How did life begin?
A simple question to read but is not easily answered and understood. Primarily because there will be no actual verification of any theory due to the fact that it happened billions of years ago. For you, how did life on earth begin? How did you exist? Why did you exist? Who/What made it possible? What is the beginning of all beginnings?
The origin of life remains a mystery to biologist and even to us, ordinary people. Theories range from creation by divine forces, to seeding of life on Earth through events originating from outer space until theory of spontaneous origin is largely tested.
However, regardless of the theories explained it is still you who can decide what is acceptable for you. At the very least, here are the three possibilities that have been either supported or refuted by many scientists.
1. Special Creation
This long-lasting creationist theory assumes that a supernatural being such as divine God is responsible for creating life. Perpetuated by the teachings of major religions, thus it is the most widely known and accepted.
Some accepted this theory, from its biblical account of creation as the actual events that lead to formation of the world and life as well. One example is that, the ever famous Noah’s Ark which is believed that the ark served as a reservoir for either the actual animals or genetic banks.
2. Panspermia
The theory of Panspermia suggest that life may have been carried to earth by beings of extraterrestrial origin. The earth is thought to be formed as an aggregate of meteorites, comets, and other heavenly bodies continually slamming against each other.
It is also thought that it could have carried life forms that thrived when the earth cooled down. As the study of the solar system has improved, the hypothesis that life is not restricted to earth has gained momentum.
Like the presence of liquid water underneath ice in Europa, a satellite of Jupiter which may be capable of supporting life. The planet Mars which has earth-like conditions that could have been conducive to spawn life. Further, bacteria-like fossils found in rocks from Mars, collected in 1984 in Antarctica, lends this theory to credence.
3. Spontaneous Origin
Also known as the biogeochemical theory, this is accepted by most scientists as it is the theory that can be thoroughly tested for confirmation. It refers to the phenomenon that life evolved from inorganic and inanimate matter.
as it had been seen in early times. Image Source
During 1920s, scientists Aleksander Oparin and John Haldane independently proposed that the Earth’s primitive atmosphere was conducive for the creation of organic molecules. These molecules were packaged into ancestral cell-like structures called protobionts (precursors of life) such as coacervates, microspheres and liposomes. This theory came to be known as the OPARIN-HALDANE Hypothesis , and serves as basis for the Miller-Urey experiment.
The Miller-Urey Experiment
In the 1950's, biochemists Stanley Miller and Harold Urey, conducted an experiment which demonstrated that several organic compounds could be formed spontaneously by simulating the conditions of Earth's early atmosphere.
They designed an apparatus which held a mix of gases similar to those found in Earth's early atmosphere over a pool of water, representing Earth's early ocean. Electrodes delivered an electric current, simulating lightning, into the gas-filled chamber.
After allowing the experiment to run for one week, they analyzed the contents of the liquid pool. They found that several organic amino acids had formed spontaneously from inorganic raw materials. These molecules collected together in the pool of water to form coacervates.
Their experiments, along with considerable geological, biological, and chemical evidence, lends support to the theory that the first life forms arose spontaneously through naturally occuring chemical reactions.
However, there are still many skeptics of this theory who remain unconvinced. British astrophysicist, Fred Hoyle, compares the likelihood of life appearing on Earth by chemical reactions "as equivalent to the possibility that a tornado sweeping through a junkyard might assemble a Boeing 747 from the materials therein".
Any of the three possibilities might be true.
However, only the last two theories are testable.
Fossil records indicated that life in the form of primitive bacteria
as early as 3.5 billions of years ago.
Where did life begin?
The Earth’s formation commencing 4.6 billion years ago is hypothesized to be a continuous slamming of rubble against one another, eventually aggregating into one massive structure.
The change in the Earth’s early condition, even though it was still incredibly hot, that gave birth to life. Have you been curious about where life begins at? Well, here are the hypothesis on where exactly the first signs of life on Earth originated:
1. Primitive Earth’s atmosphere
The Earth’s first atmosphere is composed of hot hydrogen gas alone, while the Earth’s second atmosphere is suggested to be a mix of water, carbon monoxide, carbon dioxide, nitrogen, ammonia, and methane where the appearance of the first seas were marked and is characterized by constant intense lightning, volcanic activity, and ultraviolet radiation.
2. Frozen ocean
Life is hypothetically originated under a frozen ocean. Nearly any planet that contains water potentially hold life as it is the perfect solvent that can allow biochemical reactions to occur. Early Earth may have had frozen oceans containing water and carbon.
3. Underneath Earth’s crust
Early Earth had extremely violent and harsh conditions characterized by intense volcanic activity. Life may have been formed as a product of energy from intense volcanic activity, with metallic molecules such as iron and nickel minerals acting as catalysts to fuse gases ejected by eruptions.
4. Clay on Earth’s crust
Life may have resulted from silicate surfaces. Clays has positive charges to attract organic molecules and exclude water, hence will act as a catalytic surface to produce more complex molecules.
5. Vents in deep sea
A popular hypothesis in which Genetic profiling revealed that theoretical ancestors of prokaryotes are closest to the profiles of bacteria that still thrive today in deep-sea vents.
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REFERENCES: Click the link |Earth and Life Science by REFRAN TOLENTINO GENUINO
There may be a lot of possibilities and hypotheses in this world.
The important is, we know how to conserve and preserve everything that we don't own.
However, with the advancement of technologies combined with powerful minds
of our people, sooner or later, everything will be answered.
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