In this video, I give a brief overview of the possible origins of life on earth, also known as Abiogenesis. This subject is widely debated and no theory is completely agreed upon within the academic community. Never the less, many theories are plausible so, let us have at look at the basic theories of Abiogenesis.
Abiogenesis is defined as the process of organic material, or life, arising from non-organic compounds. It involves the fields of chemistry, biology, geophysics and other sciences or combinations thereof, each providing their own unique insights into the dilemma. It is thought that by understanding the chemical relationships of life processes with their environment that the answer will be found.
Out of multiple mostly overlapping theories, the first question is where living compounds or its early precursors originally developed. Was it on earth or outside of its sphere of influence?Both theories have reasonable arguments, however, the main question remains, how inorganic compounds can become organic and under what conditions would it occur?
As for where it could have occurred:
The extraterrestrial origin of life, known as Panspermia, hypothesises that the early building blocks and even some microscopic forms of life itself can develop and survive in certain areas of space. For example in dust clouds where chemical synthesis is possible through ionizing radiation leading to chemical evolution. Therefore, it argues that life or its constituents are already abundant in space waiting for ideal circumstances to develop into more complex forms. It is thought that these compounds and lifeforms are carried to earth via meteoroids, asteroids, dust-fall, etc. Then it evolves further upon the earth.
The other models of Abiogenesis argue that life could have developed on earth over a long period of chemical and eventually biological evolution. There are multiple hypotheses as to where, when and exactly how this could have occurred.
The most prominent being the Clay hypothesis, "Deep Hot Biosphere" model, Thermal Vents hypothesis.
The Clay Hypothesis states that an abundant form of clay called, Montmorillonite acts as a catalyst in the production of RNA which would then lead to DNA. (Process of Polymerization). The "Deep Hot Biosphere" model argues that basic forms of life could have originated several kilometres underneath Earth's surface. Subsisting primarily off of sediment and hydrogen byproducts. More recent discoveries of microbial life deep within the earth lend more credibility to this theory.
The Thermal Vent hypothesis declares that the perfect chemical and environmental conditions for life to develop is found in thermal vents. These are underwater fissures that project geothermally heated water into the ocean from beneath the earth's surface. The conditions are said to provide energy for abiogenic synthesis by stimulating and promoting the energy storage potential of formed membranes.
There are many other theories of Abiogenesis, which include frozen origins, lighting strikes and multi-origin theories. However, the greatest mysteries remain in the chemical understanding of how abiotic can become biotic. Modern science has been able to produce a few arguably living things through artificial synthesis, but as of yet, it remains far from its goal. Thus, the exact answers have not been found and the debate goes on.