Ancient volcanic rocks on the early Earth provided a steady supply of reactive phosphorus needed to build the first living cells. Scientists long thought early life required rare meteorites to deliver reactive phosphorus because common crustal minerals dissolve poorly in water. Natural weathering of mantle and volcanic rocks broke mineral bonds and released soluble phosphorus forms directly into prebiotic oceans.
Seafloor water seeped into iron-rich and magnesium-rich rocks, reacting with the mineral crystals. This chemical erosion dissolved trapped phosphite and pyrophosphate molecules like sugar washing out of hard candy. The dissolved compounds flowed into surrounding ocean basins and shallow lakes without breaking down immediately. In lakes with low ultraviolet light exposure, these molecules accumulated into dense chemical reservoirs.
A research team analyzed mafic and ultramafic rock specimens collected from fifteen different geological locations. Laboratory extraction revealed phosphite accounted for twenty-four percent of phosphorus in peridotite, seventeen percent in komatiite, seven percent in olivine separates, and zero point six percent in basalt. A box model showed that phosphite concentrations could reach one micromolar across deep seawater and sixty-seven micromolar inside surface lakes.
Researchers conclude that seafloor weathering provided a sustainable geological source of reactive phosphorus to drive prebiotic chemical reactions. This continuous rock weathering mechanism could also generate the chemical ingredients for life on other planetary bodies with similar volcanic geology.