Aristotle sorted animals into bloodless and blooded on a Greek island
Long before Linnaeus, Aristotle spent time on Lesbos grouping creatures by traits such as live birth, egg-laying, four legs or warm bodies. He split animals into those with blood and those without, roughly our vertebrates and invertebrates, and some of his groupings, such as sharks and cetaceans, are still in use.
Taxonomy, from Greek words for arrangement and method, is the science of naming, defining and classifying living things by shared features. Organisms are placed in taxa arranged by rank: domain, kingdom, phylum, class, order, family, genus and species. Carl Linnaeus, the Swedish botanist, founded the ranked system still used today, though modern classification aims to mirror evolutionary relationships among living and extinct organisms.
Naming nature probably began with language itself, since telling poisonous plants from edible ones was a matter of survival. Egyptian wall paintings from around 1500 BC show medicinal plants, hinting at a basic classification. Aristotle's student Theophrastus described about 500 plants, and genera such as Crocus and Narcissus trace back to him. Medieval scholars largely kept Aristotle's framework, adding philosophical ideas like the great chain of being.
Scientific classification really took off in the 18th century with artificial systems based on chosen criteria, such as Linnaeus's scheme for sorting plants by their sexual organs. Natural systems followed, weighing many traits at once, from Jussieu in 1789 to de Candolle, who introduced the word taxonomy in 1813, and Bentham and Hooker. After Darwin's Origin of Species in 1859, phyletic systems from 1883 onward grouped organisms by descent. Cladistics arrived in the 1970s, accepting only groups that contain an ancestor and all its descendants, and molecular genetics now largely supports the older anatomical evidence.
The vocabulary is famously tangled. Taxonomy, systematics and phylogenetics overlap, and Europeans favour systematics while North Americans say taxonomy more often. In 1935 William Bertram Turrill coined alpha taxonomy for finding, describing and naming species, dreaming of an eventual omega taxonomy that would use every kind of evidence; Ernst Mayr later called the grouping of species into higher ranks beta taxonomy. Deciding how to define species themselves is known as the species problem.
Source: Taxonomy (biology)
