When Did Photosynthesis Emerge On Earth? By David Des Marais

The article “ When Did Photosynthesis Emerge on Earth?” was written by the principal investigator of the Ames Research Center team of the NASA Astrobiology Institute, David Des Marais. His experience has led him to publish more than 160 technical articles and chapters on many research topics such as the biogeochemical carbon cycle and the early evolution of the Earth and its biosphere. In this particular article, Des Marais establishes that life dates back to 3800 years ago and that not only its great antiquity easily illustrates how life can arise on a habitable planet, but also how it can definitely be a sign of the challenges that involves becoming familiar with our predecessors. In order to provide an accurate time of evolutionary innovations and its environmental context, the author sustains that geological records and biological information complement each other as a key-lock. “The geologic record offers the absolute timing of evolutionary innovations and their environmental context, while the living biochemical record can reveal the sequence of development of key pathways and biomolecules.” Before photosynthesis, life consisted of single-celled microbes whose power source was obtained from chemicals, such as sulfur, iron and methane. A group of microbes developed the ability to …show more content…
A strong evidence of this is found in the rusty iron-rich layers in geological stratum corresponding to the period mentioned before. Oceans had changed its color to green while oxygen was reacting with minerals. When the reactions stopped, oxygen could finally enter the atmosphere. Even though each cell only produced a small amount of oxygen, the combined metabolism of many cells during a vast period transformed the atmosphere to what is today. It allowed cells to colonize the surface of the ocean and ultimately the dry