Resumen de Dawn of the water eaters
Barras talks about the discovery of living representatives--bacteria. At its heart, photosynthesis is about harvesting the sun's energy. Plants use this energy to make food, by building chains of carbon from carbon dioxide. The process produces sugars that can be used as an energy source or to make more complex molecules, from proteins to DNA. But contrary to what one might expect, it does not necessarily produce oxygen. In fact many bacteria turn light and CO^sub 2^ into food without producing oxygen. What's more, recent discoveries suggest they have been doing so for nearly as long as there has been life on Earth
