Mafic-ultramafic igneous rocks as a source of reactive phosphorus for the origin of life

Phosphite and pyrophosphate—reduced and polymerized forms of phosphorus—may have played a central role in prebiotic chemistry owing to their higher reactivity and solubility, yet their geological sources remain uncertain. Here we show that mafic–ultramafic rocks on the early Earth could have provided a sustained source of reactive phosphorus through seafloor weathering. Rock analyses from 15 localities reveal phosphite comprising up to 7%, 24%, 17%, and 0.6% of total phosphorus in olivine separates, peridotite, komatiite, and basalt, respectively, while pyrophosphate accounts for up to 5% and 0.4% in komatiite and basalt. Box-model calculations indicate phosphite concentrations reaching up to 1 µM in the deep ocean and up to 67 µM in lakes under low-UV conditions. We suggest that reactive phosphorus released from mafic–ultramafic rocks could have fuelled prebiotic phosphorylation and supplied phosphate to emerging life on Earth, a process that may also enhance the habitability of other planetary bodies.