Early traces of Life

Characterizing plausible and reliable traces of microbial life is crucial to untangle the co-evolution of Earth and the biosphere. It may also inform on plausible conditions for life to emerge and evolve on a habitable planet or moon, and how to detect life beyond Earth. The origin of life (OoL) was probably possible since 4.3 billion years when Earth became habitable. Although the Earth rock record do not preserve the transition time from prebiotic molecules and vesicles to life, exploring early habitable environments on Mars and lab experiments in simulated conditions might provide some clues. Isotopic, biosedimentary, molecular and morphological traces of life suggest the early presence of prokaryotic communities for at least 3.4 billion years in diverse environments of the early Earth, implying an older LUCA, and thus an earlier OoL. Complex cells (eukaryotes) started to diversify by at least 1.8 billion years. However, these traces may in some cases also be produced and/or altered by abiotic processes or later contamination, leaving a controversy surrounding the earliest biological record. This talk will illustrate the challenges and evidence in identifying the early traces of life.