Taxonomy (biology)

For the science of classifying living things, see alpha taxonomy.

Taxonomy is the practice and science of classification. The word comes from the Greek τάξις, taxis, 'order' + νόμος, nomos, 'law' or 'science'. Taxonomies, which are composed of taxonomic units known as taxa (singular taxon), are frequently hierarchical in structure, commonly displaying parent-child relationships.

Applications

Originally the term taxonomy only referred to the science of classifying living organisms (now known as alpha taxonomy); however, the term is now applied in a wider, more general sense and now may refer to a classification of things, as well as to the principles underlying such a classification.

Almost anything, animate objects, inanimate objects, places, concepts, and events, may be classified according to some taxonomic scheme.

The term taxonomy may also apply to relationship schemes other than parent-child hierarchies, such as network structures. Other taxonomies may include single children with multi-parents, for example, "Car" might appear with both parents "Vehicle" and "Steel Mechanisms"; to some however, this merely means that 'car' is part of several different taxonomies.

A taxonomy might also be a simple organization of objects into groups, or even an alphabetical list. In current usage within "Knowledge Management", taxonomies are seen as slightly less broad than ontologies.

Mathematically, a hierarchical taxonomy is a tree structure of classifications for a given set of objects. It is also named Containment hierarchy. At the top of this structure is a single classification, the root node, that applies to all objects. Nodes below this root are more specific classifications that apply to subsets of the total set of classified objects. So for instance, in common schemes of scientific classification of organisms, the root is called "Organism" followed by nodes for the ranks: Domain, Kingdom, Phylum, Class, etc. (more details below).

Taxonomy and mental classification

Some have argued that the human mind naturally organizes its knowledge of the world into such systems. This view is often based on the epistemology of Immanuel Kant. Anthropologists have observed that taxonomies are generally embedded in local cultural and social systems, and serve various social functions. Perhaps the most well-known and influential study of folk taxonomies is Émile Durkheim's The Elementary Forms of Religious Life. The theories of Kant and Durkheim also influenced Claude Lévi-Strauss, the founder of anthropological structuralism. Lévi-Strauss wrote two important books on taxonomies, Totemism and The Savage Mind.

Various taxonomies

In alpha taxonomy, as the scientific classification of organisms, the system includes the root called "Organism" (as this applies to all living things, it is implied rather than stated explicitly), followed by the ranks: Domain, Kingdom, Phylum (plural, phyla), Class, Order, Family, Genus, and Species, with over 40 various other ranks sometimes inserted, such as subphylum, superorder, subfamily, subtribe, or subspecies to handle complex groups such as insects (more at: scientific classification or Linnaean taxonomy).

In cladistic taxonomy (or cladism or cladistics), life forms or living organisms can be classified by clades, which are based on evolutionary grouping by ancestoral traits. By using clades as the criteria for separation, cladistic taxonomy, using cladograms, can categorize species into unranked groups (groupings where "rank" terms like Class, Order, Family, etc., are not necessarily specified as they are in Linnean Taxonomy).

In numerical taxonomy or taximetrics, the field of solving or best-fitting of numerical equations that characterize all measurable quantities of a set of objects is called cluster analysis.

Non-scientific taxonomy

Other taxonomies, such as those analyzed by Durkheim and Lévi-Strauss, are sometimes called folk taxonomies to distinguish them from scientific taxonomies that claim to be disembedded from social relations and thus objective and universal.

Baraminology, a creationist alternative to cladistics, is a system that emphasizes reproductive isolation to delineate clear baramins (sometimes, "holobaramins)" of living things. The baramins are then grouped into levels of polybaramins based on similarity and degree of common design. These polybaramins can be identified as families, orders, divisions, and so on. Baraminologists often regard mammals as a separate class from other vertebrates.

The neologism folksonomy should not be confused with "folk taxonomy" (though it is obviously a contraction of the two words). Those who support scientific taxonomies have recently criticized folksonomies by dubbing them "fauxonomies" (French word "faux" means "false").

The phrase "enterprise taxonomy" is used in business to describe a very limited form of taxonomy used only within one organization. An example would be a certain method of classifying trees as "Type A", "Type B" and "Type C" used only by a certain lumber company for categorising log shipments.

See also

• Bloom's Taxonomy
• Celestial Emporium of Benevolent Recognition, a fictional Chinese encyclopedia with an "impossible" taxonomic scheme.
• Cladistics, the most prominent of several forms of phylogenetic systematics
• Folksonomy
• History of plant systematics
• Jean-Baptiste Lamarck
• Carolus Linnaeus, the father of modern taxonomy
• Knowledge representation
• Linnaean taxonomy
• Nosology
• Ontology
• Ontology (computer science)
• Scientific classification
• Set
• Systematics

External links

• Wikispecies Main Page
• Integrated Taxonomic Information System
• Taxonomy Browser of National Center for Biotechnology Information