Carbon Chauvinism

puddle thinking

Carbon chauvinism is a neologism meant to disparage the assumption that the chemical processes of hypothetical extraterrestrial life must be constructed primarily from carbon (organic compounds), as carbon’s chemical and thermodynamic properties render it far superior to all other elements.

The term was used as early as 1973, when scientist Carl Sagan described it and other human chauvinisms that limit imagination of possible extraterrestrial life. 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.

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.’

Like carbon, silicon can form four stable bonds with itself and other elements, and long chemical chains known as silane polymers, which are very similar to the hydrocarbons essential to life on Earth. Silicon is more reactive than carbon, which could make it optimal for extremely cold environments. However, silanes spontaneously burn in the presence of oxygen, so an oxygen atmosphere would be deadly to any silicon-based life, and water as a solvent would be equally deadly for the same reason. So, any environment with the potential for silicon-based life would have to be very cold, devoid of oxygen and water, but with another compatible solvent, such as liquid methane or a methyl compound to exhibit polymer activity.

The concise answer of science is that the chronicle of life on Earth refers to facts strictly connected to the cosmic physics and chemistry. Then, life on Earth is not dominated by eventuality, but life has been determined by the fundamental physical constants of the universe. The emergence of life on our planet obeyed to the universal physico-chemical laws and occurred like a natural and basic process.

Scientists observe that all life on Earth is carbon-based and they have not ruled out other forms of life, but there is currently no empirical data to support other forms, such as life based on silicon. The apparent lack of silane polymers and the abundance of carbon in meteorites would suggest that carbon-based life is much more probable than silicon-based life.


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