Planet Earth was formed some 4,6 billion years ago. In the beginning, the Earth was an extremely hot celestial body. It was the target of continuous meteorite showers, and it had high levels of volcanic activity.

As the Earth cooled down, the steam produced by volcanic activity condensed into rain, which in turn created the oceans. A solid lithosphere and a gaseous atmosphere were also formed on Earth at this time.

The early atmosphere of Earth was different from what it is today. It contained water vapor, carbon dioxide, nitrogen, carbon monoxide, and poisonous gases. However, it did not contain oxygen in its free form. As a result of this, there was no ozone layer to protect the Earth from ultraviolet radiation. The living organisms of today would find it extremely difficult to thrive in the conditions of young planet Earth.

In the picture on the right, you can see a laboratory experiment created by the young student Steven Miller. This experiment was used to study the birth of amino acid in the imagined conditions of early Earth. The experiment proved beyond question that chemical evolution was possible in the conditions of early planet Earth.

There are various theories and assumptions about the early stages of life on Earth. Life is supposed to have emerged in stages. At first, the atmosphere contained only simple substances, which were combined into more complex substances as the result of lighting storms and meteorite showers. This is how elements important to life, such as amino acids and nucleic acids (DNA and RNA), were originally formed.

Chemical evolution was followed by biological evolution, that is, the evolution of the first living organisms.