It has been suggested that methanethiol played at least three key roles in the origin and early evolution of life: as (1) an ingredient of methyl thioacetate (see Introduction), (2) a metal chelator for delivering hydrothermally derived metals to the deep ocean , and (3) a nutrient for microbial chemoautotrophic activities . The first possibility can be realized in H2-rich alkaline hydrothermal vent environments with the geoelectrochemical mechanism , in which the strongly negative electric potentials generated by H2 oxidation (H2 → 2H + + 2e -) facilitate CO2-to-CO reduction and methanethiol carbonylation at the vent-ocean interface with NiS partially electroreduced to metal (NiS_PERM) working as the catalyst . This methanethiol conversion efficiently proceeds even at room temperature and neutral pH, facilitating the accumulation of methyl thioacetate while suppressing the decomposition.