Will the real taxonomy please stand up?

An imposter, focused on species identification, distracts from the real science of systematic biology

Until the real taxonomy reasserts itself as an independent, fundamental, curiosity-driven science, pursued on its own terms, practiced at its highest levels of excellence, and true to a mission distinct from that of other life sciences, it is in danger of becoming little more than a high-tech identification service for biology.  There is nothing inherently wrong with providing identifications, of course, along with insights into the relationships among species.  Such usefulness has been a hallmark of taxonomy from its very beginning.  But focusing on such limited, applied goals leads to very little knowledge of species themselves or the history by which they came to be.  It is the attributes of species, both novel and shared, and the sequence of transformations by which characters came to be, that makes species exploration most interesting, rewarding and valuable.

A long-running television program, To Tell the Truth, is a metaphor for taxonomy.  Molecular taxonomy, and other versions of taxonomy concerned primarily with identifying species, are imposters.  The real taxonomy is a fundamental, curiosity-driven science that seeks to discover, know, describe in detail, and discern relationships among species and clades; to compare and understand their attributes in the context of phylogenetic history; and to synthesize knowledge in an informative, predictive, phylogenetic classification.  Applied taxonomy is necessary, but not sufficient, for humankind’s age-old quest to understand its origins and the world it occupies.  It is time for the real taxonomy to stand up for its own mission, goals, theories and methods.  Systematics should always remain a reliable partner of other life sciences, making species identifiable along with knowledge about them and their relationships, but as a valuable by-product of its own research agenda.

Two factors are suppressing the real taxonomy and shifting resources to an applied, molecular, so-called taxonomy.  First is the immediate, legitimate and growing need to simply tell species apart so that environmental and conservation goals may be pursued.  And second, a combination of perceived modernity, technological sophistication of DNA sequencing, and prestige accompanying its association with biomedicine and a flood of money into molecular labs.  But, as Ed Wilson once said to me, molecular data does not receive more money because it is inherently better than morphology, it is seen as better because it receives more money.  It is difficult to promote traditional taxonomy against such headwinds, but unless we successfully do so we risk permanent ignorance of the diversity and history of life.  And we supply less, and less reliable, information to those seeking identifications.

This need not, and should not, be an either/or proposition.  We can have both a vibrant, basic systematics and efficient means to identify species.  The ideal is to have—as has been the case for centuries, and until recently—both.  Further, applied taxonomy is far more valuable when it is a by-product of, and backed up by, fundamental systematics.  From explicitly testable species- and relationship-hypotheses to the amount of information about species and clades, and the informativeness of names and classifications,  everyone is served best when systematics is supported to pursue its own aims with the best theories and methods, to remain committed to the mission that has guided it for centuries: the exploration and classification of the diversity of life at and above the species level, discovering, describing, making sense of, and organizing knowledge of species, their characters, and their relationships.

But limited funding, even more limited understanding, greed and hubris are in the process of derailing taxonomy, of reducing it to a minimally informative caricature of its former great self.  When chemistry knowledge is used to develop useful compounds, no one proposes leaving basic chemistry behind.  When the laws of physics enable the design of more aerodynamic automobiles, no one suggests that we abandon fundamental physics.  And as stars of the Milky Way are mapped, no one thinks it a good idea to turn our backs on the vision of astronomers to continue to explore and understand the universe.  Yet, meeting the immediate need to identify species, and the expediency of molecular data to that end, are accepted as a substitute for the intellectually rich, fundamental science of systematics and its inventory and exploration of the history of life.  The ultimate costs of ignoring basic taxonomy to science, society and the age-old quest to understand ourselves, the world around us, and their origins, are massive and irreversible.

Unlike other sciences, systematics done well requires comparative studies of morphology, along with all relevant sources of evidence.  When species go extinct unrepresented in museum collections, even when documented by DNA sequences, we become permanently ignorant of their morphology and burn the bridge it forms to the fossil record and ontogenetic developmental sequences.  As we confront a biosphere undergoing a mass extinction event, we have one, and only one, opportunity to explore, document and describe, as fully as possible, the diversity of species and clades.  Rather than seizing this amazing opportunity, we are degrading taxonomy into a rote set of procedures based on just one rather minimally informative source of data.  We owe it to ourselves and future generations to do what we alone can do:  to complete the inventory of species commenced by Linnaeus, the description of species long pursued by taxonomists, and the phylogenetic classification of as many species as possible.

A field guide that allows us to identify birds, but provides minimal information about them, is a poor substitute for the science of ornithology.  An identification guide to birds based exclusively or primarily on DNA, an even poorer one.  What makes the study of birds exciting are the incredible, unexpected, often amazingly novel or complex attributes observable among their thousands of kinds.  If penguins, parakeets and pigeons all looked identical, there would be little incentive to explore them, or the origins of their diverse forms.  No reason for birders to rise before dawn in the hope of catching a glimpse of a kind not seen before.  Ignorant of morphology, having no idea of what a bird or dinosaur looks like, their relationship to dinosaurs, based solely on DNA evidence (hypothetically assuming that were possible), would be nothing more than arbitrary information.  But learning the sequence of evolutionary transformations in morphology from dinosaur ancestors to modern birds make their study deeply intellectually satisfying.  Yes, DNA barcodes divorced from morphology might allow us to identify species, but to what end?  Robbed of knowledge of birds, including morphology, the ability to tell species apart is a vacuous goal.

Denied recognition, respect, research positions and funding, too many taxonomists are going along with the shift toward a molecular-based taxonomy.  They are guilty of surrender and complicity.  Some comply with this popular trend because they enjoy the pats on the back from colleagues and easily secured grants that come with prioritizing molecular data.  Others conform out of sheer desperation, compromising their own science’s mission, and subjugating its priorities, in order to find funding. 

Every taxonomist stands on the shoulders of generations of taxon experts who came before.  Our obligation is to use the received body of accumulated knowledge, theories and methods to advance our understanding of species diversity and its origins.  To leave descriptions, species inventories and classifications in better shape than we found them.  Unless taxonomists stand up for the integrity and excellence of their own science—the greatest symbol of which are comprehensively comparative and descriptive revisions and monographs—then they share blame for the demise of systematics as much as general biologists, ignorant of the intricacies of taxonomic thought and best practices, who selfishly care only that the information they need to tell species apart is provided and are quite happy to see the science of systematics reduced to a parody of itself.

Like the television program To Tell the Truth, we are now confronted with both the real taxonomy and imposters.  At present, the applied, molecular imposter is stealing the show.  But science and society are ultimately best served only when fundamental taxonomy is recognized and supported.  It is time for the real taxonomy to stand up, to reassert its mission, ideas and scholarship, to insist that it be done to its highest levels of excellence, and to put molecular data in its place as one of several sources of evidence, no better, and for critically important purposes less important, than others, including comparative morphology and paleontology.

Only when taxonomists stand up for their own science will the tail stop wagging the dog.  Users of taxonomic information just want answers; they are not concerned with the details of comparative, descriptive studies, or the scientific integrity of taxonomy, nor should they be.  They have their own scientific goals to protect and advance.  But for taxonomists to willingly sell out the integrity of their own science for short term popularity or profits is inexcusable.  Taxonomy must reassert itself now, defined on its own terms, driven by its own questions and goals, and uncompromised in a mission unique among all other biological disciplines.  Too much time has been wasted in recent years bending to the priorities of others, cowering or conforming rather than defending the aims of systematics.  Unless we draw a line in the sand now, we will condemn science and all generations who follow to an unnecessarily deep pit of ignorance where knowledge and enlightenment could exist.  For a myriad of reasons, from informing environmental and conservation science with the most, and most reliable, information to revealing the amazing history of descent with diversification, it is imperative that the real taxonomy stand up for itself now.

The real taxonomy is devoted to the exploration and study of species themselves as well as their attributes and relationships.  It inventories the kinds that exist, informing us of the ways in which they are unique or similar to one another.  It provides a vocabulary of biodiversity through biological nomenclature.  And it organizes all that we know in an informative, predictive, phylogenetically-informed classification.  In spite of its importance to biology as a whole, being able to identify species is a by-product of taxonomic knowledge, not its raison d’etre.

I find recent images from the James Webb telescope incredibly exciting, opening a window on the universe for our increased understanding of its diverse components, organization and history.  It may not cure cancer or conserve tigers, but the Webb telescope lifts the human spirit and creates new opportunities to explore and learn.  The same may be said of the biosphere and evolutionary history, a living universe much closer to home that we have the innate yearning to also explore and understand—just because they exist.  Only by supporting real taxonomy, on its own terms, can we be led to unexpected discoveries, insights, marvels and understanding.  Taxonomy should remain a reliable partner to the life sciences making species identifiable, but as a fringe benefit of a fundamental science exploring all relevant evidence, not limited to expediencies for identification.  A fundamental science that explores the kinds of life that exist due to evolutionary history simply because they exist and can tell us about the origins of ourselves and our world.  Following our curiosity to discover and understand what species exist and what makes each unique enriches our intellectual lives, deepens our scientific comprehension of the world, and prepares us to deal with issues of biodiversity from agriculture to conservation and biomimicry.  None of these benefits are fully accrued by species reduced to mere DNA barcodes or identified in a way divorced from deep knowledge of species themselves.  Science and humankind need the real taxonomy just as they need the real physics, astronomy and chemistry to expand our knowledge, create new opportunities, and open new horizons of understanding.

Of course, we must address the immediate need to identify species in response to a rapidly changing biosphere and urgent need to develop meaningful conservation goals and better understand the components of ecosystems.  Of course, we ought to stockpile knowledge of the attributes of species as the raw material for biomimetic solutions to challenges we face.  But in addition to the practical impacts of taxonomic knowledge, we owe it to ourselves to support taxonomists to explore species and phylogeny because it enriches our lives, ennobles us as scient, curious beings, and continues a tradition of exploring the unknown that is as old as science itself.  Extinction rates means that the time to fully explore species and phylogeny is limited, so, before it is too late, will the real taxonomy please stand up?

Reference

Wilson, J.J. 2011. Taxonomy and DNA sequence databases: a perfect match? Terrestrial Arthropod Reviews 4: 221–236. DOI 10.1163/187498311X591111 [This article is one of many examples of the trend toward a molecular-based taxonomy, ignoring most of what makes species exploration most interesting and valuable, including morphological characters and formal phylogenetically-structured classifications. Already firmly rooted more than a decade ago, this trend continues to transform taxonomy into a mere identification/phylogeny service. It is telling that the need to test morphological homology hypotheses is regarded by Wilson as a negative, rather than as a strength as in every other science!]