This work puts forward an evolutionary scenario that satisfies the known constraints
by proposing that life on Earth emerged, powered by UV-rich solar radiation,
at photosynthetically active porous edifices made of precipitated zinc
sulfide (ZnS) similar to those found around modern deep-sea hydrothermal
vents. Under the high pressure of the primeval, carbon dioxide-dominated
atmosphere ZnS could precipitate at the surface of the first continents, within
reach of solar light.