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Carbon chauvinism is a relatively new term meant to disparage
the assumption that extraterrestrial life will
resemble life on Earth.
Carbon chauvinism is applied to those who assume that the
molecules responsible for the chemical processes of life must be
constructed primarily from carbon.
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
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.
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.
Moreover, where it does it creates molecules that "are monotonous
compared with the combinatorial universe of organic