The newest scientific discoveries suggest that photosynthesis first evolved around 3 billion years ago, and it was performed by the cyanobacteria. The cyanobacteria managed to use the sunlight in order to produce sugars, and it was releasing oxygen as a waste. This lead to the Great Oxidation Event. Since the cyanobacteria started to release oxygen, the atmosphere of our planet started to rapidly change, and the amount of oxygen was increasing constantly. This lead to a situation where there was so much oxygen in the atmosphere that it cooled the Earth extremely till the point of the Earth becoming one large ice ball, and this almost ended all life on our planet.
