Understanding Evolution. The bacteria that changed the world - May, 2017 The make-up of Earth's atmosphere, once the domain of Earth science textbooks, has become an increasingly "hot" news topic in recent decades, as we struggle to curb global warming by limiting the carbon dioxide that human activity produces.
While the changes that humanity has wrought on the planet are dramatic, this isn’t the first time that one species has changed Earth’s atmosphere. Three billion years ago, there was no free oxygen in the atmosphere at all. Life was anaerobic, meaning that it did not need oxygen to live and grow. That all changed due to the evolution of Cyanobacteria, a group of single-celled, blue-green bacteria. National Center for Science Education - Defending the Teaching of Evolution in Public Schools. Teaching Evolution (flash)