The Equatorial Engine (EE) hypothesis proposes that the equatorial ocean of an early aqua-dominated Earth may have functioned as a planetary-scale system for concentrating and cycling prebiotic chemistry. During the Hadean and early Archean eons, extensive global oceans, intense solar forcing at low latitudes, and abundant floating pumice produced by volcanism may have created conditions favourable for large-scale chemical transport and concentration. Exploratory particle-transport simulations in simplified aqua-planet circulation models suggest that equatorial circulation systems can produce persistent zones of convergence and retention of floating material. Rather than identifying a single localized origin-of-life environment, the Equatorial Engine hypothesis proposes a distributed planetary system capable of sustaining large-scale prebiotic chemistry across the early ocean.

This manuscript presents a conceptual hypothesis intended to stimulate further modelling, laboratory experiments, and geological investigation into planetary-scale processes influencing prebiotic chemistry.