Early Life: Evolution on the PreCambrian Earth, Second Edition offers an informative and compelling analysis of microbial evolution, often overlooked as the opening chapter of life's history. With this long-awaited new edition, Lynn Margulis and Michael Dolan integrate new discoveries from the past two decades, such as the enormous contribution of molecular biology, especially the accumulation of protein and DNA sequence information upon which the Woese three-domain system is based. Yet the prokaryotic-eukaryotic distinction remains the largest evolutionary discontinuity in life on Earth. Are the well-formed filaments found so recently in the Warrawoona Series of northwestern Australia really evidence of the oldest life on the planet?

Do the fossils found in the great Gunflint Iron Formation of Ontario tell that bacteria were instrumental in the accumulation of the most important iron reserves in the world?

These questions are not solved here, but they are raised for students, scientists, and general readers interested in the most basic evolution and its consequences. No special scientific background is required of the reader, only a lively interest.