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Origin of Life on Earth

Updated on 07 January 2021
6 min read 4 views
Updated on 07 January 2021

Life on Earth began around 3.5 billion years ago. It was said that dinosaurs were the oldest creature on Earth as they have their beginnings 200 million years ago. However, the Oldest known fossils are around 3.5 billion years ago. Till then many theories have come into existence but none of them got approved hence there is no fully accepted theory till now. In this article, we will see the origin of life on earth and its related information briefly to understand this concept better.

First Life on Earth

The earliest life we know is the microscopic organisms, microbes that left signals of their presence in rocks around 3.7 billion years ago. These signals contain a type of carbon molecule which is produced by living beings. After that, the first animal on earth was a comb jelly.

Why Life is Possible on Earth?

Why is life Life found only on the earth? Well, this question must be in everyone's mind. Below we will see why life has only been found on Earth. However, it is important to know that there are a couple of reasons needed for human survival and the earth possesses all of them. These are-


Oxygen is the most needed gas not just for humans but for many other creatures too. Earth has 21% gas in its atmosphere which makes it the most breathable planet. Oxygen is constantly generated by the plants and trees. However, other planets like Venus and Mars have most of the carbon dioxide gas in their atmosphere which is not suitable for humans because they are the most poisonous gas. 

On the other hand, Mercury is too small to keep the atmosphere. Other than this the Earth's atmosphere is thick i.e. 3 layers that are enough to prevent poisonous radiation from entering the atmosphere. 


Earth is situated in the right direction from the Sun thus it doesn't have extreme weather. However other planets like Mars can reach a temperature as low as -150°c, a temperature which is too cold to survive. It can also freeze human blood. 

Venus has a temperature of around 480°c which is too hot for anyone to live. Hence Earth has the perfect moderate temperature which is neither too hot nor too cold. 


Life cannot sustain without water. Water is the most essential requirement of any creature be it humans or animals. Only Earth has an abundance of water throughout the world available in oceans, lakes, streams, rivers, etc. Also, the earth has water in all three states- solid, liquid, and gas.  This one of the most important reasons why life is found only on the earth and not anywhere else.


Light is essential for human survival. And not just humans they are required by plants also to carry on their process of photosynthesis. Earth is the only planet that gives light to each side of the planet regularly by spinning on its axis just under 24 hours means each side of the planet receives regular light. While the other planet like Venus takes 243 days to spin on its axis, which means that for a longer period of time certain parts of Venus don't enjoy the light.

Right Moon

Our large moon ensures climate stability and minimizes the change in planetary tilt which avoids extremes temperatures.

Earth’s Structure

Earth is made up of 3 different layers- the crust, the mantle, and the core. Earth's core helps in protecting from harmful sun radiations which are not available on any other planet.

Why Life is found Only on the Earth?

Now we are aware that life requires Sun, water, moderate temperature, and certain chemicals like oxygen, carbon dioxide, and nitrogen. No other planet has a moderate temperature which is not too hot or not too cold. Although there is ice on other planets where there is no trace of liquid water on any other planet than Earth.


From NASA probe Mariner 4 first attempt to find first life on Earth to phoenix lander all have failed to prove that life exists on Earth. Because water is only present in the form of ice i.e. solid state and not in a liquid state and also because of the extreme weather conditions thus life cannot sustain there.

As of now, Life can only exist on Earth due to its perfect balance of oxygen, poisonous gases, water, sunlight, etc. which can sustain life in the best possible way.


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