The moon forming impact converted the early Earth into a sphere covered in magma oceans that converted all carbon from accretion to CO2 and expelled it to the atmosphere. All water was converted to steam in the atmosphere, when it rained out it interacted with iron minerals in the crust to form H2 through a geochemical process called serpentinization. In the redox reaction between H2 and CO2, the equilibrium lies on the side of reduced carbon compounds. In modern origins theories, this redox reaction gave rise to the first organic chemical networks from which the core of microbial physiology in the first free-living cells arose. The first cells were prokaryotes and likely similar to modern acetogens and methanogens in their physiology (anaerobic chemolithoautotrophs using the acetyl-CoA pathway in carbon and energy metabolism). Fermentations, anaerobic respirations and anoxygenic photosynthesis followed, with oxygen-producing photosynthesis arising roughly 2.5 billion years ago. Eukaryotes arose about 1.5 billion years ago through endosymbiotic origin of mitochondria, plastids arose about 1.2 billion years ago from endosymbiotic cyanobacteria. Research at the HHU deals with these phases of life’s history.