What Is The “Primordial Soup” Theory?

By Antonia Čirjak on March 11 2020 in Answer

The “Primordial Soup” theory is a theory that offers an alternate way to look at the origins of life on Earth.
The “Primordial Soup” theory is a theory that offers an alternate way to look at the origins of life on Earth.
  • The “Primordial Soup” theory claims that organic life was created from inorganic materials.
  • According to this theory, molecules in the atmosphere were energized by lightning, which created a “soup” in which amino acids were created, which then led to the creation of proteins.
  • Scientists tested this theory in the famous Miller-Urey experiment.

The “Primordial Soup” theory is a theory that offers an alternate way to look at the origins of life on Earth. The theory suggests that all life began in a pond or an ocean almost four million years ago. It states that a combination of various chemicals from the atmosphere and a form of energy is responsible for the creation of amino acids.

These amino acids are the foundation of proteins, which then evolved into living creatures. This theory was conceived by the Russian chemist Alexander Oparin, and English scientist John Burdon Sanderson Haldane in the early 20th century. They both developed a similar theory independently of each other.

The Creation Of Life On Earth

The “Primordial Soup” theory claims that the basis of all life started from a single molecule that was formed in the atmosphere. This molecule was energized by lightning and the rain from the atmosphere, which then created an “organic soup.” In this soup, the birth of the first organisms happened.

These organisms were heterotrophs, meaning they were not able to produce their food. Instead, they had to consume other organisms to survive. This was their only source of energy before photosynthesis. Through mutation, these organisms would then become autotrophs. However, now we have evidence that the first organisms were autotrophs.

The atmosphere of our planet was a reducing atmosphere millions of years ago, which means that there was almost no oxygen in it. Several gases are believed to have existed then, most commonly hydrogen, methane, and ammonia. When these gases mixed, essential elements would get created.

Some of the more notable ones are carbon and nitrogen. These elements could then be rearranged and make amino acids. It is known that amino acids are the building blocks of proteins, and many scientists believed that these primitive ingredients combined into the first organic molecules on our planet.

The Miller-Urey Experiment

An experiment from 1953 tried to prove this theory. American scientists Harold Urey and Stanley Miller tried combining the atmospheric gases in the exact amount believed to have been present in the Earth’s atmosphere millions of years ago. They also simulated an ocean inside of a closed space, using a special apparatus.

They used electric sparks to simulate lightning shocks, and they managed to create various organic combinations, including amino acids. What was more surprising, a large amount of carbon in the “fake” atmosphere turned into organic building blocks. This experiment seemingly managed to prove that the “Primordial Soup” theory was real.

However, many scientists have since found various issues with this experiment. For once, in the experiment, the lightning strikes were constant, while they do not appear so in the atmosphere. This means that the creation of amino acids did not happen as fast as it did in the experiment. This does not directly disprove the theory, but it shows that the experiment was not proof enough, since the process would have possibly lasted much longer.

Another issue is that it was found out that the atmosphere was not the same back then, as Miller and Urey simulated in the experiment. The amount of methane they used was wrong, and that severely reduces carbon in the atmosphere, which means that the organic molecules would form even harder. Still, this experiment, and the theory itself, are considered significant and extremely relevant.

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