Carbon chauvinism
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Carbon chauvinism is a term meant to disparage the assumption that the molecules responsible for the mechanisms of life must be based on carbon. Since we have never encountered any life that has evolved outside the earth’s environment it is impossible to entirely discount this alternative biochemistry.[1] Those who study life on our planet, where all life is based on carbon, may find it difficult to envision radically different forms of biochemistry. Since we are in fact carbon-based life-forms, excluding other elements as the central atoms of life could be considered chauvinistic.[2]
The term may be criticized as inaccurate since chauvinism is usually defined as unreasonable belief in superiority. The belief described as carbon chauvinism is a belief that non-carbon based life is unlikely to exist, not a belief that such forms of life would be inferior if they did exist. Secondly, there is a strong basis for the belief that all life must use carbon as the central atom to construct the molecular structures that form all the complex mechanisms of life. From a chemical standpoint it is the only element that appears to have the right balance of stability and reactivity to form very complex molecular structures needed for cell machinery.[3] These structures include the cell membrane composed mainly of lipids that separate the cell interior from its surroundings, and DNA and RNA composed of nucleic acids for storage, transcription, and translation and of genetic data. An incredibly large and varied number of proteins composed of amino acids perform most all the other cellular functions including enzymes that catalyze chemical transformations. There are also a wide variety of small molecules that play a support role in regulation of biological systems and chemical communication between cells. All atoms other than carbon seem to have flaws that exclude their use in all these roles and no one has yet proposed a theory using another atom that would form all the cellular structures necessary. It is likely that life evolving in an environment isolated from ours would function with some significant differences to ours, such as the opposite chirality or different energy cycles, but it is difficult to see how any other atom could be used to build all these structures.
