Linnaean Hierarchy

The Linnaean Hierarchy

The great name in the biological taxonomy is the Swedish botanist Carl von Linné (1707-1778). He developed both a system for naming species and for organizing living beings. Linnaeus's system for naming species has not changed since the publication of 10th edition of Systema Naturae in 1758. Each species has a name in Latin composed of two distinct words (why it is known as the binomial nomenclature). The first word is capitalized and describes the genus of the species, the second the species itself. Both names are written in italic in texts. The genus is a noun and the species epithet is an adjective. Any citation of a species must include both names. All ranks above the species are capitalized but only the genus is italicized. All names must be unique and universal and should be kept stable.

"Linnaeus's scheme of arranging organisms is a hierarchical system of classification. The major categories, or taxa (sing. taxon) are given one of several standard taxonomic ranks to indicates the levels of similarities between all the members of the group. The system has been considerably expanded since Linnaeus and includes 7 mandatory ranks: in increasing level of similarities kingdom, phylum, class, order, family, genus and species. All species described must belong to at least 7 taxa , one at each of the mandatory level. Taxonomists have the option of subdivizing these 7 ranks into further taxa (superclass, subclass, superorder, suborder, subfamilies, etc.) for any particular group of organisms. Today, more than 30 taxonomic rank have official status and used in particularly large and complex groups such as insects." (Anonymous, 2003).

Kingdom (Animalia)

Phylum (Chordata)

Class (Mammalia)

Order (Primates)

Family (Hominidae)

Genus (Homo)

Species (Homo sapiens)

Linnaean Hierarchy

The first edition of Systema Naturae (1735) had only eleven pages. Linnaeus later published new editions, adding new plant and animal species and also changed the classification. In the 10th edition (1758), for example, he moved the whales from the fishes to the mammals. The final edition was the 13th edition from 1770 which comprised 3000 pages.

"Linnaeus' system was based mainly on flower parts, which tend to remain unchanged during the course of evolution. Although artificial, as Linnaeus himself recognized [artificial versus natural classification], such a system had the supreme merit of enabling students rapidly to place a plant in a named category. It came into use at a period when the richness of the world's vegetation was being discovered at a rate that outstripped more leisurely methods of investigation. So successful was his method in practice that its very ease of application proved to be the greatest obstacle to its replacement by the more natural systems that superseded it." (Salisbury, 1994-1999).

"His [ Linné's] artificial classification system, initially very popular, was replaced by the ’natural’ system, more slowly in botany than in zoology, and more slowly in England than in some other countries." (Stevens, 1998).

"Linnaeus’ ideas owe much to those of Cesalpino, and ultimately to Aristotelian thought. Logical division yields natural groupings only in a taxonomy of analysed entities, and Linnaeus realized that he did not have such knowledge of animals and plants; his claims for the results of the a priori reasoning he applied were modest. Stamens, although important in reproduction, were not a true fundamentum divisionis, hence classes and orders were the work of nature and art and were only partly natural. Indeed, Aristotle had argued that logical division was an inappropriate tool for the classification of organized beings. It is difficult to relate Linnaeus’ ideas of development directly to those of Aristotle, in which the male is usually the active element, shaping a passive female substance. However, Aristotle’s general teleological framework bears comparison with that of Linnaeus". (Stevens, 1998).

In 1774 Antoine-Laurent de Jussieu (1748-1836) exposes in his Genera plantarum secundum ordines naturales disposita, juxta methodum in horto Regio Parisiensi exaratum anno 1774 ("Genera of Plants Arranged According to Their Natural Orders, Based on the Method Devised in the Royal Garden in Paris in the Year 1774", published in 1789) his ideas of plant classification, used until now. Against Linné, Jussieu stressed the significance of the morphological organization of organisms.

Linné classified both animals, minerals and plants. Those three "kingdoms" are known today, for example, in the play "20 questions" (Wikipedia, 2006d).

Literature:

Anonymous [2003]. Classification, taxonomy and phylogeny of animals. Available:
http://web.archive.org/web/20030706235226/http://www.squ.edu.om/agr/OnlineCourses/Biol2020/Taxonomy/Taxonomy.html

Cain, A. J. (1995). Linnaeus’s natural and artificial arrangements of plants. Botanical Journal of the Linnean Society 117, 73-133. (With references on clarification of the structure of Linnaeus’ classifications).

Ereshefsky, M. (2000). The Poverty of the Linnaean Hierarchy: A Philosophical Study of Biological Taxonomy. Cambridge: Cambridge University Press.

Larson, J. L. (1971). Reason and Experience: The Representation of Natural Order in the Work of Carl von Linné. Berkeley, CA: University of California Press.

Lee, M. S. Y. (2003). Species concepts and species reality: salvaging a Linnaean rank. Journal of Evolutionary Biology, 16(2), 179-188.

Natural museums, Pre-Linneaean period, Linneaean period, Modern period

http://wfscnet.tamu.edu/courses/wfsc421/lecture03/index.htm

Pennisi, E. (2001). Linnaeus’s Last Stand. Science, 291, 2304–2307.

Salisbury, E. J. (1994-1999). Linnaeus, Carolus. IN: Encyclopædia Britannica.

Stafleu, F. A. (1971). Linnaeus and the Linnaeans: The Spreading of their Ideas in
Systematic Botany, 1735-1789. Utrecht: A. Oosthoek. (About the reception of Linnaeus’ ideas).

Stearn, W. T. (1959). The background to Linnaeus's contributions to the nomenclature and methods of systematic biology. Systematic Zoology, 8, 4-22.

Stevens, P. F. (1994). The Development of Biological Systematics: Antoine-Laurent de Jussieu, Nature, and the Natural System. New York: Columbia University Press. (A reevaluation of the history of biological systematics that discusses the formative years of the so-called natural system of classification in the eighteenth and nineteenth centuries. Shows how classifications came to be treated as conventions; systematic practice was not linked to clearly articulated theory; there was general confusion over the "shape" of nature; botany, elements of natural history, and systematics were conflated; and systematics took a position near the bottom of the hierarchy of sciences).

Stevens, P. F. (1998). Linnaeus, Carl von (1707-78). IN: Routledge Encyclopedia of Philosophy, Version 1.0, London: Routledge.

Stevens, P. F. (2001). Book review of ‘The poverty of the Linnaean hierarchy: A philosophical study of biological taxonomy’ (Ereshefsky, 2000). Journal of the history of Biology, 34(3), 600-602.

Stevens, P. F. (2006). An end to all things? - plants and their names. Australian Systematic Botany, 19(2), 115-133.

Stevens, P. F. & Cullen, S. P. (1990). Linnaeus, the Cortex-Medulla Theory, and the Key to his Understanding of Plant Form and Natural Relationships. Journal of the Arnold Arboretum, 71, 179-220. (Discuss how the cortex-medulla theory underpins much of Linnaeus’ work).

http://evolution.berkeley.edu/evolibrary/article/_0/history_05

Wikipedia. The free encyclopedia. (2006a). Carolus Linnaeus. http://en.wikipedia.org/wiki/Carolus_Linnaeus

Wikipedia. The free encyclopedia. (2006b). Scientific classification. http://en.wikipedia.org/wiki/Scientific_classification

Wikipedia. The free encyclopedia. (2006c). Systema Naturae. http://en.wikipedia.org/wiki/Systema_Naturae

Wikipedia. The free encyclopedia. (2006d). Twenty Questions. http://en.wikipedia.org/wiki/Twenty_questions

Wilkins, J. S. (2003). How to be a chaste species pluralist-realist: the origins of species modes and the synapomorphic species concept. Biology & Philosophy, 18(5), 621-638. http://www.springerlink.com/content/n4t3w63844134120/fulltext.pdf