The geological record provides an irreplaceable account of the joint history between the Earth and living organisms. Extant living organisms also contain in their phenotypes and most importantly in their genomes information about their history, and about the history of the Earth. In this review we explain how biologists attempt to extract this information and draw inferences about past history, using statistics, computer algorithms, and molecular biology. We show that inferred ancestral gene contents provide insights into ancient metabolisms, ancestral genome composition in bases or amino-acids provide information about ancient growth temperatures, and protein resurrection offers means to investigate the function of proteins long disappeared. All these inferences throw a new light on organism and Earth evolution. Their combination and the use of statistical models integrating both genomic and geologic histories hold great promises for unveiling more of the past 4 billion year history on Earth.