In this episode, Martin Van Kranendonk lays out a convincing case for life on Earth going back to at least 3.48 billion years ago. To find evidence for very ancient life, we need to look at rocks that have been largely undisturbed over billions of years of Earth history. Such rocks have been found in the Pilbara region of northwest Australia. As explained in the podcast, the 3.48-billion-year-old (Ga) rocks of the Pilbara's Dresser Formation contain exceptionally well-preserved features that show unmistakeable physical and chemical signatures of life. While older 3.7 Ga rocks in west Greenland may also prove to have harbored life, the Dresser Formation rocks represent the oldest widely accepted evidence for life on Earth. Martin Van Kranendonk has devoted his long and prolific research career to the study of the early Earth. One major theme of his work has been to use detailed mapping and lab research to develop geological models for the environments of Earth’s oldest fossils. This has helped establish the biological origin of many ancient fossils. His recent work on a newly discovered find of exceptionally well-preserved 3.5-billion-year-old sedimentary rocks in the Pilbara Craton of Western Australia has provided the strongest evidence to date that structures of this great age were produced by the earliest forms of life. Martin Van Kranendonk is a Professor in the School of Biological, Earth, & Environmental Sciences at the University of New South Wales in Sydney.