Tuesday, March 22, 2016

The Importance of Biological Taxonomy

Biological taxonomy is the scientific field dealing with the classification of living organisms. Non-biologists who give any thought to taxonomy, may think that the field is the dullest of the sciences. To the uninitiated, there is little difference between the life of a taxonomist and the life of a stamp collector. Nothing could be further from the truth. Taxonomy has become the grand unifying theory of the biological sciences. Efforts to sequence the genomes of prokaryotic, eukaryotic and viral species, thereby comparing the genomes of different classes of organisms, have revitalized the field of evolutionary taxonomy (phylogenetics). The analysis of normal and abnormal homologous genes in related classes of organisms have inspired new disease treatments targeted against specific molecules and pathways characteristic of species or classes or organisms. Students who do not understand the principles of modern taxonomy have little chance of perceiving the connections between medicine, genetics, pharmacology, or pathology, to say nothing of clinical microbiology.

Here are two of the specific advantages of learning the taxonomy of infectious diseases.
1. As a method to drive down the complexity of medical microbiology

Learning all the infectious diseases of humans is an impossible task. As the number of chronically ill and immune-compromised patients has increased, so have the number of opportunistic pathogens. As global transportation has become commonplace, the number of exotic infections spread worldwide has also increased (See Glossary item, Exotic diseases in the United States). A few decades ago, infectious disease experts were expected to learn a few hundred infectious diseases. Today, there are over 1400 organisms that can cause diseases in humans, and the number is climbing rapidly, while the techniques to diagnose and treat these organisms are constantly improving. Textbooks cannot cover all these organisms in sufficient detail to provide healthcare workers with the expertise to provide adequate care to their patients.

How can any clinician learn all that is needed to provide competent care to patients? The first step in understanding infectious diseases is to understand the classification of pathogenic organisms. Every known disease-causing organisms has been assigned to one of 40 well-defined classes of organisms, and each class fits within a simple ancestral lineage. This means that every known pathogenic organism inherits certain properties from its ancestral classes and shares these properties with the other members of its own class. When you learn the class properties, along with some basic information about the infectious members of the classes, you gain a comprehensive understanding of medical microbiology.

2. As protection against professional obsolescence

There seems to be so much occurring the the biological sciences, it is just impossible to keep on top of things. With each passing day, you feel less in tune with modern science, and you wish you could return to a time when a few fundamental principles grounded your chosen discipline. You will be happy to learn that science is all about finding generalizations among data or among connected systems (i.e., reducing the complexity of data or finding simple explanations for systems of irreducible complexity). Much, if not all, of the perceived complexity of the biological sciences derives from the growing connections of once-separate disciplines: cell biology, ecology, evolution, climatology, molecular biology, pharmacology, genetics, computer sciences, paleontology, pathology, statistics, and so on. Scientists today must understand many different fields, and they must be willing and able to absorb additional disciplines, throughout their careers. As each field of science becomes entangled with other the seemingly arcane field of biological taxonomy has gained prominence because it occupies the intellectual core of virtually every biological field.

Modern biology is data-driven. A deluge of organism-based genomic, proteomic, metabolomic and other "omic" data is flooding our data banks and drowning our scientists. This data will have limited scientific value if we cannot find a way to generalize the data collected for each organism to the data collected in other organisms. Taxonomy is the scientific method that reveals how different organisms are related. Without taxonomy, data has no biological meaning.

The discoveries that scientists make in the future will come from questions that arise during the construction and refinement of biological taxonomy. In the case of infectious diseases, when we find a trait that informs us that what we thought was a single species is actually two species, it permits us to develop treatments optimized for each species, and to develop new methods to monitor and control the spread of both organisms. When we correctly group organisms within a common class, we can test and develop new drugs that are effective against all of the organisms within the class, particularly if those organisms are characterized by a molecule, pathway or trait that is specifically targeted by a drug. Terms used in diverse sciences, such as homology, metabolic pathway, target molecule, acquired resistance, developmental stage, cladistics, monophyly, model organism, class property, phylogeny, all derive their meaning and their utility from biological taxonomy. When you grasp the general organization of living organisms, you will understand how different scientific fields relate to each other, thus avoiding professional obsolescence.

- Jules Berman (copyrighted material)

key words: taxonomy, evolution, classification, data organization, jules j berman

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