Taxonomy is the science of naming and classifying organisms on the basis of their evolutionary relationships. With well over a million described animals, there must be a consistent and organized system for cataloging all of these species in a manner that correctly reflects their evolutionary relationships. Such a system was first proposed by Carlolus Linnaeus (a Swedish botanist) in his
Systema Naturae published in 1756. It requires that each organism be given a unique, Latin (the universal language of those times) binomial, which is called a species. For example
Homo sapiens is the binomial for humans. Remember, a species is a binomial, which means that it is not one word - the genus is
Homo, the species is Homo sapiens (i.e., the species epithet is never used alone)! Note that because the binomial is written in a foreign language it must be placed in
italics or underlined! Also note that the genus is a noun and Capitalized, while the species epithet (i.e.
sapiens) is usually a descriptive adjective. Sometimes, however, it is a name that honors a biologist. For example,
Rana blairi (the plains leopard frog) was named in honor of the famous amphibian biologist W.F. Blair.