Guide Note

Scientific classification, also called biological classification or taxonomy, is the system of organization and nomenclature used to define all life.¹

Fast Facts

1. Created by: Carl Linnaeus²
2. Origin: Systema Naturae (1735)³
3. Originally included mythological creatures²
4. Revised often to keep pace with discoveries

Biology and life science students may be called upon to recite the hierarchy of the Linnaean classification system from memory. These mnemonic devices may help to remember Kingdom, Phylum, Class, Order, Family, Genus and Species:

1. "Kids Prefer Cheese Over Fried Green Spinach"
2. "King Phillip Came Over For Great Spaghetti"
3. "King Philip Can Order Five Good Soups"

Since Linnaeus first published Systema Naturae, the relative relationship between different species has been determined by comparing visually obvious similarities.² For example, a primate is determined by the presence of a collarbone, forward facing eyes and opposable thumbs.⁴

The science of genetics enables scientists to use DNA to determine how evolutionarily close two species are.⁵ This reveals relationships that contradict established taxonomy. For example, a beech tree is more closely related to a cucumber than to a sycamore tree when relative genetic similarity is examined. Genetic similarity is used to show how recently two species shared a common ancestor.²

The Phylocode is a proposed attempt to adjust traditional scientific classification to reflect newly understood genetic relationships between living things.⁶