Redox reactions played an important role in shaping the conditions that enabled the emergence of life on the early Earth, but how these relate to specific environmental conditions and whether they led to heterotroph or autotroph organisms remains a matter of debate. In this Review, the authors summarize and discuss evidence reconciling dominant theories — from the redox nature of the Hadean atmosphere and the presence of conditions that could have supported both heterotrophs and chemoautotrophs, to the transport of organic compounds that could have led to the emergence of life in multiple local environments.