The Story about Oxygen and How it Got Here
The story about oxygen and all life that goes with it can owe their thanks to the oldest, still-living creature known as Cyanobacteria, or the blue-green algae. These little fellows were once the rulers of the world, the dominant species on the planet. Their success story, however, later proved to be their undoing, but in doing so, life as we know it happened.
These simple forms of life came into existence a long time ago, more than 3.5 billion years ago. They were the first to turn the sun’s rays directly into energy through photosynthesis. And in doing so, Cyanobacteria turned greenish due to chlorophyll, it multiplied like crazy and generated oxygen as a waste product of their “photosynthetic industry”. Up until this time, there was almost no free oxygen in the atmosphere, only trapped in water.
But time went on and these Cyanobacteria were slowly taking over the world’s oceans, also home to other life, but life of an anaerobic nature. In and of itself, this wasn’t a problem per se, but the thing is that oxygen is poisonous to these anaerobic forms of life. En masse, almost all life perished on Earth with the exception of the blue-green algae, who were thriving. This event later became known as the Great Oxygenation Event, 2.1 billion years ago.
With pretty much the whole planet at its disposal, Cyanobacteria continued on living out its life like it did for a billion years. But as oxygen was gathering in the air, two things began to happen. The oxygen started reacting with the methane to form CO2 and water. And since methane is a far better greenhouse gas than CO2, 25 times more so, in fact, the planet began to cool. And it cooled so much that it could not emerge out again for 300 million years.This unfortunate turn of events, known as the Huronian glaciation, brought the mighty Cyanobacteria to its knees, almost wiping it off the face of the planet. And all of it because of oxygen.
And this is when things began to change. Oxygen not only allowed for life as we know it today to evolve but also allowed for the formation of a multitude of minerals, forever changing even the Earth itself.
Their story stands to show what great and awesome things can be achieved by anything and anyone if they come together, all working with the same goal in mind. In this case, this was a waste-product, a gas, oxygen.