The emergence of oxygenic photosynthesis fundamentally transformed Earth’s surface environment and ultimately enabled atmospheric oxygenation and complex life. However, geological evidence suggests a substantial temporal gap between early biological carbon fixation and the later rise of stromatolites and atmospheric oxygenation during the Great Oxidation Event (GOE). Here, we propose a conceptual framework in which the long-term persistence of oxygenic photosynthesis and its later ecological expansion were spatially decoupled. We suggest that ultraviolet-attenuated environments preferentially supported the persistence of early oxygenic phototrophs, whereas warm, shallow, high-productivity environments promoted ecosystem-scale expansion. Iron redox buffering further constrained oxygen accumulation prior to the GOE. Within this framework, early carbon isotopic signatures reflect spatially restricted metabolic activity, whereas stromatolites record a later phase of ecological expansion. More broadly, this perspective suggests that environmental structure may regulate the ecological scaling of metabolic innovations in planetary biospheres.
S. Kato (Sun,) studied this question.