An oxygen atmosphere
For centuries, microbes were the only thing that could be found on Earth. However, everything changed when cyanobacteria evolved at least 2.4 billion years ago. But why are these life forms so important to the history of our planet?

Cyanobacteria helped create the oxygen all modern-day life forms breathe. These microscopic organisms are Earth’s first photo-synthesizers and transformed the world by forcing microbes to evolve into more complex life forms.






