How did life originate on Earth?
Let’s define life first. Anything that has life has molecular movement within them. The only exception being virus. This is the most basic definition of a living thing. Obviously, they might do a host of other stuff too. But one thing remains certain, the building blocks of life on earth are Amino Acids. Amino acids are the smallest divisions of proteins, consisting of NH2 and COOH groups. Initially, earth was a very hostile place. Life as we know today would have no chance of existing in those conditions. So what paved way for life?
There are various theories regarding the origin of life. I’d like to discuss two of them here.
Charles Darwin’s theory of evolution:
Darwin’s theory was simple. Initially, life originated by spontaneous generation which means that Organic life was created out of inorganic substances. The development of life after this could be explained by evolution. Thus complex organic life began from the simple inorganic substances.
The initial inorganic to organic conversion has been proven to be true, up to a certain extent by the Miller-Urey experiment. What Miller and Urey did was that they simulated the early conditions of earth in a science laboratory. The early atmosphere largely consisted of Ammonia, methane and hydrogen. Miller sparked the mixture with electricity and supplied light. After a couple of weeks, he found organic substances i.e amino acids. Further experiments have confirmed that all the 20 amino acids found in organisms can be formed by replicating infant earth.
I had said that experiments proved Darwin’s words up to only a CERTAIN extent because these experiments have failed to show LIFE originating from inorganic substances( Spontaneous generation). They have merely shown that organic substances can emerge from inorganic substances, provided the conditions are right. The only argument we can give about this failure is that we do not have enough knowledge about Earth’s conditions after the formation of amino acids.
So, according tho this theory, life originated by accident. It would’ve taken millions of years for amino acids to assemble the exact way to support life. It all boils down to probability.
Another theory is that life did not originate in earth. Instead, it came from outer space via an asteroid. Simple life forms like bacteria might have been embedded within the asteroid surface , frozen and protected by the vacuum of pace. On collision with earth, the frozen bacteria would have touched land and replicated. After that, evolution followed.
If this is the case, then life must be all around space. The asteroid belt must be teeming with frozen bacteria. We can surely test this by sending a probe to an asteroid. Maybe asteroids are Adam and Eve.
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