Billions of years ago a little blue-green algae has split the water molecule and released poison, the result of which became death and destruction on a massive scale. Talking about photosynthesis, oxygen and death anaerobic inhabitants of the Earth.

For the first time, geologists have found evidence of the most important evolutionary step, directly preceding the splitting of water by cyanobacteria. This is a unique snapshot of time before the world got its present appearance: with the advent of photosynthesis atmosphere was filled with oxygen, and thus was laid the road to the current diversity of life forms. This is the biggest change in the history of the biosphere.

Photosynthesis as a method of energy production by the body is possible in the presence of light and electron source. In our world this source is water, and oxygen becomes a by-product of the reaction. Photosynthesis appeared about 3.4 billion years ago, but there are no signs of formation of oxygen in those days. Most likely, ancient organisms instead of water used by hydrogen sulfide. Judging by oxidized minerals, photosynthesis in the form in which we know it today, emerged about 2.4 billion years ago.

How did it happen? To answer this question Woodward Fischer from the California Institute of technology (USA) and his colleagues studied the South African rocks, formed shortly before significant milestone. The analysis showed that, despite the formation of rocks in an oxygen-free conditions, the whole manganese is there in the oxidized form.

In the absence of atmospheric oxygen manganese needed some catalyst for oxidation. Scientists believe that a photosynthetic organism used manganese as a source of electrons. Remaining from these reactions unstable ions of manganese reacted with water and formed oxides.

Commentators welcomed the hypothesis, because it is consistent with the predictions of evolutionary theory. Oxidation of manganese still plays an important role in photosynthesis. In photosynthetic structures modern plants and algae are rich in manganese crystals that become a source of electrons. To fill the gap crystals away electrons from passing water molecules. It is this "robbery in broad daylight" breaks down the latest and produces the oxygen we breathe.

This complex process is likely to be very simple roots. In 2007, John Allen from Queen Mary College, University of London (UK) and William Martin from the Dusseldorf University (Germany) suggested the following scenario: in their opinion, modern photosynthesis was born, when the early cyanobacteria happened to be in the water environment, rich in manganese, and quickly adapted to a new source of electrons.

Later, as manganese - a relatively rare resource, whose reserves are not infinite, cyanobacteria have developed another strategy. They included manganese directly in their photosynthetic patterns and began to use the latter as batteries: once the electrons was over, they took them from the other, more abundant source, that is, water.

Therefore, what has found the group Mr. Fischer, is almost certainly a balance of activity primitive cyanobacteria.

The study results were presented at conference of the American geophysical Union.

Prepared according to NewScientist.