Initially living organisms used in organic foods primary ocean.As a byproduct of metabolism released into the atmosphere, accumulating carbon dioxide.However, stocks of "primordial soup" rather quickly been exhausted.
on to receive widespread and priority development of anaerobic organisms that can synthesize organic compounds from carbon dioxide and hydrogen, also be present in the atmosphere.Carbon dioxide are reduced, with the participation of hydrogen to methane.
The formation of methane releases energy that living organisms are used in their life processes.Once in the atmosphere, methane under the action of ultraviolet rays was converted to the organic compound returns to water.The concentration of methane in the co
mposition of the atmosphere then remained at the same level.
It was not until as long as there is enough in the atmosphere of hydrogen.Over time, stocks that were depleted gaseous substances and methane-producing bacteria lost their food source, not being able to convert carbon dioxide into methane.For energy and metabolism it needed a new form, which became photosynthesis.
first photosynthetic organisms do not produce oxygen.Later, there were organisms by photosynthesis which the atmosphere was saturated with oxygen.Gradually, the composition of Earth's atmosphere in which oxygen is occupied more and more space, has changed.
When oxygen appeared in the atmosphere only to living organisms that time he was a strong poison.Came the environmental crisis.Life had to disappear from the face of the Earth or to adapt to new conditions of finding a way to neutralize the poison.And such a mechanism has been found.
Then there living organisms began to use oxygen to generate energy.So there was a breath of oxygen.Through photosynthesis formed ozone shield, protecting the planet from the harmful ultraviolet light, allowing living things to learn subsequently the upper layers of water bodies and even go out on the land.Energy, which provided living organisms appeared the process of breathing, gave impetus for their further development and sophistication.