Where did the origin of life come from? This fundamental question has not yet been completely resolved. Although many speculations and theories have been described, it is still not satisfactory for experts to answer the origin of life on this earth.
However, these theories are still worthy of discussion and debate. Many biologists, chemists and even astronomers are trying to find out the origin of life on this Earth.
Theories About the Origin of Life
a. Theory of Creation (The Creation Theory)
The first theory is the theory of creation. This theory states that life on Earth, especially humans, animals and plants was created by God. From the initial process of creation until now, the Earth has had an unchanging form.
b. Theory of the State of the Earth that Always Remains Stationary
The second theory of the origin of life is less acceptable, because it assumes that the earth and all living species on it have no origin.
c. Cosmozoa
Theory This theory states that the approximate origin of life on Earth comes from outer space. Mainly due to the fall of meteors and comets to Earth which contain a lot of simple organic compounds and then become the seeds of life.
Examples of these organic compounds include cyanogen or hydrocyanic acid. On the basis of this theory, perhaps Earth is not the only planet that has life.
d. Abiogenesis
Theory This theory began when a Dutch researcher named Antonie van Leeuwenhoek discovered microscopic bodies moving from a drop of straw soaked water that were observed through his homemade microscope.
This theory is almost the same as the Abiogenesis Theory expressed by Aristotle. The theory of abiogenesis has another name for spontaneous generation.
This theory reveals that the origin of life comes from non-living things. However, the theory of spontaneous generation faces many challenges.
One of them is the proof by Francesco Redi. He boils two pieces of meat that are still fresh, to educate his intention so that the meat is sterile.
The cooked meat is put in two different glass jars. The first jar is left open, while the second jar is tightly closed.
The first jar was infested with many flies, while the second jar was protected from flies. As a result, in the first jar there were lots of fly larvae, while in the second jar there were no fly larvae.
The conclusion of this experiment is that the larvae in the first jar came from flies that perched in the jar and then laid their eggs on the meat.
Meanwhile, in the second jar, no fly larvae were found, because the mother flies were unable to lay eggs in the jar because it was tightly closed.
Francesco Redi's experiment was later refined by an Italian researcher named Lazzaro Spallanzani. He did experiments with broth. He prepared three tubes filled with broth.
In the first broth, the mouth of the tube is left open. In the second tube, the mouth of the tube is also left open, but the broth is brought to a boil. While the third tube, the mouth of the tube is tightly closed with an additional layer of wax.
The tubes were then left for 7 days. After 7 days have passed, then in the tube with the mouth of the tube open, the broth in it looks cloudy. While in a closed tube, the broth is still clear.
The conclusion of this experiment proves that bacteria do not just appear spontaneously.
However, bacteria arise from bacterial spores from the outside air that enter and grow in the broth. This further weakens the theory of the origin of life abiogenesis.
e. Biogenesis Theory
Although Spallanzani's experiment received much appreciation, many supporters of the theory of Aristotle and Antonie van Leeuwenhoek revealed the weakness of the experiment.
One of them is the absence of contact with outside air for the third jar. The weakness of Spallanzani's experiment was later successfully refined by Louis Pasteur, a French microbiologist and biochemist.
He did an experiment using a pipe shaped like a swan's neck. This allows bacteria to still be in contact with the outside air and vice versa.
After a few days, it turned out that the results of the experiment were almost the same as those of Spallanzani's.
Louis Pasteur's experiment at the same time subverts the theory of abiogenesis which is still firmly held as the basis for the origin of life in society.
f. Biochemical Evolution Theory or Modern Biological
Theory Modern Biological reveals that the origin of life stems from chemical reactions that produce amino acids, where these substances are the basis for the formation of every living cell.
The main elements of amino acids are C, H, N and O. C comes from CH4, H comes from H2, N comes from NH3 and O comes from H2O.
Where the atmosphere contains a lot of these compounds. This theory explains that these compounds are then exposed to electric sparks and form amino acids.
Two modern biologists who put forward this theory are Harold Urey and Oparin. Harold Urey, an American chemist revealed a theory that life began in the oceans and then evolved to land.
To prove Harold Urey's hypothesis, Stanley Miller, a student at the University of Chicago, made a glass tube-like device with various fittings for inserting amino acid-forming gases.
The tool is also equipped with electrodes that function as a power source. His experiments proved to be able to form amino acid compounds.
Chemical Evolution
Stanley Miller tries to simulate what Earth's atmosphere was like when it was in primeval conditions on a laboratory scale. He put various gases such as H2, CH4, H2O and NH3 and water into the tools he made.
The water is heated so that it evaporates and mixes with the added gas. Then added high-voltage electricity which is simulated as lightning.
It turns out that a reaction occurs, and simple compounds such as amino acids, ribose and adenine are formed.
Evolutionary Biology
The next theory was presented by a Russian biologist named Alexander Oparin. Oparin said that the origin of life originated from the primitive atmosphere on Earth which underwent many chemical reactions, and produced organic compounds that make up cells.
This reaction is then in contact with the reactant energy in the form of ultraviolet radiation. The resulting organic compounds are known as primeval soups, where life begins. Piles of organic compounds will form lumps known as coacervates.
This heap is rich in organic materials which then form a lipid membrane, where we know that the cell membrane consists of lined lipids. This membrane then protects the coaservat that is in it.
However, scientifically, Oparin still has difficulty explaining how the mechanism of formation of coaservat into a cell and then produces heterotrophic organisms. That is an organism that can reproduce as well as take nutrients from the remaining ancient soup.
In addition, it is also very difficult to explain how the cell structure changes from non-living things to living things with extraordinary regularity of function.
The theory of the origin of life develops from time to time. Including the most recent theory expressed by Miller and Oparin. The theory of chemical evolution has been scientifically tested in the laboratory, although it has many challenges and has many weaknesses.
Meanwhile, the theory of biological evolution has not yet been scientifically proven through experiments.
Although there are many things that can be proven from the theories above, the basic origin of life has not been answered until now.
Since life is not just about the formation of the basic building blocks of amino acids, life is not just about the formation of cells and their replication. And life isn't just a simulation in a lab.
Furthermore, life is a matter of the structural arrangement of cells that interact and work together in a very orderly manner. Life is about the intelligence of living beings in seeking and obtaining food.
Life is also about the balance of nature that can run itself according to its function. And life is also about morals, ethics, aesthetics and human beliefs.
Science is also a part of life. Therefore, it seems that humans still need a very long time, so that they can prove scientifically about the true origin of life.