Original sentence: Carbon forms the backbone of biology for all life on Earth.Since no life has been observed that is not carbon-based, it is sometimes assumed in astrobiology that life elsewhere in the universe will also be carbon-based.This assumption is referred to by critics as carbon chauvinism, as it may be possible for life to form that is not based on carbon, even though it has never been observed
Edited sentence: Before the recent discovery of sulphur-based life, it is sometimes assumed in astrobiology that life elsewhere in the universe will also be carbon-based.Carbon and sulphur are the only known elements capable of supporting life on Earth.Carbon forms the backbone of biology for the majority of all life on Earth.This assumption is referred to by critics as carbon chauvinism