A Quest to Understand Life on Earth
In simpler times, it was the consensus that God created man. Then science happened, and there were questions about the origin of life that scientists have since been trying to find the answers to.
It is a compelling question. Put it in the context of the largely abiotic nature of the known universe, and life becomes the biggest mystery to have intrigued the human mind. Despite all our technological prowess, we still can’t be sure whether the origin of life is some rare luck or whether it is a delicate piece of a puzzle spanning across the galaxy.
The technical term for this set of ideas about the origin of life is abiogenesis. The scientific community considers that life originated from simple organic compounds, and it evolved into the complex beings we see today.
But we do not know the exact mechanics of this process. The organic compound theory is the extent of what scientists agree upon. But beyond that, there are many theories defended by different communities in the scientific world.
New evidence and counter-evidence come up every day, moving the ball back-and-forth between the various schools of thought.
The study of abiogenesis is largely cross-disciplinary. It includes contributions by astrophysicists, biologists, geologists, and many other branches of science.
Yet, it is a difficult thing to deduce how life emerged on our planet. One of the reasons why such a vast community hasn’t been able to answer this question is because the conditions on earth today are different from the conditions when life first originated on the planet.
There have been many attempts to recreate the conditions with some success. The first of these was the Miller–Urey experiment. Though, it did not fully mimic the so-called primordial soup’, it was able to create simple amino acids out of naturally occurring chemicals.
However, it is still unknown how these organic compounds came to form complex DNA and RNA. These are now commonly known to be the molecules responsible for carrying genes from parent to child.
Similarly, the ideas about the formation of cells are still mostly theoretical.
There are currently three major schools of thought about the origin of life. The first school says that the first lifelike characteristic to emerge was that of reproduction.
This theory draws from Darwinian ideas and the fact that reproduction is one of the fundamental characteristics of life.
The proponents of this theory accept that the first form comprised purely of RNA instead of DNA and proteins. This idea was proposed by Leslie Orgel, who believed that early signs of life had self-replicating RNA.
It was the first time a particular characteristic, namely reproduction, was suggested to have emerged before others and triggered the inception of this ‘turf war.’
The second school of thought says that before reproduction, the life form would need to have a boundary with the environment. This process is known as compartmentalization.
It focuses on the development of cells with walls or membranes. Alexander Oparin popularized this idea.
He proposed that coacervates were the ancestors of modern cells. These are microscopic droplets of organic molecules such as lipids held together by electrostatic forces.
It is known as the Oparin-Haldane hypothesis after Oparin and J. B. S. Haldane, who proposed a similar model independently.
The third is that of metabolism. Life, in its essence, consumes, stores, and uses energy for all processes. Thus, the theory argues that the ability to perform metabolism must’ve come first.
Wächtershäuser and Michael Russell advocated this idea, among others, who argued that all the life processes would require energy. And therefore, some form of metabolism must’ve existed in the original life forms.
All three doctrines have survived to the present day with bits of evidence coming from each of the groups. Modern-technology enabled further analysis of these ideas, and it is being pursued with a renewed interest.
The most ambitious of the current ideas is an all-inclusive theory. Everything emerged first. The argument is that instead of isolated steps that were classically thought of, life happened, with all the three phenomena taking place simultaneously.
John Sutherland proposed this radical new idea based on his work at the Laboratory of Molecular Biology (LMB) in Cambridge, UK.
The RNA first group was working on the challenge of demonstrating how nucleotides would have formed naturally on earth. Sunderland’s team put five simple molecules together through a series of reactions that produced two RNA nucleotides without sugars or bases.
While some viewed this as a success for the RNA group, Sunderland himself believed that there was more to it. He took inspiration from Jack Szostak, who was the first to propose a combination of replication-first and compartmentalization-first ideas.
The experiments regarding replication of the process of origin, until this point, controlled conditions and the chemical mixture to the things required to synthesize a particular substance. Sunderland argues that it was the combination of all these factors - the messy sludge of chemicals - that led to the emergence of life.
This year, there have been discoveries and studies supporting many contradicting ideas. Some say that life originated at the bottom of the ocean.
With every discovery, we feel that we are close to the answer, but when we give a closer look, we realize we’re far from it. Many new ideas are emerging, supporting previous ones, but there hasn’t been a single successful attempt at recreating life.
We might be able to demonstrate a process in lab conditions, but that doesn’t necessarily mean that is the way it happened.
The problem is that there are a lot of theories and not enough experimental evidence to back them. The truth is, we might never know how life happened.
Even so, the implications of this study are huge, and not just on a scientific level.
When Darwin first suggested that animals evolved from a common ancestor, he was ridiculed, and his ideas dismissed and mocked. Yet today, his work is more or less considered a fact.
The world today is more open to ideas, and yet questions like this are often challenging on many levels.
Knowing that the complex being called man evolved over billions of years from simple chemicals does not make it any less of a miracle.
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