Constancy of Species
See also Species.
(stub)
Aristotle: species
Linnaeus: fixity of species
USA National Center for Science Education report at Species, Kinds, and Evolution. A quote (with our internal links):
Creationists will often claim that they are not interested in the species level, though. Initially, creationism did require fixity of species. In the 1920s, when George McCready Price equated "species" to the biblical "kinds", he was forced, to allow for the Ark to carry "every kind", to raise the bar higher. Even this was not original. In the late 18th century, Buffon, Cuvier's predecessor, had suggested that there was a "first stock" from which all members of a kind had evolved, so that all cats evolved from an original animal, modified by geography and climate, for instance. So creationists themselves have a "vagueness problem" no less than evolutionary biology does. Life is vague. Certainly the creationist "kind", or "baramin", as they mangle the Hebrew for "created kind", is extremely elastic. Given that elasticity, the motivation for the inference that was made naturally during the 17th and 18th centuries that species do not evolve is undercut. If kinds are not exact in reproduction, why think that the Genesis account is enough to prohibit evolution? The answer is, of course, that biblical literalism is not the primary motivation here for opposition to evolution.
Compare Baraminology (evolution within the Biblical kinds) and Was the Flood followed by rapid evolution?