The True Origin Of Life; Abiogenesis [Survey of the evolution of life]

As a way of introduction, I would like to remind us that the origin of life is in diverse ways a “blank spot” in the chronicles and pages of history. And most of these have been left as mysteries. Like the mystery surrounding the big bang, and the dark matter. But we would not be looking at all these. We would be focusing on the puzzling origin of life form.

Note: No one lived through history to ascertain the accurate origin of life, but thanks to scientific research. We now have a holistic idea of what needed to happen for life to be triggered.

[Image Source]

Even though there are blank spots in the chronicles of history, there are some facts that could point us to the true origin of life. That is why we have to know about the current evidences and theories we have at hand (that is what history is all about).

Dawn of life

Scientists have postulated that the first life form began at the bottom of the ocean between 3.5-4billion years ago. There are also evidences to this.

In 1822, a German Chemist; Friedrick Wohler made his own exposition on this:

“Life” and “non-life” follow some chemical laws. And life may possibly emerge from non-life. – Friedrick Wohler

This exposition goes to buttress the theory of spontaneity. That life spontaneously emerged from non-life

[Image Source]

In the mid 19th century, another scientist rose; Louis Pateur. And he stated this:

Life must emerge from the inanimate world by chemical processes that are discoverable by science.

What did the early life look like?

Well, a whooping 2.1billion years out of the 3.5-4billion years of the evolutionary history of life was preoccupied by tiny single-celled organisms known as “prokaryotes”. Some of these prokaryotes evolved about 1.8 billion years ago into slightly bigger single-celled organism known as “Eukaryotes” (the trend kept repeating until humans finally emerged). 

[Image Source]

Believe me, the prokaryotes make up the vast majority of the family tree of humans (humorously, the same prokaryotes that ultimately evolved into humans also evolved into the microorganisms that cause diseases. That means, the virus that causes you flu is technically your cousin. Lol)

But even in its earliest form, single-celled organisms were greatly complex as compared to the inanimate universe.

Then the question is this:

How did the prokaryotes first emerge?

Firstly, it is very insane to think on how life would form on an oxygen rich atmosphere (like the present day earth). We know that oxygen is way too reactive to support the initiation of first life form.

But 3.8billion years ago, the free oxygen content of the earth was negligibly low. That was why life could thrive at its earliest form (the life forms were aquatic). And as life thrived deeply in the belly of the ocean, eventually some prokaryotes floated to the top of the ocean, and started making use of sunlight (in the first ever photosynthetic process). And as a byproduct, they pumped huge amount of oxygen into the atmosphere.

Around 2.6billion years ago, the oxygen level grew to 3% and couldn’t support majority of single-celled organisms, and they died massively (this was called “oxygen holocaust”). And some of the surviving prokaryotes quickly evolved into Eukaryotes. 

Before Eukaryotes, single-celled organisms did split to reproduce. But permit me to say that Eukaryotes invented “sex” (sexual reproduction).

Believe me, sex is classified as the major revolutionary advances in the history of life; and a huge boost to the rise of complexity on earth. All thanks to Eukaryotes.

Note: This trend of evolution does not take into consideration the possibility of “panspermia” (which postulates that life may have begun in another place in the solar system and transported into the earth by an asteroid)

[Image Source]

In the 1950s, it was discovered how living cells replicate using DNA. This was also a major booster to the common ancestry of all living things. Every living thing has DNA, and that is a reason we believe that all living thing sprang out of a common ancestor.

That is why humans share about 50% of their DNA with banana, and about 98% with chimpanzee.

In conclusion,

It can be inferred that life began at the bottom of the ocean as single-celled organisms and evolved to what we have now.

Thanks for reading

References for further reading: Ref1, Ref2, Ref3, Ref4