Earliest microbes on earth and possible occurrence of stromatolites on Mars

The carbon isotope ratios in 3.8 Gyr old Isua metasediments in Greenland and convincing evidence of life in the form of cyanobacterial stromatolites and microfossils present in Western Australia and South Africa clearly indicate that photosynthetic life was present about 3.5 Gyr ago on the planet Earth, Three major types of microbes Archaea, Bacteria and Eucarya in evolutionary order have been recognised as the earliest microbes on Earth. The first life was a simple micro organism (the RNA world), Recent discovery of possible filamentous bacteria from Martian meteorite ALH 84001 and presence of polycyclic aromatic hydrocarbons (PAHs) by NASA scientists is quite significant. There is vast scope for future exobiological research on Martian biota and possible occurrence of fossil microbialites (stromatolites) on Mars, Stable isotopic fractionation study of Martian microbial carbonate sediments and the latest evidence for presence of liquid water on the surface of Mars will help in understanding the comparative early history of Origins of Life and evolution of biosphere on Earth and Mars.