Carbon chauvinism is a relatively new term meant to disparage the assumption that extraterrestrial life will resemble life on Earth.
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Carbon chauvinism is applied to those who assume that the molecules responsible for the chemical processes of life must be constructed primarily from carbon.[1] It suggests that human beings, as carbon-based life forms who have never encountered any life that has evolved outside the earth’s environment, may find it difficult to envision radically different biochemistries. The term was used as early as 1973, when Carl Sagan described it and other human chauvinisms that limit imagination of possible extraterrestrial life in his Cosmic Connection.[2]
In a 1999 Reason magazine article discussing the theory of a fine-tuned universe, Kenneth Silber quotes astrophysicist Victor J. Stenger using the term:
| “ | There is no good reason, says Stenger, to "assume that there's only one kind of life possible" - we know far too little about life in our own universe, let alone "other" universes, to reach such a conclusion. Stenger denounces as "carbon chauvinism" the assumption that life requires carbon; other chemical elements, such as silicon, can also form molecules of considerable complexity. Indeed, Stenger ventures, it is "molecular chauvinism" to assume that molecules are required at all; in a universe with different properties, atomic nuclei or other structures might assemble in totally unfamiliar ways.[3] | ” |
Carbon has unique features that make it suitable for life possessed by no other atom. Only two atoms, carbon and silicon, can create molecules that are sufficiently large enough to carry biological information. However, carbon, unlike silicon has the important property that it can form chemical bonds with diverse types of other atoms and so create the chemical versatility needed to enable the chemical reactions needed for biology such as metabolism. Atoms creating organic functional groups with carbon include hydrogen, oxygen, nitrogen, phosphorus, sulfur, and diverse metals, such as iron, magnesium, and zinc. The only alternative, silicon, interacts with very few other types of atoms.[4] Moreover, where it does it creates molecules that "are monotonous compared with the combinatorial universe of organic macromolecules."[4]
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