Chapter 2 Biological Nomenclature Biologic categorization is one of the most conspicuous aspects of successful behavior, not only of man, but of all animals, in meeting the requirements for survival in a complex environment. – Dunn and Davidson (1968:75) Linnaean nomenclature came to be universally employed by scientists, though initially it met with little enthusiasm by non-scientists. Even today many people are repelled by scientific names. – Evans (1993:12) Humans as Taxonomists We are all taxonomists. Pattern seeking and the urge to classify our environment are part of our biology. Like other animals, we need such behavior to tell food from nonfood, predator from nonpredator, and to recognize potential mates, relatives, and offspring. As human animals, we put our conclusions into words and names (Dunn and Davidson 1968; Raven et al. 1971; Pinker 1995). We also use classification in our daily lives to create order and to make things easier to find. We devise our own schemes for household organization–socks in one bureau drawer, shirts in another–to make dressing faster so we can grab an extra 5 minutes of sleep. And we depend on classifications made up by others to make books easier to find in the library, canned peaches in the supermarket, or a new pair of jeans in a department store. We can observe taxonomic behavior in children’s development: the excitement of a toddler as she learns to name the components of her world, or the concentration of a preschooler as he manipulates the pieces of a simple wooden puzzle. 20 INTRODUCTION Yet some children like puzzles better than others, and some adults are more interested than others in searching for patterns in their world. This may be at least partially due to innate differences in brain function and learning style. Most students of the mind now believe that intelligence is a not a single property, but rather a number of distinct capacities: linguistic, logical–mathematical, spatial, musical, bodily-kinesthetic, and so on. Children doing puzzles are using and developing their logical– mathematical, spatial, and kinesthetic abilities (Gardner 1983). If they also become interested in biology, young puzzle-lovers might well grow up to become professional taxonomists. Spatial intelligence, in particular, is important to taxonomists, whose science involves the mental sorting and manipulation of characters and taxa, cladograms, and trees. Unlike exceptional mathematical ability, which usually develops very early, but in which peak ability and contributions to the field come in adolescence and early adulthood, unusual spatial ability can manifest itself early and persist until late in life (Gardner 1983). The importance of spatial intelligence in taxonomy might explain why its mastery has often been likened to the mastery of visual arts such as painting, in which talent is often shown very early and technical mastery and creative expression continue to develop throughout life. Some unconscious perception that an innate combination of abilities is involved may explain the conflicting feelings I have heard expressed by taxonomists and other scientists that taxonomists are born, not made, but that it takes 50 years to become a master of the field. It may also explain why scientists in some other fields have had difficulty accepting systematics as science rather than art. However, despite our common human heritage as taxonomists, most of us, whether students, scientists, or even practicing systematists, have little patience with the nomenclatural aspect of the field. If we must deal with the codes of nomenclature, we can find ourselves reacting with irritation to their inconsistencies and contradictions, and behaving as if these rules had appeared engraved in stone for no other reason than to plague us. There is some justification for this reaction. The codes that govern the biological naming of plants and animals are written in a legal style and language. The aim of their authors was to make their terminology so precise that the meaning of each regulation could not be misconstrued. Unfortunately, it seems to have had the opposite effect, producing a legalese often completely impenetrable to the uninitiated. Even when their language has been decoded, reading a code of nomenclature is Biological Nomenclature 21 about as stimulating for most of us as reading a will in which we are not beneficiaries. However, because the chief purpose of this book is to enable you to research, write, and publish taxonomic descriptions–all activities that involve nomenclature–it must cover the subject in some detail. The rest of this chapter surveys the development of biological nomenclature, showing that much about the way we name things is consistent across cultures and over time. It also summarizes the history of our present codes of botanical and zoological nomenclature, pointing out what basic concepts they share and in what ways they differ. Finally, it discusses the inherent limitations and future of the current system. Biological Nomenclature Biologists have divided the living world into groups of organisms, or taxa, which they have arranged in a series of levels, or a taxonomic hierarchy (table 2.1), with the species (chapter 3) as its essential element. Below species are subspecies, populations, and individuals. Above the species level, taxa are grouped into more and more inclusive levels, based on fewer shared features. The levels of this taxonomic hierarchy are given names, or taxonomic ranks. Species sharing similar features are grouped into a genus, genera sharing traits into a family, families into orders, orders into classes, classes into Phyla (animals) or Divisions (plants), up to the broadest level of Kingdom (table 2.1). All taxa at the same level or rank belong to the same taxonomic category. Assigning names to these groupings is the part of taxonomy called nomenclature. By agreement among biologists, scientific names are assigned or reassigned according to sets of rules called codes of nomenclature. Biologists first began arranging taxa into hierarchies on the basis of shared features long before there was any understanding of the genetics and evolutionary basis of such similarities. Now, although the present system is not perfect or complete (and never can be because it is a compromise system), most biologists share the goal of attempting to make ensure that the groupings used reflect a common evolutionary history. This is deduced by making use of structures similar in a certain way (by homology), particularly by the use of the shared, derived features that give the best information, as well as by aspects of body chemistry, physiological processes, and genetics at both the organismic and molecular level. Table 2.1 Folk and Scientific Taxonomic Hierarchies Folk Classification Biological Classification Group Group Name Group Group Name Example 1 Example 2 Example 1 Example 2 Life form yakt* as† Kingdom Animalia Animalia Phylum Chordata Chordata Class Amphibia Aves Order Anura Falconiformes Family Hylidae Accipitridae Generic ccp as Genus Hyla Accipiter Specific ccp kamayket as jejeg Species Hyla angiana Accipiter melanochlamys Varietal as jejeg km Subspecies Unnamed variant‡ Sources: Karam names from Bulmer and Tyler 1968; Bulmer 1970. Scientific names from Bulmer and Tyler 1968; Bulmer 1970; Barnes 1984; Peterson 1980. * Flying birds or bats. † “Soft food,” frogs and certain small mammals. ‡ Avariant of this highly variable species with upper surface mostly green. Biological Nomenclature 23 As mentioned in chapter 1, there are actually five nomenclatural codes, but this book covers only those for plants and animals. Animals are named and described according to the International Code of Zoological Nomenclature (ICZN), of which the latest edition is the third edition, published in 1985. The fourth edition is now in press, with publication expected in mid-1999, to come into effect on 1 January 2000. The ICZN is currently regulated by the International Union of Biological Sciences (IUBS). Plants are named and described following the International Code of Botanical Nomenclature (ICBN), currently under the jurisdiction of the International Botanical Congress. The latest edition is the Tokyo Code, published in 1994. It will be revised again at the next International Botanical Congress, scheduled to be held at the Missouri Botanical Garden, St. Louis, in July 1999. Farfrom being written in stone, the present rules are the result of many hard-fought scientific battles over the last 200 years. They represent the best compromise taxonomists have come up with to deal with two diametrically opposing needs: the need to name, to provide each organism with a unique and stable name; and the need to classify, to provide a system of classification that is explanatory and predictive. They are opposing because if the criterion of stability is to be met, a name once given could never be changed. Yet, as chapter 1 showed, we still have a lot to learn about relationships and even identities of Earth’s organisms, so the ability to continue to make changes that reflect increasing knowledge is vital. Each code is made up of a set of rules or articles that must be followed when taxa are named or names used or changed. Some of the rules are accompanied by recommendations, which point out what is currently considered to be the best procedure to follow in specific instances. There is no enforcement of these rules except the voluntary cooperation of biologists. But these voluntary sanctions are quite effective. No work that goes against them is likely to be published in a reputable journal, and if such work should get published, it will probably be ignored (Jeffrey 1989). Folk Taxonomy The system we use for the scientific naming of organisms developed over avery long period of time. Its roots go back to prehistory, maybe even to prehuman history. Some historians believe that the scientific study of living things developed via primitive medicine (Hopwood 1959). In that 24 INTRODUCTION case, taxonomy may well date back to prehuman primates, for scientists have recently realized that a number of primates dose themselves with medicinal plants to combat various complaints (Gibbons 1992; Clayton and Wolfe 1993).