How did life originate? Probably one of the oldest and most important question for scientists all over the world, who have
proposed several theories based on different explanations trying to give a final result to the most polemic question.
5 of the most important Theories of the Origin of Life.
Creationism: interpretation inspired in religious creations. It's believed that every single living
being and the Earth was created by one or several divine beings or gods. This theory is based on
''God Masterpiece'', ''The Genesis'' a book where we can find a simple and non scientific but very
accepted hypothesis of how God created everything.
Creationism wasn't actually denied. Scientific theories are
the ones that opposed to Creationism along with not
believers.
Spontaneous generation: Aristotle postulated that living beings emerged from inert matter that creates a type of energy or force
capable to give life. He said that life could also be given when the four main elements get combined. He believed that insects, worms,
fishes and any other organism were created spontaneously with humidity and other elements.
To prove this theory Van Helmont created a experiment: placing a dirty cloth and
grains of wheat for twenty one days, which resulted in some rodents.
This Theory was actually accepted during many years until
Francesco Redi proved the contrary, with a experiment: by placing
meat in two three jars, one uncovered, the other one covered with
net that only allowed air to pass through and the other one
completely covered with a lid. After a few days the meat was rotten
and only the jar without a lid or the net was full of maggots, he concluded
that decay meat does not creates flies or any other organism.
Panspermia: ''Panspermia literally means seeds everywhere''. It's believed that there's ''seed'' of
life that exist all over the outer space and it suggest that life could have existed on another place
and moved to Earth.
Although Panspermia is the most accurate and accepted theory it
does not actually explains where does the seed come from or how
were they created. It just it says that life evolved elsewhere and
somehow an asteroid brought it to this planet.
Oparin Hypothesis: Aleksandr Oparin and John Haldane had a similar Theory of the Origin of life. Primitive atmosphere was supplied with
oxygen free and it was only presented combined with other elements, atmosphere was also supplied with radiation and abiotic elements that
combined together with minerals from the primitive oceans they created the first living organisms. Haldane talked about this as a big soup in the
ocean where different elements combined together created the first cells.
There's not fossils that proves that life evolved from the ocean.
Endosymbiothic theory : an eukaryotic cell appeared thanks to the symbiotic phenomenon and other
different bacterias. So a small cell was ingested by a bigger and more developed cell, but it wasn't digested so
that was how and eukaryotic cell was formed and it evolved into the first living being. This theory was proposed by Lynn Marguhs.
Opposition to Endosymbiotic Theory there's a pretty good argument againts it. Cells cannot survive
without their organelles, and Mitochondria and plastids contain introns that's a type of DNA that need to be transfer.