The Principles of Taxonomy

Early Taxonomy

• The 18th and 19th centuries witnessed a huge increase in scientific discovery, particularly in the fields of biology, botany and zoology. Naturalists traveled more widely and were constantly discovering new plants and animals. At the time, the naturalists didn't conceive of the idea that some animal and plants may be related through the evolutionary process, but they did use taxonomy to place everything into different categories according to their physical characteristics. In 1735, Swedish naturalist, Carolus Linnaeus, published " Systema Naturae." In it, he proposed a system of classification using "genus" and "species" as the categories.

Genus and Species

• In the hierarchical order, genus comes above species, and a genus may contain one or more species. This is known as "binomial" nomenclature, as an organism has a genus and species name. For example, a human is both "homo" and "sapiens." Homo is the genus, and sapiens is the species. Linnaeus also created categories above genus and species that were broader, such as "order." The order "primates" is an example as it includes monkeys, apes and humans. Linnaeus's classification clearly indicates that humans are animals.

Charles Darwin

• The Linnaean principles of taxonomy were changed by the work of Charles Darwin. His work on the principles of evolution and the process of natural selection showed that species did change over time. However, older scientists, like Linnaeus, had problems accepting that one species might evolve into another, although Linnaeus accepted that crossbreeding plants resulted in a new variety. Darwin's discoveries changed the approach to taxonomy, and classification started reflecting evolutionary relationships and the family trees of animals living today.

Modern Taxonomy

• In addition to showing how living species had common ancestors, modern taxonomy also shows how evolution uses a branching system to preserve life. The term for this is "cladistic" taxonomy. The branch system is called "adaptive radiation." This shows how animals, and plants, use the process of adaptation to survive in specific biomes and ecosystems. Developments in the principles of taxonomy are ongoing as biologists try to agree on new methods of classifying the upper orders in the system, such as "domain" and "kingdom."