Do kings play chess on fine green silk?

If you’re not scratching your head right now, you’re probably flashing back to ninth-grade biology class. That’s because this peculiar question is a mnemonic device for the taxonomic ranks of biology: domain, kingdom, phylum, class, order, family, genus, species.

More than just a name game, taxonomy is "the science of discovering, describing, and classifying species or groups of species,” according to The American Society of Plant Taxonomists and the Society of Systematic Biologists.¹ It is, in effect, the science of the tree of life, the language we use to illuminate the branching paths that bring us all back to the same shared starting point: the evolutionary origin of life.

Not to suggest the taxonomists have it all figured out. People have been trying to understand the order of the natural world for as long as we’ve existed, and while we’ve certainly come a long way, taxonomy isn’t a fixed system. Like the very species it studies, it finds itself in constant evolution — and that’s a good thing.

The First (Plant) Family

The very urge to categorize is baked into our brains, which suggests we human beings have been taxonomists since the start.² The earliest natural classification system captured by the historical record is that of the Greek philosopher, Aristotle. Like any scholar, Aristotle was a product of his time, which means his approach to taxonomy can look a little screwy to modern eyes. Among the key criteria in Aristotle’s system were the supposed nature of a species’s soul (humans had rational souls, while plants’ were vegetative) and the species’s relationship to the classical elements of earth, water, air, and fire (dolphins were associated with air, snakes with water).³

For thousands of years, Aristotle’s theological-philosophical approach to taxonomy was the norm, but with the 16th-century onset of the Scientific Revolution (which we touched on in last month’s story about holism), scholars began to search for more rigorous, empirical methods of classification. They would find just that with the help of Pierre Magnol.⁴

Born in Montpellier, France, in 1638, Magnol was formally trained in medicine. He first took up botany because he felt a thorough knowledge of plant life would be useful to his practice as a physician. He carefully studied the flora of Montpellier and the surrounding regions, and thanks to his dedication and astute observations, he quickly became a renowned expert in the field. Botanists from far and wide sought to join Magnol on his scientific expeditions.⁵

In 1676, Magnol published Botanicum Monspeliense, a compendium of 1,354 plant species he had studied. In 1697, he published a catalogue of the plants in his own personally cultivated garden, Hortus regius Monspeliensis, which contained the first formal scientific descriptions of a number of plants, including Pyrenean honeysuckle and spiny cocklebur.⁶

Above all, Magnol’s greatest contribution to botany — and to the scientific world as a whole — was Prodromus historiae generalis plantarum. Published in 1689, Prodromus contains the first use of the term “family” as a grouping of plant (or animal) life.⁷ This was more than the introduction of a new term to the scientific vocabulary: Magnol’s family classifications relied on a much more sophisticated set of criteria than was customary at the time. While most botanists grouped plants together according to perceived similarities in their flowers and fruits, Magnol took into account the physical characteristics of every part of the plant. In doing so, he laid the groundwork for the more nuanced forms of taxonomy that would come later.⁸

It wasn’t until 1735 — 46 years after Magnol’s plant families — that the “father of modern taxonomy,” Swedish botanist Carl Linnaeus, would publish his groundbreaking work, System Natura, which includes a very early form of the same ranking system scientists use today.⁹

Two-hundred years before Charles Darwin, Magnol’s work also hinted at the possibility of evolution. As evolutionary ecologist Stephen Heard puts it, Magnol’s “organizational system was one of our first steps toward realizing that all plants, and all life on Earth, have a common evolutionary origin and shared evolutionary history. … This fact is the foundation of all modern biology.”¹⁰

Given how much Magnol contributed to botany, it’s fitting that the French botanist Charles Plumier named the magnolia genus of plants after him.¹¹ Like the man himself, Magnol’s namesake was a trailblazer: Magnolias constitute one of the oldest surviving plant genuses. Appearing in the fossil record even before bees did, the magnolia’s flowers are thought to have evolved to attract pollinating beetles instead.¹²

Although Magnol and Linneaus helped build the foundation for modern taxonomy, the system has evolved quite a bit since their time. For example, Linnaeus’s original system — which only included plant, animal, and the now discarded mineral kingdoms — didn’t quite know what to make of fungi, which seemed to occupy some strange space between plant and animal. Modern taxonomists now recognize that fungi are neither plant nor animal and need their own kingdom.¹³

Similarly, breakthroughs in genetics and our advanced understanding of evolution allow modern taxonomists to look beyond shared physical characteristics when analyzing the relationships between organisms. Now, many taxonomic trees are arranged according to shared ancestors, using an approach called “cladistics,” from the Greek word “κλάδος,” meaning “branch” — a reference to the branching nature of the tree of life.¹⁴

As this history of refinement suggests, taxonomy is not an exact science. In fact, not all taxonomists agree on the best approaches to the discipline, and scholars may use numerous variations on the taxonomic ranks depending on their methods. At its heart, taxonomy is really a system of curiosity — a way of uncovering the invisible threads that bind all life together. Unfortunately, however, it can sometimes have the opposite effect. As evolutionary biologist Carol Kaesuk Yoon argues in Naming Nature: The Clash Between Instinct and Science, taxonomy often seems to the average person to be less like a transcendental tree of life and more like a sterile pursuit best left to people in lab coats. “We are so used to someone else being in charge of the living world that we have begun not to even see the life around us,” she writes.¹⁵

But Yoon also thinks we can combat this by reopening space for what she calls the “human umwelt,” a German word meaning, loosely, the particular perspective an organism has of its environment. In Yoon’s view, humans have an innate, “thoroughly sensuous and wildly subjective” approach to ordering the natural world. Yoon advises us all to indulge in this approach more often — both for fun and to connect more meaningfully with nature.¹⁶

Yoon doesn’t think we should do away with modern scientific taxonomy entirely, but she does think we need to supplement it with a more immediate experience of nature. She even suggests going out into the world, finding an organism, and personally getting "a sense of it, its shape, color, size, feel, smell, [and] sound.”¹⁷

The Unscientific Approach to Science

“Science,” Yoon writes, “was neither the best nor the only valid way to order and name the living world. Instead, I realized that the ordering and naming of life was and always had been, at its heart, something much more democratic, subversive to the dominion of science even, and much more interesting.”¹⁸

In following Yoon’s advice, we might also want to give more credit to our folk taxonomies, the informal, culturally specific classification systems that spring up outside of science. Think, for example, of an English speaker’s tendency to use “bug” and “insect” interchangeably. That’s fine in folk taxonomy, but scientific taxonomy actually distinguishes between the two categories.

As it turns out, our folk taxonomies are more trustworthy than we might think. They may not have the seal of scientific approval, but they still uncover meaningful connections between the inhabitants of the world. In fact, a study of Tzetzal speakers in the Mexican municipality of Tenejapa found that the community’s informal classifications of mammal species in the region tracked relatively closely with mainstream scientific taxonomy. Of the 75 Tzetzal folk taxonomic terms analyzed, researchers found that 55 of them “correspond[ed] exactly to some taxon of the scientific system.”¹⁹

The takeaway here might just be to trust ourselves a little more. Sure, mainstream scientific taxonomy is a vital endeavor, but so are the personal relationships we have with the world categorized in that taxonomy.

In fact, taxonomy as we know it wouldn’t even exist without curious people who took it upon themselves to step outside and simply look a little more closely at the world around them. When Pierre Magnol discovered plant families, he wasn’t in a lab — he was out in his own garden, admiring up close and personally the very flowers he himself had cultivated.

— The Keap Team