Life on Earth Begins Over 3 Billion Yearsback over time, evolving from elementary microbes to incredibly complex organisms. But how did life on our planet emerge from a "primeval broth" into something as complex as Homo Sapiens? One of the theories suggests a “shocking” beginning, another idea contradicts it, the third one scares, the fourth one turns everything upside down. So where is the truth? Let's try to at least a little understand one of the most difficult questions of humanity, the answer to which the best minds have been looking for for millennia.
How did life come about?
Electrical sparks can generateamino acids and sugars from an atmosphere saturated with water, methane, ammonia and hydrogen, as was shown in the famous Miller-Yuri experiment, published in 1953. The results suggest that Lightning may have helped create the key building blocks of life on Earth in the early days of its existence.
The fact is that complex molecules canform over millions of years. Although subsequent studies showed that there was actually very little hydrogen in the Earth’s early atmosphere, scientists suggested that volcanic clouds in the “primeval” atmosphere could contain methane, ammonia and hydrogen were also filled with lightning.
The first molecules of life could also meet inclay, according to an idea developed by organic chemist Alexander Graham Cairns-Smith of the University of Glasgow in Scotland, according to Live Science. These surfaces could not only concentrate organic compounds together, but also help organize them into patterns, like our genes do. Recall that the main role of DNA is to store information about how other molecules should be arranged. Genetic sequences in DNA are essentially instructions on how amino acids should be located in proteins.
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Cold and DNA molecules
Ice may have covered Earth’s oceans 3 billionyears ago, since in those days, the brightness of the Sun was several times dimmer. Researchers believe that a thick layer of ice can protect fragile organic compounds on the seabed from ultraviolet radiation and destruction due to asteroid impacts. Understanding the origin of life may include unraveling the mystery of DNA formation: if DNA is needed for the formation of proteins, how could they form without each other?
The answer may be the RNA hypothesis, which performs several functions in organisms, including acting as on / off switch for some genes. Notably, RNA is also capable ofcatalyze their own "reproduction" and, in general, these macromolecules are capable of full-fledged chemical evolution. Thus, it is possible that evolving, the first RNA molecules discovered a way to synthesize the first protein tools, and then “discover” for themselves DNA double helix is an ideal carrier of hereditary information.
Read more about RNA and whether it canThe answer to the question of how life appeared, read in our material. The question remains how the RNA got here. Although some scientists believe that the molecule could spontaneously arise on Earth, others note that this is extremely unlikely.
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Life came to Earth from space
Perhaps life in general did not originate on Earth, butwas brought here from somewhere else from other stellar systems - this hypothesis is known as the panspermia hypothesis. Panspermia says that planets regularly exchange material with each other - for example, stones from Mars regularly fall to Earth and several Martian meteorites are known to science. Some researchers suggest that it was meteorites that brought to our planet the microbes that are potentially necessary for the origin of life. Some researchers have gone even further and point to comets from other stellar systems, for example, to Oumuamua, which, in turn, may turn out to be a space iceberg.
However, even if this concept were true,the question of how life was born on Earth invariably grows into the question of how life was born in other stellar worlds. In fact, our world is so insane that it may turn out to be one of the many realities, parallel universes, computer simulations, holograms and everything that we still can’t think of. Do you agree? We will wait for the answer here!