Earliest evidence for life on Earth: an Australian perspective

Australia is home to some of Earth's best-preserved early Archean rocks. Of particular interest in relation to the origin and evolution of life is the Pilbara Craton of Western Australia, containing one of Earth's oldest and least metamorphosed volcano-sedimentary successions. Over the past decade a number of new claims for Earth's earliest life have come out of these rocks, aided by significant advances in stratigraphic correlation and radiometric dating within this craton. This contribution provides an up-to-date summary of the evidence for life in Pilbara rocks > 3000 Ma in age. Potential indicators of life in these rocks include microfossils, trace fossils, stromatolites, biofilms (aggregates of cells and associated extra-cellular substances that have enveloped or colonised a substrate) and microscopic sulfide minerals with distinctive sulfur isotope signatures from normal marine, marginal marine and hydrothermal settings. This shows that Australia contains the most diverse and arguably the most critically evaluated evidence for life on our planet prior to 3000 Ma.