What’s in a name? That which we call a rose

By any other word would smell as sweet.

- Romeo and Juliet, (II, ii, 47-48)

Juliet may have been on to something here, lamenting Romeo’s familial allegiances while he skulks below her in the shadows. “What’s Montague?” she says, “it is nor hand, nor foot, nor arm, nor face, nor any other part belonging to a man” (II, ii, 45-46). This attitude, a willingness to look past her family’s prejudices and see the man that Romeo is, beyond his name, makes Juliet a great romantic.

Romeo and Juliet by Konstantin Makovsky, c1980.

But it would’ve made her an awful scientist.

Good science, and by extension good scientific writing, occludes confusion by being tediously specific. Scientific writing tends to be devoid of metaphor, simile, or any other forms of figurative language. Most scientists are even a little bit afraid of a good evocative verb (although we’re allowed to write ‘masticate’ instead of ‘chew’, which is sort-of fun). The purpose of this fuss-budget writing, other than to make scientific papers blindingly boring to read, is to avoid confusion. A sentence should have only one meaning and not be open to interpretation.

So when it comes to science, everything is in a name. Every species on Earth has a name, which applies to it, and to no other species. These names all take on the same, two-part structure: Genus species. The first part of the name gives the genus to which the species belongs, for example Homo. The second part of the name identifies a specific species within that genus, for example sapiens. Combined together, this two-part name grants a unique identifying tag to every species, which is universally identifiable by scientists regardless of their native language. For example, Homo sapiens – humans.

This system, called ‘binomial nomenclature’, allows scientists to communicate about specific species. This is important because many different species have the same common name. As an example, lets consider Juliet’s rose. Roses, as we think of them, are not a species but a genus – the genus Rosa. All roses are identified by the traits that they share. Some of these are obvious (sickle-shaped thorns, the number of petals, and the type of fruit – a rosehip), and some of them are the sorts of thing that only excite botanists (alternate pinnate leaves with serrated leaflets and basal stipules. Yawn.). Those are traits shared by all roses in the genus Rosa.

But within that genus, there are at least 100 species of rose.

What type of rose was Juliet talking about? The play is set in Verona, in Northern Italy, so maybe Juliet was speaking about Rosa gallica, the French Rose. It was (and remains today) a widely cultivated species native to southern Europe. She was probably not referring to Rosa californica, native to, obviously, California. In Romeo and Juliet it doesn’t really matter. But scientists need to be able to determine exactly which species their colleagues are referring to – a problem that took over a thousand years to be solved.

Rosa gallica. Juliet’s rose of choice?

Beginning with Aristotle, natural historians struggled to label species in a way that was both descriptive and simple. The problem of the roses arose (hah) quickly; it wasn’t long before the people categorizing organisms realized that the same local name was used in many different places to refer to many different species. So scientists gave up on the idea of trying to be simple, and focused on being descriptive: species were given polynomial names that became increasingly more complex as more species were discovered.

Unique or strange species would be easy to name. For example, if we were to make up a descriptive name for the aye-aye, we could call it “long-fingered nocturnal lemur”. The animal is strange enough, and shares few enough traits with other species, that it is easy to hone in on a unique identifier. But that becomes more difficult when considering species that have fewer uncommon characteristics. Consider the hoary plantain, a small flower native to Western Europe. The hoary plantain illustrates both the problem of common names – it is in no way related to plantains, the banana-type vegetable that is a staple food item throughout the Tropics – and the problems that arose with polynomial names.

The hoary plantain looks a lot like just about every other small flower in Western Europe. Finding a unique identifier is extremely difficult. So in the days before binomial nomenclature, the hoary plantain was identified using an absurdly long and complex polynomial name: Plantago foliis ovato-lanceolatus pubescentibus, spica cylindrica, scapo tereti. Meaning, of course, “Plantain with pubescent ovate-lanceolate leaves, a cylindric spike and a terete scape”. The need for these complex names made classifying an ever-growing number of species virtually impossible.

The hoary plantain. No one’s flower of choice.

And then along came Carl Linnaeus.

Carl, who later got carried away with his own brilliance and Latinized his name to Carolus, was a Swedish botanist who revolutionized biology and invented modern taxonomy (the classification of species). He grew up in Sweden, and lived most of his life there, teaching botany during the week, and rampaging through the countryside collecting plants and animals in his spare time. (I’ve seen the field kit he used to collect samples; it looks like a portable version of Frankenstein’s lab). He lived abroad between 1735 and 1738, before returning home to Sweden for the rest of his life. But it was while he was away from Sweden and living in Amsterdam that Linnaeus made his first major contribution to science.

A young Linnaeus in plant-collecting mode.

Linnaeus was a popular lecturer and a dedicated teacher, and like many scientists, a bit fussy. The polynomial system of names frustrated him: it was inefficient and inaccurate. In his travels around Sweden, he had begun to develop a new way of categorizing plants by subdividing them into categories based on shared physical characteristics. On one of these trips, he found the jawbone of a small animal and experienced a revelation: the same categorization could be applied to animals too, based on number and structure of teeth.

The British; a species unto themselves.

In Amsterdam, Linnaeus began compiling these categorizations into a book, the Systema Naturae. He listed the species of animal and plants he was familiar with alongside their complex, polynomial names. Then, beside each name, he wrote a simple binomial name – one generic term (the genus), and one specific (the species). These he then lumped into higher categories according to their physical characteristics. The first edition of Systema Naturea, published using a loan from a friend in 1735, was only 12 pages long.

But it was a hit. The simple way of classifying animals, and the strict consistency of Linnaeus’s naming, became instantly popular in the scientific community. Scientists, students, and natural historians fanned out across the globe, sending Linnaeus samples of plants and animals to be included in his naming scheme. When the 10^th edition of Systema Naturae was released in 1758, Linnaeus had classified over 7000 species of plant and over 4000 species of animal, and invented the hierarchical system of organization that biologists still use today: kingdom, phylum, class, order, family, genus, species.

The influential 10th edition of Systema Naturae.

Under Linnaeus’s scheme, the hoary plantain became Plantago media, and life got a whole lot simpler. Scientific names today are the best place for researchers to actually indulge in a little creativity. Sometimes they’re clever (Apopyllus now, a species of sac spider found on Curacao), sometimes they’re juvenile (Batrachuperus longdongensis, a salamander), and sometimes they’re oxymoronic (Mammuthus exilis, the pygmy mammoth), but they’re always unique to one individual species.

Batrachuperus longdongensis, in the flesh. Credit: AG Urodela

Binomial nomenclature allowed scientists to begin categorizing, and from there understanding, the organization of life. It is one of the most important inventions in the history of science. But we should be glad Shakespeare never heard of it. “That which we call a Rosa gallica by any other word would smell as sweet” isn’t very poetic.

Neil Griffin