Theories on Origin of Life

Life on earth today is the result of billions of years of evolution. We can trace back our roots to the very first forms of life that emerged nearly 4 billion years ago. However, we have no idea how it started, because, the earth was a giant ball of molten rock and magma when it was formed. In essence, precursors to life had to start from inorganic materials such as hydrogen, carbon and methane. But this hypothesis wouldn’t be proved until Stanley Miller came along.

Stanley Miller Experiment

Earth, billions of years ago was a very hostile place that couldn’t support life. But Stanley hypothesized that life emerged exactly such a place by recreating the conditions found on ancient earth right here in his lab. He had collected the gases such as methane and carbon dioxide and other trace gases in a closed container and subjected the same to electricity. This simulated the lightning that was supposedly present billions of years ago. He left his experiment run for a while and later, came back to discover the most important aspect of life – amino acids. These substances are the key for all life on earth, and evolution may have taken a different route than the one present today.

It is hypothesized that the DNA Structure, which all of us share today is the result of amino acids forming bonds and creating new, specialized precursors to DNA. It is believed that RNA evolved prior to DNA, and was the primary vessel for heredity, storing and expressing all necessary information. However, the change from very basic, amino acids to very complex, self-replicating molecules couldn’t be explained. Stanley Miller’s experiment had no clear-cut answer to this question due to the sheer complexity of the scenario.

Panspermia Hypothesis

Other theories have emerged to fill the gaps that Miller’s experiment had left. One such theory is the Panspermia Hypothesis. It states that life on earth had originated from extra-terrestrial objects like asteroids and meteors. Current research has shown that these objects contain many molecules that may have the potential to kick-start life on earth. This “mechanism” means that life on earth originated from the stars. But the downfall to this evidence is the lack of evidence.

Discover more about the origins of life and other related topics right here on BYJU’s. Explore important concepts like Evolution, Anatomy, Cell definition, Digestion, Respiration etc. Alternatively, visit our YouTube channel to watch interesting and detailed videos on topics related to science.

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