<P> The evolution of photosynthesis refers to the origin and subsequent evolution of photosynthesis, the process by which light energy synthesizes sugars from carbon dioxide, releasing oxygen as a waste product . The process of photosynthesis was discovered by Jan Ingenhousz, a Dutch - born British physician and scientist, first publishing about it in 1779 . </P> <P> The first photosynthetic organisms probably evolved early in the evolutionary history of life and most likely used reducing agents such as hydrogen or electrons, rather than water . There are three major metabolic pathways by which photosynthesis is carried out: C photosynthesis, C photosynthesis, and CAM photosynthesis. C photosynthesis is the oldest and most common form . C3 is a plant that uses the calvin cycle for the initial steps that incorporate CO2 into organic material . C4 is a plant that prefaces the calvin cycle with reactions that incorporate CO2 into four - carbon compounds . CAM is a plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions . C4 and CAM Plants have special adaptations that save water . </P>

How did the evolution of photosynthesis help change the earth