Decoding the biogeochemical landscape of early life on Earth

Convincing traces of life – biosignatures – have been studied back to approximately 3.5 Ga, suggesting that microbial communities were already sophisticated in their metabolic machinery and distributed through multiple environmental settings. Furthermore, biocoenosis-level ecosystem complexity had evidently already been achieved by 3.5 Ga. Recent evidence from Palaeoarchaean to Neoarchaean (~3.6-2.5 Ga) rocks has further shed light on the co-evolution of Earth and Life: microbial diversity increases together with geological and environmental diversity, with substantial diversification at moments of global environmental revolution such as the development of widespread continental masses or the Great Oxygenation Event. This system of positive feedbacks is reminiscent of the Gaia Hypothesis.