the environment was full of toxic gases.
Again, there was a rain of meteorites on earth. This time along with meteorites there was minerals, carbon dioxide, protein, and amino acids. As the earth was covered with water, there was a certain amount of chimneys which was keeping water warmer. In no sunlight, the first unicellular bacteria develops underwater. Exactly, we don't know how these bacteria come into existence but it has been understood that there might be some chemical reaction involved in the process.
3.5 billion years before
The number of unicellular bacteria goes on increasing and these bacterias converted into a large number of stones called STROMATOLITES. Due to these stones, it began to perform the photosynthesis process and started to release oxygen as a byproduct. Till 2 billion years this process continues to happen and oxygen level on earth began to rise.
1.5 billion years before
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| Image source:- Carnegie Science |
Still, there was no complex cellular life developed. There were many small islands covered with water but due to vibrations in the crust, the surface was divided into tectonic plates. Movement in these plates gave rise to a supercontinent called RODINIA. At this time, the temperature was about 30 Degree Celcius and 1 day was 18 hr long.
75 Crore years before
Again due to vibrations, the supercontinent was divided into two parts and molten lava began to come outside, and once again environment was full of methane and hydrogen. Due to the chemical reaction in methane and hydrogen, carbon dioxide levels began to increase and it led to acid rain. This acid rain begins to settle in the form of carbon dioxide on the rocks.
Suddenly CO2 level begins to drops and temperature was also drastically decreased, this incident led to our first ice age. This ice age was the longest ice age of now.
Again due to uncertain conditions, ice began to melts and CO2 level start rising with the temperature.
54 crore years before
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| Anomalocaris |
Earth comes to its normal condition, as it was before the ice age. unicellular bacteria in the water get converted into a multicellular organism like ANOMALOCARIS which was the largest creature at that time. All these complex lives evolved using unicellular bacteria.
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| Pikaia |
PIKAIA was the first creature with vertebrates, we humans will going to evolve through pikaia. Pikia was just 5cm long.
46 crore years before
Now, the formed earth was almost identical to look as compared to today. Super continents were also divided into many parts. There was still no life on land, this was due to UV rays coming from the sun. To stop these UV rays, ozone layer began to develop. Oxygen present in the environment began to consume ozone light from the sun and emits ozone gas, this gas will become the ozone layer in the future days.
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| TIKTAALIK |
Due to the ozone layer, life on land becomes possible. A fish named TIKTAALIK was the first fish who decided to come to land. He uses his fins as legs to walk on land.
It takes approximately 1.5 crore years to be able to walk on land as well as in water for this fish. We gave name to this species as TETRAPODS.
36 crore years before
Later, many species will get evolved form tetrapods included Mammals, birds, dinosaur, etc.
overtime, many volcanic eruptions happen due to which temperature began to rise again. This famine destroyed almost 95% of species. Only those creatures were able to survive, who was started living inside the ground and started to eat anything.
20 crore years before
overtime, the temperature began to normalize and the earth was again identical to look as compared to today. PANGEA, a supercontinent was formed due to volcanic eruption.
5% species which was left during a volcanic eruption, they started living inside the ground and will further evolve to dinosaurs. The dinosaur lived almost 14 crore years.
14 crore years before
Along with dinosaurs, there was another species known as mammals(Don't lay eggs, directly give birth to young ones). In the real sense, humans have evolved from these mammals. Mammals used to live underground and he looks like a mouse.
Extinction of dinosaurs
When everything was perfect, suddenly an asteroid of 10km diameter starts coming closer to earth. Due to friction while entering in a gravitational field with a speed of 70000 km/hr, a black asteroid was converted into a large fireball.
Those animals who were in the range of 800km w.r.t asteroid became blind due to very high intensity of light. Right in front of eyes asteroids collide with the earth and a large amount of element flew into space. At the place where asteroid collided, 20 km deep and 1180 km wide hole got created.
Due to this collision, an earthquake reaches the core of the earth, and tsunami begins to occur in sea. Radiation was more enough to burn all the animals within 800 km of an asteroid. Water vapor from the cloud began to evaporate due to the amount of heat.
Along with this, the dust storm was also approaching with a speed of 2000 km/hr. Earth was fully covered by dust and hence no sunlight can able reach the surface. Resulting, the temperature was increased up to 150 degrees C. 75% of species vanished due to this great holocaust.
All dinosaurs vanished, but mammals who were living inside the ground somehow able to survive. To survive, mammals began to eat anything and overtime he will evolve further in many species.
4.7 crore years before
At this point, almost every continent was formed and the temperature was about 24 degrees C and one day was long as 24hr. Again, due to vibration in tectonic plates, India began to move towards the Asia continent.
India and Asia's continent collided with each other and a new Himalaya formed named Mount Everest. Due to this Himalaya, many rivers got created and in the future, it will provide drinking water to the majority of the population.
Up to this, we have understood how and when our earth was formed, and further, we will see how humans came into existence.
40 lakh years before
A new Himalayan was formed in the eastern region in Africa named East African Rift Valley. This Himalayan become an obstacle to the monsoon winds due to which rain completely stopped falling in the forest.
Apes lived in this forest on trees, which become drought land to live due to a shortage of rain. As a result, there was a shortage of food in the trees and apes decided to come to the ground for eating purposes.
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| ARDIPITHECUS RAMIDUS |
ARDIPITHECUS RAMIDUS was the first species to come to land. Their brain was the same as the size of an orange and as tall as 4 feet. After years, they began to walk on two legs and can eat at the same time.
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| Homo erectus |
They invented fire to protect from cold and animals, tools to hunt their food and they learn to live as a group. Homo erectus was the first species to live as socially. Later on, they invented languages that became the largest invention of all time.
2 Lakh years before
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| Image source:- Britannica |
Homo sapiens(we) become the most intelligent species of all time and had invented language, tools, and fire to communicate, hunt, and protect respectively.
Feel Free to ask any questions.
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