Complex life, such as humans and animals, represents the most mysterious aspect of existence. Scientists still cannot fully figure out how life works and how it began to exist in the first place, and before anyone claims otherwise, remember this: nobody has ever been able to create life in the laboratory from scratch (cloning doesn’t count), not even a small bug. Isn’t that the best possible argument that scientists still cannot fully understand the wonders of life?
However, the good news is that the world is still looking for answers when it comes to understanding the origin of life on Earth, not to mention its evolution. There are over 8 million species on Earth, including plants, which means that understanding all of life’s wonders is surely pretty challenging. There are a few scientific theories that explain how life might have begun on Earth, but none of them is fully reliable.
Panspermia
Panspermia proposes that the vital components for life may have their origin elsewhere in the Universe, most probably in our own Solar System, and were then transported to our planet by comets or meteorites. If this theory is correct, it means that we are all aliens in some way, which means that NASA astronomers should stop looking tor aliens on other celestial bodies of the Solar System and look in the mirror instead.
Of course, you could say that the panspermia theory still doesn’t explain the origin of life – if the building blocks for life did indeed come from other cosmic objects, how did it form there? Those who propose this theory don’t seem to know the answer to that question.
RNA World Hypothesis
In the RNA World hypothesis, life may have started with RNA molecules that have been self-replicating. RNA has the capacity to both catalyze chemical reactions and carry genetic information. The idea is that in the early stages of life, RNA molecules play two important roles by catalyzing chemical reactions such as proteins and storing genetic information like DNA.
Clay
Some scientists propose that complex organic molecules that are necessary for the emergence of life may have formed on the surface of clay minerals. If this theory is correct, it means that the chemical properties that clay has could have facilitated the assembly of organic molecules.
Abiogenesis
Abiogenesis implies that a series of chemical reactions causes life to emerge from non-living matter. While nobody knows exactly how such a thing is possible, it is thought to involve the gradual formation of simple organic molecules such as nucleotides and amino acids, which were eventually able to lead to the formation of more complex structures such as RNA and proteins.
Hydrothermal vents
Hydrothermal vents from the ocean floor foster high-pressure and high-temperature environments. Some scientists claim that life may have their origin in those environments, which are rich in minerals and could provide a potential setting for the appearance of complex organic molecules.
When did life begin to exist on Earth?
While figuring out how life began on Earth is quite a difficult task, it seems that scientists are better at responding to when the first forms of life appeared in the first place. Due to fossil evidence, it seems that life existed on our planet at least 3.5 billion years ago. Fossilized remains of microorganisms from the Isua supracrustal Belt of Western Greenland have given the oldest evidence of life that is widely accepted by scientists.
Since we’re talking about scientific theories here that explain the origin of life on Earth, we automatically ruled out the idea of a divine being that could have created life. We don’t say that there’s no such thing as God. In fact, science, by definition, explores the physical reality, not any supernatural realm. This means that science doesn’t deny the existence of a supreme and supernatural being.
