ORIGIN OF LIFE

## What is Evolution?

Evolution mainly deals with the origin of life on earth. The conditions and the forms of life on earth were entirely different from what we see today. Everything evolved from one form to another for a better chance of survival.

Here, let us know in brief about the origin of life on earth.

The Origin of the Universe

Origin of life begins with the origin of the universe. The universe, an old vast and empty space comprising of galaxies, originated around 20 billion years ago. There was nothing but blackness filled with gas and dust. The Big Bang Theory is the most accepted theory regarding the origin of the planet earth and the existence of different life forms on it. According to this theory, the universe is a result of a massive explosion which occurred 20 billion years ago. Whether it is a hypothesis or a fact, a new universe was formed. The atmospheric condition after the explosion became more stable. The temperature reduced and gasses like hydrogen and helium formed which led to the formation of galaxies of today.

Later, after 10 billion years, the earth was formed which was covered by water vapor, methane, carbon dioxide, and ammonia. There was no atmosphere but only gasses and moisture. The powerful rays of the sun stimulated and hastened the evolution. By making and breaking of bonds between gas molecules, earth came out with a new face. After millions of years i.e., once earth atmosphere was stabled, the first life on earth came into existence (around 4 million years ago). There began the story of the origin of life on earth.

The Origin of Life

There were lots of hypothesis regarding the origin of life on earth. Certain experts suggested that life came from outer space as spores while another group explained that life came from a non-cellular component such as decaying matters like mud. The latter theory was known as the theory of spontaneous generation, which was discarded later.

In the year 1953, Oparin and Haldane suggested that life originated from non-living organic molecules like proteins and RNA. This was followed by the theory of chemical evolution which suggested that atmospheric conditions of earth led to the formation of organic molecules from inorganic molecules. Few scientists conducted experiments regarding the same. However, once the first life came into existence, they started to evolve in different ways and forms. This laid a stepping stone to the theory of evolution.

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