Life On Earth Evolved From ‘Redundant’ Chemical Systems
The earliest cells were unstable chemical systems that survived by combining a handful of shaky carbon-based assemblies together, researchers say. All life on Earth is based on carbon. To create living matter from carbon, organisms carry out chemical reactions such as photosynthesis to generate organic compounds from the carbon dioxide in the environment. These mechanisms, known as carbon fixation, make up the largest bridge between Earth’s nonliving chemistry and its life.
All organisms that fix carbon do so in one of six ways. It was unclear as to which of the six types came first, and how their development was linked with environmental and biological changes. Mapping the evolution of this vital chemistry would shed light on the roots of life on Earth. Now scientists have traced the six methods of carbon fixation seen in modern life back to what may have been a single ancestral form.