What is Binomial Nomenclature?

Binomial nomenclature is the system used to identify all organisms on Earth, from elephants to algae. A binomial or scientific name identifies an organism by its genus and species, ensuring that everyone understands which organism is under discussion. Binomial nomenclature fits within the larger framework of taxonomy, the science of categorizing living organisms and assigning traits to them to understand the links and differences between them. The scientific name of an organism could be considered its definitive name, with scientific names being understood by scientists all over the world.

You may also hear scientific names being referred to as “Latin names,” in a reference to the heavy use of Latin in taxonomy. However, it is also common to see Latinized names, typically honoring the person who discovered the organization, or the region in which it was discovered; for example, Branta canadensis is the Canadian Goose. Greek is also used in scientific names, often in a jumble with Latin which brings some classical scholars to tears.

The system of binomial nomenclature was developed by Carolus Linnaeus, an 18th century scientist who attempted to codify the natural world with a taxonomic system. Various taxonomic systems had been used before this point, but Linnaeus established a flexible, easy to use system which caught on rapidly. Taxonomy was actually largely undisciplined until the 19th century, when people began to establish codes and organizations to oversee the field of taxonomy. When new organisms are discovered, they are reported to these organizations to ensure that the discovery is, in fact new, allowing a new name to be generated.

It can be helpful to know about some of the conventions used in regards to binomial nomenclature. For example, scientific names are always given with the genus capitalized, in italics, like this: Genus species. In scientific journals, credit is given to the person who discovered the organism in parentheses after the first listing of the scientific name, like this: Example animal (Jones, 1997). When the common name of an organism is given, the scientific name follows in parentheses, as in this example: “The Common Wombat (Vombatus ursinus) lives in Australia.”

The name of the genus is always spelled out, unless you mention an organism's scientific name more than once in a written document, in which case you may turn it into an initial, like this: “The biology of the Atlantic giant squid Architeuthis dux is not fully understood, but scientists hope that further studies of A. dux and its cousin, the Southern giant squid (A. sanctipauli) will yield more information on these fascinating creatures.” Common usages like "E. coli" are frowned upon by the conventions of binomial nomenclature, with scientists preferring to see Escherichia coli written out in any discussion of this fascinating bacterium.

In zoology, taxonomy is overseen by the International Commission on Zoological Nomenclature (ICZN), with equivalent bodies for botany, bacteria, and viruses. These groups all apply specific rules and codes to the scientific names they oversee, ensuring uniformity within their fields. Taxonomy is also by no means set in stone; organisms may move between genera, for example, as more information is gathered about them.