Examines how microbes shaped the biosphere and continue to influence life today. Investigates the origins of life on Earth, evidence for early microbial evolution, and the development of complex eukaryotic cells from prokaryotic ancestors. Emphasizes critical analysis of scientific data and ideas through discussion and peer collaboration. Topics include planetary conditions necessary for life, microbial metabolism and diversity, endosymbiotic theory, and the ongoing impact of microbes on Earth's ecosystems.