Emergence and evolution of early life in the geological environment

Based on our current assumptions, life on Earth started long before 3.5 billion years ago, the age of the oldest (accepted) terrestrial fossils. The issue on how life emerged from a non-living world, however, is still waiting for a solution. Aside from the many ideas generated by theoretical speculations, however, the issue on origin and evolution of the primordial life can be addressed through some of the oldest environmental conditions still preserved on the terrestrial sedimentary record (and their alleged modern analogues), and other planetary bodies, especially Mars, where rovers, orbiters and spectrometers can deal with unaltered rocks much older than the oldest one preserved on our planet and, perhaps, finally able to reveal some evidence of life