The origin and early evolution of photosynthesis

The Oparin-Urey-Miller hypothesis of the chemical origin of life states that carbon and nitrogen on the primordial earth were highly reduced and that energy sources such as lightning converted these simple molecules to amino acids, purines, and other biochemical building blocks. These reactions require reduced carbon (Stribling and Miller, 1987). However, evidence from geochemistry increasingly favors carbon dioxide as the predominant form of carbon on the early earth. Thus a dilemma arises.