The oxygenation of Earth’s surface fundamentally reshaped global biogeochemical cycles, and surface oxygen levels have played a critical role in the origin and diversification of metazoans. Stable thallium (Tl) isotope systematics are mechanistically linked to the burial of manganese (Mn) oxides, making the system an effective redox proxy to track free oxygen (O2) levels in the ocean. The Mesoarchean and mid Proterozoic are two critical periods of time in geologic history for the evolution of microbial and complex life.