Why do scientists go to great lengths to describe and classify species, and why are many of the names so incredibly difficult to say?

We all have names for the plants, animals and fungi around us. We understand what a magpie, a sparrow or a kiwi is. Many of us might be able to tell the difference between a brown kiwi or a little spotted kiwi. The names that we use are often descriptive – brown or black, little or great – and this helps us to describe what we have seen to other people. We are able to tell friends that we have just seen a tūī or a red-billed gull and they will understand.

So why don’t scientists use these names?

Why do they use very long, complicated and often unpronounceable names? The main reason is to avoid confusion. The common name – the one that most of us know, such as brown kiwi – often refers to a number of different species that may all look alike but might live in different areas.

To be a separate species, two animals must not be able to produce a fertile offspring. For example, a horse and a donkey are quite similar and can reproduce, but the offspring (a hinny or a mule) is not fertile (it can’t breed), so we consider horses and donkeys to be separate species.

The same the world over

Scientists name new species using international guidelines such as the ICZN (International Code (IC) of Zoological Nomenclature), ICBN (IC of Botanical Nomenclature), ICNB (IC of Nomenclature of Bacteria) or ICTV (IC of Taxonomy of Viruses).

Each code has its own rules about what needs to be included in the new name and what words can be used. Scientists also have rules about how a name is written. The genus and species are written in italics – this helps the scientists know when the scientific name is being used. For example, the common name octopus is the same as the genus name Octopus. The italics helps us distinguish that we are talking about a particular genus rather than a common description. Also, scientists always put a capital letter for the genus and a small letter for the species – Octopus vulgaris. If the scientist wants to refer to more than one species, they will commonly use the abbreviation ‘spp.’, which refers to all the species within the genus – Octopus spp.

Why is the name always in Latin?

Latin is the historical language of scholars and has been in use since Linnaeus first published his book on the systematic naming of plants, and because Latin is not in widespread use anymore, it is not evolving as a language or changing over time.

Modern languages develop new words, and the meaning of existing words changes, which is a problem when precision is needed. When one scientist talks to another about Mus musculus (the common house mouse), there is no confusion with its computer counterpart.

Using Latin also allows scientists around the world to talk with each other. When civilisations evolved, different communities often had different names for the same species or the same names for different species of the florafauna and fungi in their area. Systematic naming ensures that one species has one name, no matter where in the world it can be found.

It’s all relative

The names given to species also provide information about the lineage. It is a bit like a family tree and shows how the organism is related to other species. People in many cultures, including Māori, have a formal introduction that starts with their own name and then lists back through their parents, grandparents, great-grandparents and so on. In the same way, a species name can be traced back through genus, family, order, class, phylum and kingdom (these steps are called divisions).

Nature of science

When scientists develop explanations about the world, they share data, information and explanations about phenomena they are trying to explain. Because scientists are communicating with other scientists, they need a common vocabulary. Scientists working in biosystematicsconservation and biosecurity must know what organisms they are talking about, so they use the same universal classification ideas.

At each step, the organism becomes less related to the other species in that division, so two species in the same genus will be more closely related than two species in the same phylum.

These classifications are continually being evaluated and updated as new information is discovered (for example, developments in DNA technology), with many well known species being reclassified into a new genus or family to make sure they remain with their closest relatives.

Published 30 April 2009